CN115427236A

CN115427236A - Rubber composition comprising low-melting polyethylene

Info

Publication number: CN115427236A
Application number: CN202180025033.XA
Authority: CN
Inventors: R·利贝尔; N·韦克尔
Original assignee: Compagnie Generale des Etablissements Michelin SCA
Current assignee: Compagnie Generale des Etablissements Michelin SCA
Priority date: 2020-04-07
Filing date: 2021-04-06
Publication date: 2022-12-02
Anticipated expiration: 2041-04-06
Also published as: FR3108910A1; CA3167814A1; WO2021205108A1; FR3108910B1; BR112022016180A2; AU2021251445A1

Abstract

The invention relates to a rubber composition based on at least one diene elastomer, between 10phr and 60phr of carbon black, between 5phr and 30phr of silica, a polyethylene having a melting point between 120 ℃ and 160 ℃, and a crosslinking system, wherein the carbon black represents between 50% and 95% by weight relative to the total weight of carbon black and silica. The invention also relates to a process for preparing the rubber composition and to a rubber article comprising the composition according to the invention.

Description

Rubber composition comprising low-melting polyethylene

Technical Field

The present invention relates to rubber compositions which exhibit a good compromise of properties between mechanical attack resistance and hysteresis. The present invention is particularly directed to rubber articles such as pneumatic tires, non-pneumatic tires, tracks, conveyor belts, or any other rubber article for which the aforementioned performance compromises are desired.

Background

In particular, the rubber composition of the present invention is very advantageous when used for a tread of a pneumatic tire for civil engineering vehicles. This is because these tires must have very different technical characteristics from tires intended for vehicles running on roads (i.e. bituminous pavements), since the properties of the off-road pavement on which these tires move mainly are very different, in particular more aggressive due to their stone-rich nature. Furthermore, tires for large civil engineering vehicles must be able to withstand loads that can be very heavy, for example compared to passenger car tires. Therefore, the known solutions for tyres intended for running on asphalt cannot be directly applied to off-road tyres, such as tyres for civil engineering vehicles.

During running, the tread is subjected to mechanical stresses and attacks due to direct contact with the ground. In the case of tires mounted to vehicles carrying heavy loads, the mechanical stresses and attacks to which the tires are subjected are amplified by the weight carried by the tires. Tires for mining vehicles are locally subjected to high stresses when travelling on large, dented objects, represented by stones (rubble) forming the track, and are globally subjected to high stresses both in the high torque transmission due to the approximately 10% gradient of the track entering or leaving the "pit" or open pit mine, and in the high stresses on the tires during the U-turn performed by the vehicle for loading and unloading operations.

As a consequence of this, the initial cracks that develop in the tread of the tire under the effect of these stresses and of these attacks have a tendency to propagate further on the surface or inside the tread, which can lead to partial or total tearing of the tread. These stresses can therefore lead to damage to the tread and, therefore, reduce the life of the tread and the life of the tire. Tires that run on rocky ground are highly vulnerable and are therefore susceptible to initial cracking and cuts. The actual nature of the attack on the rocky ground exacerbates not only such attacks on the tread, but also the consequences it has on the tread.

This is particularly true for tires fitted with civil engineering vehicles that are usually moving in mines and quarries. This is also true for tires mounted to agricultural vehicles due to the rocky ground of the arable land. Tires fitted with heavy vehicles on construction sites moving on rocky and bituminous grounds also experience these same attacks. Due to the two aggravating factors of the weight borne by the tire and the aggressiveness of the driving surface, the resistance to crack initiation and/or the growth of the treads of tires for civil engineering vehicles, agricultural vehicles or heavy vehicles on the building site prove to be of vital importance in minimizing the impact of the attacks to which the treads are subjected.

It is therefore important to have a tire usable for vehicles (in particular vehicles intended to run on rocky ground and to carry heavy loads) whose tread exhibits a resistance to crack initiation and/or propagation strong enough to minimize the impact of initial cracks on tread life. To solve this problem, it is known to the person skilled in the art that, for example, natural rubber in the tread makes it possible to obtain improved resistance to crack initiation and/or propagation.

Furthermore, the solution provided to solve this problem is also advantageous in that other properties of the rubber composition are not impaired, in particular hysteresis reflecting the heat dissipating capacity of the composition. This is because the use of a composition that is too late in the tire may cause the increase in the internal temperature of the tire to become significant, which may result in a decrease in the durability of the tire.

In view of the above, it is a continuing object to provide rubber compositions that exhibit an improved compromise between resistance to attack and hysteresis.

This compromise of properties is also advantageous for rubber tracks intended to be mounted to construction vehicles or agricultural vehicles, for the same reasons as described above. It is also advantageous for the conveyor belt (or belt conveyor) to be able to receive a large amount of dirt, ore, stones, rocks and consume a large amount of energy to the material constituting the belt through internal dissipation during the pressing of the belt between its load and the support of the drive belt.

Solutions have been provided to improve this compromise. For example, application WO 2016/202970A1 proposes the use of a specific composition, the elastomer matrix of which comprises a diene elastomer selected from 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 constantly looking for solutions to further improve the performance tradeoff between attack resistance and hysteresis, preferably regardless of the nature of the elastomeric matrix.

In the course of research, the applicant has unexpectedly found that the use of polyethylene having a melting point between 120 ℃ and 160 ℃ enables the above-mentioned property compromise to be improved in the presence of a specific blend of fillers in the rubber composition.

Disclosure of Invention

The subject of the invention is therefore a rubber composition based on at least one diene elastomer, from 10phr to 60phr of carbon black, from 5phr to 30phr of silica, a polyethylene having a melting point of between 120 ℃ and 160 ℃, and a crosslinking system, in which composition the carbon black represents from 50% to 95% by weight relative to the total weight of carbon black and silica.

Another subject of the invention is a rubber article comprising a rubber composition according to the invention, and a pneumatic or non-pneumatic tire whose tread comprises a rubber composition according to the invention.

I-definition of

The expression "composition based on" is understood to mean that the composition comprises a mixture and/or an in situ reaction product of the various components used, some of which are capable of (and/or intended to) at least partially react with each other during the various manufacturing stages of the composition; thus, the composition may be in a fully or partially crosslinked state or in an uncrosslinked state.

For the purposes of the present invention, the expression "phr" is understood to mean parts by weight per hundred parts by weight of elastomer.

Herein, all percentages (%) shown are weight percentages (%), unless explicitly indicated otherwise.

Furthermore, any interval of values denoted by the expression "between a and b" denotes a range of values extending from more than a to less than b (i.e. not including the limits a and b), whereas any interval of values denoted by the expression "from a to b" means a range of values extending from a up to b (i.e. including the strict limits a and b). Herein, when numerical intervals are denoted by the expression "a to b", it is also preferable to denote intervals denoted by the expression "between a to b".

When referring to a "primary" compound, for the purposes of the present invention it is understood to mean that, of the same type of compound in the composition, the compound is primary, that is, it is the compound that makes up the greatest amount by weight of the same type of compound. Thus, for example, the predominant elastomer is the elastomer that makes up the maximum weight based on the total weight of elastomers in the composition. In the same manner, the "predominant" filler is the filler that makes up the greatest weight of the fillers in the composition. For example, in a system comprising only one elastomer, the elastomer is predominant for the purposes of the present invention, whereas in a system comprising two elastomers, the predominant elastomer comprises more than half the weight of the elastomer. In contrast, a "minor" compound is a compound that does not account for the maximum weight parts in the same type of compound. Preferably, the term "primary" is understood to mean present at more than 50%, preferably more than 60%, 70%, 80%, 90%, more preferably the "primary" compound makes up 100%.

The carbon-containing compounds mentioned in the description may be compounds of fossil or bio-based origin. In the case of bio-based sources, they may be partially or completely produced from biomass, or may be obtained from renewable feedstocks derived from biomass. In particular to polymers, plasticizers, fillers, and the like.

All glass transition temperature "Tg" values described herein are measured by DSC (differential scanning calorimetry) in a known manner according to standard ASTM D3418 (1999).

II-description of the invention

II-A composition

II-A-1 elastomer substrates

The composition according to the invention may comprise only one diene elastomer or a mixture of several diene elastomers.

The term "diene" elastomer (or rubber without distinction), whether natural or synthetic, is understood in a known manner to mean an elastomer consisting at least in part (i.e. a homopolymer or a copolymer) of diene monomer units (monomers bearing two conjugated or non-conjugated carbon-carbon double bonds).

These diene elastomers can be divided into two categories: "substantially unsaturated" or "substantially saturated". The term "essentially unsaturated" is generally understood to mean a diene elastomer resulting at least in part from conjugated diene monomers and having a content of units of diene origin (conjugated dienes) which is greater than 15% (mol%); thus diene elastomers such as butyl rubbers or EPDM type copolymers of dienes and of alpha-olefins do not fall within the preceding definition, but can be described in particular as "essentially saturated" diene elastomers (low or very low content of units of diene origin, always less than 15%). Advantageously, the diene elastomer is an essentially unsaturated diene elastomer.

The term "diene elastomer which can be used in the context of the present invention" means in particular:

a) Any homopolymer of a conjugated or non-conjugated diene monomer having from 4 to 18 carbon atoms;

b) Any copolymer of a conjugated or non-conjugated diene having from 4 to 18 carbon atoms with at least one other monomer.

The other monomer may be ethylene, an olefin, or a conjugated or non-conjugated diene.

Suitable conjugated dienes include conjugated dienes containing from 4 to 12 carbon atoms, particularly 1,3-diene (e.g., especially 1,3-butadiene) and isoprene.

Suitable olefins include vinyl aromatic compounds containing from 8 to 20 carbon atoms and aliphatic alpha-monoolefins containing from 3 to 12 carbon atoms.

Suitable vinyl aromatic compounds include, for example, styrene, o-methylstyrene, m-methylstyrene or p-methylstyrene, "vinyltoluene" commercial mixtures or p- (tert-butyl) styrene.

Suitable aliphatic alpha-monoolefins include especially acyclic aliphatic alpha-monoolefins containing from 3 to 18 carbon atoms.

Preferably, the diene elastomer is selected from the group consisting of polybutadiene (BR), synthetic polyisoprene (IR), natural Rubber (NR), butadiene copolymers, isoprene copolymers and mixtures thereof. Preferably, the diene elastomer is selected from the group consisting of synthetic polyisoprenes, natural rubbers and mixtures thereof.

The butadiene copolymer is preferably selected from butadiene/styrene copolymers (SBR). It should be noted that the SBR may be prepared in Emulsion (ESBR) or in solution (SSBR). Whether ESBR or SSBR. Among the copolymers based on styrene and butadiene, in particular SBR, those can be mentioned in particular which have a styrene content of between 5% and 60% by weight, more particularly between 20% and 50% by weight, a content (mol%) of 1,2-linkages of the butadiene fraction of between 4% and 75%, and a content (mol%) of trans-1,4-linkages of between 10% and 80%. Advantageously, the butadiene/styrene copolymer is an SBR made in solution and has a styrene content of between 5% and 60% by weight, preferably between 6% and 30% by weight, relative to the total weight of the copolymer, and a content (mol%) of 1,2-bonds of the butadiene fraction of between 4% and 75%, preferably between 15% and 30%.

Among the isoprene copolymers, mention will in particular be made of isobutylene/isoprene (butyl rubber-IIR), isoprene/Styrene (SIR), isoprene/Butadiene (BIR) or isoprene/butadiene/Styrene (SBIR) copolymers.

Particularly advantageously, the diene elastomer comprises predominantly (preferably exclusively) at least one polyisoprene, preferably at least one epoxidized polyisoprene.

Herein, the term "polyisoprene" means any polyisoprene, whether epoxidized or not. Advantageously, the polyisoprene is a non-epoxidized polyisoprene selected from natural rubber, synthetic polyisoprene and mixtures thereof. Advantageously, the non-epoxidized polyisoprene has a molar content of 1,4-cis bonds of at least 90%.

The term "epoxidized polyisoprene" is intended to mean polyisoprene that has undergone an epoxidation step. The epoxidized polyisoprene may be epoxidized natural rubber, epoxidized synthetic polyisoprene having a molar content of cis-1,4 linkages of at least 90% prior to epoxidation, or mixtures thereof,

the epoxidized polyisoprene used in the context of the present invention is an elastomer and should not be confused with the low molar mass epoxidized polyisoprene (which is not an elastomer due to its low molar mass) typically used as a plasticizer. Epoxidized polyisoprene, which is an elastomer, typically has a high mooney viscosity in the raw state. As an indication, the mooney viscosity at 100 ℃ (ML 1+4) of the epoxidized polyisoprene useful in the context of the present invention is preferably from 30 to 150, more preferably from 40 to 150, even more preferably from 50 to 140.

Mooney viscosity was measured using an oscillating consistometer as described in the standard ASTM D1646 (1999). The measurement is performed according to the following principle: the sample to be analyzed in the raw state, i.e. before curing, is molded (shaped) in a cylindrical chamber heated to a given temperature, e.g. 100 ℃. After 1 minute of preheating, the rotor was rotated at 2 revolutions per minute within the sample, and the working torque for maintaining this motion was measured after 4 minutes of rotation. Mooney viscosity (ML 1+4) is expressed in "mooney units" (MU, 1mu =0.83 newton. Meter).

Epoxidized polyisoprene, whether it be epoxidized natural rubber or epoxidized synthetic polyisoprene, can be obtained in a known manner by epoxidizing polyisoprene, for example by a process based on chlorohydrin or bromohydrin or a process based on hydroperoxide, alkylhydroperoxide or peracid, such as peracetic acid or performic acid. Epoxidized polyisoprenes are commercially available. The degree of molar epoxidation (information provided by the supplier) corresponds to the number of moles of isoprene units epoxidized and in the polyisoprene before epoxidationThe ratio of the number of moles of isoprene units. "degree of epoxidation," expressed in mole percent (mol%), is intended to mean the number of moles of epoxidized cis-1,4-polyisoprene units present in a rubber polymer per 100 moles of total monomer units in the same polymer. In particular by ¹ H NMR analysis to measure the degree of epoxidation.

As examples of commercially available epoxidized polyisoprenes, mention may be made of Epoxyprene 25 and Epoxyprene 50 from Guthrie or Ekoprena 25 and Ekoprena 50 from Felda.

According to the invention, the expression "at least one epoxidized polyisoprene" is understood to mean one or more epoxidized polyisoprenes which may differ in microstructure, macrostructure or degree of epoxidation. Where the polyisoprene comprises a plurality of epoxidized polyisoprenes, the amount of epoxidized polyisoprene referred to in the polyisoprene is suitable for the total weight of the epoxidized polyisoprene in the polyisoprene. For example, in the case of a mixture of epoxidized polyisoprenes, the feature that the epoxidized polyisoprene is present in the rubber composition in a content of greater than 50phr means that the total weight of the epoxidized polyisoprene is greater than 50phr.

In the case where the epoxidized polyisoprene is a mixture of epoxidized polyisoprenes whose molar epoxidation degrees may differ from one another, the mentioned molar epoxidation degrees (whether preferred or not) apply to each epoxidized polyisoprene in the mixture.

According to the invention, the at least one epoxidized polyisoprene advantageously has a molar epoxidation degree ranging from 5% to 85%, preferably from 10% to less than 80%, preferably from 15% to 75%. Advantageously, the molar epoxidation degree of the at least one epoxidized polyisoprene may be in the range from 40% to 80%, preferably from 45% to 75%. Such a degree of epoxidation is particularly advantageous for improving the reinforcement of the rubber composition. Alternatively, the molar epoxidation degree of the at least one epoxidized polyisoprene may be in the range of from 10% to less than 49%, preferably from 15% to less than 40%.

In the compositions according to the invention, the content of diene elastomer, preferably polyisoprene, preferably epoxidized polyisoprene, ranges from 50phr to 100phr, preferably from 75phr to 100 phr; more preferably 100phr.

II-A-2 Filler

According to the invention, the composition is based on a filler comprising 10phr to 60phr of carbon black and 5phr to 30phr of silica, the carbon black representing 50% to 95% by weight relative to the total weight of carbon black and silica.

The carbon black useful in the context of the present invention may be any carbon black conventionally used in pneumatic or non-pneumatic tires or treads therefor ("tire grade" carbon black). In the latter, mention will be made more particularly of reinforcing blacks of the series 100, 200 and 300, or blacks of the series 500, 600 or 700 (ASTM grades), such as the blacks N115, N134, N234, N326, N330, N339, N347, N375, N550, N683 and N772. These carbon blacks may be used in a separate state, as is commercially available, or in any other form, for example as a carrier for some of the rubber additives used. The carbon black may, for example, have been incorporated into diene elastomers, in particular isoprene elastomers, in the form of a masterbatch (see, for example, applications WO 97/36724 or WO 99/16600). Mixtures of several carbon blacks may also be used in the amounts specified.

As examples of organic fillers other than carbon black, mention may be made of functionalized polyvinyl organic fillers such as those described in applications WO2006/069792, WO 2006/069793, WO 2008/003434 and WO 2008/003435.

Advantageously, the carbon black has a BET specific surface area of at least 90m ² In g, preferably in the range of 100m ² G to 150m ² Between/g. According to standard astm d6556-10[ multipoint (minimum 5 points) method-gas: nitrogen-relative pressure p/p ₀ The range is as follows: 0.1 to 0.3]The BET specific surface area of the carbon black was measured.

The carbon black advantageously exhibits a COAN oil absorption value greater than or equal to 90ml/100 g. The COAN or the compression oil absorption value of the carbon black is measured according to the standard ASTM D3493-16.

Advantageously, in the composition according to the invention, the content of carbon black, whether one or more is present, is in the range from 15phr to 55phr, preferably from 30phr to 50phr.

The silica which can be used in the context of the present invention may be any silica known to the person skilled in the art, in particular having a BET surface area and a CTAB specific surface area both of which are less than 450m ² A ratio of/g, preferably 30m ² G to 400m ² (ii) any precipitated silica or fumed silica per gram. It may also be a mixture of several silicas, as long as they are used in the specified amounts.

The BET specific surface area of The silica was determined by gas adsorption using The Brunauer-Emmett-Teller method described in "The Journal of The American Chemical Society" (Vol.60, p.309, 2.1938), more specifically according to The method of Standard NF ISO 5794-1 (appendix E) at 6.2010 [ multipoint (5 points) volume method-gas: nitrogen-vacuum degassing: 1 hour at 160 ℃ relative pressure p/p ₀ The range is as follows: 0.05 to 0.17]The BET specific surface area of the silica was measured.

The CTAB specific surface area value of the silica was determined according to standard NF ISO 5794-1 (appendix G) at 6 months 2010. The method is based on the adsorption of CTAB (N-hexadecyl-N, N-trimethylammonium bromide) on the "external" surface of the reinforcing filler.

The silicas which can be used in the context of the present invention advantageously have a particle size of less than 250m ² BET specific surface area/g and/or less than 220m ² CTAB specific surface area/g, preferably BET specific surface area of 125m ² G to 200m ² In the range of/g and/or a CTAB specific surface area of 140m ² G to 170m ² In the range of/g.

As silicas which can be used in the context of the present invention, mention will be made, for example, of the highly dispersible precipitated silicas (the term "HDS") Ultrasil 7000 and Ultrasil 7005 from Evonik, the silicas Zeosil 1165MP, 1135MP and 1115MP from Rhodia, the silica Hi-Sil EZ150G from PPG, the silicas Zeopol 8715, 8745 and 8755 from Huber or the silicas with a high specific surface area as described in application WO 03/016387.

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

For coupling the reinforcing silica to the diene elastomer, an at least bifunctional coupling agent (or binder) (hereinafter simply referred to as "coupling agent") aimed at providing satisfactory chemical and/or physical linkage between the silica (its particle surface) and the diene elastomer may be used in a known manner. In particular, at least bifunctional organosilanes or polyorganosiloxanes are used. The term "bifunctional" is understood to mean that the compound has 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 may comprise a first functional group containing a silicon atom, capable of interacting with the hydroxyl groups of the inorganic filler, and a second functional group containing a sulfur atom, capable of interacting with the diene elastomer.

Examples of coupling agents can be found by those skilled in the art in the following references: 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. Preferably, therefore, in the composition according to the invention, the content of coupling agent is advantageously less than 6% by weight, preferably less than 2% by weight, relative to the weight of silica, preferably less than 1% by weight, relative to the weight of silica. More preferably, the composition according to the invention does not comprise a coupling agent.

Furthermore, when the composition according to the invention comprises silica, the composition advantageously comprises a silica covering agent. Among the covering agents for silica, mention may be made, for example, of hydroxysilanes or hydrolysable silanes, such as hydroxysilanes (see, for example, WO 2009/062733), alkylalkoxysilanes, in particular alkyltriethoxysilanes (for example, 1-octyltriethoxysilane), polyols (for example, diols or triols), polyethers (for example, polyethylene glycol), primary, secondary or tertiary amines (for example, trialkanolamines), optionally substituted guanidines, in particular diphenylguanidines, hydroxylated or hydrolysable polyorganosiloxanes (for example, α, ω -dihydroxypolyorganosiloxanes (in particular, α, ω -dihydroxypolydimethylsiloxanes)) (see, for example, EP 0 784 072), and fatty acids, for example stearic acid. When a silica covering agent is used, it is used in a content of between 0 and 5 phr. Preferably, the silica capping agent is polyethylene glycol. In the compositions according to the invention, the content of silica covering agent, preferably polyethylene glycol, is advantageously in the range from 1phr to 6phr, preferably from 1.5phr to 4 phr.

Advantageously, in the composition according to the invention, the total content of carbon black and silica ranges from 15phr to 90phr, preferably from 20phr 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.

The composition according to the invention also has the following essential characteristics: comprising a polyethylene having a melting point between 120 ℃ and 160 ℃, hereinafter referred to as "polyethylene" for the sake of simplifying the expression. Melting points were measured by DSC according to standard ASTM D3418 (2015) in a known manner.

The term "polyethylene" means a polymer comprising predominantly ethylene units. Preferably, the polyethylene (i.e. a polyethylene having a melting point between 120 ℃ and 160 ℃) comprises more than 50 mol%, preferably more than 75 mol%, more preferably more than 90 mol% of ethylene units.

Advantageously, the polyethylene comprises no polypropylene units or less than 10% by weight of polypropylene units relative to the total weight of the polyethylene. Preferably, the polyethylene does not comprise polypropylene units.

Advantageously, the polyethylene is chosen from high density polyethylene, low density polyethylene, linear low density polyethylene, medium density polyethylene, very high molecular weight polyethylene, very low density polyethylene and mixtures of these polyethylenes.

Preferably, the polyethylene has a density of 910kg/m ³ To 970kg/m ³ More preferably 940kg/m ³ To 965kg/m ³ Within the range of (1).

Preferably, the melt flow index of the polyethylene at 190 ℃ under 2.16kg is in the range of 0.1g/10min to 25g/10min, preferably in the range of 1g/10min to 15g/10 min. The melt flow index can be measured according to standard ISO 1133.

The polyethylene may be a functionalized polyethylene comprising at least one functional group comprising at least one heteroatom selected from Si, N, O, S and Cl.

Advantageously, when the polyethylene is functionalized, it is a polyethylene functionalized with a function selected from maleic anhydride functions, epoxy functions, amine functions and acid functions, preferably a polyethylene functionalized with maleic anhydride functions.

The content of polyethylene having a melting point between 120 ℃ and 160 ℃ may range from 3phr to 40phr, preferably from 5phr to 30 phr.

Advantageously, the total content of carbon black, silica and polyethylene having a melting point between 120 ℃ and 160 ℃ is in the range from 20phr to 90phr, preferably from 30phr to 80 phr.

It is also advantageous that the volume fraction of the combination of carbon black, silica and polyethylene is in the range of 10% to 40%, preferably 15% to 35%.

Advantageously, the total content of thermoplastic polymers (i.e. the sum of the thermoplastic polymers comprising polyethylene) is in the range from 3phr to 40phr, preferably from 5phr to 30 phr. It is particularly advantageous that the composition does not comprise a thermoplastic polymer other than polyethylene having a melting point between 120 ℃ and 160 ℃.

The polyethylenes which can be used can be obtained by known conventional processes, such as, in particular, polymerization in the presence of metallocene catalysts. At the end of the polymerization, the polyethylene is pelletized without any crosslinking reaction. Non-functionalized and non-crosslinked polyethylenes are commercially available from suppliers such as Dow Global Technologies, exxonMobil, silon or ENI.

Mention may be made, as examples of polyethylene commercially available, of the Eraclene MP90U polyethylene from ENI or the B5206 polyethylene from Sabic, and, as examples of functionalized polyethylene, the Exxelor from ExxonMobil ^TM PE 1040 or Orevac18302 from Arkema.

II-A-3 crosslinking system

The crosslinking system may be any type of system known to those skilled in the art of tire rubber compositions. The crosslinking system may in particular be based on sulfur and/or peroxide and/or bismaleimides.

Preferably, the crosslinking system is based on sulfur; the crosslinked system is referred to as a cure system. The sulphur may be provided in any form, in particular as molecular sulphur and/or as a sulphur donor. Also preferably present is at least one vulcanization accelerator, and optionally, also preferably, various known vulcanization activators such as zinc oxide, stearic acid or equivalent compounds (e.g., stearates), and salts of transition metals, guanidine derivatives (especially diphenylguanidine), or known vulcanization retarders may be used.

Sulfur is used in a preferred amount of between 0.5phr and 12phr, in particular between 1phr and 10 phr. The vulcanization accelerator is used in a preferred amount of between 0.5phr and 10phr, more preferably between 0.5phr and 5.0 phr.

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

II-A-4 possible additives

The rubber composition may also optionally comprise all or some of the usual additives commonly used in tyre elastomer compositions, such as plasticizers (for example plasticizing oils and/or plasticizing resins), pigments, protective agents (for example antiozone waxes, chemical antiozonants, antioxidants), antifatigue agents, reinforcing resins (for example reinforcing resins described in application WO 02/10269). The composition according to the invention may also preferably not comprise certain ingredients which may impair the properties of the composition. Advantageously, the composition according to the invention does not comprise a foaming agent which would impair the durability of the composition, reduce the resistance of the composition to attack, etc.

II-B preparation method

The subject of the invention is also a process for preparing a rubber composition according to the invention, characterized in that it comprises the following steps:

a) Simultaneously or sequentially contacting and mixing at least one diene elastomer, a filler comprising carbon black and silica (carbon black representing from 50% to 95% by weight relative to the total weight of carbon black and silica), and a polyethylene having a melting point between 120 ℃ and 160 ℃ in one or more portions, thermomechanically kneading all the substances until a maximum temperature T1 is reached, said maximum temperature T1 being greater than or equal to the melting point of the polyethylene,

b) Reducing the temperature of the mixture obtained in step (a) to a maximum temperature T2, said maximum temperature T2 being less than the melting point of the polyethylene; the crosslinking system is then incorporated into the mixture and the entire resulting mixture is kneaded.

In a general embodiment, and advantageously in a preferred embodiment, the nature and content of the diene elastomer, of the carbon black, of the silica, of the optional coupling agent, of the polyethylene having a melting point of between 120 ℃ and 160 ℃ and of the crosslinking system are as defined above for point II-A.

The process according to the invention can be carried out using two successive preparation stages according to general procedures known to those skilled in the art: step (a) thus constitutes a first stage (sometimes called "non-preparation" stage) of thermomechanical working or kneading at high temperatures (up to a maximum temperature between 130 ℃ and 190 ℃, preferably between 140 ℃ and 180 ℃), followed by a second stage (sometimes called "preparation" stage) of mechanical working at lower temperatures (generally less than 110 ℃, for example between 60 ℃ and 100 ℃) (step (b) of the process according to the invention), incorporating the crosslinking system during the finishing stage. Such stages have been described, for example, in the applications EP 0501227A, EP 0735088A, EP 0810258A, WO 2000/05300 or WO 2000/05301.

Preferably, the first (non-preparation) stage may be performed in a plurality of thermomechanical steps. During the first step, at least one diene elastomer, at least one polyethylene having a melting point of between 120 ℃ and 160 ℃, at least one carbon black and at least one silica are introduced into a suitable mixer (for example a conventional internal mixer) at a temperature of between 20 ℃ and 100 ℃, preferably between 25 ℃ and 100 ℃. After several minutes (preferably from 0.5min to 2 min) and the temperature has risen to 90 ℃ to 100 ℃, the other ingredients than the crosslinking system (i.e. those remaining if not all were introduced at the outset) may be added all at once or in portions during the mixing process for 20 seconds to several minutes. In this non-preparation phase, the total duration of kneading at a temperature of less than or equal to 180 ℃, preferably less than or equal to 170 ℃, is preferably between 2 minutes and 10 minutes.

After cooling the mixture thus obtained, the crosslinking system (preferably the vulcanization system) is then incorporated, usually in an open mixer (for example an open mill), at low temperature (usually less than 100 ℃); the combined mixture is then mixed (preparation phase) for several minutes, for example between 5 and 15 minutes.

The final composition thus obtained is then calendered, for example in the form of a sheet or plate (in particular for laboratory characterization), or extruded to form a rubber profiled element, for example for the manufacture of semi-finished products, to obtain a product such as a tire tread. These products can then be used to manufacture tyres according to techniques known to those skilled in the art.

The crosslinking (or curing) is carried out in a known manner at a temperature generally between 100 ℃ and 200 ℃ (for example between 130 ℃ and 200 ℃) and under pressure for a sufficient time which may vary, for example, between 5 minutes and 90 minutes, in particular as a function of the curing temperature, of the vulcanization system employed, of the crosslinking kinetics of the composition under consideration. Preferably, the crosslinking is carried out at a temperature between 110 ℃ and 160 ℃, preferably between 120 ℃ and 150 ℃.

The polyethylene (melting point between 120 ℃ and 160 ℃) can be introduced in a solid state (as is commercially available) or in a liquid state. When introducing the polyethylene in liquid form, then an additional step of heating the polyethylene to a temperature above its melting point must be carried out before contacting the polyethylene with the other components of step (a). However, it is preferred to incorporate the polyethylene in the solid state.

According to the invention, the maximum temperature T1 is preferably at least 1 ℃, preferably 2 ℃, preferably 3 ℃, preferably 4 ℃, preferably 5 ℃ higher than the temperature of the polyethylene. Preferably, the maximum temperature T1 is from 5 ℃ to 20 ℃ higher than the temperature of the polyethylene.

According to the invention, the maximum temperature T2 is preferably less than 120 ℃, preferably less than 100 ℃ and more preferably less than 90 ℃. Preferably, the maximum temperature T2 is in the range of 20 ℃ to 90 ℃.

II-C composition obtainable by the process according to the invention and tire

The subject of the invention is also a rubber composition obtainable by the process according to the invention.

II-D rubber product

The subject of the invention is also a rubber article comprising a composition according to the invention or comprising a composition obtainable by a process according to the invention.

In view of the improved performance compromise within the context of the present invention, the rubber article is advantageously selected from pneumatic tires, non-pneumatic tires, tracks and conveyor belts.

More particularly, the subject of the invention is also a pneumatic or non-pneumatic tire, the tread of which comprises a composition according to the invention or a composition obtainable by a method according to the invention.

The tread surface of the tread is provided with a tread pattern formed by a plurality of grooves delimiting relief elements (tread blocks, ribs) forming edge corners and voids of material. These grooves exhibit a void volume expressed in percent with respect to the total volume of the tread (including the volume of the relief elements and the volume of all the grooves), herein denoted as "volumetric void ratio". A volumetric void ratio equal to zero means that the tread has no grooves or voids.

The invention applies in particular to the treads of tires intended for civil engineering or agricultural vehicles and heavy vehicles, more particularly civil engineering vehicles, the tires of which are subjected to highly specific stresses, in particular the tires driving over rocky ground. Thus, advantageously, a pneumatic or non-pneumatic tire whose tread comprises a composition according to the invention or a composition obtainable by a process according to the invention is a tire for a civil engineering vehicle, an agricultural vehicle or a heavy vehicle, preferably a civil engineering vehicle. These tires have treads of a very thick rubber material, compared to the tread thickness of tires for light vehicles, in particular passenger cars or trucks. Typically, the thickness of the tread wear portion of a tyre for heavy vehicles is at least 15mm, the thickness of the tread wear portion of a tyre for civil engineering vehicles is at least 30mm, or even up to 120mm. The tread of the tire according to the invention therefore advantageously has one or more grooves having an average depth in the range 15mm to 120mm, preferably 65mm to 120mm.

The pneumatic tire according to the present invention may have a diameter ranging from 20 inches to 63 inches, preferably from 35 inches to 63 inches.

Furthermore, the average volumetric void ratio of the entire tread of the tire according to the invention may be in the range of 5% to 40%, preferably 5% to 25%.

The subject of the invention is also a rubber track comprising at least one rubber element comprising a composition according to the invention or comprising a composition obtainable by a process according to the invention, preferably an endless rubber belt or a plurality of rubber mats, and a rubber conveyor belt comprising a composition according to the invention or comprising a composition obtainable by a process according to the invention.

The present invention relates to a tyre in the green state (i.e. before curing) and in the cured state (i.e. after cross-linking or vulcanisation) and to semi-finished, rubber-made articles for said tyre.

III-preferred embodiments

In summary, preferred embodiments of the present invention are described as follows:

1. rubber composition based on at least one diene elastomer, 10 to 60phr of carbon black, 5 to 30phr of silica, a polyethylene having a melting point of between 120 and 160 ℃, and a crosslinking system, in which composition the carbon black represents from 50 to 95% by weight relative to the total weight of carbon black and silica.

2. The rubber composition according to embodiment 1, wherein the diene elastomer is selected from the group consisting of polybutadiene, synthetic polyisoprene, natural rubber, butadiene copolymers, isoprene copolymers and mixtures of these elastomers, preferably from the group consisting of synthetic polyisoprene, natural rubber and mixtures thereof.

3. The composition according to embodiment 1, wherein the diene elastomer essentially comprises at least one polyisoprene, preferably at least one epoxidized polyisoprene.

4. The composition of embodiment 1, wherein the diene elastomer consists essentially of at least one epoxidized polyisoprene having a molar epoxidation degree ranging from 5% to 85%.

5. The composition according to embodiment 4, wherein the at least one epoxidized polyisoprene has a molar epoxidation degree ranging from 40% to 80%, preferably from 45% to 75%.

6. The composition according to embodiment 4, wherein the at least one epoxidized polyisoprene has a molar epoxidation degree ranging from 10% to less than 49%, preferably from 15% to less than 40%.

7. The composition according to any of embodiments 4 to 6, wherein the Mooney viscosity at 100 ℃ (ML 1+4) of the epoxidized polyisoprene, measured according to standard ASTM D1646 (1999), is in the range of 30 to 150, preferably 40 to 150, more preferably 50 to 140.

8. The composition according to any one of embodiments 3 to 7, wherein the content of polyisoprene, preferably epoxidized polyisoprene, is in the range from 50phr to 100phr, preferably from 75phr to 100 phr; more preferably 100phr.

9. The composition of any of the preceding embodiments, wherein the carbon black is present in an amount ranging from 15phr to 55phr, preferably from 30phr to 50phr.

10. The composition of any of the preceding embodiments, wherein the silica is present in an amount ranging from 5phr to 25phr, preferably from 6phr to 20 phr.

11. The composition according to any one of the preceding embodiments, which comprises no coupling agent, or comprises less than 6% by weight of coupling agent relative to the weight of silica, preferably less than 2% by weight of coupling agent relative to the weight of silica.

12. The composition of any of the preceding embodiments, which does not comprise a coupling agent.

13. The composition of any of the preceding embodiments, wherein the total content of carbon black and silica is in the range of 15phr to 90phr, preferably 20phr to 70 phr.

14. The composition according to any one of the preceding embodiments, wherein 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.

15. The composition according to any one of the preceding embodiments, wherein the polyethylene is functionalized with a functional group selected from maleic anhydride functional groups, epoxy functional groups, amine functional groups and acid functional groups, preferably with maleic anhydride functional groups.

16. The composition of any of the preceding embodiments, wherein the polyethylene comprises no polypropylene units or less than 10 wt% polypropylene units relative to the total weight of the polyethylene.

17. The composition of any of the preceding embodiments, wherein the content of polyethylene having a melting point between 120 ℃ and 160 ℃ is in the range of 3phr to 40phr, preferably 5phr to 30 phr.

18. The composition according to any one of the preceding embodiments, wherein the total content of carbon black, silica and polyethylene having a melting point between 120 ℃ and 160 ℃ is in the range of from 20phr to 90phr, preferably from 30phr to 80 phr.

19. The composition of any of the preceding embodiments, wherein the volume fraction of the combination of carbon black, silica and polyethylene is in the range of 10% to 40%, preferably 15% to 35%.

20. The composition of any of the preceding embodiments, wherein the total content of thermoplastic polymer is in the range of 3phr to 40phr, preferably 5phr to 30 phr.

21. The composition of any of the preceding embodiments, wherein the composition does not comprise a thermoplastic polymer other than polyethylene having a melting point between 120 ℃ and 160 ℃.

22. A process for preparing a composition according to any one of embodiments 1 to 21, characterized in that it comprises the following steps:

b) The temperature of the mixture obtained in step (a) is lowered to a maximum temperature T2, said maximum temperature T2 being less than the melting point of the polyethylene, then the crosslinking system is incorporated into the mixture and the whole of the resulting mixture is kneaded.

23. The method of embodiment 22, wherein the polyethylene is introduced in a solid state.

24. The process according to embodiment 22 or 23, wherein the maximum temperature T1 is from 5 ℃ to 20 ℃ higher than the temperature of the polyethylene.

25. The process according to any one of embodiments 22 to 24, wherein the maximum temperature T2 is less than 120 ℃, preferably less than 100 ℃.

26. A rubber composition obtainable by the method according to any one of embodiments 22 to 25.

27. A rubber article comprising the composition as defined in any one of embodiments 1 to 21 or 26.

28. The rubber article of embodiment 27, said article selected from the group consisting of a pneumatic tire, a non-pneumatic tire, a track, and a conveyor belt.

29. A pneumatic tire or a non-pneumatic tire, the tread of which comprises a composition as defined in any one of embodiments 1 to 21 or 26.

30. The tire according to embodiment 29, which is a tire for a civil engineering vehicle, an agricultural vehicle or a heavy vehicle, preferably a civil engineering vehicle.

31. The tire of embodiment 29 or 30, having a tread with one or more grooves having an average depth in the range of 30mm to 120mm, preferably 45mm to 75 mm.

32. The tire of any one of embodiments 29 to 31, wherein it has an average volumetric void ratio across the tread in the range of 5% to 40%, preferably 5% to 25%.

33. The tire of any one of embodiments 29 to 32, having a diameter in the range of 20 inches to 63 inches, preferably 35 inches to 63 inches.

34. A track comprising at least one rubber element comprising a composition as defined in any of embodiments 1 to 21 or 26.

35. The track of embodiment 34, wherein the at least one rubber element is an endless rubber belt or a plurality of rubber pads.

36. A rubber conveyor belt comprising a composition as defined in any one of embodiments 1 to 21 or 26.

Detailed Description

IV-examples

Measurement and test used for IV-1

Dynamic properties

Measured on a viscosity Analyzer (Metravib VA 4000) according to the standard ASTM D5992-96Kinetic properties G and tan (δ) max. Samples of the vulcanized composition (thickness 2mm and cross-sectional area 79 mm) subjected to a simple alternating sinusoidal shear stress at a frequency of 10Hz were recorded under standard temperature conditions (23 ℃) in accordance with the standard ASTM D1349-09 ² Cylindrical sample of (d). The strain amplitude sweep was performed from 0.1% to 50% (outward cycle), followed by 50% to 0.1% (return cycle). On the return cycle, the value of the loss factor, denoted tan (δ) max, is recorded.

The hysteresis performance results (tan (. Delta.) max at 23 ℃) are expressed as a percentage base 100 relative to the control composition T1. Results above 100 indicate improved hysteresis or reduced hysteresis.

Track testing

This test represents resistance to attack. It consists in running a metal track (a rubber pad of given composition attached to said track) mounted on a pneumatic tire mounted on wheels and vehicles and inflated, on a rail paved with stones, for a certain period of time. At the end of the run, the pad was removed and the number of cuts visible to the naked eye on the surface was counted. The smaller the number, the better the attack resistance.

To perform this test, pads of different compositions were made according to the method described above at point V-1 (see table 1 below). To obtain a mat, the non-crosslinked composition obtained in point V-1 was calendered to a thickness of 5.5mm, cut into sheets (2 260x120 mm, 2 250x100 mm and 2 235x90 mm), and then stacked into a cone. The 6 slab blocks were then inserted into a cone-type mold having a rectangular base of 260x120 mm and a flat top area of 235x90 mm and cured at a temperature of 120 ℃ and a pressure of 180 bar for 300 minutes, thereby causing the composition to crosslink.

The pads were then mounted on two X-Track10 metal tracks from Caterpillar, which were themselves mounted on two Michelin Xmine D212.00R24 tires on the rear axle of a Scania R410 truck. The tire is re-cut to support the track. The tires were inflated to a pressure of 7 bar, each tire bearing a load of 4250 kg.

The truck was driven at 5km/h for 5 hours on a flat track paved with 30/60 size porphyry pebbles obtained from Sonvoles Murcia, spain. The stone density on the track is about 1000 to 1500 stones per square meter.

At the end of the test, the number of cuts visible on the pad surface was counted. The results were averaged on a 6 pad basis. Challenge performance results are expressed as a percentage basis of 100 relative to control composition T1. Results above 100 indicate improved resistance to attack.

Preparation of IV-2 composition

In the following examples, rubber compositions were prepared as described above in points II-B. In particular, the "non-preparation" phase is carried out in a 0.4 liter mixer for 8 minutes, with an average blade speed of 50 revolutions per minute, until a maximum discharge temperature of 165 ℃ is reached. The "preparation" phase is carried out in an open mill at 23 ℃ for 5 minutes.

The crosslinking of the composition is carried out under pressure at a temperature between 130 ℃ and 200 ℃.

IV-3 testing of the rubber composition

The examples given below are intended to compare the performance compromise between mechanical attack resistance and hysteresis of four compositions according to the invention (C1 to C3) with two control compositions (T1 and T2).

The formulations tested each contained an elastomer matrix and a filler system (the properties and contents of which are listed in Table 1 below), and also 1phr of an ozone-resistant Wax (Variazon 4959 from Sasol Wax), 1.5phr of an antioxidant (N-1,3-dimethylbutyl-N-phenyl-p-phenylenediamine, santoflex 6-PPD from Flexsys), 1phr of stearic acid (Pristerene 4931 from Uniqema), 2.5phr of technical zinc oxide (Umicore), 1phr of 2,2,4-trimethyl-1,2-dihydroquinoline (Pilnox TMQ from Nocil) and 2.5phr of Carbowax 8000 polyethylene glycol from Dow Corning, 1.5phr of sulfur and 1.1phr of N-cyclohexyl-2-benzothiazolesulfenamide (Santocure S from Flexsys) as vulcanization accelerators. The properties of these formulations are also listed in table 1 below.

Control T1 is a composition conventionally used for treads for tires for civil engineering vehicles.

Compositions C1 and C2 differ from control T2 only in the presence of polyethylene having a melting point between 120 ℃ and 160 ℃. Composition C3 makes it possible to study the effect of the properties of the diene elastomer on the above-mentioned property compromise.

[ Table 1]

	T1	T2	C1	C2	C3
						SBR ⁽¹⁾	100％	-	-	-	-
NR ⁽²⁾	-	100％	100	100	-
						ENR50 ⁽³⁾	-	-	-	-	100％
PE-1 ⁽⁴⁾	-	-	15％	-	-
						PE-2 ⁽⁵⁾	-	-	-	15％	14
Carbon black ⁽⁶⁾	60％	40	46	46	43
						Silicon dioxide ⁽⁷⁾	-	15％	17	17	16

						Tan(δ)60℃	100％	176	115	125	115
Perfo crawler belt	100％	85	198	191	234

(1) Tin-functionalized solution SBR having 5% of 1,2-polybutadiene units, 29% of styrene units-Tg = -52 DEG C

(2) Natural rubber

(3) 50 mol% of epoxidized natural rubber (Epoxyprene 50 from Guthrie)

(4) PE-1: high Density Polyethylene (HDPE) MP90U from ENI Versalis (MP =137 ℃ C.)

(5) PE-2: maleic anhydride functionalized polyethylene Exxelor from ExxonMobil ^TM PE 1040(Mp＝134℃)

(6) N115 grade carbon black meeting standard ASTM D-1765

(7) Ultrasil VN3 from Evonik

The results given in table 1 above show that the use of a filler system comprising polyethylene having a melting point between 120 ℃ and 160 ℃, carbon black and silica, according to the invention, enables a great improvement in the resistance to attack without impairing, or even at the same time improving, the hysteresis.

Claims

1. Rubber composition based on at least one diene elastomer, from 10phr to 60phr of carbon black, from 5phr to 30phr of silica, a polyethylene having a melting point between 120 ℃ and 160 ℃, and a crosslinking system, in which composition the carbon black represents from 50% to 95% by weight relative to the total weight of carbon black and silica.

2. The rubber composition according to claim 1, wherein the diene elastomer is selected from the group consisting of polybutadiene, synthetic polyisoprene, natural rubber, butadiene copolymers, isoprene copolymers and mixtures of these elastomers, preferably from the group consisting of synthetic polyisoprene, natural rubber and mixtures thereof.

3. The composition of claim 1, wherein the diene elastomer consists essentially of at least one epoxidized polyisoprene having a molar epoxidation degree ranging from 5% to 85%.

4. Composition according to any one of the preceding claims, in which the content of carbon black is within the range from 15phr to 55phr, preferably from 30phr to 50phr.

5. Composition according to any one of the preceding claims, in which the content of silica is in the range from 5phr to 25phr, preferably from 6phr to 20 phr.

6. Composition according to any one of the preceding claims, which does not comprise a coupling agent, or comprises less than 6% by weight of coupling agent relative to the weight of silica, preferably comprises less than 2% by weight of coupling agent relative to the weight of silica.

7. Composition according to any one of the preceding claims, in which 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.

8. Composition according to any one of the preceding claims, in which the polyethylene is functionalized with a function selected from maleic anhydride functions, epoxy functions, amine functions and acid functions, preferably with maleic anhydride functions.

9. Composition according to any one of the preceding claims, in which the polyethylene comprises no polypropylene units or less than 10% by weight of polypropylene units relative to the total weight of the polyethylene.

10. Composition according to any one of the preceding claims, in which the content of polyethylene having a melting point of between 120 ℃ and 160 ℃ is in the range from 3phr to 40phr, preferably from 5phr to 30 phr.

11. Composition according to any one of the preceding claims, in which the total content of carbon black, silica and polyethylene having a melting point of between 120 ℃ and 160 ℃ is in the range from 20phr to 90phr, preferably from 30phr to 80 phr.

12. Process for preparing a composition according to any one of claims 1 to 11, characterized in that it comprises the following steps:

a) Simultaneously or sequentially contacting and mixing at least one diene elastomer, a filler comprising carbon black and silica, and a polyethylene having a melting point between 120 ℃ and 160 ℃ in one or more portions, the carbon black representing 50% to 95% by weight relative to the total weight of carbon black and silica, thermomechanically kneading all the substances until a maximum temperature T1 is reached, said maximum temperature T1 being greater than or equal to the melting point of the polyethylene,

13. A rubber composition obtainable by the process according to claim 12.

14. A rubber article comprising a composition as defined in any one of claims 1 to 11 or 13.

15. The rubber article of claim 14, said article being selected from the group consisting of pneumatic tires, non-pneumatic tires, tracks, and conveyor belts.