EXTRUSION COMPOSITIONS COMPRISING RECYCLED POLYAMIDES FROM THE EXPLOITATION OF OIL OR GAS DEPOSITS, UNDER THE SEA OR ON LAND.

Abstract

The present invention relates to an extrusion composition comprising by weight: a) from 35 to 100%, in particular from 35 to 96.9%, of at least one semi-crystalline aliphatic polyamide PA1 comprising at least 30%, in particular at least 50%, of recycled semi-crystalline aliphatic polyamide PA2 from used or end-of-life pipelines from subsea or onshore oil or gas fields, in particular subsea, said recycled semi-crystalline aliphatic polyamide PA2 having undergone a washing and / or compounding step after removal and grinding into granules of said pipeline; b) from 0 to 65%, in particular from 0 to 10%, of at least one reinforcing fiber; c) from 0 to 40%, in particular from 3 to 30%, of at least one impact modifier;d) from 0 to 30%, in particular 0 to 15% of a filler, e) from 0 to 10%, in particular from 0.1 to 5% of at least one additive, the sum of components a + b + c + d + e is equal to 100%, the inherent viscosity of said composition, as determined according to ISO 307:2007 in m-cresol at 20°C being greater than or equal to 1.2 dl / g, in particular from 1.2 dl / g to 1.7 dl / g.;

Description

Title of the invention: EXTRUSION COMPOSITIONS COMPRISING RECYCLED POLYAMIDES DERIVED EXPLOITATION OF OIL OR GAS DEPOSITS, UNDER THE SEA OR ON LAND.

[0001] The present invention relates to compositions for extrusion comprising recycled polyamides from the exploitation of oil or gas deposits, under the sea or on land. Previous technique

[0002] In the exploitation of oil or gas fields, whether offshore or onshore, flexible pipes are necessary to connect the various devices around the platform. These pipes must withstand hot oil, gas, water, and mixtures of at least two of these products for periods of up to 20 years. These pipes generally consist of a non-watertight inner metallic layer formed by a profiled metal strip wound in a helical fashion, such as a stapled metal strip, which gives the pipe its shape. A polymer is then extruded onto this layer to provide a watertight seal, and finally, other protective and reinforcing layers, such as metal fiber mats and rubber, are added.

[0003] Long chain polyamides have been used for years for the exploitation of oil or gas deposits, under the sea or on land.

[0004] However, it is necessary to clean these hoses by circulating methanol through them, for example, to remove the hydrates. The disadvantage of methanol is that it penetrates the polyamide strongly. Therefore, there are losses of methanol, and it can also extract the plasticizer and / or modifiers from the polyamide, leading to a degradation of the mechanical properties and premature aging of the hose.

[0005] Furthermore, several tens to hundreds of tons of long-chain polyamides from oil or gas field production pipes, whether offshore or onshore, will need to be recycled in the coming years because they have reached the end of their service life. However, these polyamides cannot be used after simple shredding due to the pollutants from the extracted oil or gas that they contain.

[0006] Polyamides (PA) from oil or gas field production pipes, underwater or on land, cannot be used as is.

[0007] They must be ground in order to be transformed into a part having a different shape for a different application.

[0008] After shredding, the polyamide to be recycled must also be washed and / or compounded in order to extract a large majority of pollutants (with solvents, in melt, under vacuum...). However, the extraction is not necessarily complete.

[0009] Without this washing and / or compounding step, the manufactured parts exude. This exudate can be toxic to the user and can generate a greasy appearance on the parts.

[0010] Furthermore, the polyamides to be recycled may be largely hydrolyzed and therefore cannot be extruded. In this case, they must be exposed to a high vacuum (possibly with the addition of a catalyst) to increase their viscosity and make them extrudable.

[0011] It is therefore necessary to have a composition which allows, on the one hand, to be extruded safely for the operator (no release of toxic gas) and, on the other hand, to obtain all types of extruded parts which are stable over time (no exudation).

[0012] The present invention therefore relates to an extrusion composition comprising by weight:

[0013] a) from 35 to 100%, in particular from 35 to 96.9 of at least one semi-crystalline aliphatic polyamide PA1 comprising at least 30%, in particular at least 50% of recycled semi-crystalline aliphatic polyamide PA2 from used or end-of-life pipelines from offshore or onshore oil or gas fields, in particular offshore, said recycled semi-crystalline aliphatic polyamide PA2 having undergone a washing and / or compounding step after removal and grinding into granules of said pipeline;

[0014] b) from 0 to 65%, in particular 0 to 10% of at least one reinforcing fiber;

[0015] c) from 0 to 40%, in particular from 3 to 30% of at least one shock modifier;

[0016] d) from 0 to 30%, in particular 0 to 15% of a charge,

[0017] e) from 0 to 15%, in particular from 0.1 to 10%, notably from 0.5 to 5% of at least one additive,

[0018] the sum of the components a + b + c + d + e is equal to 100%,

[0019] the inherent viscosity of said composition, as determined according to ISO 307:2007 in m-cresol at 20°C being greater than or equal to 1.2 dl / g, in particular between 1.2 dl / g and 1.7 dl / g.

[0020] The inventors have therefore found that adding recycled polyamide PA2, derived from used or end-of-life pipelines from offshore or onshore oil and gas fields, particularly offshore, to virgin polyamide PA1 yields an extrudable composition without the release of harmful or toxic gases (ensuring operator safety), for producing all types of extruded parts that do not exude or exhibit minimal exudation. The compositions of the invention exhibit good mechanical properties, enabling improved weld quality and productivity between two parts.

[0021] The exploitation of oil or gas deposits under the sea or onshore gas uses flexible pipes to connect the various underwater or onshore devices respectively of the platform and conveying the extracted hydrocarbons.

[0022] These pipes must withstand hot oil, gas, water and mixtures of at least two of these products for periods of up to 20 years.

[0023] The term "used" means that the pipe has already been used for the exploitation of oil or gas fields, whether subsea or onshore, but has not yet reached its service life limit of up to 20 years. The cessation of production on a platform and its dismantling explains the need to recycle this type of pipe, which is not yet at the end of its life.

[0024] The term "end of life" means that the pipe has been used for the exploitation of oil or gas fields, whether subsea or onshore, but has reached its service life limit of up to 20 years. These pipes must therefore be removed from the operating system before they become completely degraded or develop a leakage problem with respect to the transported oil or gas.

[0025] Regarding semi-crystalline aliphatic polyamide PA1

[0026] The PA1 polyamide can be a homopolyamide or a copolyamide or a mixture of these.

[0027] Semi-crystalline aliphatic polyamide is understood to be a material which is generally solid at room temperature, and which softens when the temperature increases, in particular after passing its glass transition temperature (Tg), and which may exhibit a clear melting when passing its so-called melting temperature (Tf), and which becomes solid again when the temperature decreases below its crystallization temperature.

[0028] Tg, Te and Tf are determined by differential scanning calorimetry (DSC) according to standard 11357-2:2013 and 11357-3:2013 respectively.

[0029] The average number molecular mass Mn of said semi-crystalline polyamide is preferably in a range from 10000 to 85000, in particular from 10000 to 60000, preferably from 10000 to 50000, even more preferably from 12000 to 50000.

[0030] The nomenclature used to define polyamides is described in ISO 1874-1:2011 "Plastics - Polyamide (PA) materials for molding and extrusion - Part 1: Designation", in particular on page 3 (tables 1 and 2) and is well known to those skilled in the art.

[0031] Said at least one aliphatic semi-crystalline polyamide PA1 can be obtained from the polycondensation of at least one lactam, or from the polycondensation of at least one amino acid, or from the polycondensation of at least one diamine X with at least one dicarboxylic acid Y or mixtures thereof.

[0032] When said at least one aliphatic semi-crystalline polyamide PA1 is obtained from the polycondensation of at least one lactam, said at least one lactam may be selected from a lactam in the range of C6 to Cl8, C8 to Cl8, preferably in the range of C10 to C18, more preferably in the range of C10 to C12. A lactam in the range of C6 to Cl8 is in particular ca-prolactam, decanolactam, undecanolactam, and lauryllactam.

[0033] When said at least one aliphatic semi-crystalline polyamide PA1 is obtained from the polycondensation of at least one lactam, it may therefore comprise a single lactam or several lactams.

[0034] Advantageously, said at least one aliphatic semi-crystalline polyamide PA1 is obtained from the polycondensation of a single lactam and said lactam is chosen from lauryllactam and undecanolactam, advantageously lauryllactam.

[0035] When said at least one aliphatic semi-crystalline polyamide PA1 is obtained from the polycondensation of at least one amino acid, said at least one amino acid may be chosen from an amino acid in C8 to Cl8, preferably in C10 to C18, more preferably in C10 to C12.

[0036] A C8 to C18 amino acid is in particular 9-aminononanoic acid, 10-aminodecanoic acid, 10-aminoundecanoic acid, 12-aminododecanoic acid and 11-aminoundecanoic acid and its derivatives, in particular N-heptyl-11-aminoundecanoic acid.

[0037] When said at least one aliphatic semi-crystalline polyamide PA1 is obtained from the polycondensation of at least one amino acid, it may therefore comprise a single amino acid or several amino acids.

[0038] Advantageously, said aliphatic semi-crystalline polyamide PA1 is obtained from the polycondensation of a single amino acid and said amino acid is selected from 10-aminodecanoic acid, 11-aminoundecanoic acid and 12-aminododecanoic acid, advantageously 11-aminoundecanoic acid.

[0039] When said at least one aliphatic semi-crystalline polyamide PA1 is obtained from the polycondensation of at least one diamine X with at least one aliphatic dicarboxylic acid Y, the diamine X is in C4-C36, preferably C6-C18, preferably C6-C12, more preferably C10-C12 and said aliphatic dicarboxylic acid Y is in C6-C36, preferably C6-C18, preferably C6-C12, more preferably C10-C12

[0040] The diamine can be linear or branched. Advantageously, it is linear.

[0041] Said at least one diamine X in the C4-C36 group may in particular be selected from 1,4-butanediamine, 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethyldiamine, 1,13-tridecamethylenediamine, 1,14-tetradecamethylenediamine, 1,16-hexadecamethylenediamine and 1,18-octadecamethylenediamine, octadecenediamine, reicosanediamine, docosanediamine and diamines obtained from fatty acids.

[0042] Advantageously, said at least one diamine X is in C4-C18 and selected from 1,4-butanediamine, 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine, 1,13-tridecamethylenediamine, 1,14-tetradecamethylenediamine, 1,16-hexadecamethylenediamine and 1,18-octadecamethylenediamine.

[0043] Advantageously, said at least one diamine X in C6 to C12, is in particular selected from 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine.

[0044] Advantageously, said at least one diamine X in C6 to C12, is in particular selected from 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine.

[0045] Advantageously, the diamine X used is in C12 C10, in particular chosen from 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine.

[0046] Said at least one dicarboxylic acid Y in C6 to C36 may be selected from 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.

[0047] The diacid can be linear or branched. Advantageously, it is linear.

[0048] Advantageously, said at least one dicarboxylic acid Y is in C6 to Cl8 and is selected from adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, octadecanedioic acid.

[0049] Advantageously, said at least one dicarboxylic acid Y is in C6 to C12 and is selected from adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid.

[0050] Advantageously, said at least one dicarboxylic acid Y is in C12 C10 and is selected from sebacic acid, undecanedioic acid, dodecanedioic acid.

[0051] When said aliphatic semi-crystalline polyamide PA1 is obtained from the polycondensation of at least one diamine X with at least one dicarboxylic acid Y it can therefore comprise a single diamine or several diamines and a single dicarboxylic acid or several dicarboxylic acids.

[0052] Advantageously, said aliphatic semi-crystalline polyamide PA1 is obtained from the polycondensation of a single diamine X with a single dicarboxylic acid Y.

[0053] In one embodiment, the recycled semi-crystalline aliphatic polyamide PA1 is a long-chain polyamide having an average number of carbon atoms per nitrogen atom greater than 7, in particular greater than 9.

[0054] Regarding recycled semi-crystalline aliphatic polyamide PA2

[0055] The PA2 polyamide can be a homopolyamide or a copolyamide or a mixture of these.

[0056] Semi-crystalline aliphatic polyamide is understood to be a material which is generally solid at room temperature, and which softens when the temperature increases, in particular after passing its glass transition temperature (Tg), and which may exhibit a clear melting when passing its so-called melting temperature (Tf), and which becomes solid again when the temperature decreases below its crystallization temperature.

[0057] Tg, Te and Tf are determined by differential scanning calorimetry (DSC) according to standard 11357-2:2013 and 11357-3:2013 respectively.

[0058] The average number molecular mass Mn of said semi-crystalline polyamide is preferably in a range from 10000 to 85000, in particular from 10000 to 60000, preferably from 10000 to 50000, even more preferably from 12000 to 50000.

[0059] Said at least one semi-crystalline aliphatic polyamide PA2 was initially obtained prior to use for the exploitation of oil or gas fields from the polycondensation of at least one lactam, or from the polycondensation of at least one amino acid, or from the polycondensation of at least one diamine X with at least one dicarboxylic acid Y or mixtures thereof as described above for semi-crystalline aliphatic polyamide PAL

[0060] Advantageously the PA 2 is a PA 11 or PA 12, in particular the PAU.

[0061] After use, i.e. when it is worn out or at the end of its life, the oil or gas production pipeline, whether offshore or onshore, particularly offshore, is removed from the production platform, the different layers are separated, and the layers containing PA 2 are ground into a granulate (0.5 mm to 25 mm) or powder (to a size less than 0.5 mm) and then washed and / or Compounded, meaning that the ground material, after washing or not, is fed at least once into an extruder, particularly a twin-screw co-rotating type, or a comalaxer type (Buss), where the ground material is remixed by melting, with or without the addition of at least one catalyst. The molten material exits the extruder in rods which are cooled and cut into granules.

[0062] Advantageously, the number of compoundings is from 1 to 10, in particular from 1 to 5, in particular the number of compoundings is 1, 2, 3, 4 or 5, in particular 1, 2 or 3.

[0063] Washing the crushed material, when it takes place, can be carried out in particular by means of a solvent, in particular methanol, ethanol, in order to extract a large majority of pollutants, as described later and originating from the operation.

[0064] Compounding, when it takes place, can be carried out with the addition of a catalyst.

[0065] The term “catalyst” refers to a polycondensation catalyst such as a mineral or organic acid.

[0066] Advantageously, the proportion by weight of catalyst is from about 50 ppm to about 5000 ppm, in particular from about 100 to about 3000 ppm relative to the total weight of the composition.

[0067] Advantageously, the catalyst is chosen from phosphoric acid (H3PO4), phosphorous acid (H3PO3), hypophosphorous acid (H3PO2), or a mixture of these.

[0068] Advantageously, the present invention therefore relates to the above-defined use of at least one catalyst, in proportion by weight of catalyst of about 50 ppm to about 5000 ppm, in particular about 100 to about 3000 ppm relative to the total weight of the composition, of at least one copper thermal stabilizer and of at least one oligo- or poly-carbodiimide, with a matrix comprising at least one thermoplastic polymer, in particular a polyamide, said catalyst being selected from phosphoric acid (H3PO4), phosphorous acid (H3PO3), hypophosphorous acid (H3PO2), or a mixture thereof.

[0069] Advantageously, the catalyst is chosen from phosphoric acid (H3PO4), phosphorous acid (H3PO3) in a proportion of about 100 to about 3000 ppm.

[0070] In one embodiment, the PA2 mixture to be recycled is degassed during compounding.

[0071] In one embodiment, the outgassing is low, meaning that the outgassing is between -50 mmHg and -150 mmHg.

[0072] For example, it is carried out according to the following protocol A:

[0073] The crushed tube, washed or not, is compounded on a Coperion / Wemer twin-screw extruder 40mm, 70kgh, 300rpm, 270°C setpoint, with a degassing of -100mmHg.

[0074] In another embodiment, the outgassing is strong, meaning that the outgassing is from -550 mmHg to -750 mmHg.

[0075] For example, it is carried out according to the following protocol B:

[0076] The crushed tube, washed or not, is compounded on a Coperion / Wemer twin-screw extruder 40mm, 70kg / h, 300rpm, 270°C setpoint, with a strong degassing of -660mmHg.

[0077] Advantageously the degassing is located just after the melting zone in the extruder.

[0078] The inherent viscosity of the semi-crystalline aliphatic polyamide after grinding and washing or after grinding and compounding with or without a catalyst, or after grinding, washing and compounding with or without a catalyst, as determined according to ISO 307:2007 in m-cresol at 20°C is greater than or equal to 1.2 dl / g, in particular between 1.2 dl / g and 1.7 dl / g.

[0079] The ground, washed and / or compounded semi-crystalline aliphatic polyamide, with or without catalyst, with or without degassing, therefore corresponds to the recycled semi-crystalline aliphatic polyamide PA2 of the composition of the invention.

[0080] In one embodiment, the recycled semi-crystalline aliphatic polyamide PA2 is a long-chain polyamide having an average number of carbon atoms per nitrogen atom greater than 7, in particular greater than 9.

[0081] In particular, recycled semi-crystalline aliphatic polyamide PA2 is a long-chain polyamide having an average number of carbon atoms per nitrogen atom of more than 7 to 12, in particular more than 7 to 11, in particular more than 9 to 12, in particular more than 9 to 11.

[0082] In another embodiment, said recycled semi-crystalline aliphatic polyamide PA2 comprises at least one species selected from alkanes, C14-C18 aliphatic mono-acids, mono- or poly-aromatic compounds and aromatic acids.

[0083] The alkanes include methylcyclopentane, cyclohexane, methylcyclohexane, 1,2-cis-dimethylcyclohexane, 1,2-trans-dimethylcyclohexane, 1,3-cis-dimethylcyclohexane, 1,3-trans-dimethylcyclohexane, 1,4-cis-dimethylcyclohexane, 1,4-trans-dimethylcyclohexane, or ethylcyclohexane.

[0084] C14 to C18 aliphatic monoacids include palmitic acid and stearic acid.

[0085] Said C14 to C18 aliphatic mono acids are also present in the initial virgin semi-crystalline aliphatic polyamide (from 1 to 100 ppm) but are present in higher concentrations in the recycled semi-crystalline aliphatic polyamide PA2 (plus 100 ppm), in particular from 500 to 5000 ppm.

[0086] Mono- or poly-aromatic compounds include, in particular, toluene, xylene, trimethylbenzene, methyl diphenyl and diphenyl methanol, naphthalene, 1-methylnaphthalene, 2-methylnaphthalene, 1,2-dimethylnaphthalene, 1,3-dimethylnaphthalene, 1,4-dimethylnaphthalene, 1,3,6-trimethylnaphthalene, 2,3,5-trimethylnaphthalene, 1-phenanthrene, 2-methylphenanthrene.

[0087] Aromatic acids include benzoic acid, 2-methylbenzoic acid, 3-methylbenzoic acid, 4-methylbenzoic acid, 2,5-dimethylbenzoic acid, 3,4-dimethylbenzoic acid, 2,4-dimethylbenzoic acid and 3,5-dimethylbenzoic acid.

[0088] Advantageously, said recycled semi-crystalline aliphatic polyamide PA2 comprises at least one species selected from sulfur compounds, alkanes, C14-C18 aliphatic mono-acids, mono- or poly-aromatic compounds and aromatic acids.

[0089] More advantageously, said recycled semi-crystalline aliphatic polyamide PA2 comprises at least one species selected from alkanes, mono- or poly-aromatic compounds and aromatic acids.

[0090] Even more advantageously, said recycled semi-crystalline aliphatic polyamide PA2 comprises at least one species selected from alkanes and mono- or poly-aromatic compounds.

[0091] Advantageously, said recycled semi-crystalline aliphatic polyamide PA2 comprises at least one species selected from alkanes such as methylcyclopentane, cyclohexane, methylcyclohexane, 1,2-cis-dimethylcyclohexane, 1,2-trans-dimethylcyclohexane, 1,3-cis-dimethylcyclohexane, 1,3-trans-dimethylcyclohexane, 1,4-cis-dimethylcyclohexane, 1,4-trans-dimethylcyclohexane, or ethylcyclohexane and mono- or poly-aromatic compounds such as toluene, xylene, trimethylbenzene, methyl diphenyl and methanol diphenyl, naphthalene, 1-methylnaphthalene, 2-methylnaphthalene, 1,2-dimethylnaphthalene, the 1,3-dimethylnaphthalene, 1,4-dimethylnaphthalene, 1,3,6-trimethylnaphthalene, 2,3,5-trimethylnaphthalene, 1-phenanthrene, 2-methylphenanthrene.

[0092] In one embodiment, the molar content of said species present in the recycled semi-crystalline aliphatic polyamide PA2 is from 100 ppm to 2000 ppm, in particular from 100 ppm to 1000 ppm.

[0093] In another embodiment, the recycled semi-crystalline aliphatic polyamide PA2 has a characteristic odor comprising sulfur / pyrogenized and / or hydrocarbon and / or aromatic, terpenic and phenolic poles.

[0094] The above odors are determined according to the description of the field of odors® by Jean-Noël Jaubert.

[0095] The field of odors, developed in 1983, provides, among other things, a methodology which This method allows for a standardized description of olfactory perceptions, minimizing individual impressions. It was created by researcher Jean-Noël Jaubert based on the results of a research program investigating the relationship between chemical structure and odorant activity in molecules found in the olfactory world. Initially developed for the perfume industry, this method has enabled the description, analysis, comparison, and control of complete products or odorous preparations, going beyond conventional classifications.

[0096] Discomfort related to odor problems is a signature of recycled polyamide.

[0097] This discomfort is perceived when opening the containers of washed or unwashed ground material, or during extrusion and possibly on the finished product.

[0098] Recycled polyamides have sulfurous or aromatic odorant poles (odor of aromatic solvent, naphthalene). A distinct difference can be perceived between a virgin polyamide and a recycled polyamide.

[0099] In yet another embodiment, the recycled semi-crystalline aliphatic polyamide PA2 has functions resulting from thermolysis reactions in acidic medium, in particular amide functions and / or methylene in alpha of said amide functions and acidic chain ends, chosen from nitrile, ketone, and ester functions resulting from reaction of the acid functions of the polyamide with alcohols used during the life of said pipes, in a molar ratio with respect to the amide functions greater than that of the same polyamide constituting an unused pipe.

[0100] In one embodiment, the molar ratio of functions resulting from thermolysis reactions is from 1 / 10000 to 1 / 20 as determined by proton NMR.

[0101] Concentrations can be measured by proton NMR in dichlo-romethane-d2, by adding HFIP (hexafluoroisopropanol) to solubilize the polyamide.

[0102] During oil extraction, alcohols such as ethanol are used which can react with the acid functions of the semi-crystalline aliphatic polyamide initially present to lead to ester functions.

[0103] In one embodiment, said recycled semi-crystalline aliphatic polyamide PA2 comprises a proportion of cyclic oligomers, selected from oligomers having a molar mass of less than 1000 g / mol, lower than that of the equivalent virgin polyamide.

[0104] The cyclic oligomer content is measured according to the following protocol:

[0105] Recycled semi-crystalline aliphatic polyamide PA2 granules are dissolved in a mixture of HFIP (CAS RN 920-66-1) / CH2C12 (CAS RN 75-09-3) and then a non-solvent (methanol CAS RN 67-56-1) is added. The lower molar masses are thus solubilized and the higher molar masses precipitate.

[0106] This solution is filtered at 200 pm before analysis.

[0107] The oligomers are evaluated as lactam 12 equivalents by reversed-phase liquid chromatography coupled with mass spectrometry using positive ionization by electrobulb. Formic acid is added to enhance ionization.

[0108] A peak distribution is observed because of the different molar masses (from monomer to pentamer with linear or cyclic forms).

[0109] The polyamide, by means of fluid transport on the one hand and when it is washed on the other hand, presents fewer oligomers than the same virgin semi-crystalline aliphatic polyamide because said transport and washing extract the cyclic oligomers.

[0110] Advantageously, said recycled semi-crystalline aliphatic polyamide PA2 comprises a level of cyclic oligomers, selected from oligomers having a molar mass of less than 1000 g / mol, of less than 90% by weight, in particular less than 50% by weight, in particular less than 20% by weight, in particular less than 10% by weight, compared to that of the equivalent virgin polyamide.

[0111] Advantageously, said recycled semi-crystalline aliphatic polyamide PA2 comprises a higher linear oligomer content than virgin PA.

[0112] The weight content of cyclic oligomer in a virgin polyamide is between 500 and 10,000 ppm for each cyclic species from monomer to pentamer (preferably having a mass less than 1000 gmol-1), the cyclic dimer being in particular the major species.

[0113] In particular, the cyclic oligomer content with a mass of less than 1000 gmol-1 is at most 4% by weight in the virgin polyamide.

[0114] In one embodiment, said recycled semi-crystalline aliphatic polyamide PA2 comprises a level of cyclic oligomers having a molar mass of less than 1000 g / mol, ranging from 50 to 5,000 ppm for each cyclic species from monomer to pentamer, but in any case, it is less than that of the equivalent virgin polyamide.

[0115] The linear oligomer content by weight in a virgin polyamide is from 200 to 2,000 ppm for each linear species from monomer to pentamer (preferably having a mass less than 1000 gmol-1).

[0116] In one embodiment, said recycled semi-crystalline aliphatic polyamide PA2 comprises a proportion of linear oligomers having a molar mass of less than 1000 g / mol, ranging from 250 to 5000 ppm for each cyclic species from monomer to pentamer, but in any case, it is higher than that of the equivalent virgin polyamide.

[0117] In one embodiment, said recycled semi-crystalline aliphatic polyamide PA2 comprises a weight content of alkyl chain ends ranging from 1 ppm to 5000 ppm, advantageously from 10 to 2500 ppm, said alkyl being C18-Cl and said content being superior to that of a virgin semi-crystalline aliphatic polyamide. Regarding the composition

[0118] In a first embodiment, the extrusion composition according to the invention comprises by weight:

[0119] a) from 35 to 100%, in particular from 35 to 96.9 of at least one semi-crystalline aliphatic polyamide PA1 comprising at least 30%, in particular at least 50% of recycled semi-crystalline aliphatic polyamide PA2 from used or end-of-life pipelines from offshore or onshore oil or gas fields, in particular offshore, said recycled semi-crystalline aliphatic polyamide PA2 having undergone a washing and / or compounding step after removal and grinding into granules of said pipeline;

[0120] b) from 0 to 65%, in particular 0 to 10% of at least one reinforcing fiber;

[0121] c) from 0 to 40%, in particular from 3 to 30% of at least one shock modifier;

[0122] d) from 0 to 30%, in particular 0 to 15% of a charge,

[0123] e) from 0 to 10%, in particular from 0.1 to 5% of at least one additive,

[0124] the sum of the components a + b + c + d + e is equal to 100%.

[0125] Said composition is a composition for extrusion and is not a composition for injection, that is to say it is not a molding composition.

[0126] In one embodiment of this first variant, said extrusion composition according to the invention comprises by weight:

[0127] a) from 35 to 97%, in particular from 35 to 96.9 of at least one semi-crystalline aliphatic polyamide PA1 comprising at least 30%, in particular at least 50% of recycled semi-crystalline aliphatic polyamide PA2 from used or end-of-life pipelines from offshore or onshore oil or gas fields, in particular offshore, said recycled semi-crystalline aliphatic polyamide PA2 having undergone a washing and / or compounding step after removal and grinding into granules of said pipeline;

[0128] b) from 0 to 65%, in particular 0 to 10% of at least one reinforcing fibre;

[0129] c) from 3 to 30% of at least one shock modifier;

[0130] d) from 0 to 30%, in particular 0 to 15% of a charge,

[0131] e) from 0 to 10%, in particular from 0.1 to 5% of at least one additive,

[0132] the sum of the components a + b + c + d + e is equal to 100%.

[0133] In another embodiment of this first variant, said composition The extrusion according to the invention comprises by weight:

[0134] a) from 35 to 96.9 of at least one semi-crystalline aliphatic polyamide PA1 comprising at least 30%, in particular at least 50%, of recycled semi-crystalline aliphatic polyamide PA2 from used or end-of-life pipelines from offshore or onshore oil or gas fields, in particular offshore, said polyamide aliphatic polyamide recycled semi-crystalline phatic PA2 having undergone a washing and / or compounding step after removal and grinding into granules of said pipe;

[0135] b) from 0 to 65%, in particular 0 to 10% of at least one reinforcing fibre;

[0136] c) from 3 to 30% of at least one shock modifier;

[0137] d) from 0 to 30%, in particular 0 to 15% of a charge,

[0138] e) from 0.1 to 5% of at least one additive,

[0139] the sum of the components a + b + c + d + e is equal to 100%.

[0140] Advantageously, in this first variant and its two embodiments, said composition consists of said constituents.

[0141] In a second embodiment, said extrusion composition comprises by weight:

[0142] a) from 35 to 100%, in particular from 35 to 96.9%, of at least one aliphatic polyamide semi-crystalline PA1 comprising at least 30%, in particular at least 50% of recycled semi-crystalline aliphatic polyamide PA2 from used or end-of-life pipelines from offshore or onshore oil or gas fields, in particular offshore, said recycled semi-crystalline aliphatic polyamide PA2 having undergone a washing and / or compounding step after removal and grinding into granules of said pipeline;

[0143] c) from 0 to 40%, in particular from 3 to 30% of at least one shock modifier;

[0144] d) from 0 to 30%, in particular 0 to 15% of a charge,

[0145] e) from 0 to 10%, in particular from 0.1 to 5% of at least one additive,

[0146] the sum of the components a + c + d + e is equal to 100%.

[0147] In one embodiment of this second variant, the reinforcing fibers are excluded from said extrusion composition according to the invention.

[0148] In one embodiment of this second variant, said extrusion composition according to the invention comprises by weight:

[0149] a) from 35 to 97 of at least one semi-crystalline aliphatic polyamide PA1 comprising at least 30%, in particular at least 50% of recycled semi-crystalline aliphatic polyamide PA2 from used or end-of-life pipelines from offshore or onshore oil or gas fields, in particular offshore, said recycled semi-crystalline aliphatic polyamide PA2 having undergone a washing and / or compounding step after removal and grinding into granules of said pipeline;

[0150] c) from 3 to 30% of at least one shock modifier;

[0151] d) from 0 to 30%, in particular 0 to 15% of a charge,

[0152] e) from 0 to 10%, in particular from 0.1 to 5% of at least one additive,

[0153] the sum of the components a + b + c + d + e is equal to 100%.

[0154] In another embodiment of this second variant, said extrusion composition according to the invention comprises by weight:

[0155] a) from 35 to 96.9 of at least one semi-crystalline aliphatic polyamide PA1 comprising at least 30%, in particular at least 50% of recycled semi-crystalline aliphatic polyamide PA2 from used or end-of-life oil or gas pipelines from offshore or onshore oil or gas fields, in particular offshore, said recycled semi-crystalline aliphatic polyamide PA2 having undergone a washing and / or compounding step after removal and grinding into granules of said pipeline;

[0156] c) from 3 to 30% of at least one shock modifier;

[0157] d) from 0 to 30%, in particular 0 to 15% of a charge,

[0158] e) from 0.1 to 5% of at least one additive,

[0159] the sum of the components a + b + c + d + e is equal to 100%.

[0160] Advantageously, in this second variant and its two embodiments, said composition consists of said constituents.

[0161] In an embodiment of these two variants and associated embodiments thereof, said extrusion composition defined above, has a characteristic odor comprising sulfur and / or hydrocarbon and / or aromatic poles according to the description of the field of odors ® by Jean-Noel Jaubert.

[0162] In one embodiment of these two variants and associated embodiments thereof,

[0163] said semi-crystalline aliphatic polyamide PA1 comprises at least 40% recycled semi-crystalline aliphatic polyamide PA2 from used or end-of-life pipelines from offshore or onshore oil or gas fields, particularly offshore.

[0164] Advantageously, said semi-crystalline aliphatic polyamide PA1 comprises at least 50% of said recycled semi-crystalline aliphatic polyamide PA2.

[0165] Advantageously, said semi-crystalline aliphatic polyamide PA1 comprises at least 60% of said recycled semi-crystalline aliphatic polyamide PA2.

[0166] Advantageously, said semi-crystalline aliphatic polyamide PA1 comprises at least 70% of said recycled semi-crystalline aliphatic polyamide PA2.

[0167] Advantageously, said semi-crystalline aliphatic polyamide PA1 comprises at least 80% of said recycled semi-crystalline aliphatic polyamide PA2.

[0168] Advantageously, said semi-crystalline aliphatic polyamide PA1 comprises at least 90% of said recycled semi-crystalline aliphatic polyamide PA2.

[0169] In these last six embodiments, said semi-crystalline aliphatic polyamide PA1 is made up of said semi-crystalline aliphatic polyamide PA2 in the proportions described. Regarding reinforcing fibers (b)

[0170] Regarding the reinforcing fibers, these are short fibers, in particular fibers of mineral, organic or vegetable origin.

[0171] Said reinforcing fibre may be coated or uncoated.

[0172] Said reinforcing fibre may therefore comprise up to 0.1% by weight of a material of an organic nature (such as thermosetting resin or thermoplastic) called sizing.

[0173] Examples of mineral-based fibers include carbon fibers, glass fibers, basalt fibers or basalt-based fibers, silica fibers, and silicon carbide fibers. Examples of organic-based fibers include thermoplastic or thermosetting polymer-based fibers, such as semi-aromatic polyamide fibers, aramid fibers, or polyolefin fibers. Preferably, these fibers are based on an amorphous thermoplastic polymer and have a glass transition temperature (Tg) higher than the Tg of the thermoplastic polymer or polymer blend constituting the pre-impregnation matrix when the latter is amorphous, or higher than the Tf of the thermoplastic polymer or polymer blend constituting the pre-impregnation matrix when the latter is semi-crystalline.Among the plant-based fibers, we can mention natural fibers made from flax, hemp, lignin, bamboo, silk (particularly spider silk), sisal, and other cellulosic fibers, especially viscose. These plant-based fibers can be used pure, treated, or coated with a layer of coating to facilitate adhesion and impregnation of the thermoplastic polymer matrix.

[0174] Preferably said reinforcing fiber is selected from glass fibers, carbon fibers, basalt fibers and basalt-based fibers.

[0175] More advantageously, said reinforcing fibre is selected from carbon fibre and glass fibre.

[0176] In one embodiment, the reinforcing fibers present in a) are glass fibers.

[0177] Glass fibers can be circular or non-circular in cross-section.

[0178] A fiber with a circular cross-section is defined as a fiber having at every point of its circumference a distance equal to the center of the fiber and therefore represents a perfect or almost perfect circle.

[0179] Any glass fiber not exhibiting this perfect or almost perfect circle is therefore defined as a fiber with a non-circular cross-section.

[0180] Examples of non-circular cross-section fibers, without being limited to these, are non-circular fibers, for example having an elliptical, oval or cocoon shape, star fibers, flake fibers, flat fibers, cruciform fibers, a polygon and a ring.

[0181] Fiberglass can be:

[0182] - either with a circular cross-section of diameter between 4 pm and 25 pm, preferably from 4 to 3 pm.

[0183] - either with a non-circular cross-section with an L / D ratio (L representing the largest dimension of the cross-section of the fiber and D the smallest dimension of the cross-section of said fiber) between 2 and 8, in particular from 2 to 4. L and D can be measured by scanning electron microscopy (SEM).

[0184] Advantageously, glass fibers are circular.

[0185] Glass fibers are in particular of type E, R, S2, or T. Advantageously the glass fibers are of type E. Regarding the shock modifier (c):

[0186] The shock modifier is present from 0 to 40%, in particular from 3 to 30% of at least one shock modifier.

[0187] In one embodiment, it is present from 5 to 20%.

[0188] By way of example, impact modifiers are polyolefins having a modulus < 200 MPa, in particular < 100 MPa, as measured according to ISO 178:2010, at 23°C or a thermoplastic elastomer.

[0189] In one embodiment, the shock modifier is chosen from a polyolefin having a modulus < 200 MPa, in particular < 100 MPa, functionalized or not, and mixtures thereof. Polyolefin:

[0190] It may be functionalized or non-functionalized or a mixture of both.

[0191] For simplicity, the polyolefin has been designated by (B) and functionalized polyolefins (B1) and non-functionalized polyolefins (B2) have been described below.

[0192] A non-functionalized polyolefin (B2) is classically a homopolymer or copolymer of alpha olefins or diolefins, such as, for example, ethylene, propylene, 1-butene, 1-octene, butadiene. Examples include:

[0193] - homopolymers and copolymers of polyethylene, in particular LDPE, HDPE, LLDPE (linear low density polyethylene), VLDPE (very low density polyethylene) and metallocene polyethylene.

[0194] -homopolymers or copolymers of propylene.

[0195] - ethylene / alpha-olefin copolymers such as ethylene / propylene, EPRs (abbreviation for ethylene-propylene-rubber) and ethylene / propylene / diene (EPDM),

[0196] - copolymers of ethylene with at least one product selected from the salts or the esters of unsaturated carboxylic acids such as alkyl (meth)acrylate (e.g. methyl acrylate), or vinyl esters of saturated carboxylic acids such as vinyl acetate (EVA), the proportion of comonomer can reach 40% by weight.

[0197] The functionalized polyolefin (Bl) may be a polymer of alpha olefins having Reactive motifs (functionalities); such reactive motifs are acid, anhydride, or epoxy functionalities. For example, the previous polyolefins (B2) may be grafted or co- or ter-polymerized with unsaturated epoxides such as glycidyl (meth)acrylate, or with carboxylic acids or their corresponding salts or esters such as (meth)acrylic acid (which can be totally or partially neutralized by metals such as Zn, etc.) or with carboxylic acid anhydrides such as maleic anhydride. A functionalized polyolefin is, for example, a PE / EPR mixture, the weight ratio of which can vary widely, for example, between 40 / 60 and 90 / 10, this mixture being co-grafted with an anhydride, particularly maleic anhydride, at a grafting rate, for example, of 0.01 to 5% by weight.

[0198] The functionalized polyolefin (Bl) can be selected from the following (co)polymers, grafted with maleic anhydride or glycidyl methacrylate, in which the grafting ratio is, for example, from 0.01 to 5% by weight:

[0199] - PE, PP, copolymers of ethylene with propylene, butene, hexene, or octene containing, for example, 35 to 80% by weight of ethylene;

[0200] - ethylene / alpha-olefin copolymers such as ethylene / propylene, EPR (abbreviation for ethylene-propylene-rubber) and ethylene / propylene / diene (EPDM).

[0201] - styrene / ethylene-butene / styrene block copolymers (SEBS), styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), styrene / ethylene-propylene / styrene (SEPS).

[0202] - ethylene and vinyl acetate (EVA) copolymers, containing up to 40% in weight of vinyl acetate;

[0203] - ethylene and alkyl (meth)acrylate copolymers, containing up to 40% in weight of alkyl (meth)acrylate;

[0204] - ethylene and vinyl acetate (EVA) and alkyl (meth)acrylate copolymers, containing up to 40% by weight of comonomers.

[0205] The functionalized polyolefin (Bl) can also be selected from ethylene / propylene copolymers major in propylene grafted with maleic anhydride and then condensed with mono-amino polyamide (or a polyamide oligomer) (products described in EP-A-0342066).

[0206] The functionalized polyolefin (Bl) may also be a co- or ter polymer of at least the following motifs: (1) ethylene, (2) alkyl (meth)acrylate or saturated carboxylic acid vinyl ester and (3) anhydride such as maleic anhydride or (meth)acrylic acid or epoxy such as glycidyl (meth)acrylate.

[0207] By way of example of functionalized polyolefins of this latter type, the following copolymers may be cited, where ethylene preferably represents at least 60% by weight and where the ter monomer (the function) represents, for example, from 0.1 to 10% by weight of the co- polymer:

[0208] - ethylene / alkyl (meth)acrylate / (meth)acrylic acid copolymers or maleic anhydride or glycidyl methacrylate;

[0209] - ethylene / vinyl acetate / maleic anhydride or methacrylate copolymers glycidyl;

[0210] - ethylene / vinyl acetate or alkyl (meth)acrylate / acid copolymers (meth)acrylic or maleic anhydride or glycidyl methacrylate.

[0211] In the preceding copolymers, (meth)acrylic acid can be salified with Zn or Li.

[0212] The term "alkyl (meth)acrylate" in (B1) or (B2) refers to methyl acrylates and alkyl acrylates in Cl to C8, and may be selected from methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, ethyl-2-hexyl acrylate, cyclohexyl acrylate, methyl methacrylate and ethyl methacrylate.

[0213] Furthermore, the aforementioned polyolefins (B 1) can also be crosslinked by any suitable process or agent (diepoxy, diacid, peroxide, etc.); the term functionalized polyolefin also includes mixtures of the aforementioned polyolefins with a difunctional reagent such as a diacid, dianhydride, diepoxy, etc. capable of reacting with them or mixtures of at least two functionalized polyolefins capable of reacting with each other.

[0214] The copolymers mentioned above, (Bl) and (B2), can be copolymerized statistically or sequentially and exhibit a linear or branched structure.

[0215] The molecular weight, MFI, and density of these polyolefins can also vary considerably, a fact that those skilled in the art will appreciate. MFI, short for Melt Flow Index, is the melt flow index. It is measured according to ISO 1133 at 235°C under 5 kg.

[0216] Advantageously, unfunctionalized polyolefins (B2) are selected from homopolymers or copolymers of polypropylene and any homopolymer of ethylene or copolymer of ethylene and a higher alpha-olefin comonomer such as butene, hexene, octene, or 4-methyl-1-pentene. Examples include PP, high-density PE, medium-density PE, linear low-density PE, low-density PE, and ultra-low-density PE. These polyethylenes are known to those skilled in the art to be produced by a "radical" process, by Ziegler-type catalysis, or, more recently, by so-called "metallocene" catalysis.

[0217] Advantageously, functionalized polyolefins (Bl) are selected from any polymer comprising alpha olefin motifs and motifs bearing polar reactive functions such as epoxy, carboxylic acid, or carboxylic acid anhydride functions. Examples of such polymers include the polymers of Ethylene, alkyl acrylate, and maleic anhydride or glycidyl methacrylate, such as Lotader® (SK functional polymer), or polyolefins grafted with maleic anhydride, such as Orevac® (SK functional polymer), as well as terpolymers of ethylene, alkyl acrylate, and (meth)acrylic acid. Also noteworthy are homopolymers or copolymers of polypropylene grafted with a carboxylic acid anhydride and then condensed with polyamides or monoamino oligomers of polyamide.

[0218] In one embodiment, the polyolefin is cross-linked.

[0219] In another embodiment, the polyolefin is a mechanical blend of a polyethylene or polypropylene matrix thermoplastic olefinic polymer and an elastomer, vulcanized such as a vulcanized PP / EPDM blend.

[0220] The thermoplastic elastomer is a block copolymer (ether-amide block copolymer: PEBA), an ether-ester block copolymer, a polyurethane thermoplastic: TPU, a styrenic elastomer thermoplastic) Regarding the filler (d):

[0221] The charge is present from 0 to 30%, in particular 0 to 15% of a charge.

[0222] In one embodiment, the charge is present from 1 to 5%.

[0223] By way of example, the fillers may be chosen from silica, graphite, expanded graphite, carbon black, kaolin, magnesia, slag, talc, wol-lastonite, nanofillers (carbon nanotubes), pigments, metal oxides (titanium oxide), metals, advantageously wollastonite and talc, preferably talc or carbon black. Regarding additives (e)

[0224] The additive is optional and ranges from 0 to 10.0%, in particular from 0.1 to 5.0% by weight.

[0225] The additive is selected from colorants, stabilizers, plasticizers, tensor- active ingredients, nucleating agents, pigments, brighteners, antioxidants, lubricants, flame retardants, natural waxes, chain extenders and their mixtures.

[0226] Advantageously, the additive is selected from colorants, stabilizers, plasticizers, surfactants, nucleating agents, pigments, brighteners, antioxidants, flame retardants, natural waxes, chain extenders and mixtures thereof.

[0227] More advantageously, the additive is chosen from colorants, stabilizers, plasticizers, surfactants, nucleating agents, pigments, brighteners, antioxidants, natural waxes, chain extenders and mixtures thereof.

[0228] By way of example, the stabilizer may be a UV stabilizer, an organic stabilizer or more generally a combination of organic stabilizers, such as an antioxidant Phenolic stabilizers (such as those found in Ciba-BASF's Irganox® 245, 1098, or 1010), phosphite-type antioxidants (such as Ciba-BASF's Irgafos® 126), and potentially other stabilizers like a HALS (Hindered Amine Light Stabilizer, such as Ciba-BASF's Tinuvin® 770), a UV filter (such as Ciba's Tinuvin® 312), or a phosphorus-based stabilizer can be used. Amine-type antioxidants like Crompton's Naugard® 445 or multifunctional stabilizers like Clariant's Nylostab® S-EED can also be used.

[0229] This stabilizer can also be a mineral stabilizer, such as a copper-based stabilizer. Examples of such mineral stabilizers include copper halides and copper acetates. Other metals, such as silver, could also be considered, but these are known to be less effective. These copper-based compounds are typically associated with alkali metal halides, particularly potassium.

[0230] By way of example, plasticizers are selected from benzene sulfonamide derivatives, such as n-butyl benzene sulfonamide (BBSA); ethyl toluene sulfonamide or N-cyclohexyl toluene sulfonamide; esters of hydroxybenzoic acids, such as ethyl-2-hexyl parahydroxybenzoate and decyl-2-hexyl parahydroxybenzoate; esters or ethers of tetrahydrofurfuryl alcohol, such as oligoethyleneoxytetrahydrofurfuryl alcohol; and esters of citric acid or hydroxymalonic acid, such as oligoethyleneoxy malonate.

[0231] We would not depart from the scope of the invention by using a mixture of plasticizers.

[0232] In one embodiment, the composition according to the invention contains less than 5% advantageously less than 2% of plasticizer.

[0233] In another embodiment, the composition has an MFI measured according to ISO 1133 at 235°C under 5Kg ranging from 0.5 to 25.

[0234] According to another aspect, the present invention relates to a process for preparing a recycled semi-crystalline aliphatic polyamide as defined above, characterized in that it comprises, after removal and grinding into granules of used or end-of-life pipe from oil or gas field exploitation platforms under the sea or on land, in particular under the sea, a washing and / or compounding step of said semi-crystalline aliphatic polyamide PA2.

[0235] According to another aspect, the present invention relates to the use of a composition as defined above, to prepare articles obtained by extrusion.

[0236] According to yet another aspect, the present invention relates to a method for preparing a single-layer or multi-layer pipe, characterized in that it comprises an extrusion step of a composition as defined above. Description of the figures

[0237] [Fig.1] presents the field of odors® by Jean-Noel Jaubert

[0238] The meaning of the abbreviations used in [Fig.1] is shown in Table 1.

[0239] [Tables 1] AB= Am-brettolide® AC= Cynnamyl alcohol AM= Isobutylamine AN= Methylanthralylate AP= Phenethyl alcohol AX= Ambroxan® BA= Benzaldehyde BE= Ethylisobutyrate BU= Butyric acid BZ= Benzyl acetate CA= Calone® CD= Cinnamaldehyde CI= Citral CL= Hypochlorite CM= Camphor CO= Coumarin CR= 3-caryophyllene CY= Methyl salicylate DC= γ-undecanolactone DI= Diacetyl EG= Eugenol EM= Ethylmaltol EV= Evenyl GE= Geosmin HX= cis-3-hexenol LM= d-limonene LN= Linalool ME= 1-menthol MT= Methional NO= Nonanal OC= 1-octen-3-ol OL= trans-anethole PA= Ethylphenyl acetate PB= p-hydroxyphenylbutanone PH= Phenom PI = α-pinene PN = cyclopentanone PY = 2-acetylpyrazine QU = Isobutylquinoline SA = Diallyl disulfide SC = Skatole SM = dimethyl disulfide TE = Terpinyl acetate TH = Thymol VA = Vanillin VE = Vetiveryl acetate

[0240] EXAMPLES

[0241] The invention will now be described in more detail with the help of the following examples, which are not limiting.

[0242] The different compositions used for the preparation of the tubes of the invention are as follows:

[0243] Virgin PA11 1= PA11 of Mn 28,000 g / mol + 13% BBSA + 1% thermal stabilizer (consisting of 0.7% Lowinox® 44B25 phenol from the company Great Lakes, 0.3% phosphite Irgafos® 168 from the company Ciba).

[0244] Virgin PA11 2 = PA11 of Mn 28,000 g / mol + 1% thermal stabilizer (consisting of 0.7% of Lowinox® 44B25 phenol from Great Lakes, 0.3% of Irgafos® 168 phosphite from Ciba).

[0245] Virgin PA12 1= PA12 of Mn 26,000 g / mol + 13% BBSA + 1% thermal stabilizer (consisting of 0.7% Lowinox® 44B25 phenol from Great Lakes, 0.3% Irgafos® 168 phosphite from Ciba).

[0246] PA11 Recy 1 = composition consisting of 100% virgin PA11 1 as described above, derived from offshore pipe crushed into particles ranging in size from 0.5mm to 25mm.

[0247] PA11 Recy2 = composition consisting of 100% virgin PA11 1 described above, from offshore pipe ground into particles of size from 0.5mm to 25mm then washed with methanol by dissolution reprecipitation.

[0248] PA11 recy3= composition consisting of 50% virgin PA11 1 described above, from offshore pipe ground into particles of size from 0.5mm to 25mm then washed with methanol by dissolution reprecipitation then compounded under vacuum with 50% virgin PA 11 2 without BBSA.

[0249] PA11 recy4= composition consisting of 90% virgin PA11 1 described above, from offshore pipe ground into particles of size from 0.5mm to 25mm then washed with methanol by dissolution reprecipitation then compounded with 10% virgin PA11 2, 0.5% antioxidants (consisting of 0.35% Lowinox® 44B25 phenol from Great Lakes, 0.15% Irgafos® 168 phosphite from Ciba) and addition of 600 ppm catalyst (H3PO4).

[0250] PA12 recy 5= composition consisting of 70% virgin PA12 1 from offshore pipe ground into particles of size from 0.5mm to 25mm then washed with methanol by dissolution reprecipitation then compounded with 20% virgin PA12 2, 10% shock modifier Orevac® IM800 marketed by SK FP, 0.5% antioxidants (consisting of 0.35% Lowinox® 44B25 phenol from Great Lakes, 0.15% Irgafos® 168 phosphite from Ciba) and addition of 600 ppm catalyst (H3PO4).

[0251] The PA11 recy3 composition was prepared by conventional compounding in a Coperion® 40 type co-rotating twin-screw extruder, 70 kgh, at 300 rpm, at 270°C with a strong degassing of -660 mmHg

[0252] The PA11 recy4 composition was prepared by a conventional compounding in a Coperion® 40 type co-rotating twin screw extruder, 70kgh, at 300rpm, at 270° with direct addition of catalyst of 600 ppm of H3PO4.

[0253] The PA12 recy5 composition was prepared by conventional compounding in a Coperion® 40 type co-rotating twin screw extruder, 70kgh, at 300rpm, at 270°C with direct addition of catalyst of 600 ppm of H3PO4.

[0254] Extruded plates:

[0255] Two types of plates are produced: - A-plates, 250mm wide, 5.5mm thick and 1m long - B-plates, 250mm wide, 1mm thick and 1m long

[0256] Before testing, to ensure the best plate properties and good extrusion quality, it is verified that the extruded material has a residual moisture content before extrusion of less than 0.08%. If this is not the case, an additional drying step is carried out on the material before testing, generally in a vacuum dryer, overnight at 80°C.

[0257] To produce the two types of plates, a Maillefer extruder with a screw diameter of 60 mm and a length of 24D is used, where D is the screw diameter. No filtration system is used at the end of the screw. The extruder feeds a 280 mm Yvroud die with an 8 mm air gap to produce plates A, and a 280 mm Yvroud die with a 3 mm air gap to produce plates B. The screw speed is adjusted according to the sample geometry, the calendering speed, and the drawing speed. The temperature of the three cooling cylinders varies between 80°C and 60°C depending on the fluidity of the products.

[0258] The plates, which meet the characteristics described in this patent application, were taken, after stabilization of the extrusion parameters, the dimensions of the plates no longer evolving over time.

[0259] In general, the temperatures of the extruders and tooling (head, fitting and die) must be set so as to be sufficiently higher than the melting temperature of the compositions in question, so that they remain in a molten state, thus preventing them from solidifying and blocking the machine.

[0260] The plates produced by extrusion described above were then evaluated on several criteria:

[0261] The results are shown in Table 2.

[0262] [Tables2] Sample s Exudation after extrusion IR thermoforming Heating time required EC1 Virgin PAU 1 Strong (4)(BBSA) 2'20" EC2 Virgin PAU 2 Weak (1) 2'20" EC3 Virgin PA12 1 Strong (4) (BBSA) 2'20" EC4 PA 11 Recyl very strong (5) (petroleum residues) 1'10" eu PA 11 Recy2 Weak (1) 1'25" EI2 PA 11 Recy3 Weak (1) 1'50" EI3 PA 11 Recy4 Weak (1) 1'15" EI4 PA 12 Recy5 Weak (1) 1'30"

[0263] Exudation is determined on 1 mm plates which are placed for 7 days at 70°C and 62% RH (relative humidity).

[0264] Exudation is manifested by the appearance of a deposit on the surface and is estimated visually.

[0265] The plaques are rated from 1 (little exudation) to 5 (a lot of exudation) by trained personnel.

[0266] Thermoforming is performed on a 5.5 mm thick and 220 mm wide plate obtained after cutting extruded sheets on a KIEFEL KD 20 / 25 machine. A "yogurt pot" type mold with vertical walls 40 mm high and 60 mm in diameter was used. The heating system includes two infrared heating plates (upper and lower) to ensure even heating. The heating power is set to 100%. The forming time is 1 second. A pressure of 4 bar is applied to obtain good thermoforming. The heating times to obtain a Sufficient thermoforming temperatures are listed in the table above. The compositions of the invention offer the best compromise between exudation and heating time. In particular, the heating time of the compositions of the invention is shorter than that of the comparative compositions EC1, EC2, and EC3, and the exudation of the compositions of the invention is lower than that of the comparative compositions EC1, EC3, and EC4.

Claims

Demands

1. Extrusion composition comprising by weight: a) from 35 to 100%, in particular from 35 to 96.9%, of at least one semi-crystalline aliphatic polyamide PA1 comprising at least 30%, in particular at least 50%, of recycled semi-crystalline aliphatic polyamide PA2 from used or end-of-life pipelines from subsea or onshore, in particular subsea, oil or gas fields, said recycled semi-crystalline aliphatic polyamide PA2 having undergone a washing and / or compounding step after removal and grinding into granules from said pipeline and said recycled semi-crystalline aliphatic polyamide PA2 comprising at least one species selected from sulfur compounds, alkanes, C14-C18 aliphatic monoacids, mono- or poly-aromatic compounds and aromatic acids; b) from 0 to 65%, in particular 0 to 10% of at least one reinforcing fiber; c) from 0 to 40%, in particular 3 to 30% of at least one shock modifier;d) from 0 to 30%, in particular 0 to 15% of a filler, e) from 0 to 10%, in particular from 0.1 to 5% of at least one additive, the sum of components a + b + c + d + e equals 100%, the inherent viscosity of said composition, as determined according to ISO 307:2007 in m-cresol at 20°C being greater than or equal to 1.2 dl / g, in particular from 1.2 dl / g to 1.7 dl / g.;

2. Extrusion composition according to claim 1, characterized in that the recycled semi-crystalline aliphatic polyamide PA2 is a long-chain polyamide having an average number of carbon atoms per nitrogen atom greater than 7, in particular greater than 9.

3. Extrusion composition according to any one of claims 1 to 2, characterized in that said recycled semi-crystalline aliphatic polyamide PA2 comprises at least one species selected from alkanes, C14-C18 aliphatic mono-acids, mono- or poly-aromatic compounds and aromatic acids.

4. Extrusion composition according to any one of claims 1 to 3, characterized in that said recycled semi-crystalline aliphatic polyamide PA2 comprises at least one species selected from alkanes, mono- or poly-aromatic compounds and aromatic acids.

5. Extrusion composition according to any one of claims 1 to 4, characterized in that said recycled semi-crystalline aliphatic polyamide PA2 comprises at least one species selected from alkanes such as methylcyclopentane, cyclohexane, methylcyclohexane, 1,2-cis-dimethylcyclohexane, 1,2-trans-dimethylcyclohexane, 1,3-cis-dimethylcyclohexane, 1,3-trans-dimethylcyclohexane, 1,4-cis-dimethylcyclohexane, 1,4-trans-dimethylcyclohexane, or ethyl cyclohexane and mono- or poly-aromatic compounds such as toluene, xylene, trimethylbenzene, methyl diphenyl and diphenyl methanol, naphthalene, 1-methylnaphthalene, 2-methylnaphthalene, 1,2-dimethylnaphthalene, 1,3-dimethylnaphthalene, 1,4-dimethylnaphthalene, 1,3,6-trimethylnaphthalene, the 2,3,5-trimethylnaphthalene, 1-phenanthrene, 2-methylphenanthrene.

6. Extrusion composition according to any one of claims 1 to 5, characterized in that the molar content of said species present in recycled semi-crystalline aliphatic polyamide PA2 is from 100 ppm to 2000 ppm, in particular from 100 ppm to 1000 ppm

7. Extrusion composition according to any one of claims 1 to 6, having a characteristic odor comprising sulfur / pyrogenized and / or hydrocarbon and / or aromatic, terpenic and phenolic poles.

8. Extrusion composition according to any one of claims 1 to 7, characterized in that the recycled semi-crystalline aliphatic polyamide PA2 has functions resulting from thermolysis reactions in acid medium, in particular amide functions and / or alpha methylene of said amide functions and acid chain ends, selected from nitrile, ketone, and ester functions resulting from reaction of the acid functions of the polyamide with alcohols used during the life of said pipes, in a molar ratio with respect to the amide functions greater than that of the same polyamide constituting an unused pipe.

9. Extrusion composition according to claim 8, characterized in that the molar ratio of functions resulting from thermolysis reactions is from 1 / 10000 to 1 / 20 as determined by proton NMR.

10. Extrusion composition according to any one of claims 1 to 9, characterized in that the recycled semi-crystalline aliphatic polyamide PA2 comprises a proportion of cyclic oligomers selected from oligomers having a molar mass less than 1000 g / mol lower than that of the equivalent virgin polyamide.

11. Extrusion composition according to any one of claims 1 to 10, characterized in that the recycled semi-crystalline aliphatic polyamide PA2 comprises an alkyl chain end content of 1 ppm to 5000 ppm, advantageously 10 to 2500 ppm, said alkyl being in C18 Cl and said level being higher than that of a virgin semi-crystalline aliphatic polyamide.

12. A process for preparing a recycled semi-crystalline aliphatic polyamide as defined in any one of claims 1 to 11, characterized in that it comprises, after removal and grinding into granules of used or end-of-life pipe from offshore or onshore oil or gas field production platforms, particularly offshore, a washing and / or compounding step of said semi-crystalline aliphatic polyamide PA2.

13. Use of a composition as defined in any one of claims 1 to 11, to prepare articles obtained by extrusion.

14. A method for preparing a single-layer or multi-layer pipe, characterized in that it comprises an extrusion step of a composition as defined in any one of claims 1 to 11.

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