WO2018002539A1 - Tire comprising a composition containing a specific elastomer system - 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 butadiene styrene copolymer, the styrene content of which is less than 40 percent by weight; 0 to 20 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) of more than 800 g/mol and a polydispersity index (Ip) of at least 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

 PNEUMATIC COMPRISING A COMPOSITION COMPRISING A SPECIFIC SYSTEM OF ELASTOMERS

[001] The invention relates to tires and their compositions, in particular tread, and more particularly to tires comprising a specific composition for improving the tack of the composition before firing.

 [002] The ability of rubber compositions to be tacky before baking is an indispensable property for the manufacture of tires. Indeed, to make the tires, it is necessary to be able to apply the different layers of the tire on each other and that these layers adhere to each other, before the baking of the tire, which will combine by crosslinking the layers some to others. This stickiness property of the composition before firing, is also called "raw tack" or "tack" or "green tack".

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

 [004] At present, the Applicant has shown that a particular composition in a tire, comprising a specific combination of elastomers, filler and plasticizers makes it possible to have an excellent compromise of performance between the raw tack, the rolling resistance , adhesion and wear.

[005] 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 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 a polymolecularity index (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. I- 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% by weight. polyisoprene composition, 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) of greater than 800 g / mol and an index 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.

 By the term "composition based on" is meant a composition comprising the mixture and / or the reaction product in situ 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 phases of manufacture of the composition, or during the subsequent firing, modifying the composition as it was initially prepared. Thus, the compositions as implemented for the invention may be different in the uncrosslinked state and in the crosslinked state.

 [008] In the present description, unless otherwise expressly indicated, all the percentages (%) indicated are percentages by weight. 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).

[009] In the present description and unless expressly indicated otherwise, the glass transition temperature (Tg) values 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. As is 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 Chapter 3. This manufacture takes place in four stages, 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 the characteristics of the resin are among others, the nature of the constituents of the feedstock that is polymerized, the type of polymerization process (Batch or continuous), the polymerization reaction time, the quantity of initiating reagent and the conditions of separation of the resin. For example, during the separation step, the resin is separated from the unreacted feedstock, consisting of low mass molecules. This separation is conventionally carried out by vacuum distillation. The temperature and the pressure thus make it possible to adjust the minimum molecular mass of the resin. Thus, this step makes it possible to modify the molecular weight distribution of the resin. It is thus known to those skilled in the art that adjustments in manufacturing parameters make it possible to obtain various characteristics for the resins prepared. In commerce also, there are many hydrocarbon resins available. These resins may 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 denomination. 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 exhibit the specific properties of Mn and Ip described in the present application.

The macrostructure (Mw, Mn, Ip and Mz) of hydrocarbon resins, plasticizing or tackifying, is determined by size 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 (size exclusion chromatography). For these measurements, the resin sample is solubilized in tetrahydrofuran without antioxidant to a concentration of 1.5 g / l. The solution is filtered with a Teflon filter with a porosity of 0.45 μηη, for example using a disposable syringe fitted with a filter. A volume of 100 μΙ is injected through a set of size 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. The detection is ensured by a refractometer thermostated at 35 ° C. The stationary phase of the columns is based on a divinylbenzene polystyrene gel with controlled porosity. Polymer chains are separated according to the size they occupy when they are solubilized in the solvent: the more they occupy a large volume, the less accessible the pores of the columns and their elution time is low. A Moore calibration curve connecting the logarithm of the molar mass (logM) to the elution time (te) is previously performed with polystyrene standards, and modeled by a polynomial of order 3: Log (molar mass of polystyrene) = a + b te + c te2 + d te3. For the standard curve polystyrene standards with narrow molecular distributions (polymolecularity index, Ip, less than or equal to 1.1) are used. The molar mass range of these standards ranges from 160 to about 70,000 g / mol. These standards can be grouped by "families" of 4 or 5 standards having 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 the PSS (polymer standard service) vial kits, reference PSS-pskitr1 l-3, and an additional standard PS of Mp = 162. g / mol (Interchim, reference 178952). The average molar masses (Mn), by 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 relative to a polystyrene calibration. For the calculation of the average masses and the Ip, one defines on the chromatogram corresponding to the injection of the sample the limits of integration of the elution of the product. The refractometric signal defined between the 2 integration terminals is "cut" every second. For each of the "elementary cuts", the elution time ti and the signal area of the detector Ai are recorded. It is recalled here that: Ip = Mw / Mn with Mw weight average molecular weight, and Mn molecular mass by number. It is also recalled that the masses Mw, Mn and Mz are average masses calculated from the formulas below in which Ai is the amplitude of the signal of the refractometric detector corresponding to the mass Mi and the elution time ti.

The equipment used for the SEC measurement is a liquid chromatography chain, for example the WATERS Alliance 2690 chain comprising a pump, a degasser and an injector; a differential refractometer (for example the WATERS refractometer 2410), data acquisition and processing software, for example WATERS WATOWER software, a column oven, for example WATERS "columns Heater Module" and 4 columns mounted in series in the following order :

 5

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

 The diene elastomers can be classified in two categories: 5 "essentially unsaturated" or "essentially saturated". The term "essentially unsaturated" is generally understood to mean a diene elastomer derived at least in part from conjugated diene monomers, having a level of units or units of diene origin (conjugated dienes) which is greater than 15% (mol%); Thus, diene elastomers such as butyl rubbers or copolymers of dienes 0 and alpha-olefins EPDM type do not fall within the above definition and may be particularly described as "substantially saturated" diene elastomers (rate low or very low diene origin, always less than 15%). In the category of "essentially unsaturated" diene elastomers, the term "highly unsaturated" diene elastomer is particularly understood to mean a diene elastomer having a diene origin ratio (conjugated dienes) of greater than 50%.

Given these definitions, 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 whose styrene content is less than 40%. in weight and optionally, 0 to 25 phr of polyisoprene. Preferably, 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 whose styrene content is less than 40% by weight and to 25 phr of polyisoprene.

Of course, 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 content of polyisoprene elastomers, polybutadiene and styrene-butadiene copolymer is 100 phr, that is to say that the composition does not include any other elastomer than those mentioned above.

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

 [0020] Also preferably, 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 ranging from 1% to 20%, preferably from 2 to 17%. in weight.

 The butadiene elastomers and styrene butadiene copolymer 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 the amounts of modifying and / or randomizing agent used. . The elastomers may be random, or microsequenced, and may be prepared in dispersion or in solution; they may be coupled and / or starred or functionalized with a coupling agent and / or starring or functionalization. By function is meant here preferably a chemical group interactive with the reinforcing filler of the composition.

 As polyisoprene is preferably used natural rubber, any type of natural rubber is usable, and may 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 are suitable for all carbon blacks, including so-called pneumatic grade blacks. Among these, the reinforcing carbon blacks of the 100, 200 or 300 series (ASTM grades), for example blacks N 15, N 134, N 234, N 326, N330, N 339, N 347 or N375, or else, according to the targeted 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 WO 97/36724 or WO 99/16600).

 Can be used any type of reinforcing inorganic filler known for its ability to strengthen a rubber composition used for the manufacture of tires, for example silica, alumina, or a blend of these two types of load . 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 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.

 The specific surface ("mass area") BET 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 the French standard NF ISO 9277 of December 1996 (multipoint volumetric method (5 points) - gas: nitrogen - degassing: 1 hour at 160 ° C - relative pressure range p / po: 0.05 to 0.17]. The CTAB specific surface is the external surface determined according to the French standard NF T 45-007 of November 1987 (method B).

The silica is preferably a high surface area silica, also commonly called highly dispersible precipitated silica (denoted "HDS"), having a BET specific surface area 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. As silicas HDS, there may be mentioned for example the silicas "Ultrasil 7000" and "Ultrasil 7005" from the company Degussa, the silicas "Zeosil" 1 165MP, 1 135MP and 1 1 15MP from the company Rhodia, silica "Hi- Sil EZ150G "from the company PPG, silicas "Zeopol" 8715, 8745 and 8755 from the company Huber, treated precipitated silicas such as, for example, the "aluminum doped" silicas described in application EP-A-0735088 or the silicas with a high surface area as described in US Pat. WO 03/16837.

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

 For the purposes of the invention, the level of black is in a range from 1 to 10 phr, preferably from 2 to 8 phr, and the silica content is in a range from 90 to 150. preferably from 100 to 140 phr, more preferably from 10 to 140 phr. Below 90 phr of silica, the composition may not be sufficiently reinforced while above 150 phr of the load, the composition may be less effective in rolling resistance.

 These compositions may optionally and preferably also contain, in addition to the coupling agents, coupling activators, inorganic charge-covering agents or, more generally, processing aid agents that are capable in a known manner, by virtue of their to improve the dispersion of the filler in the rubber matrix and to lower 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, polyols, fatty acids, polyethers, primary, secondary or tertiary amines, hydroxylated or hydrolysable polyorganosiloxanes.

 In particular, polysulfide silanes, called "symmetrical" or "asymmetrical" according to their particular structure, are used, as described for example in the applications WO03 / 002648 (or US 2005/016651) and WO03 / 002649 (or US 2005 / 016650).

 In particular, the following definition is not limiting, so-called "symmetrical" polysulfide silanes having the following general formula (III):

(III) Z - A - Sx - A - Z, wherein:

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

A is a divalent hydrocarbon radical (preferably C 1 -C 18 alkylene groups or C 6 -C 12 arylene groups, more particularly C 1 -C 10 alkylenes, in particular C 1 -C 4 alkylenes, in particular propylene); Z is one of the following formulas:

R1 R1 R2

 -Si-R1; - Si- R2; - Si- R2,

 R2 R2 in which:

 the radicals R1, substituted or unsubstituted, which are identical to or different from one another, represent a C1-C18 alkyl, C5-C18 cycloalkyl or C6-C18 aryl group;

(preferably C 1 -C 6 alkyl, cyclohexyl or phenyl groups, especially C 1 -C 4 alkyl groups, more particularly methyl and / or ethyl).

 the radicals R2, substituted or unsubstituted, which are identical to or different from each other, represent a C 1 -C 18 alkoxyl or C 5 -C 18 cycloalkoxyl group (preferably a group chosen from C 1 -C 8 alkoxyls and C 5 -C 8 cycloalkoxyls, plus preferably still another group chosen from C 1 -C 4 alkoxyls, in particular methoxyl and ethoxyl).

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

 By way of examples of polysulphurized silanes, mention may be made more particularly of polysulfides (in particular disulfides, trisulphides or tetrasulfides) of bis (C 1 -C 4 alkoxyl) -alkyl (C 1 -C 4) alkyl-silyl (C 1 -C 4) )), such as polysulfides of bis (3-trimethoxysilylpropyl) or bis (3-triethoxysilylpropyl). Among these compounds, bis (3-triethoxysilylpropyl) tetrasulfide, abbreviated TESPT, of formula [(C2H50) 3Si (CH2) 3S2] 2 or bis (triethoxysilylpropyl) disulfide, abbreviated as TESPD, is especially used. formula [(C2H50) 3Si (CH2) 3S] 2. Mention may also be made, by way of preferred examples, of polysulfides (in particular disulfides, trisulphides or tetrasulfides) of bis- (monoalkoxyl (C1 -C4) -dialkyl (C1 -C4) silylpropyl), more particularly bis-monoethoxydimethylsilylpropyl tetrasulfide, as described above. in the patent application WO 02/083782 (or US 2004/132880).

As a coupling agent other than polysulfurized alkoxysilane, mention may also be made of bifunctional POS (polyorganosiloxanes) or polysulfides hydroxysilane (R2 = OH in the formula III above) as described in patent applications WO 02/30939 (or US 6,774,255) and WO 02/31041 (or US 2004/051210), or silanes or POS bearing 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.

1-3 Crosslinking system

 In the composition of the invention, one can use any type of crosslinking system known to those skilled in the art 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 known secondary accelerators or vulcanization activators such as 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 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 comprise one or more additional accelerators, for example the compounds of the thiuram family, zinc dithiocarbamate derivatives, sulfenamides, guanidines or thiophosphates. In particular, any compound capable of acting as a vulcanization accelerator for diene elastomers in the presence of sulfur, in particular thiazole type accelerators and their derivatives, thiuram type accelerators, zinc dithiocarbamates, may be used in particular. These accelerators are more preferably selected from the group consisting of 2-mercaptobenzothiazyl disulfide (abbreviated "MBTS"), N-cyclohexyl-2-benzothiazyl sulfenamide (abbreviated "CBS"), N, N-dicyclohexyl-2-benzothiazyl sulfenamide (abbreviated "DCBS"), N-tert-butyl-2-benzothiazyl sulfenamide (abbreviated "TBBS"), N-tert-butyl-2-benzothiazylsulfenimide (abbreviated "TBSI"), 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 weight (Mn) greater than 800 g / mol and a polymolecularity index (Ip) greater than or equal to 2.0. The number average molecular weight (Mn) and the polymolecularity index (Ip) are measured by the steric exclusion chromatography (SEC) technique, according to the methods defined below.

 For the purposes of the invention, this tackifying resin is present at a level 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 properties of stiffness and glass transition temperature of the composition.

 Preferably, the tackifying resin has a glass transition temperature, Tg, in a range from -50 ° C to 100 ° C, more preferably from 40 to 60 ° C. 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 a Mn greater than 1000 g / mol, more preferably greater than 1200 g / mol.

[0048] Preferably, the tackifying resin has an Ip greater than 2.0, more preferably greater than 2.1.

The tackifying resin useful for the purposes of the invention may be chosen from natural or synthetic resins. Among the synthetic resins it may be preferentially chosen from aliphatic or aromatic thermoplastic hydrocarbon resins or else from the aliphatic / aromatic type, that is to say based on aliphatic and / or aromatic monomers. Suitable aromatic monomers are, for example, styrene, alpha-methylstyrene, ortho-, meta-, para-methylstyrene, vinyl-toluene, para-tert-butylstyrene, methoxystyrenes, chlorostyrenes, vinylmesitylene, divinylbenzene, vinylnaphthalene, any vinylaromatic monomer resulting from a C9 cut (or more generally from a C8 to C10 cut). Preferably, the vinylaromatic monomer is styrene or a vinylaromatic monomer derived from a C9 cut (or more generally from a C8 to C10 cut). Preferably, the vinylaromatic monomer is the minor monomer, expressed as a mole fraction, in the copolymer under consideration.

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

1-5 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 level of plasticizer is in a range from 50 to 90 phr, more preferably from 55 to 80 phr, more preferably from 55 to 70 phr. Below 50 phr of plasticizer, the composition could be less efficient in terms of industrial processability.

1-5-1 Plasticizing Oil

 The first plasticizer of the plasticizer combination of the composition of the invention is an oil extension (or plasticizing oil) liquid at 20 ° C, said to "low Tg", that is to say, which by definition has a Tg lower than -20 ° C, preferably lower than -40 ° C.

Any extender oil, whether of aromatic or non-aromatic nature known for its plasticizing properties vis-à-vis diene elastomers, is usable. At ambient temperature (20 ° C), these oils, more or less viscous, are liquids (that is to say, as a reminder, substances having the ability to eventually take the shape of their container), as opposed in particular to hydrocarbon plasticizing resins which are inherently solid at room temperature. Particularly suitable oils selected from the group consisting of naphthenic oils (low or high viscosity, including hydrogenated or not), paraffinic oils, MES oils (Medium Extracted Solvates), TDAE oils (Treated Distillate Aromatic Extracts) ), mineral oils, vegetable oils, ethers plasticizers, ester plasticizers, phosphate plasticizers, sulphonate plasticizers and mixtures of these compounds.

 Among the phosphate plasticizers include those containing 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 compounds selected from the group consisting of trimellitates, pyromellitates, phthalates, 1,2-cyclohexane dicarboxylates, adipates, azelaic acid esters, sebacates, glycerol triesters and mixtures of these compounds. Among the triesters above, mention may be made in particular of glycerol triesters, preferably consisting mainly (for more than 50%, more preferably for more than 80% by weight) of a C18 unsaturated fatty acid, that is, that is to say chosen from the group consisting of oleic acid, linoleic acid, linolenic acid and mixtures of these acids. More preferably, whether of synthetic or natural origin (for example vegetable oils of sunflower or rapeseed), the fatty acid used is more than 50% by weight, more preferably still more than 80% by weight. % 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.

 For the purposes of the invention is preferably used as a plasticizing oil an oil selected from the group consisting of vegetable oils whose iodine value in g / 100g is between 90 and 140. So Preferably, a vegetable oil selected from the group consisting of sunflower oil, rapeseed oil and linseed oil and mixtures thereof is used. Very preferably, sunflower oil is used.

Preferably, the level of plasticizing oil is in a range from 25 to 45 phr, more preferably from 27 to 40 phr. Below 25 phr of oil or above 50 phr of oil, the composition could be less effective in adhesion on wet ground, with a Tg of the mixture too high or too low. I-5-2 Plasticizing resin

 The plasticizer combination also comprises a plasticizing resin, different from the tackifying resin described above, also sometimes called plasticizing hydrocarbon resin or plasticizing thermoplastic resin, preferably having a polymolecularity index (Ip) of less than 2.0.

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

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

 a Tg greater than 30 ° C;

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

 a polymolecularity index (Ip) of less than 1.8 (recall: Ip = Mw / Mn with

MW weight average molecular weight).

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

 The thermoplastic hydrocarbon resins may be aliphatic, or aromatic or 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).

Examples of suitable aromatic monomers are styrene, alpha-methylstyrene, ortho-, meta-, para-methylstyrene, vinyl-toluene, para-tertiarybutylstyrene, methoxystyrenes, chlorostyrenes, vinylmesitylene, divinylbenzene, vinylnaphthalene, any vinylaromatic monomer from a C9 cut (or more generally from a C8 to C10 cut). Preferably, the vinylaromatic monomer is styrene or a vinylaromatic monomer derived from a C9 cut (or more generally from a C8 to C10 cut). Preferably, the vinylaromatic monomer is the minor monomer, expressed as a mole fraction, in the copolymer under consideration. According to a particularly preferred embodiment, the plasticizing hydrocarbon resin is selected from the group consisting of homopolymer resins or copolymers of cyclopentadiene (abbreviated CPD) or dicyclopentadiene (abbreviated DCPD), homopolymer resins or terpene copolymers, terpene phenol homopolymer or copolymer resins, homopolymer resins or C5 cutting copolymers, C9 homopolymer or copolymer resins, alpha-methyl-styrene homopolymer and copolymer resins, and mixtures of these resins. The term "terpene" here combines 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. . Among the above-mentioned hydrocarbon plasticizing resins, there may be mentioned resins of homo- or copolymers of alphapinene, betapinene, dipentene or polylimonene.

 The preferred resins above are well known to those skilled in the art and commercially available, 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 ARIZONA under the name " Sylvagum TR7125C "(Mn = 630 g / mol, Mw = 950 g / mol, lp = 1.5, Tg = 70 ° C);

 C5 / vinylaromatic cut copolymer resins, in particular C5 / styrene cut or C5 cut / C9 cut: by Neville Chemical Company under the names "Super Nevtac 78", "Super Nevtac 85" or "Super Nevtac 99", by Goodyear Chemicals under denomination "Wingtack Extra", by Kolon under the names "Hikorez T1095" and "Hikorez T1 100", by Exxon under the 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 "ZT1 15LT" and "ZT5100".

As examples of other preferred resins, mention may also be made of phenol-modified alpha-methyl-styrene resins. To characterize these phenol-modified resins, it is recalled that a so-called "hydroxyl number" index (measured according to ISO 4326 and expressed in mg KOH / g) is used in a known manner. Resins alpha-methyl-styrene, in particular those modified phenol, are well known to those skilled in the art and commercially available, 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, more preferably from 27 to 35 phr.

1-6 Load and Plasticizer Ratio Report

 According to a preferred embodiment of the invention, the levels of reinforcing filler and plasticizer are such that the ratio of the total charge rate and the total plasticizer content is in a range from 0.8 to 2. 3. Below 0.8 the composition may have a lower hardness leading to a lower performance of vehicle behavior while above 2.3 the composition could have a strong mooney resulting in less industrial processability.

 Preferably, the ratio of the total charge rate and the total plasticizer content 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, for example, pigments, protective agents such as anti-ozone waxes, chemical antiozonants, anti-oxidants, plasticizers other than those previously described, anti-fatigue agents, reinforcing resins, acceptors (for example Novolac phenolic resin) or methylene donors (for example). example HMT or H3M).

Of course, the compositions according to the invention can be used alone or in cutting (ie, mixed) with any other rubber composition used for the manufacture of tires. It goes without saying that the invention relates to the previously described rubber compositions both in the so-called "raw" or uncrosslinked state (ie, before cooking) in the so-called "cooked" or crosslinked state, or still vulcanized (ie, after crosslinking or vulcanization).

II- Preparation of rubber compositions

 The compositions are 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 (sometimes called "non-productive" phase) to high temperature, up to a maximum temperature between 1 10 ° C and 190 ° C, preferably between 130 ° C and 180 ° C, followed by a second phase of mechanical work (sometimes called "productive" phase) to lower temperature, typically less than 1 10 ° C, for example between 60 ° C and 100 ° C, finishing phase during which is incorporated the crosslinking system or vulcanization; such phases have been described, for example, in EP-A-0501227, EP-A-0735088, EP-A-0810258, WO00 / 05300 or WO00 / 05301.

 The first phase (non-productive) is preferably carried out in several thermomechanical steps. In a first step, the elastomers, the reinforcing fillers, the combination of plasticizers (and optionally the coupling agents and / or other ingredients at the same time) are introduced into a suitable mixer such as a conventional internal mixer. exception of the vulcanization system), at a temperature of 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 (ie, those that remain if all were not put initially) are added at once or in portions, except for the vulcanization system during mixing ranging from 20 seconds to a few minutes. The total mixing time, in this non-productive phase, is preferably between 2 and 10 minutes at a temperature of 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 below 100 ° C), generally in an external mixer such as a roll mill; 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 a characterization at laboratory, or extruded, to form for example a rubber profile used for the manufacture of semi-finished to obtain products such as a tread. These products can then be used for the manufacture of tires, according to the techniques known to those skilled in the art.

The vulcanization (or baking) is conducted in a known manner at a temperature generally between 130 ° C and 200 ° C, under pressure, for a sufficient time which may vary for example between 5 and 90 min depending in particular on the cooking temperature, the vulcanization system adopted, the kinetics of vulcanization of the composition in question or 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 known manner, the tread of a tire is the portion of the tire, radially outermost, whose surface is intended to be in contact with the running surface (i.e., the road). In a manner also known, the tread may itself consist of several layers, which may have different compositions, the outermost layer being in direct contact with the road while a more interior layer may not be in contact with the road. contact with the road when the tire is new, and be in contact with the road either during the use of the tire or during its wear. This type of layer, of the inner part of the tread, is sometimes called the base 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 inner portion of said tread, relative to the outermost portion.

Preferably, the tire according to the invention will be selected from tires intended to equip a two-wheeled vehicle, a passenger vehicle, or a vehicle called "heavyweight" (that is to say, subway, bus , off-the-road vehicles, road transport vehicles such as trucks, tractors, trailers), or aircraft, civil engineering, agrarian, or handling equipment. IV-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 previously.

IV-1 Characterization of examples

 In the examples, the rubber compositions are characterized before and / or after cooking as indicated below.

- Raw tights (or tack):

 The tack is the ability of an assembly of unvulcanized mixtures to withstand a pulling stress.

 For the measurement of raw tack (tack), a test device is inspired by the probe tack tester (ASTM D2979-95). An Instron traction machine with a fixed metal jaw and a movable metal jaw is used. A first test piece consisting of a 3mm thick mixing film is glued to the fixed jaw. A second specimen consisting of a 3mm thick mixing film is glued to the movable jaw. Mixing films are glued to the surface of the metal jaws with a double-sided adhesive (Tesafix® 4970).

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

The principle of the measurement is to bring the two mixing films into contact for 5 seconds by applying a compressive force of 40 N. After this contact phase, they are separated by driving the cross member of the traction machine. . The speed of movement of the crossbar in this phase of tearing is 1 mm / s. Transverse displacement and force are measured continuously as a function of time during the contact and tear phases. The result of raw adhesive is the measurement of the maximum force (in Newton, N) reached during 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 (5) max are measured on a viscoanalyzer (Metravib V A4000), according to the ASTM D 5992 - 96 standard. The response of a sample of vulcanized composition is recorded. (cylindrical test specimen 4 mm thick and 400 mm 2 in section) subjected to a sinusoidal stress in alternating simple shear at a frequency of 10 Hz at 23 ° C., according to ASTM D 1349-99. peak-to-peak deformation amplitude scan from 0.1 to 50% (forward cycle), then from 50% to 1% (return cycle). The results exploited 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 (δ) max) and the complex modulus difference (AG ^* ) between the values at 0.1% and at 50% of deformation (effect Payne).

For values of tan (5) max at 23 ° C, the lower the value, the lower the composition has a low hysteresis and therefore a low rolling resistance, indicating improved rolling resistance performance. The results are expressed in base 100, on the rolling resistance performance, that is to say that the value 100 is arbitrarily assigned to a composition, to then compare the tan (5) max at 23 ° C. (c). ie the hysteresis - and thus the rolling resistance) of the different solutions tested. The value in base 100 is calculated according to the operation: (value of tan (5) max at 23 ° C of the control / value of tan (5) max at 23 ° C of the sample) ^* 100. In this way, a lower value represents a decrease in adhesion performance (i.e., a tan (5) max value at 23 ° C higher) while a higher value represents a better adhesion performance (c that is, a value of tan (5) max at 23 ° C lower).

According to a second experiment, the dynamic properties G ^* and tan (5) max are measured on a viscoanalyzer (Metravib V A4000), according to the ASTM D 5992 - 96 standard. The response of a sample of vulcanized composition is recorded. (cylindrical specimen 4 mm thick and 10 mm in diameter) subjected to a sinusoidal stress in alternating simple shear, at a frequency of 10 Hz, during a temperature sweep of -80 ° C to + 100 ° C with a ramp of + 1.5 ° C / min, under a maximum stress of 0.7 MPa. The value of the tangent of the angle of loss (Tan delta) is then raised especially at 0 ° C.

For the value of tan (5) 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 (5) at 0 ° C. of the different solutions tested. The value in base 100 is calculated according to the operation: (value of tan (5) at 0 ° C of the sample / value of tan (5) at 0 ° C of the control) ^* 100. In this way, a value lower is a decrease in adhesion performance (i.e., a tan value (5) at 0 ° C lower) while a higher value represents a better adhesion performance (ie that is, a tan value (5) at 0 ° C higher).

- Traction tests

These tensile tests make it possible to determine the elastic stresses and the properties at break. Unless otherwise indicated, they are carried out in accordance with the French standard NF T 46-002 of September 1988. A second elongation (Le., After a cycle of accommodation at the extension rate provided for the measurement itself) is measured. Nominal secant modulus (or apparent stress, in MPa) at 10% elongation (denoted MA10), 100% elongation (denoted MA 100) and 300% elongation (denoted MA300).

 We are particularly interested in the value of the 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 is important.

IV-2 Example 1

The compositions are manufactured 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 constituent rolls of the mixer being at about 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

(1) NR: natural rubber

 (2) BR: polybutadiene

(3) SBR with 15.5% by weight of styrene unit and 24% of 1,2 part of butadiene (Tg = -65 ° C)

 (4) ASTM N234 Grade Carbon Black (Cabot Company)

 (5) "Zeosil 1,165 MP" silica of Rhodia type "HDS"

 (6) Coupling agent: Silane TESPT ("Si69" from Evonik-Degussa) (7) Glycerol trioleate, sunflower oil 85% by weight of oleic acid "Lubrirob Tod 1880" from Novance

 (8) C5 / C9 resin "Escorez 2173" from EXXON company (Mn 810 g / mol)

 (9) EXXON Escorez 1 102 Tackifying Resin (Mn 1370 g / mol, lp = 2.3)

(10) N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine (Santoflex 6-PPD) from Flexsys and Anti-Ozone Wax

 (1 1) Stearin "Pristerene 4931" from the company Uniqema

(12) Diphenylguanidine "Perkacit DPG" from Flexsys (13) Industrial Grade Zinc Oxide - Umicore Company

 (14) N-cyclohexyl-2-benzothiazol sulfenamide ("Santocure CBS" from the company Flexsys)

Table 2

 * nm: not measured

The results show that the compositions of the invention allow a very good sticky raw, important for the implementation of the compositions, while allowing to maintain and even improve the balance of performance reinforcement, strength to the rolling and adhesion of the tires of the invention.

 IV-2 Example 2

The compositions of Example 2 are manufactured 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 constituent rolls of the mixer being at about 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 whose tackifying resin is not according to the criteria of the invention. The properties of raw tights are presented in Table 4. Table 3

(1) NR: natural rubber

 (2) BR: polybutadiene

(3) SBR with 15.5% by weight of styrene unit and 24% of 1,2 part of butadiene (Tg = -65 ° C)

 (4) ASTM N234 Grade Carbon Black (Cabot Company)

 (5) "Zeosil 1,165 MP" silica of Rhodia type "HDS"

 (6) Coupling agent: Silane TESPT ("Si69" from Evonik-Degussa) (7) Glycerol trioleate, sunflower oil 85% by weight of oleic acid "Lubrirob Tod 1880" from Novance

 (8) C5 / C9 resin "Escorez 2173" from EXXON company (Mn 810 g / mol)

(9) See table below Reference

 mn

 Ip commercial

 "Escorez 1,102"

 Tackifying resin A 1370 g / mol 2.3

 EXXON

 "Piccotac 1 105-E"

 of society

 Tacking resin B 1419 g / mol 2.46

 Eastman

 Middleburg

 "HI-KOREZ A-

Company Tackifying Resin C 1 100 "866 g / mol 2.0

 Kolon Ulsan

 "Quintone A100"

 Nippon company tackifying resin D 1351 g / mol 2.23

 Zeon

 "Wingtack 98" of

 T tacking resin company Cray 1028 g / mol 1, 6

 Valley

(10) N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine (Santoflex 6-PPD) from Flexsys and Anti-Ozone Wax

 (1 1) Stearin "Pristerene 4931" from the company Uniqema

(12) Diphenylguanidine "Perkacit DPG" from Flexsys

 (13) Industrial Grade Zinc Oxide - Umicore Company

 (14) N-cyclohexyl-2-benzothiazol sulfenamide ("Santocure CBS" from the company Flexsys)

Table 4

 * nm: not measured

 The results show that the compositions of the invention allow a very good sticky raw, with a variety of possible tackifying resins, and show that a tackifying resin having an IP less than 2.0 does not allow to have a good sticky bareback.

Claims

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 a polymolecularity index (Ip) greater than or equal to 2.0;  50 to 100 phr of a plasticizer system comprising 25 to 50 phr of plasticizing oil and 25 to 50 phr of plasticizing resin. 2. A tire according to claim 1, wherein the composition comprises 10 to 25 phr of polyisoprene. 3. A tire according to any one of the preceding claims, wherein said polyisoprene comprises predominantly natural rubber. 4. A tire according to any one of the preceding claims wherein said styrene-butadiene copolymer has a styrene content of less than 30%, preferably less than 20% by weight. 5. A tire according to any one of the preceding claims wherein said styrene butadiene copolymer has a styrene content in a range from 1% to 20%, preferably 2 to 17% by weight. A tire according to any one of the preceding claims wherein the inorganic reinforcing filler is silica. 7. A tire according to the preceding claim wherein the silica has a BET specific surface area 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 wherein the level of inorganic reinforcing filler is in a range from 100 to 140 phr, preferably from 1 to 140 phr. 9. A tire according to any one of the preceding claims wherein the level of tackifying resin is in a range from 2 to 6 phr. 10. A tire according to any preceding claim wherein the tackifying resin has a number average molecular weight (Mn) greater than 1000 g / mol, preferably greater than 1200 g / mol. 11. A tire according to any one of the preceding claims wherein 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 wherein the total plasticizer content 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 wherein the plasticizing oil is selected from the group consisting of naphthenic oils, paraffinic oils, MES oils, TDAE oils, mineral oils, vegetable oils, plasticizers ethers, ester plasticizers, phosphate plasticizers, sulphonate plasticizers and mixtures of these compounds. Tire according to any one of the preceding claims, in which the plasticizing oil is a vegetable oil whose iodine number 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. A tire according to any one of the preceding claims wherein the level of plasticizing oil is in a range from 25 to 45 phr, more preferably from 27 to 40 phr. 16. A tire according to any one of the preceding claims wherein the plasticizing resin is selected from the group consisting of cyclopentadiene or dicyclopentadiene homopolymer or copolymer resins, terpene homopolymer or copolymer resins, terpene phenol copolymer resins, C5 homopolymer or copolymer resins, resins homopolymers or copolymers of C9 cut, resins of homopolymers and copolymers of alpha-methyl-styrene and mixtures of these resins. 17. A tire according to any one of the preceding claims wherein the level of plasticizing resin is in a range from 25 to 45 phr, more preferably from 27 to 40 phr. 18. A tire according to any preceding claim wherein the amounts of filler and plasticizer are such that the ratio of the amount of filler in phr to the amount of plasticizer in pce is in 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 wherein the tread comprises a composition as defined according to one of claims 1 to 18.