Recyclable multilayer structure for fluid transport, distribution or storage applications

Abstract

The present invention relates to a recyclable multilayer structure for transporting, distributing or storing fluids, comprising, from the outside inwards: 1) an outer layer (I) made of polyamide comprising a composition comprising: a) from 41% to 100% by weight of at least one polyamide having a C / N ratio of greater than 7, b) from 0 to 10% by weight of at least one polyamide different from the preceding one having a C / N ratio of less than 10, c) from 0 to 30% by weight of at least one impact modifier, d) from 0 to 5% by weight of at least one additive, e) from 0 to 14% by weight of at least one plasticizer, the sum of the constituents a) + b) + c) +d) + e) being equal to 100% by weight; 2) a barrier layer (II) which is water-soluble at a temperature below or equal to 150°C; 3) an inner layer (III) made of polyamide comprising a composition comprising: a) from 41% to 100% by weight of at least one polyamide having a C / N ratio of greater than 7, b) from 0 to 10% by weight of at least one polyamide different from the preceding one having a C / N ratio of less than 10, c) from 0 to 30% by weight of at least one impact modifier, d) from 0 to 5% by weight of at least one additive, e) from 0 to 14% by weight of at least one plasticizer, the sum of the constituents a) + b) + c) +d) + e) being equal to 100% by weight; and / or (IV) comprising predominantly at least one polyamide of aliphatic type or consisting of more than 75% of aliphatic units.

Description

[0001] DESCRIPTION

[0002] TITLE OF THE INVENTION: RECYCLABLE MULTILAYER STRUCTURE FOR FLUID TRANSPORT, DISTRIBUTION OR STORAGE APPLICATIONS

[0003] The invention relates to recyclable multi-layer structures for fluid transportation, distribution or storage applications.

[0004] [Earlier technique]

[0005] Every year, several million motor vehicles become unusable worldwide. An end-of-life vehicle (ELV) contains numerous toxic and polluting products (liquid or solid): used oil, batteries, air conditioning fluid, explosive airbag components, etc. If handled improperly, this waste can lead to soil and water pollution, as well as accidents. ELVs are therefore considered hazardous waste.

[0006] A large number of vehicle components are salvageable and recyclable, in the form of used spare parts or raw materials. Parts intended for reuse (headlights, turn signals, engine, radiator, starter, hood, fenders, doors, etc.) are dismantled and stored for resale.

[0007] Non-recyclable carcasses and parts (ferrous and non-ferrous metals, plastics, glass, rubber, etc.) are crushed for recycling or landfill.

[0008] European Directive 2000 / 53 / EC on end-of-life vehicles has set a reuse and recovery rate of 95% by weight per vehicle from 2015.

[0009] Therefore, only 5% by weight of ultimate waste should remain, i.e. waste which cannot be treated under the technical and economic conditions of the moment and which will be incinerated or removed to specific storage centers.

[0010] The 95% by weight reused and recovered is subject to:

[0011] Energy recovery: use of waste (oils, tires, plastics, etc.) as a means of energy production, by direct incineration with or without other waste;

[0012] Material recovery: Reuse or re-employment: new use of a part which retains the same use and is not transformed, or Recycling: operation aimed at introducing materials from waste into the production cycle, in total or partial replacement of a virgin material.

[0013] A motor vehicle contains a large number of pipes, including pipes intended for the transport of fluids such as air, oil (for example for cooling the automatic gearbox "TOC, Transmission Oil Cooler), water, a urea solution, a glycol-based coolant, a fuel such as gasoline, in particular bio-gasoline or diesel, in particular bio-diesel, or hydrogen.

[0014] These pipes can be single-layer and / or multi-layer tubular structures, in particular based on polyamide(s). When the motor vehicle is out of use, some pipes present in it may be too degraded to be able to be reused as, for example, in the form of a tube, without risk or without this leading to excessively degraded usage properties.

[0015] Indeed, the tubes, particularly under the engine hood, are placed in a severe thermo-oxidative environment due to the heat released by the engine, which can typically reach 150°C, and the presence of air and therefore oxygen. Each 10°C increase in temperature typically results in a halving of the tube's lifespan, as well as the degradation of certain additives in said tubes, such as stabilizers.

[0016] Furthermore, a fuel transport pipe, for example a polyamide pipe which contains a plasticiser, has lost most of its plasticiser when it reaches the end of its life and the polyamide which initially constitutes it may be partly depolymerised and / or degraded and has lost most of its stabilisers, which prevents it from being reused without risk.

[0017] Until now, the used automotive hose is not reused and is often incinerated, but this then contributes to global warming, the reduction of which is becoming one of the major challenges of the 21st century.

[0018] Current structures with an ethylene vinyl alcohol (EVOH) barrier layer are difficult to recycle, because the PA / EVOH mixture obtained after grinding and recompounding proves to be less efficient in terms of mechanical properties compared to the expected specifications and presents a safety risk.

[0019] Indeed, after extrusion with the PA / EVOH mixture obtained, the final part presents areas of fragility (presence of cracking and incipient fracture) which presents a safety risk, particularly with fuel.

[0020] Furthermore, several car manufacturers have the more or less long-term objective of recycling 100% of the vehicles they produce in order to achieve a zero environmental impact.

[0021] In a context of sustainable development, the use of a structure with a barrier layer that is easily removable during a recycling process would therefore be of interest.

[0022] International application WO2009083525 describes PVOH as having grease and gas barrier properties but in the absence of water. Indeed, in contact with liquid water or even with water vapor in so-called tropical conditions (38°C and 90% RH), the grease and gas barrier properties of PVOH disappear. These properties will be lost if the complex is washed with a solvent capable of solubilizing the water barrier film or if the complex is used at temperatures above the melting point of the water barrier film.

[0023] To address this problem, this international application uses a PVOH having a molecular weight greater than 13,000 and a degree of hydrolysis greater than 81%, surface-grafted with a fatty acid having an aliphatic chain comprising at least 12 carbon atoms, which makes it possible to obtain a film having barrier properties to water, grease, gases and water vapor.

[0024] International application WO 2008 / 057763 describes a tube with at least five symmetrical layers of polyamide with a central layer of EVOH or PVOH to avoid problems of fragmentation of the pipe. It is stated that the thickness of the barrier layer is 210 to 280 pm.

[0025] PVOH is cited but not exemplified and nothing is indicated about its recyclable nature.

[0026] There is therefore a need to propose structures with barrier properties to gasolines such as gasoline, in particular bio-gasoline, diesel, in particular bio-diesel, or gases such as hydrogen, carbon dioxide, oxygen and nitrogen, close to those currently proposed, but with optimal recyclability not offered by structures with an EVOH barrier layer. The present invention therefore relates to a recyclable multilayer structure for the transport, distribution or storage of fluids, in particular for the distribution or storage of fluids, comprising from the outside to the inside:

[0027] 1) an outer layer (I) of polyamide, in particular aliphatic, comprising a composition comprising: a) from 41 to 100% by weight of at least one polyamide, in particular aliphatic, having a C / N ratio greater than 7, preferably greater than 8, b) from 0 to 10% by weight of at least one polyamide, in particular aliphatic, different from the previous one, having a C / N ratio less than 10, preferably less than 8, c) from 0 to 30% by weight of at least one impact modifier, d) from 0 to 5% by weight of at least one additive, e) from 0 to 14% by weight of at least one plasticizer, the sum of the constituents a) + b) + c) + d) + e) ​​being equal to 100% by weight,

[0028] 2) a water-soluble barrier layer (II) at a temperature less than or equal to 150°C, in particular less than or equal to 120°C,

[0029] 3) an inner layer:

[0030] (III) polyamide, in particular aliphatic, comprising a composition comprising: a) from 41 to 100% by weight of at least one polyamide, in particular aliphatic, having a C / N ratio greater than 7, preferably greater than 8, b) from 0 to 10% by weight of at least one polyamide, in particular aliphatic, different from the previous one, having a C / N ratio less than 10, preferably less than 8, c) from 0 to 30% by weight of at least one impact modifier, d) from 0 to 5% by weight of at least one additive, e) from 0 to 14% by weight of at least one plasticizer, the sum of the constituents a) + b) + c) + d) + e) ​​being equal to 100% by weight, and / or

[0031] (IV) comprising predominantly at least one polyamide of aliphatic type or consisting of more than 75% of aliphatic units, said aliphatic polyamide being chosen from:

[0032] - a polyamide noted A having an average number of carbon atoms per nitrogen atom noted CA of from 4 to 8.5, advantageously from 4 to 7;

[0033] - a polyamide noted B and an average number of carbon atoms per nitrogen atom noted CB of from 7 to 10, advantageously from 7.5 to 9.5;

[0034] - a polyamide denoted C having an average number of carbon atoms per nitrogen atom denoted CC of from 9 to 18, advantageously from 10 to 18; layer (IV) being adjacent to layer (II) if layer (III) is also present and layer (III) is then the innermost or layer (IV) is the innermost if layer (III) is absent.

[0035] The inventors therefore unexpectedly found that the use of a water-soluble barrier layer at a temperature less than or equal to 150°C, in particular less than or equal to 120°C, in a multilayer structure for the transport, distribution or storage of fluids made it possible not only to have structures with barrier properties close to those proposed in the prior art in EVOH, but also to be able to recycle said structure without loss of performance in terms of mechanical properties compared to the expected specifications, in particular after grinding, which structures with EVOH barriers do not offer.

[0036] In one embodiment, said aliphatic polyamide is chosen from:

[0037] - a polyamide noted B and an average number of carbon atoms per nitrogen atom noted CB of from 7 to 10, advantageously from 7.5 to 9.5;

[0038] - a polyamide noted C having an average number of carbon atoms per nitrogen atom noted CC of from 9 to 18, advantageously from 10 to 18;

[0039] The term "recyclable" means that said tubular structure after use and therefore after transport, distribution or storage of fluids, can be reused, in particular after grinding and washing with hot water, that is to say implemented in a process for manufacturing a part, in particular a new tubular structure, in particular by extrusion while obtaining good mechanical properties, in particular cold impact, a low flexural modulus, a high elongation at break, unlike the recycling of a structure comprising an EVOH layer.

[0040] Grinding is carried out according to conventional techniques of those skilled in the art to a size of 1 mm to 2 cm.

[0041] Said reuse of said used tubular structure may be carried out in a mixture or not with virgin material. The term “multi-layer structure” designates for example a tank, a pipe or tube, comprising or consisting of several layers, in particular two layers, excluding a film or a granule.

[0042] The term "fluids" means a gas or liquid used in the automobile, in particular air, oil (for example for cooling the automatic gearbox "TOC, Transmission Oil Cooler), water, a urea solution, a glycol-based coolant, or a fuel such as gasoline, in particular alcohol-based gasoline, bio-gasoline or diesel, in particular bio-diesel, or hydrogen as well as a fluid chosen from carbon dioxide, oxygen and nitrogen.

[0043] In one embodiment, said fluid designates fuels, in particular gasoline, in particular alcohol-containing gasoline, bio-gasoline or diesel, in particular bio-diesel.

[0044] In one embodiment, said fluid designates hydrogen.

[0045] Regarding the composition of the outer layer (I)

[0046] Polyamide a)

[0047] Said at least one polyamide a) of layer (I) is a polyamide, in particular aliphatic, having a C / N ratio greater than 7, preferably greater than 8.

[0048] It can be aliphatic or semi-aromatic.

[0049] Advantageously, it is aliphatic.

[0050] The nomenclature used to define polyamides is described in ISO 1874-1:2011 "Plastics - Polyamide (PA) materials for molding and extrusion - Part 1: Designation" and is well known to those skilled in the art.

[0051] The term "polyamide" according to the invention designates both a homopolyamide and a copolyamide. Advantageously, said polyamide is semi-crystalline

[0052] The expression "semi-crystalline polyamide" within the meaning of the invention throughout the description designates polyamides which have a melting temperature (Tf) and an enthalpy of fusion AH > 25 J / g, in particular > 40 J / g, in particular > 45 J / g, as well as a glass transition temperature (Tg) as determined by DSC according to ISO 11357-1:2016 and ISO 11357-2 and 3:2013, at a heating rate of 20K / min.

[0053] Said at least one polyamide when it is aliphatic is 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 Xa with at least one dicarboxylic acid Yb.

[0054] When said at least one aliphatic polyamide is obtained from the polycondensation of at least one lactam, said at least one lactam may be chosen from a C6 to C18 lactam, preferably a C10 to C18 lactam, more preferably a C10 to C12 lactam. A C6 to C12 lactam is in particular caprolactam, decanolactam, undecanolactam, and lauryllactam. When said at least one aliphatic polyamide is obtained from the polycondensation of at least one lactam, it may therefore comprise a single lactam or several lactams.

[0055] Advantageously, said at least one aliphatic polyamide is obtained from the polycondensation of a single lactam and said lactam is chosen from lauryllactam and undecanolactam, advantageously lauryllactam.

[0056] When said at least one aliphatic polyamide is obtained from the polycondensation of at least one amino acid, said at least one amino acid may be chosen from a C6 to C18 amino acid, preferably a C10 to C18 amino acid, more preferably a C10 to C12 amino acid.

[0057] 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. When said at least one aliphatic polyamide is obtained from the polycondensation of at least one amino acid, it can therefore comprise a single amino acid or several amino acids.

[0058] Advantageously, said aliphatic 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.

[0059] When said at least one aliphatic polyamide is obtained from the polycondensation of at least one C4-C36, preferably C5-C18, preferably C5-C12, more preferably C10-C12, diamine Xa with at least one C4-C36, preferably C6-C18, preferably C6-C12, more preferably C10-C12, diacid Yb, then said at least one Xa diamine is an aliphatic diamine and said at least one Yb diacid is an aliphatic diacid.

[0060] The diamine can be linear or branched. Advantageously, it is linear.

[0061] Said at least one C4-C36 diamine Xa may in particular be chosen from 1,4-butanediamine, 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethyldiamine, 1,8-octamethyldiamine, 1,9-nonamethyldiamine, 1,10-decamethyldiamine, 1,11-undecamethyldiamine, 1,12-dodecamethyldiamine, 1,13-tridecamethyldiamine, 1,14-tetradecamethyldiamine, 1,16-hexadecamethyldiamine and 1,18-octadecamethyldiamine, octadecenediamine, eicosanediamine, docosanediamine and diamines obtained from fatty acids.

[0062] Advantageously, said at least one diamine Xa is C5-C18 and chosen from 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethyldiamine, 1,8-octamethyldiamine, 1,9-nonamethyldiamine, 1,10-decamethyldiamine, 1,11-undecamethyldiamine, 1,12-dodecamethyldiamine, 1,13-tridecamethylenediamine, 1,14-tetradecamethyldiamine, 1,16-hexadecamethyldiamine and 1,18-octadecamethylenediamine. Advantageously, said at least one diamine Xa 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-undecamethylediamine, 1,12-dodecamethylediamine.

[0063] Advantageously, said at least one diamine Xa in C6 to C12 is in particular chosen from 1,6-hexamethylenediamine, 1,7-heptamethyldiamine, 1,8-octamethyldiamine, 1,9-nonamethyldiamine, 1,10-decamethylenediamine, 1,11-undecamethyldiamine, 1,12-dodecamethyldiamine.

[0064] Advantageously, the diamine Xa used is C10 to C12, in particular chosen from 1,10-decamethyldiamine, 1,11-undecamethyldiamine, 1,12-dodecamethyldiamine.

[0065] Said at least one C4 to C36 dicarboxylic acid Yb may be chosen from succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, octadecanedioic acid, and diacids obtained from fatty acids.

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

[0067] Advantageously, said at least one dicarboxylic acid Yb is C6 to C18 and is chosen from adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, octadecanedioic acid.

[0068] Advantageously, said at least one dicarboxylic acid Yb is C6 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 Yb is C10 to C12 and is chosen from sebacic acid, undecanedioic acid, dodecanedioic acid.

[0070] When said aliphatic polyamide is obtained from the polycondensation of at least one diamine Xa with at least one dicarboxylic acid Yb, it can therefore comprise a single diamine or several diamines and a single dicarboxylic acid or several dicarboxylic acids.

[0071] Advantageously, said aliphatic polyamide is obtained from the polycondensation of a single diamine Xa with a single dicarboxylic acid Yb.

[0072] In one embodiment, the aliphatic polyamide a) is chosen from PA610, PA612, PA516, PA1010, PA1012, PA1014, PA1212, PA1214, PAU, PA12.

[0073] Advantageously, it is chosen from PA612, PA516, PA1010, PA1012, PA1014, PA1212, PA1214, PAU and PA12, in particular from PAU and PA12. Said at least one semi-aromatic polyamide or polyphthalamide (PPA) may be a homopolyamide or a copolyamide.

[0074] When in homopolyamide form, it has the formula XAr or Ar'Y.

[0075] XAr denotes a unit obtained from the polycondensation of a diamine X and an aromatic dicarboxylic acid Ar, the diamine X being C6-C36, preferably C6-C18, preferably C6-C12, more preferably C10-C12.

[0076] The diamine can be linear or branched. Advantageously, it is linear.

[0077] Said at least one C6-C36 diamine X may in particular be chosen from 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, eicosanediamine, docosanediamine and diamines obtained from fatty acids.

[0078] Advantageously, said at least one diamine X is C6-C18 and chosen from 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.

[0079] Advantageously, said at least one diamine X in C6 to C12, is in particular chosen from 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine.

[0080] Advantageously, said at least one diamine X in C6 to C12, is in particular chosen from 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine.

[0081] Advantageously, the diamine X used is C10 to C12, in particular chosen from 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine.

[0082] The aromatic dicarboxylic acid being advantageously chosen from terephthalic acid (denoted T), isophthalic acid (denoted I), 2,5-furan dicarboxylic acid 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.

[0083] Ar'Y denotes a unit obtained from the polycondensation of an aromatic diamine Ar' and an aliphatic dicarboxylic acid Y, the aromatic diamine Ar' being for example chosen from MXD (metaxylylene diamine) and PXD (paraxylylene diamine). MXDY denotes a unit obtained from the polycondensation of the diamine metaxylylene diamine (MXD) and at least one aliphatic dicarboxylic acid Y.

[0084] PXDY denotes a unit obtained from the polycondensation of the diamine paraxylylene diamine (MXD) and at least one aliphatic dicarboxylic acid Y.

[0085] Said at least one C6 to C36 dicarboxylic acid Y may be chosen 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.

[0086] The diacid can be linear or branched. Advantageously, it is linear.

[0087] Advantageously, said at least one dicarboxylic acid Y is C6 to C18 and is chosen from adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, octadecanedioic acid.

[0088] Advantageously, said at least one dicarboxylic acid Y is C6 to C12 and is chosen from adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid.

[0089] Advantageously, said at least one dicarboxylic acid Y is C10 to C12 and is chosen from sebacic acid, undecanedioic acid, dodecanedioic acid.

[0090] Advantageously, said polyamide a) is aliphatic.

[0091] Polyamide b)

[0092] Said at least one polyamide b) is as defined for the polyamide a) of layer (I) with the difference that it is a polyamide having a C / N ratio of less than 10, preferably less than 8 and that it is different from that used for the polyamide of layer (I).

[0093] Advantageously, said polyamide b) is aliphatic.

[0094] In one embodiment, the polyamide a) is aliphatic and is selected from PA 410, PA510, PA610, PA412, PA512, PA612 and PA6.

[0095] Advantageously, it is chosen from PA 410, PA510, PA 612 and PA6, in particular PA6.

[0096] The shock modifier c)

[0097] The impact modifier may be present up to 30% by weight relative to the total weight of the composition of layer (I).

[0098] In one embodiment, the impact modifier is present up to 15% by weight relative to the total weight of the composition of the layer (I), in particular up to 12% by weight relative to the total weight of the composition of the layer (I). In another embodiment, the impact modifier is present from 3 to 30% by weight relative to the total weight of the composition of the layer (I), in particular from 3 to 15% by weight, especially from 3 to 12% by weight relative to the total weight of the composition of the layer (I).

[0099] 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: 2010, determined at 23°C with a relative humidity: RH50%, and a Tg of less than 0°C (measured according to standard 11357-2: 2013 at the inflection point of the DSC thermogram, at a heating rate of 20K / min), in particular a polyolefin.

[0100] 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. For simplicity, the polyolefin has been designated (B) and functionalized polyolefins (B1) and non-functionalized polyolefins (B2) have been described below.

[0101] A non-functionalized polyolefin (B2) is typically a homopolymer or copolymer of alpha olefins or diolefins, such as, for example, ethylene, propylene, butene-1, octene-1, butadiene. Examples include:

[0102] - homopolymers and copolymers of polyethylene, in particular LDPE, HDPE, LLDPE (linear low density polyethylene), VLDPE (very low density polyethylene) and metallocene polyethylene.

[0103] - homopolymers or copolymers of propylene.

[0104] - ethylene / alpha-olefin copolymers such as ethylene / propylene, EPR (abbreviation of ethylene-propylene-rubber) and ethylene / propylene / diene (EPDM).

[0105] - styrene / ethylene-butene / styrene (SEBS), styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), styrene / ethylene-propylene / styrene (SEPS) block copolymers.

[0106] - copolymers of ethylene with at least one product chosen from salts or esters of unsaturated carboxylic acids such as alkyl (meth)acrylate (for example methyl acrylate), or vinyl esters of saturated carboxylic acids such as vinyl acetate (EVA), the proportion of comonomer being able to reach 40% by weight.

[0107] The functionalized polyolefin (Bl) may be a polymer of alpha olefins having reactive units (the functionalities); such reactive units are acid, anhydride, or epoxy functions. As an example, mention may be made of the preceding polyolefins (B2) grafted or co- or terpolymerized by unsaturated epoxides such as glycidyl (meth)acrylate, or by carboxylic acids or the corresponding salts or esters such as (meth)acrylic acid (the latter being able to be neutralized totally or partially by metals such as Zn, etc.) or by carboxylic acid anhydrides such as maleic anhydride. A functionalized polyolefin is, for example, a PE / EPR blend, the weight ratio of which can vary widely, for example between 40 / 60 and 90 / 10, said blend being co-grafted with an anhydride, in particular maleic anhydride, according to a grafting rate of, for example, 0.01 to 5% by weight.

[0108] The functionalized polyolefin (Bl) can be chosen from the following (co)polymers, grafted with maleic anhydride or glycidyl methacrylate, in which the grafting rate is for example from 0.01 to 5% by weight:

[0109] - PE, PP, copolymers of ethylene with propylene, butene, hexene, or octene containing for example 35 to 80% by weight of ethylene;

[0110] - ethylene / alpha-olefin copolymers such as ethylene / propylene, EPR (abbreviation of ethylene-propylene-rubber) and ethylene / propylene / diene (EPDM).

[0111] - styrene / ethylene-butene / styrene (SEBS), styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), styrene / ethylene-propylene / styrene (SEPS) block copolymers.

[0112] - ethylene and vinyl acetate (EVA) copolymers, containing up to 40% by weight of vinyl acetate;

[0113] - ethylene and alkyl (meth)acrylate copolymers, containing up to 40% by weight of alkyl (meth)acrylate;

[0114] - ethylene vinyl acetate (EVA) and alkyl (meth)acrylate copolymers, containing up to 40% by weight of comonomers.

[0115] The functionalized polyolefin (Bl) can also be chosen from ethylene / propylene copolymers with a majority of propylene grafted with maleic anhydride then condensed with mono-amine polyamide (or a polyamide oligomer) (products described in EP-A-0342066).

[0116] The functionalized polyolefin (Bl) may also be a co- or terpolymer of at least the following units: (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.

[0117] As examples of functionalized polyolefins of the latter type, the following copolymers may be mentioned, 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 copolymer:

[0118] - ethylene / alkyl (meth)acrylate / (meth)acrylic acid or maleic anhydride or glycidyl methacrylate copolymers;

[0119] - ethylene / vinyl acetate / maleic anhydride or glycidyl methacrylate copolymers;

[0120] - ethylene / vinyl acetate or alkyl (meth)acrylate / (meth)acrylic acid or maleic anhydride or glycidyl methacrylate copolymers.

[0121] In the above copolymers, (meth)acrylic acid can be salified with Zn or Li.

[0122] The term "alkyl (meth)acrylate" in (B1) or (B2) means C1-C8 alkyl methacrylates and acrylates, and may be selected from methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, methyl methacrylate and ethyl methacrylate.

[0123] Furthermore, the above-mentioned polyolefins (Bl) can also be crosslinked by any suitable process or agent (diepoxy, diacid, peroxide, etc.); the term functionalized polyolefin also includes mixtures of the above-mentioned polyolefins with a difunctional reagent such as diacid, dianhydride, diepoxy, etc. capable of reacting with them or mixtures of at least two functionalized polyolefins capable of reacting with each other.

[0124] The above-mentioned copolymers, (B1) and (B2), can be copolymerized in a random or block manner and have a linear or branched structure.

[0125] The molecular weight, MFI index, and density of these polyolefins can also vary widely, as those skilled in the art will appreciate. MFI, short for Melt Flow Index, is the melt flow index. It is measured according to ASTM 1238.

[0126] Advantageously, the non-functionalized polyolefins (B2) are chosen from homopolymers or copolymers of polypropylene and any homopolymer of ethylene or copolymer of ethylene and a comonomer of higher alpha olefin type such as butene, hexene, octene or 4-methyl 1-pentene. Examples that may be mentioned are PP, high density PE, medium density PE, linear low density PE, low density PE, very low density PE. These polyethylenes are known to those skilled in the art as being produced according to a “radical” process, according to a “Ziegler” type catalysis or, more recently, according to a so-called “metallocene” catalysis.

[0127] Advantageously, the functionalized polyolefins (Bl) are chosen from any polymer comprising alpha olefinic units and units carrying polar reactive functions such as epoxy, carboxylic acid or carboxylic acid anhydride functions. Examples of such polymers include terpolymers 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. Homopolymers or copolymers of polypropylene grafted with a carboxylic acid anhydride and then condensed with polyamides or monoamine oligomers of polyamide may also be mentioned.

[0128] Addendum d)

[0129] The additive may be present up to 5% by weight relative to the total weight of the layer composition (I).

[0130] In one embodiment, the additive is present from 0.1 to 5% by weight relative to the total weight of the composition of the layer (I). The additives optionally used in the compositions of the invention are the conventional additives used in polyamides well known to those skilled in the art and are in particular described in EP 2098580.

[0131] For example, they are selected from a catalyst, an antioxidant, a heat stabilizer, a UV absorber, a light stabilizer, a lubricant, an inorganic filler, a flame retardant, a nucleating agent, a colorant, reinforcing fibers, a wax and mixtures thereof.

[0132] The term "catalyst" refers to a polycondensation catalyst such as a mineral or organic acid.

[0133] Advantageously, the proportion by weight of catalyst is from approximately 50 ppm to approximately 5000 ppm, in particular from approximately 100 to approximately 3000 ppm relative to the total weight of the composition.

[0134] Advantageously, the catalyst is chosen from phosphoric acid (H3PO4), phosphorous acid (H3PO3), hypophosphorous acid (H3PO2), or a mixture thereof.

[0135] For example, the stabilizer may be a UV stabilizer, an organic stabilizer or more generally a combination of organic stabilizers, such as a phenol-type antioxidant (for example of the type of irganox® 245 or 1098 or 1010 from Ciba-BASF), a phosphite-type antioxidant (for example irgafos® 126 and irgafos® 168 from Ciba-BASF) and possibly other stabilizers such as a HALS, which stands for Hindered Amine Light Stabilizer (for example Tinuvin® 770 from Ciba-BASF), a UV stabilizer (for example Tinuvin® 312 from Ciba) or a phosphorus-based stabilizer. It is also possible to use amine-type antioxidants such as Naugard® 445 from Crompton or polyfunctional stabilizers such as Nylostab® S-EED from Clariant.

[0136] This stabilizer can also be a mineral stabilizer, such as a copper-based stabilizer. Examples of such mineral stabilizers include copper halides and acetates. Alternatively, other metals such as silver may be considered, but these are known to be less effective. These copper-based compounds are typically combined with alkali metal halides, particularly potassium.

[0137] Inorganic fillers are, for example, antistatic fillers chosen, for example, from carbon black, graphite, carbon fibers, carbon nanotubes, in particular carbon black and carbon nanotubes.

[0138] Plasticizer e)

[0139] The plasticizer may be present from 0 to 14% by weight relative to the total weight of the composition of layer (I).

[0140] The plasticizers are, for example, the plasticizers are selected from benzene sulfonamide derivatives, such as n-butyl benzene sulfonamide (BBSA); ethyl toluene sulfonamide or N-cyclohexyl toluene sulfonamide; hydroxybenzoic acid esters, such as ethyl-2-hexyl parahydroxybenzoate and decyl-2-hexyl parahydroxybenzoate; tetrahydrofurfuryl alcohol esters or ethers, such as oligoethyleneoxytetrahydrofurfuryl alcohol; and citric acid or hydroxymalonic acid esters, such as oligoethyleneoxy malonate.

[0141] It would not be outside the scope of the invention to use a mixture of plasticizers.

[0142] In one embodiment, the plasticizer is present in the composition from 1 to 14% by weight, in particular from 1 to 12% by weight relative to the total weight of the composition of layer (I).

[0143] In another embodiment, the plasticizer is present from 5 to 14%, in particular from 5 to 12% by weight relative to the total weight of the composition of the layer (I).

[0144] In one embodiment, said composition of said outer layer (I) consists of: a) from 41 to 100% by weight of at least one polyamide, in particular aliphatic having a C / N ratio greater than 7, preferably greater than 8, b) from 0 to 10% by weight of at least one aliphatic polyamide different from the previous one having a C / N ratio less than 10, preferably less than 8, c) from 0 to 30% by weight of at least one impact modifier, d) from 0 to 5% by weight of at least one additive, e) from 0 to 14% by weight of at least one plasticizer, the sum of the constituents a) + b) + c) + d) + e) ​​being equal to 100% by weight,

[0145] Regarding layer (II)

[0146] Layer (II) is a water-soluble barrier layer at a temperature less than or equal to 150°C, in particular less than or equal to 120°C.

[0147] The term "barrier" layer means that the layer has very low permeability to the transported fluids.

[0148] The term "barrier layer" means a layer which is very little permeable to fluids, in particular to fuels, in particular to alcoholic gasolines and to hydrogen, which consequently allows very little fluid, in particular fuel, in particular gasoline, in particular alcoholic gasolines in the atmosphere or hydrogen to pass through.

[0149] In particular, the expression "barrier layer" means that the proportion of fuel, in particular gasoline, in particular alcoholic gasoline, which passes into the atmosphere is less than 150 g.mm / m2.day, in particular less than 20 g.mm / m2.day as determined with a CE 10 fuel at 60°C.

[0150] Gasoline permeability measurements are determined at 60°C using a gravimetric method with CE10: isooctane / toluene / ethanol = 45 / 45 / 10 vol. % and CE85: isooctane / toluene / ethanol = 7.5 / 7.5 / 85 vol. % on plates made of a polymer material.

[0151] In particular, the term "barrier layer" means that said layer is impermeable to hydrogen at 23°C, i.e. the hydrogen permeability at 23°C is less than 500 cc.mm / m2.24h.atm at 23°C under 0% relative humidity (RH). The instantaneous permeability is zero during the induction period, then it gradually increases to an equilibrium value which corresponds to the steady-state permeability value. This value obtained in steady-state is considered to be the permeability of the material.

[0152] The expression "water-soluble at a temperature less than or equal to 150°C, in particular less than or equal to 120°C" means that the polymer of layer (II) below this temperature is soluble in water and in particular has an aqueous solubility greater than 2%, for example ranging from 2% to 100% (mass percentage of polymer in water) at this temperature or below. Ethylene vinyl alcohol (EVOH) is not a water-soluble polymer within the meaning of the invention.

[0153] In one embodiment, the aqueous solubility of said water-soluble polymer is from 5 to 20%, in particular from 10 to 20% at a temperature of from 35°C to 150°C, in particular from 35°C to 120°C, in particular from 70°C to 150°C, in particular from 70°C to 120°C.

[0154] The aqueous solution for solubilizing layer 2 may have a pH different from 7, advantageously between 1 and 12, preferably between 3 and 9.

[0155] Water-soluble polymers can be: natural polymers such as: dextrin, casein, dextran, pullulan or based on these elements, artificial polymers: cellulose ethers; synthetic polymers: vinyl: poly(vinyl alcohol) (PVAL), polyacrylamide.

[0156] In another embodiment, the water-soluble polymer is chosen from copolymers comprising the vinyl alcohol and / or vinyl acetate unit in a content greater than 50% w / w, for example greater than 70% w / w, preferably greater than 80% w / w and a polymer based on milk casein.

[0157] In a first variant of this embodiment, said water-soluble polymer is a copolymer comprising at least (i) a vinyl alcohol unit in a content greater than or equal to 50% by weight, relative to the total weight of said copolymer and (ii) an olefin unit comprising at least one heteroatom in a content less than or equal to 50% by weight, relative to the total weight of said copolymer.

[0158] According to this embodiment, the term “olefin unit comprising at least one heteroatom” means an olefin unit different from the vinyl alcohol unit.

[0159] According to this embodiment, said water-soluble polymer is thus a copolymer comprising at least (i) a vinyl alcohol unit in a content greater than or equal to 50% by weight, relative to the total weight of said copolymer and (ii) an olefin unit comprising at least one heteroatom in a content less than or equal to 50% by weight, relative to the total weight of said copolymer, with said olefin unit comprising at least one heteroatom being different from said vinyl alcohol unit. By "heteroatom" is meant an atom other than the carbon atom (C) and the hydrogen atom (H). It may in particular be a nitrogen atom (N) or an oxygen atom (O).

[0160] The olefin unit comprising at least one heteroatom may be an olefin unit comprising at least one nitrogen atom and / or one oxygen atom.

[0161] According to one embodiment, the term “olefin unit comprising at least one heteroatom” means an olefin unit different from the vinyl acetate unit.

[0162] It may in particular be an olefin unit comprising at least one, or even several, alcohol (-OH), amine (-NH2) or carboxylic acid (-COOH) functions.

[0163] According to one embodiment, the olefin unit comprising at least one heteroatom within the meaning of the invention typically comprises carbon atoms and heteroatoms in a ratio [Number of Carbon atoms] / [Number of heteroatoms] of between 1 and 10, for example of between 1.5 and 8, for example of greater than 2, for example of between 2 and 6.

[0164] According to one embodiment, it may be an olefin unit comprising at least one alcohol function, said unit being different from vinyl alcohol. It may in particular be an olefin unit comprising at least two alcohol functions. By way of example, mention may in particular be made of units derived from an alkene-diol, such as for example propene-diol units.

[0165] According to another embodiment, it may be an olefin unit comprising at least one amine function, in particular at least two amine functions, such as for example butene diamine units.

[0166] According to another embodiment, it may be an olefin unit comprising at least one carboxylic acid function, in particular at least two carboxylic acid functions.

[0167] According to another embodiment, it may be an olefin unit comprising at least one alcohol function and at least one amine function.

[0168] According to one embodiment, it may be an olefin unit comprising at least one alcohol function and at least one carboxylic acid function.

[0169] According to one embodiment, it may be an olefin unit comprising at least one amine function and at least one carboxylic acid function.

[0170] According to one embodiment, said water-soluble polymer is thus a copolymer comprising at least (i) a vinyl alcohol unit in a content greater than or equal to 50% by weight, relative to the total weight of said copolymer and (ii) an olefin unit comprising at least one heteroatom chosen from nitrogen and oxygen in a content less than or equal to 50% by weight, relative to the total weight of said copolymer, with said olefin unit comprising at least one heteroatom being different from said vinyl alcohol unit and from a vinyl acetate unit.

[0171] According to any one of the embodiments of this first variant, said copolymer may comprise said vinyl alcohol unit in a content greater than or equal to 70% by weight, advantageously greater than or equal to 85% by weight, relative to the total weight of said copolymer. According to any one of the embodiments of this first variant, said copolymer may comprise said olefin unit comprising at least one heteroatom, for example as defined above, in a content less than or equal to 30% by weight, advantageously less than or equal to 15% by weight, relative to the total weight of said copolymer.

[0172] According to any one of the embodiments, said water-soluble polymer may be a copolymer comprising at least one other unit.

[0173] It may in particular be a copolymer comprising at least (i) a vinyl alcohol unit in a content greater than or equal to 50% by weight, relative to the total weight of said copolymer, (ii) an olefin unit comprising at least one heteroatom as defined above, with said olefin unit comprising at least one heteroatom being different from said vinyl alcohol unit and from a vinyl acetate unit, and (iii) a vinyl acetate unit, with said olefin unit comprising at least one heteroatom and said vinyl acetate unit being present together in a content less than or equal to 50% by weight, relative to the total weight of said copolymer.

[0174] Preferably, according to this embodiment, said vinyl acetate unit may be present in a content of less than or equal to 20% by weight, for example less than or equal to 15% by weight, for example less than or equal to 10% by weight, for example less than or equal to 5% by weight, typically less than or equal to 1% by weight, relative to the total weight of said copolymer.

[0175] According to any one of the embodiments of this first variant, said water-soluble polymer comprises less than 10% by weight of olefin units of formula CnH2n, relative to the total weight of said copolymer.

[0176] In particular, it may comprise less than 5% by weight, in particular less than 1% by weight, of olefin units of formula CnH2n, relative to the total weight of said copolymer.

[0177] According to one embodiment, the water-soluble copolymer is devoid of olefin units of formula CnH2n.

[0178] By "olefin of formula CnH2n" is meant an olefin comprising only carbon and hydrogen atoms.

[0179] According to another embodiment, said water-soluble polymer may be a copolymer consisting of (i) a vinyl alcohol unit in a content greater than or equal to 50% by weight, relative to the total weight of said copolymer and (ii) an olefin unit comprising at least one heteroatom, for example chosen from nitrogen and oxygen, in a content less than or equal to 50% by weight, relative to the total weight of said copolymer, with said olefin unit comprising at least one heteroatom being different from said vinyl alcohol unit.

[0180] In a second variant of this embodiment (i.e. of the embodiment previously described according to which the water-soluble polymer is chosen from copolymers comprising the vinyl alcohol and / or vinyl acetate unit in a content greater than 50% w / w, for example greater than 70% w / w, preferably greater than 80% w / w and a polymer based on milk casein), said water-soluble polymer is a copolymer comprising at least one vinyl alcohol unit in a content greater than or equal to 50% by weight and one vinyl acetate unit in a content less than or equal to 50% by weight, relative to the total weight of said copolymer.

[0181] According to any one of the embodiments of this second variant, said copolymer may comprise said vinyl alcohol unit in a content greater than or equal to 70% by weight, for example greater than or equal to 80% by weight, for example greater than or equal to 90% by weight, for example greater than or equal to 95% by weight, relative to the total weight of said copolymer.

[0182] According to any one of the embodiments of this second variant, said copolymer may comprise said vinyl acetate unit in a content less than or equal to 30% by weight, for example less than or equal to 20% by weight, for example less than or equal to 10% by weight, for example less than or equal to 5% by weight, relative to the total weight of said copolymer.

[0183] According to any of the embodiments of this second variant, said water-soluble polymer may be a copolymer comprising at least one other unit.

[0184] According to any one of the embodiments of this second variant, said water-soluble polymer comprises less than 10% by weight of olefin units of formula CnH2n, relative to the total weight of said copolymer.

[0185] In particular, it may comprise less than 5% by weight, in particular less than 1% by weight, of olefin units of formula CnH2n, relative to the total weight of said copolymer.

[0186] According to one embodiment, the water-soluble copolymer is devoid of olefin units of formula CnH2n.

[0187] By "olefin of formula CnH2n" is meant an olefin comprising only carbon and hydrogen atoms.

[0188] According to another embodiment, said water-soluble polymer may be a copolymer consisting of (i) a vinyl alcohol unit in a content greater than or equal to 50% by weight and (ii) a vinyl acetate unit in a content less than or equal to 50% by weight.

[0189] The presence of heteroatoms or ratios can be determined by carbon NMR in DMSO-d6.

[0190] In another embodiment, the melting temperature (Tm) of the water-soluble polymer is from 160°C to 250°C, in particular from 165°C to 220°C.

[0191] In one embodiment, layer (II) comprises 0.1 to 30% by weight of glycerol, advantageously from 1 to 13.5% by weight, relative to the total weight of said layer (II).

[0192] In one embodiment, the water-soluble polymer comprises functions capable of reacting with polyamides and in particular carboxylic acid and primary amine functions. The Tg, Te and Tf are determined by differential scanning calorimetry (DSC) according to standard 11357-2:2013 and 11357-3:2013 respectively.

[0193] In yet another embodiment, the transformation temperature of the water-soluble polymer is from 180°C to 250°C, in particular from 190°C to 220°C.

[0194] According to one embodiment, the present invention relates to a method for manufacturing a multilayer structure as defined according to the invention, comprising at least one step of extrusion or injection of said water-soluble polymer at a temperature of from 180°C to 250°C, in particular from 190°C to 220°C.

[0195] In one embodiment, the water-soluble polymer of layer (II) is excluding Ethylene vinyl alcohol (EVOH).

[0196] According to one embodiment, the water-soluble polymer of layer (II) is other than an ethylene vinyl alcohol (EVOH).

[0197] In particular, it is known that ethylene vinyl alcohol (EVOH) is generally processed, typically extruded or injected, at temperatures below 180°C.

[0198] Regarding the inner layer

[0199] The inner layer is either a layer (III) of polyamide, in particular aliphatic, or a layer (IV) comprising mainly at least one polyamide.

[0200] In both cases, said layer (III) or (IV) is then the layer in contact with the transported fluid

[0201] The inner layer can also be a layer (IV) adjacent to a layer (III). In the latter case, layer (IV) is also adjacent to layer (II) and layer (III) is then the innermost layer. Layer (III) in the latter case is then the layer in contact with the transported fluid.

[0202] Regarding the composition of the inner layer (III) when present

[0203] Said composition of the inner layer (III) comprises: a) from 41 to 100% by weight of at least one polyamide, in particular aliphatic having a C / N ratio greater than 7, preferably greater than 8, b) from 0 to 10% by weight of at least one aliphatic polyamide different from the previous one having a C / N ratio less than 10, preferably less than 8, c) from 0 to 30% by weight of at least one impact modifier, d) from 0 to 5% by weight of at least one additive, e) from 0 to 14% by weight of at least one plasticizer, the sum of the constituents a) + b) + c) + d) + e) ​​being equal to 100% by weight.

[0204] Constituents a), b), c), d) and e) are as defined for the composition of layer (I).

[0205] Each constituent a), b), c), d) and e) of the composition of the inner layer (III) may be the same or different from that of layer (I).

[0206] In one embodiment, said composition of the inner layer (III) consists of: a) from 41 to 100% by weight of at least one polyamide, in particular aliphatic having a C / N ratio greater than 7, preferably greater than 8, b) from 0 to 10% by weight of at least one polyamide, in particular aliphatic different from the previous one having a C / N ratio less than 10, preferably less than 8, c) from 0 to 30% by weight of at least one impact modifier, d) from 0 to 5% by weight of at least one additive, e) from 0 to 14% by weight of at least one plasticizer, the sum of the constituents a) + b) + c) + d) + e) ​​being equal to 100% by weight.

[0207] In one embodiment, the plasticizer is excluded from the composition of the inner layer (III) when it is present.

[0208] Regarding the composition of the inner layer (IV) when present

[0209] It mainly comprises at least one polyamide of aliphatic type or consisting of more than 75% aliphatic units, said aliphatic polyamide being chosen from:

[0210] - a polyamide noted A having an average number of carbon atoms per nitrogen atom noted CA of from 4 to 8.5, advantageously from 4 to 7;

[0211] - a polyamide noted B and an average number of carbon atoms per nitrogen atom noted CB of from 7 to 10, advantageously from 7.5 to 9.5;

[0212] - a polyamide noted C having an average number of carbon atoms per nitrogen atom noted CC of from 9 to 18, advantageously from 10 to 18;

[0213] The aliphatic polyamides noted A, B and C are as defined for the aliphatic polyamide of the outer layer (I) on condition that the average number of carbon atoms per nitrogen atom is respected for each.

[0214] In one embodiment, said composition of the layer (IV) consists mainly of at least one polyamide of aliphatic type or consisting of more than 75% of aliphatic units, said aliphatic polyamide being chosen from:

[0215] - a polyamide noted A having an average number of carbon atoms per nitrogen atom noted CA of from 4 to 8.5, advantageously from 4 to 7;

[0216] - a polyamide noted B and an average number of carbon atoms per nitrogen atom noted CB of from 7 to 10, advantageously from 7.5 to 9.5;

[0217] - a polyamide noted C having an average number of carbon atoms per nitrogen atom noted CC of from 9 to 18, advantageously from 10 to 18.

[0218] In one embodiment, the plasticizer is excluded from the composition of the inner layer (IV) when it is present.

[0219] In one embodiment, the plasticizer is excluded from the composition of the inner layer (III) and the inner layer (IV) when they are present. With regard to the structure as such

[0220] The said structure comprises at least three layers from the outside to the inside:

[0221] (l) / / (ll) / / (lll) or (l) / / (ll) / / (IV)

[0222] In one embodiment, said structure further comprises a layer (V) between layer (I) and layer (II), said layer (V) being made up of a composition comprising predominantly at least one polyamide of aliphatic type or made up of more than 75% of aliphatic units, said aliphatic polyamide being chosen from:

[0223] - a polyamide noted A having an average number of carbon atoms per nitrogen atom noted CA of from 4 to 8.5, advantageously from 4 to 7;

[0224] - a polyamide noted B and an average number of carbon atoms per nitrogen atom noted CB of from 7 to 10, advantageously from 7.5 to 9.5;

[0225] - a polyamide noted C having an average number of carbon atoms per nitrogen atom noted CC of from 9 to 18, advantageously from 10 to 18.

[0226] Said at least one aliphatic type polyamide of said composition of layer (V) is as defined for said aliphatic type polyamide of said composition of layer (IV).

[0227] Said structure can therefore comprise at least four layers when layer (III) and (IV) are present from the outside to the inside:

[0228] (l) / / (H) / / (IV) / / (lll) or when layer (V) is present from the outside to the inside:

[0229] (l) / / (V) / / (ll) / / (lll) or (l) / / (V) / / (ll) / / (IV)

[0230] Said structure may also comprise at least five layers when layer (III) and (IV) are present and when layer (V) is present from the outside to the inside:

[0231] (l) / / (V) / / (ll) / / (IV) / / (lll)

[0232] In a first variant, said structure is made up of three layers from the outside to the inside:

[0233] (l) / / (ll) / / (lll) or (l) / / (ll) / / (IV)

[0234] In a second variant, said structure is made up of four layers from the outside to the inside:

[0235] (l) / / (H) / / (IV) / / (lll) or (l) / / (V) / / (ll) / / (lll) or (l) / / (V) / / (ll) / / (IV)

[0236] In a third variant, said structure is made up of five layers from the outside to the inside: l) / / (V) / / (ll) / / (IV) / / (lll)

[0237] Regardless of the embodiments or variants above, the thickness of the layer (II) in said structure is from 5 to 30%, preferably from 6 to 20% of the sum of the thicknesses of each layer. Advantageously, said structure is chosen from a tank, a pipe and a tube.

[0238] In one embodiment, the proportion of extractables as determined by a test which consists of filling a tubular structure with FAM-B type alcoholic essence and heating the assembly to 60°C for 96 hours, then emptying it by filtering it into a beaker is at most 1 g / m2, in particular 0.8 of insoluble extract.

[0239] Advantageously, the filtrate from the beaker is then left to evaporate at room temperature to weigh this residue, the proportion of which must be less than or equal to approximately 8g / m2, in particular 6g / m2 of internal tube surface.

[0240] FAM B alcoholic gasoline is described in DIN 51604-1:1982, DIN 51604-2:1984 and DIN 51604-3:1984.

[0241] Briefly, FAM A alcoholic gasoline is first prepared with a mixture of 50% Toluene, 30% isooctane, 15% di-isobutylene and 5% ethanol then FAM B is prepared by mixing 84.5% FAM A with 15% methanol and 0.5% water.

[0242] In total, FAM B consists of 42.3% toluene, 25.4% isooctane, 12.7% di-isobutylene, 4.2% ethanol, 15% methanol and 0.5% water.

[0243] According to another aspect, the present invention relates to a composition comprising at least 30%, advantageously 50% by weight relative to the total weight of the composition, of a multilayer structure as defined above, after recycling by grinding and partial or total dissolution of said water-soluble polymer by washing said ground structure with hot water.

[0244] In one embodiment, said composition comprises less than 5% by weight, advantageously 1% by weight of said water-soluble polymer relative to the total weight of said composition after grinding and washing with hot water.

[0245] In one embodiment, the polyamide of said composition comprises functions resulting from oxidation reactions or reactions with automotive fluids.

[0246] The polyamide comprising functions resulting from oxidation reactions or reactions with automotive fluids can come from the outer layer (I) or the inner layer (III) and / or (IV).

[0247] When tubes for transporting or storing fluids are used in motor vehicles, new species resulting from oxidation mechanisms, in particular amide functions and / or methylene alpha to said amide functions, such as imide functions, carboxylic acids, primary amides and alcohols appear in the polyamides constituting said tubes or tanks. Said functions appear due to UV radiation or heat or due to a reaction with a compound with which said object is in contact. For example, gasoline, sunscreen, lubricants, etc.

[0248] These functions can be detected by infrared spectrometry. Thus, the absorption band from 1700 to 1740 cm-1 corresponds to an imide, that from 1680 to 1720 cm-1 to the carbonyl of the carboxylic acid and that from 3580 to 3670 cm-1 corresponds to the alcohol function of the carboxylic acid.

[0249] The absorption band from 3580 to 3670 cm-1 corresponds to the free alcohol function.

[0250] The amide function is characterized on the one hand by a pair of absorption bands from 3100 to 3500 cm-1 and from 15560 to 1640 cm-1 which corresponds to the NH group of the amide and on the other hand by the absorption band from 1650 to 1700 cm-1 which corresponds to the carbonyl group of the amide.

[0251] In one embodiment, said polyamide of said single-layer and / or multi-layer tube having been intended for the transport of automobile fluids, or still used, has functions resulting from oxidation reactions chosen from imide functions, carboxylic acids, alcohols and their mixtures, in a molar ratio relative to the amide functions greater than that of the same polyamide constituting an unused tube having never before transported automobile fluids.

[0252] Advantageously, said molar ratio of the functions resulting from oxidation reactions relative to the secondary amide functions is between 1 / 10000 and 1 / 20.

[0253] Concentrations can be measured by proton NMR in dichloromethane-d2, adding HFIP (hexafluoroisopropanol) to solubilize the polyamide.

[0254] In a first variant, said molar ratio of imide functions is from 1 / 1000 to 1 / 20, in particular from 1 / 500 to 1 / 20, in particular from 1 / 200 to 1 / 50.

[0255] In a second variant, said molar ratio of carboxylic acid functions is from 1 / 5000 to 1 / 20, in particular from 1 / 3000 to 1 / 50, very advantageously from 1 / 500 to 1 / 15.

[0256] In a third variant, said molar ratio of alcohol functions is from 1 / 1000 to 1 / 20 and advantageously from 1 / 1000 to 1 / 25, very advantageously from 1 / 200 to 1 / 50.

[0257] In a fourth variant, said molar ratio of primary amide functions relative to secondary amide functions is from 1 / 2000 to 1 / 20 and advantageously from 1 / 1000 to 1 / 100, very advantageously from 1 / 1000 to 1 / 500.

[0258] In a fifth variant, said molar ratio of nitrile functions relative to secondary amide functions is from 1 / 1000 to 1 / 20 and advantageously from 1 / 500 to 1 / 15, very advantageously from 1 / 100 to 1 / 10.

[0259] In a sixth variant, said molar ratio of methyl functions at the end of the chain relative to the secondary amide functions is from 1 / 5000 to 1 / 50 and advantageously from 1 / 2000 to 1 / 100, very advantageously from 1 / 1000 to 1 / 200.

[0260] It is obvious that depending on the single-layer and / or multi-layer tubes intended for the transport of automobile fluids, or used, and the exposure to which they have been subjected, one or more functions resulting from oxidation reactions may be present. The composition also advantageously comprises stabilizer residues chosen from phenols, quinones, stylbenequinone and phosphite.

[0261] The recycled polyamide advantageously comprises alkyl chain ends with a carbon number (between 1 and 18) higher than that of a virgin PA. Advantageously, the rate of alkyl chain ends is between 1 ppm and 0.5%.

[0262] The used polyamide of said composition is more crystalline than the virgin polyamide.

[0263] The % crystallization can be measured by DSC (or by X-ray).

[0264] Advantageously, the used polyamide has a crystallinity rate of at least 2%, in particular at least 5% higher than that of a virgin polyamide as measured by DSC.

[0265] According to another aspect, the present invention relates to a method for recycling a structure as defined above, characterized in that it comprises a step of grinding then washing with hot water of said structure in order to solubilize and at least partially remove the water-soluble polymer from said structure to obtain the other constituents of said structure.

[0266] The hot water temperature ranges from 70°C to 150°C, especially from 70°C to 120°C.

[0267] Hot water can have a pH between 1 and 12.

[0268] In one embodiment, said method comprises a step of extruding or injecting the other constituents of said structure.

[0269] In one embodiment, said method comprises a compounding step before extrusion or injection.

[0270] This compounding step allows the addition of an impact modifier and / or an additive and / or a plasticizer.

[0271] In another embodiment, said injection or extrusion step makes it possible to obtain another tank, another pipe or another tube.

[0272] EXAMPLES

[0273] The invention will now be described in more detail with the aid of the following examples which are not limiting.

[0274] The following structures were prepared by extrusion:

[0275] Multilayer tubes are produced by coextrusion. A McNeil industrial multilayer extrusion line is used, equipped with 5 extruders, connected to a multilayer extrusion head with spiral mandrels.

[0276] The screws used are single-screw extrusions with screw profiles adapted to polyamides. In addition to the 5 extruders and the multi-layer extrusion head, the extrusion line includes:

[0277] - a die-punch assembly, located at the end of the coextrusion head; the internal diameter of the die and the external diameter of the punch are chosen according to the structure to be produced and the materials it is made of, as well as the dimensions of the tube and the line speed; - a vacuum tank with an adjustable depression level. Water circulates in this tank, generally maintained at 20°C, into which a gauge is immersed to conform the tube to its final dimensions. The diameter of the gauge is adapted to the dimensions of the tube to be produced, typically 8.5 to 10 mm for a tube with an external diameter of 8 mm and a thickness of 1 mm;

[0278] - a succession of cooling tanks in which water is maintained at around 20°C, allowing the tube to be cooled along its route from the head to the drawing bench;

[0279] - a diameter gauge;

[0280] - a draw bench.

[0281] The 5-extruder configuration is used to produce tubes ranging from 2 layers to 5 layers. For structures with fewer than 5 layers, multiple extruders are fed with the same material.

[0282] In the case of structures with 6 layers, an additional extruder is connected and a spiral mandrel is added to the existing head, in order to create the internal layer, in contact with the fluid.

[0283] Before testing, in order to ensure the best tube properties and good extrusion quality, it is checked that the extruded materials have a residual moisture content before extrusion of less than 0.08%. Otherwise, an additional step of drying the material is carried out before testing, generally in a vacuum dryer, for 1 night at 80°C.

[0284] The tubes, which meet the characteristics described in this patent application, were taken after stabilization of the extrusion parameters, the target tube dimensions no longer changing over time. The diameter is controlled by a laser diameter meter installed at the end of the line. The line speed is 20m / min.

[0285] The screw speed of extruders depends on the layer thickness and screw diameter as is known to those skilled in the art.

[0286] Generally speaking, the temperatures of the extruders and tools (head and connector) must be set so as to be sufficiently higher than the melting temperature of the compositions in question, so that they remain in the molten state, thus preventing them from solidifying and blocking the machine.

[0287] The prepared tubular structures (Table 1) were tested on the recyclability parameter (Table 2) according to the following protocol:

[0288] The extruded structures were placed in contact with CE85 gasoline at 60°C for 500 hours, in order to simulate a gasoline line application. After this conditioning, they were ground and washed in water at 85°C for 5 hours, with a mass ratio of ground material in water of 50%.

[0289] The extruded structures were also exposed to hydrogen at 23°C / 0% RH for 168 hours to simulate a storage application. After conditioning, they were ground and washed in water at 85°C for 5 hours, with a mass ratio of ground material to water of 50%.

[0290] After this conditioning, they were ground and washed in water at 85°C for 5 hours, with a mass ratio of ground material in water of 50%.

[0291] The results obtained after exposure to gasoline and hydrogen are identical. A single mass loss value (% by weight) is reported in Table 2.

[0292] The CE85 gasoline and hydrogen permeability measurements are carried out according to the following protocols:

[0293] The gasoline permeability measurement consists of placing CE85 gasoline in a structure, then hermetically sealing the assembly. The latter is placed in an ATEX enclosure regulated at 60°C. Periodic weighings are used to determine the quantity of gasoline vapor diffusing through the structure. A weight loss curve is plotted as a function of time for a 500-hour test, and the permeability coefficient is determined from the slope of the weight loss curve and the surface area of ​​the sample (Protocol 1).

[0294] The hydrogen flow at 23°C and 0% RH is determined according to ISO15105-2 (Protocol 2).

[0295] The qualification of good recyclability was assessed by gravimetry by estimating the mass loss of the shredded material before and after washing. This mass loss was attributed overwhelmingly to the water-soluble polymer.

[0296] [Table 2]

[0297] CEI at 3: counter examples

[0298] Eli at 7: Examples of the invention

[0299] The values ​​in parentheses in Table 1 correspond to the thickness (in pm) of each layer.

[0300] The densities are close to 1.

[0301] EVOH: grade LA107B from Kuraray

[0302] PVOH*: Kuraray mowiflex H15 grade, comprising 97% by weight of vinyl alcohol units PVOH": Kuraray mowiflex C30 grade, comprising 79% by weight of vinyl alcohol units PPVOH: copolymer comprising 90% by weight of vinyl alcohol unit and 10% by weight of propene diol units.

[0303] Tieflex: composition comprising 80% by weight of PA 6 ultramid B40 (BASF), 5% by weight of PA 610 having an Mn of 27,000 g / mol, 5% by weight of a PA 11 having an Mn of 25,000 g / mol and 10% by weight of impact modifier Orevac IM 800 (SK functional polymers)

[0304] PAll a: PA 11 having an Mn of 25,000 g / mol and comprising 10% by weight of Orevac IM 800 impact modifier (SK functional polymers).

[0305] PAll b : PA 11 having an Mn of 25,000 g / mol

[0306] PA12: PA 12 with an Mn of 25,000 g / mol and comprising 10% of Orevac IM 800 impact modifier (SK functional polymers)

[0307] Protocols 1 and 2 defined in Table 2 correspond to the experimental conditions of the permeation tests.

[0308] Protocol 1: CE85 gasoline 60°C for 500 hours

[0309] Protocol 2: Hydrogen 23°C for 168 hoursA mass loss greater than 5% (of the total mass of the tube) means that at least one third (30% by weight) of the barrier layer has dissolved during recycling and therefore that the recycled polyamide will be of better quality.

Claims

CLAIMS 1. Recyclable multi-layer structure for the transport, distribution or storage of fluids, in particular for the distribution or storage of fluids, comprising from the outside to the inside: 1) an outer layer (I) of polyamide, in particular aliphatic, comprising a composition comprising: a) from 41 to 100% by weight of at least one polyamide, in particular aliphatic, having a C / N ratio greater than 7, preferably greater than 8, b) from 0 to 10% of at least one polyamide, in particular aliphatic, different from the previous one, having a C / N ratio less than 10, preferably less than 8, c) from 0 to 30% by weight of at least one impact modifier, d) from 0 to 5% by weight of at least one additive, e) from 0 to 14% by weight of at least one plasticizer, the sum of the constituents a) + b) + c) + d) + e) ​​being equal to 100% by weight, 2) a water-soluble barrier layer (II) at a temperature less than or equal to 150°C, in particular less than or equal to 120°C, 3) an inner layer: (III) polyamide, in particular aliphatic, comprising a composition comprising: a) from 41 to 100% by weight of at least one aliphatic polyamide having a C / N ratio greater than 7, preferably greater than 8, b) from 0 to 10% by weight of at least one polyamide, in particular aliphatic, different from the previous one, having a C / N ratio less than 10, preferably less than 8, c) from 0 to 30% by weight of at least one impact modifier, d) from 0 to 5% by weight of at least one additive, e) from 0 to 14% by weight of at least one plasticizer, the sum of the constituents a) + b) + c) + d) + e) ​​being equal to 100% by weight, and / or (IV) comprising predominantly at least one polyamide of aliphatic type or consisting of more than 75% of aliphatic units, said aliphatic polyamide being chosen from: - a polyamide noted A having an average number of carbon atoms per nitrogen atom noted CA of from 4 to 8.5, advantageously from 4 to 7; - a polyamide noted B and an average number of carbon atoms per nitrogen atom noted CB of from 7 to 10, advantageously from 7.5 to 9.5; - a polyamide noted C having an average number of carbon atoms per nitrogen atom noted CC of from 9 to 18, advantageously from 10 to 18; layer (IV) being adjacent to layer (II) if layer (III) is also present and layer (III) is then the innermost or layer (IV) is the innermost if layer (III) is absent.

2. Recyclable multilayer structure according to claim 1, characterized in that said layer II) water-soluble barrier at a temperature less than or equal to 150°C, in particular less than or equal to 120°C, is made of a water-soluble polymer chosen from copolymers comprising the vinyl alcohol and / or vinyl acetate unit in a content greater than 50% w / w, for example greater than 70% w / w, preferably greater than 80% w / w and a polymer based on milk casein.

3. Recyclable multilayer structure according to one of claims 1 or 2, characterized in that the water-soluble polymer is a copolymer comprising at least (i) a vinyl alcohol unit in a content greater than or equal to 50% by weight, relative to the total weight of said copolymer and (ii) an olefin unit comprising at least one heteroatom in a content less than or equal to 50% by weight, relative to the total weight of said copolymer.

4. Recyclable multilayer structure according to the preceding claim, characterized in that said copolymer comprises said vinyl alcohol unit in a content greater than or equal to 70% by weight, advantageously greater than or equal to 85% by weight, relative to the total weight of said copolymer.

5. Recyclable multilayer structure according to any one of claims 3 and 4, characterized in that said copolymer comprises said olefin unit comprising at least one heteroatom in a content less than or equal to 30% by weight, advantageously less than or equal to 15% by weight, relative to the total weight of said copolymer.

6. Recyclable multilayer structure according to one of claims 1 or 2, characterized in that the water-soluble polymer is a copolymer comprising at least one vinyl alcohol unit in a content greater than or equal to 50% by weight and a vinyl acetate unit in a content less than or equal to 50% by weight, relative to the total weight of said copolymer. Recyclable multilayer structure according to claim 6, characterized in that the water-soluble polymer comprises said vinyl alcohol unit in a content greater than or equal to 70% by weight, for example greater than or equal to 80% by weight, for example greater than or equal to 90% by weight, for example greater than or equal to 95% by weight, relative to the total weight of said copolymer. Recyclable multilayer structure according to claim 6 or 7, characterized in that the water-soluble polymer comprises said vinyl acetate unit in a content less than or equal to 30% by weight, for example less than or equal to 20% by weight, for example less than or equal to 10% by weight, for example less than or equal to 5% by weight, relative to the total weight of said copolymer. Recyclable multilayer structure according to one of claims 1 to 8, characterized in that the melting temperature of the water-soluble polymer is between 160°C and 250°C, in particular between 165°C and 220°C.Recyclable multilayer structure according to one of claims 1 to 9, characterized in that the transformation temperature of the water-soluble polymer is between 180°C and 250°C, in particular between 190°C and 220°C. Recyclable multilayer structure according to one of claims 1 to 10, characterized in that the aqueous solubility of said water-soluble polymer is between 5 and 20%, in particular between 10 and 20% at a temperature between 35°C and 150°C, in particular between 70°C and 150°C. Recyclable multilayer structure according to one of claims 1 to 11, characterized in that a layer (V) is present between layer (I) and layer (II), said layer (V) being made up of a composition comprising predominantly at least one polyamide of aliphatic type or made up of more than 75% of aliphatic units, said aliphatic polyamide being chosen from: - a polyamide noted A having an average number of carbon atoms per nitrogen atom noted CA of from 4 to 8.5, advantageously from 4 to 7; - a polyamide noted B and an average number of carbon atoms per nitrogen atom noted CB of from 7 to 10, advantageously from 7.5 to 9.5; - a polyamide noted C having an average number of carbon atoms per nitrogen atom noted CC of from 9 to 18, advantageously from 10 to 18.

13. Recyclable multi-layer structure according to one of claims 1 to 11, characterized in that it comprises three layers from the outside to the inside: (l) / / (ll) / / (lll) or (l) / / (ll) / / (IV) 14. Recyclable multi-layer structure according to one of claims 12 or 13, characterized in that it comprises four layers from the outside to the inside: (l) / / (V) / / (ll) / / (lll) or (l) / / (V) / / (ll) / / (IV) 15. Recyclable multi-layer structure according to one of claims 12 or 13, characterized in that it comprises five layers from the outside to the inside: (l) / / (V) / / (ll) / / (IV) / / (lll) 16. Recyclable multi-layer structure according to one of claims 1 to 15, characterized in that the thickness of the layer (II) in the structure is from 5 to 30%, preferably from 6 to 20% of the sum of the thicknesses of each layer.

17. Recyclable multilayer structure according to one of claims 1 to 16, characterized in that it is chosen from a tank, a pipe and a tube.

18. Composition comprising at least 30%, advantageously 50% by weight relative to the total weight of the composition, of a multilayer structure as defined in one of claims 1 to 17, after recycling by grinding and partial or total dissolution of the water-soluble polymer by washing said ground structure with hot water.

19. Composition according to claim 18, comprising less than 5% by weight of water-soluble polymer, in particular less than 1% by weight of water-soluble polymer.

20. Method for recycling a structure as defined in one of claims 1 to 17, characterized in that it comprises a step of grinding then washing with hot water of said structure in order to solubilize and at least partially remove the water-soluble polymer from said structure to obtain the other constituents of said structure. Method according to claim 20, characterized in that it comprises a step of extrusion or injection of the other constituents of said structure. Method according to claim 21, characterized in that the injection or extrusion step is preceded by a compounding step. Method according to claim 21 or 22, characterized in that the injection or extrusion step makes it possible to obtain another tank, another pipe or another tube.

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