Thermoplastic polyurethane and polyamide foam

Abstract

The invention relates to a polymer foam comprising at least one thermoplastic polyurethane and at least one polyamide comprising amine chain ends, wherein the polyamide is the reaction product of one or more monomers selected from amino acids or aminocarboxylic acids, lactams and monomers derived from the reaction between an aliphatic diamine and a dicarboxylic acid. The invention also relates to a method for preparing such a foam, and to an item comprising such a foam.

Description

[0001] Description Title: Thermoplastic polyurethane and polyamide foam

[0002] Field of invention

[0003] The present invention relates to polymeric foams, comprising a thermoplastic polyurethane and an amine-end-terminated polyamide, and methods of preparing the same.

[0004] Technical background

[0005] 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 particularly for sports (vests, interior parts of helmets, shells, etc.).

[0006] Such applications require a set of specific physical properties that ensure rebound properties, low permanent deformation in compression, and the ability to withstand repeated impacts without deforming and returning to the initial shape.

[0007] 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 polyesterester, and the second thermoplastic elastomer is in particular a thermoplastic polyurethane, a thermoplastic polyetheramide, a polyetherester or a polyesterester or a thermoplastic styrene-butadiene copolymer.

[0008] There is a need to provide polymer foams having a fine and homogeneous cell structure, having low density, good rebound resilience and satisfactory flexibility and tear resistance.

[0009] Summary of the invention

[0010] The invention relates firstly to a polymer foam comprising, relative to the total weight of the foam, from 10 to 99% by weight, preferably from 15 to 89% by weight, of at least one thermoplastic polyurethane, - from 1 to 40% by weight, preferably from 1 to 30% by weight, of at least one polyamide comprising amine chain ends, as detected by potentiometric assay in metacresol using a 0.02N perchloric acid solution, in which the polyamide is the reaction product of one or more monomers chosen from amino acids or aminocarboxylic acids, lactams and monomers resulting from the reaction between an aliphatic diamine and a dicarboxylic acid.

[0011] In embodiments, the foam comprises, relative to the total weight of the foam, from 60 to 99% by weight of at least one thermoplastic polyurethane and from 1 to 40% by weight of at least one polyamide comprising amine chain ends.

[0012] In embodiments, at least a portion of the total polyamide is covalently linked to a thermoplastic polyurethane molecule through a urea functionality.

[0013] In embodiments, the urea functional concentration, as measured by 13C NMR in DMSO D6, is from 0.001 meq / g to 0.1 meq / g, more preferably from 0.003 meq / g to 0.08 meq / g, more preferably from 0.005 meq / g to 0.05 meq / g.

[0014] In embodiments, the polyamide has an NH2 amine function concentration, as measured by potentiometric assay in metacresol using a 0.02N perchloric acid solution, of 0.01 meq / g to 2.0 meq / g, preferably 0.02 to 1.5 meq / g, more preferably 0.02 to 1 meq / g, even more preferably 0.02 meq / g to 0.4 meq / g.

[0015] In embodiments, the at least one thermoplastic polyurethane is a rigid block and soft block copolymer, wherein:

[0016] - the flexible blocks are chosen from polyether blocks, polyester blocks, polycarbonate blocks and a combination thereof, preferably the flexible blocks are chosen from polyether blocks, polyester blocks, and a combination thereof, and are more preferably blocks of polytetrahydrofuran, polypropylene glycol and / or polyethylene glycol; and / or

[0017] - the rigid blocks comprise units derived from 4,4'-diphenylmethane diisocyanate and / or 1,6-hexamethylene diisocyanate and, preferably, units derived from at least one chain extender chosen from 1,3-propanediol, 1,4-butanediol and / or 1,6-hexanediol. In embodiments, the polyamide comprising amine chain ends is chosen from the group consisting of polyamide 11, polyamide 12, polyamide 10, polyamide 6, polyamide 6.10, polyamide 6.6, polyamide 10.10, polyamide 10.12, polyamide 6.13, polyamide 10.9, polyamide 12.9 and combinations thereof.

[0018] In embodiments, the foam further comprises at least one polyamide block and polyether block copolymer.

[0019] In embodiments, the foam comprises, relative to the total weight of the foam: from 10 to 99% by weight, preferably from 15 to 89% by weight, of at least one thermoplastic polyurethane, from 1 to 40% by weight, preferably from 1 to 30% by weight, of at least one polyamide comprising amine chain ends, and from 0 to 89% by weight, preferably from 10 to 70% by weight, of at least one copolymer with polyamide blocks and polyether blocks.

[0020] 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 / CDCIs mixture (1 / 4 v / v).

[0021] In embodiments, the polyamide blocks of the polyamide block and polyether block copolymer are selected from polyamide 6, polyamide 6.10, polyamide 6.12, polyamide 11, polyamide 10, polyamide 12, polyamide 6.13, polyamide 10.9 and / or polyamide 12.9 blocks; and / or the polyether blocks of the polyamide block and polyether block copolymer are polyethylene glycol and / or polypropylene glycol and / or polytetrahydrofuran blocks.

[0022] In embodiments, the polyamide comprising amine chain ends has a number average molar mass of 1000 to 60000 g / mol, preferably of 2000 to 40000 g / mol, even more preferably of 3000 to 20000 g / mol.

[0023] In embodiments, the foam has a density, as measured at 23°C according to ISO 1183-1, of less than or equal to 800 kg / m 3 , preferably less than or equal to 400 kg / m 3, more preferably less than or equal to 300 kg / m 3 , even more preferably less than or equal to 230 kg / m 3 .

[0024] The invention also relates to a method for manufacturing a foam as described above, comprising the following steps: - providing a polymer composition comprising at least one thermoplastic polyurethane and at least one polyamide comprising amine chain ends, and where appropriate at least one copolymer with polyamide blocks and polyether blocks;

[0025] - mixing said polymer composition with a blowing agent; and

[0026] - foaming of the mixture of polymer composition and blowing agent.

[0027] In embodiments, the blowing agent is mixed with the polymer composition in the molten state, the foaming of the mixture preferably being carried out in a mold.

[0028] In embodiments, the blowing agent is a physical blowing agent and is mixed with the polymer composition in the form of a solid preform, with foaming of the mixture preferably carried out in an autoclave.

[0029] 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 the soles of sports shoes, balls, gloves, personal protective equipment, soles for rails, automobile parts, construction parts and parts of electrical and electronic equipment.

[0030] The present invention makes it possible to meet the need expressed above. More particularly, it provides a regular, homogeneous, low-density polymer foam, capable of exhibiting improved flexibility and good mechanical properties, in particular good tear resistance and good abrasion resistance, while maintaining high rebound resilience and relatively low compression set.

[0031] This is accomplished by using, for foam formation, a blend of a thermoplastic polyurethane (TPU) and a polyamide (PA) having amine chain ends (NH2), as defined above.

[0032] According to certain advantageous embodiments, covalent bonds are formed between at least a portion of the polyamide comprising amine chain ends and at least a portion of the thermoplastic polyurethane, and more particularly between the amine functions of the polyamide and the urethane functions of the thermoplastic polyurethane or the isocyanate functions present in the precursors of the thermoplastic polyurethane. This reaction between at least a portion of the polyamide comprising amine chain ends and at least a portion of the thermoplastic polyurethane allows better compatibility between these polymers.This results in an improvement in the foamability of the alloys, and therefore an improvement in the structure (finer and more homogeneous cellular structure, lower density) and properties (in particular, higher rebound resilience, lower deformation and compression set, higher flexibility) of the foams obtained from these alloys.

[0033] Detailed description

[0034] The invention is now described in more detail and in a non-limiting manner in the following description.

[0035] Unless otherwise stated, all percentages are by mass.

[0036] In this text, the quantities indicated for a given species may apply to this species according to all its definitions (as mentioned in this text), including the more restricted definitions.

[0037] The invention relates firstly to a foam comprising at least one polyamide comprising amine chain ends and at least one thermoplastic polyurethane.

[0038] The presence of amine chain ends in polyamide can be detected by potentiometric determination using the following method: a sample of material is dissolved in metacresol at 80°C, then the NH2 functions of this sample are determined by potentiometry using a 0.02N perchloric acid solution.

[0039] Polyamide (PA) with amine chain ends

[0040] The polyamide with amine chain ends can be a homopolyamide and / or a copolyamide.

[0041] Polyamide means the polymerization products of one or more monomers chosen from:

[0042] - amino acid or aminocarboxylic acid monomers, and preferably alpha, omega-aminocarboxylic acids, preferably having from 6 to 14 carbon atoms;

[0043] - lactam-type monomers preferably having from 3 to 18 carbon atoms on the main cycle and which may be substituted; - “diamine-diacid” type monomers resulting from the reaction between an aliphatic diamine preferably having from 2 to 48 carbon atoms, more preferably from 2 to 20 carbon atoms, and a dicarboxylic acid preferably having from 4 to 48 carbon atoms, more preferably from 4 to 20 carbon atoms; and

[0044] - their mixtures, with monomers with different carbon numbers in the case of mixtures between an amino acid type monomer and a lactam type monomer.

[0045] The term "monomer" in the present description of polyamides must be taken in the sense of "repeating unit". Indeed, the case where a repeating unit of the polyamide is made up of the association of a diacid with a diamine is particular. It is considered that it is the association of a diamine and a diacid, that is to say the diamine.diacid pair (in equimolar quantity), which corresponds to the monomer. This is explained by the fact that individually, the diacid or the diamine is only a structural unit, which is not sufficient on its own to polymerize.

[0046] For the purposes of the present invention, the polyamide with amine chain ends consists solely of polyamide. In particular, it does not comprise a block of another type, such as, for example, a polyether block, a polyester block, a polysiloxane block, polyolefin blocks, or a polycarbonate block. More particularly, the polyamide with amine chain ends is not a copolymer with polyamide blocks and polyether blocks. The foam according to the invention may, however, comprise a polyamide, with or without amine chain ends, comprising a block other than a polyamide block, provided that it also comprises a polyamide with amine chain ends consisting solely of polyamide.

[0047] When the polyamide is a homopolyamide, it is the polymerization product of a single monomer. When the polyamide is a copolyamide, it is the polymerization product of at least two different monomers.

[0048] Advantageously, three types of polyamides can be used.

[0049] According to a first type, the polyamides come from the condensation of a dicarboxylic acid, in particular those having from 4 to 48 carbon atoms, preferably those having from 4 to 20 carbon atoms, more preferably from 6 to 18 carbon atoms, and an aliphatic or aromatic diamine, in particular those having from 2 to 48 carbon atoms, preferably those having from 2 to 20 atoms, more preferably from 5 to 14 carbon atoms.

[0050] Examples of dicarboxylic acids include 1,4-cyclohexyldicarboxylic acid, butanedioic, adipic, azelaic, suberic, sebacic, dodecanedicarboxylic, octadecanedicarboxylic acids, terephthalic and isophthalic acids, and also dimerized fatty acids.

[0051] Examples of diamines include ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 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-cyclohexyl-methane (PACM), isophoronediamine (IPDA), 2,6-bis-(aminomethyl)-norbornane (BAMN) and piperazine (Pip).

[0052] Advantageously, polyamides PA 4.12, PA 4.14, PA 4.18, PA 5.10, PA 5.12, PA 5.14, PA 5.16, PA 5.18, 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 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, conventionally.

[0053] According to a second type, the polyamides result from the condensation of one or more α,α-aminocarboxylic acids and / or one or more lactams having from 3 to 18 carbon atoms, preferably from 6 to 14 carbon atoms in the presence of a dicarboxylic acid having from 2 to 48 carbon atoms, preferably from 4 to 20 carbon atoms, or a diamine. Examples of lactams include caprolactam, oenantholactam and lauryllactam. Examples of α,α-aminocarboxylic acids include aminocaproic, amino-7-heptanoic, amino-10-decanoic, amino-11-undecanoic and amino-12-dodecanoic acids.

[0054] Advantageously, the polyamides of the second type are 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 from the amino acid residues or lactam residues.

[0055] According to a third type, polyamides result from the condensation of at least one α,α-aminocarboxylic acid (or a lactam), at least one diamine and at least one dicarboxylic acid.

[0056] In this case, the PA polyamides are prepared by polycondensation: - of the linear or aromatic aliphatic diamine(s) having X carbon atoms;

[0057] - dicarboxylic acid(s) having Y carbon atoms; and

[0058] - of the comonomer(s) {Z}, chosen from lactams and α,α-aminocarboxylic acids having Z carbon atoms and equimolar mixtures of at least one diamine having X1 carbon atoms and at least one dicarboxylic acid having Y1 carbon atoms, (X1, Y1) being different from (X, Y),

[0059] - said comonomer(s) {Z} being introduced in a weight proportion advantageously ranging up to 50%, preferably up to 20%, even more advantageously up to 10% relative to all of the polyamide precursor monomers;

[0060] - in the presence of a chain limiter chosen from dicarboxylic acids.

[0061] Advantageously, the dicarboxylic acid having Y carbon atoms is used as chain limiter, which is introduced in excess relative to the stoichiometry of the diamine(s).

[0062] According to a variant of this third type, the polyamides result from the condensation of at least two α,α-aminocarboxylic acids or at least two lactams having from 6 to 12 carbon atoms or a lactam and an aminocarboxylic acid not having the same number of carbon atoms in the optional presence of a chain limiter. Examples of aliphatic α,α-aminocarboxylic acids include aminocaproic, amino-7-heptanoic, amino-10-decanoic, amino-11-undecanoic and amino-12-dodecanoic acids. Examples of lactams include caprolactam, oenantholactam and lauryllactam. Examples of aliphatic diamines include pentamethylenediamine, hexamethylenediamine, dodecamethylenediamine, and trimethylhexamethylenediamine. Examples of cycloaliphatic diacids include 1,4-cyclohexyldicarboxylic acid.Examples of aliphatic diacids include butanedioic, adipic, azelaic, suberic, sebacic, dodecanedicarboxylic acids, polyoxyalkylene α,α-diacids, 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 acid); they preferably have a dimer content of at least 98%; they are preferably hydrogenated; they are preferably a mixture comprising from 0 to 15% by weight of C18 monoacids, from 60 to 99% by weight of C36 diacids, and from 0.2 to 35% by weight of C54 or higher triacids or polyacids; These include, 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-cyclohexyl-methane (PACM). Other commonly used diamines include isophoronediamine (IPDA), 2,6-bis-(aminomethyl)-norbornane (BAMN) and piperazine.

[0063] Examples of polyamides of the third type include the following:

[0064] - PA 6.6 / 6, where 6.6 denotes hexamethylenediamine units condensed with adipic acid and 6 denotes units resulting from the condensation of caprolactam;

[0065] - 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 units resulting from the condensation of aminoundecanoic acid and 12 denotes units resulting from the condensation of lauryllactam.

[0066] 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.

[0067] Advantageously, the polyamide used in the invention comprises or consists of a polyamide 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 comprises, or consists of, polyamide blocks 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 polyamide blocks 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, even more preferably polyamide blocks PA 6, PA 11, PA 12, PA 6.12, PA 6.13, PA 10.9, PA 12.9, or mixtures or copolymers thereof.

[0068] Preferably, the amide bonds of the polyamide are free of tertiary amides (i.e., amides in which the amine is a tertiary amine). More preferably, all of the amide bonds of the polyamide are secondary amides (i.e., the amines of the amide bonds are secondary amines).

[0069] The polyamide comprising amine chain ends advantageously has a number-average molar mass of 1000 to 60000 g / mol, preferably of 2000 to 40000 g / mol, very advantageously of 3000 to 20000 g / mol. In embodiments, the amine-ended polyamide may have a number average molar mass of 1000 to 2000 g / mol, or 2000 to 3000 g / mol, or 3000 to 5000 g / mol, or 5000 to 10000 g / mol, or 10000 to 15000 g / mol, or 15000 to 20000 g / mol, or 20000 to 25000 g / mol, or 25000 to 30000 g / mol, or 30000 to 35000 g / mol, or 35000 to 40000 g / mol, or 40000 to 45000 g / mol, or 45000 to 50000 g / mol, or from 50,000 to 55,000 g / mol, or from 55,000 to 60,000 g / mol.

[0070] The number-average molar mass is determined by the chain limiter content. It can be calculated using the following relationship:

[0071] Mn = Hmonomer X MWrepeat motif / H chain limiter + MWchain limiter

[0072] In this formula, nmonomer represents the number of moles of monomer, nichain limiter represents the number of moles of excess diacid limiter, MWrepeat unit represents the molar mass of the repeat unit, and MWchain limiter represents the molar mass of the excess diacid.

[0073] The number average molar mass of polyamide can be measured by gel permeation chromatography (GPC).

[0074] Preferably, at least 50% by weight of the polyamide comprising amine chain ends (relative to the total weight of the polyamide comprising amine chain ends) has a molar mass less than or equal to 20,000 g / mol, more preferably from 50 to 80% by weight of the polyamide comprising amine chain ends has a molar mass less than or equal to 20,000 g / mol. These amounts of polyamide can be determined by GPC. These ranges make it possible to obtain a lower density of the foam.

[0075] The polyamide comprising amine chain ends may be monofunctional (i.e. it comprises a single amine chain end per PA molecule) or it may be difunctional (i.e. it comprises two amine chain ends per PA molecule); it is preferably monofunctional.

[0076] The polyamide preferably has an amine function (NH2) concentration of 0.01 meq / g to 2.0 meq / g, preferably 0.04 meq / g to 1.5 meq / g, more preferably 0.1 to 1.5 meg / eq, more preferably 0.35 to 1.5 meq / g. In particular, the polyamide with amine chain ends may have a concentration as a function of NH2 of 0.01 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, or 0.6 to 0.7 meq / g, or 0.7 to 0.8 meq / g, or 0.8 to 0.9 meq / g, or 0.9 to 1.0 meq / g, or 1 .0 to 1.1 meq / g, or 1.1 to 1.2 meq / g, or 1.2 to 1.3 meq / g, or 1.3 to 1.4 meq / g, or 1.4 to 1.5 meq / g, or 1.5 to 1.6 meq / g, or 1.6 to 1.7 meq / g, or 1.7 to 1.8 meq / g, or 1.8 to 1.9 meq / g, or 1.9 to 2.0 meq / g.The NH2 function concentration can be measured using a potentiometric assay according to the following method: a foam sample is dissolved in metacresol at 80°C, then the NH2 functions of this sample are assayed potentiometrically with a 0.02N perchloric acid solution.

[0077] The polyamide comprising amine chain ends may have a COOH concentration of 0.002 meq / g to 0.2 meq / g, preferably 0.005 meq / g to 0.1 meq / g, more preferably 0.01 meq / g to 0.08 meq / g. In particular, the polyamide may 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 using the following method: a sample of material is dissolved in benzyl alcohol, then the COOH functions of this sample are determined by potentiometry using a 0.02N tetrabutylammonium hydroxide solution.

[0078] The above concentrations (in amine and COOH functions) correspond to the concentrations of the polyamides comprising amine chain ends taken in their entirety (i.e., when the foam comprises several polyamides comprising amine chain ends, all of these polyamides are considered). The polyamides comprising amine chain ends can be prepared by condensation of the polyamide precursors (i.e., monomers as described above). Advantageously, the addition of a chain-limiting diamine makes it possible to increase the concentration at the end of the amine chain in the polyamide. The molar ratio of the NH2 amine functions to the COOH functions of all the monomers loaded into the reactor during the synthesis of the polyamide makes it possible to determine the concentration at the end of the amine chain of the polyamide.

[0079] The molar ratio of NH2 amine functions to COOH functions is advantageously 0.7 to 1.3, preferably 0.85 to 1.25.

[0080] The polyamide comprising amine chain ends is advantageously semi-crystalline. Preferably, it has a melting enthalpy greater than 5 J / g. The melting enthalpy can be measured by differential scanning calorimetry (DSC) analysis according to ISO 11357-3 Plastics - Differential scanning calorimetry (DSC) Part 3.

[0081] Thermoplastic polyurethane is a copolymer of rigid and soft blocks.

[0082] Generally, in this text, a "rigid block" means a block that has 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" means 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.

[0083] Thermoplastic polyurethanes result from the reaction of at least one polyisocyanate with at least one isocyanate-reactive compound, preferably having two isocyanate-reactive functional groups, more preferably a polyol, and with a chain extender, optionally in the presence of a catalyst. The rigid blocks of the TPU are blocks consisting of units derived from polyisocyanates and chain extenders, while the flexible blocks mainly comprise units derived from isocyanate-reactive compounds having a molar mass of between 0.5 and 100 kg / mol, preferably polyols. 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.

[0084] Advantageously, the polyisocyanate is selected from the group consisting of tri-, tetra-, penta-, hexa-, hepta- and / or octamethylene diisocyanate, 2-methyl-pentamethylene 1,5-diisocyanate, 2-ethyl-butylene-1,4-diisocyanate, 1,5-pentamethylene diisocyanate, 1,4-butylene diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (isophorone diisocyanate, IPDI), 1,4-bis(isocyanatomethyl)cyclohexane, 1,3-bis(isocyanatomethyl)cyclohexane (HXDI), 2,4-paraphenylene diisocyanate (PPDI), 2,4-tetramethylene xylene diisocyanate (TMXDI), 4,4'-, 2,4'- and / or 2,2'-dicyclohexylmethane diisocyanate (H12 MDI), 1,4-cyclohexane diisocyanate, 1-methyl-2,4- and / or 1-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'-dimethyl-diphenyl diisocyanate, 1,2-diphenylethane diisocyanate, phenylene diisocyanate, methylene bis(4-cyclohexyl isocyanate) (HMDI) and mixtures thereof.,

[0085] More preferably, the polyisocyanate is selected from the group consisting of diphenylmethane diisocyanates (MDI), toluene diisocyanates (TDI), pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), methylene bis (4-cyclohexyl isocyanate) (HMDI) and mixtures thereof.

[0086] 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.

[0087] The isocyanate-reactive compound(s) preferably have an average functionality of between 1.8 and 3, more preferably between 1.8 and 2.6, more preferably between 1.8 and 2.2. The average functionality of the isocyanate-reactive compound(s) corresponds to the number of isocyanate-reactive functions of the molecules, calculated theoretically for a molecule from a quantity of compounds. Preferably, the isocyanate-reactive compound has, according to a statistical average, a Zerewitinoff active hydrogen number in the above ranges. Preferably, the isocyanate-reactive compound (preferably a polyol) has a number-average molar mass of 500 to 100,000 g / mol. The isocyanate-reactive compound may have a number-average molar mass of 500 to 8000 g / mol, more preferably of 700 to 6000 g / mol, more particularly of 800 to 4000 g / mol.In embodiments, the isocyanate-reactive compound 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.

[0088] 10000 to 15000 g / mol, or 15000 to 20000 g / mol, or 20000 to 30000 g / mol, or 30000 to 40000 g / mol, or 40000 to 50000 g / mol, or 50000 to 60000 g / mol, or 60000 to 70000 g / mol, or 70000 to 80000 g / mol, or 80000 to 100000 g / mol. The number average molar mass can be determined by GPC, preferably according to ISO 16014-1:2012.

[0089] Advantageously, the isocyanate-reactive compound has at least one reactive group selected from hydroxyl group, amine group, thiol group and carboxylic acid group. Preferably, the isocyanate-reactive compound has at least one hydroxyl reactive group, more preferably several hydroxyl groups. Thus, particularly advantageously, the isocyanate-reactive compound comprises or consists of a polyol.

[0090] 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, such that the flexible blocks of the thermoplastic polyurethane are polyether blocks, polyester blocks, and / or polycarbonate blocks, respectively. More preferably, the flexible blocks of the thermoplastic polyurethane are polyether blocks and / or polyester blocks (the polyol being a polyether polyol and / or a polyester polyol).

[0091] As polyester polyol, mention may be made of polycaprolactone polyols and / or copolyesters based on one or more carboxylic acids chosen from adipic acid, succinic acid, pentanedioic acid and / or sebacic acid and one or more alcohols chosen 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 particularly, 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.

[0092] As polyether polyol, polyether diols (i.e., aliphatic α,α-dihydroxylated polyoxyalkylene blocks) are preferably used. Preferably, the polyether polyol is a polyether diol based on ethylene oxide, propylene oxide, and / or butylene oxide, a block copolymer based on ethylene oxide and propylene oxide, a polyethylene glycol, a polypropylene glycol, a polybutylene glycol, a polytetrahydrofuran, a polybutane diol, or a mixture thereof.The polyether polyol is preferably a polytetrahydrofuran (soft blocks of the thermoplastic polyurethane therefore being polytetrahydrofuran blocks) and / or a polypropylene glycol (soft blocks of the thermoplastic polyurethane therefore being polypropylene glycol blocks) and / or a polyethylene glycol (soft blocks of the thermoplastic polyurethane therefore being polyethylene glycol blocks), preferably a polytetrahydrofuran having a number average molar mass of 500 to 15000 g / mol, preferably of 1000 to 3000 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 0.01 to 100, more preferably 0.1 to 9, more preferably 0.25 to 4, more preferably 0.4 to 2.5, more preferably 0.6 to 1.5 and it is more preferably 1.

[0093] The polysiloxane diols usable in the invention preferably have a number-average molar mass of 500 to 15000 g / mol, preferably of 1000 to 3000 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): [Chem 1]

[0094] HO-[RO]nR-Si(R')2-[O-Si(R')2] m -O-Si(R')2-R-[OR] P -OH wherein R is preferably C2-C4 alkylene, R' is preferably C1-C4 alkyl and each of n, m and p independently represents an integer preferably between 0 and 50, m being more preferably from 1 to 50, even more preferably from 2 to 50. Preferably, the polysiloxane has the following formula (II): [Chem 2] in which Me is a methyl group, or the following formula (III):

[0095] [Chem 3]

[0096] The polyalkylene diols which can be used in the invention are preferably based on butadiene.

[0097] The polycarbonate diols that can be used in the invention are preferably aliphatic polycarbonate diols. The polycarbonate diol is preferably based on alkanediol. 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 of 650 to 3500 g / mol, more preferably of 800 to 3000 g / mol.The number average molar mass can be determined by GPC, preferably according to ISO 16014-1:2012.

[0098] One or more polyols may be used as the isocyanate-reactive compound.

[0099] Particularly preferably, the flexible TPU blocks are blocks of polytetrahydrofuran, polypropylene glycol and / or polyethylene glycol.

[0100] A chain extender is used for the preparation of thermoplastic polyurethane, in addition to isocyanate and isocyanate-reactive compound.

[0101] 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 isocyanate-reactive groups (also called "functional groups"). A single chain extender or a mixture of two or more chain extenders may be used.

[0102] The chain extender is preferably bifunctional. Examples of chain extenders are diamines and alkanediols having 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 selected 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 more preferably it is selected 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.

[0103] Advantageously, a catalyst is used to synthesize the thermoplastic polyurethane. The catalyst accelerates the reaction between the NCO groups of the polyisocyanate and the isocyanate-reactive compound (preferably with the hydroxyl groups of the isocyanate-reactive compound) and with the chain extender.

[0104] The catalyst is preferably a tertiary amine, more preferably selected 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 metal compound such as a titanium acid ester, 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. More preferably, the catalyst is selected from the group consisting of tin dioctoate, bismuth decanoate, titanium acid esters and mixtures thereof.More preferably, the catalyst is tin dioctoate.

[0105] When preparing thermoplastic polyurethane, the molar ratios of the isocyanate-reactive compound and the chain extender can be varied to adjust the hardness and melt flow rate of the TPU. Indeed, as the proportion of chain extender increases, the hardness and melt viscosity of the TPU increase while the melt flow rate of the TPU decreases. For the production of soft TPU, preferably TPU having a Shore A hardness of less than 95, more preferably 75 to 95, the isocyanate-reactive compound and the chain extender may be used in a molar ratio of 1:1 to 1:5, preferably 1:1.5 to 1:4.5, preferably such that the mixture of isocyanate-reactive compound and chain extender has a hydroxyl equivalent weight of greater than 200, more preferably 230 to 650, even more preferably 230 to 500.For the production of a harder TPU, preferably a TPU having a Shore A hardness greater than 98, preferably a Shore D hardness of 55 to 75, the isocyanate-reactive compound and the chain extender may be used in a molar ratio of 1:5.5 to 1:15, preferably 1:6 to 1:12, preferably such that the mixture of isocyanate-reactive compound and chain extender has a hydroxyl equivalent weight of 110 to 200, more preferably 120 to 180.

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

[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 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 content of rigid blocks in the TPU is preferably less than or equal to 90% by weight and more preferably less than or equal to 80% by weight (relative to the total mass of the TPU). More advantageously, the content of rigid blocks in the TPU is from 30 to 60% by weight (the amount of flexible blocks being from 40 to 70% by weight).More particularly, the content of rigid blocks in the TPU may be 10 to 20% by weight (the amount of soft blocks being 80 to 90% by weight), or 20 to 30% by weight (the amount of soft blocks being 70 to 80% by weight), or 30 to 40% by weight (the amount of soft blocks being 60 to 70% by weight), or 40 to 50% by weight (the amount of soft blocks being 50 to 60% by weight), or 50 to 60% by weight (the amount of soft blocks being 40 to 50% by weight), or 60 to 70% by weight (the amount of soft blocks being 30 to 40% by weight), or 70 to 80% by weight (the amount of soft blocks being 20 to 30% by weight). weight), or 80 to 90% by weight (the amount of soft blocks being 10 to 20% by weight). The content of hard 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 isocyanate-reactive compounds)] 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 allophanate 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 Tm is preferably between 100°C and 230°C, 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 a recycled TPU and / or a partially or completely bio-sourced TPU.

[0113] Advantageously, the TPU has a melt flow index (or MFI) of 10 to 100 g / 10 min, preferably 25 to 80 g / 10 min, 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 load of 10 kg, according to standard ASTM D1238.

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

[0115] Advantageously, the TPU has a concentration as an OH function of 0.002 meq / g to 0.6 meq / g, preferably of 0.01 meq / g to 0.4 meq / g, more preferably of 0.03 meq / g to 0.2 meq / g. In embodiments, the TPU has 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 0.04 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 OH function concentration 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 crosslinked.

[0117] The foam according to the invention may further comprise a copolymer with polyamide blocks and polyether blocks.

[0118] The presence of a polyamide block and polyether block copolymer in the foam allows for greater flexibility and better elasticity of the foam.

[0119] PEBAs result from the polycondensation of polyamide blocks (rigid or hard blocks) with reactive ends with polyether blocks (flexible or soft blocks) with reactive ends, such as, among others, polycondensation:

[0120] 1) polyamide blocks with diamine chain ends with polyoxyalkylene blocks with dicarboxylic chain ends;

[0121] 2) polyamide blocks with dicarboxylic chain ends with polyoxyalkylene blocks with diamine chain ends, obtained for example by cyanoethylation and hydrogenation of aliphatic α,α-dihydroxylated polyoxyalkylene blocks called polyetherdiols; 3) polyamide blocks with dicarboxylic chain ends with polyetherdiols, the products obtained being, in this particular case, polyetheresteramides.

[0122] Polyamide blocks with dicarboxylic 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.

[0123] The polyamide blocks of PEBA (i.e., the nature of the polyamide) may be such as the polyamides described in the previous section, in relation to the polyamide comprising amine chain ends (whether the polyamide blocks of PEBA come from polyamide blocks with diamine chain ends or with dicarboxylic chain ends). In particular, three types of polyamide blocks corresponding to the three types of polyamides described above may advantageously be used.

[0124] More particularly, the polyamide blocks of the copolymer used in the invention may comprise 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.

[0125] Preferably, the polyamide blocks of the copolymer comprise polyamide blocks PA 6, PA 10, PA 11, PA 12, PA 6.10, PA 6.12, PA 10.10, PA 10.12, or mixtures or copolymers thereof, more preferably polyamide blocks PA 6, PA 11, PA 12, PA 6.12, or mixtures or copolymers thereof.

[0126] Polyether blocks are made up of alkylene oxide units.

[0127] The polyether blocks may in particular be PEG (polyethylene glycol) blocks, i.e., consisting of ethylene oxide units, and / or PPG (propylene glycol) blocks, i.e., consisting of propylene oxide units, and / or PO3G (polytrimethylene glycol) blocks, i.e., consisting of polytrimethylene glycol ether units, and / or PTMG (polytetramethylene glycol) blocks, i.e., consisting of tetramethylene glycol units, also called polytetrahydrofuran. Preferably, the polyether blocks of PEBA are blocks of polyethylene glycol and / or polypropylene glycol and / or polytetrahydrofuran. The copolymers may comprise several types of polyethers in their chain, the copolyethers being able to be block or random.

[0128] 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.

[0129] Polyether blocks can also be made up of ethoxylated primary amines. Examples of ethoxylated primary amines include products of formula: [Chem 4]

[0130] H — (OCF CH^ — N — (CH2CH2O — H

[0131] (CH2

[0132] CH3 in which m and n are integers between 1 and 20 and x an integer between 8 and 18. These products are, for example, commercially available under the brand NORAMOX® from the company CECA and under the brand GENAMIN® from the company CLARIANT.

[0133] The flexible polyether blocks may comprise polyoxyalkylene blocks with NH2 chain ends, such blocks being obtainable by cyanoacetylation of aliphatic α,α-dihydroxylated polyoxyalkylene blocks called polyetherdiols. More particularly, the commercial products Jeffamine or Elastamine may be used (for example Jeffamine® D400, D2000, ED 2003, XTJ 542, commercial products from Huntsman, also described in documents JP 2004346274, JP 2004352794 and EP 1482011).

[0134] Polyetherdiol blocks are either used as such and copolycondensed with rigid blocks with carboxylic ends, or aminated to be transformed into polyetherdiamines and condensed with rigid blocks with carboxylic ends.

[0135] The general method for the two-step preparation of PEBA copolymers having ester bonds between the PA blocks and the PE blocks is known and is described, for example, in document FR 2846332. The general method for the preparation of PEBA copolymers having amide bonds between the PA blocks and the PE blocks is known and described, for example, in document EP 1482011. The polyether blocks can also be mixed with polyamide precursors and a diacid chain limiter to prepare the polymers with polyamide blocks and polyether blocks having statistically distributed units (one-step process).

[0136] Of course, the designation PEBA in the present description of the invention relates to PEBAX® marketed by Arkema, to Vestamid® marketed by Evonik®, to Grilamid® marketed by EMS, as well as to Pelestat® type PEBA marketed by Sanyo or to any other PEBA from other suppliers.

[0137] The PEBAs that can be used 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 the present description, provided that these blocks comprise at least one polyamide block and one polyether block. In addition, the PEBAs that can be used 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.

[0138] For example, the copolymer may be a segmented block copolymer comprising three different types of blocks (or "triblock"), which results 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.

[0139] Particularly preferred PEBA copolymers in the context of the invention are copolymers comprising blocks: 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.

[0140] The number-average molar mass of the polyamide blocks in the PEBA copolymer is preferably from 400 to 20,000 g / mol, more preferably from 500 to 10,000 g / mol. In embodiments, the number average molar mass of the polyamide blocks in the PEBA copolymer is from 400 to 500 g / mol, or 500 to 600 g / mol, or from 600 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 5000 g / mol, or from 5000 to 6000 g / mol, or from 6000 to 7000 g / mol, or from 7000 to 8000 g / mol, or from 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 13000 to 14000 g / mol, or 14000 to 15000 g / mol, or 15000 to 16000 g / mol, or 16000 to 17000 g / mol, or 17000 to 18000 g / mol, or 18000 to 19000 g / mol, or 19000 to 20000 g / mol.

[0141] 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 embodiments, the number average molar mass of the polyether blocks is 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.

[0142] The number average molar mass can be calculated according to the relationship:

[0143] Mn = Hmonomer X MWrepeat motif / Hchain limiter + MWchain limiter

[0144] In this formula, nmonomer represents the number of moles of monomer, nichain limiter represents the number of moles of excess diacid limiter, MWrepeat unit represents the molar mass of the repeat unit, and MWchain limiter represents the molar mass of the excess diacid.

[0145] The number-average molar mass of polyamide blocks and polyether blocks can be measured prior to copolymerization of the blocks by gel permeation chromatography (GPC).

[0146] Advantageously, the amount 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 amount of polyamide blocks in the PEBA is at least 30% by weight, more preferably at least 40% by weight, even more preferably at least 50% by weight. The amount of polyamide blocks in the PEBA may be from 10 to 95% by weight (the amount of polyether blocks preferably being from 5 to 90% by weight), preferably from 30 to 90% by weight (the amount of polyether blocks preferably being from 10 to 70% by weight), more preferably from 40 to 85% by weight (the amount of polyether blocks preferably being from 15 to 60% by weight).More particularly, the amount of polyamide blocks in the PEBA may be from 10 to 30% by weight (the amount of polyether blocks preferably being from 70 to 90% by weight), or from 30 to 40% by weight (the amount of polyether blocks preferably being from 60 to 70% by weight), or from 40 to 50% by weight (the amount of polyether blocks preferably being from 50 to 60% by weight), or from 50 to 60% by weight (the amount of polyether blocks preferably being from 40 to 50% by weight), or from 60 to 70% by weight (the amount of polyether blocks preferably being from 30 to 40% by weight), or from 70 to 80% by weight (the amount of polyether blocks preferably being from 20 to 30% by weight), or from 80 at 95% by weight (the amount of polyether blocks preferably being 5 to 20% by weight).

[0147] Advantageously, the copolymer with polyamide blocks and polyether blocks 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 of 75 Shore A to 65 Shore D, more preferably of 80 Shore A to 55 Shore D. The hardness measurements can be carried out according to the ISO 7619-1 standard.

[0148] The PEBA may have an OH-dependent concentration of 0.002 meq / g to 0.2 meq / g, preferably 0.005 meq / g to 0.1 meq / g, more preferably 0.01 meq / g to 0.08 meq / g and / or a COOH-dependent concentration of 0.002 meq / g to 0.2 meq / g, preferably 0.005 meq / g to 0.1 meq / g, more preferably 0.01 meq / g to 0.08 meq / g.In particular, the PEBA may 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, and / or 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 function 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 determined by potentiometry by a 0.02N tetrabutylammonium hydroxide solution. The concentration of OH function can be determined by proton NMR (1 H) in a TFA / CDCIs mixture (1 / 4 v / v), 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.

[0149] PEBA may have a concentration as a function of Nhh of 0.01 meq / g to 1 meq / g, preferably of 0.02 meq / g to 0.4 meq / g. PEBA can have a concentration depending on Nhh of 0.01 to 0.015 meq / g, or 0.015 to 0.02 meq / g, or 0.02 to 0.025 meq / g, or 0.025 to 0.03 meq / g, or 0.03 to 0.035 meq / g, or 0.035 to 0.04 meq / g, or 0.04 to 0.045 meq / g, or 0.045 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 0.2 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, or 0.6 to 0.7 meq / g, or 0.7 to 0.8 meq / g, or 0.8 to 0.9 meq / g, or 0.9 to 1 meq / g.The NH2 function concentration can be measured using a potentiometric assay according to the following method: a foam sample is dissolved in metacresol at 80°C, then the NH2 functions of this sample are assayed potentiometrically with a 0.02N perchloric acid solution.

[0150] TPU and PA foam

[0151] The foam according to the invention comprises at least one PA and at least one TPU and optionally at least one PEBA.

[0152] Preferably, the amount of polyamide comprising amine chain ends in the foam is less than or equal to 40% by weight, preferably less than or equal to 30% by weight.

[0153] More preferably, the foam according to the invention comprises from 1 to 40% by weight of at least one polyamide comprising amine chain ends and from 60 to 99% by weight of at least one thermoplastic polyurethane, preferably from 1 to 30% by weight of at least one polyamide comprising amine chain ends and from 70 to 99% by weight of at least one thermoplastic polyurethane, preferably from 1 to 25% by weight of at least one polyamide comprising amine chain ends and from 75 to 99% by weight of at least one thermoplastic polyurethane, more preferably from 1.5 to 25% by weight of at least one polyamide with amine chain ends, and from 75 to 98.5% by weight of at least one thermoplastic polyurethane, even more preferably from 2 to 20% by weight of at least one polyamide comprising amine chain ends amines and from 80 to 98% by weight of at least one thermoplastic polyurethane,relative to the total weight of polyamide including amine chain ends and thermoplastic polyurethane. When polyamide and TPU are present in the above ranges, the foam thus formed has an optimum in terms of low density and high flexibility. In embodiments, the foam comprises from 1 to 5% by weight of at least one polyamide comprising amine chain ends, and from 95 to 99% by weight of at least one thermoplastic polyurethane, or from 5 to 10% by weight of at least one polyamide comprising amine chain ends, and from 90 to 95% by weight of at least one thermoplastic polyurethane, or from 10 to 15% by weight of at least one polyamide comprising amine chain ends, and from 85 to 90% by weight of at least one thermoplastic polyurethane, or from 15 to 20% by weight of at least one polyamide comprising amine chain ends, and from 80 to 85% by weight of at least one thermoplastic polyurethane,or from 20 to 25% by weight of at least one polyamide comprising amine chain ends, and from 75 to 80% by weight of at least one thermoplastic polyurethane, or from 25 to 30% by weight of at least one polyamide comprising amine chain ends, and from 70 to 75% by weight of at least one thermoplastic polyurethane, or from 30 to 35% by weight of at least one polyamide comprising amine chain ends, and from 65 to 70% by weight of at least one thermoplastic polyurethane, or from 35 to 40% by weight of at least one polyamide comprising amine chain ends, and from 60 to 65% by weight of at least one thermoplastic polyurethane, relative to the total weight of the polyamide comprising amine chain ends and the thermoplastic polyurethane.,

[0154] The foam according to the invention advantageously comprises from 1 to 40% by weight of at least one polyamide comprising amine chain ends and from 10 to 99% by weight of at least one thermoplastic polyurethane, preferably from 1 to 30% by weight of at least one polyamide comprising amine chain ends and from 15 to 89% by weight of at least one thermoplastic polyurethane, more preferably from 1 to 25% by weight of at least one polyamide comprising amine chain ends and from 15 to 89% by weight of at least one thermoplastic polyurethane. The foam may comprise from 1 to 5%, or from 5 to 10%, or from 10 to 15%, or from 15 to 20%, or from 20 to 25%, or from 25 to 30%, or from 30 to 35%, or from 35 to 40%, by weight, of at least one polyamide comprising amine chain ends, relative to the total weight of the foam.The foam may comprise from 10 to 20%, or from 20 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%, or from 90 to 99%, by weight, of at least one thermoplastic polyurethane, relative to the total weight of the foam.

[0155] The foam may further comprise at least one PEBA, advantageously in an amount, relative to the total weight of the foam, of 0 to 89% by weight, more preferably of 10 to 70% by weight. In particular, the foam may comprise from 0 to 10%, or from 10 to 20%, or from 20 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 89%, by weight, of PEBA, relative to the total weight of the foam. The foam may be free of copolymer containing polyamide blocks and polyether blocks. The above PEBA quantity ranges may each be combined with any of the polyamide quantity ranges including amine chain ends and / or any of the thermoplastic polyurethane quantity ranges mentioned above.

[0156] Preferably, the mass quantity of total soft blocks (i.e. soft blocks of thermoplastic polyurethane and PEBA when present) is 20 to 90%, more preferably 40 to 80%, even more preferably 50 to 75%, relative to the total weight of TPU and PEBA if present. The mass quantity of total soft blocks can be determined by nuclear magnetic resonance (NMR).

[0157] The molar ratio of the urethane functions to the NH2 amine functions of the assembly consisting of at least one polyamide comprising amine chain ends and at least one thermoplastic polyurethane, in the foam according to the invention, may be from 15 to 350, preferably from 25 to 250, even more preferably from 40 to 200. The concentrations of amine functions and urethane functions can be determined by 13C NMR in DMSO D6 as 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.

[0158] Preferably, the total amount of polyamide (of the PA with amine chain ends and of the optional PEBA) in the foam is at least 15% by weight, preferably at least 20% by weight, more preferably at least 25% by weight, more preferably at least 30% by weight, more preferably at least 35% by weight (relative to the total weight of the foam). The amount of polyamide in the foam can be determined by proton NMR in a TFA / CDCIs mixture (1 / 4 v / v), 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 (the assignment of the signals being carried out using figure 5 of said article).Advantageously, the TPU and PA foam according to the invention comprises at least a portion of the total polyamide covalently bonded to thermoplastic polyurethane by a urea function.

[0159] Preferably, the foam according to the invention has a urea function concentration of 0.001 meq / g to 0.1 meq / g, preferably 0.003 meq / g to 0.08 meq / g, more preferably 0.005 meq / g to 0.05 meq / g. The urea function concentration in the foam may be 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 0.08 meq / g, or 0.08 to 0.1 meq / g. The urea function concentration can be measured by 13C NMR in DMSO D6, as 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. The signals corresponding to the carbonyl groups of urethane and urea functions are integrated in order to determine a urea function rate, and the assignment of the signals is made using Figure 6 of said article.

[0160] Preferably, the portion of the polyamide covalently bonded to thermoplastic polyurethane by a urea function represents 10% or less by weight, more preferably 5% or less by weight, more preferably 3% or less by weight, more preferably 2% or less by weight, of the amount of polyamide.

[0161] The foam according to the invention may consist essentially of, or consist of, at least one polyamide with amine chain ends, at least one thermoplastic polyurethane, optionally at least one copolymer with polyamide blocks and polyether blocks, and optionally a blowing agent, in the matrix of the foam and / or in the pores of the foam, in particular if it is a closed-pore foam. The matrix of the foam may consist essentially of, or consist of, at least one TPU, at least one PA with amine chain ends and optionally at least one PEBA. The foam may also comprise degradation products of a blowing agent (in particular in its matrix), in particular when a chemical blowing agent has been used to form the foam.

[0162] Alternatively, the foam may include one or more additives, for example, ethylene vinyl acetate copolymers or EVA (for example, 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 be used to adjust the hardness of the foamed part, its appearance and its comfort.Other additives suitable 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 oxide), nucleating agents (particularly in pure or concentrated form, e.g., CaCOs, ZnO, SiO2, or combinations of two or more thereof), rubbers (to improve rubbery elasticity, such as natural rubber, SBR, polybutadiene and / or ethylene propylene terpolymers), stabilizers (e.g., antioxidants, UV absorbers and / or flame retardants), processing aids (e.g., stearic acid), antioxidants, including phenolic antioxidants such as IRGANOX from Ciba Geigy Inc.The additives may be present in a content of 0 to 30% by weight, preferably 0.1 to 20% by weight, more preferably 0.2% to 10% by weight, relative to the total weight of the foam.

[0163] According to one embodiment, the foam does not comprise crosslinkers. The foam is advantageously a non-crosslinked foam.

[0164] The foam according to the invention preferably has a density less than or equal to 800 kg / m 3 , preferably still less than or equal to 600 kg / m 3 , more preferably less than or equal to 400 kg / m 3 , even more preferably less than or equal to 300 kg / m 3 , and particularly preferably less than or equal to 230 kg / m 3 . For example, it can have a density of 25 to 600 kg / m 3 , and more particularly preferably from 50 to 300 kg / m 3 The density of the foam can range from 25 to 100 kg / m3 , or from 100 to 200 kg / m 3 , or 200 to 250 kg / m 3 , or 250 to 300 kg / m 3 , or 300 to 400 kg / m 3 , or 400 to 500 kg / m 3 , or 500 to 600 kg / m 3 , or 600 to 800 kg / m 3 Density control can be achieved by adapting the manufacturing process parameters. Density can be measured at 23°C according to ISO 1183-1.

[0165] Preferably, the foam according to the invention has an Asker C hardness of 20 to 90, preferably 25 to 70. In particular, the Asker C hardness of the foam may be 20 to 25, or 25 to 30, or 30 to 40, or 40 to 50, or 50 to 60, or 60 to 70, or 70 to 80, or 80 to 90. The Asker C hardness may be determined at 23°C, after 15 seconds, according to ISO 7619-1. 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.

[0166] Preferably, this foam has a compression set according to ISO 7214, 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 relaxation for 30 minutes.

[0167] Preferably, this foam also exhibits excellent fatigue resistance and damping properties.

[0168] Preferably, this foam also has good resistance to tearing and crack propagation.

[0169] The foam according to the invention can be used to manufacture sports equipment, such as soles of sports shoes, ski boots, midsoles, insoles, or even functional components of soles, in the form of inserts in different parts of the sole (heel or arch of the foot for example), or even components of the uppers of shoes in the form of reinforcements or inserts in the structure of the upper of the shoe, in the form of protections.

[0170] It can also be used to make balls, sports gloves (e.g. football gloves), golf ball components, rackets, protective elements (vests, interior elements of helmets, shells, etc.).

[0171] The foam according to the invention has interesting anti-shock, anti-vibration and anti-noise properties, combined with haptic properties suitable for capital goods. It can therefore also be used for the manufacture of railway rail bases, or various parts in the automotive industry, in transport, in electrical and electronic equipment, in construction or in the manufacturing industry.

[0172] 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 having cut them into pieces). Preparation of the foam

[0173] The foam according to the invention can be prepared by mixing a polymer composition comprising at least one TPU, at least one PA comprising amine chain ends and optionally at least one PEBA, with a blowing agent (and optionally with one or more additives), then carrying out a foaming step.

[0174] The blowing 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. Also preferably, it may also be a chemical agent, such as, for example, azodicarbonamide or mixtures based on citric acid and sodium hydrogen carbonate (NaHCOs) (such as the product from the Clariant Hydrocerol® range).

[0175] In embodiments, a physical blowing agent is used and is mixed with the polymer composition in the molten state. The physical blowing agent may be in liquid or supercritical form and is then converted to the gas phase during the foaming step. Foaming may be caused by a pressure drop, for example resulting from the exit of an extruder.

[0176] 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 caused by opening the mold, by under-dosing, by applying gas counter-pressure, by a breathable mold or by a mold equipped with a Variotherm® system. These techniques make it possible to directly produce three-dimensional foamed objects with complex geometries. They are also relatively simple techniques to implement, particularly compared to certain foamed particle fusion processes: in fact, filling the mold with foamed polymer granules and then melting the particles to ensure mechanical strength of the parts without destroying the structure of the foam are complex operations.

[0177] In alternative embodiments, the polymer composition is used to create a preform. This can be prepared by compression molding, extrusion, injection molding, lamination or 3D printing processes. Preferably, the preform is produced by extrusion or injection molding. This preform, in the solid state, is brought into contact with a physical expansion agent in gaseous or supercritical form. The physical expansion 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 within the autoclave is maintained between 0.20 and 50 MPa during the foaming. Advantageously, the foaming of the preform is contained in a mold.

[0178] Other foaming techniques that can be used include batch foaming, extrusion foaming, such as single-screw or twin-screw extrusion foaming, and microwave foaming.

[0179] Particularly preferably, the polymer composition comprising TPU, PA and optionally PEBA is prepared prior to its mixing with the blowing agent. Preferably, the polymer composition is an alloy of TPU, PA and optionally PEBA. By "alloy" is meant a homogeneous mixture (macroscopically, i.e. to the naked eye).

[0180] According to a first advantageous variant, the polymer composition can be prepared by a process comprising a step of mixing the polyamide comprising amine chain ends and thermoplastic polyurethane, and optionally the copolymer with polyamide blocks and polyether blocks, in the molten state. Such a preparation process allows, under certain temperature and mixing time conditions, for a reaction to take place between the amine functions of a portion of the polyamide and the urethane functions of the TPU, which improves the compatibility between the polyamide and the thermoplastic polyurethane.

[0181] The mixing of TPU, PA and optionally PEBA can take place in any device for mixing, kneading or extruding plastics in the molten state known to those skilled in the art, such as an internal mixer, a barrel mixer, an extruder, such as a single-screw extruder or a contra- or co-rotating twin-screw extruder, a co-kneader, such as a continuous co-kneader, or a stirred reactor. Preferably, the mixing takes place in an extruder or a co-kneader, more preferably in an extruder, even more preferably in a twin-screw extruder.

[0182] Preferably, the mixing is carried out at a temperature greater than or equal to 160°C, preferably from 160 to 300°C, more preferably from 180 to 260°C. These temperature ranges allow an optimal reaction between the polyamide comprising amine chain ends and the thermoplastic polyurethane, and therefore better compatibility of the two polymers.

[0183] Advantageously, the mixing is carried out for a period of 30 seconds to 15 minutes, preferably 40 seconds to 10 minutes. Preferably, the mixing is carried out with stirring. These mixing conditions allow an optimal reaction between the polyamide comprising amine chain ends and the thermoplastic polyurethane, and therefore better compatibility of the two polymers.

[0184] The step of mixing the TPU with the PA (and optionally the PEBA) may comprise mixing the polyamide comprising amine chain ends, thermoplastic polyurethane and optionally the polyamide block and polyether block copolymer, in the molten state, with additives.

[0185] According to another advantageous variant, the polymer composition can be prepared by introducing the polyamide comprising amine chain ends and optionally the polyamide block and polyether block copolymer during the synthesis of the thermoplastic polyurethane. In such a preparation method, the polyamide comprising amine chain ends, and optionally the polyamide block and polyether block copolymer, are used as isocyanate-reactive compounds (as described above in the section "Thermoplastic polyurethane (TPU)"), optionally in addition to another isocyanate-reactive compound, preferably a polyol as described above.

[0186] Thus, the preparation process may comprise the steps of:

[0187] - 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);

[0188] - introduction into the reactor of the polyamide comprising amine chain ends,

[0189] - optionally introduction into the reactor of the copolymer with polyamide blocks and polyether blocks;

[0190] - synthesis of thermoplastic polyurethane in the reactor in the presence of the polyamide comprising amine chain ends (and optionally the copolymer with polyamide blocks and polyether blocks), so as to obtain the polymer composition.

[0191] Such a preparation process allows the reaction of the NH2 amine functions of a part of the polyamide with the isocyanate functions of a part of the polyisocyanate during the synthesis of the thermoplastic polyurethane, leading to the formation of covalent bonds between the polyamide and the thermoplastic polyurethane, which improves the compatibility between the polyamide and the thermoplastic polyurethane.

[0192] The steps of introducing the precursors of the thermoplastic polyurethane, introducing the polyamide comprising amine chain ends and introducing the copolymer containing polyamide blocks and polyether blocks may be simultaneous or carried out in any order. A catalyst, in particular as described above, may also be introduced into the reactor.

[0193] The reactor may be a batch reactor, a stirred reactor, a static mixer, an internal mixer, a barrel mixer, an extruder, such as a single-screw extruder or a contra- or co-rotating twin-screw extruder, a continuous co-kneader, or a combination thereof. Preferably, the reactor is an extruder, more preferably a twin-screw extruder.

[0194] Preferably, the step of synthesizing the thermoplastic polyurethane (in the presence of the polyamide comprising amine chain ends and optionally the copolymer with polyamide blocks and polyether blocks) is carried out at a temperature greater than or equal to 160°C, preferably from 160 to 300°C, more preferably from 180 to 270°C. These temperature ranges allow an optimal reaction between the polyamide comprising amine chain ends and the thermoplastic polyurethane, and therefore better compatibility of the two polymers.

[0195] One or more additives may be introduced into the reactor (at any point in the process) and mixed with the thermoplastic polyurethane, the polyamide comprising amine chain ends, and optionally the polyamide block and polyether block copolymer, in the reactor.

[0196] Regardless of the variant used, the preparation process may include a step of shaping the mixture of TPU, PA and optionally PEBA into granules or powder. When the mixture is formed into powder, it is preferably first formed into granules and then the granules are ground into powder. Any type of mill may be used, such as a hammer mill, a pin mill, an attrition disc mill or an impact classifier mill.

[0197] In the processes for preparing the polymer composition described above, all the characteristics described above in relation to the polyamide, the thermoplastic polyurethane and the copolymer with polyamide blocks and polyether blocks (in particular their nature, their quantity, their concentration in OH, COOH and / or amine function, etc.) can be applied in a similar manner to the polyamide, the thermoplastic polyurethane and the copolymer with polyamide blocks and polyether blocks used in these processes.

[0198] The following examples illustrate the invention without limiting it.

[0199] The following polymers were used:

[0200] - PEBA: 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.

[0201] - PA n°1: polyamide 11 comprising on average one amine chain end per molecule, and having a concentration in NH2 function of 0.476 meq / g.

[0202] - PA n°2: polyamide 6 / 6.6 / 12 (40 / 25 / 35 by mass) comprising amine chain ends, and having a concentration in NH2 function of 0.305 meq / g.

[0203] - TPU: TPU with rigid blocks based on 4,4'-MDI and 1,4-BDO (1,4-butanediol) and with soft polyether blocks (PTMG), with a hardness of 85 Shore A.

[0204] A polymer composition 1 was prepared by mixing 5 wt% of PA No. 1 and 95 wt% 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 flow rate of 8 kg / h. The composition was then dried under reduced pressure at 80°C to achieve a moisture content below 0.04%.

[0205] A 2-polymer composition was prepared by mixing 50 wt% of PA No. 1 and 50 wt% 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 flow rate of 8 kg / h. The composition was then dried under reduced pressure at 80°C to achieve a moisture content below 0.04%. A 3-polymer composition was prepared by mixing 5 wt% of PA No. 2, 25 wt% of PEBA and 70 wt% 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 flow rate 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%.

[0206] Foam evaluation

[0207] Mousses were then prepared:

[0208] - Foam 1 (comparative): made from TPU alone;

[0209] - Foam 2 (according to the invention): made from polymer composition 1.

[0210] - Foam 3 (comparative) made from polymer composition 2

[0211] - Foam 4 (according to the invention): made from polymer composition 3.

[0212] The 15 mm thick foams were prepared using an Arburg Allrounder 520A 150T injection molding machine, with a Trexel series IL physical expansion agent injection system. This machine uses Mucell® technology with partial mold opening (core-back process). The operating parameters are as follows:

[0213] - Sheath temperature: 250°C

[0214] - Mold geometry (mm): 200 x 100 x 1.6 mm

[0215] - Injection speed: 120 cm 3 / s

[0216] - Holding time before opening the mold: 1 s

[0217] - Holding pressure: 25.0 MPa

[0218] - Cooling time: 240 s

[0219] - Mold temperature: 15°C

[0220] - Mold opening length: 15 mm

[0221] The blowing agent used is nitrogen (N2) introduced at a rate of 0.7% by weight.

[0222] The properties of the following foams were evaluated:

[0223] - Density: according to ISO 1183-1, at 23°C, using the vertical thrust method in water; 5 repetitions were carried out.

[0224] - 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 quantity, the more homogeneous the foam.

[0225] - Rebound resilience: according to ISO 8307 except that an 18.8 g 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 on rebound); 5 repetitions were carried out.

[0226] - Asker C hardness (15 s): according to ISO 7619-1, measured with a Hildebrand Asker C durometer.

[0227] The results are presented in the following table:

[0228] [Table 1]

[0229] ND = not determined

[0230] Composition 2 (comparative) did not produce homogeneous foams (foam 3). The parameters were therefore not measured. The polyamide content with amine chain ends in composition 2 is too high.

[0231] The foams according to the invention have a lower and more homogeneous density than the comparative foams prepared from TPU alone or from a composition having a polyamide content comprising too high amine chain ends. Foam 2 also has a lower density and a higher rebound resilience for an equivalent hardness. Foam 4 has a lower density and a lower hardness for an equivalent rebound resilience. In conclusion, the foams according to the invention make it possible to obtain a better compromise of properties.

Claims

Claims Polymer foam comprising, relative to the total weight of the foam: - from 10 to 99% by weight, preferably from 15 to 89% by weight, of at least one thermoplastic polyurethane, and - from 1 to 40% by weight, preferably from 1 to 30% by weight, of at least one polyamide comprising amine chain ends, as detected by potentiometric assay in metacresol using a 0.02N perchloric acid solution, in which the polyamide is the reaction product of one or more monomers chosen from amino acids or aminocarboxylic acids, lactams and monomers resulting from the reaction between an aliphatic diamine and a dicarboxylic acid. Foam according to claim 1, in which at least a portion of the total polyamide is covalently linked to a thermoplastic polyurethane molecule by a urea function. Foam according to claim 2, wherein the concentration of urea function, as measured by 13C NMR in DMSO D6, is from 0.001 meq / g to 0.1 meq / g, more preferably from 0.003 meq / g to 0.08 meq / g, more preferably from 0.005 meq / g to 0.05 meq / g.Foam according to one of claims 1 to 3, in which the polyamide has a concentration of NH2 amine function, as measured by potentiometric dosage in metacresol using a 0.02N perchloric acid solution, of 0.01 meq / g to 2.0 meq / g, preferably of 0.02 to 1.5 meq / g, more preferably of 0.02 to 1 meq / g, even more preferably of 0.02 meq / g to 0.4 meq / g.

5. Foam according to one of claims 1 to 4, in which the at least one thermoplastic polyurethane is a copolymer with rigid blocks and soft blocks, in which: - the flexible blocks are chosen from polyether blocks, polyester blocks, polycarbonate blocks and a combination thereof, preferably the flexible blocks are chosen 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 units derived from 4,4'-diphenylmethane diisocyanate and / or 1,6-hexamethylene diisocyanate and, preferably, units derived from at least one chain extender chosen from 1,3-propanediol, 1,4-butanediol and / or 1,6-hexanediol.

6. Foam according to one of claims 1 to 5, in which the polyamide comprising amine chain ends is chosen from the group consisting of polyamide 11, polyamide 12, polyamide 10, polyamide 6, polyamide 6.10, polyamide 6.6, polyamide 10.10, polyamide 10.12, polyamide 6.13, polyamide 10.9, polyamide 12.9 and combinations thereof.

7. Foam according to one of claims 1 to 6, further comprising at least one copolymer with polyamide blocks and polyether blocks.

8. Foam according to one of claims 1 to 7, comprising, relative to the total weight of the foam, from 0 to 89% by weight, preferably from 10 to 70% by weight, of at least one copolymer with polyamide blocks and polyether blocks.

9. Foam according to claim 7 or 8, in which the copolymer with polyamide blocks and polyether blocks 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 / CDCIs mixture (1 / 4 v / v).

10. Foam according to one of claims 7 to 9, in which the polyamide blocks of the copolymer with polyamide blocks and polyether blocks are chosen from blocks of polyamide 6, polyamide 6.10, polyamide 6.12, polyamide 11, polyamide 10, polyamide 12, polyamide 6.13, polyamide 10.9 and / or polyamide 12.9; and / or the polyether blocks of the copolymer with polyamide blocks and polyether blocks are blocks of polyethylene glycol and / or polypropylene glycol and / or polytetrahydrofuran.

11. Foam according to one of claims 1 to 10, in which the polyamide comprising amine chain ends has a number-average molar mass of 1000 to 60000 g / mol, preferably of 2000 to 40000 g / mol, even more preferably of 3000 to 20000 g / mol.

12. Foam according to one of claims 1 to 11, having a density, as measured at 23°C according to standard ISO 1183-1, less than or equal to 800 kg / m 3, preferably less than or equal to 400 kg / m 3 , more preferably less than or equal to 300 kg / m 3 , even more preferably less than or equal to 230 kg / m 3 .

13. Method for manufacturing a foam according to one of claims 1 to 12, comprising the following steps: - the provision of a polymer composition comprising at least one thermoplastic polyurethane and at least one polyamide comprising amine chain ends, and where appropriate at least one copolymer with polyamide blocks and polyether blocks; - mixing said polymer composition with a blowing agent; and - foaming of the mixture of polymer composition and blowing agent. Method according to claim 13, wherein the blowing agent is mixed with the polymer composition in the molten state, the foaming of the mixture preferably being carried out in a mold. Method according to claim 13 wherein the blowing agent is a physical blowing agent and is mixed with the polymer composition in the form of a solid preform, the foaming of the mixture preferably being carried out in an autoclave. Article made of a foam according to one of claims 1 to 12 or comprising at least one element made of a foam according to one of claims 1 to 12, preferably chosen from sports shoe soles, balls, gloves, personal protective equipment, rail soles, automobile parts, construction parts and electrical and electronic equipment parts.

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