WO2024089369A1

WO2024089369A1 - Recyclable single-material objects comprising at least two elements

Info

Publication number: WO2024089369A1
Application number: PCT/FR2023/051691
Authority: WO
Inventors: Thomas PRENVEILLE; Karine Loyen; Amélie NOEL; Patrick Dang
Original assignee: Arkema France
Priority date: 2022-10-28
Filing date: 2023-10-26
Publication date: 2024-05-02
Also published as: FR3141468A1

Abstract

The present invention relates to a single-material object comprising at least two elements: at least one first element consisting of a first composition comprising, relative to the total weight of the first element, at least 30 wt% of at least one homopolyamide or at least one long-chain copolyamide, wherein a copolyamide with amide units (Ba1) and polyether units (Ba2) is excluded from the first composition, at least one second element consisting of a second composition comprising, relative to the total weight of the second element, at least 30wt% of at least one homopolyamide or at least one long-chain copolyamide, wherein a copolyamide with amide units (Ba1) and polyether units (Ba2) is excluded from the second composition, the first and second elements being able to adhere at least partially to one another, the at least one homopolyamide or at least one copolyamide, preferably the at least one homopolyamide or at least one majority copolyamide, of the first composition and/or the at least one homopolyamide or at least one copolyamide, preferably the at least one homopolyamide or at least one majority copolyamide, of the second composition having a C/N ratio greater than or equal to 8, wherein the object should not include a single-layer or multilayer structure for the transport, distribution or storage of a fluid.

Description

DESCRIPTION

TITLE: Recyclable single-material objects comprising at least two elements [Technical field]

The present patent application concerns recyclable mono-material objects comprising at least two elements, their manufacturing process as well as their recycling process and the compositions thus obtained as well as their use for the manufacture of objects, in particular mono-materials.

[Prior art]

The circular economy makes it possible to limit waste production, the depletion of the planet's resources and environmental impact. We are currently seeking in particular to produce objects using materials which will have sufficient properties after recycling to allow their use for high performance applications and not only for lower performance applications such as street furniture or roads.

In the context of sustainable consumption and production patterns, the suitability for recycling of frequently replaced items such as sporting goods and E&E articles and the quality of the resulting recycling products is of particular importance. However, the performance requirements are particularly high for these articles.

It is essential to design items such as sporting goods and E&E items so that they can be recycled to produce a material with high performance. It is also important that the products used to make objects are stable enough to be recycled safely. When thermoplastic polyurethanes (TPU) are recycled, the formation of isocyanate can be observed in FTIR. Isocyanates are dangerous compounds, CMR...

Patent EP 3 081 109 B1 proposes, in order to facilitate their recycling, a sports shoe whose upper part and sole are mainly or even entirely made up of the same thermoplastic base material. However, it appears that there remain difficulties in that the recycling product thus obtained has limits in terms of performance due to the fact that the density of the shoe parts differs depending on their respective function.

Patent application WO 2020/201370 Al proposes a method for recycling such shoes in which the shoe is crushed and then melted. This document focuses, like the previous one, on thermoplastic polyurethanes (TPU). This international application indicates that TPU degrades with recycling cycles.

Application US 2017/0151470 Al concerns a ball, in particular a football, a manufacturing process and the recycling of the ball. The balloon consists of a bladder, an intermediate layer and an outer layer, the bladder and the two layers consisting of a majority component by weight of a material of a first class of material chosen from polyurethane, polyvinyl chloride, polyethylene, polyamide and polypropylene.

International application WO 2021/148148 Al relates to a lined article of clothing which comprises an outer layer, an inner layer and a lining between the two layers. Each layer contains a majority of a material from the same family chosen from thermoplastic polymers, in particular a recycled polyester or a virgin polymer chosen from thermoplastic polyurethanes (TPU), polyamides (PA), polyethylene terephthalate (PET ) or polybutylene terephthalate (PBT). Polyesters have the disadvantage of being very sensitive to hydrolysis.

The invention therefore aims to propose a mono-material object whose composition is studied so as to enable the recycling of a composition capable of being used for applications requiring high performance.

However, it has been demonstrated that the exclusive combination (excluding additives and fillers) in a mono-material object of a polyamide fraction (element) and a polyamide fraction (element) allows better maintenance of properties during recycling.

In particular, impact resistance, fatigue resistance and mechanical properties (modulus, elongation at break, break stress and threshold) are maintained. In addition, density and chemical resistance are maintained.

Indeed, the presence in the composition of polyamides provides in particular good resistance to aging and therefore to the life of the object and its recycling process.

Also, according to a first aspect, the invention relates to a single-material object comprising at least two elements:

- at least one first element consisting of a first composition comprising by weight at least 30%, in particular at least 50%, particularly at least 70%, more particularly at least 90%, relative to the total weight of the first element, at least one homopolyamide or at least one copolyamide, said at least one homopolyamide and said at least one copolyamide independently representing a repeating unit chosen from a unit obtained from the polycondensation of at least one amino acid, a unit obtained from the polycondensation of at least one lactam and an XY unit obtained from the polycondensation of: at least one diamine, said diamine being chosen from a linear or branched aliphatic diamine, a cycloaliphatic diamine and a semi-arylaliphatic diamine or a mixture thereof, and at least one dicarboxylic acid, said diacid being chosen from: an aliphatic diacid, a cycloaliphatic diacid and an aromatic diacid, said diamine and said diacid comprising from 4 to 36 carbon atoms, advantageously from 6 to 18 carbon atoms, a copolyamide with amide units (Bal) and polyether units (Ba2) being excluded from said first composition,

- at least one second element consisting of a second composition comprising by weight at least 30%, in particular at least 50%, particularly at least 70%, more particularly at least 90%, relative to the total weight of the second element, at least one homopolyamide or at least one copolyamide, said at least one homopolyamide and said at least one copolyamide being as defined above for the first composition, a copolyamide with amide units (Bal) and polyether units (Ba2) being excluded from said second composition, said first and second elements being able to adhere at least partially to each other, said at least one homopolyamide or at least one copolyamide, preferably said at least one homopolyamide or at least one majority copolyamide, of the first composition and/or said at least one homopolyamide or at least one copolyamide, preferably said at least one homopolyamide or at least one majority copolyamide, of the second composition having a C/N ratio greater than or equal to 8, in particular greater than or equal to 9, in particular greater than or equal to 10, said object being excluding a single-layer or multi-layer structure for the transport, distribution or storage of a fluid.

The inventors have therefore unexpectedly found that the exclusive combination (excluding additives) in a mono-material object of a particular polyamide fraction (or element), namely long-chain polyamides and a polyamide fraction (or element) particular, namely long-chain polyamides, allows better maintenance of properties during recycling.

Indeed, the long-chain polyamides in the two compositions present the best compromise and notably provide good resistance to aging and therefore to the life of the object and its recycling process. They can also be recycled safely.

The recycled compositions also have the advantage of having a low density, good elastic return, good fatigue resistance, good impact resistance, good mechanical properties in traction, good dimensional stability, as well as a good chemical resistance, in particular good resistance to hydrolysis.

The C/N ratio corresponds to the number of carbon atoms per nitrogen atom in the polyamide or copolyamide.

By “mono-material object” we must understand an object made up mainly of the same material, in this case a long-chain polyamide. More precisely, by “mono-material object”, it is necessary to understand an object comprising at least two elements, with each element being made up of compositions respectively comprising at least one polymeric matrix, with said polymeric matrix mainly comprising, that is to say say more than 50% by weight, relative to its total weight, at least one homopolyamide and/or at least one long-chain copolyamide as defined according to the invention.

Within the meaning of the invention, the mono-material object may in particular be an object comprising at least two elements, with each element being mono-material, that is to say each element being made up mainly of the same material such as defined according to the invention. By “polymeric matrix” we mean the part of the composition consisting exclusively of polymers, that is to say that non-polymeric fillers and additives are excluded here.

Preferably said polymer matrix comprises at least 60% by weight, preferably 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 homopolyamide and/or at least one long-chain copolyamide as defined according to the invention.

According to one embodiment, a “mono-material object” within the meaning of the invention is an object comprising at least two elements, with at least one element, preferably each element, being made up of compositions comprising mainly, i.e. that is to say more than 50% by weight, relative to their total weight, at least one homopolyamide and/or at least one long-chain copolyamide as defined according to the invention.

Preferably at least one element, preferably each element, consists of compositions 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 at least one homopolyamide and/or at least one long-chain copolyamide as defined according to the invention

According to one embodiment, a mono-material object of the invention is an object comprising at least two elements, with at least one element, preferably each element, being made up of compositions comprising less than 20% by weight, preferably less 10% by weight, for example less than 5% by weight, for example less than 3% by weight, in particular 0% by weight, relative to their total weight, of short-chain polyamides, i.e. say polyamides having a C/N ratio strictly less than 8, in particular less than or equal to 7, in particular less than or equal to 6.

According to one embodiment, a mono-material object of the invention comprises 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, in particular 0% by weight, relative to its total weight, of short-chain polyamides, that is to say polyamides having a C/N ratio strictly less than 8, in particular less than or equal to 7, in particular less or equal to 6. In a first variant, the mono-material objects can be without being limited to these: An electronic article, in particular a watch, a telephone case, headphones, earphones, a speaker, a keyboard, a mouse, a phone charger, an article of clothing, in particular a jacket, trousers, a t-shirt, socks an optical article, in particular glasses, sunglasses, children's glasses, sports glasses and a ski mask, augmented reality/virtual reality glasses.

A household appliance item, in particular a small household appliance, a household appliance accessory (bowl, mixing paddle, food container), a water bottle, a food container, a cosmetic item, in particular cosmetic packaging such as a bottle , a perfume, makeup packaging, skincare packaging, a presentation item, a hairbrush, a sporting item, in particular a surfboard (and its accessories such as a leash) or fins), a bicycle, bicycle item such as saddle or pedal, a helmet, a ski boot, skis, 5 ski poles, a ski binding and a snowboard (excluding metal), a golf club, any type of racket in particular a tennis racket, protective equipment such as shin guard, elbow pad, etc., a hockey stick (on grass and ice), a roller, diving fins, an item of luggage, in particular a suitcase, backpack and handbag stationery, especially pens.

A toy, furniture, and automobile parts

(excluding a single-layer or multi-layer structure for the transport, distribution or storage of a fluid).

The expression "said object being excluding a single-layer or multi-layer structure for the transport, distribution or storage of a fluid" means that single-layer or multi-layer structures for the transport, distribution or storage of a fluid, in particular for a device with a thermal or electric engine such as an airplane, a drone, an aircraft, a truck or an automobile are excluded from said object.

In one embodiment of this first variant, the mono-material objects correspond to all those described in the list of this first variant with the exception of at least one of those described in this same list and excluding of a single-layer or multi-layer structure for the transport, distribution or storage of a fluid.

It is obvious that at least, said mono-material object corresponds to at least one of those described in said list of this first variant. In a second variant, the mono-material objects can be an electronic article, a textile article, an optical article, a household appliance article, a cosmetic article, a sporting article, a stationery article, an article of luggage, a toy, furniture and automobile parts (excluding a single-layer or multi-layer structure for the transport, distribution or storage of a fluid).

In one embodiment of this second variant, the mono-material objects correspond to all those described in the list of this second variant with the exception of at least one of those described in this same list and excluding of a single-layer or multi-layer structure for the transport, distribution or storage of a fluid.

It is obvious that at least, said mono-material object corresponds to at least one of those described in said list of this second variant.

In a third variant, the mono-material objects can be an electronic article, a textile article, an optical article, a household appliance article, a cosmetic article, a sporting article, a stationery article, an article of luggage, a toy, furniture.

In one embodiment of this third variant, the mono-material objects correspond to all those described in the list of this third variant with the exception of at least one of those described in this same list and excluding of a single-layer or multi-layer structure for the transport, distribution or storage of a fluid.

It is obvious that at a minimum, said mono-material object corresponds to at least one of those described in said list of this third variant.

Said object is excluding a single-layer or multi-layer structure for the transport, distribution or storage of a fluid.

The term “fluid” includes any gas, in compressed form, in liquid form or even cryocompressed, and in particular hydrogen, natural gas, LPG, LNG, compressed air, nitrogen, oxygen, as well as a heat transfer fluid, in particular a refrigerant chosen from hydrocarbon compounds, hydrofluorocarbons, ethers, hydrofluoroethers, CO2, NH3, SO2 and fluoroolefins, in particular R134, R-1234yf or R-1234ze, in particular R-1234yf or R-1234ze, or even a gas used in automobiles, in particular air or a liquid used in automobiles, in particular water, an oil, a brake fluid, a urea solution, a coolant based on glycol, a transmission oil cooler (TOC), fuels, in particular diesel, gasoline, more particularly alcoholic gasoline or LPG.

In one embodiment, a shoe, a ball, a backpack, an automobile seat, a toothbrush or a jacket are excluded from the mono-material objects of the invention.

Preferably, the invention relates to single-material objects capable of being obtained by injection. In one embodiment, at least 50% by weight, preferably more than 50% by weight, of long-chain polyamide or long-chain copolyamide is present in at least one element, preferably in each of the two elements, e.g. relative to the total weight of the composition of each element.

In another embodiment, the matrix of each of the two elements (fillers and additives excluded) consists of 60% by weight, advantageously 80% by weight, preferably 100% by weight of long-chain polyamide or long-chain copolyamide. chain.

The term “element” designates each of the things whose combination, the union forms another thing, a whole, namely in the present invention a mono-material object.

In particular, an element designates a component, a component, a constituent, a piece, a part, a piece or unit which constitutes the mono-material object.

The expression “said first and second elements being able to adhere at least partially to one another” means that said first and second elements may or may not adhere to one another.

In one embodiment, said first and second elements do not adhere to each other.

In another embodiment, said first and second elements adhere to each other, at least partially, in particular completely.

The term “adheres” means that said first and second elements are attached to each other or applied against each other, at least partially and in particular by gluing, clipping, overmolding, thermoforming, screwing, sewing, welding or riveting.

It is obvious that said first and second compositions which comprise a homopolyamide and a long-chain copolyamide can also comprise impact modifiers and/or plasticizers and/or fillers and/or additives.

It is obvious that said third composition described below which comprises a homopolyamide and a long-chain copolyamide or a copolyamide with amide units (Bal) and polyether units (Ba2) or a mixture of the two, can also include impact modifiers. and/or plasticizers and/or fillers and/or additives.

Regarding the long-chain homopolyamide and copolyamide of the compositions of the first, second and third elements.

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

Said long-chain homopolyamide and copolyamide is a polyamide having a C/N ratio, that is to say having an average number of carbon atoms per nitrogen atom greater than or equal to 8, in particular greater than or equal to 9, in particular greater than or equal to 10. In a first variant of the invention, the repetitive unit is a unit obtained from the polycondensation of at least one C4-C36 amino acid (or aminocarboxylic acid). Advantageously, said aminocarboxylic acid comprises from 9 to 12 carbon atoms. . It can thus be chosen from 9-aminononanoic acid (noted 9), 10-aminodecanoic acid (noted 10), 11-aminoundecanoic acid (noted 11) and 12-aminododecanoic acid (noted 12), advantageously the aminocarboxylic acid is 11-aminoundecanoic acid.

In a second variant of the invention, the repetitive unit is a unit obtained from the polycondensation of at least one C4-C36 lactam.

Advantageously, the lactam comprises 9 to 12 carbon atoms. It can thus be chosen from decanolactam (noted 10), undecanolactam (noted 11) and laurolactam or lauryllactam (noted 12), advantageously the lactam is lauryllactam.

However, it is entirely possible to envisage using a mixture of two or more aminocarboxylic acids, a mixture of two or more lactams, but also a mixture of one, two or more aminocarboxylic acids with one, two or more lactams.

More particularly preferably, the repeating unit is obtained from a single aminocarboxylic acid or a single lactam.

XY repeating pattern

The repeating unit XY is a unit obtained from the polycondensation of at least one diamine, said diamine being chosen from a linear or branched aliphatic diamine, a cycloaliphatic diamine and a semi-arylaliphatic or a mixture thereof, and d at least one dicarboxylic acid, said diacid being chosen from: an aliphatic diacid, a cycloaliphatic diacid and an aromatic diacid or a mixture of these,

The molar proportions of diamine and dicarboxylic acid are preferably stoichiometric.

Said diamine comprises from 4 to 36 carbon atoms, advantageously from 6 to 18 carbon atoms.

In one embodiment, said diamine comprises 6 to 12 carbon atoms.

In the case where the diamine used to obtain this repeating XY unit is an aliphatic diamine which has a linear main chain, this linear main chain may, where appropriate, comprise one or more methyl and/or ethyl substituent(s). ; in this last configuration, we speak of "branched aliphatic diamine". In the case where the main chain does not contain any substituent, the aliphatic diamine is called "linear aliphatic diamine". Whether or not it contains methyl and/or ethyl substituents on the main chain, the aliphatic diamine used to obtain this repeating XY unit comprises from 4 to 36 carbon atoms, advantageously from 6 to 18 carbon atoms, in particular from 9 to 18 carbon atoms.

When this diamine is a linear aliphatic diamine, it then corresponds to the formula H2N- (CH2)x-NH2 and can be chosen for example from butanediamine, pentanediamine, hexanediamine, heptanediamine, octanediamine, nonanediamine , decanediamine, undecanediamine, dodecanediamine, tridecanediamine, tetradecanediamine, hexadecanediamine, octadecanediamine and octadecenediamine. The linear aliphatic diamines which have just been mentioned can all be bio-resourced within the meaning of the ASTM D6866 standard.

When this diamine is a branched aliphatic diamine, it may in particular be 2-methylpentanediamine, 2-methyl-1,8-octanediamine or trimethylene (2,2,4 or 2,4,4)hexanediamine. The cycloaliphatic diamine can be chosen 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-methyl-4-aminocyclohexyl)-methane or 3'-dimethyl-4,4'- diamino-dicyclohexyl-methane commonly referred to as "BMACM" or "MACM" (and denoted B below), p-bis(aminocyclohexyl)-methane commonly referred to as "PACM" (and denoted P below), isopropylidenedi( cyclohexylamine) commonly referred to as "PACP", isophorone-diamine (denoted IPD below) and 2,6-bis(amino methyl)norbornane commonly referred to as "BAMN" or bis(aminomethyl)cyclohexane commonly referred to as "BAC".

A non-exhaustive list of these cycloaliphatic diamines is given in the publication “Cycloaliphatic Amines” (Encyclopaedia of Chemical Technology, Kirk-Othmer, 4th Edition (1992), pp. 386-405).

When this diamine is a semi-arylaliphatic diamine, it is for example chosen from 1,3-xylylene diamine and 1,4-xylylene diamine.

The dicarboxylic acid comprises from 4 to 36 carbon atoms, advantageously from 6 to 18 carbon atoms, in particular from 6 to 12 carbon atoms.

When the dicarboxylic acid is aliphatic, it can be chosen from aliphatic, linear or branched dicarboxylic acids

When the dicarboxylic acid is aliphatic and linear, it can be chosen from succinic acid (4), pentanedioic acid (5), adipic acid (6), heptanedioic acid (7), acid octanedioic acid (8), azelaic acid (9), sebacic acid (10), undecanedioic acid (11), dodecanedioic acid (12), brassylic acid (13), tetradecanedioic acid ( 14), hexadecanedioic acid (16), octadecanedioic acid (18), octadecanedioic acid (18), eicosanedioic acid (20), docosanedioic acid (22) and fatty acid dimers containing 36 carbons.

The fatty acid dimers mentioned above are dimerized fatty acids obtained by oligomerization or polymerization of unsaturated monobasic fatty acids with a long hydrocarbon chain (such as linoleic acid and oleic acid), as described in particular in the document EP 0471566.

When the dicarboxylic acid is aromatic, it can be chosen from terephthalic acid (denoted T), isophthalic acid (denoted I) and a naphthalenic acid (denoted N).

In one embodiment, the composition of the first element and that of the second element each consist of a single homopolyamide.

In another embodiment, the homopolyamide of the composition of the first element and that of the second element is an aliphatic semi-crystalline homopolyamide.

A semi-crystalline homopolyamide, within the meaning of the invention, designates a material that is generally solid at room temperature, and which softens upon an increase in temperature, in particular after passing its glass transition temperature (Tg), and which can present a clear melting when passing its so-called melting temperature (Tf), and which becomes solid again when the temperature drops below its crystallization temperature.

The semi-crystalline homopolyamide, within the meaning of the invention, has a melting temperature (Tf) measured according to standard ISO 11357-3:2013 by DSC, and an enthalpy of crystallization measured during the cooling step at a speed of 20K/min by DSC according to standard ISO 11357-3 of 2013 greater than 25 J/g, preferably greater than 40 J/g.

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

The number average molecular mass Mn of said semi-crystalline homopolyamide is preferably in a range going from 10,000 to 85,000, in particular from 10,000 to 60,000, preferably from 10,000 to 50,000, even more preferably from 12,000 to 50,000. These Mn values can correspond at inherent viscosities greater than or equal to 0.8 as determined in m-cresol according to standard ISO 307:2007 but by changing the solvent (use of m-cresol in place of sulfuric acid and the temperature being 20°C).

The inherent viscosities of the at least one homopolyamide or of the at least one copolyamide are comprised from 0.8 to 2, preferably from 1 to 1.8, advantageously from 1.2 to 1.6.

The use of homopolyamides and/or copolyamides of specific inherent viscosity, namely between 0.8 and 2, preferably between 1 and 1.8, preferably between 1.2 and 1.6, advantageously makes it possible to obtain mono-material objects according to the invention having good mechanical properties. It has also been discovered, advantageously, that the use of homopolyamides and/or copolyamides of specific inherent viscosity, namely between 0.8 and 2, preferably between 1 and 1.8, preferably between 1.2 and 1.6, in at least two constituent elements of a mono-material object of the invention, with said elements being adjacent within said mono-material of the invention, also makes it possible to improve, or even to maximize the adhesion between these elements. This makes it possible to reduce the quantity of adhesive necessary for the assembly of these elements, or even to eliminate the presence of adhesive, which further increases the recyclability of said mono-material.

Said at least one homopolyamide or said at least one copolyamide comprise reactive functions chosen from primary amines or carboxylic acids.

Said at least one homopolyamide or said at least one copolyamide preferably has an amine function concentration (NH2) of 0.020 meq/g to 2.0 meq/g, preferably of 0.035 meq/g to 0.5 meq/g , more preferably from 0.040 to 0.2 meq/g. The NH2 function concentration can be measured using a potentiometric assay. This dosage can for example be carried out as follows: the PA are first dissolved in m-cresol at 80°C then the terminal NH2 functions are determined using a perchloric acid solution.

Said at least one homopolyamide or said at least one copolyamide preferably has a COOH function concentration of 0.020 meq/g to 2.0 meq/g, preferably of 0.035 meq/g to 0.5 meq/g, so as to more preferred from 0.040 to 0.2 meq/g. The concentration in COOH function can be determined by potentiometric analysis. A measurement protocol is detailed in the article “Synthesis and characterization of poly(copolyethers-block-polyamides)

- IL Characterization and properties of the multiblock copolymers”, Maréchal et al., Polymer, Volume 41, 2000, 3561-3580.

In one embodiment, when the at least one homopolyamide or the at least one copolyamide of a first element (for example element 1) has an NH2/COOH molar ratio less than 1, the at least one homopolyamide or the at least one least one copolyamide of a second element, preferably of a second element adjacent to said first element (for example element 2, preferably adjacent to element 1) has an NH2/COOH molar ratio greater than 1.

It has also been discovered, advantageously, that the use of homopolyamides and/or copolyamides as defined above in at least two constituent elements of a mono-material object of the invention, with said elements being adjacent within said mono-material of the invention, makes it possible to improve, or even maximize, the adhesion between these elements. This makes it possible to reduce the quantity of adhesive necessary for the assembly of these elements, or even to eliminate the presence of adhesive, which further increases the recyclability of said mono-material. Without being bound by a theory, the implementation of homopolyamides and/or copolyamides as defined above in at least two constituent elements of a mono-material object of the invention can result in chemical reactions between said homopolyamides and/or copolyamides of the first and second elements, in particular when said first and second elements are adjacent, leading to the establishment of covalent chemical bonds between on the one hand homopolyamides and/or copolyamides of said first element and on the other hand, homopolyamides and/or copolyamides of said second element. In a first variant, the first and the second composition of the two elements are different. By different, it must be understood that either the homopolyamide or the copolyamide of the first composition is different from that of the second composition, or the homopolyamide or the copolyamide are identical but in this case, the compositions differ by a constituent other than the polyamide.

Advantageously, in the latter case, only one of the two compositions includes a filler, the other being devoid of it.

In a second variant, the first composition and the second composition comprise the same polyamide, in particular a PA11.

In a third variant at least 10% by weight of the units, in particular at least 30% by weight, constituting said at least one homopolyamide or said at least one copolyamide of the first composition and the second composition are identical, in particular said units are PA11 patterns.

In one embodiment of these three variants, said long-chain homopolyamide is chosen from: polyamide 11 (PA11), polyamide 12 (PA12), polyamide 1010 (PA1010), polyamide 1012 (PA1012), polyamide 1212 (PA1012), or a mixture thereof or a copolyamide thereof, in particular PA11 and PA12.

More particularly, said long-chain homopolyamide is chosen from: polyamide 11 (PA11), polyamide 12 (PA12), polyamide 1012 (PA1012), polyamide 1212 (PA1012), polyamide B12, polyamide PACM12, or a mixture of these, in particular PA11 and PA12. Even more particularly, said long-chain homopolyamide is polyamide 11.

In another embodiment of these three variants, said long-chain copolyamide is chosen from 11/10T, 11/BI, 11/B10, 11/BI/BT, 12/BI, 1010/B10 or a mixture of these. this.

B corresponds to 3,3'-dimethyl-4,4'-diamino-dicyclohexyl-methane commonly also called BMACM or MACM.

PACM corresponds to bis(p-aminocyclohexyl)-methane commonly also called P. PACM is preferably PACM20 which is a mixture of isomers and contains approximately 20% of the trans-trans-PACM isomer or PACM50 which is a mixture of isomers and contains approximately 50% of the trans-trans-PACM isomer .

In one embodiment, said first and second element are chosen from the following constituents: a textile, a film or textured film, a foam, an injected part, an extruded part, a 3D printed part, an adhesive, a non-woven , a veil and a part in consolidated thermoplastic composite.

In another embodiment, said mono-material object defined above is characterized in that it comprises at least two constituents defined above and which are different.

In yet another embodiment, said mono-material object as defined above is characterized in that it comprises at least three constituents defined above, in particular different.

As indicated above, the first element and the second element can adhere at least partially to each other.

According to one embodiment, when they adhere to each other at least partially, the first and the second element adhere to each other by bonding by means of a non-polyamide adhesive in a content comprised of 0.01% to 10% by weight, in particular from 0.1% to 4% by weight relative to the total mass of the object.

Said adhesive can be a polyurethane, acrylic, acrylonitrile, polyester, polyisoprene, polybutadiene, vinyl adhesive, preferably it is chosen from a polyurethane, acrylic and polyester adhesive, advantageously it corresponds to a polyurethane adhesive.

According to another embodiment, when they adhere to each other at least partially, the first and the second element adhere to each other by bonding by means of a polyamide adhesive in a content comprised of 0.01% to 10% by weight, in particular from 0.1% to 4% by weight relative to the total mass of the object.

According to yet another embodiment, when they adhere to each other at least partially, the first and the second element adhere directly to each other, that is to say without adhesive. The embodiments according to which (i) either the first and the second element adhere to each other by bonding by means of a polyamide adhesive (ii) or the first and the second element adhere directly, without adhesive, are particularly advantageous insofar as the recyclability of said mono-material of the invention is thus improved.

Said mono-material object defined above may comprise at least a third element consisting of a third composition comprising at least one homopolyamide or at least one long-chain copolyamide or at least one copolyamide with amide units (Bal) and polyether units (Ba2) or a mixture thereof, the said at least one homopolyamide or at least one long-chain copolyamide being as defined above.

Regarding copolyamide with amide units (Bal) and polyether units (Ba2) (PEBA)

The definition below is valid both for the PEBA excluded from the compositions of the first and second elements and for the PEBA possibly present in the composition of the third element.

Poly ether block amide (PEBA) are copolymers with amide units (Bal) and polyether units (Ba2), said amide unit (Bal) corresponding to an aliphatic repeating unit chosen from a unit obtained from at least one amino acid or an pattern obtained from at least one lactam, or an X.Y pattern obtained from polycondensation:

- at least one diamine, said diamine being preferably chosen from a linear or branched aliphatic diamine or a mixture of these, and

- at least one dicarboxylic acid, said diacid being preferably chosen from: a linear or branched aliphatic diacid, or a mixture thereof, said diamine and said diacid comprising from 4 to 36 carbon atoms, advantageously from 6 to 18 carbon atoms; said polyether units (Ba2) being in particular derived from at least one polyalkylene ether polyol, in particular a polyalkylene ether diol,

PEBAs result in particular from the copolycondensation of polyamide sequences with reactive ends with polyether sequences with reactive ends, such as, among others:

1) Polyamide sequences with diamine chain ends with polyoxyalkylene sequences with dicarboxylic chain ends.

2) Polyamide sequences with dicarboxylic chain ends with polyoxyalkylene sequences with diamine chain ends obtained by cyanoethylation and hydrogenation of aliphatic alpha-omega dihydroxylated polyoxyalkylene sequences called polyalkylene ether diols (polyetherdiols).

3) Polyamide sequences with dicarboxylic chain ends with polyetherdiols, the products obtained being, in this particular case, polyetheresteramides. The copolymers of the invention are advantageously of this type.

Polyamide sequences with dicarboxylic chain ends come, for example, from the condensation of polyamide precursors in the presence of a chain-limiting dicarboxylic acid.

Polyamide sequences with diamine chain ends come for example from the condensation of polyamide precursors in the presence of a chain-limiting diamine. Polyamide block and polyether block polymers can also include randomly distributed units. These polymers can be prepared by the simultaneous reaction of the polyether and the precursors of the polyamide blocks.

For example, polyetherdiol, polyamide precursors and a chain-limiting diacid can be reacted. We obtain a polymer essentially having polyether blocks, polyamide blocks of very variable length, but also the different reagents having reacted randomly which are distributed randomly (statistically) along the polymer chain.

Polyetherdiamine, polyamide precursors and a chain-limiting diacid can also be reacted. We obtain a polymer essentially having polyether blocks, polyamide blocks of very variable length, but also the different reagents having reacted randomly which are distributed randomly (statistically) along the polymer chain.

Amide pattern (Bal):

The amide unit (Bal) corresponds to an aliphatic repeating unit as defined above. Advantageously, the amide unit (Bal) is chosen 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, in particular polyamide 11.

More advantageously, the amide unit (Bal) is chosen from polyamide 11 and polyamide 12, in particular polyamide 11.

Polyether pattern (Ba2):

The polyether units are in particular derived from at least one polyalkylene ether polyol, in other words, the polyether units consist of at least one polyalkylene ether polyol. In this embodiment, the expression "at least one polyalkylene ether polyol" means that the polyether units are exclusively made up of alcohol chain ends and cannot therefore be a compound of the polyetherdiamine triblock type.

The composition of the invention is therefore devoid of polyetherdiamine triblock.

Advantageously, the polyether units (Ba2) are chosen from polyethylene glycol (PEG), polypropylene glycol (PPG), polytrimethylene glycol (PO3G), polytetramethylene glycol (PTMG) and their mixtures or their copolymers, in particular PTMG.

The number average molecular mass (Mn) of the polyether blocks is advantageously between 200 and 4000 g/mole, preferably between 250 and 2500 g/mole, in particular between 300 and 1100 g/mole.

PEBA can be prepared by the following process:

- in a first step, the polyamide blocks (Bal) are prepared by polycondensation of the lactam(s), or the amino acid(s), or the diamine(s) and the dicarboxylic acid(s); and where appropriate, the comonomer(s) chosen from lactams and alpha-omega aminocarboxylic acids; in the presence of a chain limiter chosen from dicarboxylic acids; Then

- in a second step, the polyamide blocks (Bal) obtained are reacted with polyether blocks (Ba2), in the presence of a catalyst.

The general two-step preparation method for the copolymers of the invention is known and is described, for example, in French patent FR 2 846 332 and in European patent EP 1482 011.

The block formation reaction (Bal) is usually carried out between 180 and 300°C, preferably from 200 to 290°C, the pressure in the reactor is established between 5 and 30 bars, and it is maintained for approximately 2 to 3 hours. The pressure is slowly reduced by bringing the reactor to atmospheric pressure, then the excess water is distilled off, for example, for an hour or two.

The polyamide with carboxylic acid ends having been prepared, the polyether and a catalyst are then added. The polyether can be added one or more times, the same for the catalyst. According to an advantageous form, the polyether is first added, the reaction of the OH ends of the polyether and the COOH ends of the polyamide begins with the formation of ester bonds and elimination of water. As much water as possible is removed from the reaction medium by distillation, then the catalyst is introduced to complete the bonding of the polyamide blocks and the polyether blocks. This second step is carried out with stirring, preferably under a vacuum of at least 15 mm Hg (2000 Pa) at a temperature such that the reagents and the copolymers obtained are in the molten state. For example, this temperature can be between 100 and 400°C and most often 200 and 300°C. The reaction is followed by measuring the torque exerted by the molten polymer on the stirrer or by measuring the electrical power consumed by the stirrer. The end of the reaction is determined by the target torque or power value.

We can also add during the synthesis, at the most appropriate time, one or more molecules used as an antioxidant, for example Irganox® 1010 or Irganox® 245. We can also consider the process for preparing PEBA as that all the monomers are added at the beginning, i.e. in a single step, to carry out the polycondensation: of the lactam(s), or of the amino acid(s), or of the diamine(s) and of the diacid(s) carboxylic; and where appropriate, the other polyamide comonomers;

- in the presence of a chain limiter chosen from dicarboxylic acids;

- in the presence of blocks (Ba2) (polyether);

- in the presence of a catalyst for the reaction between the flexible blocks (Ba2) and the blocks (Bal). Advantageously, said dicarboxylic acid is used as chain limiter, which is introduced in excess relative to the stoichiometry of the diamine(s).

Advantageously, a derivative of a metal chosen from the group formed by titanium, zirconium and hafnium or a strong acid such as phosphoric acid, hypophosphorous acid or boric acid is used as catalyst.

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

Generally speaking, the copolymers with known ether and amide units consist of linear and semi-crystalline aliphatic polyamide sequences (for example “Pebax” from Arkema).

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

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

Concerning the single-material object

It is made up of at least two elements: said at least one first element defined here as (El) and said at least one second element defined here as (E2).

In a first variant, it is made up of the two said elements: E1/E2.

The element El can adhere to the element E2 at least partially, in particular El and E2 adhere at least partially, in particular El and E2 adhere completely, in particular by means of an adhesive. The single-material object is then chosen from those described above.

In a second variant, it is made up of more than two elements: El/(El)n/E2/(E2)m, n and m being between 0 and 5 and when n=0, then m is greater than 0 and when m=0, then n is greater than 0.

It is obvious that when two elements El or two elements E2 are side by side, they can adhere at least partially to one another.

In one embodiment, the homopolyamides or copolyamides of the elements El and E2 comprise an identical monomer, for example amino-ll-undecanoic acid, in particular at least 5% by weight of an identical monomer relative to the sum of the constituents of said homopolyamide or copolyamide, advantageously at least 10%, preferably at least 30%. In one embodiment, the homopolyamides or copolyamides of the elements El and E2 comprise a monomer having an identical C/N ratio, in particular at least 5% by mass of a monomer having an identical C/N relative to the sum of the constituents of said homopolyamide or copolyamide, advantageously 10%, preferably 30%. In a third variant, it can be made up of more than two elements: said at least one first element defined here as (El) and said at least one second element defined here as (E2) and said third element defined here as E3.

In one embodiment, it is made up of three elements: E1/E2/E3 or E1/E3/E2 or E3/E1/E2. The element El can adhere to the element E2 at least partially, in particular El and E2 adhere at least partially, in particular El and E2 adhere completely, in particular by means of an adhesive.

The element E2 can adhere to the element E3 at least partially, in particular E2 and E3 adhere at least partially, in particular E2 and E3 adhere completely, in particular by means of an adhesive. We would not depart from the scope of the invention if at least one other element El and/or E2 and/or E3 were present in said mono-material object.

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

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

In a third variant, the third element, if present, is of non-recycled origin.

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

In a fifth variant, the first element and the third element when present are of non-recycled origin.

In a sixth variant, the second element and the third element when present are of non-recycled origin.

In a seventh variant, the first element, the second element and the third element when present are of non-recycled origin.

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

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

In a tenth variant, the third element, if present, is of at least partially recycled origin.

In an eleventh variant, the first element and the second element are of at least partially recycled origin.

In a twelfth variant, the first element and the third element when present are of at least partially recycled origin.

In a thirteenth variant, the second element and the third element when present are of at least partially recycled origin.

In a fourteenth variant, the first element, the second element and the third element when present are of at least partially recycled origin.

The expression “at least partially recycled” means that there is at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% of recycled composition in said element, said recycled composition itself comprising at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% of long-chain homopolyamide or copolyamide or copolyamide with amide units (Bal) and with polyether patterns (Ba2) of recycled origin.

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

In another embodiment, when the mono-material consists of three or more elements, said composition of the third element (E3) comprises at least one copolyamide with amide units (Bal) and polyether units (Ba2).

In yet another embodiment, when the mono-material consists of three or more elements, said composition of the third element comprises a mixture of at least one homopolyamide or at least one long-chain copolyamide and at least one copolyamide with amide units (Bal) and with polyether units (Ba2).

In another embodiment, the composition of the first element (El) comprises a single homopolyamide or at least one long-chain copolyamide.

In another embodiment, the composition of the second element (E2) comprises a single homopolyamide or at least one long-chain copolyamide.

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

In another embodiment, the composition of the third element (E3) if present comprises a single copolyamide with amide units (Bal) and polyether units (Ba2).

In another embodiment, the composition of the first element (El) comprises a single homopolyamide or at least one long-chain copolyamide and the composition of the second element (E2) comprises a single homopolyamide or at least one long-chain copolyamide. In another embodiment, the composition of the first element (El) comprises a single homopolyamide or at least one long-chain copolyamide and the composition of the second element (E2) comprises a single homopolyamide or at least one long-chain copolyamide and the composition of the third element (E3) if present comprises a single homopolyamide or at least one long-chain copolyamide.

In another embodiment, the composition of the first element (El) comprises a single homopolyamide or at least one long-chain copolyamide and the composition of the second element (E2) comprises a single homopolyamide or at least one long-chain copolyamide and the composition of the third element (E3) if present comprises a single copolyamide with amide units (Bal) and polyether units (Ba2). According to another aspect, the present invention relates to a method of manufacturing a monomaterial object as defined above, comprising the steps consisting of:

Providing a first element consisting of a first composition comprising by weight at least 30%, in particular at least 50%, particularly at least 70%, more particularly at least 90%, relative to the total weight of the first element of at least one homopolyamide or at least one long-chain copolyamide, as defined above,

Providing a second element consisting of a second composition comprising by weight at least 30%, in particular at least 50%, particularly at least 70%, more particularly at least 90%, relative to the total weight of the second element, of at least a homopolyamide or at least one long-chain copolyamide, as defined above,

Assemble the elements of the object using adhesive if necessary, to form the finished or semi-finished object.

In one embodiment, the method defined above comprises an additional step before assembly of supplying a third element consisting of a third composition comprising by weight at least 30%, in particular at least 50%, particularly at least 70%. , more particularly at least 90%, relative to the total weight of the third element of at least one homopolyamide or at least one long-chain copolyamide, as defined above, or at least one copolyamide with amide units (Bal) and patterned polyethers (Ba2) or a mixture of the two. In the case of a semi-finished object, a step of adding other elements not recyclable by the process of the invention but preferably easily separable from the elements of the invention: for example the electronics of a watch , is done.

According to yet another aspect, the present invention relates to a method of recycling an object as defined above, comprising the steps consisting of:

(a) supply of the used item,

(b) optionally separation of the elements of the object which are not recyclable in said process,

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

(d) optionally first grinding of the used object of step (a) or (b), or of step (c) when the cleaning of step (c) is carried out in order to obtain a first ground material ,

(e) optionally washing the first ground material when the cleaning of step (c) is not carried out,

(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 in the case where a first grinding of step (d) has been carried out,

(g) heating the ground material from step (f) until it melts,

(h) optionally compounding and

(i) extrusion or injection of the melt. The first and/or second grinding may or may take place before or after cleaning.

Cleaning is carried out by means of compressed air, in particular under pressure, or by means of hot water or steam from said structure.

Cleaning with compressed air makes it possible to remove non-polymeric particles such as earth, sand or dust from said used object.

Cleaning with hot water or steam makes it possible to solubilize and at least partially remove the water-soluble substances from said used object to obtain the other constituents of said used object.

The temperature of the hot water or the water vapor is between 70°C and 150°C, in particular between 70°C and 120°C.

Hot water can have a pH between 1 and 12.

Compounding step (h) makes it possible to add an impact modifier and/or a filler and/or an additive and/or a plasticizer.

If step (h) is carried out, then the material obtained after said step (h) is in the form of granules to then be extruded or injected.

The expression "used object" designates an object which is no longer new, which has already been used or which has already been used but in no case designates a post-industrial object which would be recycled without having been used or which has not been used. not used. The expression “used object” thus covers in particular an aged object.

In another embodiment, the present invention relates to a recycling process as defined above, further comprising the step of:

(j) Addition of new material to the ground material of the used object before or after step (f) or after step (g). The term new material designates both another polymer, in particular another polyamide, in particular a polyamide with a C/N < 8, as well as fillers and additives.

The mono-material object has at least one dimension (chosen from length, width and thickness), preferably at least two dimensions (chosen from length, width and thickness), or even all three dimensions, greater than 1 mm, preferably greater than 2 mm, advantageously greater than 3 mm. This allows better recyclability, in particular by grinding and/or compounding.

Regarding additives:

The additive is optional and included from 0 to 20%, in particular from 0.1 to 5% by weight.

The additive is chosen from dyes, stabilizers, plasticizers, surfactants, nucleating agents, pigments, brighteners, antioxidants, lubricants, flame retardants, natural waxes, impact modifiers, additives for marking laser, and their mixtures.

Regarding charges: Concerning the fillers, these are reinforcing fibers, which are in particular fibers of mineral, organic or vegetable origin.

Said reinforcing fiber can be sized or unsized.

Said reinforcing fiber can therefore comprise up to 0.1% by weight of a material of organic nature (thermosetting or thermoplastic resin type) called sizing.

Among the fibers of mineral origin, mention may be made of carbon fibers, glass fibers, basalt fibers or basalt-based fibers, silica fibers, or silicon carbide fibers for example. Among the fibers of organic origin, mention may be made of fibers based on thermoplastic or thermosetting polymer, such as semi-aromatic polyamide fibers, aramid fibers or polyolefin fibers for example. Preferably, they are based on an amorphous thermoplastic polymer and have a glass transition temperature Tg greater than the Tg of the polymer or mixture of thermoplastic polymer constituting the pre-impregnation matrix when the latter is amorphous, or greater than the Tf of the polymer or mixture of thermoplastic polymer constituting the pre-impregnation matrix when the latter is semi-crystalline. Among the fibers of plant origin, mention may be made of natural fibers based on flax, hemp, lignin, bamboo, silk in particular spider silk, sisal, and other cellulosic fibers, in particular viscose. These fibers of plant origin can be used pure, treated or coated with a coating layer, in order to facilitate adhesion and impregnation of the thermoplastic polymer matrix.

Preferably said reinforcing fiber is chosen from glass fibers, carbon fibers, basalt fibers and basalt-based fibers.

More advantageously, said reinforcing fiber is chosen from carbon fibers and glass fibers.

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

The glass fibers can be circular or non-circular in section.

A fiber with a circular section is defined as a fiber presenting at any point of its circumference a distance equal to the center of the fiber and therefore represents a perfect or almost perfect circle.

Any fiberglass that does not present this perfect or almost perfect circle is therefore defined as a fiber with a non-circular section.

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

Fiberglass can be:

- either with a circular section with a diameter of between 4 pm and 25 pm, preferably from 4 to 15 pm. - either with a non-circular section with a ratio L/D (L representing the largest dimension of the transverse section of the fiber and D the smallest dimension of the transverse section of said fiber) of 2 to 8, in particular 2 to 4. L and D can be measured by scanning electron microscopy (SEM).

Advantageously, the glass fibers are circular.

The glass fibers are in particular of type E, R, S2, or T. Advantageously the glass fibers are of type E.

In another embodiment, the charges are present from 0 to 65%.

In one embodiment, the fillers are recycled.

For fillers comprising glass, they may in particular be manufactured from industrial production waste or post-consumer glass.

Carbon fibers can for example come from cutting spools of expired long fibers, in particular carbon fibers for aeronautics.

Advantageously, the fillers are chosen from glass fibers, in particular circular, and carbon fibers, in particular glass fibers, in particular circular.

According to another aspect, the present invention relates to a recycled polyamide composition capable of being obtained by the process as defined above.

According to yet another aspect, the present invention relates to a composition comprising by weight: from 30 to 100%, advantageously from 50 to 99% of recycled polyamide from the mono-material objects defined above, from 0 to 70% of virgin polyamides chosen from homopolyamides, in particular long chain, copolyamides, in particular long chain and PEBA, advantageously the virgin polyamide is a homopolyamide, in particular long chain, from 0 to 65% fillers, from 0 to 20% , in particular from 0.1 to 5% of additives, the sum of the constituents being equal to 100%, said recycled polyamide having functions resulting from oxidation reactions chosen from primary amide functions, nitriles, methyl groups at the end of chain, alkenes, formamides, imides, carboxylic acids and alcohols and their mixtures, in a molar ratio relative to the amide functions greater than that of the same polyamide constituting an unused object which has never been used before.

The expression "recycled polyamide from mono-material objects as defined above" is intended to designate a polyamide from a mono-material object which is no longer new, which has already been used or which has already been used but does not in any way designate a polyamide from a post-industrial object which would be recycled without having been used or which has not been used. As opposed to a “virgin” polyamide, a “recycled” polyamide covers in particular an aged polyamide.

When using a mono-material object, new species resulting from oxidation mechanisms, in particular amide functions and/or methylene in alpha of said amide functions, such as imide functions, carboxylic acids, primary amides and alcohols appear in the polyamides constituting said mono-material objects.

Said functions appear due to UV radiation or heat or due to a reaction with a compound with which said object is in contact. For example, gasoline, sunscreen, lubricants...

Said functions can be detected by infrared or NMR spectrometry.

Thus the absorption band from 1700 to 1740 cm-l corresponds to an imide, that from 1680 to 1720 cm-1 to the carbonyl of the carboxylic acid and that from 3580 to 3670 cm-1 corresponds to the alcohol function of the acid carboxylic.

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

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

In a first variant, said composition comprises by weight: from 50 to 70% of recycled polyamide from the mono-material objects defined above, from 30 to 50% of virgin polyamides chosen from homopolyamides, in particular long chain, copolyamides, in particular long chain, and PEBA, advantageously the virgin polyamide is a homopolyamide

0 to 20%, in particular from 0.1 to 5% of additives, the sum of the constituents being equal to 100%.

In a second variant, said composition comprises by weight: from 30 to 50% of recycled polyamide from the mono-material objects defined above, from 0 to 65% of virgin polyamides chosen from homopolyamides, in particular long chain, copolyamides, in particular long chain, and PEBA, advantageously the virgin polyamide is a homopolyamide, in particular long chain, from 5 to 60% fillers,

In a third variant, said composition comprises by weight: from 60 to 80% of recycled polyamide from the mono-material objects defined above, from 0 to 20% of virgin polyamides chosen from homopolyamides, in particular long chain, copolyamides, in particular long chain, and PEBA, advantageously the virgin polyamide is a homopolyamide, in particular long chain, from 20 to 40 % of charges,

0 to 20%, in particular from 0.1 to 5% of additives, the sum of the constituents being equal to 100%. In a fourth variant, said composition comprises by weight: from 40 to 60% of recycled polyamide from the mono-material objects defined above, from 0 to 20% of virgin polyamides chosen from homopolyamides, in particular long chain, copolyamides, in particular long chain, and PEBA, advantageously the virgin polyamide is a homopolyamide, in particular long chain, of 40 to 60% fillers,

0 to 20%, in particular from 0.1 to 5% of additives, the sum of the constituents being equal to 100%. In one embodiment, in said compositions of this other aspect and its four variants, the term “includes” is replaced by the term “consisting of”.

The compositions of these four variants and their embodiments are compositions in particular adapted to the embodiment in which the mono-material object defined above is characterized in that only one of the two compositions comprises a filler, the other being deprived of it.

Recycled polyamide presents particularities, and in particular new species resulting from oxidation mechanisms, when it comes from objects as defined above.

The expression "new species resulting from oxidation mechanisms" is intended to designate, within the meaning of the invention, the primary amide functions, nitriles, methyl groups at the end of the chain, alkenes, formamides, imides, acids carboxylic acids and alcohols which may appear in the recycled polyamide of the invention.

The recycled polyamide of the invention has functions resulting from oxidation reactions chosen from primary amide functions, nitriles, methyl groups at the end of the chain, alkenes, formamides, imides, carboxylic acids and alcohols.

According to a preferred embodiment of the invention, the recycled polyamide of the invention has functions resulting from oxidation reactions chosen from nitriles and methyl groups at the end of the chain.

According to a preferred embodiment of the invention, the recycled polyamide of the invention has functions resulting from oxidation reactions chosen from nitriles and methyl groups at the end of the chain in a molar ratio relative to the higher secondary amide functions to that of same virgin polyamide, and primary amine functions in a molar ratio relative to secondary amide functions lower than that of the same virgin polyamide.

These functions can be identified and quantified using infrared spectroscopy and/or proton or carbon NMR.

NMR measurements can be carried out in the HFIP/CD2CI2 mixture. For example, 20 mg of polymer can be dissolved in 0.7 mL of solvent with an HFIP/CD2CI2 ratio of 1/3. The dichloromethane (CD2CI2)/trifluoroacetic anhydride (ATFA) mixture can also be used.

This method is described in the doctoral thesis of E. Goncalves in chapter 11.2.3 published in 2011, incorporated by reference. Analyzes in these two solvents make it possible to identify a majority of functions formed during the life of the polyamide.

Thus, for example, in infrared spectroscopy, the absorption band from 1700 to 1740 cm-l corresponds to an imide, that from 1680 to 1720 cm-1 to the carbonyl of the carboxylic acid and that from 3580 to 3670 cm -1 corresponds to the alcohol function of the carboxylic acid.

The absorption bands of 1180 and 1723 cm-1 correspond to formates. The bands at 900 and 1660 cm-1 correspond to alkenes.

For example, the degradation of polyethers included in polyamide elastomers, in particular PEBA, can be quantified by infrared spectroscopy by comparing the ratio between the intensities of the band 1111 cm-1 (vibration of the C-0 bond of the ether group) or at 2791 cm-1 (CH2 in position a of the ether function) and the band at 1725 cm-1 (carbonyl function).

Quantification by NMR is, for example, carried out by comparing the intensity of the lines of functions not present in the virgin polymer to the lines corresponding to CH2 in a of amide, ether or other CH2 functions in the context of proton NMR. . In carbon NMR, the intensity of the functional lines formed during the life of the polymer is compared to the intensity of the carbon lines of amides or CH2.

Some of the functions mentioned above can for example be observed by 13C NMR in the solvent HFIP/CD2CI2. Thus the line at 36 ppm corresponds to CH2 at a of the primary amide, that at 34 ppm corresponds to CH2 at a of the carboxylic acid. These species can be quantified by integrating the area under the lines and comparing them to the area under the line 37.1 ppm corresponding to the secondary amide. Similarly, the lines corresponding to the carbonyl groups of the primary amide, carboxylic acid and secondary amide functions are observed at 181.2 ppm, 179.6 ppm and 177.4 ppm respectively. The line at 16.7 ppm corresponds to CH2 in a of the nitrile group. The formamide group gives a chemical shift at 163.0 ppm and 166.3 ppm.

Other functions mentioned above can be observed in proton NMR (1H NMR) in the solvent HFIP/CD2CI2 as described above. The line of the CHO groups of the formamides comes out at 7.92 and 8.01 ppm. The line corresponding to CH2 in a of primary amides can be observed at 2.30 ppm. The line at 0.9 ppm corresponds to CH3 groups of the CH3-(CH2)n type. The line at 2.40 ppm corresponds to CH2 in a of the nitrile function. The line corresponding to the proton of the formate function is observed at 8.1 ppm. The line corresponding to the proton of the aldehyde function is observed at 9.7 ppm. Similar to what is described for carbon NMR, the ratios of new functions relative to secondary amides can be determined by integrating the area under the lines and comparing them to the area under the line corresponding to CH2 in to the secondary amide (2.20 ppm) or to the area under the line corresponding to the CONH proton of the secondary amide (6.0 - 6.1 PPm).

According to any one of the embodiments of the invention, in a recycled polyamide of the invention, the molar ratio of the functions resulting from oxidation reactions relative to the secondary amide functions is between 0.0005 and 0.3 .

According to any one of the embodiments of the invention, in a recycled polyamide of the invention, the molar ratio of the imide functions relative to the secondary amide functions is between 0.0005 and 0.1, in particular between 0.001 and 0.08, especially between 0.005 and 0.05. According to any one of the embodiments of the invention, in a recycled polyamide of the invention, the molar ratio of the carboxylic acid functions relative to the secondary amide functions is between 0.0005 and 0.1, in particular between 0.001 and 0.08, especially between 0.005 and 0.05.

According to any one of the embodiments of the invention, in a recycled polyamide of the invention, the molar ratio of the alcohol functions relative to the secondary amide functions is between 0.0005 and 0.1, in particular between 0.001 and 0.08, especially between 0.005 and 0.05. According to any one of the embodiments of the invention, in a recycled polyamide of the invention, the molar ratio of the primary amide functions relative to the secondary amide functions is between 0.0005 and 0.1, in particular between 0.001 and 0.08, especially between 0.005 and 0.05.

According to any one of the embodiments of the invention, in a recycled polyamide of the invention, the molar ratio of the nitrile functions relative to the secondary amide functions is between 0.0005 and 0.1, in particular between 0.001 and 0.08, especially between 0.005 and 0.05. According to any one of the embodiments of the invention, in a recycled polyamide of the invention, the molar ratio of the alkene functions relative to the secondary amide functions is between 0.0005 and 0.1, in particular between 0.001 and 0.08, especially between 0.005 and 0.05. According to any one of the embodiments of the invention, in a recycled polyamide of the invention, the molar ratio of the formamide functions relative to the secondary amide functions is between 0.0005 and 0.1, in particular between 0.001 and 0.08, especially between 0.005 and 0.05. According to any one of the embodiments of the invention, in a recycled polyamide of the invention, the molar ratio of the methyl functions at the end of the chain relative to the secondary amide functions is between 0.0005 and 0.2, notably between 0.001 and 0.08, in particular between 0.005 and 0.05.

It is obvious that depending on the waste and the exposure to which it has been subjected, one or more functions resulting from oxidation reactions may be present.

In one embodiment, said molar ratio of the functions resulting from oxidation reactions relative to the secondary amide functions is comprised from 1/10,000 to 1/20.

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

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

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

In a third variant, said molar ratio of alcohol functions is between 1/1000 and 1/20 and advantageously between 1/1000 and 1/25, very advantageously between 1/200 and 1/50.

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

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

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

It is obvious that depending on the used mono-material objects and the exposure to which they have been subjected, one or more functions resulting from oxidation reactions may be present. The composition also advantageously comprises stabilizer residues chosen from phenols, quinones, stylbenequinones and phosphite.

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

According to another aspect, the present invention relates to the use of a composition as defined above for the manufacture of objects, in particular mono-materials.

Said mono-material object thus manufactured from a used mono-material object can itself be recycled according to the process of the invention at least once, in particular from 1 to 10 times.

Brief description of the figure:

Figure 1 shows the CH2CO areas of the different secondary amide, primary amide and carboxylic acid functions in C13 NMR in a solvent mixture with an HFIP/CD2CI2 ratio of 1/3. Top spectrum: PA 11 from sunglasses worn for five years in a sunny environment and bottom spectrum: PA 11 based on 100% virgin material.

EXAMPLES

The EC1 and Eli phone cases were assembled using polyamide adhesive. Element 3 is between elements 1 and 2. The percentages indicated are mass percentages.

PA 11: homopolyamide 11 having 45 peq/g of end of NH2 chain and 40 peq/g of end of COOH chain. The inherent viscosity of this polyamide is 1.46.

PA 12: homopolyamide 12 having 25 peq/g of end of NH2 chain and 65 peq/g of end of COOH chain. The inherent viscosity of this polyamide is 1.21.

PA 6: homopolyamide 6 having 24 peq/g of end of NH2 chain and 65 peq/g of end of COOH chain. The inherent viscosity of this polyamide is 1.42.

The injected part 3 consists of 50% PA 6 and 50% PA 11. The inherent viscosity of this composition is 1.35.

The EC3 phone case does not have good mechanical properties (shock at - 30 °C according to ISO 179 leA less than 8 kJ/m ² ) and has therefore not been recycled.

The injected part 4 is made up of 90% PA 11, 4% PA 610 and 6% PA 6. The inherent viscosity of this polyamide is 1.55.

The inherent viscosities are determined in m-cresol according to the ISO 307:2007 standard but by changing the solvent (use of m-cresol instead of sulfuric acid and the temperature being 20°C)

The objects ECI, EC3, EI3 and El 1 were crushed into ground material having a size less than 30 mm then compounded in an 18 mm twin-screw extruder at a flow rate of 5 kg/h and a temperature of 280 ° C in order to obtain granules to evaluate the properties obtained during the second life of the material. The granules thus obtained are then injected using a Battenfeld BA800 CDC press to manufacture ISO 527 IA test pieces and ISO 179 impact bars. The following parameters were applied during the injection:

- Sheath temperature: 270°C.

- Nozzle temperature: 290°C.

- Mold temperature: 40°C.

- Cycle time: 60 seconds.

The impact resistance was determined according to ISO 179-1: 2010 / leA (Charpy impact) on 5 bars measuring 80mm x 10mm x 4mm, V-notched, at a temperature of -30°C +/-2°C under a relative humidity of 50% +/- 10% on dry samples.

The water recovery measurements were carried out according to the following protocol on ISO 527 IA test pieces:

Drying of the test pieces at 80°C and 1 mbar for 16 hours

Weighing of test pieces (m to tO) Conditioned for 7 days at 70°C and 62% relative humidity

Weighing of test pieces after conditioning (mcondi)

The examples above show that the properties obtained after recycling of the object according to the invention are better and therefore that it can be recycled to manufacture new high-performance objects.

Water recovery measurements carried out on ISO 527 IA test pieces show that the compositions obtained after recycling the objects will have better dimensional stability (lower water absorption). In addition, the evaluation of cold shock resistance shows that the objects of the invention have better properties after recycling.

Examples EC2 and El 2 are electronic watch parts. The watch glass is clipped to the case without adhesive. Non-polymeric elements of the watch having been removed beforehand (such as electronics).

PA 11/B10: statistical copolyamide 11/B10 having a molar ratio 0.25/2. The inherent viscosity of this polyamide is 1.15.

The EC2 and EI2 objects were crushed into ground material having a size less than 30 mm then compounded in an 18 mm twin-screw extruder at a flow rate of 5 kg/h and a temperature of 300 ° C in order to obtain granules to evaluate the properties obtained during the second life of the material.

The granules thus obtained are then injected using a Battenfeld BA800 CDC press to manufacture ISO 179 impact bars. The following parameters were applied during the injection: - Sheath temperature: 300°C.

- Nozzle temperature: 320°C.

- Mold temperature: 60°C.

- Cycle time: 40 seconds. The impact resistance was determined according to ISO 179-1: 2010 / leA (Charpy impact) on 5 bars measuring 80mm x 10mm x 4mm, V-notched, at a temperature of -30°C +/-2°C under a relative humidity of 50% +/- 10% on dry samples.

The evaluation of cold impact resistance shows that the objects of the invention have better properties after recycling.

Claims

CLAIMS Mono-material object comprising at least two elements:

- at least one first element consisting of a first composition comprising by weight at least 30%, in particular at least 50%, particularly at least 70%, more particularly at least 90%, relative to the total weight of the first element, at least one homopolyamide or at least one long-chain copolyamide, said at least one homopolyamide and said at least one copolyamide independently representing a repeating unit chosen from a unit obtained from the polycondensation of at least one C4-C36 amino acid, a unit obtained from the polycondensation of at least one C ₄ -C ₃ 6 lactam and an XY unit obtained from the polycondensation: of at least one diamine, said diamine being chosen among a linear or branched aliphatic diamine, a cycloaliphatic diamine and a semi-arylaliphatic diamine or a mixture thereof, and at least one dicarboxylic acid, said diacid being chosen from: an aliphatic diacid, a cycloaliphatic diacid and a diacid aromatic or a mixture thereof, said diamine and said diacid comprising from 4 to 36 carbon atoms, advantageously from 6 to 18 carbon atoms, a copolyamide with amide units (Bal) and polyether units (Ba2) being excluded from said first composition,

- at least one second element consisting of a second composition comprising by weight at least 30%, in particular at least 50%, particularly at least 70%, more particularly at least 90%, relative to the total weight of the second element, at least one homopolyamide or at least one long-chain copolyamide, said at least one homopolyamide and said at least one copolyamide being as defined above for the first composition, a copolyamide with amide units (Bal) and with polyether units (Ba2) being excluded from said second composition, said first and second elements being able to adhere at least partially to each other, said at least one homopolyamide or at least one copolyamide, preferably said at least one homopolyamide or at least one majority copolyamide, of the first composition and/or said at least one homopolyamide or at least one copolyamide, of preferably said at least one homopolyamide or at least one majority copolyamide, of the second composition having a C/N ratio greater than or equal to 8, in particular greater than or equal to 9, in particular greater than or equal to 10, said object being exclusion of a single-layer or multi-layer structure for the transport, distribution or storage of a fluid.

2. Mono-material object according to claim 1, characterized in that it is chosen from an electronic article, a textile article, an optical article, a household appliance article, a cosmetic article, a sporting article, a stationery article, an item of luggage, a toy, furniture and automobile parts.

3. Single-material object according to claim 1 or 2, characterized in that the first and the second composition are different.

4. Mono-material object according to claim 3, characterized in that only one of the two compositions comprises a filler, the other being devoid of it.

5. Mono-material object according to claim 1 to 4, characterized in that the first composition and the second composition comprise the same polyamide, in particular a PAU.

6. Mono-material object according to claim 1 to 4, characterized in that at least 10% by weight of the patterns, in particular at least 30% by weight, constituting said at least one homopolyamide or said at least one copolyamide of the first composition and the second composition are identical, in particular said patterns are PAU patterns.

7. Mono-material object according to one of claims 1 to 6, characterized in that said first and second element are chosen from the following constituents: a textile, a film or textured film, a foam, an injected part, a part extruded, a 3D printed part, an adhesive, a non-woven, a veil and a consolidated thermoplastic composite part.

8. Single-material object according to claim 7, characterized in that it comprises at least two constituents defined in claim 7 and which are different.

9. Mono-material object according to claim 7, characterized in that it comprises at least at least three constituents defined in claim 7, in particular different. Mono-material object according to one of claims 1 to 9, characterized in that the first and the second element adhere to each other by bonding by means of a non-polyamide adhesive with a content of 0.01 % to 10% by weight, in particular from 0.1% to 4% by weight relative to the total mass of the object. Mono-material object according to one of claims 1 to 10, characterized in that it comprises at least one third element consisting of a third composition comprising at least one homopolyamide or at least one long-chain copolyamide or at least one copolyamide with amide units (Bal) and with polyether units (Ba2) or a mixture thereof, said at least one homopolyamide or at least one long-chain copolyamide being as defined in claim 1. Process for manufacturing an object mono-material according to one of claims 1 to 11, comprising the steps consisting of:

Providing a first element consisting of a first composition comprising by weight at least 30%, in particular at least 50%, particularly at least 70%, more particularly at least 90%, relative to the total weight of the first element of at least one homopolyamide or at least one long-chain copolyamide, as defined in claim 1,

Providing a second element consisting of a second composition comprising by weight at least 30%, in particular at least 50%, particularly at least 70%, more particularly at least 90%, relative to the total weight of the second element, of at least a homopolyamide or at least one long-chain copolyamide, as defined in claim 1,

Assemble the elements of the object using adhesive if necessary, to form the finished or semi-finished object. Process for recycling the object as defined in one of claims 1 to 12, comprising the steps consisting of:

(a) supply of the used item,

(c) optionally cleaning the used object from step (a) or (b), (d) optionally first grinding of the used object of step (a) or (b), or of step (c) when the cleaning of step (c) is carried out in order to obtain a first ground material ,

(g) heating the ground material from step (f) until it melts,

(h) optionally compounding and

(i) extrusion or injection of the melt. Recycling method according to claim 13, further comprising the step of:

(j) Addition of new material to the ground material of the used object before or after step (f) or after step (g). Composition of recycled polyamide capable of being obtained by the process according to claims 13 to 14. Composition comprising by weight: from 30 to 100%, advantageously from 50 to 99% of recycled polyamide from the objects defined in one of claims 1 to 11, from 0 to 70% of virgin polyamides chosen from homopolyamides, in particular long chain, copolyamides, in particular long chain and PEBA, advantageously the virgin polyamide is a homopolyamide, in particular long chain, of 0 at 65% load

0 to 20%, in particular from 0.1 to 5% of additives, the sum of the constituents being equal to 100%, said recycled polyamide having functions resulting from oxidation reactions chosen from primary amide functions, nitriles, groups methyl at the end of the chain, alkenes, formamides, imides, carboxylic acids and alcohols and their mixtures, in a molar ratio relative to the amide functions greater than that of the same polyamide constituting an unused object which has never been used before.

17. Composition according to claim 16, characterized in that said molar ratio of the functions resulting from oxidation reactions relative to the secondary amide functions is comprised from 1/10,000 to 1/20.

18. Composition according to one of claims 16 to 17, characterized in that said molar ratio of the imide functions relative to the secondary amide functions is comprised from 1/1000 to 1/20, in particular from 1/500 to 1/20, in particular from 1/200 to 1/50.

19. Composition according to one of claims 16 to 18, characterized in that said molar ratio of the carboxylic acid functions relative to the secondary amide functions is comprised from 1/5000 to 1/20, in particular from 1/3000 to 1/50 very advantageously ranging from 1/500 to 1/15.

20. Composition according to one of claims 16 to 19, characterized in that said molar ratio of alcohol functions relative to secondary amide functions is from 1/1000 to 1/20 and advantageously from 1/1000 to 1/25 very advantageously ranging from 1/200 to 1/50.

21. Composition according to one of claims 16 to 20, characterized in that said molar ratio of primary amide functions relative to secondary amide functions is from 1/2000 to 1/20 and advantageously from 1/1000 to 1/ 100 very advantageously included from 1/1000 to 1/500.

22. Composition according to one of claims 16 to 21, characterized in that said molar ratio of nitrile functions relative to secondary amide functions is from 1/1000 to 1/20 and advantageously from 1/500 to 1/15 very advantageously ranging from 1/100 to 1/10.

23. Composition according to one of claims 16 to 22, characterized in that said molar ratio of the methyl functions at the end of the chain relative to the secondary amide functions is between 1/5000 and 1/50 and advantageously between 1/2000 at 1/100 very advantageously included from 1/1000 to 1/200.

24. Use of the composition according to one of claims 15 to 23 for the manufacture of objects, in particular mono-materials.