Copolymers containing polyamide blocks and polyether blocks for producing foamed articles - Patents.com

Abstract

The present invention relates to a copolymer having a polyamide block and a polyether block (PEBA), which can be used for the manufacture of articles, preferably foamed articles. The present invention also relates to expanded beads prepared from said copolymer and the manufacture of expanded articles from said expanded beads.

Description

[Technical field]

[0001] The present invention relates to a copolymer having a polyamide block and having a polyether block (PEBA), which can be used for the manufacture of articles, preferably foamed articles. The present invention also relates to expanded beads prepared from said copolymer, and to the manufacture of expanded articles from the expanded beads. [Background technology]

[0002] It is known to use copolymers having polyamide blocks and having polyether blocks, and more advantageously foamed articles prepared from copolymers of this type, due to their mechanical properties and light weight, in the field of sports equipment, such as soles or sole components, gloves, rackets or golf balls, and in particular personal protective equipment for playing sports (jackets, interior parts of helmets, outer shells, etc.).

[0003] Foamed articles (also called "foamed articles") can be prepared by a variety of foaming techniques, including injection molding or extrusion processes, "autoclave" processes, or techniques starting from foamed particles (foamed beads).

[0004] More specifically, the preparation of the expanded beads can be carried out according to different methods, for example: The document US 2016 / 0121524 describes an "expansion-extrusion" method for producing expanded particles of thermoplastic elastomers, which comprises the step of extrusion of a molten thermoplastic elastomer with a physical blowing agent such as CO2 or N2; The document US 2016 / 0297943 describes a method for producing expanded beads by the "autoclave" method, which comprises the steps of impregnating granules of a thermoplastic elastomer in a gaseous medium at a specific temperature and a specific pressure, and blowing at a reduced pressure relative to the pressure applied during the impregnation step.

[0005] The manufacture of expanded, often molded, articles starting from expanded particles generally involves assembling these expanded particles by fusion as described in WO 16030333, which are joined together in a mould by supplying thermal energy to obtain an expanded and moulded article (e.g. a sole for footwear). This supply of thermal energy can be provided by a stream of pressurised steam, electromagnetic radiation or microwave radiation. Under the influence of pressure and temperature, the expanded particles partially melt at the surface, allowing interdiffusion of the polymer chains between neighbouring expanded particles and thus ensuring their adhesion. To ensure good mechanical properties of the expanded and moulded article, good cohesion of the expanded particles and a low content of macrovoids are also necessary.

[0006] EP 3053732 describes a method for producing foamed articles by assembling foamed particles under electromagnetic radiation.

[0007] However, preparing foamed articles from foamed beads is not always easy, especially when the assembly of these foamed beads is carried out by molding, because during molding, the foamed beads are not always able to perfectly match the shape of the mold, especially when the shape is complex.

[0008] To try to solve this problem, high pressure can be applied to "force" the expanded particles to conform to the shape of the mold, but this generally results in an increase in density and a destruction of the good mechanical strength of the molded article as a result of crushing of the expanded particles during assembly. It is also possible to increase the temperature to further melt the particles, but this generally induces surface defects in the molded article.

[0009] Document JP2016188342 describes an article foamed by molding. It states that the fusion between foamed particles can be improved by reducing the crystallinity of the surface layer of the particles. For this purpose, the surface of the particles is impregnated with a crystallinity inhibitor of the phenolic compound type.

[0010] There is a continuing demand in the market for lighter, more efficient foamed articles, i.e., foamed articles having improved properties in terms of density and uniformity, while maintaining the mechanical properties required for the end use.

[0011] It is therefore an object of the present invention to provide copolymers having polyamide blocks and having polyether blocks, which preferably make it possible to prepare from the expanded beads produced therefrom expanded articles having low density, improved homogeneity and good mechanical properties, such as rebound capacity, low compression set, ability to withstand repeated impacts without deformation and ability to return to their original shape. Summary of the Invention

[0012] According to a first aspect, the invention relates to a copolymer having polyamide blocks and having polyether blocks (PEBA) and suitable for the preparation of expanded beads, comprising: - a crystallinity such that the enthalpy of fusion, measured by DSC during the second heating at a rate of 20 ° C. / min according to the ISO 11357-3 standard (ΔHm(2)), is greater than or equal to 15 J / g, this melt exhibiting a crystallinity that is that of amide units, - exhibiting a Vicat softening temperature (VST) according to ISO 306 standard (method A50) of 75 ° C or higher and 120 ° C or lower, Concerning copolymers.

[0013] The present invention provides certain copolymers that are uniform and homogeneous, exhibit low density, and allow for the formation of foamed articles from said copolymers having one or more advantageous properties among which are high ability to recover elastic energy during low stress loading, low compression set (hence improved durability), high compressive fatigue strength, excellent elastic properties, and especially abrasion resistance.

[0014] The fusion enthalpy is preferably 18 J / g or more, more preferably 20 J / g or more.

[0015] The Vicat softening temperature is preferably 80° C. or higher, more preferably 90° C. or higher, and preferably 115° C. or lower, more preferably 110° C. or lower.

[0016] According to one embodiment, the polyamide blocks of the PEBA copolymer are copolyamide blocks.

[0017] According to one embodiment, the polyamide blocks of the PEBA copolymer are chosen from polyamide blocks resulting from the condensation of α,ω-aminocarboxylic acids or lactams, preferably from PA11 or PA12 blocks, said copolymers having a number average molar mass (Mn) of the polyamide blocks of 400 to 1500 g / mol, more preferentially from 500 to 1200 g / mol and more preferentially even from 500 to 1000 g / mol and / or a number average molar mass (Mn) of the polyether blocks of 400 to 2000 g / mol, more preferentially from 500 to 1500 g / mol and more preferentially even from 500 to 1000 g / mol.

[0018] The copolymer may have an instantaneous hardness of 72 Shore D or less, more preferably 55 Shore D or less, and more preferably less than 45 Shore D.

[0019] According to another aspect, the present invention relates to expanded beads of a copolymer as described below.

[0020] In the context of the present invention, it has been observed that during the stage of assembly by molding, these particular expanded particles easily adapt to the shape of the mold, making it possible to prepare expanded articles of complex shape.

[0021] Accordingly, the present invention provides expanded beads made from specific PEBA copolymers that have improved moldability for the production of foamed articles by molding, while retaining the required good mechanical properties and improved light weight as described above.

[0022] According to another aspect, the present invention relates to an article, preferably an expanded article, comprising at least one element consisting of the PEBA copolymer defined above or the expanded particles described above.

[0023] The article may be selected from footwear soles, in particular sports footwear soles, large or small balls, gloves, personal protective equipment, tie pads, automotive parts, structural parts and electrical and electronic equipment parts.

[0024] The present invention also relates to a method for preparing a foamed article by molding, comprising the step of assembling the foamed particles in a mold.

[0025] The invention will now be described in non-limiting detail in the following description. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] definition The present invention includes the following examples. - Vicat softening temperature (VST) is measured according to the ISO 306:2013 standard (method A50). The density of the expanded particles or expanded articles is measured according to the ISO 845:2009 standard. The number-average molar mass Mn is measured by size-exclusion chromatography (or gel permeation chromatography) according to ISO 16014-1:2012. The product is solubilized in hexafluoroisopropanol stabilized with 0.05 M potassium trifluoroacetate at a concentration of 1 g / l for 24 hours at room temperature. The resulting solution is subsequently filtered through a PTFE membrane with a porosity of 0.2 μm and then injected at a flow rate of 1 ml / min into a liquid chromatography system equipped with a set of PFG columns from Polymer Standards Service consisting of a precolumn with dimensions of 50×8 mm, a 1000 Å column with dimensions of 300×8 mm and a particle size of 7 μm, and a 100 Å column with dimensions of 300×8 mm and a particle size of 7 μm. The molar mass is measured by refractive index and expressed as PMMA equivalent (PMMA is used as a calibration standard). The instantaneous hardness of PEBA copolymers is measured according to the ISO 868:2003 standard. - The ball rebound resilience of foamed articles is measured according to the ISO 8307:2007 standard; The compression set of the foamed article is measured according to the ISO 7214:2012 standard, with a deformation of 50% and a maintenance time of 6 hours at a temperature of 50°C, a first measurement after 30 minutes and a second measurement after 24 hours of recovery. - the nomenclature used to designate polyamides follows the ISO 1874-1 standard. In particular, in the PA "Z" designation, Z represents the number of carbon atoms of the polyamide unit resulting from the condensation of an amino acid or a lactam. In the PA "XY" designation, which represents a polyamide resulting from the condensation of a diamine with a dicarboxylic acid, X represents the number of carbon atoms of the diamine and Y represents the number of carbon atoms of the dicarboxylic acid. The designations PAZ / XY, PAZ / Z', PAZ / XY / X'Y', PAZ / Z' / XY, PAZ / Z' / XY / X'Y' etc. are such that XY, Z, X'Y', Z' etc. represent the XY or Z homopolyamide units as defined above, with X'Y' being the same or different from XY and Z' being the same or different from Z, for copolyamides, - The D50 size, referred to herein as "Volume Median Diameter", is measured according to the ISO 9276-2:2014 standard.

[0027] Copolymer with polyamide blocks and polyether blocks (PEBA) The copolymer having a polyamide block and having a polyether block of the present invention may preferably be a linear (non-crosslinked) copolymer.

[0028] The PEBA copolymer is a copolymer of a polyamide (PA) block having a reactive end and a polyether (PE) block having a reactive end, e.g. 1) polyamide blocks having diamine chain ends and polyoxyalkylene blocks having dicarboxyl chain ends; 2) polyamide blocks having dicarboxyl chain ends and polyoxyalkylene blocks having diamine chain ends; 3) It may result from the polycondensation of polyamide blocks having dicarboxyl chain ends with polyether diols, the resulting products being, in this particular case, polyether ester amides.

[0029] Polyamide blocks with dicarboxyl chain ends result, for example, from the condensation of polyamide precursors in the presence of chain-limiting dicarboxylic acids. Polyamide blocks with diamine chain ends result, for example, from the condensation of polyamide precursors in the presence of chain-limiting diamines.

[0030] Two types of polyamide blocks can be advantageously used.

[0031] According to the first type (PAZ / XY, PAZ / Z', PAZ / XY / X'Y', PAZ / Z' / XY, PAZ / Z' / XY / X'Y', etc. type), the polyamide blocks are copolyamide blocks.

[0032] These blocks can be obtained, for example, by condensation of one or more α,ω-aminocarboxylic acids or lactams with at least one diamine and at least one dicarboxylic acid.

[0033] According to another embodiment, the polyamide blocks result from the condensation of at least two α,ω-aminocarboxylic acids or at least two lactams having 6 to 12 carbon atoms or a lactam with an α,ω-aminocarboxylic acid having a different number of carbon atoms.

[0034] As examples of α,ω-aminocarboxylic acids, mention may be made of α,ω-aminocarboxylic acids having 4 to 12 carbon atoms, in particular aminocaproic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid and 12-aminododecanoic acid.

[0035] As examples of lactams, mention may be made of lactams having 6 to 12 carbon atoms, in particular caprolactam, oenantholactam and lauryllactam. Particular preference is given to PA6, PA11 and PA12 blocks, and mixtures thereof.

[0036] As examples of dicarboxylic acids, the dicarboxylic acid may contain from 4 to 36, preferably from 6 to 18, carbon atoms. It is preferably an aliphatic, in particular a linear, alicyclic or aromatic dicarboxylic acid.

[0037] Preferably, it is an aliphatic, in particular linear dicarboxylic acid. As examples, mention may be made of butanedioic acid, adipic acid, azelaic acid, suberic acid, sebacic acid, dodecanedicarboxylic acid, octadecanedicarboxylic acid, terephthalic acid and isophthalic acid, and dimerized fatty acids. These dimerized fatty acids preferably have a dimer content of at least 98%, and preferably they are hydrogenated, such as the products sold under the trademark Pripol® by Croda, or under the trademark Empol® by BASF, or under the trademark Radiacid® by Oleon, and polyoxyalkylene-α,ω-dioic acids.

[0038] As examples of diamines, the diamines may in particular contain from 2 to 20, preferably from 6 to 14 carbon atoms. As examples, mention may be made of tetramethylenediamine, 1,5-pentanediamine, 2-methylpentane-1,5-diamine, hexamethylenediamine, 1,10-decamethylenediamine, dodecamethylenediamine, trimethylhexamethylenediamine, bis(4-aminocyclohexyl)methane (BACM), bis(3-methyl-4-aminocyclohexyl)methane (BMACM), and 2,2-bis(3-methyl-4-aminocyclohexyl)propane (BMACP), and isomers of paraaminodicyclohexylmethane (PACM), isophoronediamine (IPDA), 2,6-bis(aminomethyl)norbornane (BAMN), and piperazine (Pip).

[0039] The homopolyamide units (of PA "XY" type) derive from the condensation of dicarboxylic acids with aliphatic, cycloaliphatic or aromatic diamines, preferably aliphatic diamines.

[0040] Also preferred are PA66, PA610, PA612, PA1010, PA1012, PA1014, and mixtures thereof.

[0041] According to this first type, particular preference is given to the PA6 / 11, PA6 / 12, PA11 / 12, PA6 / 11 / 12, PA6 / 66 / 12, PA6 / 1010, PA6 / 1012, PA6 / 1010 / 1012, PA6 / 1012 / 12, PA6 / 66 / 11 / 12 and PA6 / 1010 / 1012 / 1014 blocks, and mixtures thereof.

[0042] According to a second type, the polyamide blocks (of PA "Z" type) result from the condensation of α,ω-aminocarboxylic acids or of lactams.

[0043] The α,ω-aminocarboxylic acids and lactams may in particular be chosen from those listed above for the polyamide blocks of the first type. PA11 and PA12 blocks are particularly preferred.

[0044] These polyamide blocks can be prepared by polycondensation of monomers in the presence of suitable chain limiters. Such chain limiters are, for example, the dicarboxylic acids and diamines mentioned above. Thereby, the dicarboxylic acids or diamines used as monomers, introduced in excess, can be used as chain limiters. In the case of polycondensation of α,ω-aminocarboxylic acids or lactams, the chain limiter can be added to the monomers. Dimerized fatty acids can also be mentioned. These dimerized fatty acids preferably have a dimer content of at least 98%, preferably they are hydrogenated, for example the products sold under the trademark Pripol® by Croda, or under the trademark Empol® by BASF, or under the trademark Radiacid® by Oleon, and polyoxyalkylene-α,ω-diacids.

[0045] The polyether blocks of the PEBA essentially comprise or consist of alkylene oxide units, and may originate from alkylene glycols such as PEG (polyethylene glycol), PPG (polypropyl glycol), PO3G (polytrimethylene glycol) or PTMG (polytetramethylene glycol), preferably PTMG.

[0046] They may also result from copolyethers which contain different alkylene oxides distributed uniformly in the chain, in particular in blocks, or randomly.

[0047] Polyether blocks can also be obtained by oxyethylation of bisphenols, such as bisphenol A. These products are described, inter alia, in document EP 613919.

[0048] The polyether blocks may also be ethoxy primary amines, such as the products of the formula: In the formula TIFF2024507310000001.tif46170, m and n are integers from 1 to 20, and x is an integer from 8 to 18.

[0049] These products are commercially available, for example, from CECA under the trade name Noramox® and from Clariant under the trade name Genamin®.

[0050] The polyether blocks may ultimately comprise or consist of polyoxyalkylene blocks with NH2 chain ends, such blocks being obtainable by cyanoacetylation of polyether diols. Such polyethers are sold under the names Jeffamine® or Elastamine® by Huntsman (e.g. Jeffamine® D400, D2000, ED2003 or XTJ542).

[0051] A two-step process for the preparation of PEBAs having ester bonds between the PA and PE blocks is described in document FR 2846332. A process for the preparation of PEBAs having amide bonds between the PA and PE blocks is described in document EP 1482011. To prepare PEBAs by a one-step process, the polyether blocks can also be mixed with the polyamide precursor and the diacid chain limiter.

[0052] PEBAs generally include polyamide blocks and polyether blocks, but may also include two, three, four, or indeed more different blocks selected from those listed.

[0053] According to one embodiment, preferred PEBA copolymers are copolymers comprising a copolyamide block and a block resulting from PTMG, for example a block resulting from PA6 / 11 and PTMG, a block resulting from PA6 / 12 and PTMG, a block resulting from PA11 / 12 and PTMG, a block resulting from PA6 / 11 / 12 and PTMG, a block resulting from PA6 / 66 / 12 and PTMG, a block resulting from PA6 / 1010 and PTMG, a block resulting from PA6 / 1012 and PTMG, a block resulting from PA6 / 1010 / 1012 and PTMG, or a block resulting from PA6 / 1012 / 12 and PTMG.

[0054] According to an embodiment in which the polyamide blocks of the PEBA copolymer are copolyamide blocks, the number average molar mass (Mn) of the polyamide blocks in the PEBA copolymer is between 400 and 20 000 g / mol, more preferentially between 500 and 10 000 g / mol, preferentially between 500 and 4 000 g / mol and more preferentially even between 600 and 2 000 g / mol. For example, the number average molar mass of the polyamide block in the PEBA copolymer is 400 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 It may be 9000g / mol, or 9000-10000g / mol, or 10000-11000g / mol, or 11000-12000g / mol, or 12000-13000g / mol, or 13000-14000g / mol, or 14000-15000g / mol, or 15000-16000g / mol, or 16000-17000g / mol, or 17000-18000g / mol, or 18000-19000g / mol, or 19000-20000g / mol.

[0055] According to this embodiment, the number average molar mass (Mn) of the polyether blocks is between 100 and 6000 g / mol, more preferentially between 200 and 3000 g / mol and even more preferentially between 200 and 2000 g / mol. The number average molar mass of the polyether blocks can be 100-200 g / mol, or 200-500 g / mol, or 500-800 g / mol, or 800-1000 g / mol, or 1000-1500 g / mol, or 1500-2000 g / mol, or 2000-2500 g / mol, or 2500-3000 g / mol, or 3000-3500 g / mol, or 3500-4000 g / mol, or 4000-4500 g / mol, or 4500-5000 g / mol, or 5000-5500 g / mol, or 5500-6000 g / mol.

[0056] According to an embodiment in which the polyamide blocks of the PEBA copolymer are selected from polyamide blocks resulting from the condensation of α,ω-aminocarboxylic acids (of PA “Z” type) or lactams, the number-average molar mass (Mn) of the polyamide blocks in the PEBA copolymer is preferably between 400 and 1500 g / mol, more preferentially between 500 and 1200 g / mol, and preferentially between 500 and 1000 g / mol. For example, the number-average molar mass (Mn) of the polyamide blocks in the PEBA copolymer can be between 400 and 600 g / mol, or between 600 and 900 g / mol, or between 900 and 1000 g / mol, or between 1000 and 1200 g / mol, or between 1200 and 1300 g / mol, or between 1300 and 1400 g / mol, or between 1400 and 1500 g / mol.

[0057] According to this embodiment, the number average molar mass (Mn) of the polyether blocks is preferably between 400 and 1500 g / mol, more preferentially between 500 and 1200 g / mol, even more preferentially between 500 and 1000 g / mol. For example, the number average molar mass of the polyether blocks can be between 400 and 600 g / mol, or between 600 and 900 g / mol, or between 900 and 1000 g / mol, or between 1000 and 1200 g / mol, or between 1200 and 1300 g / mol, or between 1300 and 1400 g / mol, or between 1400 and 1500 g / mol.

[0058] According to this embodiment, preferred PEBA copolymers are copolymers comprising a polyamide block resulting from the condensation of an α,ω-aminocarboxylic acid or a lactam and a block resulting from PTMG, e.g., a block resulting from PA11 and PTMG, a block resulting from PA12 and PTMG, and mixtures thereof.

[0059] The number-average molar mass (Mn) is set by the content of chain limiter, which can be calculated according to the following relationship: M n =n モノマー xM w繰返し単位 / n 鎖制限剤 +Mw鎖制限剤

[0060] In this formula, n モノマー represents the number of moles of monomer, and n 鎖制限剤 represents the number of moles of excess chain limiter (e.g., diacid), and M w繰返し単位 represents the molar mass of the repeating unit, M w鎖制限剤 represents the molar mass of the excess chain limiter (e.g. diacid).

[0061] According to one embodiment, the proportion by weight of polyether blocks in the copolymer is at least 50% relative to the total weight of the copolymer.

[0062] Preferably, the proportion by weight of the polyether blocks is between 55% and 85% relative to the total weight of the copolymer, and more preferentially between 60% and 80% relative to the total weight of the copolymer.

[0063] The weight proportion of a block in a copolymer can be determined from the number average molar mass of the block.

[0064] The PEBA copolymers of the present invention can contain at least one conventional additive, such as heat stabilizers (e.g., antioxidants, UV stabilizers), glass fibers, carbon fibers, flame retardants, talc, nucleating agents, plasticizers, colorants, fluorinating agents, lubricants, or stearates, such as zinc stearate, calcium stearate, or magnesium stearate.

[0065] The PEBA copolymer may be derived at least in part from bio-based feedstocks.

[0066] The term "raw materials of renewable origin" or "bio-based raw materials" is understood to mean materials that contain bio-based carbon or carbon of renewable origin. In particular, materials that consist of renewable starting materials, as opposed to materials obtained from fossil materials. 14"Renewable carbon content" or "bio-based carbon content" is determined by application of the ASTM D6866 standard (ASTMD6866-06) and the ASTM D7026 standard (ASTMD7026-04). As an example, PEBA with PA11 blocks is derived at least in part from bio-based raw materials and contains at least 1.2 × 10 -14 of 12 C / 14 The PEBA exhibits a biobased carbon content of at least 1% corresponding to the C isotope ratio. Preferably, the PEBA contains at least 50% by weight of biobased carbon based on the total weight of carbon, which is at least 0.6×10 -12 of 12 C / 14 This content is advantageously higher, in particular up to 100%, which is, for example, 1.2×10 for PEBA with PA11 blocks and PE blocks with PTMG obtained from raw materials of renewable origin. -12 of 12 C / 14 Corresponds to the C isotope ratio.

[0067] Expanded particles Copolymers having polyamide blocks and having polyether blocks as defined above can be used to prepare expanded beads.

[0068] The expanded beads according to the invention preferably have a compressive strength of 200 kg / m 3 Less than or equal to 150 kg / m 3 Below, more preferentially 100kg / m 3 It exhibits the following densities: Control of density can be achieved by the skilled artisan by adapting the parameters of the manufacturing process.

[0069] The expanded particles may contain one or more polymers other than the abovementioned PEBA copolymers, such as polyamides, functional polyolefins, copolyetheresters, thermoplastic polyurethanes (TPUs), copolymers of ethylene and vinyl acetate (such as the products sold under the trademark Evatane® by SK Functional Polymer), or copolymers of ethylene and acrylates, or copolymers of ethylene and alkyl (meth)acrylates (such as the products sold under the trademark Lotryl® by SK Functional Polymer). These additives may make it possible to adjust the hardness of the particles, their appearance and their comfort. The additives may be added in a content of 0% to 50% by weight, preferentially 5% to 30% by weight, relative to the total weight of the PEBA copolymer.

[0070] The expanded particles may also contain one or more additives such as pigments (TiO2 and other compatible color pigments), adhesion promoters (to improve the adhesion of the expanded foam to other materials), fillers (e.g., calcium carbonate, barium sulfate, and / or silicon oxide), nucleating agents (in pure or concentrated form, e.g., CaCO3, ZnO, SiO2, or combinations of two or more thereof), rubbers (to improve the rubber elasticity of natural rubber, SBR, polybutadiene, and / or ethylene / propylene terpolymers, etc.), stabilizers such as antioxidants, UV absorbers, and / or flame retardants, and processing aids such as stearic acid. The additives may be added preferably in a content of 0% to 10% by weight, based on the total weight of the PEBA copolymer.

[0071] The expanded particles according to the invention can be used for producing sports equipment such as sports footwear soles, ski footwear, midsoles, insoles or other functional sole components in the form of inserts in various parts of the sole (for example heel or arch) or other footwear upper components in the form of reinforcement or in the form of inserts into the structure of the footwear upper in the form of protection.

[0072] They can also be used to manufacture big balls, sports gloves (eg football gloves), golf ball components, rackets, protective elements (jackets, helmet interiors, outer shells, etc.).

[0073] They can also be used in the manufacture of railway tie pads, or various parts in the automotive industry, transportation, electrical and electronic equipment, building industry or manufacturing industry.

[0074] The expanded beads can be prepared according to methods known to those skilled in the art.

[0075] By way of example, the expanded particles can be prepared by a manufacturing process that includes an impregnation step and a blowing step.

[0076] The impregnation step can be carried out in an autoclave in water, in which the PEBA copolymer as defined above in the form of granules is mixed with a dispersing agent, optionally one or more polymers other than the PEBA copolymer and / or one or more of the additives mentioned above ("wet impregnation"). Then, typically under stirring at temperature and pressure, a blowing agent is introduced into the dispersion under pressure, in order to obtain a dispersion, thus impregnating the blowing agent into the granules of the copolymer.

[0077] The dispersing agent may be a surfactant such as calcium phosphate, magnesium pyrophosphate, sodium pyrophosphate and magnesium oxide, or sodium dodecylbenzenesulfonate.

[0078] Alternatively, the impregnation step can be carried out by introducing the blowing agent under pressure into the granules of the copolymer in an autoclave ("dry impregnation") to obtain granules impregnated with the blowing agent.

[0079] The blowing step generally includes a pressure reduction step that allows the gas produced by the blowing agent to dissipate in order to produce expanded particles of the copolymer.

[0080] The expanded particles can also be prepared by an extrusion process, which comprises a step of melt extrusion of a mixture of the PEBA copolymer as defined above in the form of granules, and optionally one or more polymers other than the PEBA copolymer and / or one or more additives as described above, a blowing agent bringing about the expansion of said mixture directly at the extrusion die outlet, for example in an extruder, and the expanded particles can be recovered in cooling water during granulation.

[0081] The blowing agent may be a chemical or physical agent, or a mixture thereof.

[0082] Preferably, it is a physical agent, for example, an aliphatic hydrocarbon such as butane, an alicyclic hydrocarbon such as cyclobutane, and an inorganic gas such as carbon dioxide, nitrogen and air.

[0083] The physical blowing agent may be mixed with the copolymer in liquid or supercritical form and then converted to the gas phase during the foaming stage. The physical blowing agent may remain present within the pores of the foam and / or may dissipate, especially if it is a closed cell foam.

[0084] Chemical blowing agents are agents that generate gas by chemical reaction or thermal decomposition. Examples include azodicarbonamide or mixtures based on citric acid and sodium bicarbonate (NaHCO3) (e.g. products sold under the trade name Hydrocerol® by Clariant).

[0085] The expanded beads thus formed essentially consist, and in fact even consist, of the above-mentioned copolymer (or mixture, if a mixture of polymers is used) and optionally one or more additives dispersed in the matrix. When a chemical blowing agent is used, the foamed article may contain, in addition to the above-mentioned copolymer (or mixture, if a mixture of polymers is used), decomposition products of the chemical blowing agent, which are dispersed in the matrix.

[0086] The expanded beads can typically have a spherical, elliptical or triangular shape. Preferably, the expanded beads have a spherical shape, which can have an average size D50 of 2 to 20 mm, preferably 2 to 10 mm.

[0087] The expanded beads of the invention can be recycled, for example, by melting them (optionally after chopping into small pieces) in an extruder equipped with a degassing outlet.

[0088] Goods The article, preferably a foamed article, comprises at least one element consisting of the PEBA copolymer defined above or the foamed particles described above.

[0089] The articles, preferably foam articles, may be selected in the form of protection for sports equipment such as sports footwear soles, ski footwear, midsoles, insoles or other functional sole components in the form of inserts in various parts of the sole (e.g. heel or arch) or to reinforce other footwear upper components or in the form of inserts into the structure of the footwear upper.

[0090] It may also be selected from a ball, a sports glove (for example a football glove), a golf ball component, a racket, a protective element (exterior covering, inner part of a helmet, outer shell, etc.), a railway tie pad, or various parts of the automotive industry, the transport, the electrical and electronic equipment, the building industry or the manufacturing industry.

[0091] According to one embodiment, the article, preferably the foam article, is selected from footwear soles, in particular sports footwear soles, large or small balls, gloves, personal protective equipment, tie pads, automotive parts, structural parts and electrical and electronic equipment parts.

[0092] The article, preferably the foamed article, may comprise one or more polymers other than the PEBA copolymer and / or one or more additives selected from those listed above, especially for the foamed particles.

[0093] The foamed article of the present invention preferably has a strength of 200 kg / m 3 Less than or equal to 180 kg / m 3 Less than or equal to 150 kg / m 3 It exhibits a density of: Preferably, the foamed article exhibits a resilience with ball rebound of at least 50%, preferably at least 60%.

[0094] Preferably, the foamed article exhibits a compression set of 50% or less, more particularly preferably 45% or less, or 40% or less, or 35% or less.

[0095] Another advantage of the articles of the present invention, preferably foam articles, is that they provide better adhesion to other elements to facilitate complex assemblies, which is particularly advantageous in the manufacture of multi-layer structures by overmolding methods, for example in the context of making footwear soles, which are often in the form of multiple layers.

[0096] The foamed articles of the present invention can be prepared preferably by molding processes, for example by compression molding of foamed particles or by injection molding starting from the copolymer in granular form.

[0097] According to one embodiment, the foamed article of the present invention is prepared by congregating the foamed particles described above in a mold.

[0098] The assembly step can be accomplished by thermocompression bonding using a hot press and / or steam chest compression molding of the expanded particles in a mold.

[0099] Reference may be made to the article "Past and present developments in polymer bead foams and bead foaming technology" by Daniel Raps et al. (Polymer, 56 (2015) 5-19). The steam pressure and / or temperature conditions depend on the PEBA copolymer that constitutes the foamed beads and can be adjusted by those skilled in the art.

[0100] A binder may be used to facilitate assembly of the foam particles. Examples of binders include surface modifiers such as urethane. These binders may be used alone or in combination. Preferably, a binder is used during hot pressing.

[0101] According to a preferred embodiment, the preparation of the expanded beads and the preparation of the expanded article from the expanded beads can be carried out in one and the same facility, preferably in a mould.

[0102] Thus, the method for preparing a foamed article comprises: - impregnation in a mold of said PEBA copolymer in the form of granules with a blowing agent, optionally with one or more polymers other than the copolymer and / or with one or more additives; - a blowing step for producing foamed copolymer particles; and - assembling the foamed particles to form a foamed article in a mold, the blowing and assembling steps being performed simultaneously. Includes.

[0103] The present invention is particularly directed to the preparation of foamed articles by assembling foamed particles, however, it would not depart from the scope of the invention to prepare foamed articles by foam injection molding starting from PEBA copolymers in granular form.

[0104] The method can include injecting a mixture comprising a PEBA copolymer as defined above, in the form of granules, optionally one or more polymers other than a PEBA copolymer, and / or one or more additives and blowing agents as described above, into a mold and foaming the mixture.

[0105] The foaming is produced during the injection of a volume of polymer into the mold that is smaller than the volume of the mold, or by the opening of the mold. These two techniques, either separately or in combination, make it possible to produce three-dimensional foam objects with complex geometric shapes directly from copolymer granules.

[0106] Other foam injection molding techniques that can be used in the context of the present invention are foam injection molding using breathing molds, in particular with the application of gas back pressure, under metering, or using molds equipped with a Variotherm® system.

[0107] The foamed article according to the invention can be recycled (optionally after shredding), for example by melting it in an extruder equipped with a degassing outlet.

[0108] The invention will now be further illustrated, in a non-limiting manner, with the aid of the following examples. EXAMPLES

[0109] Example 1 Materials used: Table 1 shows the different raw materials used and their respective suppliers. All compounds were used as received. TIFF2024507310000002.tif47170

[0110] The compounds PTMG650, PTMG1000 and PTMG2000 are products sold under the names PolyTHF® 650, PolyTHF® 1000 and PolyTHF® 2000.

[0111] PEBA copolymers: Different PEBA copolymers were prepared. The properties and number average molar masses (Mn) of the polyamide (PA) and polyether (PE) blocks of Examples A to D and Counterexamples E to G are shown in Table 2 below. TIFF2024507310000003.tif72170

[0112] When the PA block is copolymerized, the weight ratio of each component of the amide unit is specified. For example, Example B refers to a PEBA copolymer in which the PA block is made of PA11 / 12 copolyamide (PA11 / 12 weight ratio).

[0113] Preparation method: PEBA copolymer was synthesized according to the following protocol.

[0114] For example A: 35.02 g of Amino 11, 9.25 g of adipic acid and 40 g of PTMG 650 are charged into a 300 ml glass tube connected to an anchor stirrer and a condenser. The assembly is inerted for 30 minutes under nitrogen flow and then heated to a temperature of 240 ° C. Stirring is started as soon as the reaction medium can be stirred. After 1 hour under nitrogen flow, the reaction medium is gradually placed under reduced pressure and the catalyst is introduced. The progress of the reaction is ensured by monitoring the motor torque, which is terminated when a torque of 20 N / cm is reached at 60 rpm. The vacuum is then interrupted and the stirring and heating are stopped. The reaction medium is subsequently placed under nitrogen while cooling. All syntheses are stabilized by 0.16 g of antioxidant and catalyzed by 0.59 ml of zirconium butoxide (Zr (OBu) 4 ) diluted in butanol.

[0115] Examples BG were prepared and adapted according to the protocol of Example A in the amounts shown in Table 3. TIFF2024507310000004.tif53170

[0116] Table 4 shows the Vicat softening temperatures (T VST ) and enthalpy of fusion, as well as the suitability of overmolding of foamed particles obtained from the PEBA copolymer in a method of assembly by steam chest compression molding.

[0117] The expanded beads are prepared according to the following method.

[0118] For Example F: 100 g of granules are impregnated with CO2 in an autoclave reactor at a pressure of 170 bar and a temperature of 135°C for 4 hours. This dry impregnation step is followed by a step of blowing in the gas dissolved in the PEBA resin by reducing the pressure to ambient pressure. After cooling the reactor, the expanded PEBA particles can be collected. The CO2 impregnation conditions depend on the copolymer that constitutes the expanded particles and can be adjusted by a person skilled in the art.

[0119] Examples A-E and G were prepared and adapted according to the protocol of Example F. TIFF2024507310000005.tif58170

[0120] Examples A-D and Counterexamples E-G show that PEBA copolymers exhibiting a Vicat softening temperature between 75° C. and 120° C. and a minimum crystallinity as defined by DSC measurement of the enthalpy of fusion of the amide units during a second heat at a rate of 20° C. / min, i.e., 15 J / g or greater, impart improved moldability to expanded beads made from the PEBA copolymers.

Claims

1. A copolymer having polyamide blocks and having polyether blocks (PEBA) and suitable for the preparation of expanded beads, - exhibits a crystallinity such that the enthalpy of fusion, measured by DSC during the second heating at a rate of 20 ° C. / min according to the ISO 11357-3 standard (ΔHm (2)), is greater than or equal to 15 J / g, this fusion being that of amide units; - exhibiting a Vicat softening temperature (VST) according to the ISO 306 standard (method A50) of 75 ° C. or more and 120 ° C. or less, Copolymer.

2. The copolymer of claim 1 , wherein the polyamide blocks of the PEBA copolymer are copolyamide blocks.

3. 3. The copolymer according to claim 1 or 2, wherein the polyamide blocks are selected from PA6 / 11, PA6 / 12, PA11 / 12, PA6 / 11 / 12, PA6 / 66 / 12, PA6 / 1010, PA6 / 1012, PA6 / 1010 / 1012, PA6 / 1012 / 12, PA6 / 66 / 11 / 12 and PA6 / 1010 / 1012 / 1014 blocks, and further mixtures thereof.

4. 2. Copolymer according to claim 1, in which the polyamide blocks of the PEBA copolymer are chosen from polyamide blocks resulting from the condensation of α,ω-aminocarboxylic acids or from the condensation of lactams, preferably from PA11 blocks or PA12 blocks, said copolymer having a number-average molar mass (Mn) of the polyamide blocks of 400 to 1500 g / mol, more preferentially from 500 to 1200 g / mol and even more preferentially from 500 to 1000 g / mol and / or a number-average molar mass (Mn) of the polyether blocks of 400 to 2000 g / mol, more preferentially from 500 to 1500 g / mol and even more preferentially from 500 to 1000 g / mol.

5. 5. Copolymer according to any one of claims 1 to 4, in which the polyether blocks are chosen from blocks obtained from PEG, from PPG, from PO3G and / or from PTMG, preferably from PTMG.

6. 6. The copolymer according to any one of claims 1 to 5, having an instantaneous hardness of 72 Shore D or less, more preferably 55 Shore D or less, more preferably 45 Shore D or less.

7. 7. The copolymer according to claim 1, wherein the proportion by weight of the polyether blocks in the copolymer is at least 50% relative to the total weight of the copolymer.

8. Expanded particles of the copolymer according to any one of claims 1 to 7.

9. 9. The expanded beads according to claim 8, having a spherical, elliptical or triangular shape, preferably spherical, with an average size between 2 and 20 mm.

10. 200 kg / m ３ Or better still, 150 kg / m ３ More preferably, 100 kg / m ３ 10. Expanded beads according to claim 8 or 9, exhibiting a density of:

11. 11. An article, preferably a foamed article, comprising at least one element consisting of the copolymer according to any one of claims 1 to 7 or the expanded particles according to any one of claims 8 to 10.

12. 12. The article according to claim 11, selected from footwear soles, in particular sports footwear soles, large or small balls, gloves, personal protective equipment, tie pads, automotive parts, structural parts and electrical and electronic equipment parts.

13. A method for making an article according to claim 11 or 12 by moulding.

14. 14. The method of claim 13, comprising assembling the expanded beads of any one of claims 8 to 10 by hot pressing using a hot press and / or steam chest compression molding in a mold.

15. - impregnation, in a mould, of the copolymer according to any one of claims 1 to 8, in the form of granules, with a blowing agent, optionally with one or more polymers other than said copolymer and / or with one or more additives; a blowing step to produce expanded beads of said copolymer; - assembling the foam particles to form a foamed article in a mold; Including, The blowing and assembly steps are performed simultaneously; The method of claim 13.

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