FR3141465A1 - Thermoplastic polyurethane and copolymer foam with polyamide blocks and amine chain-ended polyether blocks - Google Patents

Abstract

The invention relates to a polymer foam comprising at least one thermoplastic polyurethane and at least one copolymer with polyamide blocks and polyether blocks comprising amine chain ends. The invention also relates to a method for preparing such a foam as well as an article comprising such a foam. No figure.

Description

Thermoplastic polyurethane foam and copolymer with polyamide blocks and polyether blocks with amine chain ends Field of invention

The present invention relates to polymeric foams, comprising a thermoplastic polyurethane and a polyamide block and polyether block copolymer with amine chain ends, as well as methods of preparing the same.

Technical background

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

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

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

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

• au moins un polyuréthane thermoplastique, et
• au moins un copolymère à blocs polyamides et à blocs polyéthers comprenant des bouts de chaîne amines, tels que détectés par dosage potentiométrique dans le métacrésol à l’aide d'une solution d’acide perchlorique à 0,02N.

The invention firstly relates to a polymer foam comprising:

• at least one thermoplastic polyurethane, and
• at least one copolymer with polyamide blocks and polyether blocks comprising amine chain ends, as detected by potentiometric assay in metacresol using a 0.02N perchloric acid solution.

In embodiments, at least a portion of the total polyamide block and polyether block copolymer is covalently linked to a thermoplastic polyurethane molecule through a urea functionality.

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

In embodiments, the polyamide block and polyether block copolymer has an NH ₂ amine function concentration, as measured by potentiometric assay in metacresol using a 0.02N perchloric acid solution, of 0.002 meq/g to 0.2 meq/g, preferably 0.005 to 0.1 meq/g.

In embodiments, the amount of polyamide blocks, as measured by proton NMR in a TFA/CDCl ₃ mixture (1/4 v/v), is at least 15% by weight, preferably at least 25% by weight, relative to the total weight of the foam.

In embodiments, the polyamide block and polyether block copolymer comprises at least 30% by weight, preferably at least 40% by weight, of polyamide blocks, relative to the total weight of the copolymer, as measured by proton NMR in a TFA/CDCl ₃ mixture (1/4 v/v).

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

• de 5 à 70 % en poids, de préférence de 15 à 60 % en poids, encore plus préférentiellement de 20 à 45% en poids, de l’au moins un polyuréthane thermoplastique, et
• de 30 à 95 % en poids, de préférence de 40 à 85 % en poids, encore plus préférentiellement de 55 à 80% en poids, de l’au moins un copolymère à blocs polyamides et à blocs polyéthers comprenant des bouts de chaîne amines.

In embodiments, the foam comprises, relative to the total weight of the foam:

• from 5 to 70% by weight, preferably from 15 to 60% by weight, even more preferably from 20 to 45% by weight, of the at least one thermoplastic polyurethane, and
• from 30 to 95% by weight, preferably from 40 to 85% by weight, even more preferably from 55 to 80% by weight, of at least one copolymer with polyamide blocks and polyether blocks comprising amine chain ends.

• les blocs souples sont choisis parmi les blocs polyéthers, les blocs polyesters, les blocs polycarbonates et une combinaison de ceux-ci, de préférence les blocs souples sont choisis parmi les blocs polyéthers, les blocs polyesters, et une combinaison de ceux-ci, et sont plus préférentiellement des blocs de polytétrahydrofurane, de polypropylène glycol et/ou de polyéthylène glycol ; et/ou
• les blocs rigides comprennent des motifs issus du 4,4'-diphénylméthane diisocyanate et/ou du 1,6-hexaméthylène diisocyanate et, de préférence, des motifs issus d’au moins un allongeur de chaine choisi parmi le 1,3-propanediol, le 1,4-butanediol et/ou le 1,6-hexanediol.

In embodiments, the at least one thermoplastic polyurethane is a hard block and soft block copolymer, wherein:

• the flexible blocks are chosen from polyether blocks, polyester blocks, polycarbonate blocks and a combination thereof, preferably the flexible blocks are chosen from polyether blocks, polyester blocks, and a combination thereof, and are more preferably polytetrahydrofuran, polypropylene glycol and/or polyethylene glycol blocks; and/or
• the rigid blocks comprise units derived from 4,4'-diphenylmethane diisocyanate and/or 1,6-hexamethylene diisocyanate and, preferably, units derived from at least one chain extender chosen from 1,3-propanediol, 1,4-butanediol and/or 1,6-hexanediol.

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

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

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

• la fourniture d’une composition polymère comprenant l’au moins un polyuréthane thermoplastique et l’au moins un copolymère à blocs polyamides et à blocs polyéthers comprenant des bouts de chaîne amines ;

• le mélange de ladite composition de polymère avec un agent d’expansion ; et
• le moussage du mélange de composition polymère et d’agent d’expansion.

The invention also relates to a method of manufacturing a foam as described above, comprising the following steps:

• providing a polymer composition comprising at least one thermoplastic polyurethane and at least one polyamide block and polyether block copolymer comprising amine chain ends;

• mixing said polymer composition with a blowing agent; and
• foaming the mixture of polymer composition and blowing agent.

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

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

The invention also relates to an article made of a foam as described above or comprising at least one element made of a foam as described above, preferably chosen from the soles of sports shoes, balls, gloves, personal protective equipment, soles for rails, automobile parts, construction parts and parts of electrical and electronic equipment.

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

This is accomplished by using, for foam formation, a mixture of a thermoplastic polyurethane (TPU) and a polyamide (PA) having amine chain ends (NH ₂ ).

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

Detailed description

The invention is now described in more detail and in a non-limiting manner in the description which follows.

Unless otherwise stated, all percentages are mass percentages.

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

The invention relates firstly to a foam comprising at least one copolymer with polyamide blocks and polyether blocks comprising amine chain ends and at least one thermoplastic polyurethane.

The presence of amine chain ends in the polyamide block and polyether block copolymer can be detected by potentiometric determination using the following method: a sample of material is dissolved in metacresol at 80°C, then the _NH2 functions of this sample are determined by potentiometry using a 0.02N perchloric acid solution.

Polyamide block copolymer and polyether block copolymer (PEBA) with amine chain ends

PEBAs result from the polycondensation of polyamide blocks (rigid or hard blocks) with reactive ends with polyether blocks (flexible or soft blocks) with reactive ends, in particular 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,ω-dihydroxylated polyoxyalkylene blocks called polyetherdiols.

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

Three types of polyamide blocks can be used advantageously.

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

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

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

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

According to a second type, the polyamide blocks result from the condensation of one or more α,ω-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,ω-aminocarboxylic acids include aminocaproic, amino-7-heptanoic, amino-10-decanoic, amino-11-undecanoic and amino-12-dodecanoic acids.

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 from the amino acid residues or the lactam residues.

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

• de la ou des diamines aliphatiques linéaires ou aromatiques ayant X atomes de carbone ;
• du ou des diacides carboxyliques ayant Y atomes de carbone ; et
• du ou des comonomères {Z}, choisis parmi les lactames et les acides α,ω-aminocarboxyliques ayant Z atomes de carbone et les mélanges équimolaires d’au moins une diamine ayant X1 atomes de carbone et d’au moins un diacide carboxylique ayant Y1 atomes de carbones, (X1, Y1) étant différent de (X, Y),
• ledit ou lesdits comonomères {Z} étant introduits dans une proportion pondérale allant avantageusement jusqu’à 50 %, de préférence jusqu’à 20 %, encore plus avantageusement jusqu’à 10 % par rapport à l’ensemble des monomères précurseurs de polyamide ;
• en présence d’un limiteur de chaîne choisi parmi les diacides carboxyliques.

In this case, the polyamide PA blocks are prepared by polycondensation:

• of linear aliphatic or aromatic diamine(s) having X carbon atoms;
• dicarboxylic acid(s) having Y carbon atoms; and
• of the comonomer(s) {Z}, chosen from lactams and α,ω-aminocarboxylic acids having Z carbon atoms and equimolar mixtures of at least one diamine having X1 carbon atoms and at least one dicarboxylic acid having Y1 carbon atoms, (X1, Y1) being different from (X, Y),
• said comonomer(s) {Z} being introduced in a weight proportion advantageously ranging up to 50%, preferably up to 20%, even more advantageously up to 10% relative to all of the polyamide precursor monomers;
• in the presence of a chain limiter chosen from dicarboxylic acids.

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

According to a variant of this third type, the polyamide blocks result from the condensation of at least two α,ω-aminocarboxylic acids or at least two lactams having from 6 to 12 carbon atoms or a lactam and an aminocarboxylic acid not having the same number of carbon atoms in the optional presence of a chain limiter. Examples of aliphatic α,ω-aminocarboxylic acids include aminocaproic, amino-7-heptanoic, amino-10-decanoic, amino-11-undecanoic and amino-12-dodecanoic acids. Examples of lactams include caprolactam, oenantholactam and lauryllactam. Examples of aliphatic diamines include hexamethylenediamine, dodecamethylenediamine and trimethylhexamethylenediamine. Examples of cycloaliphatic diacids include 1,4-cyclohexyldicarboxylic acid. Examples of aliphatic diacids include butanedioic, adipic, azelaic, suberic, sebacic, dodecanedicarboxylic acids, polyoxyalkylene α,ω-diacids and dimerized fatty acids. These dimerized fatty acids correspond to the product of the dimerization reaction of fatty acids (generally containing 18 carbon atoms, often a mixture of oleic and/or linoleic acid); they preferably have a dimer content of at least 98%; preferably they are hydrogenated; it is preferably a mixture comprising from 0 to 15% by weight of C18 monoacids, from 60 to 99% by weight of C36 diacids, and from 0.2 to 35% by weight of C54 or higher triacids or polyacids; these are, for example, the products marketed under the brand name "PRIPOL" by the company "CRODA", or under the brand name EMPOL by the company BASF, or under the brand name Radiacid by the company OLEON. As examples of aromatic diacids, mention may be made of terephthalic (T) and isophthalic (I) acids. Examples of cycloaliphatic diamines include isomers of bis-(4-aminocyclohexyl)-methane (BACM), bis-(3-methyl-4-aminocyclohexyl)-methane (BMACM) and 2-2-bis-(3-methyl-4-aminocyclohexyl)-propane (BMACP), and para-amino-di-cyclohexyl-methane (PACM). Other commonly used diamines include isophoronediamine (IPDA), 2,6-bis-(aminomethyl)-norbornane (BAMN) and piperazine.

• le PA 6.6/6, où 6.6 désigne des motifs hexaméthylènediamine condensée avec l'acide adipique et 6 désigne des motifs résultant de la condensation du caprolactame ;
• le PA 6.6/6.10/11/12, où 6.6 désigne l'hexaméthylènediamine condensée avec l'acide adipique, 6.10 désigne l'hexaméthylènediamine condensée avec l'acide sébacique, 11 désigne des motifs résultant de la condensation de l'acide aminoundécanoïque et 12 désigne des motifs résultant de la condensation du lauryllactame.

Examples of polyamide blocks of the third type include the following:

• PA 6.6/6, where 6.6 denotes hexamethylenediamine units condensed with adipic acid and 6 denotes units resulting from the condensation of caprolactam;
• PA 6.6/6.10/11/12, where 6.6 denotes hexamethylenediamine condensed with adipic acid, 6.10 denotes hexamethylenediamine condensed with sebacic acid, 11 denotes units resulting from the condensation of aminoundecanoic acid and 12 denotes units resulting from the condensation of lauryllactam.

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.

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

Polyether blocks are made up of alkylene oxide units.

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

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

Polyether blocks can also be made up of ethoxylated primary amines. Examples of ethoxylated primary amines include products of the formula:

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

The flexible polyether blocks of PEBA comprise polyoxyalkylene blocks with NH ₂ chain ends, such blocks being obtainable by cyanoacetylation of aliphatic α,ω-dihydroxylated polyoxyalkylene blocks called polyetherdiols. More particularly, the commercial products Jeffamine or Elastamine can be used (for example Jeffamine® D400, D2000, ED 2003, XTJ 542, commercial products of the company Huntsman, also described in documents JP 2004346274, JP 2004352794 and EP 1482011).

The polyetherdiol blocks are thus aminated to be transformed into polyetherdiamines and condensed with polyamide blocks with carboxylic ends. The general method for preparing PEBA copolymers having amide bonds between the PA blocks and the PE blocks is known and described, for example in document EP 1482011. The polyether blocks can also be mixed with polyamide precursors and a diacid chain limiter to prepare polymers with polyamide blocks and polyether blocks having statistically distributed units (one-step process). Polyetherdiols with OH chain ends can be present with the aminated polyetherdiols during their condensation with the polyamide blocks. These polyetherdiols with OH chain ends can be condensed with polyamide blocks with carboxylic ends, forming ester bonds between the PA blocks and the PE blocks (the products obtained being polyetheresteramides).

Preferably, for the preparation of PEBAs, polyetherdiol blocks are copolycondensed with polyamide blocks with carboxylic ends.

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

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

The PEBAs that can be used in the invention include copolymers comprising a single polyamide block and a single polyether block, but also copolymers comprising three, four (or even more) different blocks chosen from those described in the present description, provided that these blocks comprise at least one polyamide block and one polyether block. In addition, the PEBAs that can be used in 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.

For example, the copolymer may be a segmented block copolymer comprising three different types of blocks (or " triblock "), which results from the condensation of several of the blocks described above. Said triblock may for example be a copolymer comprising a polyamide block, a polyester block and a polyether block or a copolymer comprising a polyamide block and two different polyether blocks, for example a PEG block and a PTMG block.

Particularly preferred PEBA copolymers in the context of the invention are copolymers comprising blocks: PA 10 and PEG; PA 10 and PTMG; PA 11 and PEG; PA 11 and PTMG; PA 12 and PEG; PA 12 and PTMG; PA 6.10 and PEG; PA 6.10 and PTMG; PA 6 and PEG; PA 6 and PTMG; PA 6.12 and PEG; PA 6.12 and PTMG.

The number-average molar mass of the polyamide blocks in the PEBA copolymer is preferably from 400 to 20,000 g/mol, more preferably from 500 to 10,000 g/mol. In embodiments, the number average molar mass of the polyamide blocks in the PEBA copolymer is from 400 to 500 g/mol, or 500 to 600 g/mol, or 600 to 1000 g/mol, or 1000 to 1500 g/mol, or 1500 to 2000 g/mol, or 2000 to 2500 g/mol, or 2500 to 3000 g/mol, or 3000 to 3500 g/mol, or 3500 to 4000 g/mol, or 4000 to 5000 g/mol, or 5000 to 6000 g/mol, or 6000 to 7000 g/mol, or 7000 to 8000 g/mol, or 8000 to 9000 g/mol, or 9000 to 10000 g/mol, or 10000 to 11000 g/mol, or 11000 to 12000 g/mol, or 12000 to 13000 g/mol, or 13000 to 14000 g/mol, or 14000 to 15000 g/mol, or 15000 to 16000 g/mol, or 16000 to 17000 g/mol, or 17000 to 18000 g/mol, or 18000 to 19000 g/mol, or 19000 to 20000 g/mol.

The number-average molar mass of the polyether blocks is preferably from 100 to 6000 g/mol, more preferably from 200 to 3000 g/mol. In embodiments, the number average molar mass of the polyether blocks is from 100 to 200 g/mol, or from 200 to 500 g/mol, or from 500 to 800 g/mol, or from 800 to 1000 g/mol, or from 1000 to 1500 g/mol, or from 1500 to 2000 g/mol, or from 2000 to 2500 g/mol, or from 2500 to 3000 g/mol, or from 3000 to 3500 g/mol, or from 3500 to 4000 g/mol, or from 4000 to 4500 g/mol, or from 4500 to 5000 g/mol, or from 5000 to 5500 g/mol, or from 5500 to 6000 g/mol.

The number-average molar mass is fixed by the chain limiter content. It can be calculated according to the relation:

M _n = n _monomer x MW _{repeating unit} / n _{chain limiter} + MW _{chain limiter}

In this formula, n _monomer represents the number of moles of monomer, n _{chain limiter} represents the number of moles of excess diacid limiter, MW _{repeat unit} represents the molar mass of the repeat unit, and MW _{chain limiter} represents the molar mass of the excess diacid.

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

Advantageously, the amount of polyamide blocks in the PEBA is at least 10% by weight and preferably at least 20% by weight (relative to the total weight of the PEBA). Even more advantageously, the amount of polyamide blocks in the PEBA is at least 30% by weight, more preferably at least 40% by weight, even more preferably at least 50% by weight. The amount of polyamide blocks in the PEBA may be from 10 to 95% by weight (the amount of polyether blocks preferably being from 5 to 90% by weight), preferably from 30 to 90% by weight (the amount of polyether blocks preferably being from 10 to 70% by weight), more preferably from 40 to 85% by weight (the amount of polyether blocks preferably being from 15 to 60% by weight). More particularly, the amount of polyamide blocks in the PEBA may be from 10 to 30% by weight (the amount of polyether blocks preferably being from 70 to 90% by weight), or from 30 to 40% by weight (the amount of polyether blocks preferably being from 60 to 70% by weight), or from 40 to 50% by weight (the amount of polyether blocks preferably being from 50 to 60% by weight), or from 50 to 60% by weight (the amount of polyether blocks preferably being from 40 to 50% by weight), or from 60 to 70% by weight (the amount of polyether blocks preferably being from 30 to 40% by weight), or from 70 to 80% by weight (the amount of polyether blocks preferably being from 20 to 30% by weight), or from 80 at 95% by weight (the amount of polyether blocks preferably being 5 to 20% by weight). The amount of polyamide blocks in the PEBA can be determined by proton NMR (1H) in a TFA/CDCl ₃ mixture (1/4 v/v), preferably using a Brucker AM 500 spectrometer, according to the protocol described in the article “Synthesis and characterization of poly(copolyethers-block-polyamides) - II. Characterization and properties of the multiblock copolymers”, Maréchal et al. , Polymer , Volume 41, 2000, 3561–3580 (the assignment of the signals being carried out using Figure 5 of said article). These amounts make it possible to obtain a foam having a lower density, greater flexibility and better rebound resilience.

Advantageously, PEBA has a concentration depending on NH₂from 0.01 meq/g to 1 meq/g, preferably from 0.02 meq/g to 0.4 meq/g. The PEBA can have a concentration depending on NH₂from 0.01 to 0.015 meq/g, or from 0.015 to 0.02 meq/g, or from 0.02 to 0.025 meq/g, or from 0.025 to 0.03 meq/g, or from 0.03 to 0.035 meq/g, or from 0.035 to 0.04 meq/g, or from 0.04 to 0.045 meq/g, or from 0.045 to 0.05 meq/g, or from 0.05 to 0.06 meq/g, or from 0.06 to 0.07 meq/g, or from 0.07 to 0.08 meq/g, or from 0.08 to 0.09 meq/g, or from 0.09 to 0.1 meq/g, or from 0.1 to 0.2 meq/g, or 0.2 to 0.3 meq/g, or 0.3 to 0.4 meq/g, or 0.4 to 0.5 meq/g, or 0.5 to 0.6 meq/g, or 0.6 to 0.7 meq/g, or 0.7 to 0.8 meq/g, or 0.8 to 0.9 meq/g, or 0.9 to 1 meq/g. Concentration as a function of NH₂can be measured using a potentiometric assay according to the following method: a sample of foam is dissolved in metacresol at 80°C, then the NH functions₂of this sample are measured by potentiometry with a 0.02N perchloric acid solution.

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

PEBA may also comprise hydroxyl (OH) chain ends (e.g. from the condensation of polyetherdiols with OH chain ends with polyamide blocks with carboxylic ends). In particular, PEBA may have a concentration in OH function (i.e. in hydroxyl chain ends) from 0.002 to 0.2 meq/g, preferably from 0.005 to 0.05 meq/g. The concentration in OH function can be determined by proton NMR (1H) in a TFA/CDCl mixture₃(1/4 v/v), preferably using a Brucker AM 500 spectrometer, according to the protocol described in the article “Synthesis and characterization of poly(copolyethers-block-polyamides) - II. Characterization and properties of the multiblock copolymers”, Maréchalet al.,Polymer, Volume 41, 2000, 3561–3580 (signal assignment being performed using Figure 5 of said article).

Advantageously, the polyamide block and polyether block copolymer has a Shore D hardness greater than or equal to 30. Preferably, the copolymer used in the invention has an instantaneous hardness of 65 Shore A to 80 Shore D, more preferably of 75 Shore A to 65 Shore D, more preferably of 80 Shore A to 55 Shore D. The hardness measurements can be carried out according to the ISO 7619-1 standard.

Thermoplastic polyurethane (TPU)

Thermoplastic polyurethane is a copolymer of hard blocks and soft blocks.

In general, in this text, a " rigid block " means a block that has a melting point greater than 50°C. The presence of a melting point can be determined by differential scanning calorimetry, according to ISO 11357-3 Plastics - Differential scanning calorimetry (DSC) Part 3. A " soft block " means a block that has 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.

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 consisting of units derived from polyisocyanates and chain extenders while the flexible blocks mainly comprise units derived from compounds reactive with isocyanate having a molar mass of between 0.5 and 100 kg/mol, preferably polyols.

The polyisocyanate may be aliphatic, cycloaliphatic, araliphatic and/or aromatic. Preferably, the polyisocyanate is aliphatic, or aromatic. More preferably, the polyisocyanate is aliphatic. Preferably, the polyisocyanate is a diisocyanate.

Advantageously, the polyisocyanate is selected from the group consisting of tri-, tetra-, penta-, hexa-, hepta- and/or octamethylene diisocyanate, 2-methyl-pentamethylene 1,5-diisocyanate, 2-ethyl-butylene-1,4-diisocyanate, 1,5-pentamethylene diisocyanate, 1,4-butylene diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (isophorone diisocyanate, IPDI), 1,4-bis(isocyanatomethyl)cyclohexane, 1,3-bis(isocyanatomethyl)cyclohexane (HXDI), 2,4-paraphenylene diisocyanate (PPDI), 2,4-tetramethylene xylene diisocyanate (TMXDI), 4,4'-, 2,4'- and/or 2,2'-dicyclohexylmethane diisocyanate (H12 MDI), 1,4-cyclohexane diisocyanate, 1-methyl-2,4- and/or 1-methyl-2,6-cyclohexane diisocyanate, 2,2'-, 2,4'- and/or 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), 2,4- and/or 2,6-toluene diisocyanate (TDI), diphenylmethane diisocyanate, 3,3'-dimethyl-diphenyl diisocyanate, 1,2-diphenylethane diisocyanate, phenylene diisocyanate, methylene bis (4-cyclohexylisocyanate) (HMDI) and mixtures thereof.

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

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

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

Preferably, the isocyanate-reactive compound (preferably a polyol) has a number average molar mass of 500 to 100,000 g/mol. The isocyanate-reactive compound may have a number average molar mass of 500 to 8,000 g/mol, more preferably of 700 to 6,000 g/mol, more particularly of 800 to 4,000 g/mol. In embodiments, the isocyanate-reactive compound has a number average molar mass of 500 to 600 g/mol, or 600 to 700 g/mol, or 700 to 800 g/mol, or 800 to 1000 g/mol, or 1000 to 1500 g/mol, or 1500 to 2000 g/mol, or 2000 to 2500 g/mol, or 2500 to 3000 g/mol, or 3000 to 3500 g/mol, or 3500 to 4000 g/mol, or 4000 to 5000 g/mol, or 5000 to 6000 g/mol, or 6000 to 7000 g/mol, or 7000 to 8000 g/mol. to 8000 g/mol, or from 8000 to 10000 g/mol, or from 10000 to 15000 g/mol, or from 15000 to 20000 g/mol, or from 20000 to 30000 g/mol, or from 30000 to 40000 g/mol, or from 40000 to 50000 g/mol, or from 50000 to 60000 g/mol, or from 60000 to 70000 g/mol, or from 70000 to 80000 g/mol, or from 80000 to 100000 g/mol. The number average molar mass can be determined by GPC, preferably according to ISO 16014-1:2012.

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

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

As polyester polyol, mention may be made of polycaprolactone polyols and/or copolyesters based on one or more carboxylic acids chosen from adipic acid, succinic acid, pentanedioic acid and/or sebacic acid and one or more alcohols chosen from 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol and/or polytetrahydrofuran. More particularly, the copolyester may be based on adipic acid and a mixture of 1,2-ethanediol and 1,4-butanediol, or the copolyester may be based on adipic acid, succinic acid, pentanedioic acid, sebacic acid or mixtures thereof, and polytetrahydrofuran (tetramethylene glycol), or the copolyester may be a mixture of these copolyesters.

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

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

(I)

in which R is preferably a C ₂ -C ₄ alkylene, R' is preferably a C ₁ -C ₄ alkyl and each of n, m and p independently represents an integer preferably between 0 and 50, m being more preferably from 1 to 50, even more preferably from 2 to 50. Preferably, the polysiloxane has the following formula (II):

(II)

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

(III)

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

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

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

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

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

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

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

Advantageously, a catalyst is used to synthesize the thermoplastic polyurethane. The catalyst makes it possible to accelerate the reaction between the NCO groups of the polyisocyanate and the isocyanate-reactive compound (preferably with the hydroxyl groups of the isocyanate-reactive compound) and with the chain extender.

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

More preferably, the catalyst is selected from the group consisting of tin dioctoate, bismuth decanoate, titanium acid esters and mixtures thereof. More preferably, the catalyst is tin dioctoate.

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

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

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

The content of rigid blocks in the TPU is preferably less than or equal to 90% by weight and more preferably less than or equal to 80% by weight (relative to the total mass of the TPU). More advantageously, the content of rigid blocks in the TPU is from 30 to 60% by weight (the amount of flexible blocks being from 40 to 70% by weight). More particularly, the content of rigid blocks in the TPU may be 10 to 20 wt% (the amount of soft blocks being 80 to 90 wt%), or 20 to 30 wt% (the amount of soft blocks being 70 to 80 wt%), or 30 to 40 wt% (the amount of soft blocks being 60 to 70 wt%), or 40 to 50 wt% (the amount of soft blocks being 50 to 60 wt%), or 50 to 60 wt% (the amount of soft blocks being 40 to 50 wt%), or 60 to 70 wt% (the amount of soft blocks being 30 to 40 wt%), or 70 to 80 wt% (the amount of soft blocks being 20 to 30 wt%). weight), or 80 to 90% by weight (the amount of soft blocks being 10 to 20% by weight). These amounts make it possible to obtain a foam with a lower density, greater flexibility and better rebound resilience. The content of hard blocks, expressed as a percentage, is defined as follows:

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

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

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

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

Advantageously, the TPU has a melt flow index (or MFI) of 10 to 100 g/10 min, preferably 25 to 80 g/10 min, more preferably 35 to 65 g/10 min. In particular, the melt flow index of the TPU may be 10 to 25 g/10 min, or 25 to 35 g/10 min, or 35 to 45 g/10 min, or 45 to 55 g/10 min, or 55 to 65 g/10 min, or 65 to 80 g/10 min, or 80 to 100 g/10 min. The melt flow index is measured at 200°C under a load of 10 kg, according to standard ASTM D1238.

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

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

Very advantageously, the TPU is not crosslinked.

TPU and PEBA foam

Advantageously, the amount of polyamide blocks in the foam is at least 15% by weight, preferably at least 20% by weight, more preferably at least 25% by weight, more preferably at least 30% by weight, more preferably at least 35% by weight (relative to the total weight of the foam). The amount of polyamide blocks in the foam can be determined by proton NMR in a TFA/CDCl ₃ mixture (1/4 v/v), preferably using a Brucker AM 500 spectrometer, according to the protocol described in the article "Synthesis and characterization of poly(copolyethers-block-polyamides) - II. Characterization and properties of the multiblock copolymers", Maréchal et al. , Polymer , Volume 41, 2000, 3561–3580 (the assignment of the signals being carried out using FIG. 5 of said article).

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

The amounts listed above result in a lower density, greater softness and better rebound resilience of the foam.

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

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

The molar ratio of the urethane functions to the NH ₂ amine functions of the assembly consisting of at least one copolymer with polyamide blocks and polyether blocks comprising amine chain ends and at least one thermoplastic polyurethane, in the foam according to the invention, may be from 15 to 350, preferably from 25 to 250, even more preferably from 40 to 200. The concentrations of amine functions and urethane functions can be determined by 13C NMR in DMSO D6 as described in the article below: “Reactivity of isocyanates with urethanes: Conditions for allophanate formation”, Lapprand et al. , Polymer Degradation and Stability , Volume 90, No. 2, 2005, 363-373.

Advantageously, the TPU and PEBA foam according to the invention comprises at least part of the total of polyamide block and polyether block copolymer covalently linked to thermoplastic polyurethane by a urea function.

Preferably, the foam according to the invention has a urea function concentration of 0.001 meq/g to 0.1 meq/g, preferably of 0.003 meq/g to 0.08 meq/g, more preferably of 0.005 meq/g to 0.05 meq/g. The urea function concentration in the foam may be from 0.001 to 0.005 meq/g, or from 0.005 to 0.01 meq/g, or from 0.01 to 0.02 meq/g, or from 0.02 to 0.03 meq/g, or from 0.03 to 0.04 meq/g, or from 0.04 to 0.05 meq/g, or from 0.05 to 0.08 meq/g, or from 0.08 to 0.1 meq/g. The urea function concentration can be measured by 13C NMR in DMSO D6, as described in the article "Reactivity of isocyanates with urethanes: Conditions for allophanate formation", Lapprand et al. , Polymer Degradation and Stability , Volume 90, No. 2, 2005, 363-373. The signals corresponding to the carbonyl groups of urethane and urea functions are integrated in order to determine a urea function rate, and the assignment of the signals is made using Figure 6 of said article.

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

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

Alternatively, the foam may comprise one or more additives, for example ethylene vinyl acetate copolymers or EVA (for example those marketed under the name Evatane® by SK Chemical), or ethylene acrylate copolymers, or ethylene alkyl(meth)acrylate copolymers, for example those marketed under the name Lotryl® by SK Chemical. These additives may allow the hardness of the foamed part to be adjusted, its appearance and its comfort. Other additives suitable for the invention include pigments (such as TiO ₂ and other compatible colored pigments), adhesion promoters (to improve the adhesion of the foam to other materials), fillers (e.g., calcium carbonate, barium sulfate and/or silicon oxide), nucleating agents (particularly in pure or concentrated form, e.g., CaCO ₃ , ZnO, SiO ₂ , or combinations of two or more thereof), rubbers (to improve rubber elasticity, such as natural rubber, SBR, polybutadiene and/or ethylene propylene terpolymers), stabilizers (e.g., antioxidants, UV absorbers and/or flame retardants), processing aids (e.g., stearic acid), antioxidants, including phenolic antioxidants such as IRGANOX from Ciba Geigy Inc. The additives may be present in a content of 0 to 30% by weight, preferably 0.1 to 20% by weight, more preferably 0.2% to 10% by weight, relative to the total weight of the foam.

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

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

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

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

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

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

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

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

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

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

Preparation of the mousse

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

The blowing agent may be a chemical or physical agent, or may also consist of any type of hollow object or any type of expandable microsphere. Preferably, it is a physical agent, such as for example dinitrogen or carbon dioxide, or a hydrocarbon, chlorofluorocarbon, hydrochlorocarbon, hydrofluorocarbon or hydrochlorofluorocarbon (saturated or unsaturated) or a mixture thereof. For example, butane or pentane may be used. Also preferably, it may also be a chemical agent such as for example azodicarbonamide or mixtures based on citric acid and sodium hydrogen carbonate (NaHCO ₃ ) (such as the product from the Hydrocerol® range from Clariant).

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

Advantageously, the mixture of the polymer composition and the blowing agent is injected into a mold and foaming is carried out in the mold. Foaming can be caused by opening the mold, by underdosing, by applying gas counter-pressure, by a breathable mold or by a mold equipped with a Variotherm® system. These techniques make it possible to directly produce three-dimensional foamed objects with complex geometries. They are also relatively simple techniques to implement, particularly compared to certain foamed particle fusion processes: in fact, filling the mold with foamed polymer granules and then melting the particles to ensure mechanical strength of the parts without destroying the structure of the foam are complex operations.

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

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

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

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

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

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

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

The step of blending the TPU with the PEBA may comprise blending the polyamide block copolymer and the polyether block copolymer comprising amine chain ends and the thermoplastic polyurethane, in the molten state, with additives.

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

• introduction dans un réacteur des précurseurs du polyuréthane thermoplastique (c’est-à-dire au moins un polyisocyanate, au moins un allongeur de chaine, et optionnellement au moins un composé réactif avec l’isocyanate) ;
• introduction dans le réacteur du copolymère à blocs polyamides et à blocs polyéthers comprenant des bouts de chaîne amines ; et
• synthèse du polyuréthane thermoplastique dans le réacteur en présence du copolymère à blocs polyamides et à blocs polyéthers comprenant des bouts de chaîne amines, de sorte à obtenir la composition polymère.

Thus, the preparation process may comprise the steps of:

• introduction into a reactor of the precursors of thermoplastic polyurethane (i.e. at least one polyisocyanate, at least one chain extender, and optionally at least one compound reactive with the isocyanate);
• introduction into the reactor of the copolymer with polyamide blocks and polyether blocks comprising amine chain ends; and
• synthesis of thermoplastic polyurethane in the reactor in the presence of the copolymer with polyamide blocks and polyether blocks comprising amine chain ends, so as to obtain the polymer composition.

Such a preparation method allows the reaction of the NH ₂ amine functions of a portion of the polyamide block and polyether block copolymer with the isocyanate functions of a portion of the polyisocyanate during the synthesis of the thermoplastic polyurethane, leading to the formation of covalent bonds between the polyamide block and polyether block copolymer and the thermoplastic polyurethane, which improves the compatibility between the polyamide block and polyether block copolymer and the thermoplastic polyurethane.

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

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

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

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

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

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

Claims (16)

Polymer foam comprising:

• at least one thermoplastic polyurethane, and
• at least one copolymer with polyamide blocks and polyether blocks comprising amine chain ends, as detected by potentiometric assay in metacresol using a 0.02N perchloric acid solution.

The foam of claim 1, wherein at least a portion of the total polyamide block and polyether block copolymer is covalently bonded to a thermoplastic polyurethane molecule by a urea function. Foam according to claim 2, in which the concentration of urea function, as measured by 13C NMR in DMSO D6, is from 0.001 meq/g to 0.1 meq/g, more preferably from 0.003 meq/g to 0.08 meq/g, more preferably from 0.005 meq/g to 0.05 meq/g. Foam according to one of claims 1 to 3, in which the copolymer with polyamide blocks and polyether blocks has a concentration of NH ₂ amine function, as measured by potentiometric assay in metacresol using a 0.02N perchloric acid solution, of 0.002 meq/g to 0.2 meq/g, preferably of 0.005 to 0.1 meq/g. Foam according to one of claims 1 to 4, in which the quantity of polyamide blocks, as measured by proton NMR in a TFA/CDCl ₃ mixture (1/4 v/v), is at least 15% by weight, preferably at least 25% by weight, relative to the total weight of the foam. Foam according to one of claims 1 to 5, in which the copolymer with polyamide blocks and polyether blocks comprises at least 30% by weight, preferably at least 40% by weight, of polyamide blocks, relative to the total weight of the copolymer, as measured by proton NMR in a TFA/CDCl ₃ mixture (1/4 v/v). Foam according to one of claims 1 to 6, in which the at least one thermoplastic polyurethane is a copolymer with rigid blocks and flexible blocks, the content of rigid blocks in the thermoplastic polyurethane, as measured by proton NMR in DMSO D6, being less than or equal to 90% by weight, more preferably less than or equal to 80% by weight, more preferably from 30 to 60% by weight. Foam according to one of claims 1 to 7, comprising, relative to the total weight of the foam:

• from 5 to 70% by weight, preferably from 15 to 60% by weight, even more preferably from 20 to 45% by weight, of the at least one thermoplastic polyurethane, and
• from 30 to 95% by weight, preferably from 40 to 85% by weight, even more preferably from 55 to 80% by weight, of at least one copolymer with polyamide blocks and polyether blocks comprising amine chain ends.

Foam according to one of claims 1 to 8, in which the at least one thermoplastic polyurethane is a copolymer with rigid blocks and soft blocks, in which:

• the flexible blocks are chosen from polyether blocks, polyester blocks, polycarbonate blocks and a combination thereof, preferably the flexible blocks are chosen from polyether blocks, polyester blocks, and a combination thereof, and are more preferably polytetrahydrofuran, polypropylene glycol and/or polyethylene glycol blocks; and/or
• the rigid blocks comprise units derived from 4,4'-diphenylmethane diisocyanate and/or 1,6-hexamethylene diisocyanate and, preferably, units derived from at least one chain extender chosen from 1,3-propanediol, 1,4-butanediol and/or 1,6-hexanediol.

Foam according to one of claims 1 to 9, in which the polyamide blocks of the copolymer with polyamide blocks and polyether blocks comprising amine chain ends are blocks of polyamide 11, polyamide 12, polyamide 10, polyamide 6, polyamide 6.10, polyamide 6.12, polyamide 6.13, polyamide 10.9, polyamide 10.10, polyamide 10.12 and/or polyamide 12.9, preferably polyamide 11, polyamide 12, polyamide 6, polyamide 6.12, polyamide 6.13, polyamide 10.9 and/or polyamide 12.9; and/or the polyether blocks of the polyamide block copolymer and the polyether block copolymer comprising amine chain ends are blocks of polyethylene glycol and/or polypropylene glycol and/or polytetrahydrofuran. Foam according to one of claims 1 to 10, having a density, as measured at 23°C according to standard ISO 1183-1, less than or equal to 800 kg/m ³ , preferably less than or equal to 400 kg/m ³ , more preferably less than or equal to 300 kg/m ³ , even more preferably less than or equal to 230 kg/m ³ . Foam according to one of claims 1 to 11, having an Asker hardness C, as measured at 23°C according to ISO 7619-1, of 20 to 90, preferably of 25 to 70. Method of manufacturing a foam according to one of claims 1 to 12, comprising the following steps:

• providing a polymer composition comprising at least one thermoplastic polyurethane and at least one polyamide block and polyether block copolymer comprising amine chain ends;

• mixing said polymer composition with a blowing agent; and
• foaming the mixture of polymer composition and blowing agent.

The method of claim 13, wherein the blowing agent is mixed with the polymer composition in the molten state, the foaming of the mixture being preferably carried out in a mold. A method according to claim 13 wherein the blowing agent is a physical blowing agent and is mixed with the polymer composition in the form of a solid preform, the foaming of the mixture being preferably carried out in an autoclave. Article made of a foam according to one of claims 1 to 12 or comprising at least one element made of a foam according to one of claims 1 to 12, preferably chosen from the soles of sports shoes, balls, gloves, personal protective equipment, soles for rails, automobile parts, construction parts and parts of electrical and electronic equipment.