Peba for direct adhesion to TPU comprising hollow glass beads

Abstract

The present invention relates to an article comprising a first polymeric material having at least one polyamide PA block copolymer and PE polyether blocks (PEBA) and a second polymeric material having at least one thermoplastic polyurethane (TPU), wherein the first polymeric material directly adheres to the second adherent polymeric material, and wherein the second polymeric material comprises hollow glass beads. The present invention also relates to the assembly by a method of direct adhesion of the first polymeric material to the second polymeric material comprising hollow glass beads.

Description

[0001] PEBA for direct adhesion to TPU comprising hollow glass beads

[0002] Field of invention

[0003] The present invention relates to an article comprising a first polymer material comprising at least one copolymer with polyamide PA blocks and polyether PE blocks (PEBA) and a second polymer material comprising at least one thermoplastic polyurethane (TPU), the first polymer material adhering directly to the second polymer material, and the second polymer material comprising hollow glass beads. The present invention also relates to assembly by a method of direct adhesion of the first polymer material to the second polymer material comprising hollow glass beads.

[0004] Technical background

[0005] Materials based on thermoplastic elastomer (TPE) polymers, such as PEBA, TPU copolymers, or copolyether block esters (CoPE), are known for their use in the manufacture of automotive parts, sports equipment, including sports shoes, electrical and electronic equipment parts, medical equipment parts, etc.

[0006] The assembly of these materials of similar or different chemical natures and mechanical properties is sometimes required for these applications. The assembly can be carried out by molding or extrusion, possibly cutting the components, then gluing and pressing these components, or by direct adhesion process of these TPEs.

[0007] By "direct adhesion process" is meant an adhesion process without the addition of a binder, in particular without the addition of glue or adhesive, as glue or adhesive can be polluting and therefore more difficult to recycle. Compared to conventional bonding processes involving a multitude of complex steps generally using organic solvent-based adhesives, direct adhesion processes are more economical and non-polluting. Examples of direct adhesion processes include: overmolding, hot pressing, co-extrusion, thermoforming, co-injection, and any other possible adhesion method using one or more of the conventional methods such as injection molding, extrusion molding and / or blow molding. More specifically, the overmolding technique consists of injecting material onto an insert placed at the bottom of the mold.The adhesion of the two materials is achieved by the adhesive properties in the molten state and the compatibility of the overmolded material and the insert.

[0008] Unfortunately, the level of adhesion of TPE-based materials, systems obtained by direct adhesion, is not always optimal.

[0009] Additionally, these TPE-based materials can include additives and reinforcements, such as fibers and glass beads, for electronic, sports, automotive, or industrial applications to improve mechanical properties. In addition, the addition of hollow glass beads has been considered in the past, allowing for a lighter final product to be less energy-consuming or to minimize the energy expended during their use.

[0010] However, these additives and / or reinforcements can have adverse impacts, such as adhesion problems during their assembly. For example, in "Investigation of the interfacial adhesion of glass bead-filled multicomponent injection molded composites, Suplicz et al., IOP Conf.Series: Materials Science and Engineering 903 (2020)", a decrease in the adhesion strength between two overmolded materials including glass fibers or glass beads due to poor adhesion was observed.

[0011] There is therefore a real need to provide articles with good adhesion between these different materials including additives and / or reinforcements, in particular including hollow glass beads.

[0012] Summary of the invention

[0013] The invention firstly relates to an article comprising a first polymer material comprising at least one polyamide block and polyether block copolymer (PEBA) and a second polymer material comprising at least one thermoplastic polyurethane (TPU), the first polymer material adhering directly to the second polymer material, and the second polymer material comprising hollow glass beads.

[0014] According to one embodiment, the adhesion between two polymer materials, expressed by the peel force in kgf / cm, is greater than or equal to 10 kgf / cm, preferably greater than or equal to 12 kgf / cm.

[0015] According to one embodiment, the hollow glass beads have a content of 3 to 25% by weight relative to the total weight of the second polymer material.

[0016] According to one embodiment, the hollow glass beads comprise zinc oxide at a content greater than or equal to 1.0% by weight relative to the total weight of the hollow glass beads, and preferably greater than or equal to 2.0% by weight relative to the total weight of the hollow glass beads.

[0017] The present invention makes it possible to meet the need expressed above: in addition to good direct adhesion between the distinct TPE materials, it also provides articles with a desired low density.

[0018] The present invention also provides a method for direct adhesion of a first polymeric material comprising at least one PEBA to a second polymeric material comprising at least one TPU and hollow glass beads, the method being characterized in that the assembly is carried out by a method comprising heating the first polymeric material, and this melted or softened material under heating is brought into contact with at least a portion of the second polymeric material to adhere the two materials.

[0019] Surprisingly, it was discovered that the presence of the hollow glass beads allows for the provision of articles with reduced density without influencing the adhesion between the first and second polymer materials. More precisely, despite the presence of the hollow glass beads close to the interface of the two polymer materials, the adhesion between these two materials is maintained or even improved.

[0020] For the purposes of the present invention, the term "maintained adhesion" or "similar adhesion" means a ratio between the adhesion of the materials in the presence of the hollow glass beads and the adhesion of the same materials without the hollow glass beads being greater than 75%.

[0021] The invention also relates to the use of an article as defined above for the manufacture of sports equipment, a shoe element, personal protective equipment, automobile parts, construction parts, optical equipment parts, electrical and electronic equipment parts (for example, AR / VR headsets, smartphone parts, computer hardware), medical equipment parts such as catheters, transmission or transport belts.

[0022] Detailed description

[0023] The invention is now described in more detail and in a non-limiting manner in the following description. Article

[0024] The invention relates firstly to an article comprising a first polymer material and a second polymer material, the first polymer material adhering directly to the second polymer material. By "adhering directly" or "direct adhesion" is meant adhesion without the addition of a binder, in particular without the addition of glue or adhesive. Preferably, this article is obtained by the direct adhesion method described below.

[0025] First polymer material

[0026] The first polymer material according to the invention comprises at least one copolymer with PA polyamide blocks and PE polyether blocks (PEBA).

[0027] PEBA copolymers result from the polycondensation of polyamide blocks with reactive ends with polyether blocks with reactive ends, such as:

[0028] 1) polyamide blocks with diamine chain ends with polyoxyalkylene blocks with dicarboxylic chain ends;

[0029] 2) polyamide blocks with dicarboxylic chain ends with polyoxyalkylene blocks with diamine chain ends (called polyetheramine), obtained by cyanoethylation and hydrogenation of aliphatic alpha-omega dihydroxylated polyoxyalkylene blocks (called polyetherdiols);

[0030] 3) polyamide blocks with dicarboxylic chain ends with polyetherdiols, the products obtained being, in this particular case, polyetheresteramides.

[0031] Polyamide blocks with diamine chain ends originate, for example, from the condensation of polyamide precursors in the presence of a chain-limiting diamine. Polyamide blocks with dicarboxylic chain ends originate, for example, from the condensation of polyamide precursors in the presence of a chain-limiting dicarboxylic acid.

[0032] Three types of polyamide blocks can be used advantageously.

[0033] According to a first type, the polyamide blocks originate from the condensation of a dicarboxylic acid, in particular those having from 4 to 36 carbon atoms, preferably those having from 6 to 18 carbon atoms and an aliphatic or aromatic diamine, in particular those having from 2 to 20 carbon atoms, preferably those having from 4 to 14 carbon atoms. Examples of dicarboxylic acids include 1,4-cyclohexyldicarboxylic acid, butanedioic, adipic, azelaic, suberic, sebacic, dodecanedicarboxylic, octadecanedicarboxylic acids and terephthalic and isophthalic acids, but also dimerized fatty acids.These dimerized fatty acids preferably have a dimer content of at least 98%; preferably they are hydrogenated; these are, for example, the products marketed under the brand name "PRIPOL" by the company "CRODA", or under the brand name EMPOL by the company BASF, or under the brand name Radiacid by the company OLEON, and polyoxyalkylene a,oo-diacids.

[0034] Examples of diamines include tetramethylenediamine, hexamethylenediamine, 1,10-decamethylenediamine, dodecamethylenediamine, trimethylhexamethylenediamine, isomers of bis-(4-aminocyclohexyl)-methane (BACM), bis-(3-methyl-4-aminocyclohexyl)methane (BMACM), and 2-2-bis-(3-methyl-4-aminocyclohexyl)-propane (BMACP), and para-amino-di-cyclohexyl-methane (PACM), and isophoronediamine (IPDA), 2,6-bis-(aminomethyl)-norbornane (BAMN) and piperazine (Pip).

[0035] For example, we have blocks PA 412, PA 414, PA 418, PA 610, PA 612, PA 614, PA 618, PA 912, PA 1010, PA 1012, PA 1014 and PA 1018. In the PA XY notation, X represents the number of carbon atoms from the diamine residues, and Y represents the number of carbon atoms from the diacid residues, conventionally.

[0036] According to a second type, the polyamide blocks result from the condensation of one or more alpha, omega-aminocarboxylic acids and / or one or more lactams having from 6 to 12 carbon atoms in the presence of a dicarboxylic acid having from 4 to 36 carbon atoms or a diamine. Examples of lactams include caprolactam, oenantholactam and lauryllactam. Examples of alpha, omega-aminocarboxylic acids include aminocaproic, amino-7-heptanoic, amino-11-undecanoic and amino-12-dodecanoic acids.

[0037] Advantageously, the polyamide blocks of the second type are made of PA 11, PA 12 or PA 6.

[0038] According to a third type, polyamide blocks result from the condensation of at least one alpha, omega-aminocarboxylic acid (or lactam), at least one diamine and at least one dicarboxylic acid. In the PA X notation, X represents the number of carbon atoms from the amino acid residues.

[0039] In this case, the polyamide PA blocks are prepared by polycondensation:

[0040] - diamine(s) having X carbon atoms;

[0041] - dicarboxylic acid(s) having Y carbon atoms; and

[0042] - of the comonomer(s) {Z}, chosen from lactams and alpha, omega-aminocarboxylic acids having Z carbon atoms and equimolar mixtures of at least one diamine having X1 carbon atoms and at least one dicarboxylic acid having Y1 carbon atoms, (X1, Y1) being different from (X, Y);

[0043] - said comonomer(s) {Z} being introduced in a weight proportion of up to 50%, preferably up to 20%, even more advantageously up to 10% relative to all of the polyamide precursor monomers;

[0044] - in the presence of a chain limiter chosen from dicarboxylic acids. Advantageously, the dicarboxylic acid having Y carbon atoms is used as chain limiter, which is introduced in excess relative to the stoichiometry of the diamine(s).

[0045] According to a variant of this third type, the polyamide blocks result from the condensation of at least two alpha, omega-aminocarboxylic acids or at least two lactams having from 6 to 12 carbon atoms or a lactam and an aminocarboxylic acid not having the same number of carbon atoms in the possible presence of a chain limiter. The alpha, omega-amino carboxylic acids, lactams, diamines, and dicarboxylic acids may be the aforementioned types.

[0046] Examples of polyamide blocks of the third type include the following: 66 / 6, 66 / 610 / 11 / 12.

[0047] Preferably, the polymer comprises from 1 to 80% by mass of polyether blocks and from 20 to 99% by mass of polyamide blocks, preferably from 4 to 80% by mass of polyether blocks and 20 to 96% by mass of polyamide blocks.

[0048] Polyether blocks are made up of alkylene oxide units. The blocks can notably come from PEG (polyethylene glycol) blocks, i.e. those made up of ethylene oxide units, PPG (propylene glycol) blocks, i.e. those made up of propylene oxide units, PO3G (polytrimethylene glycol) blocks, i.e. those made up of polytrimethylene ether glycol units, and / or PTMG (polytetramethylene glycol) blocks, i.e. those made up of tetramethylene glycol units, also called polytetrahydrofuran. PEBA copolymers can include several types of polyethers in their chain, the copolyethers being able to be block or random.

[0049] Blocks obtained by oxyethylation of bisphenols, such as bisphenol A, can also be used. These latter products are described in patent EP 613919.

[0050] Polyether blocks can also be made up of ethoxylated primary amines. Examples of ethoxylated primary amines include products of the formula: in which m and n are between 1 and 20 and x between 8 and 18. These products are commercially available under the Noramox® brand from Arkema and under the Genamin® brand from Clariant.

[0051] Polyether blocks may include polyoxyalkylene blocks with OH diol chain ends (called polyetherdiols).

[0052] The polyether blocks may comprise polyoxyalkylene blocks with NH2 diamine chain ends, such blocks being obtainable by cyanoacetylation of aliphatic alpha-omega dihydroxylated polyoxyalkylene blocks. More particularly, the commercial products Jeffamines or Elastamine may be used (for example Jeffamine® D400, D2000, ED 2003, XTJ 542, commercial products from Huntsman).

[0053] According to one embodiment, the polyether blocks in the copolymer are polyetherdiols.

[0054] The general method for the two-step preparation of PEBA copolymers having ester bonds between the PA blocks and the PE blocks is known and is described, for example, in French patent FR2846332. The general method for preparing the PEBA copolymers of the invention having amide bonds between the PA blocks and the PE blocks is known and described, for example, in European patent EP1482011. The polyether blocks can also be mixed with polyamide precursors and a diacid chain limiter to make the polymers with polyamide blocks and polyether blocks having statistically distributed units (one-step process).

[0055] Of course, the designation PEBA in the present description of the invention relates to Pebax® marketed by Arkema, Vestamid® marketed by Evonik®, Grilamid® marketed by EMS, as well as Kellaflex® marketed by DSM or any other PEBA from other suppliers.

[0056] Advantageously, the PA blocks of the PEBA copolymer may be chosen from PA 6, 11, 12, 612, 66 / 6, 1010, 614, and / or their copolymer, preferably PA 11, 12 and / or their copolymer; and / or the PE blocks of the PEBA copolymer are PTMG blocks.

[0057] Advantageously, said PEBA used in the composition according to the invention is obtained at least partially from bio-resourced raw materials. By raw materials of renewable origin or bio-resourced raw materials is meant materials which comprise bio-resourced carbon or carbon of renewable origin. Indeed, unlike materials derived from fossil materials, materials composed of renewable raw materials contain 14 C. The “renewable carbon content” or “bio-based carbon content” is determined in accordance with ASTM D 6866 (ASTM D 6866-06) and ASTM D 7026 (ASTM D 7026-04). For example, polyamide 11-based PEBAs come at least in part from bio-based raw materials and have a bio-based carbon content of at least 1%, which corresponds to an isotopic ratio of 12 C / 14 C of at least 1.2 x 10' 14. Preferably, the PEBAs according to the invention comprise at least 50% by mass of bio-resourced carbon on the total mass of carbon, which corresponds to an isotopic ratio 12 C / 14 C of at least 0.6.10' 12 This content is advantageously higher, notably up to 100%, which corresponds to an isotopic ratio 12 C / 14 C of 1.2 x 10 -12 , for example in the case of PEBA with PA 11 blocks and PE blocks comprising PO3G, PTMG and / or PPG from raw materials of renewable origin.

[0058] The first polymeric material may comprise a PEBA content of 70 to 97%, and preferably 80 to 96% by weight relative to the weight of the first polymeric material. For example, this content may be 70 to 75%, or 75 to 80%; or 80 to 85%; or 85 to 90%; or 90 to 95%; or 95 to 97% by weight relative to the weight of the first polymeric material. According to one embodiment, the first polymeric material consists of PEBA.

[0059] Advantageously, the PEBA copolymer has an instantaneous Shore D hardness greater than or equal to 30, preferably greater than or equal to 35 and less than or equal to 80 Shore D, preferably less than or equal to 75 Shore D.

[0060] Instantaneous hardness measurements can be performed according to ISO 868:2003.

[0061] According to certain embodiments, the first polymer material may comprise one or more additional polymers. These additional polymer(s) may be chosen from polyamides, these polyamides preferably being like those described for the types of polyamide blocks above.

[0062] In some embodiments, the first polymer material is free of hollow glass beads.

[0063] Alternatively, the first polymer material comprises hollow glass beads.

[0064] According to one embodiment, the first polymeric material may comprise a hollow glass bead content of 3 to 25%, and preferably 4 to 20% by weight relative to the weight of the first polymeric material. For example, this content may be 3 to 5%, or 5 to 10%; or 10 to 15%; or 15 to 20%; or 20 to 25% by weight relative to the weight of the first polymeric material.

[0065] A hollow glass bead is a glass material that has a hollow (as opposed to solid) structure.

[0066] The hollow glass beads may have a compressive strength, measured according to ASTM D 3102-72 (1982) in glycerol, of at least 50 MPa and particularly preferably at least 100 MPa.

[0067] Hollow glass microspheres typically have an aspect ratio (L / D ratio where L represents the largest dimension of the cross-section of the bead and D the smallest dimension of the cross-section of said bead) of from 0.85 to 1, in particular from 0.90 to 1, preferably equal to 1. L and D can be measured by scanning electron microscopy (SEM).

[0068] Hollow glass beads are typically spherical or nearly spherical.

[0069] Advantageously, the hollow glass beads may have a volumetric mean diameter D50 of 10 to 80 pm, preferably 13 to 50 pm, measured by means of laser diffraction in accordance with ASTM B 822-17.

[0070] The hollow glass beads may be surface-treated with, for example, silanes (especially aminosilanes and epoxysilanes), polyamides, especially water-soluble polyamides, fatty acids, waxes, titanates, urethanes, polyhydroxyethers, epoxides, nickel, or mixtures thereof. The hollow glass beads are preferably surface-treated with aminosilanes, epoxysilanes, polyamides, or mixtures thereof.

[0071] Hollow glass beads can be formed from borosilicate glass, preferably from sodium carbonate-calcium oxide-borosilicate glass.

[0072] The hollow glass beads may preferably have an actual density of 0.10 to 0.80 g / cm 3 , preferably from 0.30 to 0.77 g / cm 3 , particularly preferably from 0.40 to 0.67 g / cm 3 , measured according to ASTM D 2840-69 (1976) using a gas pycnometer and helium as the measuring gas.

[0073] According to preferred embodiments, the hollow glass beads may comprise zinc oxide at a content greater than or equal to 1.0% by weight relative to the total weight of the hollow glass beads, and preferably greater than or equal to 2.0% by weight relative to the total weight of the hollow glass beads.

[0074] The hollow glass beads suitable for the invention may be Glass Bubbles® beads marketed by 3M, Winlight® marketed by AXYZ Chemical Co., Ltd, Sphericel® marketed by Potters and SiLiBeads® marketed by Sigmund-Linder.

[0075] The first polymer material may also include one or more additives.

[0076] The first polymeric material may comprise an additive content of 0 to 5%, and preferably 0.1 to 4% by weight relative to the weight of the first polymeric material. For example, this content may be 0 to 0.5%, or 0.5 to 1%; or 1 to 1.5%; or 1.5 to 2%; or 2 to 2.5%; or 2.5 to 3%; or 3 to 3.5%; or 3.5 to 4%; or 4 to 4.5%; or 4.5 to 5%; by weight relative to the weight of the first polymeric material.

[0077] The additive may be selected from fillers, colorants, stabilizers, plasticizers, surfactants, nucleating agents, pigments, brighteners, antioxidants, lubricants, flame retardants, natural waxes, impact modifiers, laser marking additives, and mixtures thereof.

[0078] For example, the stabilizer may be a UV stabilizer, an organic stabilizer or more generally a combination of organic stabilizers, such as a phenol-type antioxidant (for example of the type of Irganox 245 or 1098 or 1010 from the company Ciba-BASF), a phosphite-type antioxidant (for example Irgafos® 126 from the company Ciba-BASF) and possibly other stabilizers such as a HALS, which stands for Hindered Amine Light Stabilizer or hindered amine light stabilizer (for example Tinuvin 770 from the company Ciba-BASF), a UV stabilizer (for example Tinuvin 312 from the company Ciba), a phosphorus-based stabilizer. It is also possible to use amine-type antioxidants such as Naugard 445 from Crompton or polyfunctional stabilizers such as Nylostab S-EED from Clariant.

[0079] This stabilizer may also be a mineral stabilizer, such as a copper-based stabilizer. Examples of such mineral stabilizers include copper halides and acetates. Alternatively, other metals such as silver may be considered, but these are known to be less effective. These copper-based compounds are typically combined with alkali metal halides, particularly potassium.

[0080] For example, the plasticizers are selected from benzene sulfonamide derivatives, such as n-butyl benzene sulfonamide (BBSA); ethyl toluene sulfonamide or N-cyclohexyl toluene sulfonamide; hydroxybenzoic acid esters, such as ethyl-2-hexyl parahydroxybenzoate and decyl-2-hexyl parahydroxybenzoate; tetrahydrofurfuryl alcohol esters or ethers, such as oligoethyleneoxytetrahydrofurfuryl alcohol; and citric acid or hydroxymalonic acid esters, such as oligoethyleneoxy malonate.

[0081] For example, the fillers may be chosen from silica, graphite, expanded graphite, carbon black, kaolin, magnesia, slag, talc, wollastonite, mica, nanofillers (carbon nanotubes), pigments, metal oxides (titanium oxide), metals, advantageously wollastonite and talc, preferably talc.

[0082] For example, impact modifiers are polyolefins with a modulus < 200 MPa, in particular < 100 MPa, as measured according to ISO 178:2010, at 23°C.

[0083] In one embodiment, the impact modifier is chosen from a polyolefin having a modulus < 200 MPa, in particular < 100 MPa, functionalized or not, and their mixtures.

[0084] Advantageously, the functionalized polyolefin carries a function chosen from maleic anhydride, carboxylic acid, carboxylic anhydride and epoxide functions, and is in particular chosen from ethylene / octene copolymers, ethylene / butene copolymers, ethylene / propylene elastomers (EPR), ethylene-propylene-diene copolymers with elastomeric character (EPDM) and ethylene / alkyl (meth)acrylate copolymers.

[0085] For example, additives for laser marking are: Iriotec® 8835 / Iriotec® 8850 from MERCK and Laser Mark® 1001074-E / Laser Mark® 1001088-E from Ampacet Corporation.

[0086] The first polymer material may be in the form of a layer in the article according to the invention.

[0087] Second polymer material

[0088] The second polymer material according to the invention comprises at least one thermoplastic polyurethane (TPU). The thermoplastic polyurethane may be chosen from a urethane block copolyether and a urethane block copolyester.

[0089] The thermoplastic polyurethane (TPU) according to the invention is a copolymer with rigid blocks and soft blocks. TPUs result from the reaction of at least one polyisocyanate with at least one compound reactive with isocyanate, preferably having two functional groups reactive with isocyanate, more preferably a polyol, and optionally with a chain extender, optionally in the presence of a catalyst.

[0090] The rigid blocks of TPU are blocks consisting of units derived from polyisocyanates and chain extenders, while the flexible blocks mainly comprise units derived from compounds reactive with isocyanate, having a molar mass between 0.5 and 100 kg / mol, preferably polyols. The polyisocyanate can be aliphatic, cycloaliphatic, araliphatic and / or aromatic. Preferably, the polyisocyanate is a diisocyanate. Advantageously, the polyisocyanate is selected from the group consisting of tri-, tetra-, penta-, hexa-, hepta- and / or octamethylene diisocyanate, 2-methyl-pentamethylene 1,5-diisocyanate, 2-ethyl-butylene-1,4-diisocyanate, 1,5-pentamethylene diisocyanate, 1,4-butylene diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (isophorone diisocyanate, IPDI), 1,4-bis(isocyanatomethyl)cyclohexane, 1,3-bis(isocyanatomethyl)cyclohexane (HXDI), 2,4-paraphenylene diisocyanate (PPDI),2,4-tetramethylene xylene diisocyanate (TMXDI), 4,4'-, 2,4'- and / or 2,2'-dicyclohexylmethane diisocyanate (H12 MDI), 1,4-cyclohexane diisocyanate, 1-methyl-2,4- and / or 1-methyl-2,6-cyclohexane diisocyanate, 2,2'-, 2,4'- and / or 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), 2,4- and / or 2,6-toluene diisocyanate (TDI), diphenylmethane diisocyanate, 3,3'-dimethyl-diphenyl diisocyanate, 1,2-diphenylethane diisocyanate, phenylene diisocyanate, methylene bis(4-cyclohexyl isocyanate) (HMDI) and mixtures thereof.,

[0091] More preferably, the polyisocyanate is selected from the group consisting of diphenylmethane diisocyanates (MDI), toluene diisocyanates (TDI), pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), methylene bis (4-cyclohexyl isocyanate) (HMDI) and mixtures thereof.

[0092] Even more preferably, the polyisocyanate is 4,4'-MDI (4,4'-diphenylmethane diisocyanate), 1,6-HDI (1,6-hexamethylene diisocyanate) or a mixture thereof.

[0093] The isocyanate-reactive compound(s) preferably have an average functionality between 1.8 and 3, more preferably between 1.8 and 2.6, more preferably between 1.8 and 2.2. The average functionality of the isocyanate-reactive compound(s) corresponds to the number of isocyanate-reactive functions of the molecules, calculated theoretically for a molecule from a quantity of compounds. Preferably, the isocyanate-reactive compound has, according to a statistical average, a Zerewitinoff active hydrogen number in the above ranges.

[0094] Preferably, the isocyanate-reactive compound (preferably a polyol) has a number-average molar mass of 500 to 100,000 g / mol. The isocyanate-reactive compound may have a number-average molar mass of 500 to 8,000 g / mol, more preferably 700 to 6,000 g / mol, more preferably 800 to 4,000 g / mol. In embodiments, the isocyanate-reactive compound has a number average molar mass of 500 to 600 g / mol, or 600 to 700 g / mol, or 700 to 800 g / mol, or 800 to 1000 g / mol, or 1000 to 1500 g / mol, or 1500 to 2000 g / mol, or 2000 to 2500 g / mol, or 2500 to 3000 g / mol, or 3000 to 3500 g / mol, or 3500 to 4000 g / mol, or 4000 to 5000 g / mol, or 5000 to 6000 g / mol, or 6000 to 7000 g / mol, or 7000 to 8000 g / mol, or from 8000 to 10000 g / mol, or from

[0095] 10000 to 15000 g / mol, or 15000 to 20000 g / mol, or 20000 to 30000 g / mol, or 30000 to 40000 g / mol, or 40000 to 50000 g / mol, or 50000 to 60000 g / mol, or 60000 to 70000 g / mol, or 70000 to 80000 g / mol, or 80000 to 100000 g / mol. The number average molar mass can be determined by GPC, preferably according to ISO 16014-1:2012.

[0096] Advantageously, the isocyanate-reactive compound has at least one reactive group selected from hydroxyl group, amine group, thiol group and carboxylic acid group. Preferably, the isocyanate-reactive compound has at least one hydroxyl reactive group, more preferably several hydroxyl groups. Thus, particularly advantageously, the isocyanate-reactive compound comprises or consists of a polyol.

[0097] Preferably, the polyol is selected from the group consisting of polyester polyols, polyether polyols, polycarbonate diols, polysiloxane diols, polyalkylene diols, and mixtures thereof. More preferably, the polyol is a polyether polyol, a polyester polyol, and / or a polycarbonate diol, such that the flexible blocks of the thermoplastic polyurethane are polyether blocks, polyester blocks, and / or polycarbonate blocks, respectively. More preferably, the flexible blocks of the thermoplastic polyurethane are polyether blocks and / or polyester blocks (the polyol being a polyether polyol and / or a polyester polyol).As polyester polyol, mention may be made of polycaprolactone polyols and / or copolyesters based on one or more carboxylic acids chosen from adipic acid, succinic acid, pentanedioic acid and / or sebacic acid and one or more alcohols chosen from 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol and / or polytetrahydrofuran. More particularly, the copolyester may be based on adipic acid and a mixture of 1,2-ethanediol and 1,4-butanediol, or the copolyester may be based on adipic acid, succinic acid, pentanedioic acid, sebacic acid or mixtures thereof, and polytetrahydrofuran (tetramethylene glycol), or the copolyester may be a mixture of these copolyesters.

[0098] As polyether polyol, polyether diols (i.e., aliphatic α,α-dihydroxylated polyoxyalkylene blocks) are preferably used. Preferably, the polyether polyol is a polyether diol based on ethylene oxide, propylene oxide, and / or butylene oxide, a block copolymer based on ethylene oxide and propylene oxide, a polyethylene glycol, a polypropylene glycol, a polybutylene glycol, a polytetrahydrofuran, a polybutane diol, or a mixture thereof.The polyether polyol is preferably a polytetrahydrofuran (soft blocks of the thermoplastic polyurethane therefore being polytetrahydrofuran blocks) and / or a polypropylene glycol (soft blocks of the thermoplastic polyurethane therefore being polypropylene glycol blocks) and / or a polyethylene glycol (soft blocks of the thermoplastic polyurethane therefore being polyethylene glycol blocks), preferably a polytetrahydrofuran having a number average molar mass of 500 to 15000 g / mol, preferably of 1000 to 3000 g / mol. The polyether polyol may be a polyetherdiol which is the reaction product of ethylene oxide and propylene oxide; the molar ratio of ethylene oxide to propylene oxide is preferably 0.01 to 100, more preferably 0.1 to 9, more preferably 0.25 to 4, more preferably 0.4 to 2.5, more preferably 0.6 to 1.5 and it is more preferably 1.

[0099] The polysiloxane diols usable in the invention preferably have a number-average molar mass of 500 to 15000 g / mol, preferably of 1000 to 3000 g / mol. The number-average molar mass can be determined by GPC, preferably according to ISO 16014-1:2012. Advantageously, the polysiloxane diol is a polysiloxane of formula (I): HO-[RO]nR-Si(R')2-[O-Si(R')2]mO-Si(R')2-R-[OR] P -OH (I) in which R is preferably a C2-C4 alkylene, R' is preferably a C1-C4 alkyl and each of n, m and p independently represents an integer preferably between 0 and 50, m being more preferably from 1 to 50, even more preferably from 2 to 50. Preferably, the polysiloxane has the following formula (II): in which Me is a methyl group, or the following formula (III):

[0100] The polyalkylene diols which can be used in the invention are preferably based on butadiene.

[0101] The polycarbonate diols that can be used in the invention are preferably aliphatic polycarbonate diols. The polycarbonate diol is preferably based on alkanediol. Preferably, it is strictly bifunctional. The preferred polycarbonate diols according to the invention are those based on butanediol, pentanediol and / or hexanediol, in particular 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methylpentane-(1,5)-diol, or mixtures thereof, more preferably based on 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, or mixtures thereof. In particular, the polycarbonate diol may be a polycarbonate diol based on butanediol and hexanediol, or based on pentanediol and hexanediol, or based on hexanediol, or may be a mixture of two or more of these polycarbonate diols.The polycarbonate diol advantageously has a number average molar mass of 500 to 4000 g / mol, preferably 650 to 3500 g / mol, more preferably 800 to 3000 g / mol. The number average molar mass can be determined by GPC, preferably according to ISO 16014-1:2012.

[0102] One or more polyols may be used as the isocyanate-reactive compound.

[0103] Particularly preferably, the flexible TPU blocks are blocks of polytetrahydrofuran, polypropylene glycol and / or polyethylene glycol.

[0104] Preferably, a chain extender is used for the preparation of the thermoplastic polyurethane, in addition to the isocyanate and the isocyanate-reactive compound.

[0105] The chain extender may be aliphatic, araliphatic, aromatic, and / or cycloaliphatic. It advantageously has a number-average molar mass of 50 to 499 g / mol. The number-average molar mass may be determined by GPC, preferably according to ISO 16014-1:2012. The chain extender preferably has two isocyanate-reactive groups (also called "functional groups"). A single chain extender or a mixture of at least two chain extenders may be used. The chain extender is preferably bifunctional. Examples of chain extenders are diamines and alkanediols having 2 to 10 carbon atoms.In particular, the chain extender may be selected from the group consisting of 1,2-ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanediol, 1,4-dimethanol cyclohexane, neopentyl glycol, hydroquinone bis(beta-hydroxyethyl)ether (HQEE), di-, tri-, tetra-, penta-, hexa-, hepta-, octa-, nona- and / or deca-alkylene glycol, their respective oligomers, polypropylene glycol and mixtures thereof. More preferably, the chain extender is chosen from the group consisting of 1,2-ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and mixtures thereof, and more preferably it is chosen from 1,3-propanediol, 1,4-butanediol and / or 1,6-hexanediol.Even more preferably, the chain extender is a mixture of 1,4-butanediol and 1,6-hexanediol, more preferably in a molar ratio of 6:1 to 10:1.

[0106] Advantageously, a catalyst is used to synthesize the thermoplastic polyurethane. The catalyst accelerates the reaction between the NCO groups of the polyisocyanate and the isocyanate-reactive compound (preferably with the hydroxyl groups of the isocyanate-reactive compound) and, if present, with the chain extender.

[0107] The catalyst is preferably a tertiary amine, more preferably selected from triethylamine, dimethylcyclohexylamine, N-methylmorpholine, N,N'-dimethylpiperazine, 2-(dimethylaminoethoxy)-ethanol and / or diazabicyclo-(2,2,2)-octane. Alternatively, or additionally, the catalyst is an organic metal compound such as a titanium acid ester, an iron compound, preferably ferric acetylacetonate, a tin compound, preferably those of carboxylic acids, more preferably tin diacetate, tin dioctoate, tin dilaurate or dialkyl tin salts, preferably dibutyltin diacetate and / or dibutyltin dilaurate, a bismuth carboxylic acid salt, preferably bismuth decanoate, or a mixture thereof. More preferably, the catalyst is selected from the group consisting of tin dioctoate, bismuth decanoate, titanium acid esters and mixtures thereof.More preferably, the catalyst is tin dioctoate.

[0108] When preparing thermoplastic polyurethane, the molar ratios of the isocyanate-reactive compound and the chain extender can be varied to adjust the hardness and melt flow rate of the TPU. Indeed, as the proportion of chain extender increases, the hardness and melt viscosity of the TPU increase while the melt flow rate of the TPU decreases. For the production of soft TPU, preferably TPU having a Shore A hardness of less than 95, more preferably 75 to 95, the isocyanate-reactive compound and the chain extender may be used in a molar ratio of 1:1 to 1:5, preferably 1:1.5 to 1:4.5, preferably such that the mixture of isocyanate-reactive compound and chain extender has a hydroxyl equivalent weight of greater than 200, more preferably 230 to 650, even more preferably 230 to 500.For the production of a harder TPU, preferably a TPU having a Shore A hardness greater than 98, preferably a Shore D hardness of 55 to 75, the isocyanate-reactive compound and the chain extender may be used in a molar ratio of 1:5.5 to 1:15, preferably 1:6 to 1:12, preferably such that the mixture of isocyanate-reactive compound and chain extender has a hydroxyl equivalent weight of 110 to 200, more preferably 120 to 180.

[0109] Advantageously, to prepare the TPU, the polyisocyanate, the isocyanate-reactive compound, and preferably the chain extender are reacted, preferably in the presence of a catalyst, in amounts such that the equivalent ratio of the NCO groups of the polyisocyanate to the sum of the hydroxyl groups of the isocyanate-reactive compound and the chain extender is from 0.95:1 to 1.10:1, preferably from 0.98:1 to 1.08:1, more preferably from 1:1 to 1.05:1. The catalyst is advantageously present in an amount of from 0.0001 to 0.1 parts by weight per 100 parts by weight of the TPU synthesis reactants.

[0110] The TPU according to the invention preferably has a weight average molar mass greater than or equal to 10,000 g / mol, preferably greater than or equal to 40,000 g / mol and more preferably greater than or equal to 60,000 g / mol. Preferably, the weight average molar mass of the TPU is less than or equal to 80,000 g / mol. The weight average molar masses can be determined by gel permeation chromatography (GPC).

[0111] Advantageously, the TPU is semi-crystalline. Its melting temperature Tf is preferably between 100°C and 230°C, more preferably between 120°C and 200°C. The melting temperature can be measured according to ISO 11357-3 Plastics - Differential scanning calorimetry (DSC) Part 3.

[0112] Advantageously, the TPU may be a recycled TPU and / or a partially or completely bio-sourced TPU. Preferably, the TPU has a Shore D hardness of less than or equal to 75 D, more preferably less than or equal to 65 D. In particular, the TPU used in the invention may have a hardness of 65 Shore A to 70 Shore D, preferably of 75 Shore A to 60 Shore D. The hardness measurements may be carried out according to the ISO 7619-1 standard.

[0113] The second polymer material may comprise a single TPU (as described above) or several such TPUs in a blend.

[0114] The second polymeric material may comprise a TPU content of 70 to 97%, and preferably 80 to 96% by weight relative to the weight of the second polymeric material. For example, this content may be 70 to 75%, or 75 to 80%; or 80 to 85%; or 85 to 90%; or 90 to 95%; or 95 to 97% by weight relative to the weight of the second polymeric material.

[0115] According to some embodiments, the second polymer material may further comprise at least one thermoplastic elastomeric polymer (TPE) other than thermoplastic polyurethane (TPU). This TPE may be selected from a PEBA (as described above), a copolyether block ester (CoPE) and combinations thereof.

[0116] CoPE comprises at least one polyether (PE) block, and at least one PES polyester block (homopolymer or copolyester).

[0117] The polyester block may be obtained by polycondensation by esterification of a carboxylic acid, such as isophthalic acid or terephthalic acid or a bio-sourced carboxylic acid (such as furan dicarboxylic acid), with a glycol, such as ethylene glycol, trimethylene glycol, propylene glycol or tetramethylene glycol. The polyether blocks may be as described above in the description of PEBAs.

[0118] The second polymer material comprises hollow glass beads.

[0119] Thus, the hollow glass beads can be present either only in the second polymer material or in both the first and second polymer materials.

[0120] The hollow glass beads are as described above.

[0121] The second polymeric material may comprise a hollow glass bead content of 3 to 25%, and preferably 4 to 20% by weight relative to the weight of the second polymeric material. For example, this content may be 3 to 5%, or 5 to 10%; or 10 to 15%; or 15 to 20%; or 20 to 25% by weight relative to the weight of the second polymeric material.

[0122] According to preferred embodiments, the hollow glass beads may comprise zinc oxide at a content greater than or equal to 1.0% by weight relative to the total weight of the hollow glass beads, and preferably greater than or equal to 2.0% by weight relative to the total weight of the hollow glass beads.

[0123] The second polymer material may also comprise one or more additives. These additives are as described above in connection with the first material.

[0124] The second polymeric material may comprise an additive content of 0 to 5%, and preferably of 0.1 to 4% by weight relative to the weight of the second polymeric material. For example, this content may be 0 to 0.5%, or 0.5 to 1%; or 1 to 1.5%; or 1.5 to 2%; or 2 to 2.5%; or 2.5 to 3%; or 3 to 3.5%; or 3.5 to 4%; or 4 to 4.5%; or 4.5 to 5%; by weight relative to the weight of the second polymeric material.

[0125] The second polymer material may be in the form of a layer in the article according to the invention.

[0126] The article according to the invention may also comprise one or more layers of additional materials.

[0127] According to one embodiment, the article of the invention comprises:

[0128] 60-95% by weight of the first polymeric material and the second polymeric material;

[0129] 3-25% by weight of hollow glass beads;

[0130] 0-10% by weight of one or more additives; the total making 100% by weight of the article.

[0131] Adhesion process

[0132] The present invention also relates to a method for direct adhesion of a first polymer material as described above to a second polymer material as described above.

[0133] In one embodiment, the first polymer material is melted or softened under heating, and the molten material is brought into contact with at least a portion of the second polymer material to adhere the two materials. In another embodiment, the first polymer material and the second polymer material are independently melted or softened under heating, and the molten first polymer material is brought into contact with at least a portion of the molten second polymer material to adhere the two materials.

[0134] Advantageously, in the assembly method according to the invention, the first polymer material and the second polymer material are assembled by a direct adhesion method chosen from: overmolding, hot pressing, coextrusion, thermoforming, injection molding, extrusion molding, blow molding, and mixtures thereof; preferably by overmolding.

[0135] According to one embodiment, the method is a method of overmolding the first polymer material, containing or not hollow glass beads, onto the second polymer material containing hollow glass beads.

[0136] According to one embodiment, the hollow glass beads comprise zinc oxide at a content greater than or equal to 1.0% by weight relative to the total weight of the hollow glass beads, and preferably greater than or equal to 2.0% by weight relative to the total weight of the hollow glass beads.

[0137] Advantageously, the assembly temperature of the direct adhesion process according to the invention is between 220 and 300°C, preferably between 240 and 290°C, preferably between 250 and 290°C.

[0138] Such a method can for example be carried out by joining the first and second polymer materials in a molding process, by injection, in particular two-material injection, two-color injection, multi-color, bi-injection, co-injection. Other conventional methods can be used: thermoforming, hot press molding, insert molding, sandwich injection molding, extrusion molding, in particular by coextrusion, injection-blow molding, and other methods for implementing TPE materials. The person skilled in the art chooses the type of injection press according to the type of mold, insert and materials to be injected.

[0139] According to a particular embodiment of hot press molding, the first and second polymer materials in the form of granules, powder or any other form are loaded into a metal mold. According to another embodiment, the first and second polymer materials, in the form of pre-molded articles, are loaded into a metal mold. According to yet another embodiment of insert injection molding, a molded composite article can be produced by: molding the second polymer material using a method such as injection molding, extrusion molding, in particular of sheet, or film; then inserting or shaping the article thus molded into a metal mold; then injecting the first polymer material not yet molded into a space or cavity between the molded article and the metal mold.In insert injection molding, the molded article to be inserted into the metal mold is preferably preheated in the metal mold.

[0140] The following examples illustrate the invention without limiting it.

[0141] Materials used:

[0142] - PEBA 1: a copolymer with PA11 blocks and PTMG blocks with instant hardness 53 Shore D.

[0143] - TPU 1: commercial product Elastollan® 1195A (BASF) - a urethane block copolyether, 95 Shore A.

[0144] - TPU 2: commercial product Pearlthane® ECO 12T95 (Lubrizol) - a urethane block copolyester, 95 Shore A.

[0145] - R1: hollow glass beads, density 0.60 g / cc, D50 = 30 pm, ZnO content is approximately 3%, compressive strength is 125 mPA.

[0146] In the context of the present invention, the adhesion between two polymer materials is expressed by the peel force in kgf / cm, measured according to the ISO11339 standard.

[0147] Example 1

[0148] Different second polymer materials (DMP) were prepared as shown in Table 1. The DMP compositions in Table 1 were prepared by melt blending TPU granules with hollow glass beads and stabilizing additives (antioxidants). This blending was carried out by compounding on a 26 mm diameter co-rotating twin-screw extruder with a flat temperature profile (T°) at 185°C. The screw speed was 250 rpm and the flow rate was 15 kg / h. The TPU(s) and additives were introduced into the main hopper. The hollow glass beads were introduced by side feed. The compositions were then molded on an injection molding machine (Toshiba) at a set temperature of 220°C and a mold temperature of 20°C in the form of 2 mm thick plates. The insert plates thus prepared were then placed in a 4 mm thick mold for overmolding.

[0149] Table 1]

[0150] The PEBA1 was then overmolded onto the inserts of the various DMPs 1 to 6 at an assembly temperature of 260°C and a mold temperature of 60°C.

[0151] The overmolded articles thus prepared were then cut into 20 mm wide strips, on which peel tests were carried out according to ISO11339 standard with a separation speed of 100 mm / min. The results of these tests are given in Table 2 below.

[0152] The following table compares the adhesion (peel force in kgf / cm) of PEBA 1 (first polymer material) to DMP 1 to 6 inserts (second polymer materials), after direct adhesion by overmolding.

[0153] It is found that the first polymer material PEBA 1 has a similar or even improved adhesion to the second polymer materials (DMP2, DMP3, DMP5 and DMP6) compared to the second polymer materials without hollow glass beads (DMP1 and DMP4). The density of the overmolded articles was measured according to ISO 1183-3:1999 (Table 3).

[0154] Table 3]

[0155] It is observed that the density of overmolded articles comprising hollow glass beads is reduced compared to overmolded articles not comprising hollow glass beads (DMP1-PEBA1 and DMP4-PEBA1).

[0156] Example 2

[0157] In this example, peel tests were carried out using the second polymer materials DMP1 and DMP3 (as described in Example 1) as inserts, onto which the first polymer materials PMP1, PMP2 or PMP3 are overmolded. The compositions PMP1 to PMP3 in Table 4 were prepared by melt mixing the PEBA granules with the hollow glass beads and the stabilizing additives (antioxidants). This mixing was carried out by compounding on a co-rotating twin-screw extruder with a diameter of 26 mm with a flat temperature profile (T°) at 250°C. The screw speed is 250 rpm and the flow rate is 20 kg / h. The PEBA(s) and the additives are introduced into the main hopper. The hollow glass beads are introduced by side force-feeding.

[0158] The compositions were then overmolded at a set temperature of 260°C and a mold temperature of 60°C in the form of 2 mm thick plates on the inserts of the different DMP1 and DMP3 materials.

[0159] The overmolded articles thus prepared were then cut into 20 mm wide strips, on which peel tests were carried out according to ISO11339 standard with a separation speed of 100 mm / min.

[0160] Table 4]

[0161] Table 5 compares the adhesion (peel force in kgf / cm) of PMP1 and PMP3 on DMP1 and 3 inserts, after direct adhesion by overmolding.

[0162] The density of the overmolded articles was measured according to ISO 1183-3:1999 (Table 6).

[0163] It is observed that the density of overmolded articles comprising hollow glass beads is reduced compared to overmolded articles not comprising hollow glass beads (DMP1-PMP1).

[0164] It is noted that even in the case where the hollow glass beads are present in the first and second polymer materials, the invention makes it possible to obtain articles of lower density and with adhesion between the materials which are similar, or even improved, compared to the polymer materials (first or second) without the hollow glass beads.

[0165] Example 3 (Counterexample)

[0166] In this example, a peel test was carried out using the first polymer material PMP1 as described in Example 2 as an insert, onto which the second polymer material DMP3 as described in Example 1 is overmolded. The composition was then overmolded at a set temperature of 230°C and a mold temperature of 60°C in the form of 2 mm thick plates onto the insert PMP1.

[0167] The overmolded article thus prepared was then cut into 20 mm wide strips, on which peel tests were carried out according to ISO11339 standard with a separation speed of 100 mm / min.

[0168] The adhesion (peel force in kgf / cm) of DPM3 overmolded on the PMP1 insert was measured at 4 kgf / cm, which is significantly lower than the peel force measured on the adhesion of PMP1 overmolded on the DPM3 insert (>20, Table 2).

Claims

Demands 1. Article comprising a first polymer material comprising at least one polyamide and polyether block copolymer (PEBA) and a second polymer material comprising at least one thermoplastic polyurethane (TPU), the first polymer material adhering directly to the second polymer material, and the second polymer material comprising hollow glass beads.

2. Article according to claim 1, wherein the adhesion between two polymer materials, expressed by the peel force in kgf / cm, is greater than or equal to 10 kgf / cm, preferably greater than or equal to 12 kgf / cm.

3. Article according to any one of the preceding claims, wherein the PEBA copolymer has an instantaneous Shore D hardness greater than or equal to 30, preferably greater than or equal to 35 and less than or equal to 80 Shore D, preferably less than or equal to 75 Shore D.

4. Article according to any one of the preceding claims, wherein the PA blocks of the PEBA copolymer are selected from PA 6, 11, 12, 612, 66 / 6, 1010, 614, and / or their copolymer, preferably PA 11, 12 and / or their copolymer; and / or the PE blocks of the PEBA copolymer are PTMG blocks.

5. Article according to any one of the preceding claims, wherein the hollow glass beads have a content of 3 to 25% by weight relative to the total weight of the second polymer material.

6. Article according to any one of the preceding claims, wherein the first polymer material comprises a content of hollow glass beads of 3 to 25% by weight relative to the weight of the first polymer material.

7. Article according to any one of claims 1 to 6, wherein the hollow glass beads comprise zinc oxide having a content greater than or equal to 1.0% by weight relative to the total weight of the hollow glass beads, and preferably greater than or equal to 2.0% by weight relative to the total weight of the hollow glass beads.

8. Article according to one of the preceding claims, comprising: 60-95% by weight of the first polymer material and the second polymer material; 3-25% by weight of hollow glass beads; 0-10% of one or more additives; the total making 100% by weight of the article.

9. Use of an article according to any of the preceding claims for the manufacture of sports equipment, a shoe component, personal protective equipment, automotive parts, construction parts, optical equipment parts, electrical and electronic equipment parts, medical equipment parts such as catheters, transmission or conveyor belts.

10. A method for the direct adhesion of a first polymer material comprising at least one copolymer of polyamide blocks and polyether blocks to a second polymer material comprising at least one thermoplastic polyurethane and hollow glass beads, the method being characterized in that the assembly is carried out by a process comprising heating the first polymer material, and this molten or softened material under heating is brought into contact with at least a part of the second polymer material to make the two materials adhere.

11. A method according to claim 10, wherein the first polymer material and the second polymer material are joined by a direct bonding method selected from: overmolding, hot pressing, co-extrusion, thermoforming, injection molding, extrusion molding, blow molding, and mixtures thereof; preferably by overmolding one material onto the other.

12. A method according to any one of claims 10 to 11, being a method of overmolding the first polymer material onto the second polymer material containing hollow glass beads.

13. A method according to any one of claims 10 to 12, wherein the hollow glass beads comprise zinc oxide having a content greater than or equal to 1.0% by weight relative to the total weight of the hollow glass beads, and preferably greater than or equal to 2.0% by weight relative to the total weight of the hollow glass beads.

14. A method according to any one of claims 10 to 13, wherein the assembly temperature is in the range of 220 to 300°C, preferably 240 to 290°C, preferably 250 to 290°C.

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