Recyclable single material object comprising at least two elements

Abstract

The invention relates to a single material object comprising at least two elements: at least one first element consisting of a first composition; the first composition comprises at least 30%, in particular at least 50%, in particular at least 70%, more particularly at least 90% by weight, relative to the total weight of the first element, of a copolyamide having amide units (Ba1) and polyether units (Ba2), at least one second element consisting of a second composition, the second composition comprises at least 30%, in particular at least 50%, in particular at least 70%, more particularly at least 90% by weight, relative to the total weight of the second element, of a copolyamide having amide units (Ba1) and polyether units (Ba2); the copolyamide of the first composition and / or the copolyamide of the second composition has a C / N ratio of units (Ba1) greater than or equal to 8, in particular greater than or equal to 9, notably greater than or equal to 10.

Description

Field of the Invention

[0001] The present patent application relates to recyclable single-material objects comprising at least two (two) elements, to their manufacturing method and their recycling method, to the compositions obtained therefrom, and to their use in the manufacture of objects, in particular single-material objects. Background Art

[0002] Through the circular economy, waste generation, consumption of the planet's resources and environmental impact can be restricted. Currently, particular attention is paid to the production of objects from materials which, after recycling, will have properties sufficient to enable them to be used in high-performance applications and not only in lower-performance applications such as for example for street furniture or roads.

[0003] In the context of sustainable consumption and production patterns, the recyclability of frequently renewed articles such as sports equipment and E&E articles and the quality of the recycled products obtained therefrom are particularly important. However, the performance requirements of these articles are particularly high.

[0004] Objects such as sports equipment and E&E articles must be designed in such a way that they can be recycled into very high-performance materials. It is also important that the products used to manufacture the objects are stable enough to be recycled safely. When thermoplastic polyurethane (TPU) is recycled, the formation of isocyanates can be observed by FTIR. Isocyanates are dangerous CMR compounds.

[0005] To facilitate its recycling, patent EP 3 081 109 B1 proposes a sports shoe in which the upper part and the sole are mainly or even entirely formed of the same thermoplastic base material. However, since the density of the parts of the shoe varies according to their respective functions, difficulties still seem to exist and the recycled products thus obtained have limitations in terms of performance.

[0006] Patent application WO 2020 / 201370A1 proposes a method for recycling such shoes, in which the shoes are ground and then melted. As with the previous one, the document focuses on thermoplastic polyurethane (TPU). The international patent application points out the fact that TPU degrades with the recycling cycles.

[0007] Patent application US 2017 / 0151470 A1 relates to a ball, in particular a football, and to a method for manufacturing and recycling the ball. The ball comprises a bladder, an intermediate layer and an outer layer, and the bladder and the two layers consist of the major component by weight of a material from a first material class selected from polyurethanes, polyvinyl chlorides, polyethylenes, polyamides and polypropylenes.

[0008] The international patent application WO 2021 / 148148 A1 relates to a lined clothing article, which comprises an outer layer, an inner layer and a lining between the two layers.

[0009] Each layer contains a major amount of materials from the same class, which are selected from thermoplastic polymers, especially recycled polyesters or virgin polymers selected from thermoplastic polyurethane (TPU), polyamide (PA), polyethylene terephthalate (PET) or polybutylene terephthalate (PBT). Polyester has the disadvantage of being very sensitive to hydrolysis.

[0010] Therefore, an object of the invention is to propose a single-material object whose composition is studied so that a composition that can be used for applications requiring high performance can be obtained during recycling.

[0011] Now it has been demonstrated that the exclusive combination (excluding additives and fillers) in a single-material object of polyamide fractions (components) and polyamide fractions (components) provides better maintenance of properties during recycling.

[0012] In particular, the impact strength, fatigue strength and mechanical properties (modulus, elongation at break, breaking stress and threshold stress) are maintained. In addition, the density and chemical resistance are maintained.

[0013] Specifically, the presence of PEBA, a flexible compound, in both the first and second components helps to improve the mechanical strength of the entire life of the object, before and after recycling.

[0014] Therefore, according to a first aspect, a subject of the invention is a single-material object comprising at least two components:

[0015] - at least one first component consisting of a first composition, the first composition comprising at least 30% by weight, notably at least 50% by weight, particularly at least 70% by weight, more particularly at least 90% by weight of a copolyamide with amide units (Ba1) and polyether units (Ba2), based on the total weight of the first component,

[0016] - at least one second component consisting of a second composition, the second composition comprising at least 30% by weight, notably at least 50% by weight, particularly at least 70% by weight, more particularly at least 90% by weight of a copolyamide with amide units (Ba1) and polyether units (Ba2), based on the total weight of the second component,

[0017] The first and the second components are capable of adhering to each other at least partially,

[0018] The copolyamide of the first composition and / or the copolyamide of the second composition has a C / N ratio of amide units (Ba1) that is greater than or equal to 8, particularly greater than or equal to 9, notably greater than or equal to 10.

[0019] In one embodiment, the article excludes single or multi-layered structures for transporting, distributing or storing fluids and also excludes catheters.

[0020] Thus, the inventors have unexpectedly found that in a single-material article, an exclusive combination (excluding additives and fillers) of a first fraction (or element) of a copolyamide with specific polyether block amide (PEBA) units (i.e., PEBA having a C / N ratio greater than or equal to 8, particularly greater than or equal to 9, notably greater than or equal to 10) and / or a second fraction (or element) of a copolyamide with specific polyether block amide (PEBA) units (PEBA having a C / N ratio greater than or equal to 8, particularly greater than or equal to 9, notably greater than or equal to 10) allows for better maintenance of properties during recycling. Specifically, the specific copolyamides with polyether block amide (PEBA) units in the two compositions have an optimal compromise and notably provide good aging resistance and thus the lifespan of the article and the recycling process. They can moreover be recycled completely safely.

[0021] Furthermore, the recycled composition has the advantages of having a low density, good elastic recovery, good impact strength, good tensile properties and a stable modulus between -20°C and 30°C.

[0022] The C / N ratio corresponds to the number of carbon atoms per nitrogen atom in unit (Ba1).

[0023] The term "single-material article" should be understood to mean an article consisting mainly of the same material, in this case a polyamide in units (Ba1) having a C / N ratio of at least 6, notably at least 8, particularly at least 9, notably at least 10, where at least one of the copolyamides from the first composition and the copolyamide of the second composition has a C / N ratio of amide units (Ba1) that is greater than or equal to 8, particularly greater than or equal to 9, notably greater than or equal to 10.

[0024] More precisely, the term "mono-material object" shall mean an object comprising at least two elements, at least one element, preferably each element, being composed of a composition respectively comprising at least one polymer matrix, wherein said polymer matrix mainly comprises, i.e. more than 50% by weight relative to its total weight, at least one copolyamide bearing amide units (Ba1) and polyether units (Ba2) as defined according to the invention, having a C / N ratio of units (Ba1) greater than or equal to 8, particularly greater than or equal to 9, notably greater than or equal to 10.

[0025] For the purposes of the present invention, a mono-material object may in particular be an object comprising at least two elements, each element being mono-material, i.e. each element being mainly composed of the same material as defined according to the invention.

[0026] The term "polymer matrix" is intended to denote the part of the composition consisting only of polymers, i.e. non-polymeric fillers and additives are excluded here.

[0027] Preferably, said polymer matrix comprises at least 60% by weight, preferably at least 80% by weight, more preferably at least 90% by weight, advantageously at least 95% by weight, or even 100% by weight of at least one copolyamide bearing amide units (Ba1) and polyether units (Ba2) as defined according to the invention, having a C / N ratio of units (Ba1) greater than or equal to 8, particularly greater than or equal to 9, notably greater than or equal to 10.

[0028] According to one embodiment, a "mono-material object" within the meaning of the present invention is an object comprising at least two elements, at least one element, preferably each element, being composed of a composition mainly comprising, i.e. more than 50% by weight relative to its total weight, at least one copolyamide bearing amide units (Ba1) and polyether units (Ba2) as defined according to the invention, having a C / N ratio of units (Ba1) greater than or equal to 8, particularly greater than or equal to 9, notably greater than or equal to 10.

[0029] Preferably, at least one element, preferably each element, is composed of a composition comprising at least 80% by weight, preferably at least 90% by weight, advantageously at least 95% by weight, or even 100% by weight of at least one copolyamide bearing amide units (Ba1) and polyether units (Ba2) as defined according to the invention, having a C / N ratio of units (Ba1) greater than or equal to 8, particularly greater than or equal to 9, notably greater than or equal to 10.

[0030] According to one embodiment, the single-material object of the present invention is an object comprising at least two elements, each element being composed of a composition comprising less than 20% by weight, preferably less than 10% by weight, such as less than 5% by weight, such as less than 3% by weight, in particular 0% by weight, of short-chain polyamide, i.e. a polyamide having a C / N ratio of strictly less than 8, notably less than or equal to 7, in particular less than or equal to 6, based on its total weight.

[0031] According to one embodiment, the single-material object of the present invention comprises less than 20% by weight, preferably less than 10% by weight, such as less than 5% by weight, such as less than 3% by weight, in particular 0% by weight, of short-chain polyamide, i.e. a polyamide having a C / N ratio of strictly less than 8, notably less than or equal to 7, in particular less than or equal to 6, based on its total weight.

[0032] According to one embodiment, the copolyamide with amide units (Ba1) and polyether units (Ba2) of the first composition and the copolyamide with amide units (Ba1) and polyether units (Ba2) of the second composition mainly comprise the same amide units (Ba1), i.e. more than 50% by weight, or even at least 80% by weight, of the same amide units (Ba1), based on the total weight of said amide units. They may notably comprise 100% by weight of the same amide units (Ba1), based on the total weight of said amide units.

[0033] According to another embodiment, the copolyamide with amide units (Ba1) and polyether units (Ba2) of the first composition and the copolyamide with amide units (Ba1) and polyether units (Ba2) of the second composition mainly comprise the same polyether units (Ba2), i.e. more than 50% by weight, or even at least 80% by weight, of the same polyether units (Ba2), based on the total weight of said polyether units. They may notably comprise 100% by weight of the same polyether units (Ba2), based on the total weight of said polyether units.

[0034] According to another embodiment, the copolyamide with amide units (Ba1) and polyether units (Ba2) of the first composition and the copolyamide with amide units (Ba1) and polyether units (Ba2) of the second composition (i) mainly comprise the same amide units (Ba1), i.e., more than 50% by weight of the same amide units (Ba1), or even at least 80% by weight of the same amide units (Ba1) based on the total weight of the amide units, and (ii) mainly comprise the same polyether units (Ba2), i.e., more than 50% by weight of the same polyether units (Ba2), or even at least 80% by weight of the same polyether units (Ba2) based on the total weight of the polyether units. Notably, they may comprise 100% by weight of the same polyether units (Ba2) based on the total weight of the polyether units. Notably, they may comprise 100% by weight of the same polyether units (Ba2) based on the total weight of the polyether units and 100% by weight of the same amide units (Ba1) based on the total weight of the amide units.

[0035] In a first variant, the single-material object can be, but is not limited to, the following:

[0036] Electronic articles, in particular watches, phone casings, headsets, headphones, speakers, keyboards, mice, phone chargers,

[0037] Clothing articles, in particular jackets, trousers, T-shirts or socks,

[0038] Optical articles, in particular prescription glasses, sunglasses, children's glasses, sports glasses and ski masks, augmented reality / virtual reality goggles,

[0039] Household electrical articles, in particular small household appliances, accessories for household electrical articles (bowls, mixing paddles, food containers), flasks, food containers

[0040] Cosmetic articles, in particular cosmetic packaging such as bottles, perfumes, cosmetic packaging, skin care packaging, display articles, hairbrushes,

[0041] Sports articles, in particular surfboards (and their accessories such as leashes or fins), bicycles, bicycle articles such as saddles or pedals, helmets, ski boots, skis, ski poles, ski bindings and snowboards (excluding metals), golf clubs, any type of racket, in particular tennis rackets, protective equipment such as shin guards, elbow pads, etc., hockey sticks (on grass or ice), roller skates, diving fins,

[0042] Luggage articles, in particular suitcases, travel bags and handbags,

[0043] Stationery articles, in particular pens,

[0044] Toys,

[0045] furniture, and

[0046] motor vehicle parts.

[0047] The statement "the object excludes single - layer or multi - layer structures for transporting, distributing or storing fluids, and also excludes conduits" means that single - layer or multi - layer structures for transporting, distributing or storing fluids are excluded from the object, especially for those with thermal or electric motor equipment, such as airplanes, drones, aircraft, trucks or motor vehicles, and also excludes conduits, which are medical devices in the form of thin flexible tubes.

[0048] In one embodiment of this first variant, the single - material object corresponds to all those described in the list of this first variant, except for at least one of those described in the same list, and excludes single - layer or multi - layer structures for transporting, distributing or storing fluids.

[0049] Needless to say, at least the single - material object corresponds to at least one of those described in the list of this first variant.

[0050] In a second variant, the single - material object can be an electronic product, a textile product, an optical product, a household electrical product, a cosmetic product, a sports product, a stationery product, a luggage product, a toy, furniture, and motor vehicle parts.

[0051] In one embodiment of this second variant, the single - material object corresponds to all those described in the list of this second variant, except for at least one of those described in the same list, and excludes single - layer or multi - layer structures for transporting, distributing or storing fluids.

[0052] Needless to say, at least the single - material object corresponds to at least one of those described in the list of this second variant.

[0053] In a third variant, the single - material object can be an electronic product, a textile product, an optical product, a household electrical product, a cosmetic product, a sports product, a stationery product, a luggage case product, a toy or furniture.

[0054] In one embodiment of this third variant, the single - material object corresponds to all those described in the list of this third variant, except for at least one of those described in the same list, and excludes single - layer or multi - layer structures for transporting, distributing or storing fluids.

[0055] Needless to say, at least the single - material object corresponds to at least one of those described in the list of this third variant.

[0056] In one embodiment of these three variants, the object is excluded from single or multi-layered structures for transporting, distributing or storing fluids and also from conduits.

[0057] The term "fluid" combines any gas in compressed form, liquid form or cryogenic compression and in particular hydrogen, natural gas, LPG, LNG, compressed air, nitrogen, oxygen, and heat transfer fluids, in particular refrigerants selected from the following compounds: hydrocarbons, hydrofluorocarbons, ethers, hydrofluoroethers, CO2, NH3, SO2 and fluoroolefins, in particular R134, R-1234yf or R-1234ze, in particular R-1234yf or R-1234ze, or gases used in motor vehicles, in particular air or liquids used in motor vehicles, in particular water, oil, brake fluid, urea solution, glycol-based coolant, transmission oil coolant (TOC), fuel, in particular diesel, gasoline, more particularly gasoline-alcohol blend or LPG.

[0058] In one embodiment, shoes, balls, motor vehicle seats, travel bags, toothbrushes and jackets are excluded from the single-material objects of the present invention.

[0059] Preferably, the present invention relates to single-material objects obtainable by injection moulding.

[0060] According to one embodiment, the single-material object of the present invention is different from multi-layered structures comprising a fabric layer, a film and optionally a hot-melt adhesive composition between the fabric layer and the film.

[0061] According to one embodiment, the single-material object of the present invention is different from multi-layered structures comprising (i) a fabric layer comprising at least one polymer selected from polyamides and copolymers comprising polyamide blocks and polyether blocks and combinations thereof, and (ii) a film comprising at least one copolymer comprising polyamide blocks and polyether blocks, the polyether blocks comprising polyethylene glycol blocks, the polyethylene glycol blocks accounting for at least 40% by mass relative to the mass of the film, wherein the film is adhered to the fabric layer by a copolyamide.

[0062] According to one embodiment, the single-material object of the invention is different from multi-layered structures comprising (i) a film composed of PA11 / PEG6 (40 / 60 by weight), wherein Mn (PA11) is equal to 1000 g / mol and Mn (PEG) is equal to 1500 g / mol and Tm is equal to 150 °C, and (ii) a film composed of PA6 / 6.12 / 11 / PEG12 (24.5 / 20.9 / 24.5 / 30.1 by weight respectively), wherein Mn (PA) is equal to 2000 g / mol and Mn (PEG) is equal to 600 g / mol and Tm is equal to 100 °C.

[0063] According to one embodiment, the single-material object is different from bandages, gauzes, fabrics, carpets, rugs, upholstery coverings, surface coverings, passenger compartment coverings, sofas, curtains, bedding, mattresses, pillows, clothing, in particular sports clothing or medical clothing.

[0064] According to one embodiment, the single-material object of the present invention is different from soles, in particular from the soles of sports shoes.

[0065] In one embodiment, at least 50% by weight of the polyamide or long-chain copolyamide with amide units (Ba1) in the copolyamide is present in each of the two elements, relative to the total weight of the composition of each element.

[0066] In other words, the total weight of the polyamide with amide units (Ba1) in the first element and the polyamide with amide units (Ba1) in the second element is at least 50% relative to the total weight of the two compositions of each element.

[0067] In another embodiment, the matrix of each of the two elements (excluding fillers and additives) consists of 60% by weight, advantageously 80% by weight, preferably 100% by weight of the polyamide with amide units (Ba1).

[0068] The term "element" means each of the following things that combine to form another thing, the whole, i.e., the single-material object in the present invention.

[0069] In particular, an element means a component, a constituent, a fragment, a part (a component), a sheet or a unit that constitutes a single-material object.

[0070] The statement "the first and second elements may be at least partially adhered to each other" means that the first and second elements may or may not be adhered to each other.

[0071] In one embodiment, the first and second elements are not adhered to each other.

[0072] In another embodiment, the first and second elements are at least partially, in particular completely, adhered to each other.

[0073] The term "adhered" means that the first and second elements are placed against each other or applied against each other at least partially and in particular by bonding, clamping, overmolding, thermoforming, screwing, stitching, welding or riveting.

[0074] Needless to say, the first and second compositions containing the copolyamide with amide units (Ba1) and polyether units (Ba2) may also contain an impact modifier and / or a plasticizer and / or a filler and / or an additive.

[0075] Needless to say, the third composition described below may comprise long-chain homopolyamides and long-chain copolyamides or copolyamides with amide units (Ba1) and polyether units (Ba2), or a mixture of both, and may also comprise an impact modifier and / or a plasticizer and / or a filler and / or an additive.

[0076] Copolyamide with amide units (Ba1) and polyether units (Ba2) (PEBA) for the composition of the first, second, and third elements

[0077] Polyether block amide (PEBA) is a copolymer containing amide units (Ba1) and polyether units (Ba2), and the amide units (Ba1) correspond to aliphatic repeating units, and the aliphatic repeating units are selected from units obtained from at least one amino acid or units obtained from at least one lactam, or units obtained from the polycondensation of the following X.Y:

[0078] - At least one diamine, which is preferably selected from linear or branched aliphatic diamines, or a mixture thereof, and

[0079] - At least one dicarboxylic acid, which is preferably selected from:

[0080] - Linear or branched aliphatic dicarboxylic acids or a mixture thereof,

[0081] The diamine and the dicarboxylic acid contain 4 to 36 carbon atoms, advantageously 6 to 18 carbon atoms;

[0082] The polyether unit (Ba2) is notably obtained from at least one polyalkylene ether polyol, notably a polyalkylene ether diol.

[0083] PEBA is notably produced by the polycondensation of a polyamide block with reactive ends and a polyether block with reactive ends. For example, in particular:

[0084] 1) A polyamide block with diamine chain ends and a polyoxyalkylene block with dicarboxylic acid chain ends.

[0085] 2) A polyamide block with dicarboxylic acid chain ends and a polyoxyalkylene block with diamine chain ends, obtained by the cyanoethylation and hydrogenation of an aliphatic α,ω-dihydroxylated polyoxyalkylene block called a polyalkylene ether diol (polyether diol).

[0086] 3) A polyamide block with dicarboxylic acid chain ends and a polyether diol, and the product obtained in this particular case is a polyether ester amide. The copolymer of the present invention is advantageously of this type.

[0087] The polyamide block with dicarboxylic acid chain ends, for example, is derived from the condensation of a polyamide precursor in the presence of a chain-limiting dicarboxylic acid.

[0088] Polyamide blocks with diamine chain ends, for example, are derived from the condensation of polyamide precursors in the presence of chain-limiting diamines.

[0089] Polymers having polyamide blocks and polyether blocks may also contain randomly distributed units. These polymers can be prepared by the simultaneous reaction of precursors of polyethers and polyamide blocks.

[0090] For example, a polyether diol, a polyamide precursor, and a chain-limiting diacid can be reacted. The resulting polymer essentially has polyamide blocks and polyether blocks of very variable lengths, but also various reagents that react randomly, which are randomly (statistically) distributed along the polymer chain.

[0091] A polyether diamine, a polyamide precursor, and a chain-limiting diacid can also be reacted. The resulting polymer essentially has polyamide blocks and polyether blocks of very variable lengths, but also various reagents that react randomly, which are randomly (statistically) distributed along the polymer chain.

[0092] Amide unit (Ba1):

[0093] The amide unit (Ba1) corresponds to the aliphatic repeating unit defined above.

[0094] The amide unit (Ba1) of the copolyamide of the composition of the first, second, and third elements has a C / N ratio greater than or equal to 6, notably greater than or equal to 8, especially greater than or equal to 9, notably greater than or equal to 10.

[0095] Advantageously, the amide unit (Ba1) is selected from polyamide 11, polyamide 12, polyamide 610, polyamide 612, polyamide 1010, polyamide 910, polyamide 613, polyamide 514, polyamide 109, polyamide 1011, polyamide 516, polyamide 615, polyamide 913, polyamide 129, polyamide 1012, especially polyamide 11.

[0096] More advantageously, the amide unit (Ba1) is selected from polyamide 11 and polyamide 12, especially polyamide 11.

[0097] According to one embodiment, the amide units (Ba1) of the copolyamide with amide units (Ba1) and polyether units (Ba2) present in the first element of the single-material object of the present invention and / or the amide units (Ba1) of the copolyamide with amide units (Ba1) and polyether units (Ba2) present in the second element of the single-material object of the present invention contain less than 20% by weight, preferably less than 10% by weight, advantageously less than 5% by weight, and in particular less than 2% by weight of units having a C / N ratio of less than 8. In one embodiment, the units (Ba1) do not contain (i.e., contain less than 0.1% by weight, preferably 0% by weight) amide units with a C / N ratio of less than 8.

[0098] Polyether units (Ba2):

[0099] The polyether units notably derive from at least one polyalkylene ether polyol. In other words, the polyether units are formed by at least one polyalkylene ether polyol. In this embodiment, the term "at least one polyalkylene ether polyol" means that the polyether units consist only of alcohol chain ends and thus cannot be compounds of the polyether diamine triblock type.

[0100] Therefore, the composition of the invention does not contain polyether diamine triblocks.

[0101] According to one embodiment, the copolyamide with amide units (Ba1) and polyether units (Ba2) of the first composition and / or the copolyamide with amide units (Ba1) and polyether units (Ba2) of the second composition mainly contain, i.e., at least 50% by weight based on the total weight of the polyether units, polyether units (Ba2) with a C / O ratio greater than 3, such as greater than 3.5.

[0102] The copolyamide with amide units (Ba1) and polyether units (Ba2) of the first composition and / or the copolyamide with amide units (Ba1) and polyether units (Ba2) of the second composition may notably contain at least 80% by weight, or even 100% by weight based on the total weight of the polyether units, polyether units (Ba2) with a C / O ratio greater than 3, such as greater than 3.5.

[0103] Advantageously, the polyether units (Ba2) are selected from polyethylene glycol (PEG), polypropylene glycol (PPG), polytrimethylene glycol (PO3G), polytetramethylene glycol (PTMG), their mixtures or copolymers, especially PTMG.

[0104] According to one embodiment, the polyether units (Ba2) of the copolyamide with amide units (Ba1) and polyether units (Ba2) present in the first element of the single-material object of the present invention and / or the polyether units (Ba2) of the copolyamide with amide units (Ba1) and polyether units (Ba2) present in the second element of the single-material object of the present invention contain less than 20% by weight, preferably less than 10% by weight, advantageously less than 5% by weight, notably less than 2% by weight of the copolyamide with amide units (Ba1) and short-chain polyether units (Ba2), i.e., the polyether units have a C / O ratio less than or equal to 3, notably less than or equal to 2.

[0105] For the purposes of the invention, the C / O ratio corresponds to the unit ratio between the number of carbon atoms and the number of oxygen atoms in the polyether unit.

[0106] According to one embodiment, the polyether units (Ba2) of the copolyamide with amide units (Ba1) and polyether units (Ba2) present in the first element of the single-material object of the present invention and / or the polyether units (Ba2) of the copolyamide with amide units (Ba1) and polyether units (Ba2) present in the second element of the single-material object of the present invention contain less than 20% by weight, preferably less than 10% by weight, advantageously less than 5% by weight, notably less than 2% by weight of polyethylene glycol (PEG), polypropylene glycol (PPG) and / or polytrimethylene glycol (PO3G), especially polyethylene glycol (PEG).

[0107] According to one embodiment, the single-material object of the present invention contains less than 20% by weight, preferably less than 10% by weight, for example less than 5% by weight, for example less than 3% by weight, especially 0% by weight, based on its total weight, of the copolyamide with amide units (Ba1) and short-chain polyether units (Ba2), i.e., the polyether units have a C / O ratio less than or equal to 3, especially less than or equal to 2.

[0108] In one embodiment, the (Ba2) units do not contain (i.e., contain less than 0.1% by weight, preferably 0% by weight) polyethylene glycol (PEG), polypropylene glycol (PPG) and / or polytrimethylene glycol (PO3G), especially polyethylene glycol (PEG).

[0109] Advantageously, a low water absorption rate and thus a lower density of the single-material object of the present invention are observed during use when the latter contains little or even no copolyamide with amide units (Ba1) and short-chain polyether units (Ba2) (i.e., the polyether units have a C / O ratio less than or equal to 3, notably less than or equal to 2).

[0110] The number-average molecular weight (Mn) of the polyether block is advantageously from 200 to 4000 g / mol, preferably from 250 to 2500 g / mol, in particular from 300 to 1100 g / mol.

[0111] In one embodiment, the difference in number-average molar mass between the polyether segments of the copolyamide having amide units (Ba1) and polyether units (Ba2) present in the first element of the monomaterial object of the invention on the one hand and the polyether segments of the copolyamide having amide units (Ba1) and polyether units (Ba2) present in the second element of the monomaterial object of the invention on the other hand is less than 1000 g / mol, preferably 500 g / mol, advantageously 300 g / mol.

[0112] In one embodiment, the number-average molar mass of the polyether segments of the copolyamide having amide units (Ba1) and polyether units (Ba2) present in the first element of the monomaterial object of the invention is the same as the number-average molar mass of the polyether segments of the copolyamide having amide units (Ba1) and polyether units (Ba2) present in the second element of the monomaterial object of the invention.

[0113] The PEBA can be prepared by the following method, wherein:

[0114] - In a first step, a polyamide block (Ba1) is prepared by polycondensation in the presence of a chain limiter selected from dicarboxylic acids

[0115] lactam, or

[0116] amino acid, or

[0117] diamine and dicarboxylic acid; and, where appropriate, comonomers selected from lactams and α,ω-aminocarboxylic acids;

[0118] And then

[0119] - In a second step, the polyamide block (Ba1) obtained is reacted with a polyether block (Ba2) in the presence of a catalyst.

[0120] The two-step general method for preparing the copolymers of the invention is known and is described, for example, in French patent FR 2 846332 and European patent EP 1 482 011.

[0121] The reaction for forming block (Ba1) is generally carried out at 180 °C to 300 °C, preferably 200 °C to 290 °C, and the pressure in the reactor is brought to between 5 bar and 30 bar and maintained for about 2 hours to 3 hours. The pressure is slowly reduced while returning the reactor to atmospheric pressure and then, for example, the excess water is evaporated off within 1 or 2 hours.

[0122] Once a polyamide with carboxylic acid end groups has been prepared, a polyether and a catalyst are then added. The polyether can be added in one or more portions, and so can the catalyst. According to an advantageous form, the polyether is added first; the reaction of the OH end groups of the polyether and the COOH end groups of the polyamide begins with the formation of ester bonds and the elimination of water. As much water as possible is removed from the medium by distillation, and then the catalyst is introduced to complete the linking of the polyamide block and the polyether block. This second step is carried out with stirring, preferably under a vacuum of at least 15 mmHg (2000 Pa), at a temperature such that the reagents and the copolymer obtained are in a molten form. For example, this temperature can be from 100 °C to 400 °C, and more commonly from 200 °C to 300 °C. Monitoring is carried out by measuring the torque exerted on the stirrer by the molten polymer or by measuring the electrical power consumed by the stirrer. The end of the reaction is determined by the target torque or power value.

[0123] During the synthesis, one or more molecules used as antioxidants, such as Irganox ® 1010 or Irganox ® 245, can also be added at the moment considered to be the most appropriate.

[0124] A method for preparing PEBA can also be considered, which involves adding all the monomers at the beginning, i.e., in a single step, to achieve the following polycondensation:

[0125] lactam, or

[0126] amino acid, or

[0127] diamine and dicarboxylic acid; and, if appropriate, other polyamide comonomers;

[0128] - in the presence of a chain limiter selected from dicarboxylic acids;

[0129] - in the presence of a (Ba2)(polyether) block;

[0130] - in the presence of a catalyst for between the flexible (Ba2) block and the (Ba1) block.

[0131] Advantageously, the dicarboxylic acid is used as a chain limiter and is introduced in a stoichiometric excess relative to the diamine.

[0132] Advantageously, derivatives of metals selected from titanium, zirconium, and hafnium, or strong acids such as phosphoric acid, hypophosphorous acid, or boric acid are used as catalysts.

[0133] The polycondensation can be carried out at a temperature of 240 to 280 °C.

[0134] Generally, known copolymers with ether and amide units consist of copolymers of semi-crystalline linear, aliphatic polyamide blocks (such as Pebax from Arkema).

[0135] In one embodiment, the copolyamide with amide units (Ba1) and polyether units (Ba2) has a density greater than or equal to 1, in particular greater than or equal to 1.01, notably greater than or equal to 1.02, as measured according to ISO 1183-3:1999.

[0136] In one embodiment, polyetheramines are excluded from the polyether units (Ba2).

[0137] In one embodiment, the copolyamide with amide units (Ba1) and polyether units (Ba2) present in the first composition of the first element constituting the single-material object of the present invention and / or the copolyamide with amide units (Ba1) and polyether units (Ba2) present in the second composition of the second element constituting the single-material object of the present invention has a Shore D hardness less than or equal to 50D, notably less than or equal to 45D.

[0138] Long-chain homopolyamides and copolyamides of the composition of the third element.

[0139] The nomenclature used to define polyamides is described in the standard ISO 1874-1:2011 "Plastics - Polyamide (PA) molding and extrusion materials - Part 1: Designation", particularly on page 3 (Tables 1 and 2), and is well-known to those skilled in the art.

[0140] The long-chain homopolyamides and copolyamides are polyamides having a C / N ratio (i.e., the average number of carbon atoms per nitrogen atom) greater than or equal to 6, in particular greater than or equal to 8, more particularly greater than or equal to 9, notably greater than or equal to 10.

[0141] In a first variant of the present invention, the repeating unit is a unit obtained by polycondensation of at least one C4-C 36 amino acid (or aminocarboxylic acid).

[0142] Advantageously, the aminocarboxylic acid contains 9 to 12 carbon atoms. Thus, it can be selected from 9-aminononanoic acid (denoted as 9), 10-aminodecanoic acid (denoted as 10), 11-aminoundecanoic acid (denoted as 11), and 12-aminododecanoic acid (denoted as 12); advantageously, the aminocarboxylic acid is 11-aminoundecanoic acid.

[0143] In a second variant of the invention, the repeating unit is a unit obtained by polycondensation of at least one C4-C36 lactam.

[0144] Advantageously, the lactam contains 9 to 12 carbon atoms. Thus, it may be caprolactam (designated as 6), decanolactam (designated as 10), undecanolactam (designated as 11), and laurolactam or lauryl lactam (designated as 12); advantageously, the lactam is lauryl lactam.

[0145] However, it is perfectly conceivable to use a mixture of two or more amino acids, a mixture of two or more lactams, and also a mixture of one, two or more amino acids with one, two or more lactams.

[0146] More particularly preferably, the repeating unit is obtained from a single amino acid or a single lactam.

[0147] Repeating unit XY

[0148] The repeating unit XY is obtained by polycondensation of a unit of at least one diamine and at least one dicarboxylic acid,

[0149] The diamine is selected from linear or branched aliphatic diamines, cycloaliphatic diamines, and semi-aromatic aliphatic diamines or mixtures thereof, and

[0150] At least one dicarboxylic acid, the diacid being selected from:

[0151] Aliphatic diacids, cycloaliphatic diacids, and aromatic diacids or mixtures thereof,

[0152] The molar ratio of diamine to dicarboxylic acid is preferably stoichiometric.

[0153] The diamine contains 4 to 36 carbon atoms, advantageously 6 to 18 carbon atoms.

[0154] According to one embodiment, the diamine contains 6 to 12 carbon atoms.

[0155] In the case where the diamine used to prepare the repeating unit XY is an aliphatic diamine having a linear backbone, the linear backbone may, if appropriate, include one or more methyl and / or ethyl substituents; in the latter configuration, it is referred to as a "branched aliphatic diamine". In the case where the backbone does not include any substituents, the aliphatic diamine is referred to as a "linear aliphatic diamine".

[0156] Regardless of whether it includes methyl and / or ethyl substituents on the backbone, the aliphatic diamine used to obtain the repeating unit XY contains 4 to 36 carbon atoms, advantageously 6 to 18 carbon atoms, notably 9 to 18 carbon atoms.

[0157] When the diamine is a straight-chain aliphatic diamine, it corresponds to the formula H2N-(CH2)x-NH2 and can be selected, for example, from butanediamine, pentanediamine, hexanediamine, heptanediamine, octanediamine, nonanediamine, decanediamine, undecanediamine, dodecanediamine, tridecanediamine, tetradecanediamine, hexadecanediamine, octadecanediamine, and octadecenediamine. The straight-chain aliphatic diamines just mentioned can all be bio-based within the meaning of standard ASTM D6866.

[0158] When such a diamine is a branched-chain aliphatic diamine, it can in particular be 2-methylpentanediamine, 2-methyl-1,8-octanediamine, or (2,2,4- or 2,4,4-)trimethylhexanediamine.

[0159] The cycloaliphatic diamines can be selected, for example, from bis(3,5-dialkyl-4-aminocyclohexyl)methane, bis(3,5-dialkyl-4-aminocyclohexyl)ethane, bis(3,5-dialkyl-4-aminocyclohexyl)propane, bis(3,5-dialkyl-4-aminocyclohexyl)butane, bis(3,5-dialkyl-4-aminocyclohexyl)methane, or 3'-dimethyl-4,4'-diaminodicyclohexylmethane, commonly known as "BMACM" or "MACM" (and denoted hereinafter as B), p-bis(aminocyclohexyl)methane, commonly known as "PACM" (and denoted hereinafter as P), isopropylidene di(cyclohexylamine), commonly known as "PACP", isophorone diamine (denoted hereinafter as IPD), and 2,6-bis(aminomethyl)norbornane, commonly known as "BAMN", or bis(aminomethyl)norbornane, commonly known as "BAC", or bis(aminomethyl)cyclohexane, commonly known as "BAC".

[0160] A non-exhaustive list of these cycloaliphatic diamines is given in the publication "Cycloaliphatic Amines" (Encyclopedia of Chemical Technology, Kirk-Othmer, 4th edition (1992), pages 386-405).

[0161] When the diamine is a semi-aromatic aliphatic diamine, it is selected, for example, from 1,3-benzenedimethanamine and 1,4-benzenedimethanamine.

[0162] The dicarboxylic acid contains 4 to 36 carbon atoms, advantageously 6 to 18 carbon atoms, and notably 6 to 12 carbon atoms.

[0163] When the dicarboxylic acid is aliphatic, it can be selected from straight-chain or branched-chain aliphatic dicarboxylic acids.

[0164] When the dicarboxylic acid is aliphatic and straight-chain, it may be selected from succinic acid (4), glutaric acid (5), adipic acid (6), pimelic acid (7), suberic acid (8), azelaic acid (9), sebacic acid (10), undecanedioic acid (11), dodecanedioic acid (12), tridecanedioic acid (13), tetradecanedioic acid (14), hexadecanedioic acid (16), octadecanedioic acid (18), octadecenedioic acid (18), eicosanedioic acid (20), docosanedioic acid (22), and fatty acid dimers containing 36 carbons.

[0165] The above-mentioned fatty acid dimers are dimeric fatty acids obtained by oligomerization or polymerization of unsaturated monocarboxylic acids having long hydrocarbon chains (such as linoleic acid and oleic acid), as notably described in EP 0 471 566.

[0166] When the dicarboxylic acid is aromatic, it may be selected from terephthalic acid (denoted as T), isophthalic acid (denoted as I), and naphthalenedicarboxylic acid (denoted as N).

[0167] In one embodiment, the composition of the first element consists of a single homopolyamide.

[0168] In another embodiment, the homopolyamide of the composition of the third element is an aliphatic semi-crystalline homopolyamide.

[0169] For the purposes of the invention, the term "semi-crystalline homopolyamide" refers to a material that is generally solid at room temperature and softens during temperature increase, particularly after passing through its glass transition temperature (Tg), and can melt sharply when passing through its "melting temperature" (Tm), and becomes solid again when the temperature is lowered below its crystallization temperature.

[0170] For the purposes of the invention, the semi-crystalline homopolyamide has a melting temperature (Tm) according to standard ISO 11357-3:2013 (by DSC) and a crystallization enthalpy greater than 25 J / g, preferably greater than 40 J / g, according to standard ISO 11357-3 (2013) during the cooling step at a rate of 20 K / min (by DSC).

[0171] Tg, Tc, and Tm are determined by differential scanning calorimetry (DSC) according to standards 11357-2:2013 and 11357-3:2013, respectively.

[0172] The number-average molecular weight Mn of the semi-crystalline homopolyamide is preferably in the range extending from 10,000 to 85,000, notably from 10,000 to 60,000, preferably from 10,000 to 50,000, and even more preferably from 12,000 to 50,000. These Mn values can correspond to an intrinsic viscosity greater than or equal to 0.8 as determined in m-cresol according to standard ISO 307:2007 but with a change in solvent (using m-cresol instead of sulfuric acid and at a temperature of 20 °C).

[0173] The intrinsic viscosity of at least one homopolyamide or at least one copolyamide is from 0.8 to 2, preferably from 1 to 1.8, and advantageously from 1.2 to 1.6.

[0174] The use of a homopolyamide and / or copolyamide having a specific intrinsic viscosity, namely from 0.8 to 2, preferably from 1 to 1.8, more preferably from 1.2 to 1.6, advantageously allows the obtaining of a monomaterial object according to the invention having good mechanical properties.

[0175] It has also been advantageously found that the use of a homopolyamide and / or copolyamide having a specific intrinsic viscosity (i.e., from 0.8 to 2, preferably from 1 to 1.8, more preferably from 1.2 to 1.6) in at least two constituent elements of the monomaterial object according to the invention (wherein said elements are adjacent within the monomaterial of the invention) also allows the improvement or even maximization of the adhesion between these elements. This allows a reduction in the amount of adhesive required for the assembly of these elements, or even the elimination of the presence of the adhesive, which further increases the recyclability of the monomaterial.

[0176] Regarding the monomaterial object

[0177] It consists of at least two elements: the at least one first element defined herein as (E1) and the at least one second element defined herein as (E2).

[0178] In a first variant, it consists of two said elements: E1 / E2.

[0179] Element E1 can adhere at least partially to element E2; in particular, E1 and E2 adhere at least partially and in particular E1 and E2 adhere completely, in particular by means of an adhesive.

[0180] Then the monomaterial object is selected from the above-mentioned ones.

[0181] In a second variant, it consists of more than two elements: E1 / (E1)n / E2 / (E2)m, where n and m are from 0 to 5, and when n = 0, then m > 0, and when m = 0, then n > 0.

[0182] Needless to say, when two elements E1 or E2 are side by side, they can adhere at least partially to each other.

[0183] In one embodiment, the copolyamide of elements E1 and E2 comprises the same monomers, notably at least 5% by weight, advantageously at least 10% by weight, preferably at least 20% by weight of the same monomers, such as 11 - aminoundecanoic acid, relative to the sum of the constituents of the copolyamide.

[0184] In one embodiment, the polyamide units of the copolyamide of elements E1 and E2 comprise monomers having the same C / N ratio, notably at least 5% by mass, advantageously 10% by mass, preferably 30% by mass of monomers having the same C / N ratio relative to the sum of the constituents of the homopolyamide or copolyamide.

[0185] In another embodiment, the copolyamide of elements E1 and E2 comprises the same polyether units (Ba2), in particular polytetramethylene glycol (PTMG).

[0186] In yet another embodiment, the copolyamide of elements E1 and E2 comprises the same monomers, such as 11 - aminoundecanoic acid, notably at least 5% by weight, advantageously at least 10% by weight, preferably at least 20% by weight of the same monomers relative to the sum of the constituents of the copolyamide, and the copolyamide of elements E1 and E2 comprises the same polyether units (Ba2), in particular polytetramethylene glycol (PTMG).

[0187] In another embodiment, the polyamide units of the copolyamide of elements E1 and E2 comprise monomers having the same C / N ratio, notably at least 5% by mass, advantageously 10% by mass, preferably 30% by mass of monomers having the same C / N ratio relative to the sum of the homopolyamide or copolyamide, and the copolyamide of elements E1 and E2 comprises the same polyether units (Ba2), in particular polytetramethylene glycol (PTMG).

[0188] In one embodiment, the first and second compositions comprise the same polyamide units, in particular PA11.

[0189] In another embodiment, the first and second elements are selected from the following constituents: fabrics, films or textured films, foams, injection - molded parts, extrusion parts, 3D - printed parts, adhesives, non - woven fabrics, meshes and consolidated thermoplastic composite parts, preferably selected from fabrics, foams, injection - molded parts, 3D - printed parts, adhesives, non - woven fabrics, meshes and consolidated thermoplastic composite parts.

[0190] According to one embodiment, the first and / or second element is different from a film.

[0191] According to one embodiment, the first and / or second element is different from an extrusion part.

[0192] Advantageously, the single-material object comprises at least two or more of the defined and different constituent elements.

[0193] Advantageously, the single-material object comprises at least three constituent elements, in particular different constituent elements as defined above.

[0194] In another embodiment, the first and second elements are adhered to each other by bonding with the aid of a non-polyamide adhesive, the content of which ranges from 0.01% by weight to 10% by weight, in particular from 0.1% by weight to 4% by weight, relative to the total mass of the object.

[0195] According to another embodiment, the single-material object of the present invention comprises less than 0.1% by weight, preferably less than 0.01% by weight, and more particularly 0% by weight of non-polyamide adhesive.

[0196] In particular, they may comprise less than 0.1% by weight, preferably less than 0.01% by weight, and more particularly 0% by weight of the encapsulated adhesion promoter (P), the adhesion promoter comprising at least one organic molecule which comprises at least two isocyanate functional groups closed by encapsulating the organic molecule, notably as defined in US 2011 / 0111208.

[0197] According to one embodiment, the single-material object of the present invention comprises less than 0.1% by weight, preferably less than 0.01% by weight, and more particularly 0% by weight of the dispersion of polyisocyanate in water and / or organic solvent, in particular as defined in US 2011 / 0111208.

[0198] Preferably, when the single-material object of the present invention comprises an adhesive, this is different from the dispersion in a solvent, in particular in water and / or in an organic solvent. In particular, when the single-material object of the invention comprises an adhesive, this is different from the dispersion in solvent MEK (methyl ethyl ketone) and / or C1-C5 alkyl acetate, in particular ethyl acetate.

[0199] In particular, the single-material object of the invention comprises less than 0.1% by weight, preferably less than 0.01% by weight, and more particularly 0% by weight of the adhesion promoter which contains a solution of polyurethane modified in a MEK + ethyl acetate solvent (dry extract - 30 min at 150 °C = 46.9% by mass of polyurethane).

[0200] Specifically, due to environmental reasons, such non-polyamide adhesives should be avoided because they are somewhat toxic. Such non-polyamide adhesives also have a negative impact on the recyclability of the single-material object according to the present invention because they cannot be easily separated and / or because they are crosslinked and thus cannot be recycled.

[0201] In particular, as shown above, when thermoplastic polyurethane (TPU) is recycled, the formation of isocyanates can be observed by FTIR. However, isocyanates are compounds harmful to health and the environment (CMR classification), and in the context of the present invention, their formation is sought to be avoided.

[0202] In one embodiment, elements 1 and 2 are adhered to each other by a polyamide adhesive.

[0203] Notably, it may comprise at least one copolyamide hot melt adhesive composition, such as those described in WO 2022 / 090665.

[0204] According to another embodiment, elements 1 and 2 are directly adhered to each other, i.e., without an adhesive.

[0205] In a third variant, it may consist of more than two elements: said at least one first element defined herein as (E1) and said at least one second element defined herein as (E2) and said third element defined herein as E3.

[0206] In one embodiment, it consists of three elements: E1 / E2 / E3 or E1 / E3 / E2 or E3 / E1 / E2.

[0207] Element E1 may be at least partially adhered to element E2; in particular, E1 and E2 are at least partially adhered, especially E1 and E2 are fully adhered, especially by an adhesive.

[0208] Element E2 may be at least partially adhered to element E3; in particular, E2 and E3 are at least partially adhered, especially E2 and E3 are fully adhered, especially by an adhesive.

[0209] If there is at least one other element E1 and / or E2 and / or E3 in the monomaterial object, it is not outside the scope of the invention.

[0210] In a first variant, the first element is of non-recycled origin.

[0211] In a second variant, the second element is of non-recycled origin.

[0212] In a third variant, the third element (if present) is of non-recycled origin.

[0213] In a fourth variant, the first element and the second element are of non-recycled origin.

[0214] In a fifth variant, the first element and the third element (when they are present) are of non-recycled origin.

[0215] In a sixth variant, the second and third elements (when they are present) are of non-recycled origin.

[0216] In a seventh variant, the first, second and third elements (when present) are of non-recycled origin.

[0217] In an eighth variant, the first element is at least partially of recycled origin.

[0218] In a ninth variant, the second element is at least partially of recycled origin.

[0219] In a tenth variant, the third element (if present) is at least partially of recycled origin.

[0220] In an eleventh variant, the first and second elements are at least partially of recycled origin.

[0221] In a twelfth variant, the first and third elements (when they are present) are at least partially of recycled origin.

[0222] In a thirteenth variant, the second and third elements (when they are present) are at least partially of recycled origin.

[0223] In a fourteenth variant, the first, second and third elements (when they are present) are at least partially of recycled origin.

[0224] The term "at least partially recycled" means that there is at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% of a recycled composition in the element, and the recycled composition itself contains at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% of a copolyamide with amide units (Ba1) and polyether units (Ba2) of recycled origin.

[0225] In one embodiment, when the single material consists of three or more elements, the composition of the third element comprises at least one long-chain homopolyamide or at least one long-chain copolyamide.

[0226] In another embodiment, when the single material consists of three or more elements, the composition of the third element (E3) comprises at least one copolyamide with amide units (Ba1) and polyether units (Ba2).

[0227] In yet another embodiment, when the single material consists of three or more elements, the composition of the third element comprises a blend of at least one long-chain homopolyamide or at least one long-chain copolyamide and at least one copolyamide with amide units (Ba1) and polyether units (Ba2).

[0228] In another embodiment, the composition of the first element (E1) comprises a single copolyamide having amide units (Ba1) and polyether units (Ba2).

[0229] In another embodiment, the composition of the second element (E2) comprises a single copolyamide having amide units (Ba1) and polyether units (Ba2).

[0230] In another embodiment, the composition of the third element (E3), if present, comprises a single long-chain homopolyamide or at least one long-chain copolyamide.

[0231] In another embodiment, the composition of the third element (E3), if present, comprises a single copolyamide having amide units (Ba1) and polyether units (Ba2).

[0232] In another embodiment, the composition of the first element (E1) comprises a single copolyamide having amide units (Ba1) and polyether units (Ba2), and the composition of the second element (E2) comprises a single copolyamide having amide units (Ba1) and polyether units (Ba2).

[0233] In another embodiment, the composition of the first element (E1) comprises a single copolyamide having amide units (Ba1) and polyether units (Ba2), the composition of the second element (E2) comprises a single copolyamide having amide units (Ba1) and polyether units (Ba2), and the composition of the third element (E3), if present, comprises a single long-chain homopolyamide or at least one long-chain copolyamide.

[0234] In another embodiment, the composition of the first element (E1) comprises a single copolyamide having amide units (Ba1) and polyether units (Ba2), the composition of the second element (E2) comprises a single copolyamide having amide units (Ba1) and polyether units (Ba2), and the composition of the third element (E3), if present, comprises a single copolyamide having amide units (Ba1) and polyether units (Ba2).

[0235] According to another aspect, the present invention relates to a method for manufacturing a single-material object as defined above, which comprises steps including:

[0236] - providing a first element consisting of a first composition, the first composition comprising at least 30% by weight, notably at least 50% by weight, particularly at least 70% by weight, more particularly at least 90% by weight of at least one copolyamide having amide units (Ba1) and polyether units (Ba2) as defined above, based on the total weight of the first element

[0237] - providing a second element composed of a second composition, the second composition comprising at least 30% by weight, notably at least 50% by weight, particularly at least 70% by weight, more particularly at least 90% by weight of at least one copolyamide with amide units (Ba1) and polyether units (Ba2) as defined above, relative to the total weight of the second element

[0238] assembling the elements of the object by means of an adhesive, where appropriate, to form a finished or semi-finished object.

[0239] In one embodiment, the method defined above includes an additional step of providing a third element composed of a third composition before assembly, the third composition comprising at least 30% by weight, in particular at least 50% by weight, in particular at least 70% by weight, more particularly at least 90% by weight of at least one long-chain homopolyamide or at least one long-chain copolyamide as defined above, or at least one copolyamide with amide units (Ba1) and polyether units (Ba2), or a mixture of two, relative to the total weight of the third element.

[0240] In the case of a semi-finished product, a step of adding other elements is carried out, which cannot be recycled by the method of the invention, but which are preferably easily separable from the elements of the invention (such as the electronics of a watch).

[0241] According to another aspect, the invention relates to a method for recycling an object as defined above, comprising steps which include the following:

[0242] (a) providing a used object,

[0243] (b) optionally separating the elements of the object which cannot be recycled in the method,

[0244] (c) optionally cleaning the used object from step (a) or (b),

[0245] (d) optionally first grinding the used object from step (a) or (b), or the used object of step (c) when cleaning in step (c), to obtain a first ground material,

[0246] (e) optionally washing the ground material when not performing the cleaning in step (c),

[0247] (f) grinding the used object from step (a) and / or (b) and / or (c) and / or (d) and / or (e) in order to obtain a first ground material or a second ground material when first grinding has been carried out in step (d),

[0248] (g) Heat the ground material from step (f) until it melts.

[0249] (h) Optionally compound and

[0250] (i) Extrude or injection mold the molten material.

[0251] The first and / or second grinding may or may not be carried out before or after cleaning.

[0252] Cleaning is carried out by means of compressed air, especially under pressure, or by means of hot water or steam from the structure.

[0253] Cleaning with compressed air allows non-polymeric particles such as dirt, sand or dust to be removed from the used object.

[0254] Cleaning with hot water or steam allows at least partial dissolution and removal of water-soluble substances of the used object to obtain other constituent elements of the used object.

[0255] The temperature of the hot water or steam is from 70 °C to 150 °C, especially from 70 °C to 120 °C.

[0256] The hot water may have a pH of 1 to 12.

[0257] The compounding step (h) allows the addition of impact modifiers and / or fillers and / or additives and / or plasticizers.

[0258] If step (h) is carried out, the material obtained after said step (h) is in the form of granules for subsequent extrusion or injection molding.

[0259] The term "used object" means an object that is no longer new and that has been used or has been put to use, but in no case does it mean such a post-industrial object that would be recycled without having been used or put to use. Thus, the term "used object" particularly encompasses aged objects.

[0260] In another embodiment, the invention relates to the recycling method as defined above, further comprising the following steps:

[0261] (j) Before or after step (f) or after step (g), add new material to the ground material of the used object.

[0262] The term "new material" means both another polymer, especially another polyamide, especially a polyamide with C / N < 8, and fillers and additives.

[0263] At least one dimension (selected from length, width, and thickness), preferably at least two dimensions (selected from length, width, and thickness), or even all three dimensions, of the single-material object is greater than 1 mm, preferably greater than 2 mm, and advantageously greater than 3 mm. This allows for better recyclability, especially by grinding and / or compounding.

[0264] Regarding additives

[0265] The additives are optional and account for 0 wt% to 20 wt%, especially 0.1 wt% to 5 wt%.

[0266] The additives are selected from dyes, stabilizers, plasticizers, surfactants, nucleating agents, pigments, brighteners, antioxidants, lubricants, flame retardants, natural waxes, impact modifiers, additives for laser marking, and mixtures thereof.

[0267] Regarding fillers

[0268] Regarding fillers, these are reinforcing fibers, which are notably fibers of mineral, organic, or plant origin.

[0269] The reinforcing fibers may or may not be sized.

[0270] Thus, the reinforcing fibers may contain up to 0.1 wt% of a material of organic nature (of the thermosetting or thermoplastic resin type) called a sizing agent.

[0271] Among the fibers of mineral origin, mention may be made, for example, of carbon fibers, glass fibers, basalt fibers or basalt-based fibers, silica fibers, or silicon carbide fibers. Among the fibers of organic origin, mention may be made, for example, of fibers based on thermoplastic or thermosetting polymers, such as semi-aromatic polyamide fibers, aramid fibers, or polyolefin fibers. Preferably, they are based on amorphous thermoplastic polymers, and when the polymer or blend is amorphous, its glass transition temperature Tg is greater than that of the thermoplastic polymer or polymer blend constituting the pre-impregnated matrix, or when the polymer or blend is semi-crystalline, its glass transition temperature Tg is greater than the Tm of the thermoplastic polymer or polymer blend constituting the pre-impregnated matrix. Among the fibers of plant origin, mention may be made of natural fibers based on flax, hemp, lignin, bamboo, silk, especially spider silk, sisal, and other cellulose fibers, especially viscose fibers. For the purpose of promoting the adhesion and impregnation of the thermoplastic polymer matrix, these plant-origin fibers can be used in their pure state, treated, or coated with a coating.

[0272] Preferably, the reinforcing fibers are selected from glass fibers, carbon fibers, basalt fibers, and basalt-based fibers.

[0273] Advantageously, the reinforcing fibers are selected from carbon fibers and glass fibers.

[0274] In one embodiment, the reinforcing fibers present in a) are glass fibers.

[0275] The glass fibers may have a circular or non-circular cross-section.

[0276] Fibers with a circular cross-section are defined as those having an equal distance from the center of the fiber at any point on its circumference, thus representing a perfect or nearly perfect circle.

[0277] Therefore, any glass fiber that does not have such a perfect or nearly perfect circle is defined as a fiber with a non-circular cross-section.

[0278] Examples of fibers with a non-circular cross-section are not limited to non-circular fibers, such as having an oval, egg-shaped or cocoon-shaped, star-shaped fibers, flake-shaped fibers, flat fibers, cross-shaped, polygonal and annular.

[0279] The glass fibers can be:

[0280] - having a circular cross-section with a diameter of 4 μm to 25 μm, preferably 4 μm to 15 μm;

[0281] - or having a non-circular cross-section with an L / D ratio (where L represents the maximum dimension of the cross-section of the fiber and D represents the minimum dimension of the cross-section of the fiber) of 2 to 8, especially 2 to 4. L and D can be measured by scanning electron microscopy (SEM).

[0282] Advantageously, the glass fibers are circular.

[0283] The glass fibers are notably of type E, R, S2 or T. Advantageously, the glass fibers are of type E.

[0284] In another embodiment, the filler is present in an amount of 0 - 65%.

[0285] In one embodiment, the filler is recycled.

[0286] In the case where the filler contains glass, they can notably be made from industrial production waste or post-consumer glass.

[0287] The carbon fibers can, for example, come from the cutting of expired rolls of long fibers, especially carbon fibers for aviation.

[0288] Advantageously, the filler is selected from glass fibers, especially circular glass fibers, and carbon fibers, especially glass fibers, notably circular glass fibers.

[0289] According to another aspect, the present invention relates to a recycled polyamide composition obtainable by the method defined above.

[0290] According to another aspect, the present invention relates to a composition comprising, by weight:

[0291] - 30% to 100%, advantageously 50% to 99%, of recycled polyamide from the single-material object defined above,

[0292] - 0 to 70% of virgin polyamide selected from homopolyamides, especially long-chain homopolyamides, copolyamides, especially long-chain copolyamides, and PEBA, especially long-chain PEBA; advantageously, the virgin polyamide is PEBA, especially long-chain PEBA,

[0293] 0 to 65% of filler,

[0294] 0 to 20 wt%, especially 0.1 wt% to 5 wt%, of additives,

[0295] The sum of the components is equal to 100%,

[0296] The recycled polyamide has functional groups generated by an oxidation reaction, the functional groups being selected from primary amide functional groups, nitriles, chain-end methyl groups, olefins, formamides, imides, carboxylic acids, and alcohols and mixtures thereof, the molar ratio relative to the amide functional groups being greater than that of the same polyamide constituting the unused object that has not been used.

[0297] The term "recycled polyamide derived from the single-material object defined above" is intended to mean a polyamide derived from a single-material object that is no longer new (which has been used or has been in use), but in no case does it mean such a post-industrial object that would be recycled without having been used or without having been in use. In contrast to "virgin" polyamide, "recycled" polyamide particularly encompasses aged polyamide.

[0298] The term "PEBA" is as defined above.

[0299] Throughout the specification, the term "long-chain PEBA" means a copolyamide with amide units (Ba1) and polyether units (Ba2) as defined above, where the polyamide units are long-chain units with a C / N ratio greater than or equal to 8, more particularly greater than or equal to 9, and notably greater than or equal to 10.

[0300] When using a single-material object, new substances generated by an oxidation mechanism are seen in the polyamide constituting the single-material object, especially amide functional groups and / or the alpha-methylene of the amide functional groups, such as imide functional groups, carboxylic acids, primary amides, and alcohols.

[0301] The functional groups are considered to be the result of UV radiation or heat or the reaction of compounds in contact with the object. For example, gasoline, sunscreen, lubricant, etc.

[0302] The functional groups can be detected by infrared or NMR spectroscopy.

[0303] Thus, the absorption band at 1700 to 1740 cm -1 corresponds to imide, the absorption band at 1680 to 1720 cm -1 corresponds to the carbonyl group of carboxylic acid and the absorption band at 3580 to 3670 cm -1 corresponds to the alcohol functional group of carboxylic acid.

[0304] The absorption band at 3580 to 3670 cm -1 corresponds to the free alcohol functional group.

[0305] The amide functional group is first characterized by a pair of absorption bands at 3100 to 3500 cm -1 and 1560 to 1640 cm -1 which correspond to the NH group of amide, and second by the absorption band at 1650 to 1700 cm -1 which corresponds to the carbonyl group of amide.

[0306] In the first variant, the composition comprises, by weight:

[0307] 50% to 70% of recycled polyamide from the single-material objects defined above,

[0308] 30% to 50% of virgin polyamides selected from homopolyamides, especially long-chain homopolyamides, copolyamides, especially long-chain copolyamides, and PEBA, especially long-chain PEBA; advantageously, the virgin polyamide is PEBA, especially long-chain PEBA,

[0309] 0 to 20 wt%, especially 0.1 wt% to 5 wt% of additives,

[0310] The sum of the components is equal to 100%.

[0311] In the second variant, the composition comprises, by weight:

[0312] 30% to 50% of recycled polyamide from the single-material objects defined above,

[0313] 0 to 65% of virgin polyamides selected from homopolyamides, especially long-chain homopolyamides, copolyamides, especially long-chain copolyamides, and PEBA, especially long-chain PEBA; advantageously, the virgin polyamide is PEBA, especially long-chain PEBA,

[0314] 5 to 60% of fillers,

[0315] 0 to 20 wt%, especially 0.1 wt% to 5 wt% of additives,

[0316] The sum of the components is equal to 100%.

[0317] In a third variant, the composition comprises by weight:

[0318] 60% to 80% of recycled polyamide from the recycling of single-material objects as defined above,

[0319] 0 to 20% of virgin polyamides selected from homopolyamides, in particular long-chain homopolyamides, copolyamides, in particular long-chain copolyamides, and PEBA, in particular long-chain PEBA; advantageously, the virgin polyamide is PEBA, in particular long-chain PEBA,

[0320] 20 to 40% of filler,

[0321] 0 to 20% by weight, in particular 0.1% to 5% by weight, of additives,

[0322] The sum of the components is equal to 100%.

[0323] In a fourth variant, the composition comprises by weight:

[0324] 40% to 60% of recycled polyamide from the recycling of single-material objects as defined above,

[0325] 0 to 20% of virgin polyamides selected from homopolyamides, in particular long-chain homopolyamides, copolyamides, in particular long-chain copolyamides, and PEBA, in particular long-chain PEBA; advantageously, the virgin polyamide is PEBA, in particular long-chain PEBA,

[0326] 40 to 60% of filler,

[0327] 0 to 20% by weight, in particular 0.1% to 5% by weight, of additives,

[0328] The sum of the components is equal to 100%.

[0329] In one embodiment, in the compositions of this other aspect and its four variants, the term "comprising" is replaced by the term "consisting of".

[0330] The compositions of these four variants and their embodiments are compositions particularly suitable for embodiments in which the single-material objects as defined above are characterized in that only one of the two compositions contains filler and the other does not contain filler.

[0331] The recycled polyamide has unique characteristics, and when it is derived from the objects as previously defined, it is notable for the new substances produced by the oxidation mechanism.

[0332] For the purposes of the invention, the term "new substances resulting from the oxidation mechanism" is intended to denote the formate (formate ester) functional groups, chain-end methyl groups, primary amides, nitriles, olefins, formamides, carboxylic acids, aldehydes, imides and alcohols visible in the recycled polyamides of the present invention.

[0333] The recycled polyamides of the present invention have functional groups resulting from the oxidation reaction selected from formate functional groups, chain-end methyl groups, primary amides, nitriles, olefins, formamides, carboxylic acids, aldehydes, imides and alcohols.

[0334] According to a preferred embodiment of the present invention, the recycled polyamides of the present invention have functional groups resulting from the oxidation reaction selected from formate functional groups, chain-end methyl groups, primary amides and nitriles.

[0335] According to a preferred embodiment of the present invention, the recycled polyamides of the present invention have functional groups resulting from the oxidation reaction selected from formate functional groups and chain-end methyl groups, the molar ratio thereof relative to the secondary amide functional group being higher than that of the same virgin polyamide.

[0336] These functional groups can be identified and quantified using infrared and / or proton or carbon NMR spectroscopy.

[0337] The NMR measurements can be carried out in a HFIP / CD2Cl2 mixture. For example, 20 mg of the polymer can be dissolved in 0.7 mL of solvent, with a HFIP / CD2Cl2 ratio of 1 / 3. A dichloromethane (CD2Cl2) / trifluoroacetic anhydride (ATFA) mixture can also be used.

[0338] This method is described in Chapter II.2.3 of the doctoral thesis of E. Goncalves published in 2011, which is incorporated herein by reference. Analysis in these two solvents allows the identification of most of the functional groups formed during the lifetime of the polyamide.

[0339] Thus, by way of example, in the infrared spectrum, the absorption band at 1700 to 1740 cm -1 corresponds to imides, the absorption band at 1680 to 1720 cm -1 corresponds to the carbonyl group of carboxylic acids and the absorption band at 3580 to 3670 cm -1 corresponds to the alcohol functional group of carboxylic acids.

[0340] The absorption band at 3580 to 3670 cm -1 corresponds to the free alcohol functional group.

[0341] The amide functional group is characterized firstly by a pair of absorption bands at 3100 to 3500 cm -1 and 1560 to 1640 cm -1 which correspond to the NH group of the amide, and secondly by the absorption band at 1650 to 1700 cm-1 absorption bands corresponding to the carbonyl groups of the amides.

[0342] Absorption bands at 1180 and 1723 cm -1 correspond to formate. Absorption bands at 900 and 1660 cm -1 correspond to alkenes.

[0343] For example, the degradation of polyethers included in polyamide elastomers (especially PEBA) can be quantified by infrared spectroscopy by comparing the band at 1111 cm -1 (vibration of the C-O bond of the ether group) or the band at 2791 cm -1 (CH2 at the α-position of the ether functional group) with the intensity of the band at 1725 cm -1 (carbonyl functional group).

[0344] Quantification is carried out by NMR, for example, in the context of proton NMR by comparing the intensity of the lines of functional groups absent in the unused polymer with the intensity of the lines corresponding to CH2 at the α-position of the amide. In carbon NMR, the intensity of the lines of functional groups formed during the lifetime of the polymer is compared with the intensity of the lines of amide or CH2 carbon.

[0345] For example, some of the above functional groups can be observed in 13C NMR in HFIP / CD2Cl2 solvent. Thus, the line at 36 ppm corresponds to CH2 at the α-position of the primary amide, and the line at 34 ppm corresponds to CH2 at the α-position of the carboxylic acid. These substances can be quantified by integrating the area under this line and comparing it with the area under the line at 37.1 ppm corresponding to the secondary amide. Similarly, lines corresponding to the carbonyl groups of the primary amide, carboxylic acid, and secondary amide functional groups are observed at 181.2 ppm, 179.6 ppm, and 177.4 ppm, respectively. The line at 16.7 ppm corresponds to CH2 at the α-position of the nitrile group. The formamide group gives chemical shifts at 163.0 ppm and 166.3 ppm.

[0346] As described above, in proton NMR in HFIP / CD2Cl2 solvent ( 1Other functional groups mentioned above can be observed in the ¹H NMR. The lines of the formamide CHO group appear at 7.92 and 8.01 ppm. The line corresponding to the CH₂ group at the α-position of the primary amide can be observed at 2.30 ppm. The 0.9 ppm line corresponds to the CH₃ group of the CH₃-(CH₂)ₙ type. The line at 2.40 ppm corresponds to the CH₂ at the α-position relative to the nitrile functional group. The line corresponding to the proton of the formate functional group is observed at 8.1 ppm. The line corresponding to the proton of the aldehyde functional group is observed at 9.7 ppm. Similar to that described for carbon NMR, the ratio of the new functional group relative to the secondary amide can be determined by integrating the area under the line and comparing it with the area under the line corresponding to the CH₂ at the α-position of the secondary amide (2.20 ppm) or with the area under the line corresponding to the CONH proton of the secondary amide (6.0 - 6.1 ppm).

[0347] According to any one of the embodiments of the present invention, in the recycled polyamide of the present invention, the molar ratio of the functional groups generated by the oxidation reaction to the secondary amide functional group is from 0.0005 to 0.3.

[0348] According to any one of the embodiments of the present invention, in the recycled polyamide of the present invention, the molar ratio of the formate functional group to the secondary amide functional group is from 0.0005 to 0.2, particularly from 0.001 to 0.08, particularly from 0.005 to 0.05.

[0349] According to any one of the embodiments of the present invention, in the recycled polyamide of the present invention, the molar ratio of the chain-end methyl to the secondary amide functional group is from 0.0005 to 0.2, particularly from 0.001 to 0.08, particularly from 0.005 to 0.05.

[0350] According to any one of the embodiments of the present invention, in the recycled polyamide of the present invention, the molar ratio of the primary amide functional group to the secondary amide functional group is from 0.0005 to 0.1, particularly from 0.001 to 0.08, particularly from 0.005 to 0.05.

[0351] Needless to say, depending on the waste product and the exposure it has undergone, one or more functional groups generated by the oxidation reaction may be present.

[0352] In one embodiment, the molar ratio of the functional groups generated by the oxidation reaction to the secondary amide functional group is from 1 / 10000 to 1 / 20.

[0353] The concentration can be measured by proton NMR in dichloromethane-d₂, where HFIP (hexafluoroisopropanol) is added to dissolve the polyamide.

[0354] In a first variant, said molar ratio of imide functional groups is from 1 / 1000 to 1 / 20, notably from 1 / 500 to 1 / 20, especially from 1 / 200 to 1 / 50.

[0355] In a second variant, said molar ratio of carboxylic acid functional groups is from 1 / 5000 to 1 / 20, notably from 1 / 3000 to 1 / 50, very advantageously from 1 / 500 to 1 / 15.

[0356] In a third variant, said molar ratio of alcohol functional groups is from 1 / 1000 to 1 / 20, advantageously from 1 / 1000 to 1 / 25, very advantageously from 1 / 200 to 1 / 50.

[0357] In a fourth variant, said molar ratio of primary amide functional groups relative to secondary amide functional groups is from 1 / 2000 to 1 / 20, advantageously from 1 / 1000 to 1 / 100 and very advantageously from 1 / 1000 to 1 / 500.

[0358] In a fifth variant, said molar ratio of nitrile functional groups relative to secondary amide functional groups is from 1 / 1000 to 1 / 20, advantageously from 1 / 500 to 1 / 15 and very advantageously from 1 / 100 to 1 / 10.

[0359] In a sixth variant, said molar ratio of chain - end methyl functional groups relative to secondary amide functional groups is from 1 / 5000 to 1 / 50, advantageously from 1 / 2000 to 1 / 100 and very advantageously from 1 / 1000 to 1 / 200.

[0360] Needless to say, as a function of the used single - material object and the exposure it has undergone, there may be one or more functional groups resulting from oxidation reactions.

[0361] The composition also advantageously contains residues of stabilizers selected from phenols, quinones, stilbene quinones and phosphites.

[0362] The recycled polyamide advantageously contains alkyl chain - ends with a carbon number (between 1 and 18) greater than that of the unused PA. Advantageously, the alkyl chain - end content is from 1 ppm to 0.5%.

[0363] According to another aspect, the invention relates to the use of the composition as defined above for the manufacture of objects, especially single - materials.

[0364] The single - material object thus manufactured from a used single - material object itself can be recycled at least once, especially from 1 to 10 times, according to the method of the invention. Examples

[0365] The following examples illustrate the invention but do not limit it. The shin guards EC1 and EI1 are assembled by overmolding. The percentages shown are mass percentages.

[0366] The following polymers are used to manufacture components:

[0367] - PEBA No.1: A PEBA copolymer comprising a PA 11 block with a number-average molar mass of 1000 g / mol and a flexible PTMG block with a number-average molar mass of 1000 g / mol, and having a Shore D hardness of 40.

[0368] - PEBA No.2: A PEBA copolymer comprising a PA 11 block with a number-average molar mass of 600 g / mol and a flexible PTMG block with a number-average molar mass of 1000 g / mol, and having a Shore D hardness of 35.

[0369] - PEBA No.3: A PEBA copolymer comprising a PA 6 block with an average molar mass of 1500 g / mol and a flexible PEG block with a number-average molar mass of 1500 g / mol, and having a Shore D hardness of 30.

[0370] - TPU No.1: A TPU having rigid blocks based on 4,4'-MDI (4,4'-diphenylmethane diisocyanate) and 1,4-BDO (1,4-butanediol) and flexible polyester blocks of TPU based on adipic acid and butanediol, with a hardness of 85 Shore A.

[0371] - Compo 1 consists of 96 wt% PEBA 1 and 4 wt% PEBA 3.

[0372] The EC1 and EI1 objects are ground to a size smaller than 30 mm and then compounded in an 18 mm twin-screw extruder at a flow rate of 5 kg / h and a temperature of 230 °C to obtain granules for evaluating the properties obtained during the second life of the material.

[0373] Subsequently, the composition is dried at 80 °C under reduced pressure to achieve a moisture content of less than 0.04%.

[0374] A 2 mm plate is manufactured by injection molding using a Battenfeld BA800CDC press and an unpolished mold. The following parameters are applied during injection:

[0375] - Barrel temperature: 180 °C.

[0376] - Nozzle temperature: 200 °C.

[0377] - Mold temperature: 30 °C.

[0378] - Cycle time: 60 seconds.

[0379] After conditioning for 15 days at 50% relative humidity, the density at 23 °C was measured on a 2 mm sheet according to standard ISO 1183-1. The tan δ at 23 °C was measured according to standard ISO 6721 (from 2019), at a tensile strain of 0.1%, a frequency of 1 Hz and a heating rate of 2 °C / min. All these evaluations were carried out on dry (unconditioned) test specimens.

[0380] The compositions and their evaluations are shown in Table 1.

[0381] [Table 1]

[0382]

[0383] It was found that the compositions have a lower tan δ at 23 °C than the comparative compositions and thus have a higher elastic recovery, while maintaining a lower density than the comparative compositions. Thus, the objects of the invention can be recycled to manufacture high-performance components.

[0384] When injection molding ground EC2, high swelling was observed, which is synonymous with incompatibility between the materials present in the composition.

Claims

1. A single-material object comprising at least two components: - At least one first component consisting of a first composition comprising at least 30% by weight, notably at least 50% by weight, particularly at least 70% by weight, more particularly at least 90% by weight of a copolyamide bearing amide units (Ba1) and polyether units (Ba2), relative to the total weight of the first component, - At least one second component consisting of a second composition comprising at least 30% by weight, notably at least 50% by weight, particularly at least 70% by weight, more particularly at least 90% by weight of a copolyamide bearing amide units (Ba1) and polyether units (Ba2), relative to the total weight of the second component, Said first and second components being able to adhere to each other at least in part, The copolyamide of the first composition and / or the copolyamide of the second composition having a C / N ratio of units (Ba1) greater than or equal to 8, particularly greater than or equal to 9, notably greater than or equal to 10.

2. The single-material object according to claim 1, characterized in that, The single-material object is selected from electronic articles, textile articles, optical articles, household electrical articles, cosmetic articles, sports articles, stationery articles, luggage articles, toys, furniture or motor vehicle parts.

3. The single-material object according to claim 1 or 2, characterized in that Only one of the two compositions contains a filler and the other does not contain a filler.

4. The single-material object according to claims 1 to 3, characterized in that At least 10% by weight, particularly at least 30% by weight of the units of at least one polyamide bearing units (Ba1) of the first composition and the polyamide bearing units (Ba1) of the second composition are identical; particularly, said units are PA11 units.

5. The single-material object according to claims 1 to 4, characterized in that, The first composition and the second composition contain the same polyamide units, particularly PA11.

6. A single-material object according to one of claims 1 to 4, characterized in that, Said first and second components are selected from the following constituents: fabrics, films or textured films, foams, injection-molded parts, extruded parts, 3D printed parts, adhesives, non-wovens, meshes and consolidated thermoplastic composite parts, preferably selected from fabrics, foams, injection-molded parts, 3D printed parts, adhesives, non-wovens, meshes and consolidated thermoplastic composite parts.

7. The single-material object according to claim 6, wherein It comprises at least two different constituents as defined in claim 6.

8. The single-material object according to claim 7, characterized in that, It comprises at least three constituents as defined in claim 6, particularly different constituents.

9. The single-material object according to any one of claims 1 to 8, characterized in that, The first component and the second component adhere to each other by bonding by means of a non-polyamide adhesive, the content of the non-polyamide adhesive ranging from 0.01% by weight to 10% by weight, particularly from 0.1% by weight to 4% by weight, relative to the total mass of the object.

10. The single-material object according to any one of claims 1 to 9, characterized in that It comprises at least one third component consisting of a third composition comprising: - At least one long-chain homopolyamide or at least one long-chain copolyamide or at least one copolyamide bearing amide units (Ba1) and polyether units (Ba2) or a mixture thereof, said at least one copolyamide bearing amide units (Ba1) and polyether units (Ba2) being as defined in claim 1.

11. A method for manufacturing a single-material object according to any one of claims 1 to 10, comprising steps involving: Provided is a first element composed of a first composition, the first composition comprising at least 30% by weight, notably at least 50%, particularly at least 70%, more particularly at least 90% of at least one copolyamide having amide units (Ba1) and polyether units (Ba2) as defined in one of claims 1 to 10, relative to the total weight of the first element. Provided is a second element composed of a second composition, the second composition comprising at least 30% by weight, notably at least 50%, particularly at least 70%, more particularly at least 90% of at least one copolyamide having amide units (Ba1) and polyether units (Ba2) as defined in one of claims 1 to 10, relative to the total weight of the second element. Assembling the elements of an object by means of an adhesive, where appropriate, to form a finished or semi-finished object.

12. A method for recycling an object as defined in any one of claims 1 to 10, comprising steps involving: (a) Providing a used object. (b) Optionally separating the elements of the object that are not recyclable in the method. (c) Optionally cleaning the used object from step (a) or (b). (d) Optionally first grinding the used object from step (a) or (b), or the used object from step (c) when cleaning in step (c), to obtain a first ground material. (e) Optionally washing the first ground material when not performing the cleaning in step (c). (f) Grinding the used object from step (a) and / or (b) and / or (c) and / or (d) and / or (e) so as to obtain a first ground material or a second ground material in the case where the first grinding in step (d) has been carried out. (g) Heating the ground material from step (f) until it melts. (h) Optionally compounding and (i) Extruding or injection molding the molten material.

13. The recycling method according to claim 12, further comprising the following step: (j) Adding new material to the ground material of the used object before or after step (f) or after step (g).

14. A recycled polyamide composition obtainable by the method according to claims 12 to 13.

15. A composition which, based on weight, comprises: 30% to 100%, advantageously 50% to 99% of recycled polyamide from the single-material objects defined above. 0 to 70% of unused polyamides selected from homopolyamides, particularly long-chain homopolyamides, copolyamides, particularly long-chain copolyamides, and PEBA; advantageously, the unused polyamide is PEBA. 0 to 65% of fillers. 0 to 20%, particularly 0.1% to 5% of additives. The sum of the components is equal to 100%. The recycled polyamide has functional groups generated by an oxidation reaction, the functional groups being selected from primary amide functional groups, nitriles, chain-end methyl groups, olefins, formamides, imides, carboxylic acids, and alcohols and mixtures thereof, and the molar ratio of the functional groups to amide functional groups is greater than the molar ratio of the same polyamide constituting the unused object that has not been used.

16. The composition according to claim 15, wherein The molar ratio of the functional group derived from the oxidation reaction to the secondary amide functional group is from 1 / 10,000 to 1 / 20.

17. The composition according to claim 15 or 16, characterized in that The molar ratio of the imide functional group to the secondary amide functional group is from 1 / 1,000 to 1 / 20, in particular from 1 / 500 to 1 / 20, in particular from 1 / 200 to 1 / 50.

18. The composition according to any one of claims 15 to 17, characterized in that The molar ratio of the carboxylic acid functional group to the secondary amide functional group is from 1 / 5,000 to 1 / 20, and in particular from 1 / 3,000 to 1 / 50, very advantageously from 1 / 500 to 1 / 15.

19. A composition according to any one of claims 15 to 18, characterized in that The molar ratio of the alcohol functional group to the secondary amide functional group is from 1 / 1,000 to 1 / 20, advantageously from 1 / 1,000 to 1 / 25, and very advantageously from 1 / 200 to 1 / 50.

20. The composition according to any one of claims 15 to 19, characterized in that The molar ratio of the primary amide functional group to the secondary amide functional group is from 1 / 2,000 to 1 / 20, advantageously from 1 / 1,000 to 1 / 100, and very advantageously from 1 / 1,000 to 1 / 500.

21. The composition according to any one of claims 15 to 20, characterized in that The molar ratio of the nitrile functional group to the secondary amide functional group is from 1 / 1,000 to 1 / 20, advantageously from 1 / 500 to 1 / 15, and very advantageously from 1 / 100 to 1 / 10.

22. The composition according to any one of claims 15 to 21, characterized in that The molar ratio of the terminal methyl functional group to the secondary amide functional group is from 1 / 5,000 to 1 / 50, advantageously from 1 / 2,000 to 1 / 100, and very advantageously from 1 / 1,000 to 1 / 200.

23. Use of a composition according to any one of claims 14 to 22 for the manufacture of an object, in particular a single-material object.

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