Foamable polymer composition comprising a branched copolymer containing polyamide blocks and polyether blocks

Abstract

The present invention relates to a foamable composition, which comprises an ethylene-vinyl acetate (EVA) copolymer and / or an ethylene-(meth) alkyl acrylate copolymer and a branched copolymer containing a polyamide block and a polyether block, a method for making the composition, and uses thereof. The present invention also relates to foam, a method for making the foam, and uses of the foam.

Description

Technical Field

[0001] The present invention relates to a foamable composition comprising an ethylene-vinyl acetate (EVA) copolymer and / or a copolymer of ethylene and an alkyl (meth)acrylate, and a branched copolymer containing a polyamide block and a polyether block, a method for preparing the composition, and the use of the composition. The present invention also relates to a foam, a method for producing the foam, and the use of the foam. Background Art

[0002] Various foams based on EVA copolymers are mainly used in the field of sports equipment, such as soles or sole parts, gloves, rackets or golf balls, personal protection items, especially personal protection items for practicing sports (jackets, inner parts of helmets, shells, etc.). This application requires a set of special physical properties that ensure resilience, low compression set, and the ability to withstand repeated impacts without deformation and to return to the original shape.

[0003] There are a large number of cross-linked EVA foams developed with chemical blowing agents for footwear applications. However, these EVA foams have limitations in terms of flexibility, resilience, relatively narrow operating temperature range, relatively low stretchability, and unsatisfactory durability. In addition, no matter what method is used to obtain these foams, they all suffer from significant shrinkage.

[0004] Document WO 2013 / 192581 describes EVA foams comprising a polyolefin elastomer and an olefin block copolymer.

[0005] Document US2017 / 0267849 describes a pre-foamed composition comprising a partially hydrogenated thermoplastic elastomer block copolymer, an olefin block copolymer and EVA. The partially hydrogenated thermoplastic elastomer block copolymer is an ABA or AB copolymer, wherein the A block comprises a styrene unit, and the B block is a random copolymer of ethylene and an olefin.

[0006] However, it has proven difficult to obtain foams that combine the properties of low density and good resilience. This is because, in general, with an increase in density, an improvement in mechanical properties is observed, and vice versa, a decrease in density negatively affects mechanical properties, in particular elasticity.

[0007] There is a need to provide compositions making it possible to obtain lighter polymer foams having reduced shrinkage after foam shaping and having better recovery properties while maintaining good stiffness. Summary of the invention

[0008] The present invention firstly relates to a composition comprising:

[0009] - copolymer (a), said copolymer (a) being selected from ethylene-vinyl acetate (EVA) copolymers, copolymers of ethylene and alkyl (meth)acrylates, and / or mixtures thereof,

[0010] - branched copolymers (b) containing polyamide blocks and polyether blocks (branched PEBA copolymers),

[0011] - a cross-linking agent, preferably a peroxide.

[0012] According to one embodiment, the polymer composition according to the invention comprises from 30% to 99.9% by weight, typically from 50% to 99.9% by weight, preferably from 60% to 99.9% by weight, more preferably from 70% to 99% by weight, of copolymer (a), relative to the total weight of the foam.

[0013] According to one embodiment, the composition comprises from 0.1% to 50% by weight, preferably from 0.1% to 40% by weight, of branched PEBA copolymer (b), relative to the total weight of the composition. Preferably, the composition comprises from 0.1% to 30% by weight, or from 0.5% to 30% by weight, or from 1% to 25% by weight, or from 1% to 20% by weight, of PEBA copolymer (b), relative to the total weight of the composition.

[0014] The composition generally comprises from 0.01% to 2% by weight of a crosslinking agent, preferably a peroxide, relative to the total weight of the composition.

[0015] According to one embodiment, the composition comprises from 0.1% to 20% by weight of additives relative to the total weight of the composition.

[0016] According to one embodiment, the composition further comprises from 0.5% to 10% by weight, preferably from 0.5% to 8% by weight, of a blowing agent, relative to the total weight of the composition.

[0017] According to one embodiment, the composition of the invention may additionally comprise a polyolefin (c) and / or a thermoplastic elastomeric polymer (d).

[0018] According to one embodiment, the composition of the invention comprises:

[0019] - copolymer (a), said copolymer (a) being selected from ethylene-vinyl acetate (EVA) copolymers, copolymers of ethylene and alkyl (meth)acrylates, and / or mixtures thereof,

[0020] a branched copolymer (b) comprising polyamide blocks and polyether blocks, said copolymer (b) having a number-average functionality (Efn) greater than 2, preferably greater than or equal to 3,

[0021] - optionally polyolefins (c) and / or thermoplastic elastomeric polymers (d),

[0022] - a cross-linking agent, preferably a peroxide.

[0023] According to one embodiment, the composition comprises:

[0024] 30% to 99.9% by weight, typically 50% to 99.9% by weight, preferably 60% to 99.9% by weight, more preferably 70% to 99.9% by weight of a copolymer (a) selected from ethylene-vinyl acetate (EVA) copolymers, copolymers of ethylene and alkyl (meth)acrylates, and / or mixtures thereof,

[0025] 0.1% to 40% by weight, preferably 0.1% to 30% by weight, of a branched copolymer (b) containing polyamide blocks and polyether blocks, said copolymer (b) having a number-average functionality (Efn) greater than 2, preferably greater than or equal to 3,

[0026] 0% to 50% by weight, preferably 0.1% to 40% by weight, or 0.1% to 30% by weight, or 0.1% to 20% by weight, of polyolefin (c) and / or thermoplastic elastomeric polymer (d), relative to the total weight of the composition,

[0027] - 0.01 to 2% by weight of a crosslinking agent, preferably a peroxide, and

[0028] The total amount amounts to 100% by weight.

[0029] Preferably, the composition comprises from 0.1% to 50% by weight, preferably from 0.1% to 40% by weight, or from 0.1% to 30% by weight, or from 0.1% to 20% by weight of polyolefin (c) and / or thermoplastic elastomeric polymer (d), relative to the total weight of the composition.

[0030] The polyolefin (c) may be functionalized or non-functionalized or a mixture of at least one functionalized and / or at least one non-functionalized. The polyolefin (c) is preferably a functionalized polyolefin (c1).

[0031] The thermoplastic elastomeric polymer (d) can generally be selected from copolymers containing polyester blocks and polyether blocks, linear copolymers containing polyamide blocks and polyether blocks (PEBA), polyurethanes, olefinic thermoplastic elastomers or olefinic block copolymers, styrene-diene block copolymers, and / or mixtures thereof.

[0032] The present invention also relates to a method for preparing the composition as described above, the method comprising:

[0033] (i) providing a mixture comprising:

[0034] - copolymer (a),

[0035] - copolymer (b),

[0036] - a crosslinking agent, preferably a peroxide, and

[0037] - optionally a polyolefin (c), a thermoplastic elastomeric polymer (d) and at least one additive;

[0038] (ii) A step of shaping the mixture by injection molding, compression / molding or extrusion.

[0039] The above steps can be carried out separately or simultaneously. The steps of the preparation method can be carried out in the same equipment, for example in a mixer or an extruder.

[0040] The composition according to the invention may be in the form of granules, rods, extruded sheets or extruded or injection-moulded parts.

[0041] According to one embodiment, step (i) is carried out by mixing, typically in the molten state, as follows:

[0042] - 30% to 99.9% by weight, typically 50% to 99.9% by weight, preferably 60% to 99.9% by weight, of copolymer (a);

[0043] - 0.1 to 50% by weight, typically 0.1 to 40% by weight, preferably 0.1 to 30% by weight, of copolymer (b);

[0044] - 0 to 50% by weight of polyolefins (c) and / or thermoplastic elastomeric polymers (d);

[0045] - 0% to 20% by weight, preferably 0.1% to 20% by weight, of at least one additive;

[0046] - 0.01 to 2% by weight of a crosslinking agent, preferably a peroxide;

[0047] The total amount amounts to 100% by weight of the mixture.

[0048] According to one aspect, the present invention relates to a cross-linked foam formed on the basis of the composition as described above.

[0049] The present invention also relates to a method for preparing a foam, the method comprising:

[0050] (i) providing a mixture comprising:

[0051] - copolymer (a),

[0052] - copolymer (b),

[0053] - a cross-linking agent, preferably a peroxide,

[0054] - a blowing agent, preferably a chemical blowing agent, and

[0055] - optionally a polyolefin (c), a thermoplastic elastomeric polymer (d) and at least one additive;

[0056] (ii) shaping the mixture by injection molding, compression / molding or extrusion;

[0057] (iii) a step of foaming the mixture.

[0058] The above steps can be performed individually or simultaneously.

[0059] According to one embodiment, steps (i)+(ii), (ii)+(iii) or (i)+(ii)+(iii) are performed simultaneously.

[0060] The steps of the preparation process can be carried out in the same item of equipment, for example in a mixer or an extruder.

[0061] According to one embodiment, step (i) is carried out by mixing in the molten state:

[0062] - 30% to 99.9% by weight, typically 50% to 99.9% by weight, preferably 60% to 99.9% by weight, of copolymer (a);

[0063] - 0.1 to 50% by weight, typically 0.1 to 40% by weight, preferably 0.1 to 30% by weight, of copolymer (b);

[0064] - 0 to 50% by weight of polyolefins (c) and / or thermoplastic elastomeric polymers (d);

[0065] - 0% to 20% by weight, preferably 0.1% to 20% by weight, of at least one additive;

[0066] - 0.01 to 2% by weight of a crosslinking agent, preferably a peroxide;

[0067] - 0.5 to 10% by weight of a blowing agent, preferably a chemical blowing agent,

[0068] The total amount amounts to 100% by weight of the mixture.

[0069] According to another variant, the blowing agent is introduced during and / or after step (ii).The amount of blowing agent introduced into the process is generally between 0.5% and 10% by weight relative to the total weight of the mixture.

[0070] In this case, the mixture introduced in step (i) is a composition as defined above.

[0071] The invention also relates to a composition or foam obtainable by a process according to the above description.

[0072] The process according to the invention makes it possible to prepare polymer foams which are regular, homogeneous and have the advantageous properties mentioned above.

[0073] Thus, the present invention provides a foam as described above, which has a low density, is uniform and regular, and has one or more of the following advantageous properties: high capacity to recover elastic energy during low stress loading; low compression set (and therefore improved durability); high springback recovery; and improved recovery properties.

[0074] This is achieved by incorporating the PEBA copolymers into crosslinked foams of ethylene vinyl acetate (EVA) and / or ethylene and alkyl (meth)acrylates.

[0075] Typically, the foam obtained at the end of the preparation process described above consists essentially of, or consists of:

[0076] - (co)polymers forming the polymer matrix of the foam, and

[0077] - decomposition products and / or by-products of at least one blowing agent and at least one crosslinking agent and optionally at least one additive, which are dispersed in the polymer matrix.

[0078] The present invention relates to the use of a composition or a foam as described above for producing an article, preferably a shoe sole.

[0079] The invention also relates to an article consisting of or comprising at least one element of the composition or foam as described above.

[0080] The article may be selected from shoe soles, in particular sports shoe soles, large or small balls, gloves, personal protective equipment, track pads, motor vehicle parts, building parts and electrical and electronic equipment parts.

[0081] The present invention will now be described in more detail. DETAILED DESCRIPTION

[0082] Copolymer (a)

[0083] The copolymer (a) according to the present invention is selected from ethylene-vinyl acetate (EVA) copolymers, copolymers of ethylene and alkyl (meth)acrylates, and / or mixtures thereof.

[0084] The relative amount of vinyl acetate comonomer incorporated into the EVA copolymer may be from 0.1 wt % up to 40 wt %, or even more, of the total copolymer. For example, the EVA may have a vinyl acetate content of 2 wt % to 50 wt %, 5 wt % to 40 wt %, or 10 wt % to 30 wt %. The EVA may be modified by methods well known to those skilled in the art, including modification with unsaturated carboxylic acids or derivatives thereof such as maleic anhydride or maleic acid.

[0085] The copolymer of ethylene and (meth) alkyl acrylate comprises the repeating unit derived from ethylene and alkyl acrylate, alkyl methacrylate or its combination, wherein the alkyl fragment contains 1 to 8 carbon atoms.The example of alkyl comprises methyl, ethyl, propyl, butyl or two or more combinations in these.(Meth) alkyl acrylate comonomer can be incorporated into ethylene / (meth) alkyl acrylate copolymer with 0.1 wt % to 45 wt % or even more amount of total copolymer.Alkyl can contain 1 to about 8 carbon atoms.For example, (meth) alkyl acrylate comonomer can be present in copolymer with 5 wt % to 45 wt %, 10 wt % to 35 wt % or 10 wt % to 28 wt %.The example of ethylene-(meth) alkyl acrylate copolymer comprises ethylene / methyl acrylate, ethylene / ethyl acrylate, ethylene / butyl acrylate or two or more combinations in these.The mixture of two or more different ethylene-(meth) alkyl acrylate copolymers can be used.

[0086] The copolymer (a) may have a melt flow index (MFI) of 0.1 to 60 g / 10 min or 0.3 to 30 g / 10 min. Preferably, the copolymer (a) has a low melt flow index, such as 0.1 to 20, or 0.5 to 20, or 0.5 to 10, or 0.1 to 5 g / 10 min.

[0087] In the context of the present invention, unless otherwise stated, the melt flow index (MFI) (expressed in g / 10 min) is measured according to standard ISO 1133 at a temperature of 190° C. under a load of 2160 grams.

[0088] Copolymer (b)

[0089] The branched PEBA copolymer generally has an instantaneous hardness less than or equal to 72 Shore D, more preferably less than or equal to 68 Shore D or 55 Shore D or 45 Shore D. The hardness measurement can be carried out according to standard ISO 868:2003.

[0090] Three types of polyamide blocks can advantageously be used.

[0091] According to a first type, the polyamide blocks are derived from the condensation of dicarboxylic acids, in particular those containing 4 to 36 carbon atoms, preferably those containing 6 to 18 carbon atoms, and diamines, in particular those containing 2 to 20 carbon atoms, preferably those containing 5 to 14 carbon atoms.

[0092] As examples of dicarboxylic acids, mention may be made of 1,4-cyclohexanedicarboxylic acid, succinic acid, adipic acid, azelaic acid, suberic acid, sebacic acid, dodecanedicarboxylic acid, octadecanedicarboxylic acid, terephthalic acid and isophthalic acid, and also dimer fatty acids.

[0093] As examples of diamines, mention may be made of 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), p-aminodicyclohexylmethane (PACM), isophoronediamine (IPDA), 2,6-bis(aminomethyl)norbornane (BAMN) and piperazine (Pip).

[0094] Advantageously, the 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 derived from the diamine residue and Y represents the number of atoms derived from the diacid residue, as is conventional.

[0095] According to a second type, the polyamide blocks are produced by the condensation of one or more α,ω-aminocarboxylic acids containing 6 to 12 carbon atoms and / or one or more lactams in the presence of dicarboxylic acids or diamines containing 4 to 12 atoms. Mention may be made, as examples of lactams, of caprolactam, enantholactam and lauryl lactam. Mention may be made, as examples of α,ω-aminocarboxylic acids, of aminocaproic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid and 12-aminododecanoic acid.

[0096] Advantageously, the second type of polyamide blocks are PA 11 (polyundecamide), PA 12 (polydodecanamide) or PA 6 (polycaprolactam) blocks. In the notation PA X, X represents the number of carbon atoms derived from the amino acid residue.

[0097] According to a third type, the polyamide blocks result from the condensation of at least one α,ω-aminocarboxylic acid (or lactam), at least one diamine and at least one dicarboxylic acid.

[0098] In this case, the polyamide PA blocks are prepared by polycondensation as follows:

[0099] - linear aliphatic or aromatic diamines containing X carbon atoms;

[0100] - a dicarboxylic acid containing Y carbon atoms; and

[0101] - a comonomer {Z} selected from lactams and α,ω-aminocarboxylic acids containing Z carbon atoms, and an equimolar mixture of at least one diamine containing X1 carbon atoms and at least one dicarboxylic acid containing Y1 carbon atoms, (X1, Y1) being different from (X, Y);

[0102] said comonomer {Z} is introduced in a weight proportion advantageously ranging up to 50%, preferably up to 20%, even more advantageously up to 10%, relative to the total amount of polyamide precursor monomers;

[0103] - in the presence of a chain limiter selected from dicarboxylic acids.

[0104] Advantageously, a dicarboxylic acid containing Y carbon atoms is used as chain limiter, which is introduced in a stoichiometric excess relative to the diamine.

[0105] According to a variant of this third type, the polyamide blocks are produced by the condensation of at least two α,ω-aminocarboxylic acids containing 6 to 12 carbon atoms or at least two lactams or one lactam and one aminocarboxylic acid not having the same number of carbon atoms, optionally in the presence of a chain limiter. As examples of aliphatic α,ω-aminocarboxylic acids, mention may be made of aminocaproic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid and 12-aminododecanoic acid. As examples of lactams, mention may be made of caprolactam, enantholactam and lauryl lactam. As examples of aliphatic diamines, mention may be made of hexamethylenediamine, dodecamethylenediamine and trimethylhexamethylenediamine. As examples of alicyclic diacids, mention may be made of 1,4-cyclohexanedicarboxylic acid. As examples of aliphatic diacids, mention may be made of succinic acid, adipic acid, azelaic acid, suberic acid, sebacic acid, dodecanedicarboxylic acid and dimerized fatty acids. These dimer fatty acids preferably have a dimer content of at least 98%; they are preferably hydrogenated; they are products sold, for example, by Croda under the trade name Pripol, by BASF under the trade name Empol, or by Oleon under the trade name Radiacid, or polyoxyalkylene α,ω-diacids. As examples of aromatic diacids, terephthalic acid (T) and isophthalic acid (I) may be mentioned. As examples of alicyclic diamines, bis(4-aminocyclohexyl)methane (BACM), bis(3-methyl-4-aminocyclohexyl)methane (BMACM) and isomers of 2,2-bis(3-methyl-4-aminocyclohexyl)propane (BMACP) and para-aminodicyclohexylmethane (PACM) may be mentioned. Other commonly used diamines may be isophoronediamine (IPDA), 2,6-bis(aminomethyl)norbornane (BAMN) and piperazine.

[0106] As examples of polyamide blocks of the third type, mention may be made of the following:

[0107] - PA 6.6 / 6, where 6.6 represents the condensation of hexamethylenediamine units with adipic acid and 6 represents the units resulting from the condensation of caprolactam;

[0108] PA 6.6 / 6.10 / 11 / 12, wherein 6.6 represents the condensation of hexamethylenediamine with adipic acid, 6.10 represents the condensation of hexamethylenediamine with sebacic acid, 11 represents the units resulting from the condensation of aminoundecanoic acid, and 12 represents the units resulting from the condensation of lauryl lactam.

[0109] The notation PAX / Y, PAX / Y / Z etc. relates to copolyamides, wherein X, Y, Z etc. represent homopolyamide units as described above.

[0110] As examples of copolyamides, mention may be made of copolymers of caprolactam and lauryl lactam (PA 6 / 12), copolymers of caprolactam, adipic acid and hexamethylenediamine (PA 6 / 66), copolymers of caprolactam, lauryl lactam, adipic acid and hexamethylenediamine (PA 6 / 12 / 66), copolymers of caprolactam, lauryl lactam, 11-aminoundecanoic acid, azelaic acid and hexamethylenediamine (PA 6 / 69 / 11 / 12), copolymers of caprolactam, lauryl lactam, 11-aminoundecanoic acid, adipic acid and hexamethylenediamine (PA 6 / 66 / 11 / 12), copolymers of lauryl lactam, azelaic acid and hexamethylenediamine (PA 69 / 12), copolymers of 11-aminoundecanoic acid, terephthalic acid and decamethylenediamine (PA 11 / 10T).

[0111] Advantageously, the polyamide blocks of copolymer (b) comprise polyamide blocks selected from the group consisting of PA 6, PA11, 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 6.9, 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 10.4, PA 10.9. 10, PA 10.10, PA 10.12, PA 6 / 12, PA 11 / 12 or mixtures or copolymers thereof; and preferably comprises blocks of polyamide PA 6, PA 11, PA 12, PA 6.10, PA 10.10, PA 10.12, PA 6 / 12, PA 11 / 12 or mixtures or copolymers thereof.

[0112] The polyether blocks of the PEBA copolymers are formed by alkylene oxide (alkylene oxide) units. The polyether blocks may in particular be PEG (polyethylene glycol) blocks (i.e. blocks formed by ethylene oxide units), and / or PPG (polypropylene glycol) blocks (i.e. blocks formed by propylene oxide units), and / or PO3G (polytrimethylene glycol) blocks (i.e. blocks formed by trimethylene glycol ether units), and / or PTMG (polytetramethylene glycol) blocks (i.e. blocks formed by tetramethylene glycol units) (also known as polytetramethylene glycol). The copolymers may contain various types of polyethers in their chains, the copolyethers possibly being in block or random form.

[0113] It is also possible to use blocks obtained by oxyethylation of bisphenols, such as bisphenol A. The latter products are described in particular in document EP 613 919.

[0114] The polyether blocks can also be formed from ethoxylated primary amines. As examples of ethoxylated primary amines, the products of the following formula may be mentioned:

[0115] [Chemical formula 1]

[0116]

[0117] wherein m and n are integers between 1 and 20, and x is an integer between 8 and 18. These products are available, for example, from CECA under the trade name and from Clariant under the trade name Commercially available.

[0118] The polyether blocks may contain polyoxyalkylene blocks with NH2 chain ends, which can be obtained by cyanoacetylation of α,ω-dihydroxylated aliphatic polyoxyalkylene blocks (known as polyether diols). More specifically, the commercial products Jeffamine or Elastamine (e.g. D400, D2000, ED 2003, XTJ 542, which are commercial products from Huntsman and are also described in documents JP 2004346274, JP 2004352794 and EP 1482011).

[0119] The polyetherdiol blocks are used in unmodified form and co-polycondensed with the polyamide blocks having carboxyl terminal groups, or are aminated to be converted into polyetherdiamines and condensed with the polyamide blocks having carboxyl terminal groups.

[0120] Although the above PEBA copolymers contain at least one polyamide block and at least one polyether block (as described above), the present invention also encompasses copolymers containing three, four (or even more) different blocks selected from, for example, those described in this specification; polyester blocks, polysiloxane blocks such as polydimethylsiloxane (PDMS) blocks, polyolefin blocks, polycarbonate blocks, and mixtures thereof. For example, the copolymer according to the present invention may be a segmented block copolymer (or "triblock" copolymer) containing three different types of blocks, which results from the condensation of a plurality of the blocks described above. The triblock may, for example, be a copolymer comprising a polyamide block, a polyester block and a polyether block, or a copolymer comprising a polyamide block and two different polyether blocks (e.g., a PEG block and a PTMG block).

[0121] PEBAs are produced by the polycondensation of polyamide blocks with reactive ends and polyether blocks with reactive ends, for example, in particular the following polycondensation:

[0122] 1) a polyamide block with a diamine chain end and a polyoxyalkylene block with a dicarboxyl chain end;

[0123] 2) polyamide blocks with dicarboxyl chain ends and polyoxyalkylene blocks with diamine chain ends (obtained, for example, by cyanoethylation and hydrogenation of α,ω-dihydroxylated aliphatic polyoxyalkylene blocks (known as polyether diols));

[0124] 3) Polyamide blocks with dicarboxyl chain ends and polyether diols, in this particular case the products obtained are polyetheresteramides.

[0125] Polyamide blocks with dicarboxyl chain ends originate, for example, from the condensation of polyamide precursors in the presence of chain-limiting dicarboxylic acids.Polyamide blocks with diamine chain ends originate, for example, from the condensation of polyamide precursors in the presence of chain-limiting diamines.

[0126] PEBA copolymers that are particularly preferred in the context of the present invention are copolymers comprising the following blocks: 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 PTMG, PA 6 / 12 and PEG, PA 11 / 12 and PTMG, PA 11 / 12 and PEG.

[0127] The PEBA copolymers according to the invention are branched copolymers whose number-average functionality (Efn) is greater than 2, preferably greater than or equal to 3.

[0128] Preferably, the branching is carried out by means of a compound comprising at least three functional groups capable of reacting with the carboxylic acid chain ends of the PEBA copolymer, thus making it possible to form a branched PEBA copolymer.

[0129] According to a first variant, the branching is carried out by incorporating polyol residues into the polyamide blocks of the PEBA copolymer, said polyol being a polyol comprising at least three hydroxyl groups.

[0130] According to this variant, the branched PEBA can be prepared, for example, by adding during its synthesis one or more polyols comprising at least three hydroxyl groups.

[0131] Branched PEBAs can be prepared according to a two-step preparation process (comprising a first step, the synthesis of the polyamide blocks, followed by a second step, the condensation of the polyamide and polyether blocks) or by a one-step preparation process. The polyol is added together with the precursor of the polyamide blocks.

[0132] The general process for preparing PEBA copolymers with ester bonds between PA blocks and PE blocks in two steps is known and described, for example, in document FR 2846332. The general process for preparing PEBA copolymers with amide bonds between PA blocks and PE blocks is known and described, for example, in document EP 1482011. The polyether blocks can also be mixed with polyamide precursors and diacid chain limiters to prepare polymers containing polyamide blocks and polyether blocks with randomly distributed units (one-step process). Regardless of the process used (two-step or one-step), the polyol is added together with the polyamide precursor.

[0133] Preferably, the branched PEBA of the invention is prepared according to a two-step preparation process.

[0134] The addition of polyols having a functionality greater than 2 creates bridges that link the polyamide blocks of the copolymer together, preferably through ester bonds.

[0135] Polyols containing at least three hydroxyl groups are understood to mean in particular:

[0136] - monomeric polyols, in particular monomeric aliphatic triols, such as glycerol, trimethylolpropane, pentaerythritol, and / or

[0137] - polymeric polyols, in particular triols containing polyether chains, polycaprolactone triols, mixed polyether-polyester polyols containing at least three hydroxyl groups.

[0138] Advantageously, the polyol is chosen from: pentaerythritol, trimethylolpropane, trimethylolethane, hexanetriol, diglycerol, methyl glucoside, tetraethanol, sorbitol, dipentaerythritol, cyclodextrin, polyether polyols comprising at least three hydroxyl groups, and mixtures thereof.

[0139] The weight average molar mass 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.

[0140] Advantageously, the polyol is added in an amount of 0.01 to 10% by weight, preferably 0.01 to 5% by weight, more preferably 0.05 to 0.5% by weight, relative to the total weight of the polyol, the precursors of the polyamide blocks and the polyether blocks. Advantageously, the polyol is added in an amount of 3.5 to 35 μeq / g, relative to the total weight of the precursors of the polyol, the polyamide blocks and the polyether blocks.

[0141] According to a second variant, the branching of copolymer (b) is carried out by incorporating residues of polyepoxide compounds, that is, polyepoxide compounds comprising at least three epoxide functions, into the polyamide blocks of said copolymer (b).

[0142] According to this variant, the branched PEBA can be prepared according to a production process comprising the steps of mixing in the molten state:

[0143] PEBA copolymers and epoxide compounds.

[0144] The epoxide equivalent weight (EEW) of the polyepoxide compounds is generally from 80 to 2800 g / mol, preferably from 90 to 700 g / mol.

[0145] According to one embodiment, the epoxide compound is selected from triglycidyl isocyanurate, trimethylolpropane triglycidyl ether, epoxy novolac resins and epoxidized oils.

[0146] According to one embodiment, the epoxide compound is chosen from random copolymers of epoxy-functional (meth)acrylates obtained by copolymerization of at least one epoxy-functional (meth)acrylic monomer and at least one monomer chosen from olefin monomers, vinyl acetate monomers, non-functional (meth)acrylic monomers, styrene monomers, or mixtures of one or more of these entities.

[0147] For the purposes of the present invention, the term (meth)acrylic monomer includes both acrylic monomers and methacrylic monomers. Examples of epoxy-functional (meth)acrylic monomers include both acrylates and methacrylates. Examples of these epoxy-functional (meth)acrylic monomers include, but are not limited to, monomers containing 1,2-epoxy groups, such as glycidyl acrylate and glycidyl methacrylate. Other suitable monomers may be allyl glycidyl ether, glycidyl ethacrylate, and glycidyl itaconate.

[0148] Suitable olefin monomers may be, but are not limited to, ethylene, propylene, butene, and mixtures of these entities.

[0149] Suitable acrylate and methacrylate monomers may be, but are not limited to, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, n-pentyl acrylate, isopentyl acrylate, isobornyl acrylate, n-hexyl acrylate, 2-ethylbutyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, n-decyl acrylate, methylcyclohexyl acrylate, cyclopentyl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, isopentyl methacrylate, sec-butyl methacrylate, isopentyl methacrylate, butyl methacrylate, 2-ethylbutyl methacrylate, methylcyclohexyl methacrylate, cinnamyl methacrylate, crotonyl methacrylate, cyclohexyl methacrylate, cyclopentyl methacrylate, 2-ethoxyethyl methacrylate, and isobornyl methacrylate.

[0150] Styrene monomers include, but are not limited to, styrene, α-methylstyrene, vinyltoluene, p-methylstyrene, tert-butylstyrene, o-chlorostyrene, vinylpyridine, and mixtures of these entities. In certain embodiments, the styrene monomers used in the present invention are styrene and α-methylstyrene.

[0151] According to one embodiment, the epoxide compound is chosen from random styrene-(meth)acrylate copolymers with epoxy functionality, obtained from monomers of at least one (meth)acrylic monomer with epoxy functionality and at least one non-functional (meth)acrylic and / or styrene monomer.

[0152] In one embodiment, the epoxide compound contains 25 to 50 wt % of at least one epoxy-functional (meth)acrylic monomer and 75 to 50 wt % of at least one non-functional (meth)acrylic and / or styrenic monomer.

[0153] More preferably, the epoxide compound contains between 25% and 50% by weight of at least one epoxy-functional (meth)acrylic monomer, between 15% and 30% by weight of at least one styrene monomer, and between 20% and 60% by weight of at least one non-functional acrylic and / or methacrylic monomer.

[0154] In one embodiment, the epoxide compound contains between 50 wt % and 80 wt % of at least one epoxy-functional (meth)acrylic monomer and 20 wt % to 50 wt % of at least one non-functional (meth)acrylic and / or styrene monomer, based on the total weight of the monomers.

[0155] More preferably, the epoxide compound contains between 50% and 80% by weight of at least one epoxy-functional (meth)acrylic monomer, between 15% and 45% by weight of at least one styrene monomer, and between 0% and 5% by weight of at least one non-functional acrylate and / or methacrylate monomer.

[0156] In one embodiment, the epoxide compound contains between 5% and 25% by weight of at least one epoxy-functional (meth)acrylic monomer and 75% to 95% by weight of at least one non-functional (meth)acrylic and / or styrene monomer. More preferably, the epoxide compound contains between 5% and 25% by weight of at least one epoxy-functional (meth)acrylic monomer, between 50% and 95% by weight of at least one styrene monomer, and between 0% and 25% by weight of at least one non-functional acrylate and / or methacrylate monomer.

[0157] According to an embodiment, the epoxide compound is chosen from epoxy-functional styrene-(meth)acrylate copolymers (obtained from monomers of at least one epoxy-functional (meth)acrylic monomer and at least one non-functional (meth)acrylic and / or styrene monomer), preferably from epoxy-functional styrene-(meth)acrylate copolymers (obtained from monomers of at least one epoxy-functional (meth)acrylic monomer and at least one styrene monomer).

[0158] According to one embodiment, the epoxide compound is obtained from at least one epoxy-functional (meth)acrylic monomer and at least one styrene monomer. According to one embodiment, the epoxide compound contains 50% to 80% by weight of at least one epoxy-functional (meth)acrylic monomer and between 20% and 50% by weight of at least one styrene monomer, relative to the total weight of the monomers.

[0159] According to a preferred embodiment, the epoxide compound is a random copolymer of styrene and glycidyl methacrylate.

[0160] The weight average molar mass (Mw) of the epoxy-functional styrene-(meth)acrylate copolymer is preferably less than 25,000 g / mol, more preferably less than 20,000 g / mol; and is generally in the range of 3,000 to 15,000 g / mol, preferably 5,000 to 10,000 g / mol.

[0161] According to one embodiment, the amount of polyepoxide compound used in the process is from 0.01% to 5% by weight, preferably from 0.01% to 2% by weight and more preferably from 0.05% to 1% by weight, relative to the total weight of the PEBA copolymer.

[0162] According to a preferred embodiment, the amount of polyepoxide compound used in the process is less than 1% by weight, generally from 0.15% to 0.95% by weight, preferably from 0.3% to 0.9% by weight, or from 0.35% to 0.85% by weight, relative to the total weight of the PEBA copolymer.

[0163] According to one embodiment, the molar ratio of the carboxylic acid chain ends content of the PEBA copolymer to the epoxide functional content of the polyepoxide compound is generally between 2 and 20, preferably between 3 and 10.

[0164] Advantageously, the process is carried out by reactive extrusion, typically in an extruder.

[0165] In the context of the present invention, the branched PEBA copolymer has a weight average molar mass Mw greater than 80 000 g / mol. Preferably, the weight average molar mass of the branched PEBA copolymer ranges from 80 000 to 300 000 g / mol, more preferably from 90 000 to 250 000 g / mol, even more preferably from 100 000 to 200 000 g / mol.

[0166] The weight-average molar mass is expressed as PMMA equivalent (used as calibration standard) and can be measured by size exclusion chromatography according to standard ISO 16014-1:2012: the copolymer is dissolved in hexafluoroisopropanol and stabilized for 24 hours at ambient temperature with 0.05 M potassium trifluoroacetate at a concentration of 1 g / l to 2 g / l before passing through the column, for example at a flow rate of 1 ml / min, the molar mass being measured by differential refractometry. Size exclusion chromatography can be carried out using a modified silica column, for example on a set of two columns comprising the following and a modified silica precolumn (for example a PGF column and precolumn from Polymer Standards Service), for example at a temperature of 40°C: a 1000 x 1000 column having a size of 300 x 8 mm and a particle size of 7 μm. Column, size 300x8mm and particle size 7μm column, and a pre-column measuring 50 x 8 mm.

[0167] In certain embodiments, the branched PEBA copolymer has a weight average molar mass Mw in the range of 80,000 to 90,000 g / mol, or 90,000 to 100,000 g / mol, or 10,000 to 125,000 g / mol, or 125,000 to 150,000 g / mol, or 15,000 to 175,000 g / mmol, or 175,000 to 200,000 g / mol, or 200,000 to 225,000 g / mol, or 225,000 to 250,000 g / mol, or 250,000 to 275,000 g / mol, or 275,000 to 300,000 g / mol.

[0168] The branched PEBA copolymers may have a number average molar mass Mn ranging from 30 000 to 100 000 g / mol, preferably from 35 000 to 80 000 g / mol, more preferably from 40 000 to 70 000 g / mol.

[0169] The number average molar mass is expressed as PMMA equivalent and can be measured according to standard ISO 16014-1 according to the method described above. In certain embodiments, the branched copolymer containing rigid blocks and soft blocks has a number average molar mass Mn in the range of 30 000 to 35 000 g / mol, or 35 000 to 40 000 g / mol, or 40 000 to 45 000 g / mol, or 45 000 to 50 000 g / mol, or 50 000 to 55 000 g / mol, or 55 000 to 60 000 g / mol, or 60 000 to 70 000 g / mol, or 70 000 to 80 000 g / mol, or 80 000 to 90 000 g / mol, or 90 000 to 100 000 g / mol.

[0170] The branched PEBA copolymer may have a z-average molar mass Mz ranging from 200 000 to 1 000 000 g / mol. The z-average molar mass Mz is expressed as PMMA equivalent and may be measured according to standard ISO 16014-1 according to the method described above. In certain embodiments, the branched copolymer containing the rigid block and the flexible block has a molecular weight in the range of 200,000 to 250,000 g / mol, or 250,000 to 300,000 g / mol, or 300,000 to 350,000 g / mol, or 350,000 to 400,000 g / mol, or 400,000 to 450,000 g / mol, or 450,000 to 500,000 g / mol, 500,000 to 550,000 g / mol, 550,000 to 600,000 g / mol, 600,000 to 650,000 g / mol, 650,000 to 700,000 g / mol, 700,000 to 750,000 g / mol, 750,000 to 800,000 g / mol, The polydispersity of the copolymers can be defined by the ratio of the weight-average molar mass Mw of the copolymer to the number-average molar mass Mn of the copolymer (Mw / Mn molar mass ratio) and / or by the ratio of the z-average molar mass Mz of the copolymer to the weight-average molar mass Mn of the copolymer (Mz / Mw molar mass ratio).

[0171] The branched PEBA copolymer has a Mw / Mn molar mass ratio greater than or equal to 2.2, preferably greater than or equal to 2.4. In certain embodiments, the copolymer has a Mw / Mn molar mass ratio greater than or equal to 2.3, or greater than or equal to 2.4, or greater than or equal to 2.5, or greater than or equal to 2.6, or greater than or equal to 2.7, or greater than or equal to 2.8, or greater than or equal to 2.9, or greater than or equal to 3.

[0172] The branched PEBA copolymer may have a molar mass ratio Mz / Mw greater than or equal to 1.8, preferably greater than or equal to 2.0, preferably greater than or equal to 2.5, or greater than or equal to 2.7, or greater than or equal to 2.9, or greater than or equal to 3.1, or greater than or equal to 3.3, or greater than or equal to 3.5.

[0173] Polyolefin (c)

[0174] The composition may comprise a polyolefin (c) selected from functionalized polyolefins (c1) and non-functionalized polyolefins (c2) and mixtures thereof.

[0175] The polyolefin may generally have a flexural modulus of less than 100 MPa (measured according to Standard ISO 178) and a Tg of less than 0° C. (measured at the inflection point of the DSC thermogram according to Standard 11357-2).

[0176] The non-functionalized polyolefin (c2) is generally a homopolymer or copolymer of an α-olefin or a diene, such as ethylene, propylene, 1-butene, 1-octene or butadiene. By way of example, mention may be made of:

[0177] - polyethylene homopolymers and copolymers, in particular LDPE, HDPE, LLDPE (linear low-density polyethylene), VLDPE (very low-density polyethylene) and metallocene polyethylene,

[0178] - propylene homopolymer or copolymer,

[0179] - Ethylene / α-olefin copolymers, such as ethylene / propylene, EPR (abbreviation for ethylene propylene rubber) and ethylene / propylene / diene (EPDM).

[0180] The functionalized polyolefin (c1) may be a polymer of an α-olefin with a reactive unit; such a reactive unit is an acid, anhydride or epoxide function. By way of example, the aforementioned polyolefin (C2) may be mentioned, which is grafted with or copolymerized or terpolymerized with an unsaturated epoxide, for example glycidyl (meth)acrylate; or a carboxylic acid or a corresponding salt or ester, for example (meth)acrylic acid (the latter may be completely or partially neutralized by a metal such as Zn, etc.); or a carboxylic anhydride such as maleic anhydride. The functionalized polyolefin is, for example, a PE / EPR mixture, the weight ratio of which may vary within wide limits, for example between 40 / 60 and 90 / 10, the mixture being co-grafted with an anhydride, in particular maleic anhydride, according to the degree of grafting, for example from 0.01% to 5% by weight.

[0181] The functionalized polyolefin (c1) can be selected from the following (co)polymers grafted with maleic anhydride or glycidyl methacrylate, wherein the degree of grafting is, for example, 0.01% to 5% by weight:

[0182] PE, PP, copolymers of ethylene with propylene, butene, hexene or octene, said copolymers containing, for example, 35 to 80% by weight of ethylene;

[0183] - ethylene / α-olefin copolymers, such as ethylene / propylene, EPR (abbreviation for ethylene propylene rubber) and ethylene / propylene / diene (EPDM);

[0184] - copolymers of ethylene and vinyl acetate (EVA), containing up to 40% by weight of vinyl acetate;

[0185] - copolymers of ethylene and alkyl (meth)acrylates containing up to 40% by weight of alkyl (meth)acrylates;

[0186] - Copolymers of ethylene and vinyl acetate (EVA) and alkyl (meth)acrylates containing up to 40% by weight of comonomers.

[0187] The functionalized polyolefin (c1) can also be chosen from ethylene / propylene copolymers, mainly propylene, grafted with maleic anhydride and then condensed with a monoaminated polyamide (or polyamide oligomer) (products described in EP-A-0 342 066).

[0188] The functionalized polyolefin (c1) may also be a copolymer or terpolymer of at least the following units: (1) ethylene, (2) an alkyl (meth)acrylate or a saturated vinyl carboxylate, and (3) an anhydride such as maleic anhydride or (meth)acrylic anhydride, or an epoxide such as glycidyl (meth)acrylate.

[0189] As examples of functionalized polyolefins of the latter type, mention may be made of the following copolymers, in which ethylene preferably represents at least 60% by weight of the copolymer, and in which the termonomer (functional group) represents, for example, 0.1% to 10% by weight of the copolymer:

[0190] - ethylene / alkyl (meth)acrylate / (meth)acrylic acid or maleic anhydride or glycidyl methacrylate copolymers;

[0191] - ethylene / vinyl acetate / maleic anhydride or glycidyl methacrylate copolymers;

[0192] - Ethylene / vinyl acetate or alkyl (meth)acrylate / (meth)acrylic acid or maleic anhydride or glycidyl methacrylate copolymers.

[0193] In the aforementioned copolymer, the (meth)acrylic acid may form a salt with Zn or Li.

[0194] The term "alkyl (meth)acrylate" in (c1) or (c2) means C1 to C8 alkyl methacrylate and C1 to C8 alkyl acrylate, and may be selected from: methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, methyl methacrylate and ethyl methacrylate.

[0195] The above copolymers (c1) and (c2) may be copolymerized randomly or in blocks, and may have a linear or branched structure.

[0196] The non-functionalized polyolefin (c2) is advantageously chosen from polypropylene homopolymers or copolymers, and any ethylene homopolymers, or copolymers of ethylene and higher α-olefin type comonomers (such as butene, hexene, octene or 4-methyl-1-pentene). For example, PP, high-density PE, medium-density PE, linear low-density PE, low-density PE or ultra-low-density PE may be mentioned. As known to those skilled in the art, these polyethylenes are produced according to a "free radical" process, according to a "Ziegler" type catalysis or more recently according to a "metallocene" catalysis.

[0197] The functionalized polyolefin (c1) is advantageously chosen from any polymer comprising α-olefin units and units carrying reactive polar functions, such as epoxide, carboxylic acid or carboxylic anhydride functions. By way of example of such polymers, mention may be made of terpolymers of ethylene, alkyl acrylates and maleic anhydride or glycidyl methacrylate, such as products; or polyolefins grafted with maleic anhydride, such as products; and terpolymers of ethylene, alkyl acrylates and (meth)acrylic acid. Mention may also be made of homopolymers or copolymers of polypropylene grafted with carboxylic anhydrides and then condensed with polyamides or monoaminated oligomers of polyamides.

[0198] It has been observed that functionalized polyolefin (c1) can improve the compatibility between copolymer (a) and copolymer (b).

[0199] According to one embodiment, the composition comprises 0.1% to 50% by weight, preferably 0.1% to 40% by weight; or 0.1% to 30% by weight, or 0.1% to 20% by weight of a polyolefin (c) as described above, relative to the total weight of the composition.

[0200] Thermoplastic elastomer polymer (d)

[0201] According to one embodiment, the composition comprises from 0.1% to 50% by weight, preferably from 0.1% to 40% by weight; or from 0.1% to 30% by weight, or from 0.1% to 20% by weight of a thermoplastic elastomeric polymer (d), relative to the total weight of the composition, the thermoplastic elastomeric polymer (d) being chosen from copolymers containing polyester blocks and polyether blocks, linear PEBAs, polyurethanes, olefinic thermoplastic elastomers or olefinic block copolymers, styrene-diene block copolymers and / or mixtures thereof.

[0202] The copolymer containing polyester blocks and polyether blocks is generally composed of a flexible polyether block derived from a polyether diol and a rigid polyester block produced by the reaction of at least one dicarboxylic acid with at least one chain-extending short diol unit. The polyester block and the polyether block are connected via ester bonds produced by the reaction of the acid function of the dicarboxylic acid with the hydroxyl function of the polyether diol. The sequence of polyether and diacid forms a flexible block, while the sequence of ethylene glycol or butanediol and diacid forms a rigid block of the copolyetherester. The chain-extending short diol can be selected from neopentyl glycol, cyclohexanedimethanol and aliphatic diols of the formula HO(CH2)nOH, where n is an integer ranging from 2 to 10.

[0203] Advantageously, the diacid is an aromatic dicarboxylic acid containing 8 to 14 carbon atoms. Up to 50 mol % of the aromatic dicarboxylic acid can be replaced by at least one other aromatic dicarboxylic acid containing 8 to 14 carbon atoms and / or up to 20 mol % can be replaced by an aliphatic dicarboxylic acid containing 2 to 14 atoms.

[0204] As examples of aromatic dicarboxylic acids, mention may be made of terephthalic acid, isophthalic acid, dibenzoic acid, naphthalene dicarboxylic acid, 4,4′-diphenylenedicarboxylic acid, bis(p-carboxyphenyl)methane acid, ethylenebis(p-benzoic acid), 1,4-tetramethylenebis(p-oxybenzoic acid), ethylenebis(p-oxybenzoic acid) and 1,3-trimethylenebis(p-oxybenzoic acid).

[0205] As examples of diols, mention may be made of ethylene glycol, 1,3-trimethylene glycol, 1,4-tetramethylene glycol, 1,6-hexamethylene glycol, 1,3-propylene glycol, 1,8-octamethylene glycol, 1,10-decamethylene glycol and 1,4-cyclohexylenedimethanol. Copolymers containing polyester blocks and polyether blocks are, for example, copolymers containing polyether units derived from polyether diols such as polyethylene glycol (PEG), polypropylene glycol (PPG), polytrimethylene glycol (PO3G) or polytetramethylene glycol (PTMG), dicarboxylic acid units such as terephthalic acid, and diol (ethylene glycol) or 1,4-butanediol units. Such copolyetheresters are described in patents EP 402 883 and EP 405 227. These polyethers are thermoplastic elastomers. They may contain plasticizers.

[0206] The composition may contain a linear PEBA. The number average molar mass Mn of the polyamide block in the linear copolymer is preferably from 400 to 13 000 g / mol, more preferably from 500 to 10 000 g / mol and even more preferably from 600 to 9000 g / mol or between 600 and 6000 g / mol. The number average molar mass of the polyether block is preferably from 100 to 3000 g / mol, preferably from 200 to 2000 g / mol.

[0207] The number-average molar mass is set by the content of chain limiters. It can be calculated according to the following relationship:

[0208] M n =n 单体 x MW 重复单元 / n 限链剂 +MW 限链剂

[0209] In this formula, n 单体 represents the number of moles of monomer, n 限链剂 Represents the number of moles of excess chain limiter, MW 重复单元 represents the molar mass of the repeating unit, and MW 限链剂 Represents the molar mass of excess chain limiter.

[0210] The number-average molar masses of the polyamide blocks and polyether blocks can be measured before the copolymerization of the blocks by gel permeation chromatography (GPC) according to standard 16014-1:2012 in tetrahydrofuran (THF).

[0211] Advantageously, the mass ratio of polyamide blocks relative to polyether blocks of the copolymer is from 0.1 to 20, preferably from 0.3 to 5, even more preferably from 0.3 to 2.

[0212] Thermoplastic polyurethanes are linear or slightly branched polymers consisting of rigid blocks and flexible elastic blocks. They can be prepared by reacting flexible elastomeric polyethers or polyesters with hydroxyl end groups with diisocyanates such as methylene diisocyanate or toluene diisocyanate. These polymers can be chain extended with diols, diamines, diacids or amino alcohols. The reaction product of isocyanates and alcohols is a polyurethane, and these blocks are relatively hard and have a high melting point. These hard blocks with a high melting point are the reason for the thermoplastic nature of polyurethanes.

[0213] Olefinic thermoplastic elastomers comprise repeating units of ethylene and a higher primary olefin, such as propylene, hexene, octene, or a combination of two or more of these, and optionally 1,4-hexadiene, ethylidene norbornene, norbornadiene, or a combination of two or more of these. The olefinic elastomer may be functionalized by grafting with anhydrides such as maleic anhydride.

[0214] Styrene-diene block copolymers comprise repeating units derived from polystyrene units and polydiene units. The polydiene units are derived from polybutadiene, polyisoprene units or copolymers of the two. The copolymers may be hydrogenated to produce saturated rubber backbone segments commonly referred to as styrene / butadiene / styrene (SBS) or styrene / isoprene / styrene (SIS) thermoplastic elastomers or styrene / ethylene-butylene / styrene (SEBS) or styrene / ethylene-propylene / styrene (SEPS) block copolymers. They may also be functionalized by grafting with anhydrides such as maleic anhydride.

[0215] Crosslinking agent

[0216] The composition comprises 0.01 wt % to 2 wt %, preferably 0.05 wt % to 2 wt %, or 0.05 wt % to 1.8 wt % of a crosslinking agent, relative to the weight of the total composition. Generally speaking, the crosslinking agent is selected from agents capable of crosslinking EVA, which may comprise one or more organic peroxides, for example selected from dialkyl peroxides, peroxyesters, peroxydicarbonates (salts), peroxyketals, diacyl peracids, or a combination of two or more of these. Examples of peroxides include dicumyl peroxide, di(3,3,5-trimethylhexanoyl)peroxide, tert-butyl peroxypivalate, tert-butyl peroxyneodecanoate, di(sec-butyl)peroxydicarbonate, tert-amyl peroxyneodecanoate, 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, tert-butyl-cumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 1,3-bis(tert-butylperoxyisopropyl)benzene, or a combination of two or more of these. These and other peroxides may be marketed under the trade names (sold by Arkema).

[0217] Foaming agent

[0218] The composition may comprise 0.5% to 10% by weight, preferably 0.5% to 8% by weight, of a blowing agent, relative to the total weight of the composition. The blowing agent (also called foaming agent) may be a chemical or physical agent. It is preferably a chemical agent, such as azodicarbonamide, dinitrosopentamethylenetetramine, p-toluenesulfonylhydrazide, p,p'-oxybis(benzenesulfonylhydrazide), or a combination of two or more of these, or a mixture based on citric acid and sodium bicarbonate (NaHCO3), such as styrene from Clariant. Series of products). It can also be a physical agent, such as dinitrogen or carbon dioxide, or a hydrocarbon, chlorofluorocarbon, hydrochlorocarbon, hydrofluorocarbon or hydrochlorofluorocarbon (saturated or unsaturated). For example, butane or pentane can be used. To adapt to the expansion decomposition temperature and foaming process, the blowing agent can be a (physical and / or chemical) blowing agent, or a mixture of a blowing agent and an activator.

[0219] According to one embodiment, when a chemical blowing agent is used, the foam additionally comprises 0.1 wt % to 10 wt %, or preferably 0.1 wt % to 5 wt % of an activator of the blowing agent. The activator may be one or more metal oxides, metal salts or organometallic complexes, or a combination of two or more of these. Examples include ZnO, zinc stearate, MgO, or a combination of two or more thereof.

[0220] additive

[0221] The composition may comprise 0.1 to 20 wt %, preferably 0.1 to 15 wt %, or 0.1 to 12 wt %, or 0.1 to 10 wt % of additives relative to the total weight of the composition.

[0222] The additives are generally conventional additives used in foams which contribute to improving the properties of the foam and / or the foaming process.

[0223] Typically, the additions may be pigments (TiO2 and other compatible colored pigments), dyes, adhesion promoters (for improving the adhesion of the expanded foam to other materials), organic or inorganic fillers (e.g., calcium carbonate, barium sulfate and / or silicon oxide), reinforcing agents, plasticizers, nucleating agents (in pure form or in concentrated form, such as CaCO3, ZnO, SiO2 or a combination of two or more of these), rubbers (for improving rubber elasticity, such as natural rubber, SBR, polybutadiene and / or ethylene propylene terpolymers), stabilizers, antioxidants, UV absorbers, flame retardants, carbon black, carbon nanotubes, mold release agents, impact agents, and additives for improving processability (processing aids), such as stearic acid). Antioxidants (to modify sensory properties, such as reducing odor or taste) may include phenolic antioxidants, such as IRGANOX from Ciba Geigy Inc. (Tarrytown, NY).

[0224] method

[0225] The foam of the invention can be obtained from the composition as defined above by a number of processes, such as compression moulding, injection moulding or a mixture of extrusion and moulding.

[0226] The present invention also relates to a method for preparing a foam, the method comprising:

[0227] (i) providing a mixture comprising:

[0228] - copolymer (a),

[0229] - copolymer (b),

[0230] - a cross-linking agent, preferably a peroxide,

[0231] - a blowing agent, preferably a chemical blowing agent, and

[0232] - optionally a polyolefin (c), a thermoplastic elastomeric polymer (d) and at least one additive;

[0233] (ii) shaping the mixture by injection molding, compression / molding or extrusion;

[0234] (iii) a step of foaming the mixture.

[0235] The above steps can be performed individually or simultaneously.

[0236] According to one embodiment, steps (i)+(ii), (ii)+(iii) or (i)+(ii)+(iii) are performed simultaneously.

[0237] The steps of the preparation process can be carried out in the same item of equipment, for example in a mixer or an extruder.

[0238] According to one embodiment, step (i) is carried out by mixing in the molten state as follows:

[0239] - 30% to 99.9% by weight of copolymer (a);

[0240] - 0.1 to 50% by weight, typically 0.1 to 40% by weight, of a PEBA copolymer (b);

[0241] - 0 to 50% by weight of polyolefins (c) and / or thermoplastic elastomeric polymers (d);

[0242] - 0.1 to 20% by weight of at least one additive;

[0243] - 0.01 to 2% by weight of a crosslinking agent, preferably a peroxide;

[0244] - 0.5 to 10% by weight of a blowing agent, preferably a chemical blowing agent,

[0245] The total amount amounts to 100% by weight of the mixture.

[0246] According to another variant, the blowing agent is introduced during and / or after step (ii).The amount of blowing agent introduced into the process is generally between 0.5% and 10% by weight relative to the total weight of the mixture.

[0247] At the end of the mixing step a homogeneous molten mixture is obtained.

[0248] The compounds can be mixed by any means known to those skilled in the art, for example using a Banbury mixer, an intensive mixer, a roll mixer, an open mill or an extruder.

[0249] Time, temperature and shear rate can be adjusted to ensure optimal dispersion without premature crosslinking or foaming. High mixing temperatures can lead to premature crosslinking and foaming due to the decomposition of crosslinking agents (e.g., peroxides) and blowing agents. When these compounds are mixed at a temperature of about 60°C to about 200°C, or 80°C to 180°C, or 70°C to 150°C, or 80°C to 130°C, they can form a homogeneous mixture. For satisfactory operation, the upper temperature limit can depend on the initial decomposition temperature of the crosslinking agent and blowing agent used.

[0250] The (co)polymers may be mixed in the molten state before being mixed with the other compounds. For example, the polymers may be mixed in the molten state in an extruder at a temperature ranging up to about 250° C. to achieve good latent mixing. The resulting mixture may then be mixed with the other compounds described above.

[0251] After mixing, shaping can be performed by injection molding, compression in a mold or extrusion.

[0252] The mixture can be shaped into the form of sheets, pellets or granules with appropriate size for foaming. Roll mixers are often used to produce sheets. Extruders can be used to shape the composition into the form of pellets or granules.

[0253] The foaming step can be carried out in a compression mold at a temperature and time that allows the decomposition of the crosslinking agent and the foaming agent to be achieved. The foaming step can be carried out during the injection of the composition into the mold and / or by opening the mold. Those skilled in the art can easily adjust the temperature and time applied during the foaming step to optimize the foaming of the copolymer of EVA and / or ethylene and (meth) alkyl acrylate. Alternatively, the foaming step can be directly carried out when exiting extrusion. The resulting foam can also be further shaped into the size of the finished product by any means known in the art, for example, by thermoforming and compression molding.

[0254] It has been observed that the PEBA copolymer does not contribute to the crosslinking of the foam under these conditions, but surprisingly its presence does not hinder the formation of crosslinked foams of EVA and / or copolymers of ethylene and alkyl (meth)acrylate and further provides particularly interesting properties to the foam as described above.

[0255] Foam and its uses

[0256] The foam according to the invention preferably has a mass fraction of less than or equal to 800 kg / m 3 , more preferably less than or equal to 600kg / m 3 , even more preferably less than or equal to 400 kg / m 3 or 300kg / m 3 , and particularly preferably less than or equal to 200 kg / m 3 For example, it may have a density of 25 to 800 kg / m 3 , and more particularly preferably 50 to 600 kg / m 3 , or 50 to 200 kg / m 3 The density can be controlled by adjusting the parameters of the production process.

[0257] Preferably, the foam has a rebound recovery greater than or equal to 50%, preferably greater than or equal to 55%, according to standard ISO 8307:2007. Generally, the elasticity of the foam of the invention is less than 80%, or 75%, or 70%.

[0258] Preferably, the foam has a compression set after 30 minutes, according to standard ISO 7214:2012, less than or equal to 60%, and preferably less than or equal to 55%, or less than or equal to 50%.

[0259] Preferably, the foam also has excellent properties in terms of fatigue strength and damping.

[0260] The foam of the present invention has improved recovery while still maintaining appropriate stiffness and lightness, good dimensional stability and good abrasion resistance, which is particularly suitable for application in shoes.

[0261] The foam of the present invention provides better adhesion to other elements to facilitate complex assembly. This is because EVA foam is a substrate that is not very polar and has a weak adhesion to other elements of the shoe, thereby complicating the assembly steps. This is particularly significant in the context of shoes (which are often in multi-layer form).

[0262] The foam according to the invention can be used to produce sports articles, such as sports shoe soles, ski boots, midsoles, insoles, or functional sole parts, in the form of inserts in parts of the sole, such as the heel or the arch, or shoe upper parts, in the form of reinforcements or inserts in shoe upper structures, or in the form of protection.

[0263] It can also be used to prepare balls, sports gloves (e.g. football gloves), golf ball parts, rackets, protective elements (jackets, inner parts of helmets, shells, etc.).

[0264] Typically, these articles can be produced by injection molding, or by injection molding followed by compression.

[0265] The foam according to the invention has advantageous anti-impact, anti-vibration and anti-noise properties, combined with tactile properties suitable for use in equipment goods. It can therefore also be used to produce rail pads, or various components in the automotive industry, transport, electrical and electronic equipment, construction or manufacturing industries.

[0266] Example

[0267] The examples were carried out with the mixtures described in Table 1.

[0268] The EVA copolymer used is a product sold by SK Functional Polymer 28-05, an EVA copolymer having a vinyl acetate content of 28 wt% and a melt flow index of 5 g / 10 minutes.

[0269] The branched copolymers of Example 1 and Comparative Example 2 comprise PA 6 / 12 blocks having a number average molar mass of 1000 g / mol and PTMG blocks having a number average molar weight of 1000 g / mmol. According to the scheme described in document EP1783156A1, branching is carried out by adding a polyol residue of the trimethylolpropane type containing three hydroxyl groups in an amount of 0.01% by weight relative to the total weight of the PEBA copolymer. The copolymer branched in this way has a weight average molar mass Mw of 134 000 g / mol, a Mw / Mn molar mass ratio of 2.9, and a Mz / Mw molar mass ratio of 2.2. The compound is mixed in a mixer at 100 ° C for 10 minutes to form a melt. The mixture is then shaped (in the form of a sheet) at 95 ° C using a roll mixer. The obtained sheet is then foamed by compression / molding at 160 ° C for 20 minutes in a press (Darragon).

[0270] The mechanical tests performed on the foams were as follows:

[0271] -Density measurement (kg / m 3), according to standard ISO 845;

[0272] -Hardness (Asker C),

[0273] - Shrinkage after 1 hour at 70°C (%),

[0274] - Ball rebound recovery (%): according to standard ISO 8307 (a steel ball of 16.8 g and 16 mm diameter is dropped from a height of 500 mm onto the foam sample; the rebound recovery then corresponds to the percentage of energy returned to the ball, or to the percentage of the initial height reached by the ball on rebound), and

[0275] - Compression set (comp.set %): a measurement consisting in compressing the sample to a given deformation for a given time, then releasing the stress and recording the residual deformation after the recovery time; said measurement is adapted from standard ISO 7214 with 50% deformation, 6 hours holding time and 50°C temperature.

[0276] [Table 1]

[0277]

[0278] PHR = parts per hundred resin (a unit of measurement used in formulations to represent the parts of an ingredient by mass per hundred polymer matrix).

[0279] The parameter "foamability" appearing in Table 1 represents the ability of a composition to repeatedly form quality foam. It is determined according to the following criteria:

[0280] o: The foam expands well in three spatial directions, the size of the foam is maintained after cooling, and the cell structure is fine and uniform.

[0281] x: weak expansion of the foam (or none at all), loss of foam size due to collapse upon cooling, and / or a rough and non-uniform cell structure.

[0282] [Table 2]

[0283] Comparative Example 1 Example 1 Rebound recovery ％ 50 54 density <![CDATA[kg / m 3 ]]> 210 181 hardness Asker C 44 41 Compression set % (50%, 6 hours) 55 54 shrink %(70℃, 1 hour) 5 2.3

[0284] A crosslinked EVA foam containing 20 wt.% of branched PEBA in the polymer matrix (Example 1) was formed homogeneously and stably. The results of the test were reproducible (3 foams were produced in 3 tests). Evaluation of the mechanical properties of the foam revealed an increase in resilience by 50% vs. 54%, a decrease in density (210 vs. 181 kg / m 3 ), no degradation in hardness or compression set, and reduced shrinkage after annealing at 70° C. for 1 hour. Comparative Example 2 shows that it is not possible to obtain quality foam from branched PEBA alone under similar conditions.

Claims

1. A composition comprising: - 30% to 99.9% by weight of a copolymer (a) selected from ethylene-vinyl acetate (EVA) copolymers, copolymers of ethylene and alkyl (meth)acrylates, and / or mixtures thereof, 0.1 to 40% by weight of a branched copolymer (b) containing polyamide blocks and polyether blocks, said copolymer (b) having a number-average functionality (Efn) greater than 2, wherein the Mw / Mn molar mass ratio is greater than or equal to 2.2, and the Mz / Mw molar mass ratio is greater than or equal to 1.8, - 0% to 50% by weight of polyolefin (c) and / or thermoplastic elastomeric polymer (d), relative to the total weight of the composition, - 0.01 to 2% by weight of a crosslinking agent, The total amount amounts to 100% by weight.

2. The composition of claim 1, wherein the number average functionality (Efn) is greater than or equal to 3.

3. The composition of claim 1, wherein the crosslinking agent is a peroxide.

4. The composition according to claim 1, wherein the composition comprises 50 to 99.9 wt% of copolymer (a).

5. The composition according to claim 4, wherein the composition comprises 60 to 99.9 wt% of copolymer (a).

6. The composition according to claim 5, wherein the composition comprises 70 to 99.9 wt% of copolymer (a).

7. The composition of claim 1, wherein the composition comprises 0.1 to 30 wt% of the branched copolymer (b).

8. The composition according to claim 1, wherein the composition comprises from 0.1% to 40% by weight of polyolefin (c) and / or thermoplastic elastomeric polymer (d), relative to the total weight of the composition.

9. The composition according to claim 8, wherein the composition comprises from 0.1% to 30% by weight of polyolefin (c) and / or thermoplastic elastomeric polymer (d), relative to the total weight of the composition.

10. The composition according to claim 9, wherein the composition comprises from 0.1% to 20% by weight of polyolefin (c) and / or thermoplastic elastomeric polymer (d), relative to the total weight of the composition.

11. The composition according to any one of claims 1 to 10, wherein the branching of the copolymer (b) is carried out by binding of polyol residues to the polyamide blocks of the copolymer (b), the polyol being a polyol comprising at least three hydroxyl groups.

12. The composition according to any one of claims 1 to 10, wherein the branching of the copolymer (b) is carried out by binding of polyepoxide compound residues to the polyamide blocks of the copolymer (b), the polyepoxide compound being a polyepoxide compound comprising at least three epoxide functions.

13. The composition according to any one of claims 1 to 10, wherein the polyamide blocks of the copolymer (b) comprise polyamide blocks selected from the group consisting of PA 6, 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 6.9, 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 10.4, PA 10.9, PA 10.10, PA 10.12, PA 10.13, PA 10.14, PA 10.16 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, PA6 / 12, PA11 / 12, PA11 / 10.10, or mixtures or copolymers thereof.

14. The composition according to any one of claims 1 to 10, wherein the polyether blocks of the copolymer (b) are selected from PEG blocks, and / or PPG blocks, and / or PO3G (polytrimethylene glycol) blocks, and / or PTMG blocks.

15. The composition according to any one of claims 1 to 10, wherein the weight average molar mass (Mw) of the copolymer (b) is greater than 80 000 g / mol.

16. The composition according to claim 15, wherein the weight average molar mass (Mw) of the copolymer (b) is from 80 000 to 300 000 g / mol.

17. The composition according to claim 16, wherein the weight average molar mass (Mw) of the copolymer (b) is from 90 000 to 250 000 g / mol.

18. The composition according to claim 17, wherein the weight average molar mass (Mw) of the copolymer (b) is from 100,000 to 200,000 g / mol.

19. The composition of claim 1, wherein the Mw / Mn molar mass ratio is greater than or equal to 2.

4.

20. The composition of claim 1, wherein the Mz / Mw molar mass ratio is greater than or equal to 2.

0.

21. The composition according to any one of claims 1 to 10, wherein the polyolefin (c) is a functionalized polyolefin (c1 ).

22. The composition according to any one of claims 1 to 10, wherein the thermoplastic elastomeric polymer (d) is selected from copolymers containing polyester blocks and polyether blocks, thermoplastic polyurethanes, olefinic thermoplastic elastomers or olefinic block copolymers, styrene-diene block copolymers, and / or mixtures thereof.

23. Foam formed based on the composition according to any one of claims 1 to 22.

24. A method for preparing a composition according to any one of claims 1 to 22, comprising: (i) providing a mixture comprising: - copolymer (a), - copolymer (b), - a cross-linking agent, and - optionally a polyolefin (c), a thermoplastic elastomeric polymer (d) and at least one additive; (ii) A step of shaping the mixture by injection molding, compression / molding or extrusion.

25. The method of claim 24, wherein the cross-linking agent is a peroxide.

26. A method for preparing the foam according to claim 23, comprising: (i) providing a mixture comprising: - copolymer (a), - copolymer (b), - a cross-linking agent, - a blowing agent, and - optionally a polyolefin (c), a thermoplastic elastomeric polymer (d) and at least one additive; (ii) shaping the mixture by injection molding, compression / molding or extrusion; (iii) a step of foaming the mixture.

27. The method of claim 26, wherein the cross-linking agent is a peroxide.

28. The method of claim 26, wherein the blowing agent is a chemical blowing agent.

29. The method of claim 26, wherein step (i) is performed by mixing in a molten state: - 30% to 99.9% by weight of copolymer (a); - 0.1 to 50% by weight of copolymer (b); - 0 to 50% by weight of polyolefins (c) and / or thermoplastic elastomeric polymers (d); - 0% to 20% by weight of at least one additive; - 0.01 to 2% by weight of a crosslinking agent; - 0.5 to 10% by weight of a blowing agent, The total amount amounts to 100% by weight of the mixture.

30. The method according to claim 29, wherein the amount of copolymer (b) is from 0.1 wt% to 40 wt%.

31. The method of claim 29, wherein the at least one additive is present in an amount of 0.1 wt% to 20 wt%.

32. The method of claim 29, wherein the crosslinking agent is a peroxide.

33. The method of claim 29, wherein the blowing agent is a chemical blowing agent.

34. Composition obtainable according to the method of any one of claims 24 to 25.

35. Foam obtainable according to the process of any one of claims 26 to 33.

36. Article comprising at least one element consisting of a composition according to any one of claims 1 to 22, or 34, or At least one element consisting of a foam according to claim 23 or 35.

37. The article of claim 36 selected from the group consisting of shoe soles, large or small balls, gloves, personal protective equipment, track pads, automotive parts, building parts, and electrical and electronic equipment parts.

38. The article of claim 37, wherein the sole is a sports shoe sole.

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