Sports shoe with improved recyclability

Abstract

The present invention relates generally to single material footwear consisting of: (i) 15% to 65% by weight of a thermoplastic polymer selected from polyamides or copolyamides; (ii) from 35% to 85% by weight of a PEBA thermoplastic elastomer; and (iii) from 0 to 15% by weight of an additive. The invention also relates to a method for its manufacture and for its recycling, and also to a composition obtainable after recycling and its use for the manufacture of footwear.

Description

Technical Field

[0001] The present patent application relates to articles of footwear having improved recyclability, a process for their manufacture and a process for their recycling, as well as compositions obtained thereby and their use in the manufacture of articles of footwear. Background Art

[0002] Through a circular economy, waste generation, depletion of the earth's resources and environmental impact can be limited. There is currently a particular interest in producing objects with the aid of 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 street furniture or roads.

[0003] In the context of sustainable consumption and production patterns, the recyclability of frequently renewed items, such as sports equipment, and the quality of the resulting recycled products are of particular importance. However, the performance requirements for these items are particularly high.

[0004] Patent EP 3 081 109 B1 proposes an article of sports footwear, the upper and the sole of which are made mainly or even completely of the same thermoplastic base material in order to facilitate their recycling. However, difficulties still appear to exist, since the recycled product thus obtained has limitations in terms of performance, since the density of the parts of the article of footwear differs according to their respective functions.

[0005] Patent application WO 2020 / 201370 A1 proposes a method for recycling such articles of footwear, in which the articles are ground and then melted. Like the previous document, this document focuses on TPU.

[0006] It is important that the products employed are stable enough to be recycled completely safely. However, when recycling TPU, the formation of dangerous compounds isocyanates can be observed.

[0007] Furthermore, the proposed articles of footwear do not always make available recycled compositions having properties sufficient to allow their use as performance polymers. Summary of the invention

[0008] The object of the present invention is therefore to propose a mono-material article of footwear, the composition of which is studied so as to make it possible to obtain, upon recycling, a composition capable of being used in applications requiring high performance.

[0009] It has now been demonstrated that the unique combination of a polyamide portion and a polyether (PEBA) portion with amide blocks in a mono-material article of footwear (excluding additives) allows better retention of properties during recycling.

[0010] In fact, the presence of polyamide in the composition particularly favours the ageing resistance and therefore the lifetime of the object and its recycling process. For its part, the presence of the more flexible PEBA contributes to improving the mechanical strength of the object throughout its lifetime, both before and after recycling.

[0011] Thus, according to a first aspect, a subject of the invention is a mono-material article of footwear consisting of:

[0012] (i) 15 to 65% by weight of one or more thermoplastic polymers selected from polyamides and copolyamides;

[0013] (ii) 35 to 85% by weight of one or more thermoplastic elastomers selected from PEBA; and

[0014] (iii) 0 to 15 wt % of additives.

[0015] According to a preferred embodiment, the footwear article consists of:

[0016] (i) 25 to 55% by weight of one or more thermoplastic polymers selected from polyamides or copolyamides;

[0017] (ii) 45 to 75% by weight of one or more thermoplastic elastomers selected from PEBA; and

[0018] (iii) 0 to 15 wt % of additives.

[0019] According to one embodiment, component (i) comprises a polyamide or copolyamide selected from the group consisting of PA 612, PA 613, PA 912, PA 1010, PA 1012, PA 6, PA 11, PA 12, PA 6 / 11, PA 6 / 12, PA 11 / 12, PA 6 / 11 / 12, PA 6 / 66 / 12, PA 6 / 1010, PA 6 / 1012, PA 6 / 1010 / 1012, PA 6 / 1012 / 12, PA 6 / 66 / 11 / 12 and PA 6 / 1010 / 1012 / 1014, alone or as a mixture.

[0020] According to one embodiment, component (ii) comprises a PEBA selected from the group consisting of PA 6 / 11 blocks and blocks derived from PTMG, PA 6 / 12 blocks and blocks derived from PTMG, PA 11 / 12 blocks and blocks derived from PTMG, PA 6 / 11 / 12 blocks and blocks derived from PTMG, PA 6 / 66 / 12 blocks and blocks derived from PTMG, PA 6 / 1010 blocks and blocks derived from PTMG, PA 6 / 1012 blocks and blocks derived from PTMG, PA 6 / 1010 / 1012 blocks and blocks derived from PTMG, PA 6 / 1012 / 12 blocks and blocks derived from PTMG, PA 6 blocks and blocks derived from PTMG, PA 11 blocks and blocks derived from PTMG, PA 12 blocks and blocks derived from PTMG, PA 6 blocks and blocks derived from PEG, PA 11 blocks and blocks derived from PEG, and PA 12 blocks and blocks derived from PEG.

[0021] According to one embodiment, the polyamide or copolyamide of component (i) has an average ratio of the number of carbon atoms per amide function of greater than 6, preferably greater than 8 and in particular 10 or more.

[0022] According to one embodiment, the mono-material article of footwear contains as an additive 0 to 10% by weight, preferably 0.1 to 4% by weight, of a binder.

[0023] According to one embodiment, the adhesive contains or consists of polyurethane.

[0024] According to a second aspect, the invention relates to a method for manufacturing such a single-material article of footwear, comprising the following steps:

[0025] I. Providing a material comprising one or more polyamides or copolyamides, one or more PEBAs and / or one or more additives suitable for use in the various components of the article of footwear;

[0026] II. manufacturing components of the article of footwear from corresponding thermoplastic materials; and

[0027] III. assembling the components of the article of footwear, where appropriate with the aid of an adhesive, to form a finished article of footwear,

[0028] The materials used are selected so that the finished footwear article contains 15 to 65% by weight of one or more thermoplastic polymers chosen from polyamides and copolyamides; 35 to 85% by weight of one or more thermoplastic elastomers chosen from PEBA; and 0 to 15% by weight of additives.

[0029] According to one embodiment, the materials used are selected so that the finished article of footwear comprises 25 to 55% by weight of one or more thermoplastic polymers chosen from polyamides and copolyamides; 45 to 75% by weight of one or more thermoplastic elastomers chosen from PEBA; and 0 to 15% by weight of additives.

[0030] According to a third aspect, the invention relates to a method for recycling such a mono-material article of footwear, comprising the following steps:

[0031] (a) supplying used footwear;

[0032] (b) grinding the cleaned article of footwear to obtain a ground material;

[0033] (c) heating the ground material until it melts; and

[0034] (d) Extruding the melt into pellets.

[0035] According to one embodiment, it further comprises the following steps:

[0036] (e) adding new material to the ground used article of footwear either before or after step (d).

[0037] According to a fourth aspect, the present invention relates to a recycled polymer composition obtainable by said recycling process.

[0038] According to a fifth aspect, the present invention relates to a composition consisting of:

[0039] (a) 20 to 100% by weight, advantageously 30 to 99% by weight, even more preferably 50 to 98% by weight, of a granulated, ground, mono-material article of footwear consisting of:

[0040] a. 15 to 65% by weight, in particular 25 to 55% by weight, of one or more thermoplastic polymers selected from polyamides or copolyamides;

[0041] b. 35 to 85% by weight, in particular 45 to 75% by weight, of one or more thermoplastic elastomers chosen from PEBA; and

[0042] c. 0% to 15% additives;

[0043] (b) 0 to 80% by weight, preferably 1 to 70% by weight and in particular 2 to 50% by weight of a virgin polymer chosen from polyamides, copolyamides and PEBAs; and

[0044] (c) 0 to 50% by weight of additives.

[0045] According to a last aspect, the present invention relates to the use of said composition produced by the recycling process for the manufacture of articles of footwear, in particular mono-material articles of footwear. DETAILED DESCRIPTION

[0046] Definition of terms

[0047] The term "polymer blend" is intended to mean a macroscopically homogeneous polymer composition. The term also encompasses such compositions consisting of mutually immiscible phases dispersed on the micrometer scale.

[0048] The term "copolymer" is understood to mean a polymer obtained by copolymerization of at least two chemically different types of monomers (referred to as comonomers). Therefore, a copolymer is formed by at least two repeating units. It can also be formed by three or more repeating units. More specifically, the term "sequential copolymer" or "block copolymer" is understood to mean a copolymer in the above sense in which at least two different monomer blocks are connected by covalent bonding. The length of the block can be variable. Preferably, the block is composed of 1 to 1000, preferably 1 to 100, and particularly 1 to 50 repeating units, respectively. The connection between two monomer blocks may sometimes require an intermediate non-repeating unit referred to as a connecting block.

[0049] The term "monomer" in the context of polyamides is to be understood as meaning "repeating unit". In practice, the case in which the repeating units of the polyamide consist of a combination of a diacid and a diamine is a special case. It is believed that it is the combination of a diamine and a diacid, that is to say a diamine.diacid pair (in equimolar amounts), which corresponds to a monomer. The underlying reason for this is that a diacid or a diamine alone is only a structural unit and cannot be polymerized on its own.

[0050] The term "monomaterial footwear" is understood to mean an article of footwear that is essentially made of polymers of a given family. In the broad definition of the invention, these are thermoplastic polymers selected from polyamides and their copolymers and polyethers with amide blocks (PEBA). In principle, a monomaterial article of footwear will not contain other polymers, whether thermosetting polymers or polymers belonging to other thermoplastic polymer families. On the other hand, it may contain small amounts of agents called additives in the formulation of the thermoplastic polymers used for the various parts of the article or for specific parts of the article. The example mentioned is the presence of an adhesive in the monomaterial article of footwear for its assembly purposes. Advantageously, this is a thermoplastic adhesive, and in particular an adhesive in the form of a polyamide or copolyamide. However, a non-thermoplastic adhesive, such as a polyurethane adhesive, may also be provided when the presence of the non-thermoplastic adhesive does not exceed 10% by weight and preferably 4% by weight relative to the total weight of the article of footwear.

[0051] The term "intrinsic viscosity" is understood to mean the viscosity measured according to the following steps:

[0052] - taking a polymer sample of between 0.07 and 0.10 g and preferably a maximum of 0.15 g,

[0053] - add by weighing sufficient amount of m-cresol solvent to obtain a concentration (C) of 0.5 g / L,

[0054] - Heat the mixture on a hot plate adjusted to 100°C ± 5°C with stirring until the polymer has completely dissolved,

[0055] - cooling the solution to ambient temperature, preferably for at least 30 minutes,

[0056] - Measure the flow time t0 of the pure solvent and the flow time t of the solution using a micro-Ubbelohde viscometer in a thermostatically controlled bath adjusted to 20°C ± 0.05°C,

[0057] - Viscosity is calculated according to the formula 1 / C x Ln(t / t0), where C represents concentration and Ln represents natural logarithm.

[0058] For each sample, three measurements were performed on different solutions and the average value was calculated.

[0059] The term "thermoplastic polymer" is understood to mean a polymer which has the property of softening when heated sufficiently and hardening again when cooled.

[0060] The term "semicrystalline polyamide" is understood to mean a polyamide having a melting temperature (Tm) in DSC according to Standard ISO 11357-3:2013 and a crystallization enthalpy measured in DSC during a cooling step at a rate of 20 K / min according to Standard ISO 11357-3, 2013 of greater than 20 J / g, preferably greater than 30 J / g.

[0061] The term “enthalpy of fusion” is understood to mean the amount of heat consumed during the solid / liquid transition of a thermoplastic elastomer measured by differential scanning calorimetry according to Standard ISO 11257-3:1999.

[0062] The nomenclature used to designate the polyamides according to the invention follows standard ISO 1874-1:2010.

[0063] In the following, hardness is measured according to standard ISO 868:2003.

[0064] Single material footwear

[0065] In its broadest definition, the invention relates in particular to a mono-material article of footwear comprising parts consisting essentially of polymers of the polyamide, copolyamide and PEBA series (that is to say without additives). In addition to these parts, the mono-material article of footwear may comprise a small proportion (less than 12% by weight, preferably less than 10% by weight and more preferably less than 5% by weight relative to the weight of the finished mono-material article of footwear) of functional or decorative elements consisting of a different material. Advantageously, the mono-material article of footwear consists essentially of a polymer derived from this series.

[0066] According to one aspect, the invention relates to a single-material article of footwear consisting of:

[0067] (i) 15 to 65% by weight of one or more thermoplastic polymers selected from polyamides and copolyamides;

[0068] (ii) 35 to 85% by weight of one or more thermoplastic elastomers selected from PEBA; and

[0069] (iii) 0 to 15 wt % of additives.

[0070] Polyamide and copolyamide

[0071] As mentioned above, the mono-material article of footwear according to the invention comprises one or more polyamides or copolyamides.

[0072] In the context of this specification, the term "copolyamide" is understood to mean a polymer derived from the polymerization of several monomers linked by amide functional groups. However, copolymers comprising polyether blocks, such as PEBA, are excluded from this definition.

[0073] According to one embodiment, the polyamide is derived from the condensation of one or more monomers of the α,ω-aminocarboxylic acid type or one or more monomers of the lactam type (“Z” type).

[0074] As examples of α,ω-aminocarboxylic acids, mention may be made of α,ω-amino acids such as aminocaproic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid, n-heptyl-11-aminoundecanoic acid and 12-aminododecanoic acid.

[0075] As examples of lactams, mention may be made of those having 3 to 12 carbon atoms in the main ring and which may be substituted. Mention may be made, for example, of β,β-dimethylpropiolactam, α,α-dimethylpropiolactam, valerolactam, caprolactam, capryllactam, enantholactam, 2-pyrrolidone and lauryl lactam.

[0076] Semi-crystalline polyamides will most often be used to make mono-material footwear articles. Advantageously, these are aliphatic polyamides. Particularly preferred are polyamides in which the average number of carbon atoms per amide function is greater than 6, preferably greater than 8 and most particularly 10 or more. Advantageously, they are polyamides without cyclic structures, whether aromatic or cycloaliphatic.

[0077] Examples of preferred polyamides of this type include PA 6, PA 11 and PA 12 and mixtures of these.

[0078] According to one embodiment, the polyamide is derived from the condensation of a dicarboxylic acid with an aliphatic, cycloaliphatic or aromatic diamine (“XY” type, X representing the number of carbon atoms of the diamine and Y representing the number of carbon atoms of the dicarboxylic acid).

[0079] Examples of diamines include aliphatic diamines having 4 to 16 and preferably 6 to 12 carbon atoms, the diamine X also being aromatic or cycloaliphatic. Mention may be made, by way of example, of hexamethylenediamine, piperazine, tetramethylenediamine, octamethylenediamine, decamethylenediamine, dodecamethylenediamine, 1,5-diaminohexane, 2,2,4-trimethyl-1,6-diaminohexane, polyol diamines, isophoronediamine (IPD), methylpentamethylenediamine (MPMD), bis(aminocyclohexyl)methane (BACM), bis(3-methyl-4-aminocyclohexyl)methane (BMACM), meta-xylylenediamine, trimethylhexamethylenediamine.

[0080] Examples of dicarboxylic acids include acids Y having between 4 and 18 carbon atoms, preferably 9 to 12 carbon atoms. Mention may be made, for example, of succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, isophthalic acid, 1,4-cyclohexanedicarboxylic acid, terephthalic acid, the sodium or lithium salts of sulfoisophthalic acid, dimerized fatty acids (especially those having a dimer content of at least 98% and / or being hydrogenated) and 1,2-dodecanedioic acid HOOC-(CH 2 ) 10 -COOH.

[0081] Examples of preferred polyamides of this type include PA 516 resulting from the condensation of pentamethylenediamine with hexadecanedioic acid, PA 612 resulting from the condensation of hexamethylenediamine with 1,12-dodecanedioc acid; PA 613 resulting from the condensation of hexamethylenediamine with brassylic acid; PA 912 resulting from the condensation of 1,9-nonanediamine with 1,12-dodecanedioc acid; PA 129 resulting from the condensation of 1,12-dodecanediamine with azelaic acid; PA 1010 resulting from the condensation of 1,10-decanediamine with sebacic acid; and PA 1012 resulting from the condensation of 1,10-decanediamine with 1,12-dodecanedioc acid.

[0082] According to one embodiment, the polyamide is a copolyamide resulting from the polycondensation of:

[0083] - at least two different monomers selected from different α,ω-aminocarboxylic acids or from two different lactams or from a lactam and an α,ω-aminocarboxylic acid having different carbon numbers; or

[0084] - at least one α,ω-aminocarboxylic acid (or lactam), at least one diamine and at least one dicarboxylic acid, or

[0085] - an aliphatic diamine and an aliphatic dicarboxylic acid and at least one other monomer selected from aliphatic diamines other than the aforementioned aliphatic diamines and aliphatic diacids other than the aforementioned aliphatic diacids.

[0086] The notations PAZ / XY, PAZ / Z', PAZ / XY / X'Y', PAZ / Z' / XY, PAZ / Z' / XY / X'Y' etc. relate to copolyamides wherein XY, Z, X'Y', Z' etc. represent XY or Z homopolyamide monomers as described above, X'Y' being the same as or different from XY and Z' being the same as or different from Z.

[0087] According to one embodiment, one of the monomers constituting the copolyamide may account for more than 50 mass %, preferably more than 60 mass % of the total monomer mixture. According to one embodiment, one of the monomers constituting the copolyamide may account for less than 90 mass %, preferably less than 80 mass % of the total monomer mixture.

[0088] Examples of particularly preferred copolyamides are blocks of PA 6 / 11, PA 6 / 12, PA 11 / 12, PA 6 / 11 / 12, PA 6 / 66 / 12, PA 6 / 1010, PA 6 / 1012, PA 6 / 1010 / 1012, PA 6 / 1012 / 12, PA 6 / 66 / 11 / 12 and PA 6 / 1010 / 1012 / 1014, and mixtures thereof.

[0089] It is also possible to use mixtures of polyamides, which may be mixtures of aliphatic polyamides and semiaromatic polyamides and mixtures of aliphatic polyamides and cycloaliphatic polyamides.

[0090] According to one embodiment, the mono-material footwear comprises 15 to 65% by weight, in particular 25 to 55% by weight, of one or more thermoplastic polymers chosen from polyamides and copolyamides. For example, it may comprise 15 to 20% by weight, or 20 to 25% by weight, or 25 to 30% by weight, or 30 to 35% by weight, or 35 to 40% by weight, or 40 to 45% by weight, or 50 to 55% by weight, or 55 to 60% by weight, or 60 to 65% by weight of polyamides and / or copolyamides, relative to the weight of the mono-material footwear.

[0091] Polyether with amide blocks (PEBA)

[0092] The mono-material article of footwear of the invention further comprises one or more PEBAs.According to one embodiment, the article of footwear comprises a part consisting essentially of a PEBA alone or in admixture with one or more polyamides or copolyamides as described above.

[0093] According to one embodiment, the thermoplastic elastomer is a polyether with amide blocks (PEBA). In these copolymers, the rigid block is a polyamide comprising at least one unit of the Z- or XY-type:

[0094] Z is a lactam or an amino acid having 6 to 18 carbon atoms,

[0095] X is a diamine having 4 to 48 carbon atoms, and

[0096] • Y is a diacid having 6 to 48 carbon atoms.

[0097] PEBAs result from the polycondensation of polyamide blocks with reactive ends (rigid or hard blocks) with polyether blocks with reactive ends (flexible or soft blocks), such as, in particular, the following polycondensation:

[0098] 1) a polyamide block having a diamine chain end and a polyoxyalkylene block having a dicarboxylic acid chain end;

[0099] 2) Polyamide blocks with dicarboxylic acid chain ends with polyetherdiols (α,ω-dihydroxylated aliphatic polyoxyalkylene blocks), in this particular case the products obtained are polyetheresteramides.

[0100] Polyamide blocks with dicarboxylic acid chain ends originate, for example, from the condensation of polyamide precursors in the presence of a chain-limiting dicarboxylic acid.Polyamide blocks with diamine chain ends originate, for example, from the condensation of polyamide precursors in the presence of a chain-limiting diamine.

[0101] Three types of polyamide blocks can advantageously be used.

[0102] According to a first type, the polyamide blocks are derived from the condensation of dicarboxylic acids, in particular those containing from 4 to 36 carbon atoms, preferably those containing from 4 to 20 carbon atoms, more preferably from 6 to 18 carbon atoms, with aliphatic or aromatic diamines, in particular those containing from 2 to 20 carbon atoms, preferably those containing from 6 to 14 carbon atoms.

[0103] As examples of dicarboxylic acids, mention may be made of 1,4-cyclohexanedicarboxylic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, tridecanedicarboxylic acid, hexadecanedicarboxylic acid and octadecanedicarboxylic acid, terephthalic acid and isophthalic acid, and dimerized fatty acids.

[0104] As examples of diamines, mention may be made of tetramethylenediamine, hexamethylenediamine, 1,10-decamethylenediamine, dodecamethylenediamine, trimethylhexamethylenediamine, isomers of bis(4-aminocyclohexyl)methane (BACM), isomers of bis(3-methyl-4-aminocyclohexyl)methane (BMACM) and isomers of 2,2-bis(3-methyl-4-aminocyclohexyl)propane (BMACP), p-aminodicyclohexylmethane (PACM), isophoronediamine (IPDA), 2,6-bis(aminomethyl)norbornane (BAMN) and piperazine (Pip).

[0105] Advantageously, use is made of the polyamide blocks PA 412, PA 414, PA 418, PA 516, PA 610, PA 612, PA 613, PA 614, PA 618, PA 912, PA 1010, PA 1012, PA 1014, PA 1018 and PA 129. In the PA XY notation, X represents the number of carbon atoms resulting from the diamine residue in the conventional manner and Y represents the number of carbon atoms resulting from the diacid residue in the conventional manner.

[0106] According to a second type, the polyamide blocks are produced by the condensation of one or more α,ω-aminocarboxylic acids and / or one or more lactams containing 6 to 12 carbon atoms in the presence of dicarboxylic acids or diamines containing 4 to 18 carbon atoms. As examples of lactams, mention may be made of caprolactam, enantholactam and lauryl lactam. As examples of α,ω-aminocarboxylic acids, mention may be made of aminocaproic acid, 7-aminoheptanoic acid, 10-aminodecanoic acid, 11-aminoundecanoic acid and 12-aminododecanoic acid.

[0107] Advantageously, the second type of polyamide blocks are PA 10 (polydecamide), PA 11 (polyundecamide), PA 12 (polydodecamide) or PA 6 (polycaprolactam) blocks. In the notation PAX, X represents the number of carbon atoms derived from the amino acid residue.

[0108] According to a third type, the polyamide blocks result from the condensation of at least one α,ω-aminocarboxylic acid or lactam with at least one diamine and at least one dicarboxylic acid.

[0109] In this case, the polyamide PA blocks are prepared by the following polycondensation:

[0110] - one or more linear aliphatic or aromatic diamines containing X carbon atoms;

[0111] - one or more dicarboxylic acids containing Y carbon atoms; and

[0112] - one or more comonomers {Z} selected from lactams and equimolar mixtures of α,ω-aminocarboxylic acids containing Z carbon atoms and at least one diamine containing X1 carbon atoms and at least one dicarboxylic acid containing Y1 carbon atoms, (X1,Y1) being different from (X,Y),

[0113] - the comonomer(s) {Z} are preferably introduced in a weight proportion advantageously up to 50%, preferably up to 20%, even more advantageously up to 10% relative to the total polyamide precursor monomers;

[0114] - in the presence of a chain limiter selected from dicarboxylic acids.

[0115] Advantageously, a dicarboxylic acid containing Y carbon atoms is used as chain limiter, which is introduced in a stoichiometric excess relative to the diamine or diamines.

[0116] According to one variant of this third type, the polyamide blocks result from the condensation of at least two α,ω-aminocarboxylic acids or at least two lactams containing 6 to 12 carbon atoms or a lactam and an aminocarboxylic acid not having the same number of carbon atoms, optionally in the presence of a chain limiter.

[0117] As examples of aliphatic α,ω-aminocarboxylic acids, mention may be made of aminocaproic acid, 7-aminoheptanoic acid, 10-aminodecanoic acid, 11-aminoundecanoic acid and 12-aminododecanoic acid. As examples of lactams, mention may be made of caprolactam, enantholactam and lauryl lactam. As examples of aliphatic diamines, mention may be made of hexamethylenediamine, dodecamethylenediamine and trimethylhexamethylenediamine.

[0118] As an example of alicyclic diacids, mention may be made of 1,4-cyclohexanedicarboxylic acid. As examples of aliphatic diacids, mention may be made of succinic acid, adipic acid, azelaic acid, suberic acid, sebacic acid, dodecanedicarboxylic acid and dimer fatty acids. These dimer fatty acids preferably have a dimer content of at least 98%; they are preferably hydrogenated; they are, for example, the products sold under the trade name Pripol by Croda, or under the trade name Empol by BASF, or under the trade name Radiacid by Oleon, and polyoxyalkylene α,ω-diacids. As examples of aromatic diacids, mention may be made of terephthalic acid (T) and isophthalic acid (I).

[0119] As examples of alicyclic diamines, mention may be made of isomers of bis(4-aminocyclohexyl)methane (BACM), isomers of bis(3-methyl-4-aminocyclohexyl)methane (BMACM), isomers of 2,2-bis(3-methyl-4-aminocyclohexyl)propane (BMACP), and para-aminodicyclohexylmethane (PACM). Other commonly used diamines may be isophoronediamine (IPDA), 2,6-bis(aminomethyl)norbornane (BAMN) and piperazine.

[0120] As examples of polyamide blocks of the third type, the following may be mentioned:

[0121] - PA 66 / 6, in which 66 represents a hexamethylenediamine unit condensed with adipic acid and 6 represents a unit resulting from the condensation of caprolactam;

[0122] - PA 66 / 610 / 11 / 12, wherein 66 represents hexamethylenediamine condensed with adipic acid, 610 represents hexamethylenediamine condensed with sebacic acid, 11 represents the unit resulting from the condensation of aminoundecanoic acid, and 12 represents the unit resulting from the condensation of lauryl lactam.

[0123] The notations PA X / Y, PA X / Y / Z etc. relate to copolyamides, wherein X, Y, Z etc. represent homopolyamide units as described above.

[0124] Advantageously, the polyamide blocks of the copolymer used in the present invention comprise polyamide blocks PA 6, PA 10, PA 11, PA 12, PA 54, PA 59, PA 510, PA 512, PA 513, PA 514, PA 516, PA 518, PA 536, PA 64, PA 66, PA 69, PA 610, PA 612, PA 613, PA 614, PA 616, PA 618, PA 636, PA 104, PA 109, PA 1010, PA 1012, PA 1013, PA 1014, PA 1016, PA 1018, PA 1036, PA 10T, PA 124, PA 129, PA 1210, PA 1212, PA 1213, PA 1214 12, PA 1010, PA 1012 or PA 11 / 12, or a mixture or copolymer thereof, more preferably a polyamide block PA 11, PA 12, PA 11 / 12, PA 6 or PA 612, or a mixture or copolymer thereof.

[0125] The polyether blocks essentially comprise or consist of alkylene oxide units.

[0126] The polyether blocks may in particular be PEG (polyethylene glycol) blocks (i.e. blocks composed of ethylene oxide units), and / or PPG (propylene glycol) blocks (i.e. blocks composed of propylene oxide units), and / or PO3G (polytrimethylene glycol) blocks (i.e. blocks composed of polytrimethylene glycol ether units), and / or PTMG blocks (i.e. blocks composed of tetramethylene glycol units, also known as polytetrahydrofuran units). The PEBA copolymers may contain several types of polyethers in their chain, the copolyethers possibly being in block or statistical form.

[0127] It is also possible to use blocks obtained by oxyethylation of bisphenols, for example bisphenol A. The latter products are described in particular in EP 613 919.

[0128] The polyether blocks may also consist of ethoxylated primary amines. As examples of ethoxylated primary amines, mention may be made of products of the formula:

[0129] [Chemical formula 1]

[0130]

[0131] wherein m and n are integers between 1 and 20, and x is an integer between 8 and 18. These products are commercially available, for example, under the trade name Noramox® from the company CECA and under the trade name Genamin® from the company Clariant.

[0132] The polyether diol blocks are co-condensed with carboxyl-terminated polyamide blocks. The general process for the two-step preparation of PEBA copolymers containing ester bonds between PA blocks and PE blocks is known and described, for example, in FR 2846332. The general process for the preparation of PEBA copolymers with amide bonds between PA blocks and PE blocks is known and described, for example, in EP 1482011. The polyether blocks can also be mixed with polyamide precursors and chain-limiting diacids to prepare polymers containing polyamide blocks and polyether blocks with randomly distributed units (one-step process).

[0133] PEBAs may contain amine chain ends, provided that they contain OH chain ends. PEBAs containing amine chain ends can be produced by the polycondensation of polyamide blocks with dicarboxylic acid chain ends with polyoxyalkylene blocks with diamine chain ends, obtained, for example, by cyanoethylation and hydrogenation of α,ω-dihydroxylated aliphatic polyoxyalkylene blocks (known as polyether diols).

[0134] PEBAs are commercially available. Mention may be made in particular of the products sold under the name Pebax® by Arkema, under the name Vestamid® by Evonik, under the name Grilamid® by EMS and under the name Pelestat® by Sanyo.

[0135] Although the above-mentioned block copolymers generally comprise at least one polyamide block and at least one polyether block, PEBAs in the sense of the present description may also comprise two, three, four (or even more) different blocks chosen from those described in the present description, provided that these blocks include at least polyamide and polyether blocks.

[0136] For example, the copolymer may be a segmented block copolymer comprising three different types of blocks (or a "triblock" copolymer), resulting from the condensation of the above-mentioned blocks. The triblock may, for example, be a copolymer comprising a polyamide block, a polyester block and a polyether block, or a copolymer comprising a polyamide block and two different polyether blocks (e.g., a PEG block and a PTMG block). The triblock is preferably a copolyetheresteramide.

[0137] The number-average molar mass of the polyamide blocks in the PEBA copolymers is preferably from 400 to 20 000 g / mol, more preferably from 500 to 10 000 g / mol.

[0138] The number average molar mass of the polyether blocks is preferably from 100 to 6000 g / mol, more preferably from 200 to 3000 g / mol.

[0139] The number average molar mass is set by the content of chain limiter. It can be calculated according to the following equation:

[0140] M n =n 单体 ×MW 重复单元 / n 限链剂 +MW 限链剂

[0141] In this formula, n 单体 represents the number of moles of monomer, n 限链剂 represents the number of moles of excess diacid limiting agent, MW 重复单元 represents the molar mass of the repeating unit, and MW 限链剂 represents the molar mass of the excess diacid.

[0142] The number average molar masses of the polyamide blocks and polyether blocks can be measured by gel permeation chromatography (GPC) before copolymerization of the blocks.

[0143] Advantageously, the mass ratio of the polyamide block relative to the polyether block of the copolymer is from 0.1 to 20, preferably from 0.5 to 18, even more preferably from 0.6 to 15. This mass ratio can be calculated by dividing the number average molar mass of the polyamide block by the number average molar mass of the polyether block. Advantageously, the polyamide block-polyether block copolymer has a Shore D hardness between 10D and 70D, preferably between 25D and 45D.

[0144] Advantageously, the PEBA has a concentration of OH functional groups of 0.002 to 0.2 meq / g, preferably 0.005 to 0.1 meq / g, more preferably 0.01 to 0.08 meq / g, and / or a concentration of COOH functional groups of 0.002 to 0.2 meq / g, preferably 0.005 to 0.1 meq / g, more preferably 0.01 to 0.08 meq / g.

[0145] The concentration of COOH functions can be determined potentiometrically and the concentration of OH functions can be determined by proton NMR. The measurement protocol is described in detail in the article "Synthesis and characterization of poly(copolyethers-block-polyamides) - II. Characterization and properties of multiblockcopolymers", Maréchal et al., Polymer, Vol. 41, 2000, pp. 3561-3580.

[0146] Preferably, the polyamide blocks of the PEBA are selected from PA 11, PA 12, PA 10, PA 6, PA 610, PA 612, PA1010, PA 1012, PA 6 / 11, PA 6 / 12, PA 11 / 12, PA 6 / 11 / 12, PA 6 / 66 / 12, PA 6 / 1010, PA 6 / 1012 and PA 6 / 1010 / 1012, preferably PA 11, PA 12, PA 6, PA 612 and PA 11 / 12. Advantageously, the polyether blocks of the PEBA are polyethylene glycol and / or polytetrahydrofuran blocks.

[0147] According to one embodiment, the PEBA copolymer comprises a polyamide block as defined above and a block derived from PTMG, for example: a PA 6 / 11 block and a block derived from PTMG, a PA 6 / 12 block and a block derived from PTMG, a PA11 / 12 block and a block derived from PTMG, a PA 6 / 11 / 12 block and a block derived from PTMG, a PA 6 / 66 / 12 block and a block derived from PTMG, a PA 6 / 1010 block and a block derived from PTMG, a PA 6 / 1012 block and a block derived from PTMG, a PA 6 / 1010 / 1012 block and a block derived from PTMG, a PA 6 / 1012 / 12 block and a block derived from PTMG, a PA 6 block and a block derived from PTMG, a PA 11 block and a block derived from PTMG, a PA The PA 12 blocks and the blocks derived from PTMG, the PA 6 blocks and the blocks derived from PEG, the PA 11 blocks and the blocks derived from PEG, and the PA 12 blocks and the blocks derived from PEG.

[0148] Particularly preferred PEBA copolymers in the context of the present invention are copolymers comprising blocks from: PA10 and PEG; PA 10 and PTMG; PA 11 and PEG; PA 11 and PTMG; PA 12 and PEG; PA 12 and PTMG; PA 610 and PEG; PA 610 and PTMG; PA 6 and PEG; PA 6 and PTMG; PA 612 and PEG; PA 612 and PTMG.

[0149] Advantageously, the PEBA may be a recycled PEBA and / or a partially or completely bio-based PEBA.

[0150] According to one embodiment, the weight proportion of the polyether block in the copolymer is at least 50% relative to the total weight of the copolymer. Preferably, the mass proportion of the polyether block is 45 to 85% relative to the total weight of the copolymer, more preferably 50 to 80%, and in particular 60 to 70% relative to the total weight of the copolymer.

[0151] The mass ratio of the blocks in the copolymer can be determined by the number average molar mass of the blocks, which can be expressed by 1 H NMR determination.

[0152] Preferably, the polyether having amide blocks (PEBA) is a linear (non-crosslinked) copolymer.

[0153] According to one embodiment, the mono-material article of footwear comprises 35 to 85% by weight, in particular 45 to 75% by weight, of one or more thermoplastic polymers chosen from PEBAs. For example, it may comprise 35 to 40% by weight, or 40 to 45% by weight, or 45 to 50% by weight, or 50 to 55% by weight, or 55 to 60% by weight, or 60 to 65% by weight, or 70 to 75% by weight, or 75 to 80% by weight, or 80 to 85% by weight of PEBAs relative to the weight of the mono-material article of footwear.

[0154] additive

[0155] To achieve desired properties but also for aesthetic purposes, a mono-material article of footwear may also include certain additives in some or all of the components.

[0156] In their broadest definition, additives are compounds that do not fall within the definition of components (i) and (ii), ie they are neither polyamides or copolyamides nor PEBAs.

[0157] Among the additives, mention may in particular be made of fireproofing agents, flame retardants, anti-UV agents, antioxidants, antiwear agents, light stabilizers, impact modifiers, antistatic agents, optical brighteners, nucleating agents, plasticizers, adhesion promoters, adhesives, lubricants, blowing agents and pigments.

[0158] Fillers and reinforcing agents may also be present as additives. Mention may be made in particular of fiber reinforcements such as glass or carbon fibers, short or continuous and optionally coated with resin, or alternatively fibers of vegetable matter or mineral fibers. As a variant, non-fibrous reinforcements may be envisaged, for example solid glass beads, but also lightweight reinforcements such as hollow glass beads or encapsulated foaming agents.

[0159] More generally, it may be desirable to provide limited amounts of polymers other than polyamides, copolyamides, or PEBAs in articles of footwear.

[0160] Therefore, the parts of the article of footwear are generally assembled using an adhesive. Preferably, this is an adhesive of polyamide or copolyamide or alternatively PEBA. Advantageously, it can be a copolyamide. Alternatively, the adhesive employed can also be chosen in particular from polyurethanes.

[0161] In one embodiment, the mono-material footwear may therefore include an additive in the form of a polymer that is not a polyamide, a copolyamide or a PEBA. Preferably, if present, such an adhesive is present in a low content, for example 0.01% to 10% by weight, advantageously 0.1% to 5% by weight and very particularly 1% to 2.5% by weight relative to the weight of the footwear.

[0162] Generally, the mono-material footwear article contains 0 to 15 wt % additives relative to the weight of the mono-material footwear article, for example 0 to 2.5 wt %, or 2.5 to 5 wt %, or 5 to 7.5 wt %, or 7.5 to 10 wt %, or 10 to 12.5 wt %, or 12.5% ​​to 15 wt % additives.

[0163] Depending on the design for a mono-material article of footwear, the article includes components comprising one or more polyamides or copolyamides as the only polymers and other components comprising one or more PEBAs as the only polymers.

[0164] Alternatively, a mono-material article of footwear may also include some or all components made from a polyamide or co-polyamide alloy in combination with PEBA.

[0165] Finally, a mono-material article of footwear may include components comprising a single polymer series and other components made from alloys of polyamide and / or copolyamide in combination with PEBA.

[0166] Method for manufacturing a single-material article of footwear

[0167] The monomaterial articles of footwear of the present invention may be manufactured by any method known in the art.

[0168] In particular, according to another aspect, the present invention relates to a method for manufacturing a single-material article of footwear according to the present invention, comprising the following steps:

[0169] I. Providing a material comprising one or more polyamides or copolyamides, one or more PEBAs and / or one or more additives suitable for use in various components of an article of footwear;

[0170] II. manufacturing components of an article of footwear from corresponding thermoplastic materials; and

[0171] III. assembling the components of the article of footwear, where appropriate with the aid of an adhesive, to form a finished article of footwear,

[0172] The materials used are selected so that the finished footwear article contains 15 to 65% by weight of one or more thermoplastic polymers chosen from polyamides and copolyamides; 35 to 85% by weight of one or more thermoplastic elastomers chosen from PEBA; and 0 to 15% by weight of additives.

[0173] According to one embodiment, the materials used are selected so that the finished article of footwear comprises 25 to 55% by weight of one or more thermoplastic polymers chosen from polyamides and copolyamides; 45 to 75% by weight of one or more thermoplastic elastomers chosen from PEBA; and 0 to 15% by weight of additives.

[0174] Therefore, materials based on polyamide, copolyamide or PEBA will be specifically selected for the various parts of the footwear, in particular those forming the upper and those forming the sole. Depending on the stresses of the various parts, in addition to additives, a material consisting of polyamide or copolyamide alone, PEBA alone or alternatively a mixture of these polymers will be selected.

[0175] According to one embodiment, a mono-material article of footwear according to the invention can be designed with an upper consisting essentially of polyamide, a lace consisting essentially of polyamide and a sole consisting essentially of PEBA.

[0176] Thus, for example, a mono-material article of footwear according to the invention may comprise an upper comprising a textile component made of polyamide, laces made of polyamide, and both a midsole and an outsole made of PEBA, as shown in Table 1 below.

[0177] [Table 1]

[0178]

[0179] The properties of the components of the mono-material footwear can be optimized accordingly by selecting certain specific grades of polyamide, co-polyamide or PEBA. In addition, alloys of these polymers can be used. The weight of the corresponding components can then also be adjusted so that the mono-material footwear has a ratio of polyamide / co-polyamide to PEBA as claimed. The mono-material footwear thus designed can make it possible to obtain a recycled composition with good properties.

[0180] Method for recycling a mono-material article of footwear

[0181] Due to the fact that it consists essentially of thermoplastic material, the mono-material footwear of the present invention has the advantage of being easily recyclable. In addition, the footwear of the present invention can also be recycled completely safely, since they do not have the risk of forming isocyanates like TPU-based footwear.

[0182] Therefore, according to another aspect, the present invention relates to a method for recycling a mono-material article of footwear according to the present invention, comprising the following steps:

[0183] (a) supplying used footwear;

[0184] (b) grinding the cleaned article of footwear to obtain a ground material;

[0185] (c) heating the ground material until it melts; and

[0186] (d) Extruding the melt into pellets.

[0187] A cleaning step may also be provided before or after step (b) to remove any dirt.

[0188] The ground footwear material obtained at the end of step (b) is generally in the form of shredded material. It comprises particles of variable shape and size, but most often of a size of the order of a few millimeters.

[0189] Depending on the intended application of the recycled product, it may be advantageous to add one or more virgin materials to the ground article of footwear obtained from the used article of footwear. Thus, according to one embodiment, the recycling method further comprises the following steps:

[0190] (e) adding new material to the ground used article of footwear either before or after step (d).

[0191] The new material may in particular be one or more thermoplastic polymers chosen from polyamides and copolyamides. Alternatively or in combination, it may also be one or more thermoplastic elastomers chosen from PEBA.

[0192] Specific additives may also be added, especially stabilizers and in particular chain extenders, making it possible to compensate for the aging of the material during its manufacture and previous use.

[0193] Recycled polymer composition

[0194] The mono-material footwear articles of the present invention can be recycled to produce materials with excellent properties. In particular, these materials have low density, good elastic recovery, suitable tensile modulus and stable intrinsic viscosity, which makes them suitable for use in demanding applications and multiple recycling cycles.

[0195] Although the recycled material obtained has advantageous mechanical properties, the fact remains that the recycled polymer is modified relative to the virgin polymer. In particular, thermal stresses and often oxidative stresses during the manufacture of the article of footwear, its use and its subsequent recycling affect some of its reactive functions.

[0196] The ground material and the compositions produced therefrom have the characteristic that the polymers present are obtained from used articles of footwear. During their use, articles of footwear are particularly exposed to air and light, as well as to the liquid perspiration of the person who wears them and to their degradation products by microorganisms.

[0197] According to another aspect, the present invention relates to a recycled polymer composition obtainable by the process according to the present invention.

[0198] The composition may especially consist of:

[0199] (a) 20 to 100% by weight, advantageously 30 to 99% by weight, even more preferably 50 to 98% by weight, of a granulated, ground, mono-material article of footwear consisting of:

[0200] a. 15 to 65% by weight, in particular 25 to 55% by weight, of one or more thermoplastic polymers selected from polyamides or copolyamides;

[0201] b. 35 to 85% by weight, in particular 45 to 75% by weight, of one or more thermoplastic elastomers selected from PEBA; and

[0202] c. 0% to 15% additives;

[0203] (b) 0 to 80% by weight, preferably 1 to 70% by weight and in particular 2 to 50% by weight of a virgin polymer chosen from polyamides, copolyamides and PEBAs, preferably from polyamides; and

[0204] (c) 0 to 50 wt %, preferably 5 to 40 wt %, more preferably 10 to 30 wt %, and especially 15 to 25 wt % of additives.

[0205] Preferably, the virgin polymer is selected from the preferred polyamides and copolyamides and PEBAs described above in the context of mono-material articles of footwear.

[0206] The optional additives of component (c) may in particular be chosen from the list of agents and compounds mentioned above in relation to the additives present in the mono-material article of footwear. Advantageously, these additives comprise fillers and reinforcements as mentioned above.

[0207] use

[0208] Due to these advantageous properties, the composition resulting from the recycling of the present mono-material article of footwear can be recycled for a variety of uses, and particularly for performance applications.

[0209] According to one embodiment, the composition obtained from recycling can be used to remanufacture footwear components, in particular those of mono-material footwear articles, in particular sports footwear articles. This variant is particularly advantageous because it represents a closed-loop recycling.

[0210] The present invention will be explained in more detail in the following examples.

[0211] Example

[0212] Unless otherwise stated, percentages are expressed hereinafter by weight relative to the total weight of the composition.

[0213] The following materials were used:

[0214] Polyamide 11: Rilsan® FMNO, a polyamide 11 homopolymer, has an intrinsic viscosity of 1.05 in solution, sold by Arkema.

[0215] PEBA 1: Pebax® RNew 40R53 SP01, sold by Arkema, having a hardness of 90 Shore A as measured after 3 s according to ISO standard 868:2003.

[0216] PEBA 2: Pebax® 2533 SD02, sold by Arkema, has a hardness of 75 Shore A as measured after 3 s according to ISO standard 868:2003.

[0217] PEBA 3: Pebax® RNew 72R53 SP01, sold by Arkema, has a hardness of 72 Shore D as measured after 3 s according to ISO standard 868:2003.

[0218] TPU 1: Elastollan® 1180A, sold by BASF, having a hardness of 80 Shore A as measured after 3 s according to ISO standard 868:2003.

[0219] TPU 2: Elastollan® 1164D, sold by BASF, having a hardness of 64 Shore D as measured after 3 s according to ISO standard 868:2003.

[0220] Antioxidant 1: Irganox® 245, sold by BASF.

[0221] Antioxidant 2: Irgafos® 168, sold by BASF.

[0222] Examples EI 1 to EI 2

[0223] Various formulations of polyamide and PEBA, whose compositions are shown in Table 2 below, were prepared by compounding in a co-rotating twin-screw extruder at a temperature of 230° C. in order to evaluate their behavior after ageing and recycling.

[0224] On leaving the extruder, the molten polymer was solidified by passing through a water bath at 25° C. and then chopped into pellets. They were then dried in an oven at 80° C. under reduced pressure for 8 hours to reach a residual moisture content of < 0.1%.

[0225] The products were then used by injection in the form of plates with dimensions of 100 × 100 × 2 mm at 250° C. These samples were UV aged for 1000 hours in a Xenon QSun enclosure to simulate their first lifetime.

[0226] The aged samples were chopped in a model RS2402 cutting mill from the supplier Getecha. The ground material was then melted again and homogenized in a co-rotating twin-screw extruder at 230° C. The molten polymer was solidified by passing through a water bath at 25° C. and then chopped into pellets of the recycled product, which were then dried under reduced pressure for 8 hours to reach a moisture content of less than 0.1%.

[0227] The pellets of the recycled product were finally injected at 250 °C to form the test pieces required for characterization: ISO 527 1A dumbbells (tensile), bars with dimensions of 80 × 10 × 4 mm (Charpy impact) and bars with dimensions of 100 × 100 × 2 mm 3 Prior to the measurement, the test pieces were conditioned for 15 days in a controlled atmosphere at 23° C. and 50% relative humidity.

[0228] The manufactured test pieces were then used to evaluate the mechanical properties of the formulations after recycling as follows.

[0229] A. Modulus and elongation at break under tensile load

[0230] Tensile modulus and elongation at break were measured on a Zwick dynamometer at 23 °C and 50% relative humidity according to ISO standard 527-1-2019.

[0231] B. Impact resistance

[0232] The energy dissipated during a notched Charpy impact (resilience) is measured at a temperature of -30°C according to ISO standard 179 / :1993 1eA.

[0233] C. Tear resistance

[0234] The tear resistance is measured on angular test pieces with a notch cut with a punch from a 100×100×2 mm plate. The test is carried out on a Zwick dynamometer at 23° C., 50% relative humidity and a speed of 500 mm / min according to ISO standard 34-1-2010.

[0235] D. Compounds generated in the recycling process

[0236] By checking at 2270 cm -1 The presence of isocyanate functional groups (toxic) is detected on diamond crystals by infrared FTIR spectroscopy in ATR mode, by the appearance of a specific absorption band at 1 Å. This measurement is carried out on pellets of the recycled product one hour after their extrusion.

[0237] [Comparative Examples EC A to EC E]

[0238] The TPU-based formulations comprising different proportions of polyamide and PEBA were prepared as shown in Examples EI 1 and EI 2 above, and the procedure for their aging and then the preparation of test pieces therefrom was identical, and the test pieces were evaluated in the same way.

[0239] The compositions of the formulations and the evaluation results are listed in Table 2 below.

[0240] [Table 2] Composition and recycling properties of the mixtures studied

[0241]

[0242] The results show that examples EI 1 and EI 2, representative of articles of footwear according to the invention, still exhibit good properties after recycling, which makes them advantageous as starting materials for the manufacture of performance articles, such as, in particular, articles of sports footwear. The combination of polyamide and PEBA in the specific ratios of the invention makes it possible in fact to obtain excellent mechanical properties in terms of modulus, as well as in terms of tear resistance and Charpy notched impact resistance.

[0243] Comparative Examples EC A, EC C, EC D and EC F, on the contrary, show that compositions that do not meet the criteria of the invention exhibit weak properties after recycling and therefore cannot be envisaged for demanding applications. In fact, when the article of footwear contains too much PEBA, the tensile modulus becomes insufficient and the tear resistance and impact resistance decrease, as shown in Examples EC A, EC C and EC D. When the article of footwear contains too much polyamide, the mixture has a very high tensile modulus, incompatible with reuse for the manufacture of articles of footwear, as shown in Comparative Example EC B. Finally, in addition to the low performances obtained, the recycling of TPU causes the formation of isocyanates, which makes the use of this material for recyclable articles difficult from the point of view of HSE.

[0244] Citation list

[0245] EP 3 081 109 B1

[0246] WO 2020 / 201370 A1

Claims

1. Single-material articles of footwear consisting of: (i) 15 to 65% by weight of one or more thermoplastic polymers selected from polyamides and copolyamides; (ii) 35 to 85% by weight of one or more thermoplastic elastomers selected from PEBA; and (iii) 0 to 15 wt % of additives.

2. The article of footwear according to claim 1, consisting of: (i) 25 to 55% by weight of one or more thermoplastic polymers selected from polyamides or copolyamides; (ii) 45 to 75% by weight of one or more thermoplastic elastomers selected from PEBA; and (iii) 0 to 15 wt % of additives.

3. A single-material footwear article according to claim 1 or 2, wherein component (i) comprises a polyamide or copolyamide selected from the group consisting of PA 612, PA 613, PA 912, PA 1010, PA 1012, PA 6, PA 11, PA12, PA 6 / 11, PA 6 / 12, PA 11 / 12, PA 6 / 11 / 12, PA 6 / 66 / 12, PA 6 / 1010, PA 6 / 1012, PA 6 / 1010 / 1012, PA 6 / 1012 / 12, PA 6 / 66 / 11 / 12 and PA 6 / 1010 / 1012 / 1014, alone or as a mixture.

4. The mono-material footwear article according to any one of claims 1 to 3, wherein component (ii) comprises a PEBA selected from the group consisting of PA 6 / 11 blocks and blocks derived from PTMG, PA 6 / 12 blocks and blocks derived from PTMG, PA 11 / 12 blocks and blocks derived from PTMG, PA 6 / 11 / 12 blocks and blocks derived from PTMG, PA 6 / 66 / 12 blocks and blocks derived from PTMG, PA 6 / 1010 blocks and blocks derived from PTMG, PA 6 / 1012 blocks and blocks derived from PTMG, PA 6 / 1010 / 1012 blocks and blocks derived from PTMG, PA 6 / 1012 / 12 blocks and blocks derived from PTMG, PA 6 blocks and blocks derived from PTMG, PA 11 blocks and blocks derived from PTMG, PA 6 / 11 / 12 blocks and blocks derived from PTMG, PA 6 / 66 / 12 blocks and blocks derived from PTMG, PA 6 / 1010 blocks and blocks derived from PTMG, PA 6 / 1012 blocks and blocks derived from PTMG, PA 6 / 1012 / 12 blocks and blocks derived from PTMG, PA 6 blocks and blocks derived from PTMG, PA 11 blocks and blocks derived from PTMG, PA The PA12 blocks and the blocks derived from PTMG, the PA6 blocks and the blocks derived from PEG, the PA11 blocks and the blocks derived from PEG, and the PA12 blocks and the blocks derived from PEG.

5. A mono-material footwear article as claimed in any one of claims 1 to 4, wherein the polyamide or copolyamide of component (i) has an average ratio of the number of carbon atoms per amide functional group of greater than 6, preferably greater than 8 and in particular 10 or more.

6. A mono-material footwear article as claimed in any one of claims 1 to 5, comprising as an additive 0 to 10 wt. %, preferably 0.1 to 4 wt. % of a binder.

7. The single-material article of footwear of claim 6, wherein the adhesive comprises or consists of polyurethane.

8. Method for manufacturing a single-material article of footwear as claimed in any one of claims 1 to 7, comprising the steps of: I. Providing a material comprising one or more polyamides or copolyamides, one or more PEBAs and / or one or more additives suitable for use in the various components of the article of footwear; II. manufacturing components of the article of footwear from corresponding thermoplastic materials; and III. assembling said components of said article of footwear, where appropriate with the aid of an adhesive, to form a finished article of footwear, The materials used are selected so that the finished footwear article comprises 15 to 65% by weight of one or more thermoplastic polymers selected from polyamides and copolyamides; 35 to 85% by weight of one or more thermoplastic elastomers selected from PEBA; and 0 to 15% by weight of additives.

9. A manufacturing method as claimed in claim 8, wherein the materials used are selected so that the finished footwear article comprises 25 to 55% by weight of one or more thermoplastic polymers chosen from polyamides and copolyamides; 45 to 75% by weight of one or more thermoplastic elastomers chosen from PEBA; and 0 to 15% by weight of additives.

10. A method for recycling a single-material article of footwear as claimed in any one of claims 1 to 7, comprising the steps of: (a) supplying used footwear; (b) grinding the cleaned article of footwear to obtain a ground material; (c) heating the ground material until it melts; as well as (d) Extruding the melt into pellets.

11. The recycling method of claim 10, further comprising the steps of: (e) adding new material to the ground used article of footwear either before or after step (d).

12. Recycled polymer composition obtainable by the process as claimed in claims 9 to 11.

13. A composition consisting of: (a) 20 to 100% by weight, advantageously 30 to 99% by weight, even more preferably 50 to 98% by weight, of a granulated, ground, mono-material article of footwear consisting of: a. 15 to 65% by weight, in particular 25 to 55% by weight, of one or more thermoplastic polymers selected from polyamides or copolyamides; b. 35 to 85% by weight, in particular 45 to 75% by weight, of one or more thermoplastic elastomers selected from PEBA; and c. 0% to 15% additives; (b) 0 to 80% by weight, preferably 1 to 70% by weight and in particular 2 to 50% by weight of a virgin polymer chosen from polyamides, copolyamides and PEBAs; and (c) 0 to 50% by weight of additives.

14. Use of a composition according to claim 12 or 13 for the manufacture of an article of footwear.

15. The use according to claim 14, wherein the article of footwear is a single-material article of footwear.

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