Thermoplastic polyurethane foam and copolymer foam with polyamide and polyether blocks

Abstract

The invention relates to a polymer foam comprising at least one thermoplastic polyurethane and at least one polyamide-polyether block copolymer, said foam having an OH group concentration of 0.002 meq / g to 0.2 meq / g. The invention also relates to a method for preparing such a foam and to an article comprising such a foam. Figure 1 is shown in the abstract.

Description

Title of the invention: Thermoplastic polyurethane foam and copolymer with polyamide and polyether blocks. Field of the invention

[0001] The present invention relates to polymer foams, comprising a thermoplastic polyurethane and a copolymer with polyamide and polyether blocks, as well as methods for preparing them. Technical background

[0002] Various polymer foams are used in particular in the field of sports equipment, such as soles or sole components, gloves, rackets or golf balls, personal protective equipment in particular for the practice of sport (vests, inner parts of helmets, shells...

[0003] Such applications require a set of particular physical properties ensuring a capacity for rebound, low permanent deformation in compression and an ability to endure repeated impacts without deforming and to return to the initial shape.

[0004] Document WO 2022 / 162048 relates to expanded particles comprising a first thermoplastic elastomer having a Shore D hardness of 20 to 90 and a second thermoplastic elastomer. The first thermoplastic elastomer is in particular a thermoplastic polyurethane, a thermoplastic polyetheramide, a thermoplastic copolyester, a polyetherester or a polyester ester, and the second thermoplastic elastomer is in particular a thermoplastic polyurethane, a thermoplastic polyetheramide, a polyetherester or a polyester ester or a thermoplastic styrene-butadiene copolymer.

[0005] There is a need to provide polymer foams with a fine and homogeneous cell structure, low density, good rebound resilience, and improved flexibility and tear resistance. Summary of the invention

[0006] The invention relates primarily to a polymer foam comprising: • at least one thermoplastic polyurethane, and • at least one copolymer with polyamide blocks and polyether blocks,

[0007] said foam having an OH function concentration of 0.002 meq / g to 0.2 meq / g as measured by proton NMR in a TFA / CDC13 (1 / 4 v / v) mixture.

[0008] In embodiments, at least a portion of the total polyamide-polyether block copolymer is covalently bonded to a thermoplastic polyurethane molecule by a urethane group, preferably an amount in less than or equal to 10% by weight, more preferably less than or equal to 5% by weight, of the polyamide and polyether block copolymer is covalently linked to a thermoplastic polyurethane molecule by a urethane function.

[0009] In embodiments, at least one polyamide block and polyether block copolymer has an OH function concentration, as measured by proton NMR in a TFA / CDC13 (1 / 4 v / v) mixture, of 0.003 to 0.15 meq / g, preferably of 0.005 meq / g to 0.1 meq / g, preferably again of 0.01 meq / g to 0.08 meq / g.

[0010] In embodiments, at least one polyamide block and polyether block copolymer has a COOH function concentration of 0.002 meq / g to 0.2 meq / g, preferably 0.005 meq / g to 0.1 meq / g, as measured by potentiometric titration in benzyl alcohol using a 0.02N tetrabutylammonium hydroxide solution.

[0011] In embodiments, the hot melt flow index MFI of thermoplastic polyurethane measured according to ASTM D1238 at 200°C under a load of 10 kg is from 10 to 100 g / 10 min, preferably from 25 to 80 g / 10 min, more preferably from 35 to 65 g / 10 min.

[0012] In embodiments, the quantity of polyamide blocks, as measured by proton NMR in a TFA / CDC13 (1 / 4 v / v) mixture, is at least 15% by weight, preferably at least 25% by weight, relative to the total weight of the foam

[0013] In embodiments, the polyamide block and polyether block copolymer comprises at least 30% by weight, preferably at least 40% by weight, of polyamide blocks, relative to the total weight of the copolymer, as measured by proton NMR in a TFA / CDC13 (1 / 4 v / v) mixture.

[0014] In embodiments, at least one thermoplastic polyurethane is a rigid block and flexible block copolymer, the rigid block content in the thermoplastic polyurethane, as measured by proton NMR in DMSO D6, being less than or equal to 90% by weight, preferably still less than or equal to 80% by weight, more preferably from 30 to 60% by weight.

[0015] In some embodiments, the foam comprises, relative to the total weight of the foam: • 20 to 45% by weight, preferably 25 to 40% by weight, of at least one thermoplastic polyurethane, and • 55 to 80% by weight, preferably 60 to 75% by weight, of at least one copolymer with polyamide blocks and polyether blocks.

[0016] In some embodiments, at least one thermoplastic polyurethane is a rigid-block, flexible-block copolymer, in which: • The flexible blocks are chosen from polyether blocks, polyester blocks, polycarbonate blocks and a combination thereof, preferably flexible blocks are selected from polyether blocks, polyester blocks, and a combination thereof, and are more preferably poly-tetrahydrofuran, polypropylene glycol and / or polyethylene glycol blocks; and / or rigid blocks comprise motifs from 4,4'-diphenylmethane dii-socyanate and / or 1,6-hexamethylene diisocyanate and, preferably, motifs from at least one chain extender selected from 1,3-propanediol, 1,4-butanediol and / or 1,6-hexanediol.

[0017] In embodiments, the polyamide blocks of the polyamide block and polyether block copolymer are blocks of polyamide 11, polyamide 12, polyamide 10, polyamide 6, polyamide 6.10, polyamide 6.12, polyamide 6.13, polyamide 10.9, polyamide 10.10, polyamide 10.12 and / or polyamide 12.9, preferably polyamide 11, polyamide 12, polyamide 6, polyamide 6.12, polyamide 6.13, polyamide 10.9 and / or polyamide 12.9; and / or the polyether blocks of the polyamide block and polyether block copolymer are blocks of polyethylene glycol and / or polypropylene glycol and / or polytetrahydrofuran.

[0018] In embodiments, the foam has a density, as measured at 23°C according to ISO 1183-1, less than or equal to 800 kg / m3, preferably less than or equal to 300 kg / m3, more preferably less than or equal to 230 kg / m3.

[0019] In embodiments, the foam has an Asker C hardness, as measured at 23°C according to ISO 7619-1, of 20 to 90, preferably of 25 to 70.

[0020] The invention also relates to a method for manufacturing a foam as described above, comprising the following steps: • the supply of a polymer composition comprising at least one thermoplastic polyurethane and at least one polyamide and polyether block copolymer; • the mixing of said polymer composition with an expanding agent; and • the foaming of the mixture of polymer composition and expanding agent.

[0021] In embodiments, the expanding agent is mixed with the polymer composition in the molten state, the foaming of the mixture being preferably carried out in a mold.

[0022] In embodiments, the expanding agent is a physical expanding agent and is mixed with the polymer composition in the form of a solid preform, the foaming of the mixture being preferably carried out in an autoclave.

[0023] In some embodiments, the step of supplying the polymer composition includes: • the mixing, preferably in an extruder, of at least one thermoplastic polyurethane and at least one molten polyamide and polyether block copolymer, so as to obtain the polymer composition; and • Optionally, shaping the polymer composition into granules or powder.

[0024] In some embodiments, the step of supplying the polymer composition includes: • the introduction into a reactor, preferably an extruder, of precursors of at least one thermoplastic polyurethane; • the introduction into the reactor of at least one copolymer with polyamide blocks and polyether blocks; • the synthesis of thermoplastic polyurethane in the reactor in the presence of the polyamide and polyether block copolymer, so as to obtain the polymer composition; and • Optionally, shaping the polymer composition into granules or powder.

[0025] The invention also relates to an article made of a foam as described above or comprising at least one element made of a foam as described above, preferably chosen from sports shoe soles, balls, gloves, personal protective equipment, rail soles, automotive parts, construction parts and electrical and electronic equipment parts.

[0026] The present invention makes it possible to meet the need expressed above. More particularly, it provides a regular, homogeneous polymer foam, exhibiting low density, high flexibility and good mechanical properties, particularly in terms of tear resistance and abrasion resistance, while maintaining excellent rebound resilience and low compression set.

[0027] This is achieved through the use, for the formation of the foam, of a mixture of a thermoplastic polyurethane (TPU) and a polyamide and polyether block copolymer (PEBA) giving the foam a specific concentration in OH function.

[0028] According to certain advantageous embodiments, covalent bonds are formed between at least a portion of the polyamide-polyether block copolymer and at least a portion of the thermoplastic polyurethane. More particularly, a reaction has taken place between at least a portion of the polyamide-polyether block copolymer and at least a portion of the thermoplastic polyurethane, and more particularly between the hydroxyl groups of the polyamide-polyether block copolymer and the isocyanate groups of the thermoplastic polyurethane, exposed by the decomposition, under certain conditions, of the thermoplastic polyurethane (into alcohol and polyisocyanate) or present in the precursors of the thermoplastic polyurethane. plastic. This reaction between at least a portion of the polyamide-polyether block copolymer and at least a portion of the thermoplastic polyurethane allows for better compatibility between these polymers. This results in improved foamability of the alloys, and therefore an improvement in the structure (finer and more homogeneous cell structure, lower density) and properties (in particular, higher rebound resilience, lower deformation and compression set, higher flexibility) of the foams obtained from these alloys. Brief description of the figures

[0029] [Fig. 1] shows the extensional rheometry curves obtained by an ARES G2 rheometer for the polymer composition at 180°C (curve A), for PEBA at 180°C (curve B), and for TPU at 200°C (curve C), as described in the examples below. Time (in s) is shown on the x-axis and extensional viscosity (in Pa·s) on the y-axis. Detailed description

[0030] The invention is now described in more detail and in a non-limiting manner in the following description.

[0031] Unless otherwise stated, all percentages are mass percentages.

[0032] In this text, the quantities indicated for a given species may apply to that species according to all its definitions (as mentioned in this text), including more restricted definitions.

[0033] The invention relates firstly to a foam comprising at least one copolymer with polyamide blocks and polyether blocks and at least one thermoplastic polyurethane.

[0034] Polyamide and polyether block copolymer (PEBA)

[0035] PEBAs result from the polycondensation of reactive-end polyamide blocks (rigid or hard blocks) with reactive ends and reactive-end polyether blocks (flexible or soft blocks), such as, among others, polycondensation:

[0036] 1) of polyamide blocks with diamine chain ends with polyoxyalkylene blocks with dicarboxylic chain ends;

[0037] 2) of polyamide blocks with dicarboxylic chain ends containing polyetherdiols (aliphatic α,co-dihydroxylated polyoxyalkylene blocks), the products obtained being, in this particular case, polyetheresteramides.

[0038] Polyamide blocks with dicarboxylic acid ends are obtained, for example, from the condensation of polyamide precursors in the presence of a chain-limiting dicarboxylic acid. Polyamide blocks with diamine chain ends are obtained, for example, from the condensation of polyamide precursors in the presence of a chain-limiting diamine.

[0039] Three types of polyamide blocks can be used advantageously.

[0040] According to a first type, the polyamide blocks are obtained from the condensation of a dicarboxylic acid, in particular those having 4 to 36 carbon atoms, preferably those having 4 to 20 carbon atoms, more preferably 6 to 18 carbon atoms, and an aliphatic or aromatic diamine, in particular those having 2 to 20 carbon atoms, preferably those having 6 to 14 carbon atoms.

[0041] Examples of dicarboxylic acids include 1,4-cyclohexyldicarboxylic acid, butanedioic, adipic, azelaic, suberic, sebacic, dodecanedicarboxylic, octadecanedicarboxylic acids and terephthalic and isophthalic acids, as well as dimerized fatty acids.

[0042] Examples of diamines include tetramethylenediamine, rhexamethylenediamine, 1,10-decamethylenediamine, dodecamethylenediamine, trimethylhexamethylenediamine, isomers of bis-(4-aminocyclohexyl)-methane (BACM), bis-(3-methyl-4-aminocyclohexyl)methane (BMACM), and 2-2-bis-(3-methyl-4-aminocyclohexyl)-propane (BMACP), para-amino-di-cyclo-hexyl-methane (PACM), isophoronediamine (IPDA), 2,6-bis-(aminomethyl)-norbornane (BAMN) and piperazine (Pip).

[0043] Advantageously, polyamide blocks PA 4.12, PA 4.14, PA 4.18, PA 6.10, PA 6.12, PA 6.14, PA 6.18, PA 9.12, PA 10.10, PA 10.12, PA 10.14 and / or PA 10.18 are used. In the PA XY notation, X represents the number of carbon atoms from the diamine residues, and Y represents the number of carbon atoms from the diacid residues, in a conventional manner.

[0044] According to a second type, the polyamide blocks result from the condensation of one or more α,co-aminocarboxylic acids and / or one or more lactams having from 6 to 12 carbon atoms in the presence of a dicarboxylic acid having from 4 to 18 carbon atoms or a diamine. Examples of lactams include ca-prolactam, oenantholactam, and lauryllactam. Examples of α,co-aminocarboxylic acids include aminocaproic, 7-aminoheptanoic, 10-aminodecanoic, 11-aminoundecanoic, and 12-aminododecanoic acids.

[0045] Advantageously, the polyamide blocks of the second type are blocks of PA 10 (polydecanamide), PA 11 (polyundecanamide), PA 12 (polydodecanamide), or PA 6 (polycaprolactam). In the PA X notation, X represents the number of carbon atoms derived from amino acid residues or lactam residues.

[0046] According to a third type, the polyamide blocks result from the condensation of at least one α,co-aminocarboxylic acid (or a lactam), at least one diamine and at least one dicarboxylic acid.

[0047] In this case, the polyamide PA blocks are prepared by polycondensation: • of the linear or aromatic aliphatic diamine(s) having X carbon atoms; • of the dicarboxylic acid(s) having Y carbon atoms; and • of the comonomer(s) {Z}, chosen from the lactams and acids a,co-aminocarboxylic acids having Z carbon atoms and equimolar mixtures of at least one diamine having XI carbon atoms and at least one dicarboxylic acid having Y1 carbon atoms, (XI, YI) being different from (X, Y), • said comonomer(s) {Z} being introduced in a weight proportion advantageously up to 50%, preferably up to 20%, even more advantageously up to 10% relative to all the polyamide precursor monomers; • in the presence of a chain limiter chosen from among the dicarboxylic acids.

[0048] Advantageously, the dicarboxylic acid having Y carbon atoms is used as the chain limiter, which is introduced in excess with respect to the stoichiometry of the diamine(s).

[0049] According to a variant of this third type, the polyamide blocks result from the condensation of at least two α,co-aminocarboxylic acids or at least two lactams having from 6 to 12 carbon atoms, or of a lactam and an aminocarboxylic acid not having the same number of carbon atoms, possibly in the presence of a chain-limiting agent. Examples of aliphatic α,co-aminocarboxylic acids include aminocaproic, 7-aminoheptanoic, 10-aminodecanoic, 11-aminoundecanoic, and 12-aminododecanoic acids. Examples of lactams include caprolactam, oenantholactam, and lauryllactam. Examples of aliphatic diamines include hexamethylenediamine, dodecamethylenediamine, and trimethylhexamethylenediamine. An example of cycloaliphatic diacid is 1,4-cyclohexyldicarboxylic acid.Examples of aliphatic diacids include butanedioic, adipic, azelaic, suberic, sebacic, and dodecanedicarboxylic acids, as well as α,β-diacid polyoxyalkylenes and dimerized fatty acids. These dimerized fatty acids are the product of the dimerization reaction of fatty acids (generally containing 18 carbon atoms, often a mixture of oleic and / or linoleic acids); they preferably have a dimer content of at least 98%; preferably they are hydrogenated; and they are preferably a mixture comprising 0 to 15% by weight of Cl8 monoacids, 60 to 99% by weight of C36 diacids, and 0.2 to 35% by weight of C54 or higher triacids or polyacids. This includes, for example, products marketed under the brand name "PRIPOL" by the company "CRODA", or under the brand name EMPOL by the company BASF. or under the brand name Radiacid by the company OLEON. Examples of aromatic diacids include terephthalic (T) and isophthalic (I) acids. Examples of cycloaliphatic diamines include the isomers of bis-(4-aminocyclohexyl)methane (BACM), bis-(3-methyl-4-aminocyclohexyl)methane (BMACM), and 2-2-bis-(3-methyl-4-aminocyclohexyl)propane (BMACP), and para-amino-di-cyclohexylmethane (PACM). Other commonly used diamines include isophoronediamine (IPDA), 2,6-bis-(aminomethyl)norbornane (BAMN), and piperazine.

[0050] Examples of third-type polyamide blocks include: • PA 6.6 / 6, where 6.6 designates hexamethylenediamine motifs condensed with adipic acid and 6 designates motifs resulting from the condensation of ca-prolactam; • PA 6.6 / 6.10 / 11 / 12, where 6.6 denotes hexamethylenediamine condensed with adipic acid, 6.10 denotes hexamethylenediamine condensed with sebacic acid, 11 denotes motifs resulting from the condensation of ami-noundecanoic acid and 12 denotes motifs resulting from the condensation of lauryllactam.

[0051] The notations PA X / Y, PA X / Y / Z, etc. refer to copolyamides in which X, Y, Z, etc. represent homopolyamide units as described above.

[0052] Advantageously, the polyamide blocks of the copolymer used in the invention comprise (or consist of) polyamide blocks PA 6, PA 10, PA 11, PA 12, PA 5.4, PA 5.9, PA 5.10, PA 5.12, PA 5.13, PA 5.14, PA 5.16, PA 5.18, PA 5.36, PA 6.4, PA 6.6, PA 6.9, PA 6.10, PA 6.12, PA 6.13, PA 6.14, PA 6.16, PA 6.18, PA 6.36, PA 10.4, PA 10.9, PA 10.10, PA 10.12, PA 10.13, PA 10.14, PA 10.16, PA 10.18, PA 10.36, PA 10.T, PA 12.4, PA 12.9, PA 12.10, PA 12.12, PA 12.13, PA 12.14, PA 12.16, PA 12.18, PA 12.36, PA 12.T, or mixtures or copolymers thereof; and preferably comprise, or consist of, blocks of polyamide PA 6, PA 10, PA 11, PA 12, PA 6.10, PA 6.12, PA 6.13, PA 10.9, PA 10.10, PA 10.12, PA 12.9, or mixtures or copolymers thereof, more preferably blocks of polyamide PA 6, PA 10, PA 11, PA 12, PA 6.10, PA 6.12, PA 6.13, PA 10.9, PA 12.9, or mixtures or copolymers thereof, more preferably blocks of polyamide PA 6, PA 11, PA 12, PA 6.12, PA 6.13, PA 10.9, PA 12.9, or mixtures or copolymers thereof.

[0053] The polyether blocks are made up of alkylene oxide motifs.

[0054] Polyether blocks may in particular be PEG (polyethylene glycol) blocks that is to say, composed of ethylene oxide motifs, and / or PPG (propylene glycol) blocks, that is to say, composed of propylene oxide motifs, and / or PO3G blocks (polytrimethylene glycol), i.e., composed of polytrimethylene glycol ether units, and / or PTMG blocks, i.e., composed of tetramethylene glycol units, also called polytetrahydrofuran. Preferably, the polyether blocks of PEBA are polyethylene glycol and / or polypropylene glycol and / or polytetrahydrofuran blocks. PEBA copolymers may include several types of polyethers in their chain; the copolyethers may be block or random.

[0055] Blocks obtained by oxyethylation of bisphenols, such as bisphenol A, can also be used. These latter products are described in particular in document EP 613919.

[0056] Polyether blocks can also be made of ethoxylated primary amines. Examples of ethoxylated primary amines include products with the following formulas:

[0057] [Chem.l] H—(OCH2CH2)m —N—(CH2CH2O)n—H (CH2)X ch3

[0058] in which m and n are integers between 1 and 20 and x is an integer between 8 and 18. These products are for example available commercially under the brand NORAMOX® of the company CECA and under the brand GENAMIN® of the company CLARIANT.

[0059] Preferably, for the preparation of PEBA, polyetherdiol blocks are copoly-condensed with polyamide blocks with carboxylic ends.

[0060] The general two-step method for preparing PEBA copolymers having ester linkages between PA blocks and PE blocks is known and is described, for example, in document FR 2846332. The general method for preparing PEBA copolymers having amide linkages between PA blocks and PE blocks is known and described, for example, in document EP 1482011. Polyether blocks can also be mixed with polyamide precursors and a diacid chain limiter to prepare polymers with polyamide and polyether blocks having statistically distributed motifs (one-step process).

[0061] The PEBA may include amine chain ends. PEBAs including amine chain ends may result from the polycondensation of polyamide blocks with dicarboxylic chain ends with polyoxyalkylene blocks with diamine chain ends, obtained for example by cyanoethylation and hydrogenation of aliphatic α,co-dihydroxylated poly-oxyalkylene blocks (polyetherdiols).

[0062] Of course, the designation PEBA in the present description of the invention is This also applies to PEBAX® marketed by Arkema, Vestamid® marketed by Evonik®, Grilamid® marketed by EMS, Pelestat® PEBA type marketed by Sanyo, or any other PEBA from other suppliers.

[0063] The PEBAs usable in the invention include copolymers comprising a single polyamide block and a single polyether block, but also copolymers comprising three, four (or even more) different blocks chosen from those described in this description, provided that these blocks include at least one polyamide block and one polyether block.Furthermore, the PEBAs usable in the invention include copolymers comprising, in addition to polyamide and polyether blocks, one or more blocks of another nature, in particular chosen from the group consisting of polyester blocks, polysiloxane blocks, such as polydimethylsiloxane (or PDMS) blocks, polyolefin blocks, polycarbonate blocks, and mixtures thereof, preferably chosen from the group consisting of polyester blocks, polysiloxane blocks, and mixtures thereof.

[0064] For example, the copolymer may be a segmented block copolymer comprising three different types of blocks (or “triblock”), resulting from the condensation of several of the blocks described above. Said 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, for example, a PEG block and a PTMG block.

[0065] Particularly preferred PEBA copolymers within the framework of the invention are copolymers comprising blocks of: PA 10 and PEG; PA 10 and PTMG; PA 11 and PEG; PA 11 and PTMG; PA 12 and PEG; PA 12 and PTMG; PA 6.10 and PEG; PA 6.10 and PTMG; PA 6 and PEG; PA 6 and PTMG; PA 6.12 and PEG; PA 6.12 and PTMG.

[0066] The number-average molar mass of the polyamide blocks in the PEBA copolymer is preferably from 400 to 20000 g / mol, more preferably from 500 to 10000 g / mol. In some embodiments, the number-average molar mass of the polyamide blocks in the PEBA copolymer is 400 to 500 g / mol, or 500 to 600 g / mol, or 600 to 1000 g / mol, or 1000 to 1500 g / mol, or 1500 to 2000 g / mol, or 2000 to 2500 g / mol, or 2500 to 3000 g / mol, or 3000 to 3500 g / mol, or 3500 to 4000 g / mol, or 4000 to 5000 g / mol, or 5000 to 6000 g / mol, or 6000 to 7000 g / mol, or 7000 to 8000 g / mol, or 8000 to 9000 g / mol, or 9000 to 10000 g / mol, or 10000 to 11000 g / mol, or 11000 to 12000 g / mol, or 12000 to 13000 g / mol, or from 13000 to 14000 g / mol, or from 14000 to 15000 g / mol, or from 15000 to 16000 g / mol, or from 16000 to 17000 g / mol, or from 17000 to 18000 g / mol, or from 18000 to 19000 g / mol, or from 19000 to 20000 g / mol.

[0067] 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. In modes of

[0068]

[0069]

[0070]

[0071]

[0072] In these applications, the number-average molar mass of the polyether blocks ranges from 100 to 200 g / mol, or from 200 to 500 g / mol, or from 500 to 800 g / mol, or from 800 to 1000 g / mol, or from 1000 to 1500 g / mol, or from 1500 to 2000 g / mol, or from 2000 to 2500 g / mol, or from 2500 to 3000 g / mol, or from 3000 to 3500 g / mol, or from 3500 to 4000 g / mol, or from 4000 to 4500 g / mol, or from 4500 to 5000 g / mol, or from 5000 to 5500 g / mol, or from 5500 to 6000 g / mol. The number-average molar mass is determined by the chain limiter content. It can be calculated using the following relationship: ^X repeating mononomer / H1 chain imitator-^- VIAV1 chain imitator In this formula, nmonomer represents the number of moles of monomer, nchain limiter represents the number of moles of excess diacid limiter, MWmotlfrepeat represents the molar mass of the repeating motif, and MWimitator of chain represents the molar mass of the excess diacid. The number-average molar mass of polyamide blocks and polyether blocks can be measured prior to block copolymerization by gel permeation chromatography (GPC). Advantageously, the quantity of polyamide blocks in the PEBA is at least 10% by weight and preferably at least 20% by weight (relative to the total weight of the PEBA). Even more advantageously, the quantity of polyamide blocks in the PEBA is at least 30% by weight, more preferably at least 40% by weight, and even more preferably at least 50% by weight. The quantity of polyamide blocks in the PEBA may be from 10 to 95% by weight (the quantity of polyether blocks preferably being from 5 to 90% by weight), preferably from 30 to 90% by weight (the quantity of polyether blocks preferably being from 10 to 70% by weight), and preferably from 40 to 85% by weight (the quantity of polyether blocks preferably being from 15 to 60% by weight).More specifically, the quantity of polyamide blocks in PEBA can be from 10 to 30% by weight (the quantity of polyether blocks preferably being 70 to 90% by weight), or from 30 to 40% by weight (the quantity of polyether blocks preferably being 60 to 70% by weight), or from 40 to 50% by weight (the quantity of polyether blocks preferably being 50 to 60% by weight), or from 50 to 60% by weight (the quantity of polyether blocks preferably being 40 to 50% by weight), or from 60 to 70% by weight (the quantity of polyether blocks preferably being 30 to 40% by weight), or from 70 to 80% by weight (the quantity of polyether blocks preferably being 20 to 30% by weight), or from 80 to 95% by weight (the quantity of polyether blocks preferably being 5 to 20% by weight).The quantity of polyamide blocks in PEBA can be determined by proton (1H) NMR in a TFA / CDC13 (1 / 4 v / v) mixture, preferably using a Brucker AM 500 spectrometer, according to the protocol described 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 (signal assignment was performed using Figure 5 of said article). These quantities allow for a foam with lower density, greater flexibility, and improved rebound resilience.

[0073] Preferably, PEBA has an OH function concentration of 0.002 meq / g to 0.2 meq / g, preferably of 0.005 meq / g to 0.1 meq / g, preferably still of 0.01 meq / g to 0.08 meq / g, more preferably of 0.01 meq / g to 0.05 meq / g. In particular, PEBA can have an OH-dependent concentration of 0.002 to 0.005 meq / g, or 0.005 to 0.01 meq / g, or 0.01 to 0.02 meq / g, or 0.02 to 0.03 meq / g, or 0.03 to 0.04 meq / g, or 0.04 to 0.05 meq / g, or 0.05 to 0.06 meq / g, or 0.06 to 0.07 meq / g, or 0.07 to 0.08 meq / g, or 0.08 to 0.09 meq / g, or 0.09 to 0.1 meq / g, or 0.1 to 0.15 meq / g, or 0.15 to 0.2 meq / g. The concentration of OH can be determined by proton (1H) NMR in a TFA / CDC13 (1 / 4 v / v) mixture, preferably using a Brucker AM 500 spectrometer.The 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 and the assignment of the signals is carried out using figure 5 of said article.

[0074] Advantageously, PEBA has a COOH function concentration of 0.002 meq / g to 0.2 meq / g, preferably of 0.005 meq / g to 0.1 meq / g, preferably again of 0.01 meq / g to 0.08 meq / g. PEBA can, for example, have a COOH concentration of 0.002 to 0.005 meq / g, or 0.005 to 0.01 meq / g, or 0.01 to 0.02 meq / g, or 0.02 to 0.03 meq / g, or 0.03 to 0.04 meq / g, or 0.04 to 0.05 meq / g, or 0.05 to 0.06 meq / g, or 0.06 to 0.07 meq / g, or 0.07 to 0.08 meq / g, or 0.08 to 0.09 meq / g, or 0.09 to 0.1 meq / g, or 0.1 to 0.15 meq / g, or 0.15 to 0.2 meq / g. The concentration of COOH functions can be determined by potentiometric analysis according to the following method: a sample of material is dissolved in benzyl alcohol, then the COOH functions of this sample are titrated by potentiometry with a 0.02N tetrabutylammonium hydroxide solution.

[0075] Advantageously, the polyamide-polyether block copolymer has a Shore D hardness greater than or equal to 30. Preferably, the copolymer used in the invention has an instantaneous hardness of 65 Shore A to 80 Shore D, more preferably from 75 Shore A to 65 Shore D, and even more preferably from 80 Shore A to 55 Shore D. Hardness measurements can be carried out according to ISO 7619-1. Thermoplastic polyurethane (TPU)

[0076] Thermoplastic polyurethane is a rigid block and flexible block copolymer.

[0077] Generally speaking, in this text, "rigid block" means a block which exhibits a melting point above 50°C. The presence of a melting point can be determined by differential scanning calorimetry, according to ISO 11357-3 Plastics - Differential scanning calorimetry (DSC) Part 3. A "soft block" is defined as a block with a glass transition temperature (Tg) less than or equal to 0°C. The glass transition temperature can be determined by differential scanning calorimetry, according to ISO 11357-2 Plastics - Differential scanning calorimetry (DSC) Part 2.

[0078] Thermoplastic polyurethanes result from the reaction of at least one polyisocyanate with at least one compound reactive with isocyanate, preferably having two functional groups reactive with isocyanate, more preferably a polyol, and with a chain extender, optionally in the presence of a catalyst. The rigid blocks of TPU are blocks made up of motifs derived from polyisocyanates and chain extenders, while the flexible blocks mainly comprise motifs derived from compounds reactive with isocyanate having a molar mass between 0.5 and 100 kg / mol, preferably polyols.

[0079] The polyisocyanate may be aliphatic, cycloaliphatic, araliphatic, and / or aromatic. Preferably, the polyisocyanate is aliphatic or aromatic. More advantageously, the polyisocyanate is aliphatic. Preferably, the polyisocyanate is a diisocyanate.

[0080] Advantageously, the polyisocyanate is selected from the group consisting of tri-, tetra-, penta-, hexa-, hepta- and / or octamethylene diisocyanate, 2-methylpentamethylene 1,5-diisocyanate, 2-ethylbutylene-1,4-diisocyanate, 1,5-pentamethylene diisocyanate, 1,4-butylene diisocyanate, l-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), 1,4-bis(isocyanatomethyl)cyclohexane, l,3-bis(isocyanatomethyl)cyclohexane (HXDI), 2,4-paraphenylene diisocyanate (PPDI), 2,4-tetramethylenexylene diisocyanate (TMXDI), 4,4'-, 2,4'- and / or 2,2'-dicyclohexylmethane diisocyanate (H12MDI), 1,4-cyclohexane diisocyanate, l-methyl-2,4- and / or l-methyl-2,6-cyclohexane diisocyanate, 2,2'-, 2,4'- and / or 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), 2,4- and / or 2,6-toluene diisocyanate (TDI), diphenylmethane diisocyanate, 3,3'-dimethyldiphenyl diisocyanate, 1,2-Diphenylethane diisocyanate, phenylene diisocyanate, methylene bis(4-cyclohexylisocyanate) (HMDI) and mixtures thereof.

[0081] More preferably, the polyisocyanate is chosen from the group consisting of diphenylmethane diisocyanates (MDI), toluene diisocyanates (TDI), pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), methylene bis (4-cyclohexylisocyanate) (HMDI) and mixtures thereof.

[0082] Even more preferably, the polyisocyanate is 4,4'-MDI (4,4'-diphenylmethane diisocyanate), 1,6-HDI (1,6-hexamethylene diisocyanate), or a mixture thereof. Even more advantageously, the polyisocyanate is 1,6-HDI.

[0083] The compound(s) reactive with isocyanate preferably have an average functionality between 1.8 and 3, more preferably between 1.8 and 2.6, and even more preferably between 1.8 and 2.2. The average functionality of the compound(s) reactive with isocyanate corresponds to the number of isocyanate-reactive functions of the molecules, calculated theoretically for one molecule from a quantity of compounds. Preferably, the compound reactive with isocyanate has, according to a statistical average, a number of active Zerewitinoff hydrogens in the above ranges.

[0084] Preferably, the compound reactive with the isocyanate (preferably a polyol) has a number-average molar mass of 500 to 100,000 g / mol. The compound reactive with the isocyanate may have a number-average molar mass of 500 to 8,000 g / mol, preferably still 700 to 6,000 g / mol, more particularly 800 to 4,000 g / mol. In some embodiments, the compound reacting with the isocyanate has a number-average molar mass of 500 to 600 g / mol, or 600 to 700 g / mol, or 700 to 800 g / mol, or 800 to 1000 g / mol, or 1000 to 1500 g / mol, or 1500 to 2000 g / mol, or 2000 to 2500 g / mol, or 2500 to 3000 g / mol, or 3000 to 3500 g / mol, or 3500 to 4000 g / mol, or 4000 to 5000 g / mol, or 5000 to 6000 g / mol, or 6000 to 7000 g / mol, or 7000 to 8000 g / mol, or from 8000 to 10000 g / mol, or from 10000 to 15000 g / mol, or from 15000 to 20000 g / mol, or from 20000 to 30000 g / mol, or from 30000 to 40,000 g / mol, or from 40,000 to 50,000 g / mol, or from 50,000 to 60,000 g / mol, or from 60,000 to 70,000 g / mol, or from 70,000 to 80,000 g / mol, or from 80,000 to 100,000 g / mol. The mass number average molar can be determined by GPC, preferably according to ISO 16014-1:2012.

[0085] Advantageously, the compound that reacts with the isocyanate has at least one reactive group selected from among the hydroxyl group, the amine group, the thiol group, and the carboxylic acid group. Preferably, the compound that reacts with the isocyanate has at least one hydroxyl reactive group, and more preferably several hydroxyl groups. Thus, particularly advantageously, the compound that reacts with the isocyanate comprises or consists of a polyol.

[0086] Preferably, the polyol is selected from the group consisting of polyester polyols, polyether polyols, polycarbonate diols, polysiloxane diols, polyalkylene diols, and mixtures thereof. More preferably, the polyol is a polyether polyol, a polyester polyol, and / or a polycarbonate diol, so that the flexible blocks of the thermoplastic polyurethane are polyether blocks, polyester blocks, and / or polycarbonate blocks, respectively. Even more preferably, the Flexible blocks of thermoplastic polyurethane are polyether blocks and / or polyester blocks (the polyol being a polyether polyol and / or a polyester polyol).

[0087] Examples of polyester polyols include polycaprolactone polyols and / or copolyesters based on one or more carboxylic acids selected from adipic acid, succinic acid, pentanedioic acid and / or sebacic acid and one or more alcohols selected from 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol and / or polytetrahydrofuran. More specifically, the copolyester may be based on adipic acid and a mixture of 1,2-ethanediol and 1,4-butanediol, or the copolyester may be based on adipic acid, succinic acid, pentanedioic acid, sebacic acid or mixtures thereof, and polytetrahydrofuran (tetramethylene glycol), or the copolyester may be a mixture of these copolyesters.

[0088] As a polyether polyol, polyetherdiols (i.e., aliphatic α,co-dihydroxylated polyoxyalkylene blocks) are preferably used. Preferably, the polyether polyol is a polyetherdiol based on ethylene oxide, propylene oxide, and / or butylene oxide, a block copolymer based on ethylene oxide and propylene oxide, polyethylene glycol, polypropylene glycol, polybutylene glycol, polytetrahydrofuran, polybutane diol, or a mixture thereof.The polyether polyol is preferably a polytetrahydrofuran (flexible blocks of thermoplastic polyurethane are therefore polytetrahydrofuran blocks) and / or a polypropylene glycol (flexible blocks of thermoplastic polyurethane are therefore polypropylene glycol blocks) and / or a polyethylene glycol (flexible blocks of thermoplastic polyurethane are therefore polyethylene glycol blocks), preferably a polytetrahydrofuran having a number-average molar mass of 500 to 15,000 g / mol, preferably 1,000 to 3,000 g / mol. The polyether polyol may be a polyetherdiol, which is the reaction product of ethylene oxide and propylene oxide; the molar ratio of ethylene oxide to propylene oxide is preferably from 0.01 to 100, more preferably from 0.1 to 9, more preferably from 0.25 to 4, more preferably from 0.4 to 2.5, more preferably from 0.6 to 1.5 and it is more preferably 1.

[0089] The polysiloxane diols usable in the invention preferably have a number-average molar mass of 500 to 15,000 g / mol, preferably of 1,000 to 3,000 g / mol. The number-average molar mass can be determined by GPC, preferably according to ISO 16014-1:2012. Advantageously, the polysiloxane diol is a polysiloxane of formula (I):

[0090] [Chem.2] HO-[RO]oR-Si(R')2-[O-Sî(R')2]mO-Si(R')2-R-[OR]P-OH

[0091] wherein R is preferably a C2-C4 alkylene, R' is preferably a C1-C4 alkyl, and each of n, m, and p independently represents an integer preferably from 0 to 50, with m more preferably from 1 to 50, and even more preferably from 2 to 50. Preferably, the polysiloxane has the following formula (II):

[0092] [Chem.3] HO (He)

[0093] in which Me is a methyl group, or the following formula (III):

[0094] [Chem.4] (III)

[0095] The polyalkylene diols usable in the invention are preferably butadiene-based.

[0096] The polycarbonate diols usable in the invention are preferably aliphatic polycarbonate diols. The polycarbonate diol is preferably alkanediol-based. Preferably, it is strictly bifunctional. The preferred polycarbonate diols are those based on butanediol, pentanediol and / or hexanediol, in particular 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methylpentane-(1,5)-diol, or mixtures thereof, more preferably based on 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, or mixtures thereof. In particular, the polycarbonate diol may be a polycarbonate diol based on butanediol and hexanediol, or based on pentanediol and hexanediol, or based on hexanediol, or may be a mixture of two or more of these polycarbonate diols. The polycarbonate diol advantageously has a number-average molar mass of 500 to 4000 g / mol, preferably 650 to 3500 g / mol, more preferably 800 to 3000 g / mol.The number-average molar mass can be determined by GPC, preferably according to ISO 16014-1:2012.

[0097] One or more polyols may be used as a reactive compound with the isocyanate.

[0098] In a particularly preferred manner, the flexible blocks of the TPU are blocks of polytetrahydrofuran, polypropylene glycol and / or polyethylene glycol.

[0099] A chain extender is used for the preparation of thermo- polyurethane plastic, in addition to isocyanate and the compound reactive with isocyanate.

[0100] The chain extender may be aliphatic, araliphatic, aromatic, and / or cycloaliphatic. It advantageously has a number-average molar mass of 50 to 499 g / mol. The number-average molar mass may be determined by GPC, preferably according to ISO 16014-1:2012. The chain extender preferably has two reactive groups with the isocyanate (also called "functional groups"). A single chain extender or a mixture of at least two chain extenders may be used.

[0101] The chain extender is preferably bifunctional. Examples of chain extenders are diamines and alkanediols having from 2 to 10 carbon atoms. In particular, the chain extender may be selected from the group consisting of 1,2-ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanediol, 1,4-dimethanol cyclohexane, neopentyl glycol, hydroquinone bis(beta-hydroxyethyl) ether (HQEE), di-, tri-, tetra-, penta-, hexa-, hepta-, octa-, nona- and / or deca-alkylene glycol, their respective oligomers, polypropylene glycol and mixtures thereof.More preferably, the chain extender is chosen from the group consisting of 1,2-ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and mixtures thereof, and even more preferably it is chosen from 1,3-propanediol, 1,4-butanediol and / or 1,6-hexanediol. Even more preferably, the chain extender is a mixture of 1,4-butanediol and 1,6-hexanediol, more preferably in a molar ratio of 6:1 to 10:1.

[0102] Advantageously, a catalyst is used to synthesize the thermoplastic polyurethane. The catalyst accelerates the reaction between the NCO groups of the polyisocyanate and the reactive compound with the isocyanate (preferably with the hydroxyl groups of the reactive compound with the isocyanate) and with the chain extender.

[0103] The catalyst is preferably a tertiary amine, more preferably chosen from triethylamine, dimethylcyclohexylamine, N-methylmorpholine, N,N'-dimethylpiperazine, 2-(dimethylaminoethoxy)-ethanol and / or diazabicyclo-(2,2,2)-octane. Alternatively, or additionally, the catalyst is an organic metallic compound such as an acid ester of titanium, an iron compound, preferably ferric acetylacetonate, a tin compound, preferably those of carboxylic acids, more preferably tin diacetate, tin dioctoate, tin dilaurate or dialkyl tin salts, preferably dibutyltin diacetate and / or dibutyltin dilaurate, a bismuth carboxylic acid salt, preferably bismuth decanoate, or a mixture thereof.

[0104] More preferably, the catalyst is chosen from the group consisting of the Tin dioctoate, bismuth decanoate, titanium dioxide esters, and mixtures thereof. Preferably, the catalyst is tin dioctoate.

[0105] During the preparation of thermoplastic polyurethane, the molar ratios of the reactive compound with the isocyanate and the chain extender can be varied to adjust the hardness and flow index of the TPU. Specifically, as the proportion of chain extender increases, the hardness and molten viscosity of the TPU increase, while the flow index of the TPU decreases. For the production of flexible TPU, preferably TPU having a Shore A hardness of less than 95, more preferably from 75 to 95, the reactive compound with the isocyanate and the chain extender can be used in a molar ratio of 1:1 to 1:5, preferably from 1:1.5 to 1:4.5, preferably so that the mixture of reactive compound with the isocyanate and chain extender has an equivalent weight of hydroxyl greater than 200, more particularly from 230 to 650, even more preferably from 230 to 500.For the production of a harder TPU, preferably a TPU with a Shore A hardness greater than 98, preferably a Shore D hardness of 55 to 75, the reactive compound with the isocyanate and the chain extender can be used in a molar ratio of 1:5.5 to 1:15, preferably 1:6 to 1:12, preferably so that the mixture of reactive compound with the isocyanate and chain extender has an equivalent weight of hydroxyl of 110 to 200, more preferably 120 to 180.

[0106] Advantageously, to prepare TPU, polyisocyanate, the reactive compound with isocyanate, and the chain extender are reacted, preferably in the presence of a catalyst, in quantities such that the ratio in equivalents of the NCO groups of polyisocyanate to the sum of the hydroxyl groups of the reactive compound with isocyanate and the chain extender is 0.95:1 to 1.10:1, preferably 0.98:1 to 1.08:1, and even more preferably 1:1 to 1.05:1. The catalyst is advantageously present in an amount of 0.0001 to 0.1 parts by weight per 100 parts by weight of the TPU synthesis reagents.

[0107] The TPU preferably has a weight-average molar mass greater than or equal to 10,000 g / mol, preferably greater than or equal to 40,000 g / mol, and more preferably greater than or equal to 60,000 g / mol. Preferably, the weight-average molar mass of the TPU is less than or equal to 80,000 g / mol. In some embodiments, the weight-average molar mass of the TPU is from 10,000 to 25,000 g / mol, or from 25,000 to 40,000 g / mol, or from 40,000 to 50,000 g / mol, or from 50,000 to 60,000 g / mol, or from 60,000 to 70,000 g / mol, or from 70,000 to 80,000 g / mol. Weight-average molar masses can be determined by gel permeation chromatography (GPC).

[0108] The rigid block content in the TPU is preferably less than or equal to 90% by weight and preferably even less than or equal to 80% by weight (relative to the less total TPU). More advantageously, the rigid block content in TPU is 30 to 60% by weight (the flexible block content being 40 to 70% by weight). More specifically, the rigid block content in TPU can be 10 to 20% by weight (the flexible block content being 80 to 90% by weight), or 20 to 30% in weight (the quantity of flexible blocks representing 70 to 80% by weight), or 30 to 40% in weight (the quantity of flexible blocks representing 60 to 70% by weight), or 40 to 50% in weight (the quantity of flexible blocks representing 50 to 60% by weight), or 50 to 60% in weight (the quantity of flexible blocks representing 40 to 50% by weight), or 60 to 70% in weight (the quantity of flexible blocks representing 30 to 40% by weight), or 70 to 80% in weight (the quantity of flexible blocks representing 20 to 30% by weight), or 80 to 90% by weight (the quantity of soft blocks representing 10 to 20% by weight). These quantities allow for a foam with a lower density, greater flexibility, and better rebound resilience. The content of rigid blocks, expressed as a percentage, is defined as follows:

[0109] [(mass fraction of polyisocyanates + mass fraction of chain extender) / (mass fraction of polyisocyanates + mass fraction of chain extender + mass fraction of compounds reactive with the isocyanate)] x 100

[0110] It can be measured by proton NMR in DMSO D6, according to the protocol described in the article: “Reactivity of isocyanates with urethanes: Conditions for al-lophanate formation”, Lapprand et al., Polymer Degradation and Stability, Volume 90, No. 2, 2005, 363-373.

[0111] Advantageously, the TPU is semi-crystalline. Its melting temperature Tf is preferably between 100°C and 230°C, and even more preferably between 120°C and 200°C. The melting temperature can be measured according to ISO 11357-3 Plastics - Differential scanning calorimetry (DSC) Part 3.

[0112] Advantageously, the TPU can be recycled TPU and / or partially or completely bio-based TPU.

[0113] Advantageously, the TPU has a melt flow index (MFI) of 10 to 100 g / 10 min, preferably 25 to 80 g / 10 min, and more preferably 35 to 65 g / 10 min. In particular, the melt flow index of the TPU may be 10 to 25 g / 10 min, or 25 to 35 g / 10 min, or 35 to 45 g / 10 min, or 45 to 55 g / 10 min, or 55 to 65 g / 10 min, or 65 to 80 g / 10 min, or 80 to 100 g / 10 min. The melt flow index is measured at 200°C under a 10 kg load, according to ASTM DI238.

[0114] Preferably, the TPU has a Shore D hardness of 75 or less, more preferably 65 or less. In particular, the TPU used in the invention can have a hardness of 65 Shore A to 70 Shore D, preferably from 75 Shore A to 60 Shore D. Hardness measurements can be carried out according to ISO 7619-1.

[0115] Advantageously, TPU has an OH function concentration of 0.002 meq / g to 0.6 meq / g, preferably of 0.01 meq / g to 0.4 meq / g, preferably still of 0.03 meq / g to 0.2 meq / g. In embodiments, TPU has an OH function concentration of 0.002 to 0.005 meq / g, or 0.005 to 0.01 meq / g, or 0.01 to 0.02 meq / g, or 0.02 to 0.04 meq / g, or 0.04 to 0.06 meq / g, or 0.06 to 0.08 meq / g, or 0.08 to 0.1 meq / g, or 0.1 to 0.2 meq / g, or 0.2 to 0.3 meq / g, or 0.3 to 0.4 meq / g, or 0.4 to 0.5 meq / g, or 0.5 to 0.6 meq / g. The concentration of OH function can be determined by proton NMR in DMSO D6, according to the protocol described in the article below: “Reactivity of isocyanates with urethanes: Conditions for allophanate formation”, Lapprand et al., Polymer Degradation and Stability, Volume 90, No. 2, 2005, 363-373.

[0116] Very advantageously, the TPU is not cross-linked. TPU and PEBA foam

[0117] Advantageously, the amount of polyamide blocks in the foam is at least 15% by weight, preferably at least 20% by weight, preferably still at least 25% by weight, preferably still at least 30% by weight, preferably still at least 35% by weight (relative to the total weight of the foam). The amount of polyamide blocks in the foam can be determined by proton NMR in a TFA / CDC13 (1 / 4 v / v) mixture, preferably using a Brucker AM 500 spectrometer, according to the protocol described 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 (signal assignment being carried out using Figure 5 of said article).

[0118] The amount of rigid blocks of thermoplastic polyurethane in the foam is preferably less than or equal to 50% by weight, preferably less than or equal to 35% by weight, preferably less than or equal to 25% by weight, and preferably less than or equal to 15% by weight, relative to the total weight of the foam. The amount of rigid blocks of thermoplastic polyurethane in the foam can be measured by proton NMR in DMSO D6, according to the protocol described in the article: “Reactivity of isocyanates with urethanes: Conditions for allophanate formation”, Lapprand et al., Polymer Degradation and Stability, Volume 90, No. 2, 2005, 363-373.

[0119] The quantities indicated above allow for a lower density, greater flexibility and better rebound resilience of the foam.

[0120] The foam according to the invention preferably comprises 40 to 95% by weight of PEBA and 5 to 60% by weight of TPU, more preferably 50 to 90% by weight of PEBA and 10 to 50% by weight of TPU, relative to the total weight of the foam. More advantageously, the foam according to the invention comprises 55 to 80% by weight of PEBA and 20 to 45% by weight of TPU, more preferably 60 to 75% by weight of TPU. PEBA weight, and 25 to 40% TPU weight, relative to the total foam weight. In some embodiments, the foam comprises 40 to 45% by weight of PEBA and 55 to 60% by weight of TPU, or 45 to 50% by weight of PEBA and 55 to 50% by weight of TPU, or 50 to 55% by weight of PEBA and 45 to 50% by weight of TPU, or 55 to 60% by weight of PEBA and 40 to 45% by weight of TPU, or 60 to 65% by weight of PEBA and 35 to 40% by weight of TPU, or 65 to 70% by weight of PEBA and 30 to 35% by weight of TPU, or 70 to 75% by weight of PEBA and 25 to 30% by weight of TPU, or 75 to 80% by weight of PEBA and 20 to 25% by weight of TPU, or 80 to 85% by weight of PEBA, and 15 to 20% by weight of TPU, or 85 to 90% by weight of PEBA, and 10 to 15% by weight of TPU, or 90 to 95% by weight of PEBA, and 5 to 10% by weight of TPU, relative to the total weight of the foam.

[0121] Advantageously, the foam contains a total soft block content of the PEBA(s) and TPU(s) of between 30 and 80% by weight, preferably between 40% and 75% by weight, relative to the total weight of the foam. The total soft block content can be determined by nuclear magnetic resonance (NMR), as described above. In particular, these soft blocks include the polyether blocks of the PEBA and the soft blocks of the TPU.

[0122] The foam according to the invention has an OH function concentration of 0.002 meq / g to 0.2 meq / g, preferably of 0.005 meq / g to 0.1 meq / g, preferably again of 0.01 meq / g to 0.08 meq / g. In particular, the foam according to the invention can have an OH concentration of 0.002 to 0.005 meq / g, or 0.005 to 0.01 meq / g, or 0.01 to 0.02 meq / g, or 0.02 to 0.03 meq / g, or 0.03 to 0.04 meq / g, or 0.04 to 0.05 meq / g, or 0.05 to 0.06 meq / g, or 0.06 to 0.07 meq / g, or 0.07 to 0.08 meq / g, or 0.08 to 0.09 meq / g, or 0.09 to 0.1 meq / g, or 0.1 to 0.15 meq / g, or 0.15 to 0.2 meq / g.

[0123] Advantageously, the foam according to the invention has a COOH function concentration of 0.001 meq / g to 0.2 meq / g, preferably of 0.005 meq / g to 0.1 meq / g, preferably again of 0.01 meq / g to 0.08 meq / g. In particular, the foam according to the invention can have a COOH concentration of 0.001 to 0.005 meq / g, or 0.005 to 0.01 meq / g, or 0.01 to 0.02 meq / g, or 0.02 to 0.03 meq / g, or 0.03 to 0.04 meq / g, or 0.04 to 0.05 meq / g, or 0.05 to 0.06 meq / g, or 0.06 to 0.07 meq / g, or 0.07 to 0.08 meq / g, or 0.08 to 0.09 meq / g, or 0.09 to 0.1 meq / g, or 0.1 to 0.15 meq / g, or 0.15 to 0.2 meq / g.

[0124] The COOH concentration of the foam can be determined by potentiometric analysis according to the following method: a sample of foam is dissolved in benzyl alcohol, then the COOH groups of this sample are titrated by potentiometry with a 0.02N tetrabutylammonium hydroxide solution. OH function concentration can be determined by proton NMR in a TFA / CDC13 (1 / 4 v / v) mixture, preferably using a Brucker AM 500 spectrometer, as described in the article "Synthesis and characterization of poly(copolyethers-block-polyamides) - II. Characterization and properties of the multiblock copolymers", Maréchal et al., Polymer, Volume 41, 2000, 3561-3580 (signal assignment being carried out using figure 5 of said article).

[0125] Advantageously, the TPU and PEBA foam according to the invention comprises at least a portion of the total polyamide and polyether block copolymer covalently bonded to thermoplastic polyurethane by a urethane function.

[0126] Preferably, the portion of the polyamide and polyether block copolymer covalently bonded to thermoplastic polyurethane by a urethane function represents 10% or less by weight, preferably 5% or less by weight, preferably 3% or less by weight, more preferably 2% or less by weight, of the amount of the polyamide and polyether block copolymer.

[0127] The foam according to the invention may consist essentially of, or consist of, at least one polyamide-polyether block copolymer and at least one thermoplastic polyurethane, and optionally a blowing agent, in the foam matrix and / or in the pores of the foam, particularly if it is a closed-pore foam. The foam matrix may consist essentially of, or consist of, at least one TPU and at least one PEBA. The foam may also include degradation products of a blowing agent (particularly in its matrix), especially when a chemical blowing agent has been used to form the foam.

[0128] Alternatively, the foam may comprise one or more additives, for example, ethylene-vinyl acetate or EVA copolymers (e.g., those marketed under the name Evatane® by SK Chemical), or ethylene-acrylate copolymers, or ethylene-alkyl(meth)acrylate copolymers, for example, those marketed under the name Lotryl® by SK Chemical. These additives may allow adjustment of the foamed part's hardness, appearance, and comfort.Other suitable additives for the invention include pigments (such as TiO2 and other compatible colored pigments), adhesion promoters (to improve the adhesion of the foam to other materials), fillers (e.g., calcium carbonate, barium sulfate and / or silicon dioxide), nucleating agents (particularly in pure or concentrated form, e.g., CaCO3, ZnO, SiO2, or combinations of two or more of these), rubbers (to improve rubbery elasticity, such as natural rubber, SBR, polybutadiene and / or ethylene propylene ter-polymers), stabilizers (e.g., antioxidants, UV absorbers and / or flame retardants), additives to improve processability (“processing aids”) (e.g., stearic acid), anti-. oxidants, including phenolic antioxidants such as IRGANOX from Ciba Geigy Inc. Additives may be present in a content of 0 to 30% by weight, preferably 0.1 to 20% by weight, preferably still 0.2 to 10% by weight, relative to the total weight of the foam.

[0129] The foam according to the invention preferably has a density less than or equal to 800 kg / m3, more preferably less than or equal to 600 kg / m3, more preferably less than or equal to 400 kg / m3, even more preferably less than or equal to 300 kg / m3, and particularly preferably less than or equal to 230 kg / m3. It may, for example, have a density of 25 to 600 kg / m3, and more particularly preferably of 50 to 300 kg / m3. The density of the foam can range from 25 to 100 kg / m³, or from 100 to 200 kg / m³, or from 200 to 250 kg / m³, or from 250 to 300 kg / m³, or from 300 to 400 kg / m³, or from 400 to 500 kg / m³, or from 500 to 600 kg / m³, or from 600 to 800 kg / m³. Density can be controlled by adjusting the parameters of the manufacturing process. Density can be measured at 23°C according to ISO 1183-1.

[0130] Preferably, the foam according to the invention has an Asker C hardness of 20 to 90, preferably from 25 to 70. In particular, the Asker C hardness of the foam can be from 20 to 25, or from 25 to 30, or from 30 to 40, or from 40 to 50, or from 50 to 60, or from 60 to 70, or from 70 to 80, or from 80 to 90. The Asker C hardness can be determined at 23°C, after 15 seconds, according to ISO 7619-1.

[0131] Preferably, the foam has a rebound resilience greater than or equal to 50%, preferably greater than or equal to 55%. The rebound resilience is measured according to ISO 8307:2007 but using an 18.8 g ball.

[0132] Preferably, this foam exhibits a compression set according to ISO 7214 of less than or equal to 65%, preferably less than or equal to 50%, for example less than or equal to 45%, or less than or equal to 40%, or less than or equal to 35%. The compression set is measured after a 25% compression applied for 70 hours at 23°C followed by a 30-minute relaxation.

[0133] Preferably, this foam also exhibits excellent fatigue resistance and damping properties.

[0134] Preferably, this foam also exhibits good resistance to tearing and crack propagation.

[0135] The foam according to the invention can be used to manufacture sports equipment, such as soles for sports shoes, ski boots, midsoles, insoles, or functional components of soles, in the form of inserts in different parts of the sole (heel or arch) plantar for example), or components of shoe uppers in the form of reinforcements or inserts in the structure of the shoe upper, in the form of protections.

[0136] It can also be used to manufacture balls, sports gloves (for example football gloves), golf ball components, rackets, protective elements (vests, internal elements of helmets, shells...).

[0137] The foam according to the invention exhibits interesting shock-absorbing, vibration-damping, and noise-dampening properties, combined with haptic properties suitable for capital goods. It can therefore also be used for the manufacture of railway track bases, or various parts in the automotive, transportation, electrical and electronic equipment, construction, or manufacturing industries.

[0138] According to advantageous embodiments, the foam objects according to the invention can be easily recycled, for example by melting them in an extruder equipped with a degassing outlet (optionally after cutting them into pieces). Preparing the mousse

[0139] The foam according to the invention can be prepared by mixing a polymer composition comprising at least one TPU and at least one PEBA with an expanding agent (and optionally with one or more additives), and then carrying out a foaming step.

[0140] The expanding agent may be a chemical or physical agent, or may also consist of any type of hollow object or any type of expandable microsphere. Preferably, it is a physical agent, such as, for example, nitrogen or carbon dioxide, or a hydrocarbon, chlorofluorocarbon, hydrochlorocarbon, hydrofluorocarbon, or hydrochlorofluorocarbon (saturated or unsaturated), or a mixture thereof. For example, butane or pentane may be used. Preferably, it may also be a chemical agent, such as, for example, azodicarbonamide or mixtures based on citric acid and sodium bicarbonate (NaHCO3) (such as the product in the Hydrocerol® range from Clariant).

[0141] In some embodiments, a physical blowing agent is used and mixed with the molten polymer composition. The physical blowing agent may be in liquid or supercritical form and is then converted to a gaseous phase during the foaming step. Foaming may be caused by a pressure drop, for example, resulting from the exit of an extruder.

[0142] Advantageously, the mixture of the polymer composition and the blowing agent is injected into a mold and foaming is carried out in the mold. Foaming can be induced by opening the mold, by underdosing, by applying a Gas counter-pressure, using a breathable mold or a mold equipped with a Variotherm® system, allows for the direct production of three-dimensional foamed objects with complex geometries. These techniques are also relatively simple to implement, especially compared to certain foam particle melting processes: filling the mold with polymer foam granules and then melting the particles to ensure the mechanical strength of the parts without destroying the foam structure are complex operations.

[0143] In alternative embodiments, the polymer composition is used to create a preform. This preform can be prepared by compression molding, extrusion, injection molding, lamination, or 3D printing. Preferably, the preform is produced by extrusion or injection molding. This preform, in its solid state, is brought into contact with a physical blowing agent in gaseous or supercritical form. The physical blowing agent impregnates the solid preform, preferably by applying overpressure. Preferably, the foaming is carried out in an autoclave, preferably at a temperature slightly below the melting point of the polymer composition. Preferably, the pressure inside the autoclave is maintained between 0.20 and 50 MPa during the foaming process. Advantageously, the foaming of the preform is contained within a mold.

[0144] Other usable foaming techniques include batch foaming, extrusion foaming, such as single-screw or twin-screw extrusion foaming, and microwave foaming.

[0145] In a particularly preferred manner, the polymer composition comprising TPU and PEBA is prepared prior to its mixing with the blowing agent. Preferably, the polymer composition is an alloy of TPU and PEBA. By "alloy" is meant a homogeneous mixture (macroscopically, i.e., visible to the naked eye).

[0146] According to a first advantageous embodiment, the polymer composition can be prepared by a process comprising a step of mixing the polyamide-polyether block copolymer and the thermoplastic polyurethane in the molten state. Such a preparation process allows, under certain temperature and mixing time conditions, a reaction to take place between the hydroxyl groups of a portion of the polyamide-polyether block copolymer and the isocyanate groups resulting from the dissociation of a portion of the methane groups of the thermoplastic polyurethane into isocyanate and alcohol under the effect of heat, thereby improving the compatibility between the polyamide-polyether block copolymer and the thermoplastic polyurethane.

[0147] The mixing of TPU and PEBA can take place in any device for mixing, kneading or extruding molten plastics known to humankind. The mixing mechanism may include an internal mixer, a roller mixer, an extruder (such as a single-screw extruder or a twin-screw extruder with counter- or co-rotating screws), a co-mixer (such as a continuous co-mixer), or a stirred reactor. Preferably, the mixing takes place in an extruder or co-mixer, more preferably in an extruder, and even more preferably in a twin-screw extruder.

[0148] Preferably, the mixing is carried out at a temperature greater than or equal to 160°C, preferably from 160 to 300°C, and even more preferably from 180 to 260°C. These temperature ranges allow for an optimal reaction between the polyamide and polyether block copolymer and the thermoplastic polyurethane, and therefore better compatibility of the two polymers.

[0149] Advantageously, the mixing is carried out for a period of 30 seconds to 15 minutes, preferably from 40 seconds to 10 minutes. Preferably, the mixing is carried out under agitation. These mixing conditions allow for an optimal reaction between the polyamide-polyether block copolymer and the thermoplastic polyurethane, and therefore better compatibility of the two polymers.

[0150] The step of mixing TPU with PEBA may include mixing the polyamide and polyether block copolymer and thermoplastic polyurethane, in the molten state, with additives.

[0151] According to another advantageous embodiment, the polymer composition can be prepared by introducing the polyamide-polyether block copolymer during the synthesis of the thermoplastic polyurethane. In such a preparation process, the polyamide-polyether block copolymer is used as a reactive compound with the isocyanate (as described above in the section "Thermoplastic Polyurethane (TPU)"), optionally in addition to another reactive compound with the isocyanate, preferably a polyol as described above.

[0152] Thus, the preparation process may include the steps of: • introduction into a reactor of the precursors of thermoplastic polyurethane (i.e. at least one polyisocyanate, at least one chain extender, and optionally at least one compound reactive with the isocyanate); • introduction into the reactor of the copolymer with polyamide and polyether blocks; and • synthesis of thermoplastic polyurethane in the reactor in the presence of the copolymer with polyamide blocks and polyether blocks, so as to obtain the polymer composition.

[0153] Such a preparation process allows the reaction of the hydroxyl groups of a portion of the polyamide and polyether block copolymer with the isocyanate groups of a portion of the polyisocyanate during the synthesis of the thermoplastic polyurethane, leading to the formation of covalent bonds between the block copolymer polyamides and polyether block copolymers and thermoplastic polyurethane, which improves the compatibility between polyamide and polyether block copolymers and thermoplastic polyurethane.

[0154] The steps of introducing the thermoplastic polyurethane precursors and the polyamide-polyether block copolymer can be simultaneous or carried out in any order. A catalyst, in particular such as described above, can also be introduced into the reactor.

[0155] The reactor may be a batch reactor, a stirred reactor, a static mixer, an internal mixer, a roller mixer, an extruder, such as a single-screw extruder or a twin-screw counter- or co-rotating extruder, a continuous co-mixer, or a combination thereof. Preferably, the reactor is an extruder, more preferably a twin-screw extruder.

[0156] Preferably, the thermoplastic polyurethane synthesis step (in the presence of the polyamide-polyether block copolymer) is carried out at a temperature of 160°C or higher, preferably from 160 to 300°C, and even more preferably from 180 to 270°C. These temperature ranges allow for an optimal reaction between the polyamide-polyether block copolymer and the thermoplastic polyurethane, and therefore better compatibility between the two polymers.

[0157] One or more additives may be introduced into the reactor (at any time during the process) and mixed with the thermoplastic polyurethane and the polyamide and polyether block copolymer in the reactor.

[0158] Regardless of the variant used, the preparation process may include a step of shaping the TPU and PEBA mixture into granules or powder. When the mixture is in powder form, it is preferably first formed into granules and then the granules are ground into powder. Any type of mill can be used, such as a hammer mill, a pin mill, an attrition disc mill, or an impact classifier mill.

[0159] In the processes for preparing the polymer composition described above, all the characteristics described above in relation to the polyamide and polyether block copolymer and the thermoplastic polyurethane (in particular their nature, quantity, concentration in OH, COOH and / or amine function...) can be applied similarly to the polyamide and polyether block copolymer and the thermoplastic polyurethane used in these processes. Examples

[0160] The following examples illustrate the invention without limiting it.

[0161] The following polymers were used: • PEBA 1: PEBA copolymer comprising blocks of PA 11 of mass number-average molar mass 600 g / mol and PTMG blocks with a number-average molar mass of 1000 g / mol and a hardness of 35 Shore D • PEBA 2: PEBA copolymer comprising PA 11 blocks with a number average molar mass of 1000 g / mol and PTMG blocks with a number average molar mass of 1000 g / mol, with a hardness of 40 Shore D. • TPU: Rigid block TPU based on 4,4'-MDI and 1,4-BDO (1,4-butanediol) and flexible block polyethers (PTMG), with a hardness of 85 Shore A.

[0162] A polymer composition was prepared by mixing 65% by weight of PEBA 2 and 35% by weight of TPU using a ZSK 18 mm twin-screw extruder (Coperion). The barrel temperature was set at 210°C and the screw speed was 280 rpm with a throughput of 8 kg / h. The composition was then dried under reduced pressure at 80°C to achieve a moisture content of less than 0.04%. The hydroxyl group concentration in this composition is 0.036 meq / g, measured by proton NMR in a TFA / CDC13 mixture (1 / 4 v / v) using a Brucker AM 500 spectrometer as described in the article "Synthesis and characterization of poly(copolyethers-block-polyamides) - Characterization and properties of the multiblock copolymers", Maréchal et al., Polymer, Volume 41, 2000, 3561-3580. Elongational rheometry of materials

[0163] An extensional viscosity fixture (or EVF) analysis was performed for the polymer composition as well as for PEBA 2 and TPU alone.

[0164] To this end, films were prepared as follows: 6 g of product were placed in the center of a 1 mm thick frame, itself placed between two 2 mm thick metal plates. The assembly was placed between the platens of a press (CAR VER press) heated to 180°C. The platens were in contact with the assembly, without pressure, for 5 min. Then, a pressure of 10 MPa was applied for 2 min. After this compression time, the assembly was removed from the press, placed in ambient air under a 12.5 kg load, and cooled for 30 min. The two 2 mm plates allow for slow cooling and proper crystallization of the film. Films 700 to 800 µm thick, without texture or bubbles, were obtained. The films were not incubated and were analyzed as is the following day.

[0165] Elongational tests were carried out on the films under the following operating conditions: • Rheometer: ARES G2 • Geometry: EVF module (“Extensional Viscosity Fixture”) • Temperature: 180°C or 200°C • Rotation speed: 1 s • Sample dimensions: 700 µm thick and 10 mm wide • Atmosphere: Nitrogen sweep • Setup time: 1 min

[0166] The test temperature was set at 180°C for the polymer composition and PEBA alone and at 200°C for TPU alone so that each sample would be completely melted.

[0167] When the elongational viscosity increases with strain without reaching a plateau, the tested material exhibits a behavior called "strain hardening." The viscosity of the molten polymer material increases with the level of strain applied to it. In other words, the greater the strain applied to the polymer material, the more it resists this deformation. This effect induces better foamability of the material because the polymer material is then able to limit the growth of foam cells during the foaming process. This phenomenon allows the formation of finer and more homogeneous cells, and therefore the production of higher-performance foams.

[0168] The results are presented in [Fig.1].

[0169] The elongational viscosities of PEBA alone and TPU alone reach a high-strain plateau. The absence of strain hardening thus limits the foaming capacity of these products. Foams formed with these products are therefore limited in terms of density and / or mechanical properties.

[0170] Conversely, the polymer composition has a viscosity that increases continuously with applied deformation. The phenomenon of strain hardening is clearly observed in this alloy, suggesting improved foaming of the polymer composition. Foam evaluation

[0171] Foams were then prepared: • Foam 1 (comparative): made from PEBA 1 alone; • Foam 2 (comparative): made from PEBA 2 alone; • Foam 3 (according to the invention): manufactured from the polymer composition.

[0172] The 15 mm thick foams were prepared using an Arburg Allrounder 520A 150T injection molding machine with a Trexel IL series physical blowing agent injection system. This machine uses Mucell® technology with partial mold opening (core-back process). The operating parameters are as follows: - Sheath temperature: 250°C - Mold geometry (mm): 200 x 100 x 1.6 mm - Injection speed: 120 cmVs - Holding time before opening the mold: 1 s - Holding pressure: 25.0 MPa - Cooling time: 240 s - Mold temperature: 15°C - Mold opening length: 15 mm

[0173] The blowing agent used is nitrogen (N2) introduced at a concentration of 0.7% by weight.

[0174] The properties of the following foams were evaluated: • Density: according to ISO 1183-1, at 23°C, using the vertical thrust method in water; 5 repetitions were performed. • Density: characterizes the homogeneity of the foam and corresponds to the difference in density of the foamed part between the point closest to the injection point and the point furthest from the injection point; the lower this value, the more homogeneous the foam. • Rebound resilience: according to ISO 8307 except that an 18.8 ga ball was used (an 18.8 g steel ball with a diameter of 16 mm is dropped from a height of 500 mm onto a foam sample, the rebound resilience then corresponds to the percentage of energy returned to the ball, or percentage of the initial height reached by the ball at the rebound); 5 repetitions were carried out. • Asker C hardness (15 s): according to ISO 7619-1, measured with a Hildebrand Asker C durometer. • Compression test: according to ISO 3386-1, measured using a ZWICK compression machine. Foam samples measuring 50 x 50 x 15 mm are subjected to four compression cycles up to 70% deformation, with a displacement rate of 100 mm / min at a temperature of 23°C. The measurements at the 4th compression cycle are representative of the intrinsic behavior of the foam, and the stresses corresponding to 25%, 40%, and 50% deformation are recorded.

[0175] The results are presented in the following table:

[0176] [Tables] Foam 1 (comparative) Foam 2 (comparative) Foam 3 (invention) Density (kg / m3) Average 0.297 0.250 0.216 Standard deviation 0.002 0.015 0.004 Density (kg / m3) 0.031 0.025 0.004 Rebound strength (%) Average 59 59 58 Standard deviation 1 2 2 Asker C hardness (15 s) 71 70 58 Compressive stress at different deformations (kPa) 25% ND 99 88 40% ND 199 165 50% ND 316 262

[0177] ND = not determined

[0178] The foam according to the invention has a lower and more homogeneous density than the comparative foams prepared from PEBA alone. Furthermore, the foam according to the invention exhibits greater flexibility, as illustrated by its Asker C hardness, and lower compressive stresses than the comparative PEBA foams, all while exhibiting similar rebound resilience. In conclusion, while PEBA-only foams do not allow for simultaneously achieving low densities and low hardness, the foam according to the invention is lighter and more flexible while maintaining equivalent rebound performance.

Claims

Demands

1. Polymer foam comprising: • at least one thermoplastic polyurethane, and • at least one polyamide block and poly ether block copolymer, said foam having an OH function concentration of 0.002 meq / g to 0.2 meq / g as measured by proton NMR in a TFA / CDC13 (1 / 4 v / v) mixture.

2. Foam according to claim 1, wherein at least a portion of the total polyamide and polyether block copolymer is covalently linked to a thermoplastic polyurethane molecule by a urethane function, preferably an amount less than or equal to 10% by weight, more preferably less than or equal to 5% by weight, of the polyamide and polyether block copolymer is covalently linked to a thermoplastic polyurethane molecule by a urethane function.

3. Foam according to claim 1 or 2, wherein at least one polyamide block and polyether block copolymer has an OH function concentration, as measured by proton NMR in a TFA / CDC13 (1 / 4 v / v) mixture, of 0.003 to 0.15 meq / g, preferably of 0.005 meq / g to 0.1 meq / g, preferably again of 0.01 meq / g to 0.08 meq / g.

4. Foam according to any one of claims 1 to 3, wherein at least one polyamide block and polyether block copolymer has a COOH function concentration of 0.002 meq / g to 0.2 meq / g, preferably 0.005 meq / g to 0.1 meq / g, as measured by potentiometric titration in benzyl alcohol using a 0.02N tetrabutylammonium hydroxide solution.

5. Foam according to any one of claims 1 to 4, wherein the hot melt flow index MFI of thermoplastic polyurethane measured according to ASTM DI238 at 200°C under a 10 kg load is 10 to 100 g / 10 min, preferably 25 to 80 g / 10 min, more preferably 35 to 65 g / 10 min.

6. Foam according to any one of claims 1 to 5, wherein the amount of polyamide blocks, as measured by proton NMR in a TFA / CDC13 (1 / 4 v / v) mixture, is at least 15% by weight, of preference of at least 25% by weight, relative to the total weight of the foam.

7. Foam according to any one of claims 1 to 6, wherein the polyamide block and polyether block copolymer comprises at least 30 wt%, preferably at least 40 wt%, of polyamide blocks, relative to the total weight of the copolymer, as measured by proton NMR in a TFA / CDC13 (1 / 4 v / v) mixture.

8. Foam according to any one of claims 1 to 7, wherein at least one thermoplastic polyurethane is a rigid block and soft block copolymer, the rigid block content in the thermoplastic polyurethane, as measured by proton NMR in DMSO D6, being less than or equal to 90% by weight, preferably still less than or equal to 80% by weight, more preferably from 30 to 60% by weight.

9. Foam according to any one of claims 1 to 8, comprising, relative to the total weight of the foam: • 20 to 45% by weight, preferably 25 to 40% by weight, of at least one thermoplastic polyurethane, and • 55 to 80% by weight, preferably 60 to 75% by weight, of at least one copolymer with polyamide blocks and polyether blocks.

10. Foam according to any one of claims 1 to 9, wherein at least one thermoplastic polyurethane is a rigid block and flexible block copolymer, wherein: • the flexible blocks are selected from polyether blocks, polyester blocks, polycarbonate blocks and a combination thereof, preferably the flexible blocks are selected from polyether blocks, polyester blocks, and a combination thereof, and are more preferably blocks of polytetrahydrofuran, polypropylene glycol and / or polyethylene glycol; and / or • the rigid blocks comprise motifs from 4,4'-diphenylmethane diisocyanate and / or 1,6-hexamethylene diisocyanate and, preferably, motifs from at least one chain extender selected from 1,3-propanediol, 1,4-butanediol and / or 1,6-hexanediol.

11. Foam according to any one of claims 1 to 10, wherein the polyamide blocks of the polyamide block and polyether block copolymer are blocks of polyamide 11, polyamide 12, polyamide 10, polyamide 6, polyamide 6.10, polyamide 6.12, polyamide 6.13, polyamide 10.9, polyamide 10.10, polyamide 10.12 and / or polyamide 12.9, preferably of polyamide 11, polyamide 12, polyamide 6, polyamide 6.12, polyamide 6.13, polyamide 10.9 and / or polyamide 12.9; and / or the polyether blocks of the polyamide and polyether block copolymer are polyethylene glycol and / or polypropylene glycol and / or polytetrahydrofuran blocks.

12. Foam according to any one of claims 1 to 11, having a density, as measured at 23°C according to ISO 1183-1, less than or equal to 800 kg / m3, preferably less than or equal to 300 kg / m3, more preferably less than or equal to 230 kg / m3.

13. Foam according to any one of claims 1 to 12, having an Asker C hardness, as measured at 23°C according to ISO 7619-1, of 20 to 90, preferably 25 to 70.

14. A method for manufacturing a foam according to any one of claims 1 to 13, comprising the following steps: • supplying a polymer composition comprising at least one thermoplastic polyurethane and at least one polyamide and polyether block copolymer; • mixing said polymer composition with a blowing agent; and • foaming the mixture of polymer composition and blowing agent.

15. A method according to claim 14, wherein the expanding agent is mixed with the polymer composition in the molten state, the foaming of the mixture being preferably carried out in a mold.

16. A method according to claim 14 wherein the expanding agent is a physical expanding agent and is mixed with the polymer composition in the form of a solid preform, the foaming of the mixture being preferably carried out in an autoclave.

17. A method according to any one of claims 14 to 16, wherein the step of supply of the polymer composition includes: • mixing, preferably in an extruder, of at least one thermoplastic polyurethane and at least one molten polyamide and polyether block copolymer, so as to obtain the polymer composition; and • optionally, shaping the polymer composition into granules or powder.

18. A process according to any one of claims 14 to 16, wherein the step of supplying the polymer composition comprises: • introducing into a reactor, preferably an extruder, precursors of at least one thermoplastic polyurethane; • introducing into the reactor at least one copolymer of polyamide and polyether blocks; • synthesizing the thermoplastic polyurethane in the reactor in the presence of the copolymer of polyamide and polyether blocks, so as to obtain the polymer composition; and • optionally, shaping the polymer composition into granules or powder.

19. Article made of a foam according to any one of claims 1 to 13 or comprising at least one element made of a foam according to any one of claims 1 to 13, preferably selected from sports shoe soles, balls, gloves, personal protective equipment, rail soles, automotive parts, construction parts and electrical and electronic equipment parts.

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