AU2022354155A1 - Item made of rubber that is resistant to mechanical attack - Google Patents

Abstract

The invention relates to an item made of rubber, selected from among tires for civil engineering vehicles, caterpillar tracks and conveyor belts, that exhibits a good performance trade-off between resistance to mechanical attack and hysteresis. This rubber item comprises a composition based on at least: an elastomeric matrix comprising at least 55% by weight of at least one isoprenic elastomer having a molar cis-1,4 bond content of at least 90%; a thermoplastic elastomer comprising at least one polyether elastomer block and at least one non-styrenic thermoplastic block, the thermoplastic elastomer having a melting point, Tf, within a range from 130°C to 175°C; 10 to 60 PHR carbon black; 5 to 30 PHR silica; and a crosslinking system; the carbon black representing from 55% to 95% by weight relative to the total weight of carbon black and silica.

Description

DESCRIPTION TITLE: ITEM MADE OF RUBBER THAT IS RESISTANT TO MECHANICAL ATTACK

The present invention relates to rubber articles, in particular tyres for civil engineering vehicles, caterpillar tracks or conveyor belts, which must have good resistance to mechanical attacks.

Tyres of civil engineering vehicles have to have very different technical characteristics from tyres intended for vehicles which run exclusively on roads (that is to say a bituminous surface), since the nature of the off-road surfaces on which they are mainly moving is very different and in particular much more aggressive, due to its stony nature. Moreover, unlike tyres for passenger vehicles, for example, tyres for large civil engineering machines must be able to withstand a load which may be extremely heavy. Consequently, the known solutions for tyres that run on a bituminous surface are not directly applicable to off-road tyres such as tyres for civil engineering vehicles.

Conventionally, the treads of civil engineering vehicle tyres consist of natural rubber as elastomer. These treads are known to exhibit good wear resistance, while at the same time exhibiting good hysteretic performance for the application in question, avoiding an excessive rise in temperature of the tyre.

During running, a tread is subjected to mechanical stresses and attacks resulting from direct contact with the ground. In the case of a tyre fitted to a vehicle bearing heavy loads, the mechanical stresses and the attacks to which the tyre is subjected are magnified under the effect of the weight bome by the tyre. Tyres for mining vehicles in particular are subjected to high stresses, both locally: running over the indenting macrobodies represented by the stones from which the tracks are formed (crushed rock), and also globally: high torque transmission since the slopes of the tracks for entering or leaving the "pits", or open-air mines, are about 10%, and high stresses on the tyres during U-turns performed by the vehicles for loading and unloading manoeuvres.

The consequence of this is that the incipient cracks which are created in the tyre tread under the effect of these stresses and these attacks have a tendency to further propagate at the surface of or inside the tread, which can bring about localized or generalized tearing of the tread. These stresses can therefore result in damage to the tread and can thus reduce the lifetime of the tread and thus of the tyre. A tyre running over stony ground is highly exposed to mechanical attacks, and therefore to incipient cracks and cuts. This is particularly true for the tyres equipping civil engineering vehicles which are moving about generally in mines and quarries.

It is thus important to have available tyres for vehicles intended to run on stony ground surfaces and bearing heavy loads, the tread of which exhibits a resistance to crack initiation and/or propagation which is sufficiently strong to improve the lifetime of the tread.

Furthermore, it remains advantageous for the solutions provided in order to solve this problem not to be disadvantageous to the other properties of the rubber composition, in particular the hysteresis reflecting the heat dissipation capacity of the composition. This is because the use of a composition that is too hysteretic in a tyre may be apparent by a rise in the internal temperature of the tyre, which may result in a reduction in the durability of the tyre.

In the light of the aforementioned, there is a constant objective of improving the resistance to mechanical attack of civil engineering vehicle tyre tread compositions based on natural rubber, preferably without excessively penalizing the hysteretic performances. Thus, improving the performance compromise between resistance to attack and hysteresis remains a constant concern of manufacturers, particularly in the field of tyres for civil engineering vehicles.

This performance compromise is also advantageous for rubber caterpillar tracks intended to be fitted to construction vehicles or agricultural vehicles for the same reasons as set out above. It is also advantageous for conveyor belts (or belt conveyors) which can receive large amounts of earth, ore, stones, rocks and which can dissipate huge amounts of energy via internal dissipation to the material constituting the belt during the punching of the belt between its load and the support driving it.

Solutions have been provided to improve this compromise. For example, application WO 2016/202970 Al which proposes using a specific composition, the elastomeric matrix of which comprises a diene elastomer selected from the group consisting of polybutadienes, butadiene copolymers and mixtures thereof, and a styrene thermoplastic elastomer comprising at least one rigid styrene segment and at least one flexible diene segment comprising at least 20% by weight of conjugated diene units.

However, manufacturers are always looking for solutions to further improve the performance compromise between resistance to attacks and hysteresis.

Continuing its research, the applicant has unexpectedly discovered that the use of a thermoplastic elastomer comprising at least one polyether elastomer block and at least one non-styrene thermoplastic block having a specific melting temperature, in the presence of a specific blend of filler, in a rubber composition comprising predominantly an isoprene elastomer having a molar content of 1,4-cis bond of at least 90%, makes it possible to improve the resistance to mechanical attack without penalizing the compromise in performance between the resistance to mechanical attack and hysteresis.

Thus, a subject of the invention is a rubber article comprising a composition based on at least: - one elastomeric matrix comprising at least 55% by weight of at least one isoprene elastomer having a molar content of 1,4-cis bond of at least 90%, - one thermoplastic elastomer comprising at least one polyether elastomer block and at least one non-styrene thermoplastic block, the thermoplastic elastomer having a melting temperature, Tm, within a range extending from 130°C to 175°C, - 10 to 60 phr of carbon black, - 5 to 30 phr of silica, and - a crosslinking system, the carbon black representing from 55% to 95% by weight, relative to the total weight of carbon black and silica, the rubber article being selected from the group consisting of tyres for civil engineering vehicles, caterpillar tracks and conveyor belts.

I- DEFINITIONS The expression "composition based on" should be understood as meaning a composition including the mixture and/or the product of the in situ reaction of the various constituents used, some of these constituents being able to react and/or being intended to react with each other, at least partially, during the various phases of manufacture of the composition; the composition thus possibly being in the totally or partially crosslinked state or in the non-crosslinked state.

The term "elastomeric matrix" means all the elastomers of the composition. In the context of the present invention, the thermoplastic elastomer does not form part of the elastomeric matrix.

The expression "part by weight per hundred parts by weight of elastomer" (or phr) should be understood as meaning, for the purposes of the present invention, the proportion, by weight per hundred parts of elastomeric matrix present in the rubber composition under consideration.

In the present text, unless expressly indicated otherwise, all the percentages (%) indicated are weight percentages (%).

Furthermore, any interval of values denoted by the expression "between a and b" represents the range of values extending from more than a to less than b (i.e. limits a and b excluded), whereas any interval of values denoted by the expression "from a to b" means the range of values extending from a up to b (i.e. including the strict limits a and b). In the present document, when an interval of values is denoted by the expression "from a to b", the interval represented by the expression "between a and b" is also and preferentially denoted.

In the present invention, the term "tyre" is understood to mean a pneumatic or non pneumatic tyre. A pneumatic tyre usually includes two beads intended to come into contact with a rim, a crown composed of at least one crown reinforcement and a tread, two sidewalls, the tyre being reinforced by a carcass reinforcement anchored in the two beads. A non-pneumatic tyre, for its part, usually comprises a base, designed for example for mounting on a rigid rim, a crown reinforcement, ensuring the connection with a tread and a deformable structure, such as spokes, ribs or cells, this structure being placed between the base and the crown. Such non-pneumatic tyres do not necessarily include a sidewall. Non-pneumatic tyres are described for example in documents WO 03/018332 and FR2898077. According to any one of the embodiments of the invention, the tyre according to the invention is preferentially a pneumatic tyre.

The compounds mentioned in the description can be of fossil origin or can be biobased. In the latter case, they may be partially or completely derived from biomass or may be obtained from renewable starting materials derived from biomass. Similarly, the compounds mentioned may also originate from the recycling of already-used materials, i.e. they may partially or totally result from a recycling process, or else be obtained from starting materials which themselves result from a recycling process. Polymers, plasticizers, fillers, and the like, are concerned in particular.

Unless otherwise indicated, all the values of glass transition temperature "Tg" and melting temperature "Tm" described herein are measured in a known manner by DSC (Differential Scanning Calorimetry) according to ASTM standard D3418 (2015).

II- DESCRIPTION OF THE INVENTION II-1 Elastomeric matrix According to the invention, the elastomeric matrix of the rubber article comprises at least 55% by weight of at least one, that is to say one or more, isoprene elastomers having a molar content of 1,4-cis bond of at least 90%, preferably at least 98%.

Advantageously, the isoprene elastomer having a molar content of 1,4-cis bond of at least 90%, preferably at least 98%, is selected from the group consisting of natural rubber, synthetic polyisoprenes and mixtures thereof. Preferably, this isoprene elastomer is natural rubber.

The rubber article composition may comprise a diene elastomer other than the at least one isoprene elastomer having a molar content of 1,4-cis bond of at least 90%, but this is neither mandatory nor preferred.

It should be remembered that "diene elastomer" should be understood as meaning an elastomer which results at least in part (i.e. a homopolymer or a copolymer) from diene monomers (monomers bearing two conjugated or non-conjugated carbon-carbon double bonds). It may be, for example, polybutadiene (BR), butadiene copolymer, isoprene copolymers and a mixture of these diene elastomers.

Advantageously, having a molar content of 1,4-cis bond of at least 90%, preferably natural rubber represents at least 75% by weight, preferably at least 85% by weight, preferably 100% by weight of the elastomeric matrix of the composition. In other words, natural rubber is preferentially the only elastomer in the elastomeric matrix of the composition of the rubber article according to the invention.

11-2 Thermoplastic elastomer According to the invention, the rubber article composition comprises at least one thermoplastic elastomer comprising at least one polyether elastomer block and at least one non-styrene thermoplastic block, the thermoplastic elastomer having a melting temperature, Tm, within a range extending from 130°C to 175°C.

Generally, thermoplastic elastomers (abbreviated to "TPEs") have a structure intermediate between elastomers and thermoplastic polymers. They are block copolymers consisting of rigid thermoplastic blocks connected by flexible elastomer blocks.

For the requirements of the invention, said specific thermoplastic elastomer is a block copolymer comprising at least one elastomer block of polyether type and at least one thermoplastic block of non-styrene type (TPNS). This elastomer is also denoted TPE containing polyether and TPNS blocks in the present description. In the following text, when reference is made to a polyether block, this is therefore an elastomer block predominantly (that is to say to more than 50% by weight, preferably to more than 80% by weight) composed of a polymer resulting from the polymerization of ether-type monomers, and when reference is made to a non-styrene block, this is a block predominantly (that is to say to more than 50% by weight, preferably to more than 80% by weight) composed of a polymer resulting from the polymerization of monomers other than styrene compounds (that is to say styrene and substituted and/or functionalized styrenes).

For the purposes of the invention, the melting temperature (Tm) of the TPE containing polyether and TPNS blocks is within a range extending from 130°C to 175°C. Advantageously, the Tm of the TPE containing polyether and TPNS blocks is within a range extending from 140°C to 170°C, preferably from 150°C to 169°C.

It may be noted that the Tm of the TPE containing polyether and TPNS blocks corresponds to the Tm of the thermoplastic blocks of TPE.

11-2-1 Structure of the TPE containing polyether and TPNS blocks The number-average molecular weight (denoted Mn) of the TPE containing polyether and TPNS blocks is preferably between 30 000 and 500 000 g/mol, more preferably between 40 000 and 400 000 g/mol. Thus, it has been found that a value lying in a range extending from 50 000 to 300 000 g/mol and better still from 60 000 to 150 000 was particularly well suited, in particular to a use of TPE containing polyether and TPNS blocks in a rubber article according to the invention.

The number-average molecular weight (Mn) of the TPE elastomer containing polyether and TPNS blocks is determined, in a known way, by size exclusion chromatography (SEC). For example, in the case of thermoplastic styrene elastomers, the sample is dissolved beforehand in tetrahydrofuran at a concentration of approximately 1 g/l and then the solution is filtered through a filter with a porosity of 0.45 pm before injection. The apparatus used is a Waters Alliance chromatographic line. The elution solvent is tetrahydrofuran, the flow rate is 0.7 ml/min, the temperature of the system is 35°C and the analysis time is 90 min. A set of four Waters columns in series, with the Styragel tradenames (HMW7, HMW6E and two HT6Es), is used. The injected volume of the solution of the polymer sample is 100 pl. The detector is a Waters 2410 differential refractometer and its associated software, for processing the chromatographic data, is the Waters Millennium system. The calculated average molar masses are relative to a calibration curve produced with polystyrene standards. The conditions can be adjusted by those skilled in the art. The value of the polydispersity index PI (reminder: PI = Mw/Mn, with Mw the weight-average molecular weight and Mn the number-average molecular weight) of the TPE containing polyether and TPNS blocks is preferably less than 3, more preferably less than 2 and more preferably still less than 1.5.

The TPE containing polyether and TPNS blocks is provided in a linear form. For example, the TPE containing polyether and TPNS blocks is a diblock copolymer: polyether block/TPNS block. The TPE containing polyether and TPNS blocks can also be a triblock copolymer: polyether block/TPNS block/polyether block, that is to say a central elastomer block and two terminal thermoplastic blocks, at each of the two ends of the elastomer block. Equally, the multiblock TPE containing polyether and TPNS blocks can be a linear series of polyether elastomer blocks/thermoplastic non-styrene blocks.

Alternatively, the TPE containing polyether and TPNS blocks of use for the requirements of the invention can be provided in a star-branched form comprising at least three branches. For example, the TPE containing polyether and TPNS blocks can then be composed of a star-branched polyether elastomer block comprising at least three branches and of a thermoplastic TPNS block located at the end of each of the branches of the polyether elastomer block. The number of branches of the central elastomer can vary, for example from 3 to 12 and preferably from 3 to 6.

Alternatively, the TPE containing polyether and TPNS blocks may be in a branched or dendrimer form. The TPE containing polyether and TPNS blocks can then be composed of a branched or dendrimer polyether elastomer block and of a thermoplastic TPNS block located at the end of the branches of the dendrimer elastomer block.

Preferably, the TPE containing polyether and TPNS blocks is provided in a linear and multiblock form.

The volume fraction of polyether elastomer block in the TPE containing polyether and TPNS blocks is within a range extending from 1% to 95%, preferably from 10% to 92% and more preferentially from 30% to 90%.

The volume fraction of TPNS block in the TPE containing polyether and TPNS blocks is within a range extending from 5% to 99%, preferably from 8% to 90% and more preferably from 10% to 70%.

11-2.2 Elastomer blocks The elastomer blocks of the TPE containing polyether and TPNS blocks for the requirements of the invention can be any elastomer of polyether type known to those skilled in the art.

These polyether blocks preferably have a Tg (glass transition temperature), measured by DSC according to ASTM standard D3418, 1999, of less than 25°C, preferably of less than 10°C, more preferably of less than 0°C and very preferably of less than -10°C. Preferably also, the Tg of the polyether blocks is greater than -100°C. The polyether blocks having a Tg of between -70°C and 20°C and more particularly between -50°C and 0°C are suitable in particular.

For the purposes of the present invention, the polyether blocks can be composed of monomers selected from alcohols or cyclic ethers, preferentially aliphatic alcohols or aliphatic cyclic ethers, such as, for example, ethanol or tetrahydrofuran. The choice will preferably be made, among the polyethers, of those selected from the group consisting of polytetramethylene glycols (PTMGs), polyethylene glycols (PEGs), polypropylene ether glycol (PPG), polyhexamethylene ether glycol, polytrimethylene ether glycol (PO3G), poly(3-alkyltetrahydrofuran) and mixtures thereof. The polyether is very preferably selected from the group consisting of polytetramethylene glycols (PTMGs), polyethylene glycols (PEGs) and mixtures thereof.

The elastomer blocks may further comprise polyester blocks. Among the polyesters, mention may be made of polyethylene terephthalate, polybutene terephthalate and poly(ethylene-2,6-naphthalate), and also polybutylene succinate and polyethylene adipate. These blocks advantageously have a Tg, measured by DSC according to ASTM standard D3418, of2015, of less than 90°C, preferably between -70°C and 20°C and more particularly between -50°C and 0°C.

Advantageously, the elastomer blocks of the TPE containing polyether and TPNS blocks exhibit, in total, a number-average molecular weight ("Mn") ranging from 25 000 g/mol to 350 000 g/mol, preferably from 35 000 g/mol to 250 000 g/mol, so as to confer, on the TPE containing polyether and TPNS blocks, good elastomeric properties and a mechanical strength which is sufficient and compatible with the use in a rubber article according to the invention.

The polyether elastomer block can also consist of several polyether elastomer blocks as defined above.

11-2.3 Thermoplastic blocks The thermoplastic blocks of the TPE containing polyether and TPNS blocks are non styrene blocks, that is to say preferably thermoplastics resulting from the polymerization of any suitable monomer and not comprising styrene monomers or comprising less than 5%.

Preferably, the thermoplastic blocks of the TPE containing polyether and TPNS blocks are blocks selected from polyamide blocks. Very preferentially, the thermoplastic blocks of the TPE containing polyether and TPNS blocks are selected from the group consisting of polyamides of type PA6, PAll PA12, PA4.12, PA4.14, PA4.18, PA6.10, PA6.12, PA6.14, PA6.18, PA9.12, PA10.10, PA10.12, PA10.14, PA10.18 and mixtures thereof; preferably, the thermoplastic blocks of the TPE containing polyether and TPNS blocks are selected from the group consisting of polyamides of type PA6, PAll, PA12 and mixtures thereof.

The TPEs containing polyether blocks and TPNS blocks of specific type in which the non-styrene thermoplastic blocks are polyamides are usually denoted TPE-A or TPA (thermoplastic copolyamide) or else PEBA (copolyether-block-amide), and they are particularly preferred for the requirements of the invention.

According to the invention, the thermoplastic blocks of the TPE containing polyether and TPNS blocks exhibit, in total, a number-average molecular weight ("Mn") ranging from 5 000 g/mol to 150 000 g/mol, so as to confer, on the TPE containing polyether and TPNS blocks, good elastomeric properties and a mechanical strength which is sufficient and compatible with the use in the rubber article according to the invention.

The thermoplastic block can also consist of several thermoplastic blocks as defined above.

11-2.4 Examples of TPE containing polyether and TPNS blocks As examples of commercially available TPE elastomers containing polyether and TPNS blocks, mention may be made of PEBA elastomers of Pebax type, sold by Arkema, for example under the name Pebax 4033 or Pebax 6333, or the Vestamid E products sold by Evonik, for example under the name Vestamid E55 or Vestamid E62.

11-2.5 Amount of TPE containing polyether and TPNS blocks In the composition of the rubber article according to the invention, the amount of TPE elastomer (that is to say the TPE elastomer or elastomers) containing polyether and TPNS blocks is preferably within a range extending from 1 to 40 phr, preferably from 7 to 30 phr, preferably from 11 to 25 phr.

11-3 Reinforcing filler

According to the invention, the composition of the rubber article is based on a filler comprising from 10 to 60 phr of carbon black and from 5 to 30 phr of silica, the carbon black representing from 55% to 95% by weight relative to the total weight of carbon black and silica.

The blacks which can be used in the context of the present invention can be any black conventionally used in tyres or their treads ("tyre-grade" blacks). Among the latter, mention will be made more particularly of the reinforcing carbon blacks of the 100, 200 and 300 series, or the blacks of the 500, 600 or 700 series (ASTM grades), for instance the NI15, N134, N234, N326, N330, N339, N347, N375, N550, N683 and N772 blacks. These carbon blacks can be used in the isolated state, as commercially available, or in any other form, for example as support for some of the rubber additives used. The carbon blacks might, for example, be already incorporated in the diene elastomer, in particular isoprene elastomer, in the form of a masterbatch (see, for example, patent applications WO 97/36724 or WO 99/16600). Mixtures of several carbon blacks can also be used in the prescribed amounts.

Mention may be made, as examples of organic fillers other than carbon blacks, of functionalized polyvinyl organic fillers, such as described in applications WO 2006/069792, WO 2006/069793, WO 2008/003434 and WO 2008/003435.

Advantageously, the BET specific surface area of the carbon black is at least 90m 2 /g, preferably between 100 and 150 m 2 /g. The BET specific surface area of the carbon blacks is measured according to ASTM standard D6556-10 [multipoint (a minimum of 5 points) method - gas: nitrogen - relative pressure p/po range: 0.1 to 0.3].

The carbon black advantageously exhibits a COAN oil absorption number of greater than or equal to 90 ml/100 g. The COAN, or Compressed Oil Absorption Number, of the carbon blacks is measured according to ASTM standard D3493-16.

Advantageously, the content of carbon black (whether there is one or more thereof) in the composition according to the invention is within a range extending from 15 to 55 phr, preferably from 30 to 50 phr.

The silicas that can be used in the context of the present invention can be any silica known to those skilled in the art, in particular any precipitated or fumed silica exhibiting a BET surface area and a CTAB specific surface area which are both less than 450 m 2/g, preferably from 30 to 400 m2 /g. It can also be a mixture of several silicas, as long as they are used in the prescribed amounts.

The BET specific surface area of the silica is determined by gas adsorption using the Brunauer-Emmett-Teller method described in "The Journal of the American Chemical Society" (Vol. 60, page 309, February 1938), and more specifically according to a method adapted from standard NF ISO 5794-1, Appendix E of June 2010 [multipoint (5 point) volumetric method - gas: nitrogen - degassing under vacuum: one hour at 160°C - relative pressure p/po range: 0.05 to 0.17].

The CTAB specific surface area values of the silica were determined according to standard NF ISO 5794-1, Appendix G of June 2010. The process is based on the adsorption of CTAB (N-hexadecyl-N,N,N-trimethylammonium bromide) on the "external" surface of the reinforcing filler.

The silicones that can be used in the context of the present invention advantageously have a BET specific surface area of less than 250 m /g and/or a CTAB specific surface area of 2

less than 220 m /g, preferably a BET specific surface area within a range extending from 2

125 to 200 m /g and/or a CTAB specific surface area within a range extending from 140 2

to 170 m 2/g.

Mention will be made, as silicas that can be used in the context of the present invention, for example, of the highly dispersible precipitated silicas (termed "HDSs") Ultrasil 7000 and Ultrasil 7005 from Evonik, the Zeosil 1165MP, 1135MP and 1115MP silicas from Rhodia, the Hi-Sil EZ150G silica from PPG, the Zeopol 8715, 8745 and 8755 silicas from

Huber or the silicas with a high specific surface area as described in application WO 03/016387.

Advantageously, the content of silica (whether there is one or more thereof) in the composition according to the invention is within a range extending from 5 to 25 phr, preferably from 6 to 20 phr.

In order to couple the reinforcing silica to the diene elastomer, use may be made, in a well-known way, of an at least bifunctional coupling agent (or bonding agent) intended to provide a satisfactory connection, of chemical and/or physical nature, between the silica (surface of its particles) and the diene elastomer (hereinafter simply referred to as "coupling agent"). Use is made in particular of organosilanes or polyorganosiloxanes which are at least bifunctional. The term "bifunctional" is understood to mean a compound having a first functional group capable of interacting with the inorganic filler and a second functional group capable of interacting with the diene elastomer. For example, such a bifunctional compound can comprise a first functional group comprising a silicon atom, said first functional group being capable of interacting with the hydroxyl groups of an inorganic filler, and a second functional group comprising a sulfur atom, said second functional group being capable of interacting with the diene elastomer.

Those skilled in the art can find examples of coupling agents in the following documents: WO 02/083782, WO 02/30939, WO 02/31041, WO 2007/061550, WO 2006/125532, WO 2006/125533, WO 2006/125534, US 6 849 754, WO 99/09036, WO 2006/023815, WO 2007/098080, WO 2010/072685 and WO 2008/055986.

However, it is advantageous in the context of the present invention not to use a coupling agent. Thus, preferentially, the content of coupling agent, in the composition according to the invention, is advantageously less than 6% by weight relative to the weight of silica, preferably less than 2%, preferably less than 1% by weight relative to the weight of silica. More preferably, the composition according to the invention does not comprise coupling agent.

Moreover, when the composition according to the invention comprises silica, the composition advantageously comprises an agent for covering the silica. Among the agents for covering the silica, mention may be made, for example, of hydroxysilanes or hydrolysable silanes such as hydroxysilanes (see, for example, WO 2009/062733), alkylalkoxysilanes, especially alkyltriethoxysilanes such as, for example, 1 octyltriethoxysilane, polyols (for example diols or triols), polyethers (for example polyethylene glycols), primary, secondary or tertiary amines (for example trialkanolamines), an optionally substituted guanidine, especially diphenylguanidine, hydroxylated or hydrolysable polyorganosiloxanes (for example a,o dihydroxypolyorganosilanes (especially a,o-dihydroxypolydimethylsiloxanes) (see, for example, EP 0 784 072)), and fatty acids such as, for example, stearic acid. When an agent for covering the silica is used, it is used at a content of between 0 and 5 phr. Preferably, the agent for covering the silica is a polyethylene glycol. The content of silica covering agent, preferably of polyethylene glycol, in the composition according to the invention is advantageously within a range extending from 1 to 6 phr, preferably from 1.5 to 4 phr.

Advantageously, the total content of carbon black and silica in the composition according to the invention is within a range extending from 15 to 90 phr and preferably from 20 to 70 phr.

Advantageously, the carbon black represents from 60% to 90% by weight, preferably from 65% to 80% by weight, relative to the total weight of carbon black and silica.

11-4 Crosslinking system The crosslinking system may be any type of system known to those skilled in the art in the field of rubber compositions for tyres. It may notably be based on sulfur, and/or peroxide and/or bismaleimides.

Preferentially, the crosslinking system is based on sulfur; it is then called a vulcanization system. The sulfur can be contributed in any form, in particular in the form of molecular sulfur and/or of a sulfur-donating agent. At least one vulcanization accelerator is also preferentially present, and, optionally, also preferentially, use may be made of various known vulcanization activators, such as zinc oxide, stearic acid or equivalent compound, such as stearic acid salts, and salts of transition metals, guanidine derivatives (in particular diphenylguanidine), or else known vulcanization retarders.

The sulfur is used at a content preferably of between 0.5 and 12 phr, in particular between 1 and 10 phr. The vulcanization accelerator is used at a preferential content of between 0.5 and 10 phr, more preferentially of between 0.5 and 5.0 phr.

Use may be made, as accelerator, of any compound capable of acting as accelerator of the vulcanization of diene elastomers in the presence of sulfur, in particular accelerators of the thiazole type, and also their derivatives, or accelerators of sulfenamide, thiuram, dithiocarbamate, dithiophosphate, thiourea and xanthate types. Mention may in particular be made, as examples of such accelerators, of the following compounds: 2 mercaptobenzothiazyl disulfide (abbreviated to "MBTS"), N-cyclohexyl-2 benzothiazolesulfenamide ("CBS"), N,N-dicyclohexyl-2-benzothiazolesulfenamide ("DCBS"), N-(tert-butyl)-2-benzothiazolesulfenamide ("TBBS"), N-(tert-butyl)-2 benzothiazolesulfenimide ("TBSI"), tetrabenzylthiuram disulfide ("TBZTD"), zinc dibenzyldithiocarbamate ("ZBEC") and the mixtures of these compounds.

11-5 Possible additives The compositions of the rubber articles according to the invention may optionally also include all or some of the usual additives customarily used in elastomer compositions for tyres, for instance plasticizers (such as plasticizing oils and/or plasticizing resins), pigments, protective agents such as anti-ozone waxes, chemical anti-ozonants, antioxidants, anti-fatigue agents, reinforcing resins (as described, for example, in patent application WO 02/10269).

11-6 Manufacturing process The compositions of the rubber articles can be manufactured in suitable mixers, using two successive preparation phases well known to those skilled in the art:

- a first phase of thermomechanical working or kneading ("non-productive" phase), that can be performed in a single thermomechanical step during which all the necessary constituents, notably the elastomeric matrix, the reinforcing filler and the optional various other additives, with the exception of the crosslinking system, are introduced into an appropriate mixer, such as a standard internal mixer (for example of Banbury type). The incorporation of the optional filler into the elastomer may be performed in one or more portions while thermomechanically kneading. In the case where the filler is already incorporated, totally or partly, into the elastomer in the form of a masterbatch, as is described, for example, in patent applications WO 97/36724 or WO 99/16600, it is the masterbatch which is directly kneaded and, where appropriate, the other elastomers or fillers present in the composition which are not in masterbatch form, and also the optional various other additives, with the exception of the crosslinking system, are incorporated. The non-productive phase may be performed at high temperature, up to a maximum temperature of between 110°C and 200°C, preferably between 130°C and 185°C, for a period of time generally of between 2 and 10 minutes; - a second phase of mechanical working ("productive" phase), which is performed in an external mixer, such as an open mill, after cooling the mixture obtained during the non productive first phase down to a lower temperature, typically below 120°C, for example between 40°C and 100°C. The crosslinking system is then incorporated and the combined mixture is then mixed for a few minutes, for example between 5 and 15 min.

Such phases have been described, for example, in patent applications EP-A-0501227, EP A-0735088, EP-A-0810258, WO 00/05300 or WO 00/05301.

Advantageously, the composition of the rubber article according to the invention can be prepared according to a process comprising the following steps: (a) bringing into contact and mixing, concomitantly or successively, in one or more batches, at least 55% by weight of the at least one isoprene elastomer having a molar content of 1,4-cis bond of at least 90%, the thermoplastic elastomer comprising at least one polyether elastomer block and at least one non-styrene thermoplastic block having a Tm within a range extending from 130°C to 175°C, 10 to 60 phr of carbon black and 5 to 30 phr of silica, the carbon black representing from 55% to 95% by weight relative to the total weight of carbon black and silica, by thermomechanically kneading the whole until a maximum temperature TI is reached which is greater than or equal to the melting temperature of the thermoplastic elastomer comprising at least one polyether elastomer block and at least one non-styrene thermoplastic block, (b) reducing the temperature of the mixture obtained in step (a) to a maximum temperature T2 below the melting temperature of the thermoplastic elastomer comprising at least one polyether elastomer block and at least one non-styrene thermoplastic block, then incorporating a crosslinking system into the mixture and mixing the whole.

This process can be carried out using two successive phases of preparation according to a general procedure well known to those skilled in the art: step (a) thus constitutes a first phase of thermomechanical working or kneading (sometimes referred to as a "non productive" phase) at high temperature, up to a maximum temperature of between 130°C and 200°C, preferably between 150°C and 180°C, followed by a second phase of mechanical working (sometimes referred to as a "productive" phase) (step (b) of the process) at lower temperature, typically less than 110°C, for example between 60°C and 100°C, during which finishing phase the crosslinking system is incorporated. Such phases have been described, for example, in applications EP 0 501 227 A, EP 0 735 088 A, EP 0 810 258 A, WO 2000/05300 or WO 2000/05301.

Step (a) may preferentially be carried out for 30 seconds to a few minutes. The total duration of this non-productive phase is preferably between 2 and 10 minutes at a temperature.

According to the invention, the maximum temperature TI is preferably at least 1°C, preferably 5°C, higher than the melting temperature ofthe thermoplastic elastomer comprising at least one polyether elastomer block and at least one non-styrene thermoplastic block. Preferably, the maximum temperature TI is from 1°C to 20°C, preferably from 5°C to 20°C, higher than the melting temperature of the thermoplastic elastomer comprising at least one polyether elastomer block and at least one non-styrene thermoplastic block. Also preferably, the temperature TI is maintained for at least 1 minute, preferably at least 2 minutes, for example between 1 and 10 minutes, preferably between 2 and 6 minutes.

The applicant has found that increasing the maximum temperature Ti above the melting temperature of the thermoplastic elastomer comprising at least one polyether elastomer block and at least one non-styrene thermoplastic block makes it possible to further improve the performance compromise, namely resistance to mechanical attack and hysteresis.

The thermoplastic elastomer comprising at least one polyether elastomer block and at least one non-styrene thermoplastic block (the melting temperature of which is within a range extending from 130°C to 175C) may be introduced in the solid state, as sold commercially, or in the liquid state. When the thermoplastic elastomer comprising at least one polyether elastomer block and at least one non-styrene thermoplastic block is introduced in liquid form, it is then necessary to carry out an additional step of heating the thermoplastic elastomer comprising at least one polyether elastomer block and at least one non-styrene thermoplastic block to a temperature higher than its melting temperature, before it is brought into contact with the other constituents of step (a). However, it is preferable to introduce the thermoplastic elastomer comprising at least one polyether elastomer block and at least one non-styrene thermoplastic block in the solid state.

During step (b), after cooling of the mixture obtained in step (a), the crosslinking system, preferably the vulcanization system, is then incorporated, at a temperature below the melting temperature of the thermoplastic elastomer comprising at least one polyether elastomer block and at least one non-styrene thermoplastic block, generally in an external mixer such as an open mill; the combined mixture is then mixed (productive phase) for a few minutes, for example between 5 and 15 min.

Advantageously, the maximum temperature T2 is preferably less than 120°C, preferably less than 100°C, more preferably less than 90°C. Preferably, the maximum temperature T2 is within a range extending from 20°C to 90°C.

The final composition thus obtained is subsequently calendered, for example in the form of a sheet or of a plaque, in particular for laboratory characterization, or also extruded, in order to form, for example, a rubber profiled element used in the manufacture of semi finished products, in order to obtain products such as a tyre tread. These products may then be used for the manufacture of tyres, according to the techniques known to those skilled in the art.

The crosslinking (or curing) for producing the rubber article is performed in a known manner at a temperature generally of between 120°C and 200°C, under pressure, for a sufficient time which may range, for example, between 5 and 300 min, as a function notably of the curing temperature, of the vulcanization system adopted, of the kinetics of crosslinking of the composition under consideration.

11-7 Rubber articles According to the invention, the rubber article is selected from the group consisting of tyres for civil engineering vehicles (preferably tyres for civil engineering vehicles), caterpillar tracks and conveyor belts. A subject of the present invention is therefore tyres for (preferably) civil engineering vehicles, caterpillar tracks and conveyor belts comprising a composition of the rubber article according to the invention or a composition which can be obtained by the process for manufacturing the rubber article according to the invention, as described above.

One particularly preferred subject of the invention is a tyre for (preferably) civil engineering vehicles, the tread of which comprises a composition based on at least: - one elastomeric matrix comprising at least 55% by weight of at least one isoprene elastomer having a molar content of 1,4-cis bond of at least 90%, preferably at least 55% by weight of natural rubber. - one thermoplastic elastomer comprising at least one polyether elastomer block and at least one non-styrene thermoplastic block, the thermoplastic elastomer having a melting temperature, Tm, within a range extending from 130°C to 175°C, preferably from 140°C to 170°C, - 10 to 60 phr of carbon black,

- 5 to 30 phr of silica, and - a crosslinking system, the carbon black representing from 55% to 95% by weight, relative to the total weight of carbon black and silica, the composition being prepared by a process comprising the following steps: (a) bringing into contact and mixing, concomitantly or successively, in one or more batches, at least 55% by weight of the at least one isoprene elastomer having a molar content of 1,4-cis bond of at least 90%, the thermoplastic elastomer comprising at least one polyether elastomer block and at least one non-styrene thermoplastic block having a Tm within a range extending from 130°C to 175°C, 10 to 60 phr of carbon black and 5 to 30 phr of silica, the carbon black representing from 55% to 95% by weight relative to the total weight of carbon black and silica, by thermomechanically kneading the whole until a maximum temperature Ti is reached which is greater than or equal to (preferably 5°C to 20°C greater than) the melting temperature of the thermoplastic elastomer comprising at least one polyether elastomer block and at least one non-styrene thermoplastic block, (b) reducing the temperature of the mixture obtained in step (a) to a maximum temperature T2 below the melting temperature of the thermoplastic elastomer comprising at least one polyether elastomer block and at least one non-styrene thermoplastic block (preferably to a temperature within a range extending from 20°C to 90°C), then incorporating a crosslinking system into the mixture and mixing the whole.

With regard to the tyres for civil engineering vehicles, it may be noted that the tread has a tread surface provided with a tread pattern formed by a plurality of grooves delimiting elements in relief (blocks, ribs) so as to generate edge corners of material and also voids. These grooves represent a volume of voids which, relative to the total volume of the tread (including both the volume of elements in relief and that of all the grooves), is expressed by a percentage denoted, in the present document, by "volumetric void ratio". A volumetric void ratio equal to zero indicates a tread without grooves or voids.

Tyres for civil engineering vehicles are provided with treads which have, in comparison with the thicknesses of the treads of the tyres for light vehicles, in particular for passenger vehicles or vans, great thicknesses of rubber material. Typically the wearing part of the tread of a tyre for heavy-duty vehicles has a thickness of at least 15 mm, that of a civil engineering vehicle at least 30 mm, or even up to 120 mm. Thus, the tread of the tyre according to the invention advantageously has one or more grooves of which the average depth ranges from 15 to 120 mm, preferably 65 to 120 mm.

The tyres for civil engineering vehicles according to the invention can have a diameter ranging from 20 to 63 inches, preferably from 35 to 63 inches.

Moreover, the mean volumetric void ratio over the whole of the tread of the tyre for civil engineering vehicles according to the invention can be within a range extending from 5% to 40%, preferably from 5% to 25%.

The caterpillar tracks according to the invention are rubber caterpillar tracks comprising at least one rubber element, the at least one rubber element being preferably an endless rubber belt or a plurality of rubber pads.

III- EXAMPLES 111-1 Measurements and tests used Dynamic properties The dynamic properties G* and max tan(6) are measured on a viscosity analyser (Metravib VA4000) according to ASTM standard D5992-96. The response of a sample of vulcanized composition (cylindrical test specimen with a thickness of2 mm and a cross section of 79 mm 2 ), subjected to a simple alternating sinusoidal shear stress, at a frequency of 10 Hz, at 100°C, according to ASTM standard D 1349-09, is recorded. A strain amplitude sweep is carried out from 0.1% to 50% (outward cycle) and then from 50% to 0.1% (return cycle). On the return cycle, the value of the loss factor, denoted tan( 6 )max, is recorded.

The hysteresis performance results (tan(6)max at 100C) are expressed as a base 100 percentage relative to the control composition TI. A result greater than 100 indicates an improvement in hysteresis performance, or a decrease in hysteresis.

Caterpillartrack test This test is representative of the resistance to attacks. It consists in running a metal caterpillar track mounted on a pneumatic tyre fitted on a wheel and vehicle, and inflated, on which rubber pads of a given composition are attached, on a track filled with stones, for a certain time. At the end of running, the pads are removed and the number of cuts visible to the naked eye on the surface are counted. The lower the number, the better the attack resistance performance.

To carry out this test, pads of different compositions were manufactured (see Table 1 below) according to the process described in point V-i above. To obtain a pad, the non crosslinked composition obtained in point V-i was calendered to a thickness of 5.5 mm, cut out from slabs (2 of 260x120 mm, 2 of 250x100 mm and 2 of 235x90 mm) that are then stacked in a pyramid. This block of 6 slabs was then inserted into a pyramid-shaped mould with a rectangular base of 260x120 mm and a flat top of 235x90 mm in surface area, and cured at a temperature of 120°C for 300 minutes at a pressure of 180 bar, thus enabling the crosslinking of the composition.

The pads were then mounted on two X-Trackl0 metal caterpillar tracks from the company Caterpillar, which were themselves mounted on two Michelin Xmine D2 12.00R24 tyres on the rear axle of a Scania R410 truck. The tyres were re-cut to support the caterpillar tracks. The tyres were inflated to a pressure of 7 bar and bore a load of 4250 kg per tyre.

The truck ran on a flat track covered with 30/60 size porphyry stones obtained from Sonvoles Murcia, Spain, for 5 hours at a speed of 5 km/h. The density of stones on the track was around 1000 to 1500 stones per square metre.

At the end of the test, the cuts visible at the surface of the pads were counted. The result was averaged on the basis of 6 pads. The attack performance results are expressed as a base 100 percentage relative to the control composition TI. A result greater than 100 indicates an improvement in the resistance to attacks.

Resistance to mechanicalattack/hysteresis compromise The performance compromise between resistance to mechanical attack and hysteresis can be considered to be the arithmetic mean of the base 100 percentages of these two performances.

111-2 Preparation of the compositions In the examples which follow, the rubber compositions were produced as described in point 11-6 above. In particular, the "non-productive" phase was carried out in a 0.4 litre mixer for 8 minutes, for a mean blade speed of 50 revolutions per minute, until a maximum dropping temperature of 165°C was reached. The "productive" phase was carried out in an open mill at 23°C for 5 minutes.

The crosslinking of the composition was performed at a temperature of between 130°C and 200°C, under pressure.

111-3 Tests on rubber compositions The examples presented below are intended to compare the resistance to mechanical attack performance and the hysteresis performance of four compositions in accordance with the present invention (C1 to C4) with two control compositions (Ti and T2).

The control composition TI is a composition normally used in the tyres of civil engineering vehicles for its good wear resistance and for its good hysteretic performance. The control composition T2 is a composition normally used in the tyres of civil engineering vehicles for its good resistance to mechanical attack, to the detriment of hysteresis.

The compositions tested (in phr), as well as the results obtained, are presented in Table 1.

The compositions Cl to C4 differ from the control composition TI by virtue of the presence of a thermoplastic elastomer in accordance with the invention. It may be noted that the filler content was adjusted so that the volume fraction of filler in the composition is constant relative to the control TI. Similarly, the PEG content was adjusted as a function of the silica content, and the thermoplastic elastomer content was adjusted so that its volume fraction in the composition was constant (since Pebax 7033 has a higher density than the other Pebax products used, its amount was reduced accordingly).

[Table 1] TI T2 Cl C2 C3 C4 NR() 100 - 100 100 100 100 SBR(2) - 100 - - -

N115(') 40 - 46 46 46 46 N375(') - 62 - - - Silica(4) 15.3 - 17.5 17.5 17.5 17.5 PEG() 2.5 - 2.9 2.9 2.9 2.9 vol% filler 20% 22% 20% 20% 20% 20% TPE 1(6) - - 17.5 - -

TPE2 7 ) - - - 17.5 TPE 3(8 ) - - - - 17.5 TPE 4(9) - - - - - 17.2 %vol TPE - - 10% 10% 10% 10%

LiquidLiqid- 6 - - -

plasticizer 0 0)

Resin(") - 5 - - -

Antioxidant( 12 ) 1.5 1 1.5 1.5 1.5 1.5 Anti-ozone wax 13 ) 1 - 1 1 1 1 TMQ(1 4) 1 - 1 1 1 1 Stearic acid 1 - 1 1 1 1 ZnO 15 ) 2.7 - 2.7 2.7 2.7 2.7 Accelerator( 16) 1.1 1.1 1.1 1.1 1.1 1.1 Sulfur 1.7 1.3 1.7 1.7 1.7 1.7

Tan(d)max at 100 48 76 72 72 65 100°C

Caterpillar track 100 118 105 174 118 132 test Mean of the 100 83 90.5 123 95 98.5 performances (1) Natural rubber (2) SBR solution, with 5% of 1,2-polybutadiene units, 29% of styrene units - Tg = -52°C (3) Carbon black of N115 or N375 grade according to ASTM standard D-1765 (4) Ultrasil VN3 silica from Evonik (5) Carbowax 8000 polyethylene glycol (6) TPE 1 thermoplastic elastomer Pebax 2533 SA 01 from Arkema (Tm = 134°C) (7) TPE 2 thermoplastic elastomer Pebax 5533 SA 01 from Arkema (Tm = 159°C) (8) TPE 3 thermoplastic elastomer Pebax 55R53 SP 01 from Arkema (Tm = 167°C) (9) TPE 4 thermoplastic elastomer Pebax 7033 SA 01 from Arkema (Tm = 172°C) (10) TDAE oil, Vivatec 500 from Klaus Dahleke (11) Escorez 1102 tackifying resin from EXXON (Mn 1370 g/mol; PDI= 2.3) (12) N-(1,3-Dimethylbutyl)-N-phenyl-para-phenylenediamine, Santoflex 6-PPD from Flexsys (13) Anti-ozone wax, Varazon 4959 from Sasol Wax (14) 2,2,4-Trimethyl-1,2-dihydroquinoline, Pilnox TMQ from Nocil (15) Zinc oxide of industrial grade from Umicore (16) N-Cyclohexyl-2-benzothiazolesulfenamide, Santocure CBS from Flexsys

The results presented in Table 1 above show that the compositions in accordance with the invention make it possible to improve the resistance to mechanical attack compared with the control composition TI, and even compared to the control composition T2, which is a reference control composition with respect to this property, when the melting temperature of the thermoplastic elastomer in accordance with the invention is greater than 140°C. Moreover, the hysteresis performance of the compositions in accordance with the invention is greatly improved compared with the control T2. Thus, the compositions in accordance with the invention exhibit an improvement in the resistance to mechanical attack, without excessively penalizing the performance compromise between resistance to mechanical attack and hysteresis, or even while improving it. These compositions can be used in tyres for civil engineering vehicles, rubber caterpillar tracks and conveyor belts.

Claims (15)

1. Rubber article comprising a composition based on at least: - one elastomeric matrix comprising at least 55% by weight of at least one isoprene elastomer having a molar content of 1,4-cis bond of at least 90%, - one thermoplastic elastomer comprising at least one polyether elastomer block and at least one non-styrene thermoplastic block, the thermoplastic elastomer having a melting temperature, Tm, within a range extending from 130°C to 175°C, - 10 to 60 phr of carbon black, - 5 to 30 phr of silica, and - a crosslinking system, the carbon black representing from 55% to 95% by weight, relative to the total weight of carbon black and silica, the rubber article being selected from the group consisting of tyres for civil engineering vehicles, caterpillar tracks and conveyor belts.

2. Rubber article according to Claim 1, wherein the isoprene elastomer having a molar content of 1,4-cis bond of at least 90% is selected from the group consisting of natural rubber, synthetic polyisoprenes and mixtures thereof; preferably, the isoprene elastomer having a molar content of 1,4-cis bond of at least 90% is natural rubber.

3. Rubber article according to either one of the preceding claims, wherein the isoprene elastomer represents at least 75% by weight, preferably at least 85% by weight, preferably 100% by weight, of the elastomeric matrix of the composition.

4. Rubber article according to any one of the preceding claims, wherein the non-styrene thermoplastic block(s) of the thermoplastic elastomer are selected from the group consisting of polyamides.

5. Rubber article according to any one of the preceding claims, wherein the volume fraction of non-styrene thermoplastic block in the thermoplastic elastomer is within a range extending from 5% to 99%, preferably from 8% to 9 0 %.

6. Rubber article according to any one of the preceding claims, wherein the polyether elastomer block(s) of the thermoplastic elastomer are selected from the group consisting of polytetramethylene glycol (PTMG), polyethylene glycols (PEG), polypropylene ether glycol (PPG), polyhexamethylene ether glycol, polytrimethylene ether glycol (PO3G), poly(3-alkyltetrahydrofuran), and mixtures thereof, preferably from the group consisting of polytetramethylene glycol (PTMG), polyethylene glycols (PEG) and mixtures thereof.

7. Rubber article according to any one of the preceding claims, wherein the thermoplastic elastomer is selected from the group consisting of copolymers containing polyether and polyamide blocks (PEBA).

8. Rubber article according to any one of the preceding claims, wherein the thermoplastic elastomer has a Tm within a range extending from 140°C to 170°C, preferably from 150°C to 169°C.

9. Rubber article according to any one of the preceding claims, wherein the content of the thermoplastic elastomer in the composition is within a range extending from 1 to 40 phr and preferably from 11 to 25 phr.

10. Rubber article according to any one of the preceding claims, wherein the total content of carbon black and silica in the composition is within a range extending from 15 to 90 phr, preferably from 20 to 70 phr.

11. Rubber article according to any one of the preceding claims, wherein the carbon black content in the composition is within a range extending from 15 to 55 phr, preferably from 30 to 50 phr, and the silica content in the composition is within a range extending from 5 to 25 phr, preferably from 6 to 20 phr.

12. Rubber article according to any one of the preceding claims, wherein the carbon black represents from 60% to 90% by weight, preferably from 65% to 80% by weight, relative to the total weight of carbon black and silica.

13. Rubber article according to any one of the preceding claims, wherein the composition does not comprise a coupling agent, or comprises less than 6% by weight thereof relative to the weight of silica, preferably less than 2% by weight thereof relative to the weight of silica.

14. Rubber article according to any one of the preceding claims, wherein the composition is prepared by a process comprising the following steps: (a) bringing into contact and mixing, concomitantly or successively, in one or more batches, at least the at least 55% by weight of the at least one isoprene elastomer having a molar content of 1,4-cis bond of at least 90%, the thermoplastic elastomer comprising at least one polyether elastomer block and at least one non-styrene thermoplastic block having a Tm within a range extending from 130°C to 175°C, 10 to 60 phr of carbon black and 5 to 30 phr of silica, the carbon black representing from 55% to 95% by weight relative to the total weight of carbon black and silica, by thermomechanically kneading the whole until a maximum temperature TI is reached which is greater than or equal to the melting temperature of the thermoplastic elastomer comprising at least one polyether elastomer block and at least one non-styrene thermoplastic block, (b) reducing the temperature of the mixture obtained in step (a) to a maximum temperature T2 below the melting temperature of the thermoplastic elastomer comprising at least one polyether elastomer block and at least one non-styrene thermoplastic block, then incorporating a crosslinking system into the mixture and mixing the whole.

15. Rubber article according to Claim 14, wherein the temperature TI is at least 1C higher, preferably 5°C to 20°C higher, than the temperature ofthe thermoplastic elastomer comprising at least one polyether elastomer block and at least one non- styrene thermoplastic block, and the temperature T2 is less than 100°C, preferably within a range extending from 20°C to 90°C.