FR3053346A1 - PNEUMATIC COMPRISING A COMPOSITION COMPRISING A SPECIFIC SYSTEM OF ELASTOMERS - Google Patents

Abstract

The invention relates to a tire comprising a rubber composition based on at least 30 to 40 phr of polybutadiene, 45 to 60 phr of styrene butadiene copolymer whose styrene content is less than 40% by weight, 0 to 25 phr. of polyisoprene, 90 to 150 phr of inorganic reinforcing filler, 1 to 10 phr of carbon black, 1 to 10 phr of a tackifying resin having a number-average molecular weight (Mn) greater than 800 g / mol and an index of polymolecularity (Ip) greater than or equal to 2.0; and 50 to 100 phr of a plasticizer system comprising 25 to 50 phr of plasticizing oil and 25 to 50 phr of plasticizing resin.

Description

Holder (s): COMPAGNIE GENERALE DES ETABLISSEMENTS MICHELIN Limited partnership with shares, MICHELIN RECHERCHE ET TECHNIQUE S.A. Limited company.

Extension request (s)

Agent (s): MANUF FSE PNEUMATIQUES MICHELIN Limited partnership with shares.

FR 3 053 346 - A1 (54) TIRE COMPRISING A COMPOSITION COMPRISING A SPECIFIC SYSTEM OF ELASTOMERS.

©) The invention relates to a tire comprising a rubber composition based on at least 30 to 40 phr of polybutadiene, 45 to 60 phr of styrene butadiene copolymer, the styrene content of which is less than 40% by weight, 0 to 25 pce of polyisoprene, 90 to 150 pce of inorganic reinforcing filler, 1 to 10 pce of carbon black, 1 to pce of a tackifying resin having a number average molecular mass (Mn) greater than 800 g / mol and an index polymolecularity (Ip) greater than or equal to 2.0; and 100 pce of a plasticizer system comprising 25 to pce of plasticizing oil and 25 to 50 pce of plasticizing resin.

The invention relates to tires and their compositions, in particular as a tread, and more particularly to tires comprising a specific composition for improving the tackiness of the composition before curing.

The ability of rubber compositions to be tacky before curing is an essential property for making tires. In fact, to make the tires, it is necessary to be able to apply the different layers of the tire to each other and that these layers adhere to each other, before the tire is cured, baking which will crosslink the layers together. to others. This tackiness property of the composition before baking is also called "raw tackiness" or "tack" or "green tack".

[003] Recent developments in tires with low rolling resistance have led tire manufacturers to substantially modify the rubber compositions of their tires. This development of low rolling resistance mixtures is generally accompanied by a decrease in raw tack. In fact, the tackifying resins used to increase the raw tackiness are generally accompanied by an increase in hysteresis. The other solution for increasing the sticky raw, by brightening solvent, has the failure to release volatile organic compounds.

Now, the Applicants have shown that a particular tire composition, comprising a specific combination of elastomers, filler and plasticizers makes it possible to have an excellent compromise in performance between the raw tack, the rolling resistance , adhesion and wear.

The invention therefore relates to a tire comprising a rubber composition based on at least 30 to 40 phr of polybutadiene, 45 to 60 phr of styrene butadiene copolymer, the styrene content of which is less than 40% by weight, 0 to 25 pce of polyisoprene, 90 to 150 pce of inorganic reinforcing filler, 1 to 10 pce of carbon black, 1 to 10 pce of a tackifying resin having a number average molecular weight (Mn) greater than 800 g / mol and a polymolecularity index (Ip) greater than or equal to 2.0; and 50 to 100 phr of a plasticizing system comprising from 25 to 50 phr of plasticizing oil and 25 to 50 phr of plasticizing resin.

-2I- Constituents of the composition The rubber compositions according to the invention are based on at least 30 to 40 phr of polybutadiene, 45 to 60 phr of styrene butadiene copolymer whose styrene content is less than 40 % by weight, 0 to 25 phr of polyisoprene, 90 to 150 phr of inorganic reinforcing filler, 1 to 10 phr of carbon black, 1 to 10 phr of a tackifying resin having a number average molecular mass (Mn) greater than 800 g / mol and a polymolecularity index (Ip) greater than or equal to 2.0; and 50 to 100 phr of a plasticizing system comprising from 25 to 50 phr of plasticizing oil and 25 to 50 phr of plasticizing resin.

The expression “composition based on” is understood to mean a composition comprising the mixture and / or the in situ reaction product of the various basic constituents used, some of these constituents being able to react and / or being intended to react between them, at least partially, during the various stages of manufacturing the composition, or during subsequent cooking, modifying the composition as it is prepared at the start. Thus, the compositions as used for the invention may be different in the non-crosslinked state and in the crosslinked state.

In the present description, 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 going from more than a to less than b (i.e. limits a and b excluded) while any range of values designated by the expression from a to b signifies the range of values going from a to b (that is to say including the strict limits a and b).

In the present description and unless expressly indicated otherwise, the glass transition temperature values (Tg) of the compounds is the value as measured according to ASTM D3418.

In the present description, the plasticizing and tackifying resins are hydrocarbon resins, or thermoplastic resins as known to those skilled in the art. In a manner well known to those skilled in the art, the hydrocarbon resins are prepared by polymerization. The manufacture of these resins is described in particular in “Hydrocarbon Resin” by R. Mildenberg, M. Zander, G. Collin and in particular in Chapter 3. This manufacture takes place in four stages, of selection and pre-treatment of feedstocks (washing, distillation) , polymerization of feedstocks (cationic or thermal), neutralization and separation of the resin, which can be done by distillation or stripping. It is described that the synthesis parameters that can impact

-3the characteristics of the resin are inter alia, the nature of the constituents of the feedstock which is polymerized, the type of polymerization process (batch or continuous), the polymerization reaction time, the quantity of initiation reagent and the conditions of separation of the resin. For example, during the separation step, the resin is separated from the unreacted feedstock, made up of molecules of low mass. Conventionally, this separation is carried out by vacuum distillation. The temperature and the pressure therefore make it possible to adjust the minimum molecular weight of the resin. Thus this step makes it possible to modify the molecular mass distribution of the resin. It is thus known to those skilled in the art that adjustments to manufacturing parameters make it possible to obtain various characteristics for the resins prepared. Also commercially, there are many hydrocarbon resins available. These resins can have characteristics, in particular of Mn, Mz and Ip which differ according to the suppliers, and sometimes according to the batch for the same commercial name. Thus, the measurement of the specific parameters of the resins, prepared or commercially available, makes it possible to choose the tackifying resin for the invention, the latter having to present the specific properties of Mn and Ip described in the present application.

The macrostructure (Mw, Mn, Ip and Mz) of the hydrocarbon resins, plasticizers or tackifiers, is determined by steric exclusion chromatography (SEC) on the basis of ISO 16014 standards (Determination of average molecular mass and molecular mass distribution of polymers using size exclusion chromatography), ASTM D5296 (Molecular Weight Averages and molecular weight distribution of polystyrene by High performance size exclusion chromatography), and DIN 55672 (steric exclusion chromatography). For these measurements, the resin sample is dissolved in tetrahydrofuran without antioxidant up to a concentration of 1.5 g / l. The solution is filtered with a Teflon filter with a porosity of 0.45 µm, for example using a disposable syringe fitted with a filter. A volume of 100 μl is injected through a set of steric exclusion chromatography columns. The mobile phase is eluted with a flow rate of 1 ml / min. The columns are thermostatically controlled in an oven at 35 ° C. Detection is ensured by a refractometer thermostatically controlled at 35 ° C. The stationary phase of the columns is based on a divinylbenzene polystyrene gel with controlled porosity. The polymer chains are separated according to the size they occupy when they are dissolved in the solvent: the more they occupy a large volume, the less the pores of the columns are accessible to them and the shorter their elution time. A Moore's calibration curve connecting the logarithm of the molar mass (logM) to

-4 elution time (te) is previously carried out with polystyrene standards, and modeled by a polynomial of order 3: Log (polystyrene molar mass) = a + b te + c te2 + d te3. For the calibration curve, polystyrene standards with narrow molecular distributions are used (polymolecularity index, Ip, less than or equal to

1.1). The molar mass range of these standards ranges from 160 to about 70,000 g / mol. These standards can be grouped into "families" of 4 or 5 standards with an increment of approximately 0.55 in log of M between each. It is possible to use certified standard kits (ISO 13885 and DIN 55672) such as for example the kits of vials from the company PSS (polymer standard service, reference PSS-pskitr11-3), as well as an additional standard PS to Mp = 162 g / mol (Interchim, reference 178952). The number-average molar masses (Mn), mass (Mw), the Mz, and the polydispersity of the resin analyzed are calculated from this calibration curve. This is why, we speak of molar masses relating to a polystyrene calibration. For the calculation of the average masses and the IP, the integration limits for the elution of the product are defined on the chromatogram corresponding to the injection of the sample. We "cut" the refractometric signal defined between the 2 integration terminals every second. For each of the elementary cuts, the elution time ti and the area of the signal from the detector Ai are noted. It is recalled here that: Ip = Mw / Mn with Mw average molecular mass by weight, and Mn molecular mass by number. It is also recalled that the masses Mw, Mn and Mz are average masses calculated according to the formulas below in which Ai is the amplitude of the signal from the refractometric detector corresponding to the mass Mi and to the elution time ti.

2Jï * Afi ^a 'SAHMi

X.-I 2

Σ _ΐΓ , The equipment used for the measurement of SEC is a liquid chromatography chain for example the Alliance 2690 chain from WATERS comprising a pump, a degasser and an injector; a differential refractometer (for example the 2410 refractometer from WATERS), data acquisition and processing software, for example the EMPOWER software from WATERS, a column oven,

-5 example WATERS "columns Heater Module" and 4 columns connected in series in the following order:

Number Mark Molar mass range (g / mol) Length (mm) Diameter internal (mm) Particle size (pm) Designation commercial References (indicative) Columns 1 and 2 Polymer Laboratories 200,400,000 300 7.5 5 MIXED-D PL 11106504 Columns 3 and 4 Polymer Laboratories 200 - 30000 300 7.5 3 MIXED-E PL 11106300

1-1 Diene elastomer The compositions of the invention comprise a specific mixture of several diene elastomers.

By elastomer (or "rubber", the two terms being considered synonymous) of the diene type, it is recalled here that must be understood in known manner one (means one or more) elastomer derived at least in part (ie, a homopolymer or a copolymer) of diene monomers (monomers carrying two carbon-carbon double bonds, conjugated or not).

Diene elastomers can be classified into two categories:

essentially unsaturated or essentially saturated. Generally understood by essentially unsaturated, a diene elastomer derived at least in part from 15 conjugated diene monomers, having a proportion of units or units of diene origin (conjugated dienes) which is greater than 15% (% by moles); This is how diene elastomers such as butyl rubbers or copolymers of dienes and of alpha-olefins of the EPDM type do not enter into the preceding definition and can be qualified in particular as essentially saturated diene elastomers (rate of units d weak or very weak diene origin, always less than 15%). In the category of essentially unsaturated diene elastomers, the term “highly unsaturated diene elastomer” is understood to mean in particular a diene elastomer having a content of units of diene origin (conjugated dienes) which is greater than 50%.

These definitions being given, the rubber composition of the invention comprises, as elastomers, at least 30 to 40 phr of polybutadiene and 45 to 60 phr of styrene butadiene copolymer, the styrene content of which is less than 40% by weight and optionally, 0 to 25 pce of polyisoprene. Preferably, the rubber composition of the invention comprises, as elastomers, at least 30

-6 to 40 phr of polybutadiene and 45 to 60 phr of styrene butadiene copolymer, the styrene content of which is less than 40% by weight and 10 to 25 phr of polyisoprene.

Obviously, each of the polyisoprene, polybutadiene or styrene butadiene copolymer elastomers may be a mixture of several polyisoprenes, polybutadienes or styrene butadiene copolymers respectively.

Preferably, the total rate of polyisoprene, polybutadiene and styrene butadiene copolymer elastomers is 100 phr, that is to say that the composition does not comprise any other elastomer than those previously mentioned.

The butadiene styrene copolymer preferably comprises between 99% and 60% by weight of butadiene units and between 1% and 40% of styrene units.

Preferably also, the styrene butadiene copolymer has a styrene content of less than 30%, preferably less than 20% by weight.

More preferably, said styrene butadiene copolymer has a styrene content in a range ranging from 1% to 20%, preferably from 2 to 17%. in weight.

Butadiene elastomers and styrene butadiene copolymer can 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 the quantities of modifying and / or randomizing agent used . The elastomers can be random, or microsequenced, and be prepared in dispersion or in solution; they can be coupled and / or starred or functionalized with a coupling and / or star-forming or functionalizing agent. The term “function” here preferably means an interactive chemical group with the reinforcing filler of the composition.

As polyisoprene, natural rubber is preferably used, any type of natural rubber can be used, and can optionally be modified or functionalized.

I-2 Reinforcing Filler The composition according to the invention comprises 90 to 150 phr of inorganic reinforcing filler and 1 to 10 phr of carbon black.

As carbon blacks, all carbon blacks are suitable, in particular so-called pneumatic grade blacks. Among the latter, there may be mentioned more particularly the reinforcing carbon blacks of the 100, 200 or 300 series (ASTM grades), such as, for example, the blacks N115, N134, N234, N326, N330, N339, N347, N375, or alternatively, according to the intended applications, the blacks of higher series (for example N660, N683, N772). The carbon blacks could for example already be incorporated into an isoprene elastomer in the form of a masterbatch (see for example applications WO 97/36724 or WO 99/16600).

One can use any type of reinforcing inorganic filler known for its capacity to reinforce a rubber composition which can be used for the manufacture of tires, for example silica, alumina, or alternatively a blend of these two types of filler. . For the purposes of the invention, the reinforcing inorganic filler is preferably silica.

The composition may contain a type of silica or a blend of several silicas. The silica used can be any reinforcing silica known to those skilled in the art, in particular any precipitated or pyrogenic silica having a BET surface as well as a CTAB specific surface, both less than 450 m ² / g, preferably from 30 to 400 m ² / g.

The BET specific surface area (mass area) is determined by gas adsorption using the Brunauer-Emmett-Teller method described in The Journal of the American Chemical Society Vol. 60, page 309, February 1938, more precisely according to French standard NF ISO 9277 of December 1996 [multi-point volumetric method (5 points) - gas: nitrogen - degassing: hour at 160 ° C - relative pressure range p / in: 0.05 0.17], The CTAB specific surface is the external surface determined according to French standard NF T 45-007 of November 1987 (method B).

The silica is preferably a silica with a high specific surface, also commonly called highly dispersible precipitated silica (denoted HDS), having a BET specific surface of between 130 and 400 m ² / g, preferably between 140 and 300 m ² / g, more preferably between 150 and 250 m ² / g. By way of HDS silicas, mention will be made for example of the “Ultrasil 7000” and “Ultrasil 7005” silicas from the company Degussa, the “Zeosil” silicas 1165MP, 1135MP and 1115MP from the company Rhodia, the “Hi-Sil EZ150G” silica the company PPG, the “Zeopol” silicas 8715, 8745 and 8755 from the Huber company, treated precipitated silicas such as for example the aluminum doped silicas described in application EP3053346

-8A-0735088 or silicas with a high specific surface as described in application WO 03/16837.

The physical state in which the reinforcing filler is present is immaterial, whether in the form of powder, microbeads, granules, beads or any other suitable densified form.

For the purposes of the invention, the black content is within a range from 1 to 10 phr, preferably from 2 to 8 phr, and the silica content is within a range from 90 to 150 pce, preferably from 100 to 140 pce, more preferably from 110 to 140 pce. Below 90 phr of silica, the composition could not be sufficiently reinforced while above 150 phr of filler, the composition could be less efficient in rolling resistance.

These compositions may optionally and preferably also contain, in addition to the coupling agents, coupling activators, agents for recovery of inorganic charges or more generally agents for aid in the use which are capable in known manner, thanks to an improvement in the dispersion of the filler in the rubber matrix and to a lowering of the viscosity of the compositions, to improve their ability to be used in the raw state, these agents being for example hydrolysable silanes such as alkylalkoxysilanes, polyols, fatty acids, polyethers, primary, secondary or tertiary amines, hydroxylated or hydrolyzable polyorganosiloxanes.

Polysulfurized silanes, said to be symmetrical or asymmetrical depending on their particular structure, are used in particular, as described for example in applications W003 / 002648 (or US 2005/016651) and W003 / 002649 (or US 2005/016650).

Particularly suitable, without the following definition being limiting, so-called symmetrical polysulphide silanes corresponding to the following general formula (III): (III) Z-A-Sx-A-Z, in which:

- x is an integer from 2 to 8 (preferably from 2 to 5);

- A is a divalent hydrocarbon radical (preferably C1-C18 alkylene groups or C6-C12 arylene groups, more particularly C1-C10, especially C1-C4 alkylene, in particular propylene);

- Z meets one of the formulas below:

9R1 R1 R2 —Si — R1; —If — R2; —If — R2,

R2 R2 R2 in which:

- the radicals R1, substituted or unsubstituted, identical or different from each other, represent a C1-C18 alkyl, C5-C18 cycloalkyl or C6-C18 aryl group (preferably C1-C6 alkyl, cyclohexyl or phenyl groups) , in particular C1-C4 alkyl groups, more particularly methyl and / or ethyl).

- the radicals R2, substituted or unsubstituted, identical or different from each other, represent a C1-C18 alkoxyl or C5-C18 cycloalkoxyl group (preferably a group chosen from C1-C8 alkoxyls and C5-C8 cycloalkoxyles, more preferably still a group chosen from C1-C4 alkoxyls, in particular methoxyl and ethoxyl).

In the case of a mixture of polysulphurized alkoxysilanes corresponding to formula (III) above, in particular the usual mixtures commercially available, the average value of x is a fractional number preferably between 2 and 5, more preferably close to 4. But the invention can also be advantageously implemented, for example with disulphurized alkoxysilanes (x = 2).

By way of examples of polysulphide silanes, mention will be made more particularly of the polysulphides (in particular disulphides, trisulphides or tetrasulphides) of bis- (alkoxyl (C1-C4)) alkyl (C1-C4) silyl-alkyl (C1-C4) ), such as for example bis (3trimethoxysilylpropyl) or bis (3-triethoxysilylpropyl) polysulfides. Among these compounds, bis (3-triethoxysilylpropyl) tetrasulfide, in short TESPT, of formula [(C2H5O) 3Si (CH2) 3S2] 2 or bis- (triethoxysilylpropyl) disulfide, in short TESPD, is used in particular formula [(C2H5O) 3Si (CH2) 3S] 2. Mention will also be made, as preferred examples, of the polysulphides (in particular disulphides, trisulphides or tetrasulphides) of bis (monoalkoxyl (C1-C4) -dialkyl (C1-C4) silylpropyl), more particularly the bis-monoethoxydimethylsilylpropyl tetrasulphide as described in patent application WO 02/083782 (or US 2004/132880).

As coupling agent other than polysulphurized alkoxysilane, there may also be mentioned bifunctional POSs (polyorganosiloxanes) or alternatively hydroxysilane polysulphides (R2 = OH in formula III above) as described in

- 10 patent applications WO 02/30939 (or US 6,774,255) and WO 02/31041 (or US 2004/051210), or also silanes or POS carrying azo-dicarbonyl functional groups, as described for example in patent applications WO 2006/125532, WO 2006/125533, WO 2006/125534.

In the rubber compositions according to the invention, the content of coupling agent is preferably between 5 and 15 phr, more preferably between 7 and 12 phr.

I-3 Crosslinking System In the composition of the invention, any type of crosslinking system known to those skilled in the art can be used for rubber compositions.

Preferably, the crosslinking system is a vulcanization system, that is to say based on sulfur (or a sulfur donor agent) and a primary vulcanization accelerator. To this basic vulcanization system can be added, incorporated during the first non-productive phase and / or during the productive phase as described later, various secondary accelerators or known vulcanization activators such as oxide zinc, stearic acid or equivalent compounds, guanidine derivatives (in particular diphenylguanidine).

Sulfur is used at a preferential rate of between 0.5 and 10 phr, more preferably of between 0.5 and 5 phr, in particular between 0.5 and 3 phr.

The vulcanization system of the composition according to the invention may also include one or more additional accelerators, for example the compounds of the thiuram family, zinc dithiocarbamate derivatives, sulfenamides, guanidines or thiophosphates. Any compound capable of acting as an accelerator for vulcanization of diene elastomers in the presence of sulfur, in particular accelerators of the thiazole type and their derivatives, accelerators of the thiuram type, zinc dithiocarbamates, can be used in particular. These accelerators are more preferably chosen from the group consisting of 2-mercaptobenzothiazyl disulfide (abbreviated MBTS), N-cyclohexyl-2benzothiazyle sulfenamide (abbreviated CBS), N, N-dicyclohexyl-2-benzothiazyle sulfenamide (abbreviated DCBS) , N-tert-butyl-2-benzothiazyle sulfenamide (abbreviated TBBS), N-tert-butyl-2-benzothiazyle sulfenimide (abbreviated TBSI),

-11 zinc dibenzyldithiocarbamate (abbreviated as ZBEC) and mixtures of these compounds. Preferably, a primary accelerator of the sulfenamide type is used.

I-4 Specific hydrocarbon resin - tackifying resin The composition according to the invention comprises a specific hydrocarbon resin, called tackifying resin. This tackifying resin has a number average molecular mass (Mn) greater than 800 g / mol and a polymolecularity index (Ip) greater than or equal to 2.0. The number average molecular mass (Mn) and the polymolecularity index (Ip) are measured by the size exclusion chromatography (SEC) technique, according to the methods defined below.

For the purposes of the invention, this tackifying resin is present at a rate ranging from 1 to 10 phr, preferably from 1 to 8 phr, more preferably from 2 to 6 phr. Below 1 phr, the effect of the resin is not sufficient, while beyond 10 phr the resin could modify the stiffness and glass transition temperature properties of the composition.

Preferably, the tackifying resin has a glass transition temperature, Tg, included in a range from -50 ° C to 100 ° C, more preferably from 40 to 60 ° C. The Tg is measured according to ASTM D3418 (1999).

Preferably, the tackifying resin has a softening point in a range from 0 to 160 ° C, preferably from 90 to 110 ° C. The softening point is measured according to ISO 4625 (Ring and Bail method).

Preferably, the tackifying resin has an Mn greater than 1000 g / mol, more preferably greater than 1200 g / mol.

Preferably, the tackifying resin has an Ip greater than 2.0, more preferably greater than 2.1.

The tackifying resin useful for the needs of the invention can be chosen from natural or synthetic resins. Among the synthetic resins, it can be preferably chosen from aliphatic or aromatic thermoplastic hydrocarbon resins or else of the aliphatic / aromatic type, that is to say based on aliphatic and / or aromatic monomers. As aromatic monomers, for example, styrene, alpha-methylstyrene, ortho-, meta, para-methylstyrene, vinyl-toluene, para-tertiobutylstyrene, methoxystyrenes, chlorostyrenes, vinylmesitylene, divinylbenzene are suitable. vinylnaphthalene, everything

- 12 vinyl aromatic monomer from a C9 cut (or more generally from a C8 to C10 cut). Preferably, the vinyl aromatic monomer is styrene or a vinyl aromatic monomer derived from a C9 cut (or more generally from a C8 to C10 cut). Preferably, the vinyl aromatic monomer is the minority monomer, expressed in molar fraction, in the copolymer considered.

According to a particularly preferred embodiment, the tackifying resin useful for the needs of the invention is chosen from the group consisting of aliphatic hydrocarbon resins and mixtures of the latter and in particular from homopolymer resins or cyclopentadiene copolymers (abbreviated as CPD) or dicyclopentadiene (abbreviated as DCPD), homopolymer resins or C5 cut copolymers and mixtures thereof.

I-5 Combination of plasticizers The composition according to the invention further comprises a combination of plasticizers or plasticizer system. This plasticizer system represents 50 to 100 phr in the composition and comprises from 25 to 50 phr of plasticizing oil and 25 to 50 phr of plasticizing resin. Preferably, the total amount of plasticizer is in a range from 50 to 90 phr, more preferably from 55 to 80 phr, better still, from 55 to 70 phr. Below 50 phr of plasticizer, the composition could be less efficient as regards industrial processability.

1-5-1 Plasticizer Oil The first plasticizer of the plasticizer combination of the composition of the invention is an extension oil (or plasticizer oil) liquid at 20 ° C, called "low Tg", c that is to say which by definition has a Tg of less than -20 ° C, preferably less than -40 ° C.

Any extension oil, whether of an aromatic or non-aromatic nature known for its plasticizing properties with respect to diene elastomers, can be used. At room temperature (20 ° C), these oils, more or less viscous, are liquids (that is to say, substances having the capacity to eventually take the form of their container), by contrast in particular to plasticizing hydrocarbon resins which are by nature solid at room temperature.

The oils chosen from the group consisting of naphthenic oils (low or high viscosity, in particular hydrogenated or not), paraffinic oils, MES oils (Medium Extracted Solvated), TDAE oils (Treated Distillate) are particularly suitable. Aromatic Extracts), mineral oils, vegetable oils, ether plasticizers, ester plasticizers, phosphate plasticizers, sulfonate plasticizers and mixtures of these compounds.

Among the phosphate plasticizers, mention may be made of those which contain between 12 and 30 carbon atoms, for example trioctyl phosphate.

By way of examples of non-aqueous and non-water-soluble ester plasticizers, mention may be made in particular of the compounds chosen from the group consisting of trimellitates, pyromellitates, phthalates, 1,2-cyclohexane dicarboxylates, adipates, azelaates, sebacates, glycerol triesters and mixtures of these compounds. Among the above triesters, mention may in particular be made of glycerol triesters, preferably consisting mainly (for more than 50%, more preferably for more than 80% by weight) of a C18 unsaturated fatty acid, ie say chosen from the group consisting of oleic acid, linoleic acid, linolenic acid and mixtures of these acids. More preferably, whether it is of synthetic or natural origin (case for example of vegetable oils of sunflower or rapeseed), the fatty acid used is constituted for more than 50% by weight, more preferably still for more than 80 % by weight of oleic acid. Such triesters (trioleates) with a high oleic acid content are well known, they have been described for example in application WO 02/088238, as plasticizers in tire treads.

For the purposes of the invention, an oil chosen from the group consisting of vegetable oils whose iodine index in g / 100g is between 90 and 140 is preferably used as plasticizer oil. preferably, a vegetable oil chosen from the group consisting of sunflower oil, rapeseed oil and linseed oil and their mixtures is used. Very preferably, we use sunflower oil.

Preferably, the level of plasticizing oil is in a range from 25 to 45 phr, more preferably from 27 to 40 phr. Below 25 pce of oil or above 50 pce of oil, the composition could be less effective in adhesion on wet ground, by a Tg of the mixture too high or too low.

- 14I-5-2 Plasticizing resin The plasticizer combination also comprises a plasticizing resin, different from the tackifying resin previously described, also sometimes called plasticizing hydrocarbon resin or plasticizing thermoplastic resin, preferably having a lower polymolecularity index (Ip) at 2.0.

In known manner and by definition a resin is a solid at room temperature (23 ° C), as opposed to a liquid plasticizer compound such as an oil. The thermoplastic resin of the invention preferably has a Tg is greater than 20 ° C.

Preferably, the plasticizing resin has at least any of the following characteristics:

a Tg greater than 30 ° C;

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

a polymolecularity index (Ip) of less than 1.8 (reminder: Ip = Mw / Mn with Mw average molecular weight by weight).

More preferably, this plasticizing resin has all of the above preferred characteristics.

The thermoplastic hydrocarbon resins can be aliphatic, or aromatic or else of the aliphatic / aromatic type, that is to say based on aliphatic and / or aromatic monomers. They can be natural or synthetic, based on petroleum or not (if this is the case, also known as petroleum resins).

As aromatic monomers, for example, styrene, alphamethylstyrene, ortho-, meta-, para-methylstyrene, vinyl-toluene, paratertiobutylstyrene, methoxystyrenes, chlorostyrenes, vinylmesitylene, divinylbenzene are suitable. vinylnaphthalene, any vinyl aromatic monomer resulting from a C9 cut (or more generally from a C8 to C10 cut). Preferably, the vinyl aromatic monomer is styrene or a vinyl aromatic monomer derived from a C9 cut (or more generally from a C8 to C10 cut). Preferably, the vinyl aromatic monomer is the minority monomer, expressed in molar fraction, in the copolymer considered.

According to a particularly preferred embodiment, the plasticizing hydrocarbon resin is chosen from the group consisting of resins of homopolymers or copolymers of cyclopentadiene (abbreviated to CPD) or dicyclopentadiene (abbreviated to DCPD), the resins of terpene homopolymers or copolymers, terpene phenol homopolymer or copolymer resins, C5 cut homopolymer or copolymer resins, C9 cut homopolymer or copolymer resins, alpha-methyl homopolymer and copolymer resins styrene and mixtures of these resins. The term terpene groups together here in a known manner the alpha-pinene, beta-pinene and limonene monomers; a limonene monomer is preferably used, a compound which is known in the form of three possible isomers: L-limonene (levorotatory enantiomer), D-limonene (dextrorotatory enantiomer), or else dipentene, racemic of dextrorotatory and levorotatory enantiomers . Among the plasticizing hydrocarbon resins above, there may be mentioned in particular the homo- or copolymer resins of alphapinene, betapinene, dipentene or polylimonene.

The above preferred resins are well known to those skilled in the art and available commercially, for example sold with regard to:

polylimonene resins: by the company DRT under the name Dercolyte L120 (Mn = 625 g / mol; Mw = 1010 g / mol; lp = 1.6; Tg = 72 ° C) or by the company ARIZONA under the name Sylvagum TR7125C ( Mn = 630 g / mol; Mw = 950 g / mol; lp = 1.5; Tg = 70 ° C);

copolymer resins cut C5 / vinyl aromatic, in particular cut C5 / styrene or cut C5 / cut C9: by Neville Chemical Company under the names Super Nevtac 78, Super Nevtac 85 or Super Nevtac 99, by Goodyear Chemicals under the name Wingtack Extra, by Kolon under names Hikorez T1095 and Hikorez T1100, by Exxon under names Escorez 2101 and Escorez 2173;

limonene / styrene copolymer resins: by DRT under the name Dercolyte TS 105 from the company DRT, by ARIZONA Chemical Company under the names ZT115LT and ZT5100.

By way of examples of other preferred resins, mention may also be made of modified phenol alpha-methyl-styrene resins. To characterize these modified phenol resins, it is recalled that an index called hydroxyl index is used in known manner (measured according to ISO standard 4326 and expressed in mg KOH / g). Resins

- 16alpha-methyl-styrene, in particular those modified with phenol, are well known to those skilled in the art and available commercially, for example sold by the company Arizona Chemical under the names Sylvares SA 100 (Mn = 660 g / mol; Ip = 1 , 5; Tg = 53 ° C); Sylvares SA 120 (Mn = 1030 g / mol; Ip = 1.9; Tg = 64 ° C); Sylvares 540 (Mn = 620 g / mol; Ip = 1.3; Tg = 36 ° C; hydroxyl number = 56 mg KOH / g); Silvares 600 (Mn = 850 g / mol; Ip = 1.4; Tg = 50 ° C; hydroxyl number = 31 mg KOH / g).

According to the invention, the level of hydrocarbon resin is in a range from 25 to 50 phr, preferably from 25 to 45 phr, more preferably from 27 to 40 phr, even more preferably from 27 to 35 phr.

I-6 Ratio of Filler and Plasticizer Rates According to a preferred embodiment of the invention, the rates of reinforcing filler and of plasticizer are such that the ratio of the total rate of filler and the total rate of plasticizer is included in a range from 0.8 to 2.3. Below 0.8 the composition could have a lower hardness resulting in a lower performance in vehicle behavior while above 2.3 the composition could have a strong mooney resulting in a lower industrial processability.

Preferably, the ratio of the total charge rate and the total plasticizer rate is in a range from 1 to 2.2 and preferably from 1.4 to 2.2.

I-7 Other possible additives The rubber compositions in accordance with the invention optionally also include all or part of the usual additives usually used in elastomer compositions intended in particular for the manufacture of treads, such as pigments for example , protective agents such as anti-ozone waxes, chemical anti-ozonants, antioxidants, plasticizing agents other than those previously described, anti-fatigue agents, reinforcing resins, acceptors (for example phenol resin Novolac) or methylene donors (e.g. HMT or H3M).

Of course, the compositions according to the invention can be used alone or in blends (i.e., in admixture) with any other rubber composition which can be used for the manufacture of tires.

It goes without saying that the invention relates to the rubber compositions described above, both in the so-called raw or non-crosslinked state (ie, before baking) and in the so-called cooked or crosslinked state, or else vulcanized. (ie, after crosslinking or vulcanization).

II- Preparation of the rubber compositions The compositions are produced in suitable mixers, using two successive preparation phases well known to those skilled in the art: a first working phase or thermo-mechanical kneading (sometimes called phase non-productive) at high temperature, up to a maximum temperature between 110 ° C and 190 ° C, preferably between 130 ° C and 180 ° C, followed by a second phase of mechanical work (sometimes referred to as the productive phase ) at a lower temperature, typically less than 110 ° C., for example between 60 ° C. and 100 ° C., finishing phase during which the crosslinking or vulcanization system is incorporated; such phases have been described for example in applications EP-A0501227, EP-A-0735088, EP-A-0810258, WO00 / 05300 or WO00 / 05301.

The first (non-productive) phase is preferably carried out in several thermomechanical stages. During a first step, elastomers, reinforcing fillers, the combination of plasticizers (and optionally coupling agents and / or other ingredients) are introduced into a suitable mixer such as a conventional internal mixer. exception of the vulcanization system), at a temperature between 20 ° C and 100 ° C and, preferably, between 25 ° C and 100 ° C. After a few minutes, preferably from 0.5 to 2 min and a rise in temperature to 90 ° C to 100 ° C, the other ingredients (that is to say, those which remain if all have not been put at the start) are added all at once or in parts, with the exception of the vulcanization system during mixing ranging from 20 seconds to a few minutes. The total duration of the kneading, in this non-productive phase, is preferably between 2 and 10 minutes at a temperature less than or equal to 180 ° C., and preferably less than or equal to 170 ° C.

After cooling the mixture thus obtained, the vulcanization system is then incorporated at low temperature (typically less than 100 ° C), generally in an external mixer such as a roller mixer; the whole is then mixed (productive phase) for a few minutes, for example between 5 and 15 min.

The final composition thus obtained is then calendered, for example in the form of a sheet or a plate, in particular for characterization in

- 18 laboratory, or even extruded, to form for example a rubber profile used for the manufacture of semi-finished products in order to obtain products such as a tread. These products can then be used for the manufacture of tires, according to techniques known to those skilled in the art.

Vulcanization (or baking) is carried out in known manner at a temperature generally between 130 ° C and 200 ° C, under pressure, for a sufficient time which can vary for example between 5 and 90 min depending in particular on the baking temperature, of the vulcanization system adopted, of the vulcanization kinetics of the composition considered or even of the size of the tire.

III- Use of the composition of the invention The composition according to the invention is preferably used in all or part of the tread of a tire. In a known manner, the tread of a tire is the radially outermost part of the tire, the surface of which is intended to be in contact with the tread surface (i.e., the road). In a known manner also, the tread may itself be made up of several layers, which may have different compositions, the outermost layer being in direct contact with the road while an inner layer may not be in contact with the road when the tire is new, and be in contact with the road either when the tire is used or when it is worn. This type of layer, the inner part of the tread, is sometimes called the base of the tread ("base tread" by difference with "cap tread" in English).

Thus, the invention also relates to a tire whose tread comprises a composition as defined above, more preferably in a radially internal part of said tread, relative to the outermost part.

Preferably, the tire according to the invention will be chosen from tires intended to equip a two-wheeled vehicle, a passenger vehicle, or even a so-called “heavy goods vehicle” (that is to say metro, bus , off-highway vehicles, road transport equipment such as trucks, tractors, trailers), or even airplanes, civil engineering, agrarian or handling equipment.

- 19IV- Examples of embodiment of the invention The examples which follow illustrate the invention without however limiting it.

In the examples which follow, the rubber compositions were produced as described above.

IV-1 Characterization of the examples In the examples, the rubber compositions are characterized before and / or after curing as indicated below.

to

- Raw tights (or tack):

Tack is the ability of an assembly of unvulcanized mixtures to resist pulling stress.

Is used for the measurement of raw tack (tack) a test device is inspired by the probe tack tester (ASTM D2979-95). An Instron traction machine is used comprising a fixed metal jaw and a mobile metal jaw. A first test piece made of a 3mm thick mixing film is bonded to the fixed jaw. A second test piece made of a 3mm thick mixing film is bonded to the movable jaw. The mixing films are bonded to the surface of the metal jaws with a double-sided adhesive (Tesafix® 4970).

For the preparation of the mixing test pieces, the mixing films are obtained by calendering to a thickness of 3 mm. The test pieces are cut using a 1 cm diameter cookie cutter.

The principle of the measurement consists in bringing the two mixing films into contact for 5 seconds by applying a compression force of 40 N. After this contact phase, they are separated by driving the cross member of the machine. traction. The speed of movement of the crosspiece in this tearing phase is 1mm / s. The displacement of the cross member and the force are measured continuously as a function of time during the contact and tear-off phases.

-20 The raw tights result is the measurement of the maximum force (in Newton, N) reached during the tearing. A value of 9 N and above is desirable for the present invention.

- Dynamic properties (after cooking):

According to a first experiment, the dynamic properties G * and tan (ô) max are measured on a viscoanalyzer (Metravib V A4000), according to standard ASTM D 5992 - 96. The response of a sample of vulcanized composition is recorded. (cylindrical specimen 4 mm thick and 400 mm2 in section), subjected to sinusoidal stress in alternating single shear, at the frequency of 10 Hz, at 23 ° C, according to standard ASTM D 1349 - 99. sweep in deformation amplitude peak to peak from 0.1 to 50% (outward cycle), then from 50% to 1% (return cycle). The exploited results are the complex dynamic shear modulus (G *) and the loss factor (tan δ). For the return cycle, the maximum value of tan δ observed (tan (ô) max) is indicated, as well as the difference in complex modulus (AG *) between the values at 0.1% and 50% deformation (effect Payne).

For the values of tan (ô) max at 23 ° C, the lower the value, the lower the composition has a hysteresis and therefore a low rolling resistance, indicating an improved rolling resistance performance. The results are expressed in base 100, on the performance in rolling resistance, that is to say that the value 100 is arbitrarily assigned to a composition, to then compare the tan (ô) max at 23 ° C (c is the hysteresis - and therefore the rolling resistance) of the different solutions tested. The base value 100 is calculated according to the operation: (tan (ô) value max at 23 ° C of the control / tan (ô) value max at 23 ° C of the sample) * 100. In this way, a lower value represents a decrease in adhesion performance (i.e. a higher tan (ô) value at 23 ° C) while a higher value represents a better adhesion performance (c (i.e. a lower tan (ô) value at 23 ° C).

According to a second experiment, the dynamic properties G * and tan (ô) max are measured on a viscoanalyzer (Metravib V A4000), according to standard ASTM D 5992 - 96. The response of a sample of vulcanized composition is recorded. (cylindrical test piece 4 mm thick and 10 mm in diameter), subjected to sinusoidal stress in alternating single shear, at a frequency of 10 Hz, during a temperature sweep from -80 ° C to + 100 ° C with a ramp of + 1.5 ° C / min,

-21 under a maximum stress of 0.7 MPa. The value of the tangent of the loss angle (Tan delta) is then noted in particular at 0 ° C.

For the value of tan (ô) at 0 ° C, the higher the value, the more the composition will allow good wet adhesion. The results are expressed in performance base 100, that is to say that the value 100 is arbitrarily assigned to the best control, to calculate and then compare the tan (ô) at 0 ° C of the different solutions tested. The base value 100 is calculated according to the operation: (tan (ô) value at 0 ° C of the sample / tan (ô) value at 0 ° C of the control) * 100. In this way, a value lower represents a decrease in adhesion performance (i.e. a lower tan (ô) value at 0 ° C) while a higher value represents better adhesion performance (i.e. i.e. a higher tan (ô) value at 0 ° C).

- Tensile tests These tensile tests make it possible to determine the elasticity stresses and the breaking properties. Unless otherwise indicated, they are carried out in accordance with French standard NF T 46-002 of September 1988. The module is measured at second extension (ie, after an accommodation cycle at the rate of extension provided for the measurement itself). nominal secant (or apparent stress, in MPa) at 10% elongation (noted MA10), 100% elongation (noted MA 100) and 300% elongation (noted MA300).

We are particularly interested in the value of MA300, which gives an indication of the reinforcement. The results are expressed in base 100, that is to say that the value 100 is arbitrarily assigned to a composition, to then compare the MA300 of the different solutions tested, the higher the value, the greater the reinforcement.

IV-2 Example 1 The compositions are produced with an introduction of all the constituents on an internal mixer, with the exception of the vulcanization system. The vulcanizing agents (sulfur and accelerator) are introduced on an external mixer at low temperature (the cylinders constituting the mixer being at around 30 ° C).

The examples presented in Table 1 are intended to compare the different properties of a composition according to the invention (C1) to a control composition (T1) corresponding to a solution used before the development of the invention. The properties measured before and after cooking are presented in Table 2.

Table 1

Composition C1 T1 T2 T3 NR (1) 25 25 10 25 BR (2) 30 30 25 30 SBR (3) 45 45 65 45 Black (4) 4 4 4 4 Silica (5) 120 120 120 60 Silane (6) 9.6 9.6 9.6 9.6 Oil (7) 29 29 29 29 Plasticizing resin (8) 29 29 29 29 Total plasticizers 58 58 58 58 Load / Plast Ratio. 2.1 2.1 2.1 1.1 Tackifying resin (9) 4 0 4 4 Protection (10) 5.0 5.0 5.0 5.0 Stearic acid (11) 3.0 3.0 3.0 3.0 DPG (12) 2.1 2.1 2.1 2.1 ZnO (13) 1.5 1.5 1.5 1.5 Accelerator (14) 1.6 1.6 1.6 1.6 Sulfur 1.4 1.4 1.4 1.4

(1) NR: natural rubber (2) BR: polybutadiene to (3) SBR with 15.5% by weight of styrene unit and 24% of unit 1,2 of the butadiene part (Tg = -65 ° C) (4) Black carbon grade ASTM N234 (Cabot company) (5) Silica "Zeosil 1165 MP" from Rhodia type "HDS" (6) Coupling agent: Silane TESPT ("Si69" from Evonik - Degussa) (7) Trioleate of glycerol, sunflower oil at 85% by weight of oleic acid «Lubrirob

Tod 1880 "from Novance (8) C5 / C9 resin" Escorez 2173 "from EXXON (Mn 810 g / mol) (9) Tackifying resin" Escorez 1102 "from EXXON (Mn 1370 g / mol; lp = 2 , 3) (10) N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine (Santoflex 6-PPD) from the company Flexsys and Anti-ozone wax (11) Stearin "Pristerene 4931" from Uniqema (12) Diphenylguanidine "Perkacit DPG" from Flexsys

-23 (13) Zinc oxide of industrial grade - Umicore company (14) N-cyclohexyl-2-benzothiazol-sulfenamide ("Santocure CBS" of the company Flexsys)

Table 2

Composition C1 T1 T1 T1 MA300 performance base 100 100 102 96 76 Tg (5) max at 23 ° C performance base 100 100 104 109 285 Tg (ô) at 0 ° C performance base 100 100 90 95 43 CAC 100 80 89 nm *

* nm: not measured The results show that the compositions of the invention allow a very good raw tack, important for the use of the compositions, while making it possible to conserve and even improve the balance of reinforcement, rolling resistance and grip performance of the tires of the invention.

IV-2 Example 2 The compositions of Example 2 are produced with an introduction of all of the constituents on an internal mixer, with the exception of the vulcanization system. The vulcanizing agents (sulfur and accelerator) are introduced on an external mixer at low temperature (the cylinders constituting the mixer being at around 30 ° C).

The examples presented in Table 3 are intended to compare the different properties of compositions according to the invention (C1 to C4) to a control composition (T3) corresponding to a composition in which the tackifying resin is not in accordance with the criteria of the invention. The raw tack properties are presented in Table 4.

-24Table 3

Composition C1 C2 C3 C4 T3 NR (1) 25 25 25 25 25 BR (2) 30 30 30 30 30 SBR (3) 45 45 45 45 45 Black (4) 4 4 4 4 4 Silica (5) 120 120 120 120 120 Silane (6) 9.6 9.6 9.6 9.6 9.6 Oil (7) 29 29 29 29 29 Plasticizing resin (8) 29 29 29 29 29 Total plasticizers 58 58 58 58 58 Load / Plast Ratio. 2.1 2.1 2.1 2.1 2.1 Tackifying resin A (9) 4 0 0 0 0 Tackifying resin B (9) 0 4 0 0 0 Tackifying resin C (9) 0 0 4 0 0 Tackifying resin D (9) 0 0 0 4 0 Tackifying resin E (9) 0 0 0 0 4 Protection (10) 5.0 5.0 5.0 5.0 5.0 Stearic acid (11) 3.0 3.0 3.0 3.0 3.0 DPG (12) 2.1 2.1 2.1 2.1 2.1 ZnO (13) 1.5 1.5 1.5 1.5 1.5 Accelerator (14) 1.6 1.6 1.6 1.6 1.6 Sulfur 1.4 1.4 1.4 1.4 1.4

(1) NR: natural rubber (2) BR: polybutadiene (3) SBR with 15.5% by weight of styrene unit and 24% of unit 1,2 of the butadiene part (Tg = -65 ° C) (4) Black of carbon Grade ASTM N234 (Cabot company) (5) Silica "Zeosil 1165 MP" from the company Rhodia type "HDS" (6) Coupling agent: Silane TESPT ("Si69" from the company Evonik - Degussa) (7) Trioleate from glycerol, sunflower oil 85% by weight of oleic acid «Lubrirob

Tod 1880 "from Novance (8) C5 / C9 resin" Escorez 2173 "from EXXON (Mn 810 g / mol) (9) See table below

Reference commercial Mn lp Tackifying resin A "Escorez 1102" from EXXON 1370 g / mol 2.3 Tackifying resin B “Piccotac 1105-E” from Eastmann Middleburg 1419 g / mol 2.46 Tackifying resin C "HI-KOREZ A1100" by Kolon Ulsan 866 g / mol 2.0 Tackifying resin D “Quintone A100” by Nippon Zeon 1351 g / mol 2.23 Tackifying resin E Cray Valley Wingtack 98 1028 g / mol 1.6

(10) N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine (Santoflex 6-PPD) from the company Flexsys and Anti-ozone wax (11) Stearin "Pristerene 4931" from the company Uniqema (12 ) Diphenylguanidine “Perkacit DPG” from the company Flexsys (13) Zinc oxide of industrial grade - company Umicore (14) N-cyclohexyl-2-benzothiazol-sulfenamide (“Santocure CBS” from the company Flexsys) to Table 4

Composition C1 C2 C3 C4 T3 CAC 100 103 95 99 68

* nm: not measured. The results show that the compositions of the invention allow a very good raw tack, with a variety of possible tackifying resins, and show that a tackifying resin having an Ip of less than 2.0 does not not allow you to have a good raw tights.

Claims (19)

1. A tire comprising a rubber composition based on at least: 30 to 40 pce of polybutadiene, 45 to 60 phr of styrene butadiene copolymer, the styrene content of which is less than 40% by weight, 0 to 25 pce of polyisoprene, 90 to 150 pce of inorganic reinforcing filler, 1 to 10 pce of carbon black, 1 to 10 phr of a tackifying resin having a number average molecular mass (Mn) greater than 800 g / mol and a polymolecularity index (Ip) greater than or equal to 2.0; 50 to 100 pce of a plasticizer system comprising 25 to 50 pce of plasticizing oil and 25 to 50 pce of plasticizing resin. 2. A tire according to claim 1, in which the composition comprises 10 to 25 phr of polyisoprene. 3. Tire according to any one of the preceding claims, in which said polyisoprene mainly comprises natural rubber. 4. Tire according to any one of the preceding claims, in which said styrene butadiene copolymer has a styrene content of less than 30%, preferably less than 20% by weight. 5. Tire according to any one of the preceding claims, in which the said styrene butadiene copolymer has a styrene content ranging from 1% to 20%, preferably from 2 to 17% by weight. 6. Tire according to any one of the preceding claims, in which the inorganic reinforcing filler is silica. 7. A tire according to the preceding claim, in which the silica has a BET specific surface of between 130 and 400 m ² / g, preferably between 140 and 300 m ² / g. 8. A tire according to any one of the preceding claims in -27which the rate of inorganic reinforcing filler is in a range from 100 to 140 phr, preferably from 110 to 140 phr. 9. A tire according to any one of the preceding claims in which the rate of tackifying resin is in a range from 2 to 6 phr. 10. Tire according to any one of the preceding claims, in which the tackifying resin has a number average molecular mass (Mn) greater than 1000 g / mol, preferably greater than 1200 g / mol. 11. Tire according to any one of the preceding claims, in which the tackifying resin has a polymolecularity index (Ip) greater than 2.0, preferably greater than 2.1. 12. A tire according to any one of the preceding claims in which the total level of plasticizer is in a range from 50 to 90 phr, more preferably from 55 to 80 phr. 13. A tire according to any one of the preceding claims in which the plasticizing oil is chosen from the group consisting of naphthenic oils, paraffinic oils, MES oils, TDAE oils, mineral oils, vegetable oils, plasticizers ethers, ester plasticizers, phosphate plasticizers, sulfonate plasticizers and mixtures of these compounds. 14. Tire according to any one of the preceding claims, in which the plasticizing oil is a vegetable oil whose iodine index in g / 100 g is between 90 and 140, preferably a vegetable oil chosen from the group consisting of sunflower oil, rapeseed and linseed oil and mixtures thereof. 15. Tire according to any one of the preceding claims, in which the level of plasticizing oil is in a range from 25 to 45 phr, more preferably from 27 to 40 phr. 16. Tire according to any one of the preceding claims, in which the plasticizing resin is chosen from the group consisting of homopolymer or copolymer resins of cyclopentadiene or dicyclopentadiene, homopolymer resins or terpene copolymers, terpene phenol copolymer resins, C5 homopolymer or copolymer resins, resins -28 homopolymers or copolymers of C9 cut, homopolymer resins and copolymers of alpha-methyl-styrene and mixtures of these resins. 17. Tire according to any one of the preceding claims, in which the level of plasticizing resin is in a range from 25 to 45 phr, more preferably from 27 to 40 phr. 18. Tire according to any one of the preceding claims, in which the amounts of filler and of plasticizer are such that the ratio of the amount 10 of charge in pce on the amount of plasticizer in pce is within a range from 0.8 to 2.3; preferably from 1 to 2.2. 19. A tire according to any one of the preceding claims in which the tread comprises a composition as defined according to one 15 of claims 1 to 18.