FR3137387A1 - Elastomer composite comprising crosslinked rubber particles - Google Patents

Abstract

The invention mainly aims at a two-layer composite comprising a layer A and a layer B, in which the layer A comprises at least 30% by weight relative to the weight of the layer A of at least one thermoplastic polymer; and layer B comprises at least 25% by weight based on the weight of layer B of at least one thermoplastic polymer and 1 to 75% by weight based on the total weight of layer B of crosslinked rubber particles. It also covers a process for its manufacture as well as its use, the objects thus obtained, a process for their recycling, the composition likely to be obtained and its use.

Description

Elastomer composite comprising crosslinked rubber particles

The present patent application relates to a composite comprising an elastomer loaded with crosslinked rubber particles, its manufacturing process as well as its use, in particular as a component of objects such as shoes or sports equipment, the objects thus obtained as well as a process for their recycling.

In the field of sports shoe manufacturing, we are particularly looking for materials combining excellent elastic return, good anti-slip behavior, low density and good abrasion resistance.

In many cases, the assembly of several complementary materials in the form of a composite makes it possible to achieve combinations of properties that are inaccessible for a single material. However, it is generally necessary for these composites to have a significant peel force (in particular > 8 preferably, >15 N/cm). For reasons of ease of manufacturing and recycling, it is preferred that the materials in the composite have sufficient affinity so that the need for an adhesive can be avoided. For this reason, we also seek to use thermoplastic materials.

The patent applicationWO 95 / 12481 describes two-layer composites comprising a lightweight elastomer of the polyetheramide type adhering in itself to a non-light thermoplastic which can be a polyetheramide, polyetherester or polyurethane. These composites are very useful in certain applications, but do not provide the slip resistance required for certain applications, notably in the area of sports shoe soles.

The patent applicationEP 1 568 487 A1discloses composite articles comprising parts based on polyamide or polyamide elastomer and based on thermoplastic polyurethane (TPU) assembled by overmolding. However, these composites have limited abrasion resistance.

Furthermore, patent application WO 2017/043987 A1 describes a composite comprising rubber and polyamide in which a reactive copolymer is introduced as a modifier in the two materials in order to improve the quality of the assembly produced without adhesive. However, these composites are not recyclable.

Patent application WO 2018/005295 A1 discloses multi-layer structures comprising, in contact with a core layer, a layer comprising an alloy of thermoplastic polyurethane and rubber. However, the time required for rubber vulcanization makes these composites expensive to produce and the resulting alloy is not recyclable.

The patent applicationCN 107696538 Aalso describes the overmolding of foamed TPU on TPU for the manufacture of shoes. However, these composites have modest abrasion resistance.

Unexpectedly, it was found that composites combining a thermoplastic polymer and a thermoplastic elastomer loaded with crosslinked rubber particles made it possible to overcome the limits of the compositions of the state of the art.

Also, according to a first aspect, the invention therefore aims to propose a two-layer composite comprising a layer A and a layer B, in which:

• layer A comprises at least 30% by weight relative to the weight of layer A of at least one thermoplastic polymer chosen from thermoplastic elastomers and polyamides; And
• the layer B comprises at least 25% by weight relative to the weight of layer B of at least one thermoplastic chosen from thermoplastic elastomers and polyamides and 1 to 75% by weight relative to the total weight of layer B of particles of crosslinked rubber.

The composites according to the invention have the advantage of combining elastic return properties with anti-slip behavior, low density and excellent abrasion resistance while being easy and quick to manufacture.

In particular, the addition of cross-linked rubber particles, for example from tire recycling, to thermoplastic elastomers makes it possible to obtain mechanical properties close to rubber while retaining a meltable and therefore recyclable material. The compositions obtained also have the advantage of being transformable more quickly than a rubber since the layer does not require vulcanization time and can be transformed using traditional automated plastics processing processes, for example extrusion. or injection.

In addition, the assembly of this layer with a thermoplastic material can advantageously be carried out without adding adhesive and without requiring sewing.

According to one embodiment, the composite can be made with a thermoplastic polymer in the form of foam, and thus gain in lightness, comfort and cushioning. These composites are particularly interesting for the manufacture of intermediate and outer soles (midsole and outsole) of sports shoes.

According to another embodiment, the composite can be made with a thermoplastic polymer loaded with reinforcements in order to increase the rigidity of the structural composite. These composites are particularly interesting for the manufacture of outer soles of street shoes.

According to one embodiment, the thermoplastic elastomer in layer A and/or B is chosen from thermoplastic polyurethanes (TPU), polyetheramides (PEBA) and copolyester elastomers (TPE-E).

According to one embodiment, the thermoplastic polymer in layer A and/or B is chosen from polyamides or thermoplastic elastomers, in particular chosen from thermoplastic polyurethanes (TPU), styrene and butadiene block copolymers (SBS) and copolymers. with styrene, ethylene and butadiene blocks (SEBS), polyester elastomers such as ether ester block copolymers (COPE) and polyamide elastomers such as polyethers with amide blocks (PEBA).

According to one embodiment, the thermoplastic polymer in layer A and the thermoplastic polymer in layer B belong to the same polymer family.

According to one embodiment, the thermoplastic polymer in layer A has a density less than 1, preferably <0.3.

According to one embodiment, the crosslinked rubber particles are obtained by grinding used tires.

According to one embodiment, layer A comprises 10 to 60% by weight of fillers relative to the weight of layer A.

According to one embodiment, the thermoplastic polymer in layer A and in layer B are chosen respectively from polyamides or thermoplastic polyurethanes (TPU) or polyetheramides (PEBA).

According to one embodiment, layer A is at least partially in direct contact with layer B.

According to a second aspect, the invention aims at a method of manufacturing such a two-layer composite, comprising a step consisting of bringing the material of layer A and/or the material of layer B to the molten state then putting the two materials in contact with each other.

According to one embodiment, the layers of the two-layer composite are assembled by overmolding, bi-injection, injection-foaming, thermocompression, extrusion, coextrusion, thermoforming, blow molding or even by low pressure injection molding.

According to one embodiment, said method does not include an assembly step using an adhesive.

According to another aspect, the invention aims at the use of such a two-layer composite as a component of shoes; parts of sports equipment such as parts for ski poles, frames for ski masks, handles for rackets and golf clubs and goalkeeper gloves; treadmills ; aquatic equipment such as diving shoes, mask parts or snorkels; spectacle frame parts, such as sleeve, temples, or plates; shock and/or vibration absorbers; cases for external batteries; automobile parts, including gaskets and end caps; toys ; watch straps; rollers; wheels; machine control keys; seals ; or as a component of transport belts.

According to yet another aspect, the invention relates to an object comprising such a two-layer composite, in particular chosen from shoes; sports equipment such as ski poles, ski masks, rackets, golf clubs, goalkeeper gloves; treadmills ; aquatic equipment such as diving shoes, masks and snorkels; spectacle frames; shock and/or vibration absorbers; cases for external batteries; automobile parts, including gaskets and end caps; toys ; watch straps; rollers; wheels; machine control keys; seals ; and conveyor belts.

According to yet another aspect, the invention aims at a process for recycling said used object, comprising the following steps:

(a) Grinding said used object to obtain a ground material;

(b) Heating the ground material until it melts to form a molten mass; And

(c) Extrusion of the molten mass obtained in step (b) in the form of granules.

According to yet another aspect, the invention relates to the composition capable of being obtained by said recycling process.

According to a final aspect, the invention aims at the use of said composition for the manufacture of objects as defined above.

The present invention makes it possible to meet the need expressed above. More particularly, it provides a two-layer composite with good abrasion resistance and good anti-slip properties as estimated using the coefficient of friction. Depending on the choice of thermoplastic polymers in the composite, it can also have good elastic return, lightness or, on the contrary, high rigidity. Furthermore, the composite has, due to the presence of thermoplastic polymer, a meltable character and is therefore easily recyclable.

Definition of terms

The term “ two-layer composite ” is understood to designate a component combining two layers of different compositions. The layers may or may not be in direct contact, particularly when they are assembled using an intermediate layer having an adhesive function.

The term “ thermoplastic polymer ” is understood to mean a polymer that softens when heated and becomes hard again when cooled. This category of polymers can be used by injection, extrusion or recycled, unlike thermosetting polymers which harden irreversibly when heated.

The term “ layer ” is understood to designate a piece of basically any shape. The two layers forming the two-layer composite of the invention can be of identical or different shape. According to one embodiment, at least one of the layers and preferably the two layers of the two-layer composite are of flat shape, that is to say have a significantly smaller dimension (for example 2 to 50 times, in particular 4 to 20 times, and in particular 5 to 10 times) compared to the average of the two other dimensions.

The term “ crosslinked rubber ” is understood to designate a crosslinked elastomer, that is to say comprising bridges between the chains of the elastomer thus forming a three-dimensional network.

The term “ elastomer ” is understood to designate a polymer or a mixture of polymers whose elongation at break is greater than 200% and sufficiently resistant to impact to cause no rupture during a Charpy notched test ISO 179/1eA .

By the term “ mixture ” or “ alloy ” we mean a homogeneous composition macroscopically, that is to say to the naked eye. The term also includes such compositions composed of phases which are immiscible with each other and dispersed on a micrometric or nanometric scale.

The term “ copolymer ” is understood to designate a polymer resulting from the copolymerization of at least two types of chemically different monomers, called comonomers. A copolymer is therefore formed of at least two repeating units. It can also be formed from three or more repeating patterns. More specifically, the term “ block copolymer ” or “ block copolymer ” is intended to designate copolymers in the aforementioned sense, in which at least two distinct blocks of monomers are linked by covalent bond. The length of the blocks can be variable. Preferably, the blocks are composed of 1 to 1000, preferably 1 to 100, and in particular 1 to 50 repetition units, respectively. The bond between the two monomer blocks may sometimes require an intermediate non-repeating unit called a junction block.

The term “ monomer ” must be taken in the context of polyamides in the sense of “repeating unit”. Indeed, the case where a repeating unit of the polyamide is constituted by the association of a diacid with a diamine is particular. We consider that it is the combination of a diamine and a diacid, that is to say the diamine.diacid couple (in equimolar quantity), which corresponds to the monomer. This is explained by the fact that individually, the diacid or diamine is only a structural unit, which alone is not sufficient to polymerize.

The term “ polymer family ” is understood to designate in the context of this presentation a group of polymers obtained from monomers of similar chemical structure, in particular having common functional groups. Thus, we consider that polyamides, copolyamides and polyetheramides constitute one family of polymers, thermoplastic polyurethanes constitute another, and copolyester elastomers constitute yet another family of polymers.

The term " compatible " is understood to designate an agent promoting the affinity between two materials, in particular in the context of the present invention between the thermoplastic elastomer and the crosslinked rubber particles or between the thermoplastic polymer of the layer A and the thermoplastic elastomer of layer B. These may in particular be molecules, macromolecules, polymers or copolymers having a good affinity for the two materials, thus likely to promote their physical cohesion or to form a chemical bond between them.

The nomenclature used to designate polyamides and copolyamides in this presentation follows the ISO 1874-1:2010 standard.

In the following, unless otherwise stated, hardness is given as measured according to standard 1874-1:2010.

It is also specified that the expressions “ between… and… ” and “ from… to… ” used in this description must be understood as including each of the limits mentioned.

In its broadest definition, the invention therefore aims at a two-layer composite comprising a layer of thermoplastic elastomer loaded with crosslinked rubber particles and a layer of thermoplastic polymer.

In this composite, the crosslinked rubber is advantageously replaced by a thermoplastic elastomer loaded with crosslinked rubber particles. In fact, crosslinked rubber particles, particularly from used tires, provide similar properties but make it possible to do without the crosslinking step, which makes manufacturing faster. On the other hand, the composite mainly contains thermoplastic components, which makes it easily recyclable.

More specifically, the two-layer composite according to the invention comprises a layer A and a layer B, in which

• layer A comprises at least 30% by weight relative to the weight of layer A of at least one thermoplastic polymer chosen from thermoplastic elastomers and polyamides; And
• the layer B comprises at least 25% by weight relative to the weight of layer B of at least one thermoplastic chosen from thermoplastic elastomers and polyamides and 1 to 75% by weight relative to the total weight of layer B of particles of crosslinked rubber.

The respective components of layers A and B are explained in more detail below.

The thermoplastic polymer in layer A and B respectively can be chosen independently from polyamides or thermoplastic elastomers.

By the term “ thermoplastic elastomer ” (TPE) is meant in the context of this presentation an elastic thermoplastic material withstanding large deformations before rupture. More specifically, it may be a copolymer comprising flexible segments and rigid segments, for example in the form of a block copolymer. The flexible blocks and the rigid blocks can be linked by carbon-carbon bonds or by functions which can be chosen from amides, esters, urethanes, and ureas.

In these copolymers, the rigid segments melt or soften as the temperature increases. Above the melting temperature or the glass transition temperature of the domains of rigid segments, the material can therefore be implemented by conventional techniques for implementing thermoplastic polymers. Below the melting temperature of the rigid segment domains, the thermoplastic elastomer exhibits elastic properties close to those of crosslinked elastomers.

Alternatively, they can also be mixtures combining the presence of a flexible elastomer phase, crosslinked or not, dispersed in a rigid thermoplastic continuous phase. The mixtures may in particular be mixtures of a thermoplastic polymer with an elastomer in an appropriate quantity.

According to embodiments, the thermoplastic elastomer present in layer A and in layer B of the two-layer composite of the invention can be chosen from thermoplastic polyurethanes (TPU), copolyester elastomers (TPE-E), copolymers with styrene-butadiene blocks (SBS) and styrene-ethylene-butadiene block copolymers (SEBS), polyester elastomers such as ether ester block copolymers (COPE) and polyamide elastomers such as amide block polyethers (PEBA).

According to yet another embodiment, the thermoplastic elastomer advantageously comprises rigid blocks chosen from polyamides, polyurethanes and polyesters.

According to embodiments, the ratio between the flexible blocks and the rigid blocks is chosen so that the tensile modulus of the thermoplastic elastomer, measured according to the ISO 527 standard, is between 5 and 800 MPa, preferably between 10 and 300 MPa, and more preferably between 20 and 150 MPa.

According to embodiments, the thermoplastic elastomer has a Shore hardness of between 10D and 70D, in particular between 25D and 45D.

According to embodiments, layer A and/or B may comprise several thermoplastic elastomers, in particular chosen from thermoplastic polyurethanes (TPU), styrene and butadiene block copolymers (SBS) and styrene, ethylene and butadiene block copolymers ( SEBS), polyester elastomers such as ether ester block copolymers (COPE) and polyamide elastomers such as amide block polyethers (PEBA). In one embodiment, the different thermoplastic elastomers are linked by one or more covalent bonds. The groups which can bind the thermoplastic elastomers may in particular be chosen from urethanes, ureas, amides, and esters.

As an example of such a mixture, we can mention a TPU-PEBA alloy, the two copolymers TPU and PEBA being able to be linked by one or more covalent bonds. In embodiments, at least part of the copolymer with polyamide blocks and polyether blocks is covalently linked to at least part of the thermoplastic polyurethane by a urethane function, preferably an amount less than or equal to 10% by weight, more preferably less than or equal to 5% by weight, the copolymer with polyamide blocks and polyether blocks is covalently linked to at least part of the thermoplastic polyurethane by a urethane function.

Thermoplastic polyurethanes

The thermoplastic elastomer may in particular be a thermoplastic polyurethane (TPU).

Thermoplastic polyurethane within the meaning of this presentation is a copolymer with rigid blocks and flexible blocks.

Generally speaking, in this text, the term “ rigid block ” means a block which has a melting point or a glass transition temperature greater than 60°C. The presence of a melting point can be determined by differential scanning calorimetry, according to standard ISO 11357-3 Plastics - Differential scanning calorimetry (DSC) Part 3. By “ soft block ”, we mean a block having a transition temperature vitreous (Tg) less than or equal to 0°C. The glass transition temperature can be determined by differential scanning calorimetry, according to standard ISO 11357-2 Plastics - Differential scanning calorimetry (DSC) Part 2.

Thermoplastic polyurethanes result from the reaction of at least one polyisocyanate with at least one compound reactive with the isocyanate, preferably having two functional groups reactive with the isocyanate, more preferably a polyol, and optionally with a chain extender, optionally in the presence of a catalyst. The rigid blocks of TPU are blocks made up of units derived from polyisocyanates and chain extenders while the flexible blocks mainly comprise units derived from compounds reactive with isocyanate having a molar mass of between 0.5 and 100 kg/ mol, preferably polyols.

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

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

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

The compound(s) reactive with isocyanate 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 compound(s) reactive with isocyanate corresponds to the number of functions reactive with isocyanate of the molecules, calculated theoretically for a molecule from a quantity of compounds. Preferably, the compound reactive with the isocyanate has, on a statistical average, a Zerewitinoff active hydrogen number in the above ranges.

Preferably, the compound reactive with the isocyanate (preferably a polyol) has a number average molar mass of 500 to 100,000 g/mol. The compound reactive with the isocyanate may have a number average molar mass of 500 to 8000 g/mol, more preferably 700 to 6000 g/mol, more particularly 800 to 4000 g/mol. The number average molar mass can be determined by GPC, preferably according to ISO 16014-1:2012.

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

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

As polyether polyols, polyetherdiols (i.e. aliphatic polyoxyalkylene α,ω-dihydroxylated blocks) are preferably used. Preferably, the polyether polyol is a polyetherdiol based on ethylene oxide, propylene oxide, and/or butylene oxide, a block copolymer based on ethylene oxide and oxide. propylene, polyethylene glycol, polypropylene glycol, polybutylene glycol, polytetrahydrofuran, polybutane diol or a mixture thereof. The polyether polyol is preferably a polytetrahydrofuran (flexible blocks of thermoplastic polyurethane therefore being blocks of polytetrahydrofuran) and/or a polypropylene glycol (flexible blocks of thermoplastic polyurethane therefore being blocks of polypropylene glycol) and/or a polyethylene glycol ( flexible blocks of thermoplastic polyurethane therefore being blocks of polyethylene glycol), preferably a polytetrahydrofuran having a number average molar mass of 500 to 15,000 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 relative 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 more preferably 1.

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

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

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

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 can be determined by GPC, preferably according to ISO 16014-1:2012. The chain extender preferably has two isocyanate-reactive groups (also called " functional groups "). You can use a single chain extender or a mixture of at least two chain extenders.

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 can be chosen 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 of these. 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.

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 index of the TPU. Indeed, when the proportion of chain extender increases, the hardness and melt viscosity of the TPU increase while the fluidity index of the TPU decreases. For the production of flexible TPU, preferably TPU having a Shore A hardness less than 95, more preferably 75 to 95, the compound reactive with the isocyanate and the chain extender can 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 an equivalent weight of hydroxyl greater than 200, more particularly 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 at 75, the compound reactive with the isocyanate and the chain extender can be used in a molar ratio of 1:5.5 to 1:15, preferably 1:6 to 1:12, preferably so as to that the mixture of compound reactive with isocyanate and chain extender has a hydroxyl equivalent weight of 110 to 200, more preferably of 120 to 180.

Advantageously, to prepare the TPU, the polyisocyanate, the compound reactive with the isocyanate, and preferably the chain extender are reacted, preferably in the presence of a catalyst, in quantities such that the ratio in equivalent of the NCO groups of the polyisocyanate relative to the sum of the hydroxyl groups of the isocyanate-reactive compound and the chain extender is 0.95:1 to 1.10:1, preferably 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 0.0001 to 0.1 parts by weight per 100 parts by weight of the TPU synthesis reagents.

Advantageously, 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.

Advantageously, the TPU can be a recycled TPU and/or a partially or completely biosourced TPU.

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

Advantageously, the TPU according to the invention has an OH function concentration of 0.002 meq/g to 0.6 meq/g, preferably 0.01 meq/g to 0.4 meq/g, more preferably 0 .03 meq/g to 0.2 meq/g. The concentration of OH function can be determined by NMR by following the conditions described in the article below: “Reactivity of isocyanates with urethanes: Conditions for allophanate formation”, Lapprand et al. , Polymer Degradation and Stability , Volume 90, No. 2, 2005, 363-373.

Very advantageously, the TPU is not crosslinked.

Polyethers with amide blocks (PEBA)

According to one embodiment, the thermoplastic elastomer is a polyether with amide blocks (PEBA). In these copolymers, the rigid block is a polyamide comprising at least one Z or XY type unit:

• Z being a lactam or an amino acid having 6 to 18 carbon atoms,
• X being a diamine having 4 to 48 carbon atoms
• Y being a diacid having 6 to 48 carbon atoms.

PEBAs result from the polycondensation of polyamide blocks (rigid or hard blocks) with reactive ends with polyether blocks (flexible or soft blocks) with reactive ends, such as, among others, polycondensation:

1) polyamide blocks with diamine chain ends with polyoxyalkylene blocks with dicarboxylic chain ends;

2) polyamide blocks with dicarboxylic chain ends with polyetherdiols (aliphatic polyoxyalkylene α,ω-dihydroxylated blocks), the products obtained being, in this particular case, polyetheresteramides.

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

Three types of polyamide blocks can advantageously be used.

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

As examples of dicarboxylic acids, mention may be made of 1,4-cyclohexyldicarboxylic acid, butanedioic, adipic, azelaic, suberic, sebacic, dodecanedicarboxylic, octadecanedicarboxylic acids and terephthalic and isophthalic acids, but also dimerized fatty acids. .

As examples of diamines, mention may be made of tetramethylene diamine, 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), paraamino-di-cyclohexyl-methane (PACM) , isophoronediamine (IPDA), 2,6-bis-(aminomethyl)-norbornane (BAMN) and piperazine (Pip).

Advantageously, polyamide 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 are used. In the PA XY notation, X represents the number of carbon atoms from diamine residues, and Y represents the number of carbon atoms from diacid residues, conventionally.

According to a second type, the polyamide blocks result from the condensation of one or more α,ω-aminocarboxylic acids and/or one or more lactams having from 6 to 12 carbon atoms in the presence of a dicarboxylic acid having 4 with 18 carbon atoms or a diamine. Examples of lactams include caprolactam, oenantholactam and lauryllactam. As examples of α,ω-amino carboxylic acid, mention may be made of aminocaproic, amino-7-heptanoic, amino-10-decanoic, amino-11-undecanoic and amino-12-dodecanoic acids.

Advantageously, the polyamide blocks of the second type are blocks of PA 10 (polydecanamide), PA 11 (polyundecanamide), PA 12 (polydodecanamide) or PA 6 (polycaprolactam). In PA X notation, X represents the number of carbon atoms from amino acid residues.

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

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

- linear or aromatic aliphatic diamine(s) having X carbon atoms;

- dicarboxylic acid(s) having Y carbon atoms; And

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

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

- in the presence of a chain limiter chosen from 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).

According to a variant of this third type, the polyamide blocks result from the condensation of at least two α,ω-aminocarboxylic acids or at least two lactams having 6 to 12 carbon atoms or of a lactam and a aminocarboxylic acid not having the same number of carbon atoms in the possible presence of a chain limiter.

As examples of aliphatic α,ω-aminocarboxylic acid, mention may be made of aminocaproic, amino-7-heptanoic, amino-10-decanoic, amino-11-undecanoic and amino-12-dodecanoic acids. As examples of lactam, we can cite caprolactam, oenantholactam and lauryllactam. As examples of aliphatic diamines, we can cite hexamethylenediamine, dodecamethylenediamine and trimethylhexamethylenediamine.

As examples of cycloaliphatic diacids, mention may be made of 1,4-cyclohexyldicarboxylic acid. As examples of aliphatic diacids, mention may be made of butane-dioic, adipic, azelaic, suberic, sebacic, dodecanedicarboxylic acids and dimerized fatty acids. These dimerized fatty acids preferably have a dimer content of at least 98%; preferably they are hydrogenated; these are for example products marketed under the brand "PRIPOL" by the company "CRODA", or under the brand EMPOL by the company BASF, or under the brand Radiacid by the company OLEON, and polyoxyalkylenes α,ω-diacids . As examples of aromatic diacids, mention may be made of terephthalic (T) and isophthalic (I) acids.

As examples of cycloaliphatic diamines, mention may be made of the isomers of bis-(4-aminocyclohexyl)-methane (BACM), bis- (3-methyl-4-aminocyclohexyl)methane (BMACM) and 2-2-bis- (3-methyl-4-aminocyclohexyl)-propane (BMACP), and paraamino-di-cyclohexyl-methane (PACM). Other commonly used diamines may be isophoronediamine (IPDA), 2,6-bis-(aminomethyl)-norbornane (BAMN), and piperazine.

As examples of polyamide blocks of the third type, the following can be cited:

- PA 66/6, where 66 designates hexamethylenediamine units condensed with adipic acid and 6 designates units resulting from the condensation of caprolactam;

- PA 66/610/11/12, where 66 designates hexamethylenediamine condensed with adipic acid, 610 designates hexamethylenediamine condensed with sebacic acid, 11 designates units resulting from the condensation of aminoundecanoic acid and 12 designates patterns resulting from the condensation of lauryllactam.

The notations PA X/Y, PA X/Y/Z, etc. relate to copolyamides in which X, Y, Z, etc. represent homopolyamide units as described above.

Advantageously, the polyamide blocks of the copolymer used in the invention comprise blocks of polyamide PA 6, PA 10, PA 11, PA 12, PA 54, PA 59, PA 510, PA 512, PA 513, PA 514, PA 516, PA 518, PA 536, PA 64, PA 66, PA 69, PA 610, PA 612, PA 613, PA 614, PA 616, PA 618, PA 636, PA 104, PA 109, PA 1010, PA 1012, PA 1013 , PA 1014, PA 1016, PA 1018, PA 1036, PA 10T, PA 124, PA 129, PA 1210, PA 1212, PA 1213, PA 1214, PA 1216, PA 1218, PA 1236, PA 12T, or mixtures or copolymers thereof; and preferably comprise blocks of polyamide PA 6, PA 10, PA 11, PA 12, PA 610, PA 612, PA 1010, PA 1012, or mixtures or copolymers thereof, more preferably blocks of polyamide PA 11 , PA 12, PA 6, PA 612, or mixtures or copolymers thereof.

Polyether blocks are made up of alkylene oxide units.

The polyether blocks may in particular be PEG (polyethylene glycol) blocks, i.e. made up of ethylene oxide units, and/or PPG (propylene glycol) blocks, i.e. made up of propylene oxide units, and/or PO3G (polytrimethylene glycol) blocks, i.e. made up of polytrimethylene glycol ether units, and/or PTMG blocks, i.e. 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.

It is also possible to use blocks obtained by oxyethylation of bisphenols, such as for example bisphenol A. These latter products are described in particular in document EP 613919.

The polyether blocks can also be made up of ethoxylated primary amines. As an example of ethoxylated primary amines, we can cite the products of formula:

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

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

PEBA can include ends of amine chains, provided that it includes ends of OH chains. PEBAs comprising amine chain ends can result from the polycondensation of polyamide blocks with dicarboxylic chain ends with polyoxyalkylene blocks with diamine chain ends, obtained for example by cyanoethylation and hydrogenation of aliphatic α,ω-dihydroxylated polyoxyalkylene blocks called polyetherdiols.

PEBAs are commercially available. In particular, we can mention the products marketed by Arkema under the name PEBAX®, by Evonik under the name Vestamid®, by EMS under the name Grilamid®, and by Sanyo under the name Pelestat®.

If the block copolymers described above generally comprise at least one polyamide block and at least one polyether block, the PEBAs within the meaning of this presentation can also comprise two, three, four (or even more) different blocks chosen from those described in the present description, since these blocks comprise at least polyamide and polyether blocks.

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

Particularly preferred PEBA copolymers in the context of the invention are copolymers comprising blocks: PA 10 and PEG; PA 10 and PTMG; PA 11 and PEG; PA 11 and PTMG; PA 12 and PEG; PA 12 and PTMG; PA 610 and PEG; PA 610 and PTMG; PA 6 and PEG; PA 6 and PTMG; PA 612 and PEG; PA 612 and PTMG.

The number-average molar mass of the polyamide blocks in the PEBA copolymer is preferably 400 to 20,000 g/mol, more preferably 500 to 10,000 g/mol.

The number average molar mass of the polyether blocks is preferably 100 to 6000 g/mol, more preferably 200 to 3000 g/mol. The number average molar mass is fixed by the chain limiter content. It can be calculated according to the relationship:

M _n = n _monomer x M _{w repeat unit} / n _{chain limiter} + M _{w chain limiter}

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

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

Advantageously, the mass ratio of the polyamide blocks relative to the polyether blocks of the copolymer is from 0.1 to 20, preferably from 0.5 to 18, even more preferably from 0.6 to 15. This mass ratio can be calculated by dividing the number average molar mass of the polyamide blocks by the number average molar mass of the polyether blocks. Advantageously, the copolymer with polyamide blocks and polyether blocks has a Shore D hardness of between 10D and 70D, preferably between 25D and 45D. Hardness measurements can be carried out according to ISO 7619-1.

Advantageously, the PEBA has a concentration in OH function of 0.002 meq/g to 0.2 meq/g, preferably of 0.005 meq/g to 0.1 meq/g, more preferably of 0.01 meq/g to 0 .08 meq/g and/or a COOH function concentration of 0.002 meq/g to 0.2 meq/g, preferably 0.005 meq/g to 0.1 meq/g, more preferably 0.01 meq/g g to 0.08 meq/g.

The COOH function concentration can be determined by potentiometric analysis and the OH function concentration can be determined by proton NMR. Measurement protocols are detailed in the article “Synthesis and characterization of poly(copolyethers-block-polyamides) - II. Characterization and properties of the multiblock copolymers”, Maréchal et al., Polymer, Volume 41, 2000, 3561–3580.

Preferably, the polyamide blocks of the copolymer with polyamide blocks and polyether blocks are blocks of polyamide 11, polyamide 12, polyamide 10, polyamide 6, polyamide 610, polyamide 612, polyamide 1010 and/or polyamide 1012, preferably polyamide 11, polyamide 12, polyamide 6 and/or polyamide 612; and/or the polyether blocks of the copolymer with polyamide blocks and polyether blocks are blocks of polyethylene glycol and/or polytetrahydrofuran.

Advantageously, the PEBA can be a recycled PEBA and/or a partially or completely biosourced PEBA.

Copolyester elastomers (TPE-E)

According to one embodiment, the thermoplastic elastomer is a copolyester elastomer (TPE-E).

According to one variant, the rigid block is a polyester comprising at least one XY pattern:

• X being a dicarboxylic acid
• Y being a diol.

The thermoplastic copolyester elastomer includes hard segments comprised of polyester repeating units derived from at least one aliphatic diol and at least one aromatic dicarboxylic acid or ester thereof, and soft segments selected from the group consisting of aliphatic polyether, aliphatic polyester, aliphatic polycarbonate, dimeric fatty acids and dimeric fatty diols and combinations thereof.

Rigid and soft blocks in TPE-E copolymers can be connected by urethane functions. These copolymers are particularly preferred due to their combination of mechanical and adhesive properties.

Aliphatic diols generally contain 2 to 10 carbon atoms, preferably 2 to 6 carbon atoms. Among these diols, mention may be made of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, butylene glycol, 1,2-hexane diol, 1,6-hexamethylene diol, 1 ,4-butanediol, 1,4-cyclohexane diol, 1,4-cyclohexane dimethanol and mixtures thereof. Preferably, 1,4-butanediol is used. The dicarboxylic acids may in particular be aromatic dicarboxylic acids among which there may be mentioned in particular terephthalic acid, isophthalic acid, phthalic acid, 2,5-furanedicarboxylic acid, 2,6-naphthalenedicarboxylic acid and 4,4'-diphenyldicarboxylic acid, and mixtures thereof. A mixture of 4,4'-diphenyldicarboxylic acid and 2,6-naphthalenedicarboxylic acid or a mixture of 4,4'-diphenyldicarboxylic acid and terephthalic acid is also very suitable. The mixing ratio between 4,4'-diphenyldicarboxylic acid and 2,6-naphthalenedicarboxylic acid or between 4,4'-diphenyldicarboxylic acid and terephthalic acid is preferably chosen between 40:60 - 60: 40 on a weight basis to optimize the melting temperature of the thermoplastic copolyester.

The hard segment preferably has a repeating unit chosen from the group consisting of ethylene terephthalate (PET), propylene terephthalate (PPT), butylene terephthalate (PBT), polyethylene bibenzoate, polyethylene naphthalate, polybutylene bibenzoate, polybutylene naphthalate, polypropylene bibenzoate and polypropylene naphthalate and combinations thereof. Preferably, the hard segment is butylene terephthalate (PBT), because thermoplastic copolyester elastomers comprising PBT hard segments exhibit favorable crystallization behavior and a high melting point, resulting in a thermoplastic copolyester elastomer having good elastic properties and excellent thermal and chemical resistance.

In a preferred embodiment, the composition comprises a thermoplastic copolyester elastomer having rigid and flexible segments, wherein the rigid segment is selected from PBT or PET, preferably PBT, and the flexible segment is selected from the group consisting of polybutylene adipate (PBA), polyethylene oxide (PEG), polypropylene oxide (PPG), polytetramethylene oxide (PTMG), PEG-PPG-PEG and their combinations, preferably PTMG, as this provides an article with low densities. In another preferred embodiment, the composition comprises a copolyether-ester thermoplastic elastomer composed of PBT and PTMG.

Advantageously, the rigid polyester block is a polymer of terephthalic acid and butane diol.

Advantageously, TPE-E has a Shore D hardness of between 10D and 70D, preferably between 25D and 45D.

Polyamides

The compositions of layers A and/or layer B may also comprise a non-elastomeric thermoplastic polymer, in particular a polyamide.

It may be an aliphatic or semi-aromatic polyamide. Preferably, it is an aliphatic polyamide. According to a particular embodiment, it is an aliphatic polyamide chosen from PA 11, PA 12, PA 1012, PA 612, PA1010, PA 610, PA 1212 and PA6.

According to a particular embodiment, layer A and/or layer B is in foamed form. Such foaming is particularly interesting for layer A.

In this case, the thermoplastic polymer has a reduced density. According to one embodiment, the thermoplastic polymer has a density less than 1, preferably less than 0.6 and even more preferably less than 0.3.

According to a particular embodiment, the thermoplastic polymer present in layer A is of the same family as the thermoplastic polymer present in layer B. Such a two-layer composite has particularly interesting properties after recycling. According to a preferred embodiment, it is a thermoplastic polymer from the same family but with a different structure. The difference in structure may arise in particular from a difference in the chemical formula of the monomer(s), or from a difference in chain or block length.

For example, the thermoplastic polymers in layer A and B may be one or more thermoplastic polyurethanes. Alternatively, it may be one or more polyamides, copolyamides or polyetheramide (PEBA).

According to a preferred alternative, the thermoplastic polymers in layers A and B can be more specifically chosen from polyetheramides (PEBA). This embodiment makes it possible to obtain two-layer composites with very good elastic return, low density and a more stable modulus between -20 and +40°C.

According to a particularly preferred embodiment, the thermoplastic polymer in layers A and B is a polymer of the same structure, for example both comprise a polyamide, or a thermoplastic polyurethane, or a polyetheramide (PEBA). According to an even more preferred embodiment, the thermoplastic polymer in layers A and B is a polyetheramide (PEBA).

The content of thermoplastic polymer in layer A is advantageously 30 – 100% by weight, more preferably 40 to 90% by weight, even more preferably 50 to 80% by weight. In embodiments, the thermoplastic polymer content of layer A is 30 to 35%, or 35 to 40%, or 40 to 45%, or 45 to 50%, or 50 to 55%, or 55 to 60%, or 60 to 65%, or 65 to 70%, or 70 to 75%, or 75 to 80%, or 80 to 85%, or 85 to 90%, or 90 at 95% or even from 95 to 100% by weight, relative to the weight of layer A.

The content of thermoplastic polymer in layer B is at least 25% by weight relative to the weight of layer B. Advantageously, layer B comprises 25 – 75% by weight, more preferably 30 to 70% by weight. , even more preferably from 40 to 65% by weight, relative to the total weight of layer B of a thermoplastic polymer as described above. In embodiments, the thermoplastic polymer content of layer B is 25 to 30%, or 30 to 35%, or 35 to 40%, or 40 to 45%, or 45 to 50%, or from 50 to 55% or from 55 to 60%, or from 60 to 65%, or from 65 to 70%, or even from 70 to 75% by weight relative to the weight of layer B.

Cross-linked rubber particles

Layer B comprises, in addition to a thermoplastic polymer, crosslinked rubber particles.

The crosslinked rubber particles used in the composites of the invention are characterized by a particular specific surface area, comprised between 0.01 m ² /g and 0.5 m ² /g, advantageously between 0.05 m 2 /g and 0.3 m/g, very advantageously between 0.08 and 0.2 m²/g. This specific surface area is measured by the BET method as described in Shen et al. Build. Build. Mater. 2009, 23 (1), 304-310.

The crosslinked rubber particles preferably have a particular particle size, in particular a specific diameter D50, D90 and/or D10.

The crosslinked rubber particles thus preferably have a median diameter D50 of between 2 and 500 µm, preferably between 50 and 300 µm, and more preferably between 60 and 200 µm.

The diameter D90 of the particles can in particular be between 10 and 800 µm, preferably between 80 and 500 µm, and more preferably between 100 and 300 µm.

The diameter D10 of the particles can in particular be comprised from 1 to 300 µm, preferably from 5 to 200 µm, and more preferably from 10 to 100 µm.

The term “ diameter ” or “ D ” of the powder is understood to mean the mass average diameter of a powdery material, as measured according to the “Ro-tap sieve tests” method using machines such as the RX- 94 Duo or the RO-TAP Premium marketed by WS Tyler, equipped with sieves complying with the ISO 3310-1:2016 standard. There are different diameters. More specifically, the D50 designates the median diameter by mass, respectively the diameters below which 50% by mass of the particles are located. In addition, the D10 and D90 respectively designate the diameters below which 10 or 90% by mass of the particles are located.

The rubber in the crosslinked rubber powder may be a natural or synthetic rubber or a mixture thereof.

The rubber used in the manufacture of crosslinked rubber particles can in principle be of any type, in particular it can be a sulfur vulcanized rubber. Rubber can come from a wide variety of sources. By way of example, mention may be made of bromobutyl rubber, butyl rubber, polyisoprene rubber, polynorbornene rubber, ethylene-propylene rubber (EPR), ethylene-propylene-diene rubber (EPDM). ), nitrile rubber, carboxylated nitrile rubber, polychloroprene rubber (neoprene rubber), polysulfide rubbers, polyacrylic rubbers, silicone rubbers, chlorosulfonated polyethylene rubbers, rubbers comprising polybutadiene, styrene butadiene rubbers, and the like, as well as various mixtures thereof.

The rubber of the crosslinked rubber particles may contain from 0 to 50% by weight, preferably from 5 to 40% by weight of a synthetic rubber or a mixture of synthetic rubbers.

The rubber of the crosslinked rubber particles may contain 10 to 80% by weight, preferably 15 to 70% by weight of natural rubber.

The natural rubber may in particular be chosen from cis-1,4-polyisoprene or trans-1,4-polyisoprene.

The rubber of the crosslinked rubber particles may contain a styrene and butadiene rubber, preferably in a content greater than 5% by weight, more preferably greater than 10% by weight.

Preferably, the crosslinked rubber particles come from used tires, particularly at the end of their life and/or having driven at least 20 km, especially those that we wish to recycle. Used tire rubber can thus include functions produced during thermo-oxidation reactions in a content higher than that observed in rubber virgin of any use. These functions may in particular be phenylhydrazone, carbonyl such as ketones, hydroxyl or sulfenic acid, advantageously carbonyl and sulfenic acid functions.

Without wishing to be bound by a particular theory, these polar functions could make it possible to improve the interactions between the matrix based on thermoplastic elastomer and the crosslinked rubber particles and thus the physical properties of the composite material.

As an example of a source of crosslinked rubber particles, we can cite the rubber compound recovered during the polishing of vehicle tire treads, as part of regrooving procedures. However, rubber compound can come from a wide variety of sources, including whole tire rubber, tire sidewalls, tire inner liners, tire carcasses, power transmission belts, tire belts, conveyor, hoses and a wide variety of other rubber products. Accordingly, rubber particles typically comprise a mixture of natural rubber and various synthetic rubbers.

Accordingly, the crosslinked rubber particles used in accordance with the present disclosure are typically formed from a blend of natural rubber, polyisoprene synthetic rubber, polybutadiene rubber and styrene-butadiene rubber. However, the crosslinked rubber particles used according to the invention can be a mixture of two or more of these rubbers or it can be composed of a single type of rubber. For example, the crosslinked rubber particles may consist of only natural rubber, synthetic polyisoprene rubber, styrene-butadiene rubber, a blend of natural rubber and polybutadiene rubber, or a blend of natural rubber and rubber styrene-butadiene.

Cross-linked rubber particles can be prepared using different methods. For example, they can be obtained by a process of crushing a tire, advantageously at the end of its life, having driven more than 20 km. Different grinding processes exist such as, for example, mechanical grinding at room temperature, cryogenic grinding, grinding using water jets (called “waterjet” in English) or even micronization. Preferably, the crosslinked rubber particles are obtained by grinding a tire with a water jet, a technique also called water jet cutting.

The crosslinked rubber particles can contain from 1 to 70%, preferably from 5 to 50%, more preferably from 10 to 40% of carbon black and/or silica.

In one embodiment, the crosslinked rubber particles include carbon black and silica. Advantageously, the level of silica is 2 times, very advantageously 5 times higher than the level of carbon black, the level representing the content by weight relative to the total weight of the particles.

Furthermore, the crosslinked rubber particles may comprise less than 10%, advantageously less than 5%, very advantageously less than 1% of fibrous material.

In addition, the crosslinked rubber particles may contain from 0.05 to 5% by weight, preferably from 0.1% to 2.5% by weight of zinc oxide.

Layer B comprises 1 to 75%, preferably 10 to 70, more preferably 30 to 65, in particular 40 to 60% by weight relative to the total weight of layer B of crosslinked rubber particles, in particular from recycled tires. Layer B may contain in particular 1 to 5%, or 5 to 10%, or 10 to 15%, or 15 to 20%, or 20 to 25%, or 25 to 30%, or 30 to 35%, or 35 at 40%, or 40 to 45%, or 45 to 50%, or 50 to 55% or 55 to 60%, or 60 to 65%, or 65 to 70%, or 70 to 75% by weight of rubber particles reticulated, particularly from recycled tires.

Additives

In order to achieve the desired properties, the compositions of layers A and/or B may also contain one or more additives.

The additive(s) may in particular be chosen from catalysts, antioxidants, thermal stabilizers, UV stabilizers, light stabilizers, lubricants, flame retardants, chain extenders, antistatic agents, optical brighteners, nucleating agents, plasticizers, pigments and dyes.

According to one embodiment, layer A and/or B respectively comprise 0 to 5% by weight, preferably 0.1 to 4%, in particular 1 to 2% by weight of additives relative to the total weight of the composition .

Compatibilizing agents

The compositions of layers A and/or B may also contain one or more compatibilizing agents in order to perfect the homogeneity of the mixture.

The presence of a compatibilizing agent is particularly advantageous in layer B. Indeed, depending on the nature of the thermoplastic elastomer and the rubber powder, the presence of a compatibilizing agent can be advantageous in order to obtain good dispersion of crosslinked rubber powder particles within the matrix.

Physical cohesion can result for example from a coating of the rubber particles, from an entanglement of the polymer and/or copolymer chains and/or from Van Der Waals or hydrogen bonds between all or part of the constituents of the composition.

As compatibilizing agents, mention may in particular be made of copolyamides, impact modifiers, thermoplastic polyurethanes (TPU), polymers containing silane groups, siloxanes, or a mixture of these.

The compatibilizing agent advantageously carries reactive functions which can, preferably, react with the alcohol, isocyanate, amine or carboxylic acid functions carried by the thermoplastic elastomer.

In embodiments, at least part of the thermoplastic elastomer is covalently linked to at least part of the compatibilizer by a urea, urethane, amide, ester or alkoxysilane function. Preferably a quantity less than or equal to 10% by weight, more preferably less than or equal to 5% by weight, of the thermoplastic elastomer is covalently linked to at least part of the compatibilizing agent by a urea, urethane function , amide, ester or alkoxysilane.

According to one embodiment, layer A and/or B comprises 0 to 40%, preferably 0 to 20%, and in particular 0 to 10% by weight of compatibilizing agent. According to one embodiment, layer A and/or B comprises 0 to 5%, 5 to 10%, 10 to 15%, 15 to 20%, 20 to 25%, 25 to 30%, 30 at 35% or from 35 to 40% by weight of one or more compatibilizing agents relative to the total weight of the composition of layer A or B respectively.

Loads and reinforcements

The fillers and reinforcements may also be present in the composition of layer A and/or B. The tire particles present in layer B are not considered in the fillers and reinforcements.

We can particularly mention fibrous reinforcements such as short or continuous glass fibers, short or continuous carbon fibers, possibly coated with resin, or even fibers of plant materials or mineral fibers. Alternatively, non-fibrous reinforcements can be considered, for example solid glass beads, but also lightweight reinforcements such as hollow glass beads or encapsulated foaming agents.

According to one embodiment, the layers A and/or B comprise from 0 to 70% by weight, preferably 10 to 60% by weight, and in particular 20 to 50, in particular 30 to 40% by weight of one or several fillers and/or reinforcements relative to the total weight of the composition of layer A or B respectively.

Preferably, however, layer B is devoid of fillers or reinforcements.

Preferably, layer A comprises 0 to 70% by weight, preferably 10 to 60% by weight, more preferably 20 to 50% and most particularly 30 to 40% by weight of fillers. In embodiments, the filler content of layer A is 0 to 5%, or 5 to 10%, or 10 to 15%, or 15 to 20%, or 20 to 25%, or from 25 to 30%, or from 30 to 35%, or from 35 to 40%, or from 40 to 45%, or from 45 to 50%, or from 50 to 55%, or from 55 to 60%, or from 60 to 65%, or 65 to 70% by weight relative to the weight of layer A.

The compositions intended to form layer A and layer B respectively can be manufactured by any of the mixing processes known in the field of plastics processing, in particular by means of an extruder, in particular a co-kneader.

Advantageously, the preparation process comprises a step of shaping the mixture in the form of granules, filaments or powder. When the mixture is put into powder form, it is preferably first put into the form of granules and then the granules are ground into powder. Any type of mill can be used, such as a hammer mill, pin mill, attrition disc mill or impact classifier mill. Preferably, the mixture is put in the form of granules.

According to a particularly preferred embodiment, the composition intended for layer A of the two-layer composite comprises:

• from 30 to 90% by weight, preferably from 40 to 70% by weight, of at least one thermoplastic polymer chosen from polyamides and thermoplastic elastomers;
• from 0 to 5% by weight, preferably from 0.1 to 4% by weight, in particular from 1 to 2% by weight of additives;
• 0 to 70% by weight, preferably 10 to 60% by weight, and in particular 20 to 50, in particular 30 to 40% by weight of fillers and reinforcements; And
• from 0 to 40% by weight, preferably from 0 to 20% by weight, in particular from 0 to 10% by weight of compatibilizing agents.

According to a particularly preferred embodiment, the composition intended for layer B of the two-layer composite comprises:

• from 25 to 90% by weight, preferably from 40 to 70% by weight, of at least one thermoplastic polymer chosen from polyamides and thermoplastic elastomers;
• from 10 to 75% by weight, preferably from 30 to 65% by weight, and in particular 40 to 60% by weight of crosslinked rubber particles, preferably having a specific surface area of between 0.08 m ² /g and 0 .50 m ² /g,
• from 0 to 5% by weight, preferably from 0.1 to 4% by weight, in particular from 1 to 2% by weight of additives;
• from 0 to 40% by weight, preferably from 0 to 20% by weight, in particular from 0 to 10% by weight of compatibilizing agents.

According to one embodiment, the ratio between the thickness of layer A and the thickness of layer B is between 1 and 400, and preferably between 1 and 10.

Composite manufacturing process

Advantageously, the two-layer composites of the invention are easy and quick to manufacture. In particular, it is not necessary to carry out an elastomer crosslinking step.

Also, according to another aspect, the invention aims at a method of manufacturing a two-layer composite as described above comprising a step consisting of bringing the material of layer A and/or the material of layer B to the state melted then putting the two materials into contact with each other.

The materials intended to form layer A and layer B of the composite can be, if necessary, mixed according to any of the processes known for this purpose, in particular by compounding for example in an extruder.

Such a mixing process by compounding may comprise the steps consisting of:

1. mix, preferably in an extruder, advantageously in a co-kneader or a twin-screw extruder, the different components of the composition;
2. optionally, shape the composition obtained in step (a) in the form of granules, filaments or powder, and/or
3. recover the composition obtained.

The possible foaming of the material intended to form layer A or layer B can be carried out by one of the methods known for this purpose, for example by means of a chemical foaming agent or by impregnation with a gas as described. for example in patent application WO 2022/058680 A1.

The contacting of the two materials intended to form layer A and layer B can be carried out in a conventional manner, according to one of the well-known plastics processing processes. In this respect, we can cite in particular overmolding, bi-injection, thermocompression, injection-foaming, extrusion, coextrusion, thermoforming, blow molding or even low pressure injection molding.

For reasons of ease of manufacturing and recycling, it is preferred that the process does not include an assembly step using an adhesive.

When an adhesive is used, it can be chosen from adhesives known for this purpose, in particular from copolyamides sold under the name Platamid® by the company Arkema or Thermelt® from Bostik or polyurethane adhesives.

Uses

The composites of the invention can be very useful in the manufacture of any article in which its properties, in particular non-slip properties, and its resistance to abrasion, are of interest.

Also, according to another aspect, the invention aims at the use of the two-layer composite of the invention as a component of shoes; parts of sports equipment such as parts for ski poles, frames for ski masks, handles for rackets and golf clubs and goalkeeper gloves; treadmills ; aquatic equipment such as diving shoes, mask parts or snorkels; spectacle frame parts, such as sleeve, temples, or plates; shock and/or vibration absorbers; cases for external batteries; automobile parts, including gaskets and end caps; toys ; watch straps; rollers; wheels; machine control keys; seals ; or as a component of transport belts.

Preferably, the composite of the invention can be used for the manufacture of shoe soles, in particular sports shoes, city shoes or even safety shoes; as rolls; wheels; as shock and/or vibration absorbers; or as sports equipment sleeves.

Items

Consequently, according to another aspect, the invention relates to an object comprising the composite of the invention.

In particular, the object can be chosen from shoes; sports equipment such as ski poles, ski masks, rackets, golf clubs, goalkeeper gloves; treadmills ; aquatic equipment such as diving shoes, masks and snorkels; spectacle frames; shock and/or vibration absorbers; cases for external batteries; automobile parts, including gaskets and end caps; toys ; watch straps; rollers; wheels; machine control keys; seals ; and conveyor belts.

The invention will be explained in more detail in the examples which follow.

Article recycling process

As mentioned, the two-layer composite of the invention has the advantage of being easily recyclable.

Also, according to another aspect, the invention also relates to a process for recycling the article comprising the composite according to the invention, which process comprises the following steps:

(a) Grinding the article comprising the used composite to obtain a ground material;

(b) Heating the ground material until it melts to form a molten mass; And

(c) Extrusion of the molten mass obtained in step (b) in the form of granules.

In a preferred embodiment, virgin material can be added before or after step b.

Composition obtained by the recycling process

According to another aspect, the invention also targets the composition capable of being obtained by the recycling process mentioned.

Use of the composition obtained by the recycling process

Advantageously, the composition obtained by recycling objects comprising the two-layer composite of the invention can be reused for the manufacture of objects. Advantageously, it is possible to reuse this composition for the manufacture of the objects from which it is derived, in particular those mentioned above.

Also, according to a final aspect, the invention aims to use the composition obtained by recycling objects comprising the two-layer composite of the invention for the manufacture of objects. Advantageously, these objects are those mentioned above for the use of the two-layer composites of the invention.

It is particularly preferred that the composition obtained by the recycling process is used for the manufacture of recycling objects from which it is derived.

Unless otherwise stated, percentages are expressed by weight relative to the total weight of the composition.

Abrasion resistance is measured according to ISO 4649:2010.

The following materials were used:

PEBA n°1: PEBAX®40R53 commercially available from Arkema.

TPU: Elastollan® 1185A commercially available from BASF.

AP 11 charged

glass fibers: Rilsan® BZM8 O TL available commercially from Arkema.

PA11: Rilsan® FMNO commercially available from Arkema

PA 11/fibers

continuous carbon: prepregs (or tapes) made up of Toray T700 24k carbon fibers and PA11 (TNat 2P, Arkema) obtained by powder fluidized bed pre-impregnation process as described in patent application WO/2020126997.

Powder of

rubber: TyreXol® CW 50, made from used tires commercially available from TRS. The powder has a specific surface area greater than 0.08 g/m ² , The diameter D50 of this powder is less than 175 µm and the diameter D90 is less than 375 µm.

SEBS-g-MAH: Kraton® FG1901 commercially available from Kraton

EXAMPLES EI1 to EI5

From these components, different composites EI1 to EI5 were prepared. Their composition, in mass percentage, is indicated in Table 1 below.

Manufacturing of layer B:

In examples EI1 and EI3, the mixtures of PEBA and rubber powder intended to manufacture layer B are made using a Buss PR-46 15D mixer. The temperature of the sheath and the recovery screw are set at 175°C and the screw speed of the co-mixer is set at 250 rpm with a flow rate of 15 kg/h. The recovery screw is set at 60 rpm. The granules obtained are then dried under reduced pressure at 80°C in order to achieve a humidity level of less than 0.08%.

Plates measuring 100 x 100 mm and 2 mm thick as well as pucks measuring 16 mm in diameter and 6 mm thick are injected using an ENGEL 160T press. The following parameters are applied during injection:

- Sheath temperature: 150-170°C.

- Nozzle temperature: 170°C.

- Mold temperature: 20°C.

- Cycle time: < 60 seconds

The plates thus manufactured are then used both for measuring slip resistance and for the overmolding step.

The pucks are used to measure abrasion resistance since this layer will be in contact with the ground.

In the inventive examples EI2 and EI4, the mixtures of TPU and rubber powder constituting layer B are produced using a Buss PR-46 15D mixer. The compositions of the mixture are specified in Table 1 below. The temperature of the sheath and the recovery screw are set at 190°C and the screw speed of the co-mixer is set at 250 rpm with a flow rate of 15 kg/h. The recovery screw is set at 60 rpm. The granules obtained are then dried under reduced pressure at 80°C in order to achieve a humidity level of less than 0.08%.

From these granules, plates of 100 x 100 mm and 2 mm thickness are prepared as well as pucks of 16 mm in diameter and 6 mm in thickness by injection using an ENGEL 160T press. . The following parameters are applied during injection:

- Sheath temperature: 170-190°C.

- Nozzle temperature: 190°C.

- Mold temperature: 20°C.

- Cycle time: < 60 seconds

The plates thus manufactured are then used both for measuring slip resistance and for the overmolding step.

The pucks are, for their part, used to measure abrasion resistance since this layer will be in contact with the ground.

In inventive example EI5, a mixture is prepared comprising 40% by weight of PA11 Rilsan® FMNO, 50% by weight of CW50 powder and 10% by weight of a compatibilizer based on styrene-butadiene-ethylene-styrene grafted with maleic anhydride (SEBS-g-MAH) using a BUSS PR-46 mixer. The temperature of the sleeves is set at 200°C, the rotation speed of the co-mixer at 250 rpm and that of the recovery screw at 60 rpm. The flow rate is set at 10 kg/h. The rods obtained are granulated then the granules are dried at 80°C under reduced pressure overnight in order to obtain a residual humidity of 0.08%. The granules are used both for overmolding and for the injection of pucks (16 mm in diameter and 6 mm thick) which will be used to determine the resistance to abrasion. The following settings are applied during injection:

- Sheath temperature: 190-215°C.

- Nozzle temperature: 215°C.

- Mold temperature: 60°C.

- Cycle time: < 60 seconds

Manufacturing of layer A:

The plates obtained are inserted into a 100 x 100 x 4 mm mold then overmolded with material forming layer A to form the two-layer composite according to the invention.

In the case of examples EI1 and EI4, the TPU Elastollan®1185A is injected using an ENGEL 160T injection press onto the plate placed in the mold using the following injection parameters:

- Sheath temperature: 170-190°C.

- Nozzle temperature: 190°C.

- Mold temperature: 20°C.

- Cycle time: < 60 seconds

In the case of example EI2, Pebax® 40R53 is injected onto the TPU plates loaded with rubber particles using an ENGEL 160T injection press on the plate placed in the mold using the following injection parameters:

- Sheath temperature: 150-170°C.

- Nozzle temperature: 170°C.

- Mold temperature: 20°C.

- Cycle time: < 60 seconds

In the case of example EI3, PA11 Rilsan® BZM8 loaded with glass fibers is injected using an ENGEL 160T injection press onto the plate placed in the mold using the following injection parameters:

- Sheath temperature: 290°C.

- Nozzle temperature: 290°C.

- Mold temperature: 60°C.

- Cycle time: < 60 seconds

In the case of example EI5, a composite plate is made from pre-impregnated tapes (otherwise called tapes) made up of Toray T700 24k carbon fibers and PA11 (TNat 2P, Arkema). The prepregs are composed of 66% by weight of carbon fibers and 34% by weight of PA11 polymer. They have an average width of 12.7 mm and are obtained by a fluidized bed impregnation process of powders as described in patent WO20126997 A1.

These tapes were deposited using a CORIOLIS C-Solo robot equipped with a Laser heating source and a pressure roller. The preform thus obtained is consolidated under a heating press at 230°C.

The plate thus consolidated is cut to the desired dimensions for the intended application, i.e. 100x100mm ² , using a water-cooled circular saw. The thickness of the plate is measured using a caliper in the four corners of the plate thus cut. In our example, we measure an average thickness of 1.03mm.

The plate thus manufactured is introduced into a 100 x 100 x 4 mm mold then overmolded with the mixture comprising 40% PA11, 50% CW50 powder and 10% SEBS-g-MAH.

The overmolding and injection of the pucks are carried out using an ENGEL 160T press. The following parameters are applied during injection:

- Sheath temperature: 190-215°C.

- Nozzle temperature: 215°C.

- Mold temperature: 60°C.

- Cycle time: < 60 seconds

[ Table 1 ] Compositions of the composites according to the invention Example
Layer B Layer A Adhesive
Thermoplastic polymer
Content [% by weight] Rubber Content [% by weight] Thermoplastic polymer
[% in weight] EI1 Pebax® 40R53 60 TyreXol®CW 50 40 TPU Elastollan® 1185A NO EI2 TPU Elastollan® 1185A 50 TyreXol® CW50 50 PEBAX® 40R53 NO EI3 Pebax® 40R53 60 TyreXol® CW50 40 PA 11 Rilsan® BZM8 O TL NO EI4 TPU Elastollan® 1185A 60 TyreXol® CW50 40 TPU Elastollan® 1185A NO EI5 40% Rilsan® FMNO + 10% Kraton® FG1901 50 TyreXol® CW50 50 PA11 composite filled with continuous carbon fibers NO

The properties of the different composites are then evaluated according to the following criteria:

1. Measuring slip resistance:

The static (Ks) and dynamic (Kd) coefficients of the manufactured composites were measured according to the ASTM D1894 standard by sliding on a water bed at a speed of 150 mm/min on an aluminum sliding track. The sample is towed by a CRITERION C42.503 dynamometer equipped with a 10N force cell. The plates are first cut using a cookie cutter to a size of 63.5 mm x 63.5 mm. Five measurements are taken per sample.

Slip resistance is defined as satisfactory if Kd and Ks are greater than 0.45.

1. Abrasion resistance measurement

The abrasion resistance of the B layers was measured according to ISO 4649 using a rotating abrasive cylinder. Injected pads with a diameter of 16 mm and a thickness of 6 mm are used. Abrasion resistance is considered satisfactory if the variation in volume is less than 70 mm ³ .

1. Manufacturing time

The manufacturing process is considered rapid if the manufacturing time of layers A and B and their assembly is less than 5 min. Manufacturing time is considered slow when it exceeds 5 minutes.

The results of these evaluations for the different composites are detailed in Table 2 below.

[Table 2] Properties of the composites according to the invention Example Slip resistance Abrasion resistance Manufacturing time EI1 + + Fast EI2 + + Fast EI3 + + Fast EI4 + + Fast EI5 + + Fast

All the results show that the specific combination of a polymer layer loaded with crosslinked rubber particles with a layer of thermoplastic elastomer makes it possible to obtain a composite combining anti-slip behavior with good resistance to wear and tear. abrasion which can be manufactured in a short time.

As variants of the composite can be considered, in particular, to provide a layer of thermoplastic polymer in the form of foam to obtain a lightweight composite or, on the contrary, loaded with reinforcements in order to give the composite greater rigidity.

Advantageously, the composite of the invention does not need to be assembled with an adhesive.

Claims (19)

Two-layer composite comprising a layer A and a layer B, in which:

• layer A comprises at least 30% by weight relative to the weight of layer A of at least one thermoplastic polymer chosen from thermoplastic elastomers and polyamides; And
• the layer B comprises at least 25% by weight relative to the weight of layer B of at least one thermoplastic polymer chosen from thermoplastic elastomers and polyamides and 1 to 75% by weight relative to the total weight of layer B of crosslinked rubber particles.

Bilayer composite according to claim 1, in which the thermoplastic elastomer in layer A and/or B is chosen from thermoplastic polyurethanes (TPU), polyetheramides (PEBA) and copolyester elastomers (TPE-E). Two-layer composite according to one of claims 1 to 2, in which the thermoplastic polymer in layer A is chosen from polyamides or thermoplastic elastomers, in particular chosen from thermoplastic polyurethanes (TPU), styrene and butadiene block copolymers (SBS ) and styrene, ethylene and butadiene block copolymers (SEBS), polyester elastomers such as ether ester block copolymers (COPE) and polyamide elastomers such as amide block polyethers (PEBA). Two-layer composite according to one of claims 1 to 3, in which the thermoplastic polymer in layer B is chosen from polyamides or thermoplastic elastomers, in particular chosen from thermoplastic polyurethanes (TPU), styrene and butadiene block copolymers (SBS ) and styrene, ethylene and butadiene block copolymers (SEBS), polyester elastomers such as ether ester block copolymers (COPE) and polyamide elastomers such as amide block polyethers (PEBA). Two-layer composite according to one of claims 1 to 4, in which the thermoplastic polymer in layer A and the thermoplastic polymer in layer B belong to the same polymer family. Two-layer composite according to one of claims 1 to 5, in which in layer A, the thermoplastic polymer has a density less than 1, preferably <0.3. Two-layer composite according to one of claims 1 to 6, in which the crosslinked rubber particles are obtained by grinding used tires. Two-layer composite according to one of claims 1 to 7, in which layer A comprises 10 to 70% by weight of fillers relative to the weight of layer A. Bilayer composition according to one of claims 1 to 8, in which the thermoplastic polymer in layer A and in layer B are chosen respectively from polyamides or thermoplastic polyurethanes (TPU) or polyetheramides (PEBA). Composite according to one of claims 1 to 9, in which layer A is at least partially in direct contact with layer B. Method of manufacturing a two-layer composite according to one of claims 1 to 10, comprising a step consisting of bringing the material of layer A and/or the material of layer B to the molten state then placing the two materials in contact with each other. Manufacturing method according to claim 11, in which the assembly of the layers of the two-layer composite is carried out by overmolding, bi-injection, injection-foaming, thermocompression, extrusion, coextrusion, thermoforming, blow molding or even by low pressure injection molding . Method of manufacturing a two-layer composite according to one of claims 1 to 10, devoid of an assembly step using an adhesive. Use of a two-layer composite according to one of claims 1 to 10 as a shoe component; parts of sports equipment such as parts for ski poles, frames for ski masks, handles for rackets and golf clubs and goalkeeper gloves; treadmills ; aquatic equipment such as diving shoes, mask parts or snorkels; spectacle frame parts, such as sleeve, temples, or plates; shock and/or vibration absorbers; cases for external batteries; automobile parts, including gaskets and end caps; toys ; watch straps; rollers; wheels; machine control keys; seals ; or as a component of transport belts. Object comprising the two-layer composite according to one of claims 1 to 10. Object according to claim 15, chosen from shoes; sports equipment such as ski poles, ski masks, rackets, golf clubs, goalkeeper gloves; treadmills ; aquatic equipment such as diving shoes, masks and snorkels; spectacle frames; shock and/or vibration absorbers; cases for external batteries; automobile parts, including gaskets and end caps; toys ; watch straps; rollers; wheels; machine control keys; seals ; and conveyor belts. Process for recycling the used object according to claim 15 or 16, comprising the following steps:
(a) Grinding of said object according to claim 15 or 16 used to obtain a ground material;
(b) Heating the ground material until it melts to form a molten mass; And
(c) Extrusion of the molten mass obtained in step (b) in the form of a granule. Composition capable of being obtained by the recycling process according to claim 17. Use of the composition according to claim 18 for the manufacture of objects as defined in claim 14.