WO2019073145A1 - Tyre provided with a tread including at least one butyl rubber and a butadiene and styrene copolymer - Google Patents

Abstract

The present invention relates to tyres, in particular suitable for driving over surfaces that are covered with snow and have reduced rolling friction, the tread of which includes a rubber composition made up of at least 40 to 90 phe of a styrene and butadiene copolymer having at least one alkoxysilane group bonded to the copolymer by the silicon atom thereof, 10 to 60 phe of a butyl rubber, 90 to 200 phe of a reinforcing inorganic filler, at least 40 phe of a liquid plasticiser at 23°C, and a cross-linking system.

Description

 TIRE COMPRISING A TREAD WITH AT LEAST ONE BUTYL RUBBER AND A COPOLYMER BASED ON BUTADIENE AND STYRENE

The present invention relates to tread tires, in particular snow or winter tread, suitable for driving on soils covered with snow (in English called "snow tires" or "winter tires"). In known manner, these snow tires marked with an inscription M + S or MS or M & S, marked on their sides, are characterized by a tread design and a structure intended primarily to ensure in the mud and fresh snow or melting behavior better than that of road type tires (in English called "road tire type") designed to ride on non-snowy ground.

Snowy soils, so-called white soils, have the characteristic of having a low coefficient of friction, which has led to the development of snow tires comprising treads based on diene rubber compositions having a low glass transition temperature, Tg. However, the wet grip performance of these tires comprising such treads is generally lower than that of road tires whose treads are generally based on rubber compositions of different formulations, especially at higher Tg. to answer this problem, the application WO 2012/069565 proposes a tread whose composition comprises a diene elastomer carrying at least one SiOR function, R being a hydrogen or a hydrocarbon radical in combination with a high level of reinforcing inorganic filler and d a specific plasticizer system.

Moreover, since fuel savings and the need to protect the environment have become a priority, it is desirable to use rubber compositions that can be used for the manufacture of various semi-finished products used in the construction of packaging envelopes. pneumatic tires with reduced rolling resistance. However, the decrease in rolling resistance is often antithetical to the improvement of grip both on wet and on snowy ground.

Thus, manufacturers are still seeking solutions to further improve the rolling resistance and / or snow-covered grip of snow tires, preferably without penalizing the other properties of the tires, particularly wet grip.

Continuing its research, the Applicant has unexpectedly discovered that the combined use of certain functional diene elastomers with a butyl rubber, an inorganic reinforcing filler and a plasticizer system, allowed to further improve the rolling resistance and grip performance on snow.

Thus, the subject of the invention is a tire whose tread comprises a rubber composition based on at least:

 from 40 to 90 phr of a copolymer based on styrene and butadiene bearing at least one alkoxysilane group bonded to the copolymer by its silicon atom, from 10 to 60 phr of a butyl rubber,

 from 90 to 200 phr of a reinforcing inorganic filler,

 at least 40 phr of a liquid plasticizer at 23 ° C.,

 a crosslinking system.

The present invention particularly relates, without being limited to, tires intended to equip motor vehicles of tourism type, SUV ("Sport Utility Vehicles"), or two wheels (including motorcycles), or industrial vehicles chosen among vans, " Heavyweight "- that is, metro, bus, road transport equipment (trucks, tractors, trailers, and others).

The invention as well as its advantages will be readily understood in the light of the description and the following exemplary embodiments.

I- DEFINITIONS

 By the expression "part by weight per hundred parts by weight of elastomer" (or phr) is meant for the purposes of the present invention, the part, by mass per hundred parts by weight of elastomer or rubber.

In the present, unless expressly indicated otherwise, all the percentages (%) indicated are percentages (%) by mass.

On the other hand, any range of values designated by the expression "between a and b" represents the range of values from more than a to less than b (i.e. terminals a and b excluded) while any range of values designated by the term "from a to b" means the range from a to b (i.e., including the strict limits a and b). In the present invention, when a range of values is designated by the expression "from a to b", the interval represented by the expression "between a and b" is also designated and preferentially.

As used herein, "composition based on" is understood to mean a composition comprising the mixture and / or the reaction product in situ of the various constituents used, some of these constituents being capable of or intended to react between them, at least in part, during the different phases of manufacture of the composition, in particular during its crosslinking or vulcanization.

When reference is made to a "majority" compound, in the sense of the present invention, it is understood that this compound is predominant among the compounds of the same type in the composition, that is to say that it is the one which represents the greater amount by mass among the compounds of the same type, for example more than 50%, 60%, 70%, 80%, 90% or even 100% by weight relative to the total weight of the type of compound. Thus, for example, a majority reinforcing filler is the reinforcing filler representing the largest mass relative to the total weight of the reinforcing fillers in the composition. In contrast, a "minor" compound is a compound that does not represent the largest mass fraction among compounds of the same type, for example less than 50%, 40%, 30%, 20%, 10% or less. In the context of the invention, the compounds comprising carbon mentioned in the description may be of fossil origin or biobased. In the latter case, they can be, partially or totally, derived from biomass or obtained from renewable raw materials derived from biomass. These include polymers, plasticizers, fillers, etc.

Unless otherwise indicated, when the term "composition" or "rubber composition" is used, reference is made to the rubber composition of the tread of the tire according to the present invention.

II- DESCRIPTION OF THE INVENTION

elastomer matrix

 According to the invention, the composition of the tread of the tire comprises at least 40 to 90 phr of a copolymer based on styrene and butadiene bearing at least one alkoxysilane group bonded to the copolymer by its silicon atom and to 60 phr of a butyl rubber.

11-1.1 Copolymer based on styrene and butadiene

In the present, unless otherwise indicated, when the term "styrene-butadiene-based copolymer" is used, reference is made to the styrene-butadiene-based copolymer used in the context of the present invention. that is to say the copolymer based on styrene and butadiene bearing at least one alkoxysilane group bonded to the copolymer by its silicon atom. Such copolymers and the process for obtaining them are described in particular in patent documents US Pat. No. 5,977,238 and WO 2009/133068. For the purposes of the present invention, the term "styrene-butadiene-based copolymer" refers to any copolymer obtained by copolymerization of one or more styrenic compounds with one or more butadiene (s). As styrene monomers are especially suitable styrene, methylstyrenes, para-tert-butylstyrene, methoxystyrenes, chlorostyrenes. As butadiene monomers 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-di (C ₁ -C ₅ alkyl) -1,3-butadienes, such as, for example, 2,3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-methyl-3-ethyl-1,3-butadiene, 2-methyl-3-isopropyl-1 , 3-butadiene and aryl-1,3-butadiene. These elastomers may have any microstructure which is a function of the polymerization conditions used, in particular the presence or absence of a modifying and / or randomizing agent and amounts of modifying and / or randomizing agent used. The elastomers can be, for example, blocks, statistics, sequenced, microsequenced. According to the invention, the copolymer based on styrene and butadiene is advantageously a styrene-butadiene copolymer (SBR).

Preferably, the copolymer based on styrene and butadiene is composed of styrene monomers and butadiene monomers, that is to say that the sum of the molar percentages of monomers of styrene and butadiene monomers is equal to 100%.

It should be noted that the SBR can be prepared in emulsion (ESBR) or in solution (SSBR). Whether ESBR or SSBR, the SBR can be any microstructure. In particular, it is possible to use an SBR having a low styrene content, for example from 0 to 10%, an average styrene content, for example between 10% and 35% by weight, or a high styrene content, for example from 35 to 55%, a vinyl bond content of the butadiene part of between 4% and 70%, and a Tg of less than -40 ° C, preferably less than -50 ° C.

The glass transition temperature Tg is measured in a known manner by DSC (Differential Scanning Calorimetry), according to the ASTM D3418 (1999) standard.

Preferably, the styrene-butadiene-based copolymer has any combination of two or three, or all of the following:

 it is a styrene-butadiene copolymer prepared in solution (SSBR),

its styrene content is between 1 and 15%, preferably between 1 and 4%, its vinyl bond content of the butadiene part of between 4 and 25%, preferably between 10 and 15%, its Tg is less than -70 ° C, preferably less than -80 ° C, preferably between -100 ° C and -80 ° C.

According to the invention, the alkoxysilane group of the copolymer of styrene and butadiene may be at the end of the elastomeric chain.

Alternatively, and advantageously, the alkoxysilane group is located inside (or "in") the elastomeric chain, it will be said that the copolymer of styrene and butadiene is coupled (or further functionalized) in the middle of the chain, as opposed to the position "chain end", and this, although the group is not precisely in the middle (or "center") of the elastomeric chain. The silicon atom of this function binds the two main branches of the elastomeric chain of the copolymer of styrene and butadiene. The alkoxysilane group may carry a further function carried preferably by the silicon of the alkoxysilane group, directly (ie via a covalent bond) or via a spacer group defined as being a atom or a radica the divalent hydrocarbon, linear or branched, aliphatic Cl-Cl ₈ saturated or unsaturated, cyclic or not, or an aromatic divalent hydrocarbon radical with C ₆ -C _8.

The other function is preferably a functional group comprising at least one heteroatom selected from among N, S, O, P. It is possible, by way of example, to mention among these functions, primary, secondary or tertiary amines, cyclic or otherwise, isocyanates, imines, cyano, thiols, carboxylates, epoxides, primary, secondary or tertiary phosphines.

Thus, as a secondary or tertiary amine function, amino include substituted alkyl radicals Ci-Ci _0, preferably alkyl-C _4, more preferably a methyl or ethyl radical, or else cyclic amines forming a heterocycle containing a nitrogen atom and at least one carbon atom, preferably from 2 to 6 carbon atoms. For example, metylamino-, dimethylamino-, ethylamino-, diethylamino-, propylamino-, dipropylamino-, butylamino-, dibutylamino-, pentylamino-, dipentylamino-, hexylamino-, dihexylamino-, hexamethyleneamino- groups, preferably the diethylamino groups, are suitable. and dimethylamino.

As an imine function, mention may be made of ketimines. For example, (1,3-dimethylbutylidene) amino-, (ethylidene) amino-, (1-methylpropylidene) amino-, (4-N, N-dimethylaminobenzylidene) amino-, (cyclohexylidene) amino-, dihydroimidazole and imidazole. Thus, as a carboxylate function, mention may be made of acrylates or methacrylates. Such a function is preferably a methacrylate.

As an epoxide function, mention may be made of epoxy or glycidyloxy groups.

As secondary or tertiary phosphine functional groups, mention may be made of phosphines substituted with C ₁ -C 10 alkyl radicals, preferably C ₁ -C ₄ alkyl radicals, more preferentially methyl or ethyl radicals, or diphenylphosphine radicals. For example, metylphosphino-, dimethylphosphino-, ethylphosphino-, diethylphosphino, ethylmethylphosphino- and diphenylphosphino- groups are suitable.

Particularly advantageously, the alkoxysilane group carries an amine function. In this case, the alkoxysilane group may also be referred to as "amino-functional group aikoxysilane" or "amino-alkoxysilane group", the two terms having the same meaning. The amine function may be a primary, secondary or tertiary amine function. Preferably, the amine function is a tertiary amine function, preferably chosen from diethylamine and dimethylamine.

The primary, secondary or tertiary amine function can be carried directly (by a covalent bond) by the silicon atom of the alkoxysilane group of the copolymer based on styrene and butadiene, or by means of a spacer group. The spacer group may especially be a divalent hydrocarbon radical, linear or branched alkyl of ₀ Ci_i, aryl C ₆ -is or aralkyl C ₇ _i _8. Preferably the spacer group is a C2-3 linear hydrocarbon radical.

According to the invention, the alkoxysilane group bearing the primary, secondary or tertiary amine function has one of the following formulas (I) to (III):

 Formula (II) Formula (III in which:

 E denotes the copolymer based on styrene and butadiene,

R 1 and R ₆ , which are identical or different, denote the copolymer based on styrene and butadiene or an oxygen atom substituted with a hydrogen atom or a alkyl radical, linear or branched Ci_i ₀ cycloalkyl, C ₅ _i _8, C ₆ -is aralkyl or C ₇ _i _8;

R ₂ is a divalent hydrocarbon radical, linear or branched alkyl Ci_i _0, aryl C ₆ -is or aralkyl C ₇ _i _8;

R ₃ and R ₄ , which may be identical or different, represent a hydrogen atom or a C ₁ -C ₁₀ alkyl radical, provided that when one of R ₃ and R ₄ represents a hydrogen atom the other is different, or else R ₃ and R ₄ form with N to which they are bonded a heterocycle containing a nitrogen atom and at least one carbon atom;

R ₅ represents a linear or branched C ₁ -C ₁₀ alkylidene radical;

 the symbols A denote, independently of one another, a nitrogen atom or a carbon atom, provided that at least one of the symbols A denotes a nitrogen atom. Advantageously, the alkoxysilane group carrying the primary, secondary or tertiary amine function corresponds to one of the formulas (I) to (III) above in which:

 R 1 represents an oxygen atom substituted by a methyl or ethyl radical; and or

R ₂ represents the ethane-1,2-diyl or propane-1,3-diyl radical; and or,

R ₃ and R ₄ , which may be identical or different, represent a methyl or ethyl radical; and or

R ₅ represents a linear or branched C ₄ -C ₆ alkylidene radical; and or

a single A designates a nitrogen atom and is located in the meta or para position of the ring with respect to -R ₂ ; and or

R ₆ denotes the copolymer based on styrene and butadiene

The styrene-butadiene copolymer bearing an amino-alkoxysilane group bonded to the diene elastomer by the silicon atom as defined herein can be prepared by techniques known to those skilled in the art, for example according to a suitable method described in the application WO 2009/133068 or the application WO 2017/060395.

The process for preparing the styrene-butadiene-based copolymer bearing an amino-alkoxysilane group bonded to the diene elastomer by the silicon atom as defined herein may in particular comprise a stripping step in order to recover the elastomer in dry form. This stripping step may have the effect of hydrolyzing all or part of the hydrolyzable alkoxysilane functions of said copolymer to convert them into silanol functions. For example, at least 50 mol% of the functions can thus be hydrolysed.

Thus, according to the invention, the alkoxysilane group of the styrene and butadiene copolymer bearing an amino-alkoxysilane group bonded to the diene elastomer by the atom silicon as defined herein may be partially or fully hydrolysed to silanol.

The copolymer based on styrene and butadiene may also have additional starring by reaction with a staring agent known per se, for example based on tin or silicon. Preferably, the copolymer based on styrene and butadiene is functionalized with tin (Sn), that is to say that they comprise a C-Sn bond (also called Sn functionalization). They can be functionalized simply (C-Sn bond at the end of the chain), coupled (Sn atom between two chains) and / or starred (Sn atom between 3 or more chains) with a functionalising agent, coupling and / or starring. Generically, we are talking about bringing together all these elastomers bound to tin, elastomers functionalized with tin. These elastomers are known to those skilled in the art, for example those described in application WO 2011/042507. Advantageously, the level of the copolymer based on styrene and butadiene in the composition of the tread of the tire according to the invention is in a range from 50 to 90 phr, preferably from 60 to 90 phr.

11-1.2 Butyl rubber

By butyl rubber is meant in known manner a copolymer of isobutylene and C ₄ -C ₆ diene, preferably isoprene (abbreviated IIR), and the halogenated versions, preferably chlorinated or brominated, of this type of compound. copolymer. Generally, butyl rubbers contain from 1 to 5% by mole of diene unit, in particular isoprenic unit.

The halogenated butyl rubbers are obtained by halogenation, in particular by chlorination or bromination of the copolymers of isobutylene and of C ₄ -C ₆ diene, especially of isoprene. The halogen content in the halogenated butyl rubber is preferably in a range from 1 to 4% by weight relative to the weight of the butyl rubber.

Preferably, according to the invention, the butyl rubber is a halogenated butyl rubber preferably chlorinated or brominated, more preferably a brominated butyl rubber. More preferably, the butyl rubber is a copolymer of isobutylene and halogenated isoprene (XIIR), preferably chlorinated (Cl I R) or brominated (BIIR), preferably a copolymer of isobutylene and brominated isoprene.

By extension of the definition of butyl rubber, butyl rubber may also be a terpolymer of isobutylene, paramethylstyrene and halogenated paramethylstyrene, preferentially brominated, sold under the name Bromobutyl 2222 from Exxon or X BUTYLTM BB 2030 from Arlanxeo. Advantageously, the butyl rubber has a molar mass of between 60,000 and 500,000 g / mol, preferably between 90,000 and 300,000 g / mol. Advantageously, the level of the butyl rubber in the tread composition of the tire according to the invention is in a range from 10 to 50 phr, preferably from 10 to 40 phr.

11-1.3 Other elastomer or polymer

Although this is not necessary for the implementation of the present invention, the elastomeric matrix of the composition according to the invention may contain, in a minority manner, one or more different diene elastomers (hereinafter referred to as "another diene elastomer" in a drafting simplicity) of the copolymer based on styrene and butadiene and butyl rubber used in the context of the present invention. For example, the other diene elastomer may be chosen, for example, from the group of highly unsaturated diene elastomers consisting of polybutadienes (abbreviated to "BR"), natural rubber (NR), synthetic polyisoprene (IR), butadiene copolymers, isoprene copolymers (other than IIR) and mixtures of these elastomers. Such copolymers may for example be chosen from the group consisting of butadiene-styrene copolymers (SBR) different from the styrene-butadiene-based copolymer used in the context of the present invention, isoprene-butadiene copolymers (BIR ), isoprene-styrene copolymers (SIR), isoprene-butadiene-styrene copolymers (SBIR), butadiene-acrylonitrile copolymers (NBR), butadiene-styrene-acrylonitrile copolymers (NSBR), or a mixture of of two or more of these compounds. Preferably, the elastomeric matrix contains no other diene elastomer or contains less than 20 phr, preferably less than 10 phr, more preferably less than 5 phr.

The elastomeric matrix may also contain, in a minority manner, any type of synthetic elastomer other than diene, or even with polymers other than elastomers, for example thermoplastic polymers. Preferably, the elastomeric matrix contains no synthetic elastomer other than diene or polymer other than elastomers or contains less than 10 phr, preferably less than 5 phr.

Thus, according to the invention, the total amount of the copolymer based on styrene and butadiene and butyl rubber the composition of the tread of the tire according to the invention is advantageously in a range from 80 to 100 phr, preferably 90 to 100 phr, more preferably 95 to 100 phr. Particularly advantageously, the total content of the styrene-butadiene-based copolymer and the butyl rubber, the composition of the tread of the tire according to the invention is 100 phr. 11-2 Reinforcing filler

As another essential characteristic, the rubber composition of the tread of the tire according to the invention comprises a reinforcing inorganic filler in a proportion ranging from 90 to 200 phr. "Reinforcing inorganic filler" means any inorganic or mineral filler, irrespective of its color and origin (natural or synthetic), also called "white" filler, "clear" filler or even "non-black filler" as opposed to carbon black, capable of reinforcing on its own, without any other means than an intermediate coupling agent, a rubber composition intended for the manufacture of pneumatic tires, in other words able to replace, in its function reinforcement, a conventional carbon black of pneumatic grade; such a filler is generally characterized, in known manner, by the presence of hydroxyl groups (-OH) on its surface. Suitable reinforcing inorganic fillers are in particular mineral fillers of the siliceous type, preferentially silica (SiO ₂ ). The silica used may be any reinforcing silica known to those skilled in the art, in particular any precipitated or fumed silica having a BET surface and a CTAB specific surface both less than 450 m ² / g, preferably from 30 to 400 m ² / g, in particular between 60 and 300 m ² / g-A of highly dispersible precipitated silicas (called "HDS"), there may be mentioned for example the silicas "Ultrasil" 7000 and "Ultrasil" 7005 from the company Degussa, silicas "Zeosil" 1165M P, 1135MP and 1115MP from Rhodia, the "Hi-Sil" silica EZ150G from PPG, the "Zeopol" silicas 8715, 8745 and 8755 from Huber, high surface area silicas such as described in WO 03/16387.

As reinforcing inorganic filler, mention may also be made of mineral fillers of the aluminous type, in particular alumina (Al ₂ O ₃ ) or aluminum (oxide) hydroxides, or reinforcing titanium oxides. Those skilled in the art will understand that as an equivalent load of the reinforcing inorganic filler described in this paragraph, it would be possible to use a reinforcing filler of another nature, in particular an organic filler such as carbon black, since this filler reinforcing would be covered with an inorganic layer such as silica, or would comprise on its surface functional sites, including hydroxyl, requiring the use of a coupling agent to establish the connection between the filler and the elastomer. By way of example, for example, there may be mentioned carbon blacks for tires as described for example in the patent documents WO 96/37547 and WO 99/28380.

Advantageously, the level of reinforcing inorganic filler is in a range from 95 to 180 phr, more preferably from 100 to 150 phr, more advantageously from 105 to 140 phr.

Advantageously, the reinforcing inorganic filler mainly comprises silica. More preferably, the reinforcing inorganic filler is (or consists of) silica.

In order to couple the reinforcing inorganic filler to the diene elastomer, an at least bifunctional coupling agent (or bonding agent) is used in a well-known manner to ensure a sufficient chemical and / or physical connection between the inorganic filler (surface of its particles) and the diene elastomer. In particular, organosilanes or at least bifunctional polyorganosiloxanes are used.

Those skilled in the art can find examples of coupling agent 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.

The content of coupling agent is advantageously from 0.5% to 15% by weight relative to the amount of reinforcing inorganic filler, preferably from 4 to 12%, more preferably from 6 to 10% by weight relative to the amount of reinforcing inorganic filler. Typically, the level of coupling agent is less than 20 phr, preferably in a range from 6 to 17 phr, preferably from 8 to 15 phr. This level can easily be adjusted by those skilled in the art according to the level of inorganic filler used in the composition.

The rubber composition of the tire according to the invention may also contain, in addition to the coupling agents, coupling activators, inorganic charge-covering agents or, more generally, processing aid agents capable in known manner. by improving the dispersion of the filler in the rubber matrix and lowering the viscosity of the compositions, to improve their ability to use in the green state, these agents being for example hydrolysable silanes such as alkylalkoxysilanes (especially alkyltriethoxysilanes), polyols, polyethers (for example polyethylene glycols), primary, secondary or tertiary amines (for example trialkanol amines), hydroxylated or hydrolyzable POSs, for example α, ω- dihydroxy-polyorganosiloxanes (In particular, α, ω-dihydroxy-polydimethylsiloxanes), fatty acids, for example stearic acid.

Although it is not necessary for the implementation of the present invention, the rubber composition of the tread of the tire according to the invention may comprise carbon black. According to the invention, the composition does not comprise carbon black, or comprises less than 20 phr, preferably less than 10 phr (for example between 0.5 and 20 phr, in particular between 1 and 10 phr, for example between 2 and 5 pce). In the ranges indicated, it benefits from the coloring properties (black pigmentation agent) and anti-UV carbon blacks, without otherwise penalizing the typical performance provided by the reinforcing inorganic filler.

The blacks that can be used in the context of the present invention may be all black conventionally used in tires or their treads (so-called pneumatic grade blacks). Among the latter, there will be mentioned more particularly the reinforcing carbon blacks of the series 100, 200, 300, or the series blacks 500, 600 or 700 (ASTM grades), such as, for example, the blacks N115, N134, N234, N326, N330. , N339, N347, N375, N550, N683, N772). These carbon blacks can be used in the isolated state, as commercially available, or in any other form, for example as a carrier for some of the rubber additives used. The carbon blacks could for example already be incorporated into the diene elastomer, in particular isoprene in the form of a masterbatch (see for example applications WO 97/36724 or WO 99/16600). The BET surface area of the carbon blacks is measured according to the D6556-10 standard [multipoint method (at least 5 points) - gas: nitrogen - relative pressure range Ρ / Ρ0: 0.1 to 0.3].

11-3 Plasticizer

 11-3.1 Liquid plasticizer at 23 ° C

 The rubber composition of the tread of the tire according to the invention further comprises at least 40 phr of a liquid plasticizer at 23 ° C.

Any plasticizer liquid at 23 ° C (or extension oil), whether aromatic or non-aromatic, known for its plasticizing properties vis-à-vis diene elastomers, is usable. At room temperature (23 ° C.), these plasticizers or these oils, more or less viscous, are liquids (that is to say, as a reminder, substances having the capacity to eventually take on the shape of their container) , in contrast in particular to hydrocarbon plasticizing resins which are inherently solid at room temperature. Particularly suitable plasticizers liquid at 23 ° C selected from the group comprising or consisting of liquid diene polymers, polyolefin oils, naphthenic oils, paraffinic oils, DAE oils, MES (Medium Extracted Solvates) oils, Treated Distillate Aromatic Extracts (TDAE) oils, Residual Aromatic Extract oils (RAE), Treated Residual Aromatic Extract (TREE) oils and SRAE oils (Safety Residual Aromatic Extract oils), mineral oils, vegetable oils, ethers plasticizers, ester plasticizers, phosphate plasticizers, sulphonate plasticizers and mixtures of these liquid plasticizers at 23 ° C.

For example, the liquid plasticizer at 23 ° C can be a petroleum oil, preferably non-aromatic. A liquid plasticizer is described as non-aromatic if it has a content of polycyclic aromatic compounds, determined with the extract in DMSO according to the IP 346 method, of less than 3% by weight, relative to the total weight of the plasticizer. .

The liquid plasticizer at 23 ° C. can also be a liquid polymer resulting from the polymerization of olefins or dienes, such as polybutenes, polydienes, in particular polybutadienes, polyisoprenes (also known as the "LIR") or copolymers of butadiene and isoprene, or copolymers of butadiene or isoprene and styrene or mixtures of these liquid polymers. The number-average molar mass of such liquid polymers is preferably in a range from 500 g / mol to 50,000 g / mol, preferably from 1,000 g / mol to 10,000 g / mol. For example, the products "RICON" by SARTOMER can be mentioned.

When the plasticizer liquid at 23 ° C is a vegetable oil, it may be for example an oil selected from the group comprising or consisting of linseed oil, safflower, soybean, corn, cotton, shuttle, castor, abrasin , pine, sunflower, palm, olive, coconut, peanut, grape seed and blends of these oils. The vegetable oil is preferably rich in oleic acid, that is to say that the fatty acid (or all the fatty acids if several are present) from which it derives, comprises oleic acid in a mass fraction at least 60%, even more preferably in a mass fraction of at least 70%. As a vegetable oil, a sunflower oil is advantageously used which is such that all of the fatty acids from which it is derived comprise oleic acid in a mass fraction equal to or greater than 60%, preferably 70% and, according to a particularly advantageous embodiment of the invention, in a mass fraction equal to or greater than 80%.

According to another particular embodiment of the invention, the liquid plasticizer is a triester selected from the group consisting of triesters of carboxylic acid, phosphoric acid, sulfonic acid and mixtures of these triesters. As examples of phosphate plasticizers, mention may be made of those containing from 12 to 30 carbon atoms, for example trioctyl phosphate. By way of examples of carboxylic acid ester plasticizers, mention may be made in particular of compounds selected from the group consisting of trimellitates, pyromellitates, phthalates, 1,2-cyclohexane dicarboxylates, adipates, azelates and sebacates. glycerol triesters and mixtures thereof. Among the triesters above, mention may be made especially of glycerol triesters, preferably consisting mainly (for more than 50%, more preferably for more than 80% by weight) of a C 18 unsaturated fatty acid, that is, that is, selected from the group consisting of oleic acid, linoleic acid, linolenic acid, and mixtures of these acids. The glycerol triester is preferred. More preferably, whether of synthetic or natural origin (for example by vegetable oils of sunflower or rapeseed), the fatty acid used is more than 50% by weight, more preferably still for more than 50% by weight. 80% by weight of oleic acid. Such high oleic acid triesters (trioleates) are well known and have been described, for example, in application WO 02/088238, as plasticizers in tire treads.

When the liquid plasticizer at 23 ° C is a plasticizer ether, it may be for example polyethylene glycol or polypropylene glycol.

Preferably, the liquid plasticizer at 23 ° C. is chosen from the group consisting of or consisting of M ES oils, TDAE oils, naphthenic oils, vegetable oils and mixtures of these mixtures of these liquid plasticizers at 23 ° C. . More preferably, the liquid plasticizer at 23 ° C is a vegetable oil, preferably a sunflower oil.

As indicated above, the level of plasticizer liquid at 23 ° C in the composition of the tread of the tire according to the invention is at least 40 phr. Below this level, the rolling resistance and adhesion properties on snow-covered ground are no longer optimal. Thus, preferably, the level of liquid plasticizer at 23 ° C. in the composition is preferably within a range from 40 to 100 phr, preferably from 50 to 90 phr, more preferably from 55 to 80 phr.

Furthermore, it is particularly advantageous for the ratio of the level of reinforcing inorganic filler to the level of liquid plasticizer at 23 ° C. in the rubber composition to be in a range from 1.5 to 3; preferably from 1.6 to 2.5; more preferably 1.8 to 2.2.

11-3.2 Hydrocarbon resin

Although this is not necessary for the implementation of the present invention, the rubber composition of the tread of the tire according to the invention may comprise a hydrocarbon resin having a glass transition temperature greater than 20 ° C (hereinafter referred to as "hydrocarbon resin"). According to the invention, the composition does not comprise a hydrocarbon resin, or comprises at most 50 phr, preferably at most 40 phr. When the composition comprises a hydrocarbon-based resin, it may comprise from 10 to 50 phr, preferably from 15 to 40 phr.

The term "resin" is hereby reserved, by definition known to those skilled in the art, to a compound that is solid at room temperature (23 ° C), as opposed to a liquid plasticizer such as an oil.

Hydrocarbon resins are polymers well known to those skilled in the art, essentially based on carbon and hydrogen but may include other types of atoms, used in particular as plasticizers or tackifying agents in polymeric matrices. They are inherently miscible (i.e., compatible) with the levels used with the polymer compositions for which they are intended, so as to act as true diluents. They have been described, for example, in the book "Hydrocarbon Resins" by R. Mildenberg, M. Zander and G. Collin (New York, VCH, 1997, ISBN 3-527-28617-9), chapter 5 of which is devoted their applications, in particular pneumatic rubber (5.5 "Rubber Tires and Mechanical Goods"). They can be aliphatic, cycloaliphatic, aromatic, hydrogenated aromatic, aliphatic / aromatic type that is to say based on aliphatic and / or aromatic monomers. They may be natural or synthetic, whether or not based on petroleum (if so, also known as petroleum resins). Their Tg is preferably greater than 20 ° C (most often between 30 ° C and 95 ° C).

In a known manner, these hydrocarbon resins can also be described as thermoplastic resins in that they soften by heating and can thus be molded. They can also be defined by a point or softening point (in English, "softening point"). The softening temperature of a hydrocarbon resin is generally about 50 to 60 ° C. higher than its Tg value. The softening point is measured according to ISO 4625 ("Ring and Bail" method). The macrostructure (Mw, Mn and Ip) is determined by size exclusion chromatography (SEC) as indicated below. As a reminder, the SEC analysis, for example, consists in separating the macromolecules in solution according to their size through columns filled with a porous gel; the molecules are separated according to their hydrodynamic volume, the larger ones being eluted first. The sample to be analyzed is simply solubilized beforehand in a suitable solvent, tetrahydrofuran at a concentration of 1 g / liter. Then the solution is filtered on a 0.45 μιη porosity filter before injection into the apparatus. The equipment used is for example a chromatographic chain "Waters alliance" according to the following conditions:

 elution solvent is tetrahydrofuran,

 temperature 35 ° C;

 - concentration 1 g / liter;

 flow rate: 1 ml / min;

 injected volume: 100 μΙ;

 Moore calibration with polystyrene standards;

 - set of 3 columns "Waters" in series ("Styragel HR4E", "Styragel HR1" and "Styragel HR 0.5");

 detection by differential refractometer (for example "WATERS 2410") that can be equipped with operating software (for example "Waters Millenium").

A Moore calibration is conducted with a series of low Ip (less than 1.2) polystyrene commercial standards of known molar masses covering the field of masses to be analyzed. The mass-averaged molecular weight (Mw), the number-average molecular weight (Mn) and the polymolecularity index (Ip = Mw / Mn) are deduced from the recorded data (mass distribution curve of the molar masses). All the molar mass values indicated in the present application are therefore relative to calibration curves made with polystyrene standards.

According to a preferred embodiment of the invention, the hydrocarbon resin has at least one, more preferably all of the following characteristics:

 a Tg greater than 25 ° C (in particular between 30 ° C and 100 ° C), more preferably greater than 30 ° C (in particular between 30 ° C and 95 ° C); a softening point greater than 50 ° C (in particular between 50 ° C and

150 ° C);

 a number-average molar mass (Mn) of between 400 and 2000 g / mol, preferably between 500 and 1500 g / mol;

a polymolecularity index (Ip) of less than 3, preferably of 2 (booster: Ip = Mw / Mn with Mw weight average molar mass). According to the invention, the hydrocarbon resin may be chosen from the group consisting of or consisting of homopolymer or copolymer resins of cyclopentadiene (abbreviated to CPD), homopolymer or copolymer resins of dicyclopentadiene (abbreviated to DCPD), resins of terpene homopolymer or copolymer, C5 homopolymer or copolymer resins, C9 homopolymer or copolymer resins, alpha-methylstyrene homopolymer or copolymer resins and mixtures of these hydrocarbon resins . Preferably, the resin hydrocarbon is selected from the group consisting of or consisting of (D) CPD / vinylaromatic copolymer resins, (D) CPD / terpene copolymer resins, terpene phenol copolymer resins, (D) CPD / C5 cut copolymer resins (D) , copolymer resins (D) CPD / C9 cut, terpene / vinylaromatic copolymer resins, terpene / phenol copolymer resins, C5 / vinylaromatic cut copolymer resins, and mixtures of these hydrocarbon resins.

The term "terpene" includes, in a known manner, the alpha-pinene, beta- pinene and limonene monomers; preferably, a limonene monomer is used which is present in a known manner in the form of three possible isomers: L-limonene (laevorotatory enantiomer), D-limonene (dextrorotatory enantiomer), or the dipentene, racemic of the dextrorotatory and levorotatory enantiomers. . Suitable vinylaromatic monomers are, for example, styrene, alpha-methylstyrene, ortho-methylstyrene, meta-methylstyrene, para-methylstyrene, vinyl-toluene, paratertiobutylstyrene, methoxystyrenes, chlorostyrenes and hydroxystyrones. , vinylmesitylene, divinylbenzene, vinylnaphthalene, any vinylaromatic monomer derived from a C ₉ (or more generally from a C ₈ to Ci _0).

More particularly, mention may be made of hydrocarbon resins chosen from the group consisting of (D) CPD homopolymer resins, (D) CPD / styrene copolymer resins, polylimonene resins, limonene / styrene copolymer resins, Limonene / D (CPD) copolymer resins, C5 / styrene cut copolymer resins, C5 / C9 cut copolymer resins, and mixtures of these resins.

All the above hydrocarbon resins are well known to those skilled in the art and commercially available, for example sold by the company DRT under the name "Dercolyte" for polylimonene resins, by the company Neville Chemical Company under the name " Super Nevtac ", by Kolon under the name" Hikorez "or by the company Exxon Mobil under the name" Escorez "with regard to the C ₅ / styrene resins or C ₅ / C ₉ cut resin resins or by the Struktol company under denomination "40 MS" or "40 NS" (mixtures of aromatic and / or aliphatic resins). 11-4 Crosslinking system

 The crosslinking system may be based on molecular sulfur and / or sulfur and / or peroxide donors, well known to those skilled in the art.

The crosslinking system is preferably a sulfur-based vulcanization system (molecular sulfur and / or a sulfur donor agent). Sulfur is used at a preferred level of between 1 and 10 phr, preferably between 1 and 5 phr, more preferably between 1 and 3 phr. The primary vulcanization accelerator may be used at a preferential rate of between 0.2 and 5 phr, more preferably between 0.5 and 3 phr.

The composition of the tread of the tire according to the invention advantageously comprises a vulcanization accelerator, which is preferably selected from the group consisting of thiazole accelerators and their derivatives, sulfenamide, thiourea accelerators and their mixtures. Advantageously, the vulcanization accelerator is selected from the group consisting of 2-mercaptobenzothiazyl disulfide (MBTS), N-cyclohexyl-2-benzothiazyl sulfenamide (CBS), N, N-dicyclohexyl-2-benzothiazyl sulfenamide (DCBS). ), N-tert-butyl-2-benzothiazylsulfenamide (TBBS), N-tert-butyl-2-benzothiazylsulphenide (TBSI), morpholine disulfide, N-morpholino-2-benzothiazylsulphenamide (MBS), dibutylthiourea (DBTU), and mixtures thereof.

The level of vulcanization accelerator is preferably in a range from 0.5 to 3 phr, preferably from 0.6 to 2.5 phr, more preferably from 0.7 to 2 phr. 11-5 Miscellaneous additives

 The rubber composition of the tread of the tire according to the invention may also comprise all or part of the usual additives normally used in tire elastomer compositions, such as, for example, reinforcing resins, fillers other than those mentioned above, pigments, protective agents such as anti-ozone waxes, chemical antiozonants, anti-oxidants, anti-fatigue agents, well known to those skilled in the art.

11-6 Preparation of rubber compositions

 The compositions used in the context of the present invention may be manufactured in appropriate mixers, using two successive preparation phases well known to those skilled in the art: a first phase of work or thermomechanical mixing (so-called "non-productive phase" ") at a high temperature, up to a maximum temperature between 110 ° C and 190 ° C, preferably between 130 ° C and 180 ° C, followed by a second mechanical working phase (so-called" productive "phase) up to at a lower temperature, typically below 110 ° C., for example between 40 ° C. and 100 ° C., a finishing phase during which the crosslinking system is incorporated.

The process for preparing such compositions comprises for example the following steps:

a) incorporating in a diene elastomer, during a first step (called "nonproductive"), a reinforcing filler, by thermomechanically kneading the whole; (for example one or more times) until reaching a maximum temperature of between 110 ° C and 190 ° C;

 b) cooling the assembly to a temperature below 100 ° C;

 c) then incorporate, during a second stage (called "productive"), a crosslinking system;

 d) knead the mixture to a maximum temperature below 110 ° C.

By way of example, the non-productive phase is carried out in a single thermomechanical step during which all the necessary basic constituents (diene elastomer) are introduced into a suitable mixer such as a conventional internal mixer. , reinforcing filler), then in a second step, for example after one to two minutes of mixing, the other additives, optional additional charge-covering or processing agents, with the exception of the crosslinking system. The total mixing time in this non-productive phase is preferably between 1 and 15 minutes.

The first kneading step is generally carried out by incorporating the reinforcing filler to the elastomer in one or more times by thermomechanically kneading. In the case where the reinforcing filler, in particular carbon black, is already incorporated wholly or partly into the elastomer in the form of a masterbatch as described for example in the applications WO 97/36724 or WO 99 / 16600, the masterbatch is directly kneaded and if necessary is incorporated other elastomers or reinforcing fillers present in the composition that are not in the form of masterbatch, as well as additives other than the crosslinking system.

After cooling the mixture thus obtained, it is then incorporated in an external mixer such as a roll mill, maintained at low temperature (for example between 40 ° C and 100 ° C), the crosslinking system. The whole is then mixed (productive phase) for a few minutes, for example between 2 and 15 min.

The final composition thus obtained can then be calendered, for example in the form of a sheet, a plate especially for a characterization in the laboratory, or extruded, for example to form a rubber profile used for the manufacture of a winter tire tread.

According to one particular embodiment, the Shore A hardness of the rubber composition according to the invention is in a range from 45 to 70, in particular from 50 to 65. The Shore A hardness of the compositions after curing is assessed in accordance with the ASTM D 2240-86. The invention relates to the tires previously described both in the green state (that is to say, before firing) and in the fired state (that is to say, after crosslinking or vulcanization).

The cooking can be carried out, in a manner known to those skilled in the art, at a temperature generally of between 130 ° C. and 200 ° C., under pressure, for a sufficient time which may vary, for example, between 5 and 90 min in dependence. in particular, the baking temperature, the crosslinking system adopted, the kinetics of crosslinking of the composition under consideration or the size of the tire comprising a said section.

III- EXAMPLES

l l l-l Measurements and tests used

Dynamic properties:

The dynamic properties G * and tan (5) Max are measured on a viscoanalyzer (Metravib VA4000), according to the ASTM D5992-96 standard. The response of a vulcanized composite sample (cylindrical specimen 2 mm thick and 79 mm ² in section) is recorded, subjected to sinusoidal stress in alternating simple shear, at the frequency of 10 Hz, under the conditions normal temperatures (23 ° C) or at 0 ° C according to ASTM D 1349-09 for measurements of tan (5) Max, or at -10 ° C for G * measurements. A strain amplitude sweep is performed from 0.1% to 50% (forward cycle) and then from 50% to 0.1% (return cycle).

The results used are the complex dynamic shear modulus G * at -10 ° C and the loss factor tan (δ) at 23 ° C. On the return cycle, the value of the G * at 50% deformation is recorded as well as the loss factor, denoted tan (δ) Max.

The results of tan (δ) max at 23 ° C. are expressed in base 100, the value 100 being attributed to the control. A result greater than 100 indicates improved performance, that is, the composition of the example under consideration is less hysteretic at 23 ° C, reflecting lower rolling resistance of the tread comprising such a composition.

The results of tan (δ) max at 0 ° C. are expressed in base 100, the value 100 being attributed to the control. A result greater than 100 indicates improved performance, i.e., the composition of the example considered reflects improved adhesion to a wet floor of the tread comprising such a composition.

The results of G * at -10 ° C are expressed in base 100, the value 100 being attributed to the control. A result greater than 100 indicates an improved performance, that is to say that the composition of the example considered reflects an improved adhesion on a snow-covered ground of the tread comprising such a composition. 111-2 Preparation of compositions

 The following tests are carried out as follows: an internal mixer (final filling ratio: approximately 70% by volume) is introduced, the initial temperature of which is approximately 60 ° C., the elastomer diene, the reinforcing filler, as well as the various other ingredients with the exception of the vulcanization system. Thermomechanical work (non-productive phase) is then carried out in one step, which lasts a total of about 3 to 4 minutes, until a maximum temperature of "fall" of 165 ° C is reached.

The mixture thus obtained is recovered, cooled and then sulfur is incorporated and the vulcanization accelerator, on a mixer (homo-finisher) at 30 ° C, mixing the whole (productive phase) for a suitable time (for example between 5 and 12 minutes). The compositions thus obtained are then calendered either in the form of plates (thickness of 2 to 3 mm) or thin sheets of rubber for the measurement of their physical or mechanical properties, or extruded in the form of a profile.

The samples thus produced were baked for 25 minutes at 150 ° C. in a bell press. The samples were analyzed after cooling for 24 hours at room temperature.

111-3 Rubber Testing

 1-3.1 Comparison of the compositions according to the invention with the prior art

The examples presented below, are intended to compare the rolling resistance and the adhesion on snowy ground of compositions according to the present invention at different levels of butyl rubber (Cl, C2, C3) with a control composition (T) of the prior art, and a control composition (Tl) having a butyl rubber content not according to the present invention. The analyzed formulations (in phr) and the results obtained are presented in Table 1 below.

Table 1

 a) Brominated butyl rubber of 175000g / mol of molecular weight (Tg -60 ° C)

 b) SBR 1: SBR with 3% of styrene unit and 13% of 1,2 unit of the butadiene part carrying an amino-alkoxysilane function in the middle of the elastomer chain (Tg-88C)

 c) SBR 2: SBR (Sn star) with 27% of styrene unit and 24% of 1,2 unit of the butadiene part carrying a silanol function at the end of the elastomer chain (Tg -48 ° C.)

 d) BR: Polybutadiene with 0.5% 1,2- and 97% 1,4-cis (Tg = -108 ° C)

 e) "Zeosil 1165 MP" silica of Rhodia type "HDS"

 f) TESPT ("Si69" from Degussa)

 g) ASTM grade N234 (Cabot company)

 h) Sunflower oil 85% by weight of oleic acid ("Lubrirob Tod 1880" from Novance) i) C5 / C9 resin ("ECR-373 resin" from ExxonMobil)

 j) Polylimonene resin ("Dercolyte L120" from the company DRT)

 k) 2-mercaptobenzothiazyl disulfide ("MTBS" from the company General Quimica)

 I) N-dicylohexyl-2-benzothiazol sulfenamide ("Santocure CBS" from the company Flexsys)

 m) Zinc oxide (industrial grade - Umicore company)

 n) Stearin ('Pristerene 4931' from Uniqema)

 o) 2,2,4-trimethyl-1,2-dihydroquinoline ("TMQ" from the company Lanxess)

 p) Diphenylguanidine ("Perkacit" DPG from Flexsys)

 q) Anti-ozone wax ("VARAZON 4959" from Sasol Wax)

 r) N-1,3-dimethylbutyl-N-phenylparaphenylenediamine ("Santoflex 6-PPD" from Flexsys)

These results show that the compositions in accordance with the invention make it possible to improve both the rolling resistance and the grip on snow-covered soil compared to to the control composition of the prior art. It has been observed that levels greater than 60 phr of butyl rubber cause a decrease in adhesion on snow-covered ground.

111-3.2 Effect of the nature of the elastomeric matrix and the rate of plasticizer

The effect of the nature of the elastomeric matrix and the amount of plasticizer on the rolling resistance and adhesion properties on snow-covered soil was measured and compared with the composition according to the invention Cl. The formulations analyzed (in pce) and the results obtained are shown in Table 2 below. Table 2

 (a) to (q): see table above

 s) SBR 3: SBR (Sn star) with 16% of styrene unit and 24% of 1,2 unit of the butadiene part carrying a silanol function at the end of the elastomeric chain (Tg -65 ° C.)

 t) SBR 4: SBR (Sn star) with 16% styrene and 35% 1,2-butadiene (Tg -65 ° C)

 u) SBR 5: SBR with 27% of styrene unit and 24% of 1.2 unit of butadiene (Tg -48 ° C) v) BR 2: Polybutadiene with 0.5% of 1,2 and 94% units 1.4-cis (Tg = -108 ° C)

These results show that the substitution of the copolymer based on styrene and butadiene according to the invention by another elastomer, functionalized or not, degrades the rolling resistance and grip on snowy ground. The same effects have been observed when the amount of liquid plasticizer is decreased to 23 ° C., whether at a constant plasticizer (T8) or plasticizer resin (T9) level. 1-3.3 Effect of reinforcing inorganic filler

 The effect of the level of reinforcing inorganic filler on the wet adhesion properties was measured and compared with the composition in accordance with the invention Cl. The analyzed formulations (in phr) and the results obtained are shown in Table 3. below.

Table 3

 (a) to (q): see table above

These results show that the reduction of the level of reinforcing inorganic filler in the composition causes degradation of the adhesion on wet ground.

In conclusion, the compositions according to the present invention have a compromise in rolling resistance / grip on snowy ground / adhesion on wet ground much higher than the compositions of the prior art.

Claims

1. A tire whose tread has a rubber composition based on at least:

 from 40 to 90 parts by weight per hundred parts by weight of elastomer, phr, of a copolymer based on styrene and butadiene bearing at least one alkoxysilane group bonded to the copolymer by its silicon atom,

 from 10 to 60 phr of a butyl rubber,

 from 90 to 200 phr of a reinforcing inorganic filler,

 at least 40 phr of a liquid plasticizer at 23 ° C.,

 a crosslinking system.

2. A tire according to claim 1, wherein the styrene-butadiene-based copolymer is a styrene-butadiene copolymer.

A tire according to claim 1 or 2, wherein the alkoxysilane group is disposed within the elastomeric chain of the styrene-butadiene copolymer.

4. A tire according to any one of the preceding claims, wherein the copolymer based on styrene and butadiene additionally carries at least one primary, secondary or tertiary amine function.

5. The tire according to claim 4, wherein the primary, secondary or tertiary amine function is carried, directly or via a spacer group, by the silicon atom of the alkoxysilane group of the styrene-based copolymer. butadiene.

6. A tire according to claim 4 or 5, wherein the alkoxysilane group bearing the primary, secondary or tertiary amine function has one of the following formulas I) to (III):

Formula (II) Formula (III) in which :

 E denotes the copolymer based on styrene and butadiene,

R 1 and R ₆ , which may be identical or different, denote the copolymer based on styrene and butadiene or an oxygen atom substituted with a hydrogen atom or a linear or branched C ₁ -C ₁₀ cycloalkyl or C ₅ alkyl radical. _8, C ₆ -i8 aralkyl or C ₇ _i _8;

R ₂ is a divalent hydrocarbon radical, linear or branched alkyl Ci_i _0, aryl C ₆ -is or aralkyl C ₇ _i _8;

R ₃ and R ₄ , which may be identical or different, represent a hydrogen atom or a Ci- ₁₀ alkyl radical, provided that when one of R ₃ and R ₄ represents a hydrogen atom the other is different, or then R ₃ and R ₄ form with N to which they are bonded a heterocycle containing a nitrogen atom and at least one carbon atom;

R ₅ represents a linear or branched C ₁ -C ₁₀ alkylidene radical;

 the symbols A denote, independently of one another, a nitrogen atom or a carbon atom, provided that at least one of the symbols A denotes a nitrogen atom.

Tire according to claim 6, wherein

 R 1 represents an oxygen atom substituted by a methyl or ethyl radical; and or

R ₂ represents the ethane-1,2-diyl or propane-1,3-diyl radical; and or,

R ₃ and R ₄ , which may be identical or different, represent a methyl or ethyl radical; and or

R ₅ represents a linear or branched C ₄ -C ₆ alkylidene radical; and / or only one A designates a nitrogen atom and is located at the meta or para position of the ring with respect to -R ₂ ; and or

R ₆ denotes the copolymer based on styrene and butadiene.

Tire according to any one of the preceding claims, wherein the styrene-butadiene-based copolymer has a glass transition temperature below -50 ° C, preferably below -70 ° C, more preferably below -80 ° C ° C.

Tire according to any one of the preceding claims, wherein the level of the styrene-butadiene-based copolymer in the rubber composition is in a range from 50 to 90 phr, preferably from 60 to 90 phr.

A tire according to any one of the preceding claims wherein the butyl rubber is a copolymer of isobutylene and C ₄ to C ₆ diene, preferably a copolymer of isobutylene and isoprene. A tire according to any one of the preceding claims, wherein the butyl rubber is a halogenated butyl rubber, preferably brominated butyl rubber.

A tire according to any one of the preceding claims, wherein the butyl rubber has a molar mass of between 60,000 and

500,000 g / mol, preferably between 90,000 and 300,000 g / mol.

A tire according to any one of the preceding claims, wherein the level of butyl rubber in the rubber composition is within a range of 10 to 50 phr, preferably 10 to 40 phr.

Tire according to any one of the preceding claims, in which the total content of the styrene-butadiene-based copolymer and the butyl rubber in the composition is within a range from 80 to 100 phr, preferably from 90 to 100 phr. 100 pce.

15. A tire according to any one of the preceding claims, wherein the total content of the styrene-butadiene-based copolymer and butyl rubber in the composition is 100 phr.

16. A tire according to any one of the preceding claims, wherein the reinforcing inorganic filler is a silica.

Tire according to any one of the preceding claims, wherein the level of reinforcing inorganic filler in the rubber composition is in a range from 95 to 180 phr, preferably from 100 to 150 phr.

18. A tire according to any one of the preceding claims, wherein the level of plasticizer liquid at 23 ° C in the rubber composition is in a range from 40 to 100 phr, preferably from 50 to 90 phr.

Tire according to any one of the preceding claims, in which the ratio of the level of reinforcing inorganic filler to the level of plasticizer liquid at 23 ° C in the rubber composition is in a range from 1.5 to 3; preferably from 1.6 to 2.5; more preferably 1.8 to 2.2.

20. A tire according to any one of the preceding claims, wherein the liquid plasticizer at 23 ° C is selected from the group consisting of liquid diene polymers, polyolefinic oils, naphthenic oils, paraffinic oils, DAE oils, MES oils, TDAE oils, RAE oils, TRAE oils, SRAE oils, mineral oils, vegetable oils, ethers plasticizers, ester plasticizers, phosphate plasticizers, sulphonate plasticizers and mixtures of these liquid plasticizers. 23 ° C.

21. A tire according to any one of the preceding claims, wherein the liquid plasticizer at 23 ° C is selected from the group consisting of MES oils, TDAE oils, naphthenic oils, vegetable oils and mixtures of these liquid plasticizers. at 23 ° C.

22. A tire according to any one of the preceding claims, wherein the rubber composition does not comprise a hydrocarbon resin having a glass transition temperature greater than 20 ° C, or comprises at most 50 phr.

23. A tire according to any one of claims 1 to 22, wherein the rubber composition comprises from 10 to 50 phr of a hydrocarbon resin having a glass transition temperature greater than 20 ° C.

A tire according to any one of claims 22 or 23, wherein the hydrocarbon resin is selected from the group consisting of cyclopentadiene homopolymer or copolymer resins, dicyclopentadiene homopolymer or copolymer resins, resins of terpene homopolymer or copolymer, C ₅ homopolymer or copolymer cut resins, C ₉ homopolymer or copolymer resins, alpha-methyl-styrene homopolymer or copolymer resins and mixtures of these resins hydrocarbon.

25. A tire according to any one of the preceding claims, wherein the rubber composition does not comprise carbon black, or comprises less than 20 phr, preferably less than 10 phr.

Tire according to any one of the preceding claims, wherein the crosslinking system is based on sulfur or a sulfur donor.