Thermoplastic polymer usable for manufacturing foam

Abstract

The invention relates to a thermoplastic polymer, preferably a thermoplastic elastomer, for which the temperature Tx is greater than the temperature To; Tx and To being measured by determining the curves of the elastic modulus (G') and the loss modulus (G'') as a function of temperature during a plane-plane rheology measurement under cooling; Tx corresponding to the temperature at the intersection of the elastic modulus and loss modulus curves; To corresponding to the temperature at the intersection of the tangents to the high-temperature logarithm of the elastic modulus curve and an inflection point of said curve. The invention also relates to a foam of such a copolymer, a method for manufacturing such a foam, and articles manufactured from such a foam. Figure 2 is shown for the abstract.

Description

Title of the invention: Thermoplastic polymer usable for the manufacture of a foam. Field of the invention

[0001] The present invention relates to a thermoplastic polymer, in particular an elastomer, which can be used in particular for the manufacture of an article, especially a foamed article. The invention also relates to a foam formed from this thermoplastic polymer and to a method for preparing such a foam. Technical background

[0002] In many fields, such as the field of sports shoe soles, increasingly lower density foams are sought in order to minimize the mass of articles incorporating said foams, for example, sports shoes. Furthermore, a good cellular structure of these foams is desired in order to maintain good mechanical properties, such as good rebound, sufficient hardness, and good resistance to compression set.

[0003] However, achieving both low density and good cell structure in a single foam presents a challenge. It is known that the foaming of a polymer involves a cell growth phase and a crystallization phase that solidifies the cell structure. For a foam to have a low density, it must have the thinnest possible cell walls. However, when cell walls are thin, during the cell growth phase, they will be easily punctured or torn if the cell wall strength is insufficient, resulting in a higher proportion of open cells and, consequently, degraded mechanical properties. Furthermore, using a more resistant polymer carries the risk that this resistant polymer will inhibit cell growth.

[0004] There is therefore a real need to supply thermoplastic polymers that can be used for the formation of a foam and that, during the foaming process, can exhibit very good cell wall strength, without hindering cell growth. Summary of the invention

[0005] The invention relates firstly to a thermoplastic polymer, preferably a thermoplastic elastomer, for which the temperature Tx is greater than the temperature To,

[0006] Tx and To being measured by determining the curves of the elastic modulus (G') and the loss modulus (G”) as a function of temperature during a plane-plane rheology measurement in cooling at 1 Hz, preceded by a holding time of 2 minutes at a temperature, the cooling following a ramp of 10°C / min up to a temperature T2, then a ramp of -2°C / min,

[0007] Tx corresponding to the temperature at the intersection of the curves of the elastic modulus (G') and the loss modulus (G”),

[0008] To corresponding to the temperature at the intersection of the tangent to the curve of the logarithm of the elastic modulus (G') at point Pi and the tangent to the curve of the logarithm of the elastic modulus (G') at point P2,

[0009] Pi corresponding to the point, whose abscissa is less than a temperature T3, where the derivative of the function represented by the curve of log(G') is the highest,

[0010] P2 corresponding to: • at the inflection point of the curve of the logarithm of the elastic modulus (G') when this curve includes a single inflection point, or • at the inflection point of the curve of the logarithm of the elastic modulus (G') where the derivative of the function represented by the curve of log(G') is the smallest when this curve includes several inflection points,

[0011] the thermoplastic polymer having a crystallization temperature Tc, and • when Tc is less than or equal to 140°C, Ti is 220°C, T2 is 180°C and T3 is 175°C, and • when Tc is greater than 140°C, Ti is Tc+ 80°C, T2 is Tc+ 40°C and T3 is Tc+ 35°C.

[0012] In embodiments, the thermoplastic polymer is chosen from the group consisting of polyamide and polyether block copolymers, thermoplastic polyetheresters, thermoplastic polyurethanes, preferably aliphatic thermoplastic polyurethanes, and combinations thereof, more preferably from the group consisting of polyamide and polyether block copolymers, thermoplastic polyetheresters and combinations thereof.

[0013] In some embodiments, the thermoplastic polymer is a copolymer of polyamide and polyether blocks, in which, preferably: • the polyamide blocks are selected from the group consisting of PA 11, PA 12, PA 6, PA 6.10, PA 6.12, PA 6.13, PA 10.9, PA 10.14, PA 12.9 blocks and mixtures and copolymers thereof; and / or • Polyether blocks are chosen from the group consisting of polytetrahydrofuran blocks, polyethylene glycol blocks, and mixtures, or copolymers, of these.

[0014] In embodiments, the difference between Tx and To (Tx-To) is at least 1, preferably at least 2, more preferably at least 3, even more preferably at least 5, even more preferably at least 10, even more preferably at least 20.

[0015] In embodiments, the thermoplastic polymer is a rigid block and soft block copolymer, in which the soft blocks have a number average molar mass greater than or equal to 1000 g / mol, preferably greater than or equal to 1800 g / mol, preferably even greater than or equal to 2000 g / mol.

[0016] In embodiments, the thermoplastic polymer is a branched polymer preferably having a weight average molar mass of 80,000 to 260,000 g / mol, preferably of 100,000 to 240,000 g / mol, more preferably of 120,000 to 220,000 g / mol.

[0017] In some embodiments, the thermoplastic polymer is a branched polymer comprising branching points formed by a residue of at least one branching agent selected from: • polyols containing at least three hydroxyl groups; • epoxide compounds whose number-average functionality (Efn) is greater than 2, preferably greater than or equal to 3; and • combinations of these.

[0018] In embodiments, the thermoplastic polymer is obtained by a preparation process comprising at least one step of mixing a branching agent with precursors of a thermoplastic polymer or a step of mixing a branching agent with a thermoplastic polymer in the molten state,

[0019] in which the branching agent is mixed in an amount of 0.05 to 3% by mass, preferably 0.1 to 2.5% by mass, more preferably 0.2 to 2% by mass, relative to the total mass of the branching agent and the precursors of the thermoplastic polymer or of the thermoplastic polymer, and in which preferably the branching agent is selected from polyols having at least three hydroxyl groups, epoxide compounds having a number-average functionality (Efn) greater than 2, preferably greater than or equal to 3, and combinations thereof.

[0020] In embodiments, the thermoplastic polymer is obtained by a preparation process comprising at least one step of mixing a branching agent with precursors of a thermoplastic polymer, wherein the branching agent is a polyol having at least three hydroxyl groups, and wherein the branching agent is mixed in an amount of 0.05 to 1% by mass, preferably 0.1 to 0.6% by mass, more preferably 0.2 to 0.5% by mass, relative to the total mass of the branching agent and the precursors of the thermoplastic polymer.

[0021] In embodiments, the thermoplastic polymer is obtained by a preparation process comprising at least one step of mixing a branching agent with a thermoplastic polymer in the molten state, wherein the branching agent is an epoxy compound having a number-average functionality (Efn) greater than 2, preferably greater than or equal to 3, and wherein the branching agent is mixed in an amount of 0.1 to 3% by mass, preferably 0.2 to 2.5% by mass, more preferably 0.5 to 2% by mass, relative to the total mass of the branching agent and the thermoplastic polymer.

[0022] The invention also relates to a composition comprising at least one thermoplastic polymer as described above, and optionally one or more additives and / or one or more additional polymers.

[0023] The invention also relates to a foam of a thermoplastic polymer as described above or of a composition as described above.

[0024] In embodiments, the foam has a density less than or equal to 800 kg / m3, preferably less than or equal to 600 kg / m3, preferably even less than or equal to 400 kg / m3, more preferably less than or equal to 300 kg / m3, even more preferably less than or equal to 250 kg / m3, even more preferably less than or equal to 200 kg / m3.

[0025] In embodiments, the percentage of open cells is less than or equal to 50% by number, preferably less than or equal to 40% by number.

[0026] In embodiments, the foam cells present in the part of the foam extending from the surface of the foam and having a thickness equal to one-quarter of the total thickness of the foam, have an average number diameter less than or equal to 65 pm, preferably less than or equal to 55 pm.

[0027] In embodiments, the foam has a rebound resilience greater than or equal to 55%, preferably greater than or equal to 60%.

[0028] 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, automotive and railway parts, construction parts and electrical and electronic equipment parts.

[0029] The invention also relates to a method for manufacturing a foam as described above, comprising the following steps: • a mixture of a thermoplastic polymer as described above, or of a composition as described above, preferably in the molten state, optionally with one or more additives, and with a blowing agent; and • the foaming of this mixture.

[0030] In embodiments, the mixture which is foamed is in a molten state, the process preferably being an injection foaming or extrusion foaming process.

[0031] In some embodiments, the process is a foam injection process comprising: • the injection of the mixture of thermoplastic polymer, or composition, and expanding agent into a mold; and • the foaming of the mixture in the mold;

[0032] wherein the injection is carried out at a temperature within the range of (To + 30°C) to (To + 150°C).

[0033] The present invention addresses the need expressed above. More particularly, it provides a thermoplastic polymer for forming a polymer foam exhibiting both low density, a homogeneous cell structure, and good mechanical properties, such as good rebound and low compression set. The polymer according to the invention makes it possible, in particular, to obtain a foam which, for a given Asker C hardness, has a lower density than foams formed from polymers not according to the invention.

[0034] This is achieved by means of a specific thermoplastic polymer, exhibiting particular planar-planar rheological properties during cooling, more specifically characterized by a temperature Tx (temperature at which the curves of the elastic modulus G' and loss G") intersect, which is higher than the temperature To (temperature at which the high-temperature tangent and the tangent at the inflection point of the logarithmic elastic modulus G' curve intersect). It was surprisingly discovered that the polymer according to the invention, satisfying the relationship Tx-To > 0, exhibits better foaming ability and allows for good cell wall strength during foam formation, without hindering cell growth.Without being bound by any particular theory, the inventors believe that the temperature To corresponds to the temperature at which the polymer begins to crystallize and the cellular structure begins to solidify, and the temperature Tx corresponds to the temperature at which the polymer's deformation transitions from a predominantly viscous to a predominantly elastic deformation. Thus, by using a thermoplastic polymer for which Tx is greater than To, cell growth can be achieved during foam manufacturing through plastic deformation of the polymer. This allows the cell walls to be stretched without puncturing or tearing them, resulting in a good cellular structure in the foam. Conversely, if cell growth occurs... Due to plastic deformation of the polymer, the polymer will tend to flow, which may increase the appearance of holes in the cell walls, or even prevent the maintenance of the foam structure. Brief description of the figures

[0035] [Fig. 1] shows the curves of the elastic modulus G' (solid line) and the loss modulus G” (dashed line) obtained in plane-plane rheology during cooling for TPE No. 2 as described in the Examples below. The temperature (in °C) is shown on the x-axis and the modulus (G' and G”) in Pa is shown on the y-axis on a logarithmic scale. The temperatures TB T2 and T3 used for the rheology measurement are shown in this figure.

[0036] [Fig. 2] shows the curves of the elastic modulus G' (solid line) and the loss modulus G” (dashed line) obtained in plane-plane rheology during cooling for TPE No. 2 as described in the Examples below. The temperature (in °C) is shown on the x-axis and the modulus (G' and G”) in Pa is shown on the y-axis on a logarithmic scale. This figure shows the temperature Tx, as well as the points P1 and P2, and the tangents to the curve of the logarithm of the elastic modulus G' at these points, allowing the determination of the temperature T0.

[0037] [Fig.3] is a scan electron microscopy (SEM) image of the alveolar structure of comparative foam No. 4 as described in the Examples below.

[0038] [Fig.4] is a picture obtained by SEM of the alveolar structure of foam no. 6 according to the invention as described in the Examples below. Detailed description

[0039] The invention is now described in more detail and in a non-limiting manner in the following description.

[0040] Unless otherwise stated, all percentages are mass percentages.

[0041] 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.

[0042] A first object of the invention relates to a thermoplastic polymer. Preferably, the polymer is a thermoplastic elastomer (TPE). By "thermoplastic elastomer" is meant a block copolymer comprising, alternately, blocks or segments described as hard or rigid (with predominantly thermoplastic behavior) and blocks or segments described as soft or flexible (with predominantly elastomeric behavior). Generally, in this text, "rigid block" is understood to mean a block that has a melting point. 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 having 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.

[0043] The rigid blocks of the thermoplastic polymer according to the invention are advantageously chosen from the group consisting of polyamide blocks, polyurethane blocks, polyester blocks and copolymers and mixtures thereof.

[0044] The flexible blocks of the thermoplastic polymer are advantageously chosen from the group consisting of polyether blocks, polyester blocks, polycarbonate blocks, polysiloxane blocks such as polydimethylsiloxane (or PDMS) blocks, polyolefin blocks and copolymers and mixtures thereof.

[0045] The thermoplastic polymer according to the invention is preferably selected from polyamide-polyether block copolymers (PEBA), thermoplastic polyetheresters (TPEE or COPE), thermoplastic polyurethanes (TPU), and mixtures thereof. In advantageous embodiments, the thermoplastic polymer according to the invention is selected from PEBA, TPEE, and mixtures thereof.

[0046] Polyamide block copolymer and polyether block copolymer (PEBA)

[0047] 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:

[0048] 1) of polyamide blocks with diamine chain ends with polyoxyalkylene blocks with dicarboxylic chain ends;

[0049] 2) of polyamide blocks with dicarboxylic chain ends with blocks polyoxyalkylenes with diamine chain ends, obtained for example by cyanoethylation and hydrogenation of aliphatic α,co-dihydroxylated polyoxyalkylene blocks called polyetherdiols;

[0050] 3) of polyamide blocks with dicarboxylic chain ends containing polyetherdiols, the products obtained being, in this particular case, polyetheresteramides.

[0051] 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.

[0052] Three types of polyamide blocks can be advantageously used.

[0053] 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.

[0054] 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.

[0055] 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)-norbomane (BAMN) and piperazine (Pip).

[0056] 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 PA 10.18 are used. In the notation "PA XY," 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.

[0057] 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 caprolactam, oenantholactam, and lauryllactam. Examples of α,co-aminocarboxylic acids include aminocaproic, 7-aminoheptanoic, 10-aminodecanoic, 11-aminoundecanoic, and 12-aminododecanoic acids.

[0058] 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 notation "PA X", X represents the number of carbon atoms derived from amino acid residues or lactam residues.

[0059] 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.

[0060] 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 the α,co- acids 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.

[0061] 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).

[0062] 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. Examples of cycloaliphatic diacids include 1,4-cyclohexyldicarboxylic acid.Examples of aliphatic diacids include butanedioic, adipic, azelaic, suberic, sebacic, and dodecanedicarboxylic acids, as well as dimerized fatty acids. These dimerized fatty acids preferably have a dimer content of at least 98% and are preferably hydrogenated. Examples include products marketed under the brand name "PRIPOL" by CRODA, under the brand name EMPOL by BASF, and under the brand name Radiacid by OLEON, and α,β-co-polyoxyalkylenes. 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-cyclo-. Hexyl-methane (PACM). Other commonly used diamines may include isophoronediamine (IPDA), 2,6-bis-(aminomethyl)-norbomane (BAMN) and piperazine.

[0063] Examples of third-type polyamide blocks include PA 6.6 / 6 and PA 6.6 / 6.10 / 11 / 12.

[0064] 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. "Homopolyamide" in the context of the invention means the polymerization products of aminocarboxylic acid, lactam, or diacid monomers with diamines. "Copolyamide" in the context of the invention means a copolymer resulting from the polymerization of at least two different monomers, called "co-monomers," that is, at least one monomer and at least one comonomer (a monomer different from the first monomer), which are selected from aminocarboxylic acids, lactams, and diamine-diacid pairs.The copolyamide may comprise a major monomer, representing at least 80% by mass of the total mass of the monomer mixture, and at least one minor comonomer, representing a maximum of 20% by mass of the total mass of the monomer(s) and comonomer(s). The term "monomer" in this description should be understood as a "repeating unit." The case where a repeating unit consists of the association of a diacid with a diamine is a special one. The association of a diamine and a diacid, that is, the diamine-diacid pair (in equimolar quantities), is considered to constitute the monomer. This is because, individually, the diacid or the diamine is only a structural unit, which is insufficient on its own to form a polymer.

[0065] Advantageously, the polyamide blocks of the copolymer used in the invention comprise, or are selected from, 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 7.12, PA 7.13, PA 7.14, 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 blocks of polyamide PA 6, PA 10, PA 11, PA 12, PA 5.10, PA 5.12, PA 5.14, PA 5.16, PA 6.10, PA 6.12, PA 6.13, PA 6.14, PA 7.12, PA 7.13, PA 7.14, PA 10.9, PA 10.10, PA 10.12, PA 10.13, PA 10.14, PA 12.9 or mixtures or copolymers thereof, more preferably blocks of polyamide PA 6, PA 11, PA 12, PA 5.10, PA 5.12, PA 5.14, PA 5.16, PA 6.10, PA 6.12, PA 6.13, PA 6.14, PA 10.9, PA 10.10, PA 10.12, PA 10.13, PA 10.14, PA 12.9 or mixtures or copolymers thereof, even more. preferably blocks of polyamides PA 11, PA 12, PA 6, PA 6.10, PA 6.12, PA 6.13, PA 10.9, PA 10.14, PA 12.9 and mixtures, and copolymers, of these.

[0066] The polyether blocks are made up of alkylene oxide motifs.

[0067] Polyether blocks may in particular be PEG (polyethylene glycol) blocks That is to say, composed of ethylene oxide units, and / or PPG (propylene glycol) blocks, that is to say, composed of propylene oxide units, and / or PO3G (polytrimethylene glycol) blocks, that is to say, composed of polytrimethylene glycol ether units, and / or PTMG (polytetramethylene glycol, also called polytetrahydrofuran) blocks, that is to say, composed of tetramethylene glycol units. PEBA copolymers can include several types of polyethers in their chain; the copolyethers can be block or random.

[0068] Preferably, the polyether blocks of the PEBA are blocks of polyethylene glycol and / or polypropylene glycol and / or polytetrahydrofuran. Even more preferably, the polyether blocks of the PEBA are blocks of polyethylene glycol and / or polytetrahydrofuran.

[0069] Polyether blocks can also be made of ethoxylated primary amines. Examples of ethoxylated primary amines include products with the following formulas:

[0070] [Chem.l] H—(OCH2CH2X a — N—(CH2CH2O) r — H (CHA ch3

[0071] 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.

[0072] Preferably, for the preparation of PEBA, polyetherdiol blocks are copolycondensed with polyamide blocks with carboxylic ends.

[0073] 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,β-co-dihydroxylated polyoxyalkylene blocks (polyetherdiols).

[0074] PEBAs according to 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 selected from those described herein description, provided that these blocks include at least one polyamide block and one polyether block.

[0075] In addition, the PEBA according to 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.

[0076] For example, the copolymer according to the invention 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. This 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. The triblock is preferably a copolyetheresteramide.

[0077] Particularly preferred PEBA copolymers within the framework of the invention are copolymers comprising blocks of: PA 11 and PEG; PA 11 and PTMG; PA 12 and PEG; PA 12 and PTMG; PA 6 and PEG; PA 6 and PTMG; PA 6.12 and PEG; PA 6.12 and PTMG; PA 10.10 and PEG; PA 10.10 and PTMG; PA 10.12 and PEG; PA 10.12 and PTMG; PA 6.13 and PEG; or PA 6.13 and PTMG. Thermoplastic polyurethane (TPU)

[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, preferably 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-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), 1,4-bis(isocyanatomethyl)cyclohexane, 1,3-bis(isocyanatomethyl)cyclohexane, hyl)cyclohexane (HXDI), 2,4-paraphenylene diisocyanate (PPDI), 2,4-tetramethylene xylene diisocyanate (TMXDI), 4,4'-, 2,4'- and / or 2,2'-dicyclohexylmethane diisocyanate (H 12 MDI), 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'-dimethyl-diphenyl diisocyanate, 1,2-diphenylethane diisocyanate, phenylene diisocyanate, methylene bis (4-cyclohexylisocyanate) (HMDI) and mixtures thereof.

[0081] More particularly, the polyisocyanate can be chosen from the group consisting of tri-, tetra-, penta-, hexa-, hepta- and / or octamethylene diisocyanate and mixtures thereof.

[0082] Preferably, the polyisocyanate comprises between the terminal isocyanate functions a linear chain having from 5 to 10 carbon atoms, more preferably from 5 to 8 carbon atoms; for example a linear chain having 5, or 6, or 7, or 8, or 9, or 10 carbon atoms.

[0083] More preferably, the polyisocyanate is chosen from the group consisting of penta-, hexa-, hepta-, octa-, nona- and / or decamethylene diisocyanate and mixtures thereof.

[0084] Even more preferably, the polyisocyanate is 1,5-PDI (1,5-pentamethylene diisocyanate), 1,6-HDI (1,6-hexamethylene diisocyanate), nonamethylene diisocyanate, decamethylene diisocyanate, or a mixture thereof. Even more preferably, the polyisocyanate is selected from 1,5-pentamethylene diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, and mixtures thereof. Advantageously, the polyisocyanate is bio-based; bio-based polyisocyanates include, in particular, 1,5-pentamethylene diisocyanate, nonamethylene diisocyanate, and decamethylene diisocyanate. Generally, a "bio-based compound" is understood to mean a compound comprising 14C; preferably, the bio-based compounds according to the invention comprise at least 0.2x10 10% by mass of 14C relative to total carbon (corresponding to a biomass carbon content of at least approximately 20% by mass relative to the total carbon mass). The 14C content can be determined by mass spectrometry according to ASTM D6866-06.

[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, in a particularly advantageous way, the compound reactive 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, such 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 the thermoplastic polyurethane are polyether blocks and / or polyester blocks (the polyol being a polyether polyol and / or a polyester polyol). Even more preferably, the flexible blocks of the thermoplastic polyurethane are polyether blocks (the polyol being a polyether 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. The polyether polyol may in particular be a polyetherdiol based on ethylene oxide, propylene oxide, and / or butylene oxide, a block copolymer based on ethylene oxide and propylene oxide, polyethylene glycol (PEG), polypropylene glycol (PPG), polybutylene glycol, polytetrahydrofuran (PTMG), or a mixture thereof. More specifically, polyether polyol can be 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).

[0089] In embodiments, the polyether polyol comprises repeating motifs having at least 4 carbon atoms, for example repeating motifs having 4, or 5, or 6 carbon atoms.

[0090] Preferably, the polyether polyol is a polytetrahydrofuran. The polyether polyol may be a polyetherdiol, which is the reaction product of ethylene oxide and of 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.

[0091] The polysiloxane diols usable in the invention preferably have a number-average molar mass of 500 to 15,000 g / mol, preferably from 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):

[0092] [Chem.2] HO-[RO]nR-Si(R')2-[O-Si(R')2]mO-Si(R')2-R-[OR]p-OH (I)

[0093] wherein R is preferably a C2-C4 alkylene, R' is preferably a CrC4 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):

[0094] [Chem.3] (II)

[0095] in which Me is a methyl group,

[0096] or the following formula (III):

[0097] [Chem.4] (III)

[0098] The polyalkylene diols usable in the invention are preferably butadiene-based.

[0099] 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. Specifically, 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.

[0100] Advantageously, the compound reactive with the isocyanate, preferably the polyol, is bio-based.

[0101] One or more polyols may be used as a reactive compound with the isocyanate.

[0102] In a particularly preferred manner, the flexible blocks of the TPU are blocks of polytetrahydrofuran, polypropylene glycol and / or polyethylene glycol.

[0103] A chain extender is used for the preparation of thermoplastic polyurethane, in addition to isocyanate and the compound reactive with isocyanate.

[0104] The chain extender may be aliphatic, araliphatic, aromatic, and / or cycloaliphatic. Preferably, the chain extender is linear (aliphaitic). It advantageously has a number-average molar mass of 50 to 499 g / mol. The number-average molar mass can 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.

[0105] The chain extender is preferably bifunctional. Examples of chain extenders are diamines and diols, and more particularly 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 (or propylene glycol), 1,3-propanediol (or trimethylene glycol), 1,4-butanediol (or tetramethylene glycol), 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.Preferably, the chain extender according to the invention is a diol chain extender comprising at most 8 carbon atoms, more preferably at most 6 carbon atoms; for example, a diol chain extender comprising 2, or 3, or 4, or 5, or 6, or 7, or 8 carbon atoms. 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 even more preferably it is selected from 1,3-propanediol, 1,4-butanediol and / or . 1,6-Hexanediol. Even more preferably, the chain extender is 1,4-Butanediol. The chain extender can also be a mixture of 1,4-Butanediol and 1,6-Hexanediol, particularly in a molar ratio of 6:1 to 10:1. Preferably, the chain extender is bio-based; examples of bio-based chain extenders include 1,4-Butanediol, 1,3-Propanediol, and 1,6-Hexanediol.

[0106] Preferably, the TPU according to the invention is an aliphatic or essentially aliphatic TPU (i.e., a TPU comprising at least 90% by mass, preferably at least 95% by mass, more preferably at least 97% by mass, and more preferably at least 99% by mass, of aliphatic units, relative to the total mass of the TPU). Thus, preferably, the TPU is prepared from one or more aliphatic polyisocyanates, one or more compounds reactive with the isocyanate, preferably aliphatic polyols, and one or more chain extenders, preferably aliphatic diols. In these embodiments, the polyisocyanates, the isocyanate-reactive compounds and the chain extenders can respectively be chosen from the aliphatic polyisocyanates mentioned above, the aliphatic isocyanate-reactive compounds mentioned above and the aliphatic chain extenders mentioned above.

[0107] 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.

[0108] 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 a titanium acid ester, an iron compound, preferably ferric acetylacetonate, a tin compound, preferably a carboxylic acid compound, 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. Most preferably, the catalyst is selected from the group consisting of tin dioctoate, bismuth decanoate, titanium acid esters, and mixtures thereof.Preferably, the catalyst is tin dioctoate.

[0109] Advantageously, the TPU may be recycled TPU and / or partially or completely bio-based TPU. Most advantageously, the TPU is not cross-linked. Thermoplastic polyetherester (TPEE)

[0110] The TPEEs comprise flexible polyether blocks derived from polyetherdiols and rigid polyester blocks resulting from the reaction of at least one dicarboxylic acid with at least one diol chain extender, preferably a short diol chain extender. The polyester blocks and the polyether blocks are linked by ester bonds resulting from the reaction of the acidic functions of the dicarboxylic acid with the OH functions of the polyetherdiol.

[0111] The diol chain extender can be chosen from the group consisting of neopentyl glycol, cyclohexanedimethanol and aliphatic glycols of formula H0(CH2)n0H in which n is an integer from 2 to 10. The glycols may be chosen from those mentioned above in the description of thermoplastic polyurethanes, and may in particular be ethylene glycol, trimethylene glycol, propylene glycol, tetramethylene glycol or a combination thereof.

[0112] Advantageously, the diacids are aromatic dicarboxylic acids having from 8 to 14 carbon atoms. Up to 50 mole percent of the aromatic dicarboxylic acid can be replaced by at least one other aromatic dicarboxylic acid having from 8 to 14 carbon atoms, and / or up to 20 mole percent can be replaced by an aliphatic dicarboxylic acid having from 2 to 14 carbon atoms.

[0113] Examples of dicarboxylic aromatic acids include terephthalic, isophthalic, bibenzoic, naphthalene dicarboxylic acid, 4,4'-diphenylenedicarboxylic acid, bis(p-carboxyphenyl)methane, ethylene bis p-benzoic acid, 1,4-tetramethylene bis(p-oxybenzoic acid), ethylene bis (p-oxybenzoic acid), 1,3-trimethylene bis (p-oxybenzoic acid) and furan dicarboxylic acid.

[0114] The polyether blocks can be as described above in the description of the PEBA. Thermoplastic polymer

[0115] Unless otherwise specified, the description of the thermoplastic polymer given in this section applies to all thermoplastic polymers according to the invention, regardless of their class, and in particular to PEBA, TPU, and TPEE described above. Furthermore, in the context of the invention, the term "thermoplastic polymer" may refer to a single thermoplastic polymer but also to mixtures of thermoplastic polymers, unless otherwise specified.

[0116] The polymer according to the invention has a crystallization temperature Tc. This crystallization temperature is measured by differential scanning calorimetry (DSC) according to ISO 11357-3:2013 using a heating rate of 20°C / min. When the thermoplastic polymer is a blend of thermoplastic polymers, the crystallization temperature Tc considered corresponds to the temperature Tc measured at the peak exhibiting the highest enthalpy.

[0117] The thermoplastic polymer according to the invention is such that its temperature Tx (crossover temperature) is greater than its temperature To (onset temperature) (in other words, the difference between Tx and To (Tx-To) is greater than 0).

[0118] The temperatures Tx and To associated with a thermoplastic polymer are determined by a plane-plane rheology measurement under 1 Hz cooling, by plotting the elastic modulus (G') and the loss modulus (G”) curves as a function of temperature. More specifically, to perform this rheological measurement, the polymer is first melted and then held at a temperature Ti for 2 minutes, followed by cooling at a rate of -10°C / min to a temperature T2, and then at a rate of -2°C / min. The term "logarithm of the elastic modulus G'" refers to the decimal logarithm or "log".

[0119] The temperature Tx corresponds to the temperature at which the curve of the elastic modulus G' and the curve of the loss modulus G” intersect.

[0120] The temperature To corresponds to the abscissa of the intersection between the tangent to the curve of the logarithm of the elastic modulus G' at the point Pi and the tangent to this same curve of the logarithm of the elastic modulus G' at the point P2. The points Pi and P2 of the curve of the logarithm of the elastic modulus G' are defined as follows.

[0121] The point Pi is the point on the curve, whose abscissa is less than a temperature T3, where the derivative of the function of the curve of the logarithm of G' is the highest (or the lowest in absolute value).

[0122] Point P2 is, when the curve of the logarithm of the elastic modulus (G') has a single inflection point, said inflection point, and, when the curve of the logarithm of the elastic modulus (G') has several (i.e., two or more) inflection points, the inflection point where the derivative of the function represented by the curve of the logarithm of G' is the lowest (or the highest in absolute value). The curve of the logarithm of the elastic modulus (G') may have several inflection points, for example, when the thermoplastic polymer is a mixture of different thermoplastic polymers.

[0123] The temperature Ti is 220°C when the temperature Te of the thermoplastic polymer is less than or equal to 140°C, and is Tc+ 80°C when the temperature Te of the thermoplastic polymer is greater than 140°C.

[0124] The temperature T2 is 180°C when the temperature Te of the thermoplastic polymer is less than or equal to 140°C, and is Tc+ 40°C when the temperature Te of the thermoplastic polymer is greater than 140°C.

[0125] Temperature T3 is 175°C when the temperature Te of the thermoplastic polymer is less than or equal to 140°C, and is Tc + 35°C when the temperature Te of the thermoplastic polymer is greater than 140°C. This 5°C difference between T2 and T3 prevents interference from disturbances related to the change in the cooling ramp at T2.

[0126] The rheology measurement is performed using a stress-imposed rheometer, with the following operating parameters: axial force set to 0 N, maximum moment value fixed at 0.01 Nm, measurement performed under imposed strain, said imposed strain being progressively decreased as follows: application of a 2% strain until the moment reaches 0.01 Nm, then a 1% strain until the moment again reaches 0.01 Nm, and so on, the imposed strain being halved each time the moment reaches 0.01 Nm.

[0127] Cooling is typically continued up to the limits of the measuring device, namely to the point where the device can no longer apply the imposed deformation.

[0128] Rheology measurement can be performed using the HR20 device from TA Instruments.

[0129] By "tangent to a curve at a given point", we mean the line whose slope is equal to the value of the derivative of the function represented by the curve at that given point, and which shares that point with the curve.

[0130] According to another aspect of the invention, the thermoplastic polymer is such that its temperature Tx is greater than its temperature To, Tx and To being measured by determining the curves of the elastic modulus (G') and the loss modulus (G”) as a function of temperature during a plane-plane rheology measurement in cooling at 1 Hz, preceded by a holding time of 2 minutes at 220°C, the cooling following a ramp of -10°C / min up to the temperature of 180°C then a ramp of at least -2°C / min until reaching an inflection point of the curve of G', Tx being as defined above and To corresponding to the temperature at the intersection of the tangent to the curve of the logarithm of the elastic modulus (G') at point Pi and the tangent to the curve of the logarithm of the elastic modulus (G') at point P2, Pi corresponding to the point whose abscissa is less than 175°C, where the derivative of the function represented by the curve of the logarithm of G' is the highest and P2 being as defined above.

[0131] Preferably, the difference between Tx and To (Tx-To) is greater than or equal to 1, preferably greater than or equal to 2, preferably greater than or equal to 3, preferably greater than or equal to 4, preferably greater than or equal to 5, more preferably greater than or equal to 8, more preferably greater than or equal to 10, more preferably greater than or equal to 20. The difference Tx-To may be at least 15, or at least 25, or at least 30.

[0132] In advantageous embodiments, the temperature To of the thermoplastic polymer according to the invention is from 90 to 160°C, for example from 90 to 120°C, or from 120 to 130°C, or from 130 to 140°C, or from 140 to 160°C.

[0133] Preferably, the flexible blocks of the thermoplastic polymer have a number-average molar mass (Mn) greater than or equal to 100 g / mol, preferably greater than or equal to 200 g / mol, more preferably greater than or equal to 650 g / mol; for example, an Mn of 100 to 6,000 g / mol, preferably 200 to 4,000 g / mol, more preferably 650 to 3,000 g / mol. In some embodiments, the flexible blocks may have a number-average molar mass greater than or equal to 800 g / mol, preferably greater than or equal to 1,000 g / mol, preferably greater than or equal to 1,800 g / mol, more preferably greater than or equal to 2,000 g / mol.

[0134] The rigid blocks of the thermoplastic polymer can have an average number molar mass Mn of 400 to 20000 g / mol, more preferably of 500 to 10000 g / mol, even more preferably of 600 to 6000 g / mol.

[0135] The number-average molar masses of the flexible and rigid blocks of the thermoplastic polymer can be measured, after copolymerization, by proton NMR. A person skilled in the art is able to determine the conditions (solvent, temperature) for solubilizing the thermoplastic polymer to perform the NMR measurement. For example, the Mn of the PEBA blocks 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 being carried out using Figure 5 of said article); the Mn of the TPU blocks can be determined 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; and the Mn of the blocks of the . TPEE can be determined by proton NMR in an HFIP / CD2C12 mixture at 23°C, or in C2D2C14 at 100°C.

[0136] The rigid block content in the thermoplastic polymer is preferably less than or equal to 90% by mass and even more preferably less than or equal to 80% by mass (relative to the total mass of the polymer). More advantageously, the rigid block content in the thermoplastic polymer is from 30 to 60% by mass (the flexible block content being from 40 to 70% by mass). The rigid block content can be measured by proton NMR as described above. These quantities allow for a foam with lower density, greater flexibility, and improved rebound resilience.

[0137] Advantageously, the thermoplastic polymer has a Shore D hardness greater than or equal to 30. Preferably, the thermoplastic polymer has an instantaneous hardness of 65 Shore A to 80 Shore D, more preferably of 75 Shore A to 65 Shore D, and more preferably of 80 Shore A to 55 Shore D. Hardness measurements can be carried out according to ISO 7619-1.

[0138] The thermoplastic polymer according to the invention preferably has a weight-average molar mass (Mw) of 40,000 to 260,000 g / mol, preferably of 80,000 to 240,000 g / mol. The weight-average molar mass Mw can be determined by gel permeation chromatography (GPC or size-exclusion chromatography), in particular according to ISO 16014-1:2012. More particularly, the weight-average molar mass is expressed in PMMA equivalents (used as a calibration standard), and the copolymer is solubilized in hexafluoroisoproponol stabilized with 0.05 M potassium trifluoroacetate for 24 h at room temperature at a concentration of 1 g / L before being passed through the columns, for example at a flow rate of 1 mL / min, the molar mass being measured by the refractive index.Size exclusion chromatography can be carried out using modified silica columns, for example on a set of two columns and a modified silica pre-column (such as the PGF columns and pre-columns from Polymer Standards Service) comprising a 1000 Å column, dimensions 300 x 8 mm and particle size 7 pm, a 100 Å column, dimensions 300 x 8 mm and particle size 7 pm and a pre-column dimensions 50 x 8 mm, for example at a temperature of 40°C.

[0139] The thermoplastic polymer according to the invention can be branched (or ramified) or linear.

[0140] When the thermoplastic polymer according to the invention is linear, it preferably has flexible blocks having a number-average molar mass Mn greater than or equal to 650 g / mol. More advantageously, the flexible blocks of the linear thermoplastic polymer have a number-average molar mass greater than or equal to 800 g / mol, preferably greater than or equal to 1000 g / mol. In modes In production, the flexible blocks have a number-average molar mass greater than or equal to 1500 g / mol, more preferably greater than or equal to 1800 g / mol, and even more preferably greater than or equal to 2000 g / mol. In particular, the flexible blocks of the linear thermoplastic polymer can have a number-average molar mass of 800 to 6000 g / mol, preferably 1000 to 4000 g / mol, for example 2000 to 3000 g / mol.

[0141] When the thermoplastic polymer according to the invention is branched, it preferably has a weight average molar mass (Mw) of 80,000 to 260,000 g / mol, preferably of 100,000 to 260,000 g / mol, more preferably of 100,000 to 240,000 g / mol, more preferably of 120,000 to 220,000 g / mol, for example of 120,000 to 160,000 g / mol, or of 160,000 to 220,000 g / mol. In other embodiments, the Mw of the thermoplastic polymer is greater than or equal to 125,000 g / mol, preferably greater than or equal to 130,000 g / mol, more preferably greater than or equal to 140,000 g / mol, even more preferably greater than or equal to 150,000 g / mol, such as greater than or equal to 160,000 g / mol, or greater than or equal to 170,000 g / mol, or greater than or equal to 180,000 g / mol, or greater than or equal to 200,000 g / mol.

[0142] When the thermoplastic polymer according to the invention is branched, it preferably has flexible blocks having a number average molar mass Mn greater than or equal to 100 g / mol, preferably greater than or equal to 200 g / mol, more preferably greater than or equal to 500 g / mol, more preferably greater than or equal to 650 g / mol; in particular the Mn of the flexible blocks can be from 100 to 3,000 g / mol, preferably from 200 to 3,000 g / mol, more preferably from 500 to 2,000 g / mol, more preferably from 650 to 2,000 g / mol.

[0143] The thermoplastic polymer may be a branched polymer comprising branching points (or branching points) made by the residue of at least one branching agent (or branching agent).

[0144] The branching agent can be any suitable branching agent having a functionality greater than 2, preferably greater than or equal to 3.

[0145] In particular, the branching agent may be chosen from the group consisting of polyols comprising at least three hydroxyl groups, epoxide compounds whose number-average functionality (Efn) is greater than 2, preferably greater than or equal to 3, and combinations thereof.

[0146] The addition of a branching agent with a functionality greater than two causes bridging bonds linking together blocks of the thermoplastic polymer, for example rigid blocks, in particular by ester bonds.

[0147] Thus, the branching agent can be a polyol comprising at least three hydroxyl groups. This polyol can notably be chosen from: • monomeric polyols, in particular monomeric aliphatic triols such as glycerol, trimethylolpropane, pentaerythritol, and / or • polymeric polyols, including polyether chain triols, polycaprolactone triols, mixed polyether-polyester polyols comprising at least three hydroxyl groups.

[0148] Advantageously, the polyol is selected from: pentaerythritol, trimethylolpropane, trimethylolethane, hexanetriol, diglycerol, methylglucoside, tetraethanol, sorbitol, dipentaerythritol, cyclodextrin, polyetherpolyols comprising at least three hydroxyl groups, and mixtures thereof.

[0149] The average molar mass by weight of the polyol is preferably at most 3000 g / mol, more preferably at most 2000 g / mol; and is generally in the range of 50 to 1000 g / mol, preferably 50 to 500 g / mol, preferably 50 to 200 g / mol.

[0150] The branching agent may be an epoxy compound having an average number epoxy functionality (Efn) greater than 2, preferably greater than or equal to 3.

[0151] The epoxy equivalent weight (EEW) of the epoxy compound is generally from 80 to 2800 g / mol, preferably from 80 to 700 g / mol.

[0152] The epoxy compound may be selected from triglycidyl isocyanurate, trimethylolpropane triglycidyl ether, epoxy-novolac resins and epoxy oils.

[0153] Alternatively or additionally, the epoxide compound of the present invention may be selected from statistical copolymers of (meth)acrylates with epoxide functions obtained by copolymerization of at least one (meth)acrylic monomer with epoxide function with at least one monomer selected from alkene monomers, vinyl acetate monomers, non-functional (meth)acrylic monomers, styrenic monomers and mixtures thereof.

[0154] Examples of these (meth)acrylic monomers with an epoxide function include monomers containing 1,2-epoxide groups such as glycidyl acrylate and glycidyl methacrylate. Other suitable monomers may be allyl glycidyl ether, glycidyl ethacrylate, and glycidyl itoconate.

[0155] Suitable alkene monomers are ethylene, propylene, butylene and mixtures thereof.

[0156] Suitable non-functional acrylate and methacrylate monomers may be methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, s-butyl acrylate, i-butyl acrylate, t-butyl acrylate, n-amyl acrylate, i-amyl acrylate, isobomyl acrylate, n-hexyl acrylate, 2-ethylbutyl acrylate, 2-ethylhexyl acrylate, acrylate n-octyl, n-decyl acrylate, methylcyclohexyl acrylate, cyclopentyl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, i-propyl methacrylate, i-butyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, i-amyl methacrylate, s-butyl methacrylate, i-amyl-butyl methacrylate, 2-ethylbutyl methacrylate, methylcyclohexyl methacrylate, cinnamyl methacrylate, crotyl methacrylate, cyclohexyl methacrylate, cyclopentyl methacrylate, 2-ethoxyethyl methacrylate, and methacrylate of isobornyl.

[0157] The styrenic monomers usable in the invention include, but are not limited to, styrene, alpha-methylstyrene, vinyltoluene, p-methylstyrene, t-butylstyrene, o-chlorostyrene, vinylpyridine, and mixtures thereof. In some embodiments, the styrenic monomers used in the invention are styrene and / or alpha-methylstyrene.

[0158] Preferably, the epoxide compound is chosen from among the statistical copolymers with epoxide functions obtained by copolymerization of at least one (meth)acrylic monomer with epoxide function and at least one styrenic and / or (meth)acrylic non-functional monomer.

[0159] Advantageously, the epoxide compound is a statistical copolymer of styrene and glycidyl methacrylate. Polymer synthesis

[0160] Generally and as is known, rigid block and flexible block polymers can be prepared by a two-step preparation process (comprising a first step of synthesis of rigid blocks and then a second step of condensation of rigid and flexible blocks or, alternatively, a first step of synthesis of flexible blocks and then a second step of condensation of rigid and flexible blocks) or by a one-step preparation process (flexible blocks are mixed with rigid block precursors or, alternatively, rigid blocks are mixed with flexible block precursors).

[0161] When the thermoplastic polymer according to the invention is branched, it can be prepared by adding one or more branching agents during the synthesis of the block copolymer from its precursors ("synthesis route") or by mixing one or more branching agents with the previously synthesized block copolymer in the molten state ("compounding route").

[0162] Thus, according to a first embodiment, the branching agent is mixed with precursors of a thermoplastic polymer. Preferably, the branching agent is mixed in an amount of 0.05 to 3% by mass, preferably 0.1 to 2% by mass, more preferably 0.2 to 2% by mass, relative to the total mass of the agent branching and precursors of the thermoplastic polymer. In particular, the branching agent may be mixed with the precursors of a thermoplastic polymer in an amount of 0.05 to 0.1% by mass, or 0.1 to 0.2% by mass, or 0.2 to 0.3% by mass, or 0.3 to 0.4% by mass, or 0.4 to 0.5% by mass, or 0.5 to 0.6% by mass, or 0.6 to 0.7% by mass, or 0.7 to 0.8% by mass, or 0.8 to 0.9% by mass, or 0.9 to 1% by mass, or 1 to 1.2% by mass, or 1.2 to 1.5% by mass, or 1.5 to 1.8% by mass, or 1.8 to 2% by mass, or 2 to 2.2% by mass, or 2.2 to 2.5% by mass, or 2.5 to 3% by mass, relative to the total mass of the branching agent and the precursors of the thermoplastic polymer.

[0163] More preferably, the branching agent is mixed with the precursors of a thermoplastic polymer in an amount of 0.05 to 1% by mass, preferably 0.1 to 0.6% by mass, more preferably 0.2 to 0.5% by mass, relative to the total mass of the branching agent and the precursors of the thermoplastic polymer.

[0164] More specifically, according to this first variant, the branched thermoplastic polymer is prepared according to a process comprising the following steps: • the supply of precursors for rigid blocks; • the synthesis of rigid blocks; • the addition of flexible blocks; and • the condensation of rigid blocks and flexible blocks;

[0165] the process further comprising a step of adding the branching agent, said branching agent being added before the synthesis of rigid blocks (in particular with the precursors of rigid blocks) and / or after the synthesis of rigid blocks (in particular with the soft blocks).

[0166] Alternatively, the branched thermoplastic polymer can be prepared by a process comprising the supply of soft block precursors, the synthesis of the soft blocks, the supply of the rigid blocks, and the condensation of the soft blocks and the rigid blocks, the process further comprising the addition of the branching agent, before the synthesis of the soft blocks (in particular with the soft block precursors) and / or after the synthesis of the soft blocks (in particular with the rigid blocks).

[0167] Preferably, in this first variant, the branching agent is a polyol comprising at least three hydroxyl groups.

[0168] According to a second embodiment, the branching agent is mixed with a thermoplastic polymer in the molten state.

[0169] Preferably, the branching agent is mixed in an amount of 0.05 to 3% by mass, preferably 0.1 to 2.5% by mass, more preferably 0.2 to 2% by mass, relative to the total mass of the branching agent and the thermoplastic polymer. In particular, the branching agent may be mixed with the thermoplastic polymer in the molten state in an amount of 0.05 to 0.1% by mass, or 0.1 to 0.2% by mass, or 0.2 to 0.3% by mass, or 0.3 to 0.4% by mass, or 0.4 to 0.5% by mass, or 0.5 to 0.6% by mass, or 0.6 to 0.7% by mass, or 0.7 to 0.8% by mass, or 0.8 to 0.9% by mass, or 0.9 to 1% by mass, or 1 to 1.2% by mass, or 1.2 to 1.5% by mass, or 1.5 to 1.8% by mass, or 1.8 to 2% by mass, or 2 to 2.2% by mass, or 2.2 to 2.5% by mass, or 2.5 to 3% by mass, relative to the total mass of the branching agent and the thermoplastic polymer.

[0170] More preferably, the branching agent is mixed with the thermoplastic polymer in the molten state in an amount of 0.1 to 3% by mass, preferably 0.2 to 2.5% by mass, more preferably 0.5 to 2% by mass, relative to the total mass of the branching agent and the thermoplastic polymer.

[0171] As a device for carrying out the mixing step, any device for mixing, kneading, or extruding molten plastics known to those skilled in the art may be used. Examples include internal mixers, roller mixers, single-screw, twin-screw, counter-rotating, or co-rotating extruders, continuous co-mixers, or stirred reactors. The kneading device may be one of the devices mentioned above or a combination thereof, such as a co-mixer combined with a single-screw re-extruder.

[0172] Preferably, the mixing step is a reactive extrusion step, typically carried out in an extruder.

[0173] Preferably, in this second variant, the branching agent is an epoxide compound whose number-average functionality (Efn) is greater than 2, preferably greater than or equal to 3.

[0174] In general, the Tx-To difference of the thermoplastic polymer can be increased, in particular: • by forming branches in the thermoplastic polymer and increasing the branching rate in this polymer; • by increasing the number-average molar mass of the flexible blocks of the thermoplastic polymer; and • by increasing the average molar mass by weight of the thermoplastic polymer.

[0175] Thus, by adjusting the various parameters above in combination, a person skilled in the art will be able to produce thermoplastic polymers for which the temperature Tx is greater than the temperature To and to increase the difference Tx-To. Thermoplastic polymer composition

[0176] The invention also relates to a composition comprising at least one thermoplastic polymer, preferably a thermoplastic elastomer, as defined above.

[0177] The composition may comprise a mixture of several polymers. In these embodiments, at least one of the polymers is a thermoplastic polymer as defined above (i.e., for which its temperature Tx is greater than its temperature To).

[0178] The composition may comprise a mixture of several thermoplastic polymers, preferably thermoplastic elastomers, as described above (i.e. it may comprise at least two thermoplastic polymers as described above, for example at least three, or at least four thermoplastic polymers as described above).

[0179] The composition according to the invention may include one or more additional polymers (i.e. other than the thermoplastic polymers described in the preceding section), for example, selected from the group consisting of polyamides, functional polyolefins, ethylene and vinyl acetate copolymers (for example, the products marketed under the Evatane brand by SK functional polymer), ethylene and acrylate copolymers, or ethylene and alkyl(meth)acrylate copolymers (for example, the products marketed under the Lottyl brand by SK functional polymer), rubbers (in particular, to improve rubbery elasticity, such as natural rubber, SBR, polybutadiene and / or ethylene propylene terpolymers), TPEs for which Tx is less than or equal to To and mixtures thereof.

[0180] These additional polymers can be used to adjust the hardness of the polymer composition. They can be present in an amount of 0 to 30% by mass, preferably 5 to 30% by mass, relative to the total mass of thermoplastic polymer according to the invention present in the composition.

[0181] The composition according to the invention may also include one or more additives, such as pigments (TiO2 and other compatible color pigments), adhesion promoters (to improve the adhesion of the foam to other materials), nucleating agents (in pure or concentrated form), for example, ZnO, plasticizers, stabilizers, for example, antioxidants, UV absorbers and / or flame retardants, additives to improve processability (“processing aids”), for example, stearic acid, and fillers, for example, calcium carbonate, barium sulfate and / or silicon dioxide. Typically, the composition may comprise from 0.5 to 40% by mass of additives relative to the total mass of the composition.In particular, the composition may include 5 to 30% by mass of fillers relative to the total mass of the composition and / or 0.5 to 10% by mass of additives selected from pigments, adhesion promoters, nucleating agents, plasticizers, stabilizers and additives to improve processability.

[0182] Advantageously, the composition comprises at least 60% by mass of thermoplastic polymer according to the invention relative to the total mass of the composition. Preferably, the composition comprises at least 80% by mass, more preferably at least 90% by mass, and more preferably at least 95% by mass, for example at least 99% by mass, of thermoplastic polymer according to the invention relative to the total mass of the composition. Polymer foam

[0183] The thermoplastic polymer (or the composition comprising it) can be used to form a foam, preferably non-crosslinked.

[0184] The foam according to the invention may have a composition such as described above in the preceding section concerning the thermoplastic polymer composition. In particular, the foam may comprise the components mentioned in that section, in the quantities indicated therein.

[0185] The foam matrix may consist essentially of, or consist of, at least one thermoplastic polymer according to the invention or the thermoplastic polymer composition according to the invention. 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.

[0186] 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, more preferably less than or equal to 300 kg / m3, more preferably less than or equal to 250 kg / m3, more preferably less than or equal to 200 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, or even more preferably of 50 to 250 kg / m3. The density of the foam can range from 25 to 100 kg / m³, or from 100 to 150 kg / m³, or from 150 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 ASTM D792.

[0187] Preferably, the foam according to the invention has an Asker C hardness of 20 to 70, preferably 20 to 60, more preferably 30 to 50, for example the Asker C hardness can be 20 to 25, or 25 to 30, or 30 to 35, or 35 to 40, or 40 to 45, or 45 to 50, or 50 to 55, or 55 to 60, or 60 to 65, or 65 to 70. The Asker C hardness can be determined at 23°C, after 3 seconds, according to ISO 48-4:2018.

[0188] Advantageously, the size of the cells under the skin of the foam according to the invention is characterized by an average diameter in number less than or equal to 65 pm, of Preferably less than or equal to 55 pm, for example, less than or equal to 50 pm. By "cells under the skin" is meant the cells in the portion of the foam extending from the surface (or skin) of the foam and having a thickness equal to one-quarter of the total thickness of the foam. In particular, the average diameter of the cells under the skin of the foam may be, for example, 15 to 20 pm, or 20 to 25 pm, or 25 to 30 pm, or 30 to 35 pm, or 35 to 40 pm, or 40 to 45 pm, or 45 to 50 pm, or 50 to 55 pm, or 55 to 60 pm, or 60 to 65 pm.

[0189] Preferably, the foam according to the invention has an open cell percentage of 50% or less by number, preferably 45% or less by number, and even more preferably 40% or less by number. In some embodiments, the open cell percentage of the foam is 35% or less by number or 30% or less by number.

[0190] The size of the cells (average diameter by number) under the skin and the percentage of open cells can be measured using the following method. An image of the foam is acquired with a scanning electron microscope (SEM), for example, using a Thermofischer Quanta 250 FEG-SEM microscope. Typical acquisition conditions are preferably as follows: acquisition under vacuum (for example, on the order of 2 x 10⁴ Pa), with an SE (secondary electron detector) or BSE (backscattered electron detector), under an accelerating voltage between 2 kV and 5 kV, with a working distance between 9 and 15 mm, and a spot size between 3 and 5. These parameters and acquisition conditions are optimized to obtain the best image contrast for image analysis using ImageJ software.

[0191] The average diameter of the cells under the skin is measured as follows. Using ImageJ, 50 cells are randomly selected: for this purpose, a grid of 8 rows and 7 columns, evenly spaced and corresponding to approximately 50 intersections, is overlaid on the SEM image, specifically on the portion of the image representing one-quarter of the foam from the foam skin. The cells containing these intersections, or, failing that, those closest to these intersections, are chosen. The area of ​​each selected cell is measured (using the ImageJ software), and the diameter corresponding to the circle of the same area is deduced using the formula:

[0192] [Math.l] Equivalent diameter = ^ / (4 * Ære / 3.1416).

[0193] The average of the 50 diameters is calculated to obtain the average diameter.

[0194] The percentage of open cells is determined as follows. 50 cells are randomly selected as described above. The cells are observed and cells whose wall has an opening are counted as open cells, the others as closed cells. The percentage of open cells is then calculated on the basis of these data.

[0195] Preferably, the foam has a rebound resilience greater than or equal to 50%, more preferably greater than or equal to 55%, and more preferably greater than or equal to 60%. The rebound resilience is measured according to ISO 8307:2007 but using an 18.8 g ball.

[0196] Preferably, this foam exhibits a compression set of 80% or less, and more preferably 75% or less. The compression set (CS) is measured according to the following method: a foam sample is compressed to a strain rate of 50%, at a temperature of 50°C, and for a holding time of 6 hours, after which the stress is released. The residual strain after a recovery time of 30 minutes is measured according to a method adapted from ISO 1856. The compression set, expressed as a percentage, is given by the formula:

[0197] [Math.2] dO — Dr. D.ÆC = -----xl 00 dO - of

[0198] in which dO is the initial thickness of the specimen, de is the thickness of the compressed specimen and dr is the thickness of the specimen after the recovery time.

[0199] Preferably, this foam also exhibits excellent fatigue resistance and flexibility properties.

[0200] Preferably, this foam also exhibits good resistance to tearing, crack initiation and propagation.

[0201] 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 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.

[0202] 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...).

[0203] 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 manufacturing parts in the railway industry, or various parts in the automotive, transportation, electrical and electronic equipment, construction, or manufacturing industries.

[0204] 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

[0205] The foam according to the invention can be prepared by mixing at least one thermoplastic polymer according to the invention (or a thermoplastic polymer composition according to the invention) with a blowing agent (and optionally with one or more additives), and then carrying out a foaming step. Preferably, the foam is prepared without a crosslinking step.

[0206] 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).

[0207] In some embodiments, the blowing agent is mixed with the thermoplastic polymer (or thermoplastic polymer composition) in a molten state. Preferably, the blowing agent is a physical blowing agent. The physical blowing agent may be in liquid or supercritical form and is then converted to a gaseous phase during the foaming step. The foaming may be induced by a pressure drop.

[0208] Advantageously, the foaming is carried out on the mixture of the thermoplastic polymer (or thermoplastic polymer composition) and the blowing agent in the molten state. More preferably, the foam preparation process is an injection foaming or extrusion foaming process.

[0209] More particularly, advantageously, the mixture of the thermoplastic polymer (or thermoplastic polymer composition) and the blowing agent is The material is injected into a mold, and foaming is performed within the mold (injection foaming process). The injection can advantageously be carried out at a temperature within the range of (To + 30°C) to (To + 150°C), for example, within the range of (To + 30°C) to (To + 60°C), or from (To + 60°C) to (To + 90°C), or from (To + 90°C) to (To + 120°C), or from (To + 120°C) to (To + 150°C), the temperature To being as described above. Foaming can be induced by opening the mold, by underdosing, by removing a gas backpressure, or by using a mold equipped with a Variotherm® system. These techniques allow 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: indeed, filling the mold with foam polymer granules and then melting the particles to ensure mechanical strength of the parts without destroying the foam structure are complex operations.

[0210] The process can alternatively be an extrusion foaming process, such as a single-screw or twin-screw extrusion foaming process. Advantageously, the extrusion foaming process comprises a step of supplying the thermoplastic polymer mixture and the blowing agent in a molten state and a step of extruding said mixture, inducing foaming of said mixture directly at the outlet of the extrusion die (the foaming being caused by a pressure drop resulting from the outlet of the extruder).

[0211] In other embodiments, the thermoplastic polymer (or thermoplastic polymer composition) is processed, preferably in a molten state, to create a preform. A blowing agent, in particular a chemical one, may optionally be mixed with the thermoplastic polymer during its processing to form the preform, or beforehand. The preform may be prepared by compression molding, extrusion, injection molding, lamination, or 3D printing processes. Preferably, the preform is produced by extrusion or injection molding. The preform, in its solid state, may be brought into contact with a physical blowing agent in gaseous or supercritical form (in particular, in embodiments in which no blowing agent has been added during, or before, the production of the preform). The physical blowing agent impregnates the solid preform, preferably by means of applying overpressure.Preferably, the foaming is carried out in an autoclave. Preferably, the pressure within the autoclave is maintained between 0.20 and 50 MPa during foaming. Preferably, the temperature during foaming is within the range of (To - 40°C) to (To + 20°C), for example, within the range of (To - 40°C) to (To - 20°C), or of . (To - 20°C) to To, or from To to (To + 20°C), the temperature To being as described above. Advantageously, the foaming of the preform is contained within a mold. Examples

[0212] The following examples illustrate the invention without limiting it.

[0213] The following TPEs have been prepared:

[0214] [Tables 1] TPE No. Class T PE Nature block s PA Mn blocks PA (g / mol) Nature block s PE Mn blocks PE (g / mol) 1 (comparative) PEBA PAU 1000 PTMG 1000 2 (invention) PEBA PAU 1000 PTMG 1000 3 (invention) PEBA PAU 1000 PTMG 1000 4 (comparative) PEBA PAU 800 PTMG 1000 5 (invention) PEBA PAU 800 PTMG 1000 6 (invention) PEBA PAU 800 PTMG 1000 7 (comparative) TPEE - - - - 8 (invention) TPEE - - - -

[0215] These TPEs were prepared in the following way: • TPE No. 1 (comparative): In an autoclave, 19.9 kg of 11-aminoundecanoic acid, 3.09 kg of adipic acid, and 4 kg of water are introduced (loading). The reactor is closed, inert with nitrogen, then stirred and heated under autogenous pressure to 245°C (matter temperature). This temperature is maintained for 1 h at a pressure of 31 bar (gauge). The reactor is then depressurized to atmospheric pressure for 1 h. The mass temperature is 240°C. 20.2 kg of PTMG 1000 are added, and the reactor is then evacuated to a pressure below 15 mbar. 86 g of Irganox 1010 and then 43 g of zirconium tetrabutanolate (catalyst) are added. The viscosity of the reaction mixture is then monitored by measuring the stirring torque. The reaction is stopped when the torque reaches a predefined value. The reactor is then emptied into a water tank and granulated. • TPE No. 2 (invention): TPE No. 2 is prepared according to the same process as TPE No. 1, except that 86 g of pentaerythritol and 3.28 kg of adipic acid (instead of 3.09 kg) are added to the load. • TPE No. 3 (invention): TPE No. 3 is prepared according to the same process as TPE No. 1, except that 129 g of pentaerythritol and 3.37 kg of adipic acid (instead of 3.09 kg) are added to the load. • TPE n°4 (comparative): In an autoclave, 16.6 kg of 11-aminoundecanoic acid, 3.55 kg of adipic acid, and 4 kg of water are introduced (loading). The reactor is closed, inert with nitrogen, then stirred and heated under autogenous pressure to 245°C (matter temperature). This temperature is maintained for 1 h at a pressure of 31 bar (gauge). The reactor is then depressurized to atmospheric pressure for 1 h. The mass temperature is 240°C. 23.1 kg of PTMG 1000 are added, and the reactor is then evacuated to a pressure below 15 mbar. 86 g of Irganox 1010 and then 65 g of zirconium tetrabutanolate are added. The viscosity of the reaction mixture is then monitored by measuring the stirring torque. The reaction is stopped when the torque reaches a predefined value. The reactor is then emptied into a water tank and granulated. • TPE No. 5 (invention): TPE No. 5 is prepared according to the same process as TPE No. 4, except that 86 g of pentaerythritol and 3.73 kg of adipic acid (instead of 3.55 kg) are added to the load. • TPE No. 6 (invention): TPE No. 6 is prepared according to the same process as TPE No. 4, except that 108 g of pentaerythritol and 3.78 kg of adipic acid (instead of 3.55 kg) are added to the load. • TPE n°7 (comparative): copolyetherester marketed by Envalior under the name Arnitel® ECO L400. • TPE No. 8 (invention): TPE No. 8 is prepared by reactive extrusion of TPE No. 7 with the following epoxy compound: a static copolymer of styrene and glycidyl methacrylate. The molar mass by weight (Mw) of the copolymer is 7100 g / mol and its epoxy equivalent weight (EEW) is 485 g / mol. To do this, TPE No. 7 and 2% by mass of said epoxy compound are mixed in a molten state in a twin-screw co-rotating extruder. The equipment used is a ZSK18 extruder with a diameter of 18 mm and a length of 60D. The overall throughput of the extruder is set at 5 kg / h, the screw speed at 400 rpm, and the barrel temperature at 230°C. The product exiting the extruder is granulated in a wet cutting process.

[0216] The tested PEBAs have the following characteristics and properties:

[0217] [Tables2] TPE n° Mw TPE (g / mol) To (°C) Tx (°C) Tx-To (°C) Te (°C) 1 (comparative) 122,000 130.4 128.2 -2.2 89 2 (invention) 173,900 135.2 142.2 7 89.3 3 (invention) 244,700 131.2 140.6 9.4 94.3 4 (comparative) 128 100 118.2 116.9 -1.3 74 5 (invention) 148 700 121.4 124.1 2.7 86 6 (invention) 206 400 124.1 172.6 48.5 97 7 (comparative) 116.3 116.3 0 75.2 8 (invention) 153.8 183.6 29.8

[0218] Rheology measurement was performed using the HR20 device from TA Instruments.

[0219] The temperatures Tx and To were determined, for each of the TPEs No. 1 to 8, in the manner described in the "Thermoplastic Polymer" section of the "Detailed Description" above. The plane-plane rheology curves obtained for TPE No. 2 according to the invention are shown in [Fig. 1] and [Fig. 2].

[0220] The weight average molar masses Mw are expressed in PMMA equivalents and were measured by size exclusion chromatography (or gel permeation chromatography) according to ISO 16014-1 according to the method described above.

[0221] Mousses were prepared from TPE n°1 to 8.

[0222] These foams were manufactured using an ENGEL 160T injection molding machine Victory Injection Machine, with a Trexel Series II type physical blowing agent injection system. The operating parameters are as follows: • Sheath temperature: 170 to 250°C. • Holding time before opening the mold: 0-0.2 s. • Cooling time: 250-320 s. • Mold temperature: 10-18°C. • Mold opening length: up to 15 mm. • Mold: plate mold with dimensions 15 x 110 x 250 mm.

[0223] The foaming agent used is dinitrogen introduced at a level of 0.7% by weight.

[0224] Various properties of the foams obtained were evaluated: • density: according to ASTM D792 standard; • Asker C hardness: according to ISO 48-4:2018, at 23°C, after 15 seconds; • rebound resilience: according to ISO 8307, but with a ball of 18.8 g; • Size of cells under the skin (mean diameter Dmoy): according to the method described above • Percentage of open cells: according to the method described above.

[0225] The properties of the foams are presented in the following table:

[0226] [Tables3] Foam n O TPE used Density (kg / m3) Hardness Rebound resilience D mOy cells under 1% open cells -seed (%) to skin (pm) 1 (comp.) 1 235 69 63 ND ND 2 (inv.) 2 204 67 63 ND ND 3 (inv.) 3 187 66 64 ND ND 4 (comp.) 4 259 65 66 68 50 5 (inv.) 5 240 65 64 ND ND 6 (inv.) 6 209 63 66 49 35 7 (comp.) 7 240 ND ND ND ND 8 (inv.) 8 216 ND ND ND ND

[0227] ND = not determined

[0228] Photographs of foams No. 4 (comparative) and No. 6 (according to the invention) are shown in [Fig.3] and [Fig.4], respectively.

[0229] It is observed that, at similar Asker C hardness, the foams according to the invention exhibit a lower density than foams prepared from polymers for which Tx-To is less than or equal to 0, while retaining excellent rebound resilience.

[0230] In addition, the foams according to the invention have a better cellular structure, in particular smaller cells under the skin and a lower proportion of open cells.

Claims

Demands

1. Thermoplastic polymer, preferably a thermoplastic elastomer, wherein the temperature Tx is greater than the temperature To, Tx and To being measured by determining the curves of the elastic modulus (G') and the loss modulus (G”) as a function of temperature during a plane-plane rheology measurement under 1 Hz cooling, preceded by a holding time of 2 minutes at a temperature TH, the cooling following a ramp of -10°C / min to a temperature T2, then a ramp of -2°C / min, Tx corresponding to the temperature at the intersection of the curves of the elastic modulus (G') and the loss modulus (G”), To corresponding to the temperature at the intersection of the tangent to the curve of the logarithm of the elastic modulus (G') at point Pi and the tangent to the curve of the logarithm of the elastic modulus (G') at point P2, Pi corresponding to the point whose abscissa is less than a temperature T3,where the derivative of the function represented by the log(G') curve is the highest, P2 corresponding to: • the inflection point of the logarithm of the elastic modulus (G') curve when this curve has only one inflection point, or • the inflection point of the logarithm of the elastic modulus (G') curve where the derivative of the function represented by the log(G') curve is the lowest when this curve has several inflection points, the thermoplastic polymer having a crystallization temperature Tc, and • when Tc is less than or equal to 140°C, Ti is 220°C, T2 is 180°C and T3 is 175°C, and • when Tc is greater than 140°C, Ti is Tc + 80°C, T2 is Tc + 40°C and T3 is Tc + 35°C.

2. Thermoplastic polymer according to claim 1, selected from the group consisting of polyamide and polyether block copolymers, thermoplastic polyetheresters, and polyurethanes thermoplastics, preferably aliphatic thermoplastic polyurethanes, and combinations thereof, more preferably from the group consisting of polyamide block and polyether block copolymers, thermoplastic polyetheresters and combinations thereof.

3. Thermoplastic polymer according to claim 1 or 2, which is a copolymer of polyamide blocks and polyether blocks, wherein, preferably: • the polyamide blocks are selected from the group consisting of PA 11, PA 12, PA 6, PA 6.10, PA 6.12, PA 6.13, PA 10.9, PA 10.14, PA 12.9 blocks and mixtures, and copolymers, thereof; and / or • the polyether blocks are selected from the group consisting of polytetrahydrofuran, polyethylene glycol blocks, and mixtures, or copolymers, thereof.

4. Thermoplastic polymer according to any one of claims 1 to 3, wherein the difference between Tx and To (Tx-To) is at least 1, preferably at least 2, more preferably at least 3, even more preferably at least 5, even more preferably at least 10, even more preferably at least 20.

5. Thermoplastic polymer according to any one of claims 1 to 4, being a rigid block and soft block copolymer, wherein the soft blocks have a number average molar mass greater than or equal to 1000 g / mol, preferably greater than or equal to 1800 g / mol, preferably even greater than or equal to 2000 g / mol.

6. Thermoplastic polymer according to any one of claims 1 to 5, being a branched polymer preferably having a weight average molar mass of 80,000 to 260,000 g / mol, preferably of 100,000 to 240,000 g / mol, more preferably of 120,000 to 220,000 g / mol.

7. Thermoplastic polymer according to any one of claims 1 to 6, being a branched polymer comprising branching points made by a residue of at least one branching agent selected from: • polyols comprising at least three hydroxyl groups; • epoxide compounds having a number-average functionality (Efn) greater than 2, preferably greater than or equal to 3; and • combinations thereof.

8. Thermoplastic polymer according to claim 6 or 7, obtained by a preparation process comprising at least one step of mixing a branching agent with precursors of a thermoplastic polymer or one step of mixing a branching agent with a thermoplastic polymer in the molten state, wherein the branching agent is mixed in an amount of 0.05 to 3% by mass, preferably 0.1 to 2.5% by mass, more preferably 0.2 to 2% by mass, relative to the total mass of the branching agent and the precursors of the thermoplastic polymer or of the thermoplastic polymer, and wherein preferably the branching agent is selected from polyols having at least three hydroxyl groups, epoxide compounds having a number-average functionality (Efn) greater than 2, preferably greater than or equal to 3, and combinations thereof.

9. Thermoplastic polymer according to any one of claims 6 to 8, obtained by a preparation process comprising at least one step of mixing a branching agent with precursors of a thermoplastic polymer, wherein the branching agent is a polyol having at least three hydroxyl groups, and wherein the branching agent is mixed in an amount of 0.05 to 1% by mass, preferably 0.1 to 0.6% by mass, more preferably 0.2 to 0.5% by mass, relative to the total mass of the branching agent and the precursors of the thermoplastic polymer.

10. Thermoplastic polymer according to any one of claims 6 to 8, obtained by a preparation process comprising at least one step of mixing a branching agent with a thermoplastic polymer in the molten state, wherein the branching agent is an epoxy compound having a number-average functionality (Efn) greater than 2, preferably greater than or equal to 3, and wherein the branching agent is mixed in an amount of 0.1 to 3% by mass, preferably 0.2 to 2.5% by mass, more preferably 0.5 to 2% by mass, relative to the total mass of the branching agent and the thermoplastic polymer.

11. Composition comprising at least one thermoplastic polymer according to any one of claims 1 to 10, and optionally one or more additives and / or one or more additional polymers.

12. Foam of a thermoplastic polymer according to any one of claims 1 to 10 or of a composition according to claim 11

13. 11. Foam according to claim 12, having a density less than or equal to 800 kg / m3, preferably less than or equal to 600 kg / m3, preferably still less than or equal to 400 kg / m3, more preferably less than or equal to 300 kg / m3, even more preferably less than or equal to 250 kg / m3, even more preferably less than or equal to 200 kg / m3.

14. Foam according to claim 12 or 13, wherein the percentage of open cells is less than or equal to 50% by number, preferably less than or equal to 40% by number.

15. Foam according to any one of claims 12 to 14, wherein the foam cells present in the portion of the foam extending from the surface of the foam and having a thickness equal to one-quarter of the total thickness of the foam, have an average number diameter less than or equal to 65 pm, preferably less than or equal to 55 pm.

16. Foam according to any one of claims 12 to 15, having a rebound resilience greater than or equal to 55%, preferably greater than or equal to 60%.

17. Article made of a foam according to any one of claims 12 to 16 or comprising at least one element made of a foam according to any one of claims 12 to 16, preferably selected from sports shoe soles, balls, gloves, personal protective equipment, automotive and railway parts, construction parts and electrical and electronic equipment parts.

18. A method for manufacturing a foam according to any one of claims 12 to 16, comprising the following steps: • mixing a thermoplastic polymer according to any one of claims 1 to 10, or a composition according to claim 11, in the molten state, optionally with one or more additives, and with a blowing agent; and • foaming this mixture.

19. A process according to claim 18, wherein the mixture which is foamed is in a molten state, the process being an injection foaming or extrusion foaming process.

20. A process according to claim 18 or 19, being an injection foaming process comprising: • injecting the mixture of the thermoplastic polymer, or composition, and the expanding agent into a mold; and • foaming the mixture in the mold; wherein the injection is carried out at a temperature in the range of (To + 30°C) to (To + 150°C).

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