WO2009062735A1

WO2009062735A1 - Tyre rubber composition containing polynorbornene and a liquid plasticiser

Info

Publication number: WO2009062735A1
Application number: PCT/EP2008/009654
Authority: WO
Inventors: Didier Vasseur; Garance Lopitaux
Original assignee: Societe De Technologie Michelin; Michelin Recherche Et Technique S.A.
Priority date: 2007-11-16
Filing date: 2008-11-14
Publication date: 2009-05-22
Also published as: FR2923833A1; FR2923833B1

Abstract

The invention relates to a rubber composition containing at least: a styrene-butadiene (SBR) copolymer having a glass transition temperature (Tg) above - 40 °C; a polynorbornene; a reinforcing filler; and a liquid plasticiser having a glass transition temperature (Tg) below - 20 °C, selected from the group containing ethers, esters, phosphates, sulphonates and mixtures of said compounds. The invention also relates to the use of one such composition for the production of a tyre tread having an improved trade-off between wet surface grip and rolling resistance.

Description

PNEUMATIC RUBBER COMPOSITION BASED ON POLYNORBORNENE AND A LIQUID PLASTICIZER

The present invention relates to rubber compositions intended in particular for the manufacture of tires or semi-finished products for tires; it relates more particularly to the rubber compositions that can be used in the treads of these tires.

A tire tread must obey in a known manner to a large number of technical requirements, often antithetical, among which a low rolling resistance, a high wear resistance, as well as a high grip on dry and wet roads. . The combined improvement of the properties of adhesion and rolling resistance remains a constant concern of tire designers.

Unexpectedly, the Applicants discovered during their research a new rubber composition, based on a specific styrene-butadiene copolymer, a polynorbornene and a liquid plasticizer, which makes it possible to obtain tires having a improved wet grip and rolling resistance, without penalizing the behavior.

Thus a first object of the invention relates to a rubber composition, said composition being based on at least:

a styrene-butadiene copolymer (SBR) called "high Tg", whose glass transition temperature (Tg) is greater than -40 ^° C .; a polynorbornene; a reinforcing filler;

a liquid plasticizer called "low Tg", whose Tg is less than -20 ° C., chosen from the group consisting of ethers, esters, phosphates, sulphonates and mixtures of these compounds.

The invention also relates to a method for preparing a rubber composition according to the invention, this method comprises the following steps:

- Incorporate an SBR elastomer of Tg greater than -40 ⁰ C, during a first step (called "non-productive"), at least one polynorbornene and a liquid plasticizer whose Tg is less than -20 ⁰ C selected in the group consisting of ethers, esters, phosphates, sulphonates and mixtures of these compounds, by mixing

P 10-2046 PCT thermomechanically all until reaching a maximum temperature between 1 10 ° C and 190 ° C; cool the assembly to a temperature below 100 ° C; then incorporate, during a second step (called "productive"), a crosslinking system; knead everything to a maximum temperature below HO ⁰ C.

The invention also relates to the use of this rubber composition for the manufacture of tires or semi-finished products for tires, in particular tire treads, that these are intended for the manufacture of new tires such as retreading used tires.

The invention also relates to tires or semi-finished products for tires comprising a rubber composition according to the invention.

The tires according to the invention are particularly intended for passenger vehicles such as two-wheeled vehicles (motorcycle, bicycle), industrial vehicles chosen from light trucks, "heavy goods vehicles" - ie, metro, buses, road transport vehicles (trucks tractors, trailers), off-the-road vehicles, agricultural or engineering machinery, aircraft, other transport or handling vehicles.

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

I - MEASUREMENTS AND TESTS USED

The rubber compositions are characterized, before and after firing, as indicated below.

I- 1. Shore A hardness

The Shore A hardness of the compositions after curing is assessed according to ASTM D 2240-86.

1-2. Traction tests

These tests make it possible to determine the elastic stress and the properties at break. Unless otherwise indicated, they are carried out in accordance with the French standard NF T 46-002

P10-2046 PCT of September 1988. The nominal secant moduli (or apparent stresses, in MPa) at 10% elongation (noted after an accommodation cycle at the expected extension rate for the measurement itself) are measured in second elongation (ie MlO), 100% elongation (denoted MlOO) and 300% elongation (denoted M300). All these tensile measurements are carried out under the normal conditions of temperature (23 ± 20 ^° C.) and hygrometry (50 ^° C.). ± 5% relative humidity), according to the French standard NF T 40-101 (December 1979).

1-3. Tire tests

A) Rolling resistance

The rolling resistance of tires is measured on a steering wheel according to ISO 87-67 (1992). A value greater than that of the control, arbitrarily set at 100, indicates an improved result, that is to say a rolling resistance lower than that of the control tire.

B) Braking on wet ground with an ABS system

The tires are mounted on a motor vehicle equipped with an ABS braking system and the distance necessary to go from 50 km / h to 10 km / h is measured during a sudden braking on wet ground (bituminous concrete). A value greater than that of the control, arbitrarily set at 100, indicates an improved result, i.e. a shorter braking distance.

C) Braking on wet ground with locked wheels

The grip of the tires is also evaluated by measuring the braking distances in the "two-wheel locked" braking mode. The braking distance is measured from a speed of 40 km / h to a speed of 0 km / h on wet ground. A value greater than that of the control, arbitrarily set at 100, indicates an improved result, i.e. a shorter braking distance.

D) Adhesion on wet ground

To assess wet grip performance, we analyze the behavior of tires mounted on a specific motor vehicle, traveling under conditions of limit speed, a highly virulent circuit and watered so as to keep the soil moist. The minimum time required to travel the entire circuit is measured; a value greater than that of the control, arbitrarily set at 100, indicates an improved result, that is to say a shorter travel time.

P 10-2046 PCT - AT -

II. CONDITIONS FOR CARRYING OUT THE INVENTION

The rubber composition according to the invention, usable especially for the manufacture of a tire or a tire tread, is based on at least:

a styrene-butadiene copolymer (SBR) called "high Tg", whose glass transition temperature (Tg) is greater than -40 ^° C .; a polynorbornene; a reinforcing filler; a liquid plasticizer called "low Tg" whose Tg is less than - 20 ⁰ C, selected from the group consisting of ethers, esters, phosphates, sulfonates and mixtures of these compounds.

By the term "composition-based" is meant a composition comprising the mixture and / or the reaction product of the various constituents used, some of these basic constituents being capable of or intended to react with one another, less in part, during the various phases of manufacture of the composition, in particular during its crosslinking or vulcanization.

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

II.1 - SBR elastomer with high Tg

The rubber composition according to the invention has the essential characteristic of comprising, as diene elastomer, a styrene-butadiene copolymer (SBR) whose glass transition temperature (Tg) is greater than -40 ° C., referred to herein as after "SBR high Tg" or "SBR high Tg", said temperature being measured (by DSC, according to ASTM D3418 - 1999) on elastomer in the dry state (ie, without extension oil).

Preferably, a high Tg SBR having a styrene content of between 5% and 50% by weight and more particularly between 20% and 40%, a 1,2-butadiene content of the butadiene part of between 4% and 65% is used. %, a trans-1,4 bond content of between 20% and 80%. Those skilled in the art know how to modify the microstructure of an SBR elastomer to adjust its Tg.

P 10-2046 PCT According to one particular embodiment of the invention, the rubber composition comprises between 40 and 95 phr, in particular between 60 and 90 phr, of SBR with a high Tg.

According to another preferred embodiment, the high SBR Tg has a Tg preferably between -40 ⁰ C and 0 ⁰ C, especially between -30 ° C and 0 ° C, and more preferably between -30 ⁰ C and - 5 ° C, for example between

- 25 ⁰ C and - 5 ° C.

At SBR high Tg above, may be or may be associated with one or more other diene elastomer (s). By elastomer or "diene" rubber, it is to be understood in a known manner (one or more elastomers) are understood to come from at least a part (ie a homopolymer or a copolymer) of monomers dienes (monomers bearing two carbon-carbon double bonds, conjugated or not).

The optional additional diene elastomer is preferably selected from the group consisting of polybutadienes (BR), synthetic polyisoprenes (IR), natural rubber (NR), butadiene copolymers, isoprene copolymers (other than IR) and mixtures of these elastomers. Such copolymers are more preferably selected from the group consisting of isoprene-butadiene copolymers (BIR), isoprene-styrene copolymers (SIR), isoprene-butadiene-styrene copolymers (SBIR).

Suitable polybutadienes and in particular those having a content (mol%) in units -1.2 of between 4% and 80% or those having a content (mol%) of cis-1,4 greater than 80%, polyisoprenes, copolymers of butadiene-isoprene and in particular those having an isoprene content of between 5% and 90% by weight and a Tg of -40 ^° C. to -80 ^° C., the isoprene-styrene copolymers and in particular those having a styrene content between 5% and 50% by weight and a Tg between -25 ° C and -50 ^° C. In the case of butadiene-styrene-isoprene copolymers are especially suitable those having a styrene content of between 5% and 50% by weight and more particularly between 10% and 40%, an isoprene content of between 15% and 60% by weight and more particularly between 20% and 50%, a butadiene content of between 5% and 50% by weight and more particularly between 20% and 40%, a content (mol%) in units -1,2 of the p butadiene part between 4% and 85%, a content (mol%) in trans-1,4 units of the butadiene part of between 6% and 80%, a content (mol%) in units -1,2 plus -3 , 4 of the isoprenic part of between 5% and 70% and a content (mol%) in trans-1,4 units of the isoprene part of between 10% and 50%, and more generally any butadiene-styrene-isoprene copolymer having a Tg between -20 ^° C. and -70 ^° C. The previously described high-Tg SBR could be optionally added to another copolymer of

P 10-2046 PCT butadiene-styrene having a Tg less than or equal to -40 ^° C., in particular in a range of -70 ° C. to -40 ^° C.

II.2 - Polynorbornene

A second essential characteristic of the composition according to the invention is to comprise as a second elastomer, a polynorbornene.

The polynorbornene elastomers are known, they have been described as well as their method of preparation for example in the patent application EP 1 006 134. They have also been described in rubber compositions for tire treads (see for example documents U.S. Patents 4,946,887 or US 2005/0080190).

It is recalled that the norbornene monomer (or bicyclo [2.2.1] hept-2-ene) is produced by Diels-Alder type addition of ethylene with a cycloolefin, is polymerized by a mechanism of ring opening to give a linear polymer with a repeating unit containing a 5 atom ring and a double bond.

Suitable cycloolefin monomers include substituted and unsubstituted norbornenes, dicyclopentadienes, dihydrodicyclopentadienes, dicylopentadiene trimers, tetracyclododecenes, hexacycloheptadecenes, ethylidenynorbornenes and vinylnorbornenes. Substituents on the cycloolefin monomers include hydrogen, alkyl, alkenyl, and aryl groups, with 1 to 20 carbon atoms and saturated and unsaturated cyclic groups with 3 to 12 carbon atoms that can be formed with a or more, preferably 2 rings of carbon atoms.

Polynorbornenes based for example on cyclopentadiene are commercially available, for example in an extended form with the oil (eg with 150 parts of naphthenic oil per 100 parts by weight of elastomer), in particular sold by the company Nippon Zéon under the denomination "Nosorex 150 NA" (Tg = + 35 ⁰ C).

The polynorbornene preferably has a glass transition temperature greater than 0 ^° C. It preferably has a high average molecular weight M w, typically ranging for example from several thousand to several million.

The polynorbornene is preferably used at a level of between 5 and 40 phr. Below 5 phr, the targeted effect may be insufficient while beyond 40 phr, there is a risk of excessive stiffening of the matrix. For these reasons, the level of polynorbornene is more preferably between 10 and 30 phr, in particular in a range of 10 to 20 phr,

P 10-2046 PCT in particular when the rubber composition of the invention is intended for a tread of a tourism type vehicle.

II.3 - Liquid plasticizer at low Tg

Another essential feature of the rubber composition of the invention is that it comprises a so-called "low Tg" liquid plasticizer whose Tg is less than -20 ° C., preferably less than -40 ° C., and which is chosen from the group consisting of ethers, esters, phosphates, sulfonates and mixtures of these compounds.

Preferably, said low Tg liquid plasticizer is selected from the group consisting of esters, phosphates and mixtures of these compounds.

Particularly preferred are compounds selected from the group consisting of phosphates, trimellitates, pyromellitates, phthalates, 1,2-cyclohexane dicarboxylates, adipates, azelates, sebacates, glycerol triesters and mixtures thereof. .

Among the above compounds, dibutyl phthalate, dioctyl phthlate, diisononyl phthalate, diisodecyl phthalate, diisotridecyl phthalate, diundecyl phthalate, dioctyl sebacate, dibutyl sebacate, dioctyl adipate, diisodecyl adipate, diisononyl adipate, di butoxy-ethoxy-ethyl) adipate, tricresyl phosphate, trixylyl phosphate, trioctyl phosphate, diphenyl cresyl phosphate, diphenyloctyl phosphate, trichloroethyl phosphate, butyl stearate, dioctyl azelate, dibutyl oleate, trioctyl mellilate, dibutylmethylene bisthioglycolate, di-2-ethylhexyl ester thiodiglycolate.

Preferred phosphates are those containing from 12 to 30 carbon atoms. Examples of these compounds are trioctyl phosphate (especially tri-2-ethylhexyl phosphate), 2-ethylhexyl diphenyl phosphate, tricresyl phosphate, dodecyldiphenyl phosphate, tri-butoxyethyl phosphate and cresyl diphenyl phosphate.

Such preferred phosphates are commercially available; by way of example, mention may be made of the trioctyl phosphate marketed in particular under the name "Disflamoll TOF" (Tg = -105 ° C.) by the company Lanxess.

According to another particular embodiment of the invention, as liquid plasticizer at low Tg, use is made, for example, of a tri- or pyromellitate-type ester having the formula

(I):

P 10-2046 PCT

in which :

the radicals R, which may be identical or different, represent any hydrocarbon radical (or chain) (e) having 1 to 30 carbon atoms (and which may comprise a heteroatom chosen in particular from S, O and N);

R 'represents hydrogen (case of a trimellitate) or the group COOR (case of a pyromellitate).

Preferably, the radicals R represent a linear, branched or cyclic alkyl group containing from 1 to 20, even more preferably from 1 to 15 carbon atoms. By way of examples of such preferred R radicals comprising from 15 carbon atoms, there may be mentioned, for example, methyl, ethyl, butoxyethyl, butoxyethoxyethyl, propyl, propenyl, butyl, isobutyl, dibutyl, diisobutyl, benzylbutyl, heptyl and hexyl radicals. , ethylhexyl, octyl, isooctyl, benzyloctyl, dioctyl, diisooctyl, nonyl, isononyl, ethylnonyl, isodecyl, diisodecyl, tridecyl, octyldecyl.

A trimellitate of formula (II) is more particularly used:

in which the radicals R, identical or different, represent a hydrocarbon radical having 1 to 15 carbon atoms.

Such preferred trimellitates are commercially available. Examples of these trimellitates of formula (II) include the plasticizers of the "Palatinol" series, for example "TOTM" (R = C ₈ H _n ), "TNTM" (R = C ₉ H ₉ ) or "79TM" 1- (tri-ethyl-nonyl) from BASF. TOTM (trioctyl trimellitate or tri-2-ethylhexyl-1-trimetate) is especially used.

According to another particular embodiment of the invention, a low-level liquid plasticizer may be used, for example, a phthalate diester corresponding to formula (III):

P 10-2046 PCT

in which the radicals R, which may be identical or different, represent any hydrocarbon radical (or chain) (e) having from 1 to 30 carbon atoms (and which may comprise a heteroatom chosen in particular from S, O and N).

Preferably, the radicals R of formula (III) represent a linear, branched or cyclic alkyl group containing from 1 to 20, even more preferably from 1 to 15 carbon atoms. Examples of such preferred radicals R are dimethyl, diethyl, butoxyethoxyethyl, dibutyl, di-isobutyl, benzylbutyl, di-isoheptyl, dicyclohexyl, ethylhexyl or diethylhexyl, dibenzyl phthalates, dioctyl, di-isooctyl, butyloctyl, benzyloctyl, di-isononyl, ethylnonyl, di-isodecyl, octyldecyl, di-isotridecyl, di-undecyl, nonyl and undecyl, dodecyl and undecyl.

A phthalate diester is preferably used, the radicals R, which are identical or different, contain from 8 to 11 carbon atoms, in particular 9 or 10 carbon atoms, in particular those chosen from the group consisting of diisononyl phthalate or DINP "(R = C ₉ H ₉ ), di-isodecyl phthalate or" DIDP "(R = C ₁₀ H ₂ O) and mixtures of these compounds, such preferential phthalate diesters are commercially available. mention may be made of phthalates of the Palatinol series from BASF (for example "Palatinol DINP", "Palatinol DIDP").

According to another particular embodiment of the invention, as a low-Tg liquid plasticizer, it is possible to use, for example, a 1,2-cyclohexane dicarboxylate diester having the formula (IV):

P10-2046 PCT in which the radicals R, which may be identical or different, represent a hydrocarbon radical (or chain) chosen from the group consisting of alkyls, linear, branched or cyclic, containing from 1 to 30 carbon atoms, and aryls, aralkyls or alkaryls containing from 6 to 30 carbon atoms (this hydrocarbon radical may comprise a heteroatom chosen especially from S, O and N).

More preferably, in the formula (IV) above, the radicals R represent a linear, branched or cyclic alkyl group containing from 1 to 20, in particular from 1 to 15 carbon atoms. By way of examples of such preferred R radicals containing from 1 to 15 carbon atoms, which are identical or different in formula (I) above, mention may be made, for example, of methyl, ethyl, butoxyethyl, ethoxyethyl, propyl and propenyl radicals. , butyl, isobutyl, heptyl, isoheptyl, hexyl, cyclohexyl, ethylhexyl, benzyl, octyl, isooctyl, nonyl, isononyl, isodecyl, tridecyl, dodecyl, isotridecyl, undecyl.

A diester is preferably used whose radicals R, which are identical or different, contain from 8 to 11 carbon atoms, in particular 9 or 10 carbon atoms, particularly 1,2-cyclohexane dicarboxylate diisononyl, of formula (V):

Such a compound is known and commercially available, sold by BASF under the name "Hexamoll DINCH".

According to a particularly preferred embodiment of the invention, a low-carbon liquid plasticizer used a carboxylic acid diester of formula (VI):

R - O - OC - (CH ₂ ) - CO - O - R

in which n is in a range from 1 to 15 and the radicals R, which are identical or different, represent any hydrocarbon radical (or chain) (e) having from 1 to 30 carbon atoms (and which may comprise a chosen heteroatom, in particular among S, O and

NOT).

Preferably, n is in a range from 3 to 10 and the radicals R represent a linear, branched or cyclic alkyl group having from 4 to 15 carbon atoms. By way of examples of such preferential radicals R having from 4 to 15 carbon atoms, it is possible to

P10-2046 PCT for example, butoxyethyl, butoxyethoxyethyl, butyl, isobutyl, dibutyl, diisobutyl, benzylbutyl, heptyl, 2-ethylhexyl, benzyloctyl, dioctyl, diisooctyl, isononyl, isodecyl, diisodecyl, tridecyl and octyldecyl. A diester of adipic acid (or adipate, n = 4), azelaic acid (or azela- late, n = 7) or sebacic acid (or sebacate, n = 8) is particularly used, especially a diester of adipic acid or adipate (n = 4 in formula (VI) above).

Among the above adipates of formula (VI), are more preferably used those corresponding to formula (VII):

H _{2m +} C _m - O - OC - (CH ₂₎ ₄ - CO - OC _m H _{2m +}

in which m varies from 1 to 30, more preferably from 4 to 15, in particular from 7 to 13.

The preferred adipates of formula (VII) are di-isooctyl adipate (m = 8), diisononyl adipate (m = 9), di-isodecyl adipate (m = 10) and di-tridecyl adipate (m = 13). These adipates are commercially available. By way of examples, mention may be made of the plasticizers of the "Jayflex" series marketed by the company Exxon Mobil, in particular the adipates "Jayflex DIOA" (m = 8), "Jayflex DINA" (m = 9), "Jayflex DIDA "(m = 10), or" Jayflex DTDA "(m = 13). Other examples of these adipates of formula (VII) include the plasticizers of the "Adimoll" series from BAYER, "Plasthall" from CP HALL or "Diplast" from LONZA.

According to another preferred embodiment of the invention, it is possible to use as a low liquid plasticizer Tg a glycerol triester. By glycerol triester is also meant a mixture of triesters. This triester is preferably constituted mainly (for more than 50%, more preferably for more than 80% by weight) of an unsaturated fatty acid in

that is to say selected 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.

Those skilled in the art will be able to adjust the level of liquid plasticizer at low Tg according to the particular conditions of embodiment of the invention. It is preferably between 5 and 80 phr. Below the minimum indicated, the technical effect may be insufficient, while beyond 80 pce it is exposed to a decrease in tire adhesion

P 10-2046 PCT when the compositions of the invention are used in the treads of these tires. For these reasons, the diester content is more preferably between 5 and 40 phr, more preferably between 5 and 20 phr.

The liquid plasticizer at low Tg previously described has a Tg preferably between -120 ^° C. and -70 ^° C., more preferably between -110 ^° C. and -80 ^° C.

Of course, these compositions of the invention may also contain plasticizers other than liquid plasticizers with low Tg previously defined, such as for example non-aromatic or very weakly aromatic plasticizing agents, for example chosen from the group consisting of naphthenic oils. , paraffinic, MES oils, TDAE oils, hydrocarbon plasticizing resins and mixtures of such compounds.

According to a particularly preferred embodiment of the invention, the prior diester plasticizer is used as a second plasticizer, a hydrocarbon resin whose Tg is greater than 0 ° C, preferably greater than + 20 ^° C.

In a manner known to those skilled in the art, the term "resin" is reserved herein by definition to a compound which is solid on the one hand at room temperature (23 ^° C.) (as opposed to a plasticizer compound). liquid such as an oil), on the other hand compatible (that is to say miscible with the rate used, typically greater than 5 phr) with the rubber composition for which it is intended, so as to act as a real diluent.

Hydrocarbon resins are polymers well known to those skilled in the art, miscible by nature in diene (s) elastomer compositions (s) when they are further qualified as "plasticizers". They have been described, for example, in the book "Hydrocarbon Resins" by R. Mildenberg, M. Zander and G. Collin (New York, VCH, 1997, ISBN 3-527-28617-9), chapter 5 of which is devoted their applications, in particular pneumatic rubber (5.5 "Rubber Tires and Mechanical Goods"). They may be aliphatic, 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). They are preferably exclusively hydrocarbon-based, that is to say they contain only carbon and hydrogen atoms.

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

a Tg greater than 20 ^° C., more preferably greater than 30 ^° C.;

P 10-2046 PCT 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 3, more preferably less than 2

(recall: Ip = Mw / Mn with Mw weight average molecular weight).

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

The macrostructure (Mw, Mn and Ip) of the hydrocarbon resin is determined by steric exclusion chromatography (SEC): solvent tetrahydrofuran; temperature 35 ° C; concentration 1 g / 1; flow rate 1 ml / min; filtered solution on 0.45 μm porosity filter before injection; Moore calibration with polystyrene standards; set of 3 columns

"WATERS" in series ("STYRAGEL" HR4E, HR1 and HR0.5); differential refractometer detection ("WATERS 2410") and its associated operating software ("WATERS EMPOWER").

According to a particularly preferred embodiment, the plasticizing hydrocarbon resin is chosen from the group consisting of homopolymer or copolymer resins of cyclopentadiene (abbreviated as CPD) or dicyclopentadiene (abbreviated as DCPD), terpene homopolymer or copolymer resins, C5 homopolymer or copolymer resins, and mixtures of these resins.

Among the above copolymer resins are preferably used those selected from the group consisting of copolymer resins (D) CPD / vinylaromatic, copolymer resins (D) CPD / terpene, copolymer resins (D) CPD / cut C5, terpene / vinylaromatic copolymer resins, C5 / vinylaromatic cut 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. .

Suitable vinylaromatic monomers are, for example, styrene, phenol, alpha-methylstyrene, ortho-, meta-, para-methylstyrene, vinyl-toluene, para-tertiarybutylstyrene, methoxystyrenes, chlorostyrones, vinylmesitylene, divinylbenzene, vinylnaphthalene, any vinyl aromatic monomer from a C ₉ cut (or more generally from a C ₈ to Ci _0). Preferably, the vinylaromatic monomer is styrene or a vinylaromatic monomer resulting from a C ₉ cut (or more generally from a

P 10-2046 PCT C ₈ to C ₁₀ cut). Preferably, the vinylaromatic monomer is the minor monomer, expressed as a mole fraction, in the copolymer under consideration.

According to a more particularly preferred embodiment, the plasticizing hydrocarbon resin is chosen from the group consisting of homopolymer resins (D) CPD, copolymer resins (D) CPD / styrene, polylimonene resins, copolymer resins limonene / styrene, limonene / D (CPD) copolymer resins, C5 / styrene cut copolymer resins, C5 / C9 cut copolymer resins, and mixtures of these resins.

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 L 120" (Mn = 625 g / mol, Mw = 100 g / mol, Ip = 1.6, Tg = 72 ° C.) or by the company ARIZONA under the name "Sylvagum TR7125C" (Mn = 630 g / mol, Mw = 950 g / mol, Ip = 1.5, Tg = 70 ° C); such resins have been described in more detail in WO 2005/087859;

C ₅ / vinylaromatic copolymer resins, in particular C ₅ / styrene or C ₅ / C ₉ cuts: 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 the names "Hikorez Tl 095" and "Hikorez Tl 100", by Exxon under the names "Escorez 2101" and "ECR 373"; such resins have been described in more detail in WO 2006/061064;

Terpene / vinylaromatic copolymer resins, such as limonene / styrene copolymer or terpene / phenol copolymer: by the company DRT under the name "Dercolyte TS 105", by ARIZONA Chemical Company under the names "ZTl 15LT" and "ZT5100") or "Sylvares TP "; such resins have been described in more detail in WO 2007/017060.

The content of hydrocarbon resin is preferably between 5 and 60 phr. Below the minimum indicated, the technical effect may be insufficient, whereas beyond 60 pce the stickiness of the compositions in the green state, on the mixing tools, can in some cases become unacceptable. industrial point of view. For these reasons, the level of hydrocarbon resin is more preferably between 5 and 50 phr, more preferably between 10 and 40 phr.

P10-2046 PCT As for the overall rate of plasticizer system according to the invention, comprising in combination the low liquid plasticizer Tg and the hydrocarbon resin, it is preferably between 10 and 100 phr, more preferably between 20 and 80 phr (in particular between 20 and 80 phr). 50 phr).

II .4 - Reinforcing filler

Any type of reinforcing filler known for its ability to reinforce a rubber composition that can be used for manufacturing tires, for example an organic filler such as carbon black, a reinforcing inorganic filler such as silica, or a cutting of these two types of filler, including a cut of carbon black and silica.

Suitable carbon blacks are all carbon blacks, especially blacks of the HAF, ISAF, SAF type conventionally used in tires (so-called pneumatic grade blacks). Among these, mention will be made more particularly of reinforcing carbon blacks of the 100, 200 or 300 series (ASTM grades), such as, for example, Nl 15 blacks,

No. 134, N234, N326, N330, N339, N347, N375, or, depending on the intended applications, 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).

As examples of organic fillers other than carbon blacks, mention may be made of the organic functionalized polyvinylaromatic fillers as described in applications WO-A-2006/069792 and WO-A-2006/069793.

By "reinforcing inorganic filler" is meant in this application, by definition, any inorganic or mineral filler (regardless of its color and origin (natural or synthetic), also called "white" filler, "clear" filler or "non-blackfiller" as opposed to carbon black, capable of reinforcing on its own, without any other means than an intermediate coupling agent, a rubber composition intended for the manufacture of tires, in other words capable of replacing, in its reinforcing function, a conventional carbon black of pneumatic grade, such a charge is generally characterized, in known manner, by the presence of hydroxyl groups (-OH) on its surface.

The physical state in which the reinforcing inorganic filler is present is indifferent whether in the form of powder, microbeads, granules, beads or any other suitable densified form. Of course we also mean by reinforcing inorganic filler

P 10-2046 PCT mixtures of different reinforcing inorganic fillers, in particular highly dispersible siliceous and / or aluminous fillers as described below.

Suitable reinforcing inorganic fillers are mineral fillers of the siliceous type, in particular silica (SiO 2), or of the aluminous type, in particular alumina (Al 2 O 3). 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 area both less than 450 m 2 / g, preferably from 30 to 400 m 2 / boy Wut. As highly dispersible precipitated silicas (so-called "HDS"), there may be mentioned, for example, the silicas Ultrasil 7000 and Ultrasil 7005 from the company Degussa, the silicas Zeosil 1165MP, 1135MP and 1115MP from the company Rhodia, the silica Hi-SiI EZ1 50G from PPG, the Zeopol 8715, 8745 and 8755 silicas of the Huber Company, the high surface area silicas as described in the application WO 03/16837.

When the compositions of the invention are intended for tire treads with a low rolling resistance, the reinforcing inorganic filler used, in particular if it is silica, preferably has a BET surface area of between 45 and 400. m ² / g, more preferably between 60 and 300 m / g.

Preferably, the total reinforcing filler content (carbon black and / or reinforcing inorganic filler such as silica) is between 20 and 200 phr, more preferably between 30 and 150 phr, the optimum being in a known manner different according to particular applications targeted: the level of reinforcement expected on a bicycle tire, for example, is of course less than that required on a tire capable of running at high speed in a sustained manner, for example a motorcycle tire, a tire for a passenger vehicle or for commercial vehicles such as heavy goods vehicles.

According to a preferred embodiment of the invention, use is made of a reinforcing filler comprising between 30 and 150 phr, more preferably between 50 and 120 phr of inorganic filler, particularly of silica, and optionally carbon black; the carbon black, when present, is preferably used at a level of less than 20 phr, more preferably less than 10 phr (for example between 0.1 and 10 phr).

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

P 10-2046 PCT In particular, polysulfide silanes, called "symmetrical" or "asymmetrical" silanes 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, polysulphide silanes known as "symmetrical" silanes having the following general formula (VIII) are suitable, but not limited to, below:

(VIII) Z - A - S _x - A - Z, wherein:

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

- A is a divalent hydrocarbon radical (preferably alkylene groups Ci-Ci ₈ or arylene groups C ₂ -C _6, particularly alkylene Ci-Ci _0, in particular C 1 -C _4, particularly propylene );

Z is one of the following formulas:

R1 R1 R2

- Si- R1; - Si- R2; - Si- R2, R2 R2 R2

in which:

the radicals R ¹ , substituted or unsubstituted, which are identical to or different from each other, represent a Ci-Ci ₈ alkyl, C ₅ -C ₈ cycloalkyl or C ₆ -C ₁₈ aryl group (preferably C ₁ -C ₈ alkyl groups); -C ₆ , cyclohexyl or phenyl, especially C 1 -C ₄ alkyl groups, more particularly methyl and / or ethyl).

- the radicals R ^2, substituted or unsubstituted, identical or different, represent an alkoxy group or Ci-Ci ₈ cycloalkoxy, C ₅ -C _{8 I} (preferably a group selected from alkoxyls and C ₈ cycloalkoxyls C ₅ -C ₈ , more preferably still a group selected from C ₁ -C ₄ alkoxyls, in particular methoxyl and ethoxyl).

In the case of a mixture of polysulfurized alkoxysilanes corresponding to formula (VIII) 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. But the invention can also be advantageously implemented for example with disulfide alkoxysilanes (x = 2).

As examples of silane polysulfides, are more particularly the bis (mono, trisulfide or tetrasulfide) of bis (alkoxyl (Ci-C ₄₎ -alkyl (C | -C4) alkyl silyl (Ci-C ₄ )), such as polysulfides of bis (3-trimethoxysilylpropyl) or

P 10-2046 PCT bis (3-triethoxysilylpropyl). Among these compounds, bis (3-triethoxysilylpropyl) tetrasulfide, abbreviated to TESPT, of formula [(C ₂ H ₅ O) ₃ Si (CH ₂ ) ₃ S ₂ ] ₂ or bis-disulfide ( triethoxysilylpropyl), abbreviated TESPD, of formula [(C ₂ H ₅ O) ₃ Si (CH ₂ ) ₃ S] ₂ . Mention may also be made, by way of preferred examples, of polysulfides (in particular disulphides, trisulphides or tetrasulfides) of bis- (C 1 -C 4 monoalkoxyl) -dialkyl (C 1 -C 4) silylpropyl), more particularly bis-monoethoxydimethylsilylpropyl tetrasulfide, as described above. in the patent application WO 02/083782 (or US 2004/132880).

As coupling agent other than polysulfurized alkoxysilane, there may be mentioned in particular bifunctional POS (polyorganosiloxanes) or hydroxysilane polysulfides (R ² = OH in formula VIII above) as described in patent applications. WO 02/30939 (or US 6,774,255) and WO 02/31041 (or US 2004/051210), or alternatively 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 4 and 12 phr, more preferably between 3 and 8 phr.

Those skilled in the art will understand that, as the equivalent filler of the reinforcing inorganic filler described in this paragraph, it would be possible to use a reinforcing filler of another nature, in particular an organic filler, since this reinforcing filler would be covered with a filler. inorganic layer such as silica, or would comprise on its surface functional sites, especially hydroxyl, requiring the use of a coupling agent to establish the bond between the filler and the elastomer.

II-5. Various additives

The rubber compositions in accordance with the invention also comprise all or part of the usual additives usually used in elastomer compositions intended for the manufacture of tires, in particular treads, such as, for example, pigments, protective agents such as anti-ozone waxes, chemical antiozonants, antioxidants, anti-fatigue agents, reinforcing resins, acceptors (for example phenolic novolac resin) or methylene donors (for example HMT or H3M), a crosslinking system based on either sulfur, or sulfur and / or peroxide and / or bismaleimide donors, vulcanization accelerators, vulcanization activators.

These compositions may also contain, in addition to the coupling agents, coupling activators, inorganic charge-covering agents or, more generally, processing aids that can be used in a known manner, thanks to an improvement in the dispersion. of the load in the rubber matrix and to a

P10-2046 PCT lowering the viscosity of the compositions, to improve their ability to implement in the green state, these agents being, for example, hydrolysable silanes such as alkylalkoxysilanes, polyols, polyethers, primary, secondary or tertiary amines, hydroxylated or hydrolyzable polyorganosiloxanes.

II-6. 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 (so-called "non-productive" phase) at high temperature, up to a maximum of maximum temperature between 110 ° C and 190 ^° C, preferably between 130 ⁰ C and 18O ⁰ C, followed by a second phase of mechanical work (so-called "productive" phase) to a lower temperature, typically less than 110 ⁰ C, for example between 40 ⁰ C and 100 ⁰ C, finishing phase during which is incorporated the crosslinking system.

The process according to the invention for preparing a rubber composition comprises the following steps:

to incorporate in an SBR elastomer of Tg greater than -40 ^° C., during a first step (called "non-productive"), at least one polynorbornene and a liquid plasticizer whose Tg is less than -20 ^° C. chosen in the group consisting of ethers, esters, phosphates, sulphonates and mixtures of these compounds, by thermomechanically kneading the whole (for example in one or more times), until a maximum temperature of between ^{0 °} C ^{0 °} C and 19O ⁰ C; - Cool all at a temperature below 100 ⁰ C; then incorporate, during a second step (called "productive"), a crosslinking system; - mix everything up to a maximum temperature below 110 ⁰ C.

By way of example, the non-productive phase is carried out in a single thermomechanical step during which, in a suitable mixer such as a conventional internal mixer, all the necessary basic constituents (SBR, polynorbornene, liquid plasticizer, other diene elastomer if appropriate, reinforcing filler and coupling agent in the case of an inorganic filler), then in a second step, for example after one to two minutes of mixing, the other additives, optional agents load recovery or additional implementation, with the exception of the crosslinking system. The total mixing time in this non-productive phase is preferably between 1 and 15 minutes.

P10-2046 PCT After cooling the mixture thus obtained, it is then incorporated in an external mixer such as a roll mill, maintained at low temperature (for example between 40 ⁰ C and 100 ° C), the crosslinking system. The whole is then mixed (productive phase) for a few minutes, for example between 2 and 15 min.

The actual crosslinking system is preferably based on sulfur and a primary vulcanization accelerator, in particular a sulfenamide type accelerator. To this vulcanization system are added, incorporated during the first non-producing phase and / or during the production phase, various known secondary accelerators or vulcanization activators such as zinc oxide, stearic acid, guanidine derivatives (especially diphenylguanidine), etc. The sulfur content is preferably between 0.5 and 3.0 phr, that of the primary accelerator is preferably between 0.5 and 5.0 phr.

It is possible to use as accelerator (primary or secondary) any compound capable of acting as a vulcanization accelerator for diene elastomers in the presence of sulfur, especially thiazole type accelerators and their derivatives, thiuram type accelerators, zinc dithiocarbamates. 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-benzothiazylsulfenamide (abbreviated "TBBS"), N-tert-butyl-2-benzothiazylsulfenimide (abbreviated "TBSI"), zinc dibenzyldithiocarbamate (in abbreviated "ZBEC") and mixtures of these compounds. Preferably, a primary accelerator of the sulfenamide type is used.

The final composition thus obtained can then be calendered, for example in the form of a sheet, a plate especially for a characterization in the laboratory, or extruded, for example to form a rubber profile used for the manufacture of a semi-finished tire product, such as treads, webs or other webs, underlays, various rubber blocks, whether or not reinforced with textile or metal reinforcements, for forming a part of the tire structure.

In the process according to the invention, in accordance with the preceding indications given for rubber compositions, at least one characteristic, more preferably all of the following characteristics which is verified:

SBR at high Tg has a Tg of between -40 ^° C. and 0 ^° C. the SBR content at high Tg is between 40 and 95 phr; polynorbornene has a Tg greater than 0 ⁰ C; the amount of polynorbornene is between 5 and 40 phr;

P 10-2046 PCT the liquid plasticizer has a Tg lower than -40 ° C .; the amount of liquid plasticizer is between 5 and 80 phr, the hydrocarbon resin has a Tg greater than 0 ⁰ C; the amount of hydrocarbon resin is between 5 and 60 phr.

The invention relates to tires, tire treads and rubber compositions previously described both in the green (i.e., before firing) and the fired (i.e. after crosslinking or vulcanization).

III. EXAMPLES OF CARRYING OUT THE INVENTION

IH-I. Preparation of compositions

The following tests are carried out as follows: an internal mixer, filled to 70% and whose initial tank temperature is approximately 60 ^° C., is introduced successively into the reinforcing inorganic filler (silica), the agent coupling agent, the plasticizer, the diene elastomer and the various other ingredients with the exception of the vulcanization system. Thermomechanical work (non-productive phase) is then carried out in one step, which lasts a total of about 3 to 4 minutes, until a maximum temperature of "fall" of 165 ° C is reached.

The mixture thus obtained is recovered, cooled, and sulfur and a sulfenamide type accelerator are incorporated on a mixer (homo-finisher) at 30 ° C., mixing the whole (productive phase) for a suitable time (for example between 5 hours). and 12 min).

The compositions thus obtained are then calendered either in the form of plates (thickness of 2 to 3 mm) or thin sheets of rubber for the measurement of their physical or mechanical properties, or extruded in the form of treads of passenger tires.

IH-2. Tire tests

Test 1: Rubber compositions reinforced with carbon black

This first test demonstrates the improvement, in terms of wet grip and rolling resistance, provided by a tread according to the invention, compared to two control treads.

P 10-2046 PCT For this, three rubber compositions were prepared as indicated above, one according to the invention (noted below C-1.2) and two non-compliant (noted below C-

1.1 and C-1.3). These three compositions use carbon black as a reinforcing filler (see Table 1).

Control composition C-1.1 is a reference composition for those skilled in the art, conventionally used to manufacture treads for passenger car tires, reinforced with carbon black; it is based on a copolymer of styrene-butadiene (high Tg) and polybutadiene.

The composition of the invention C-1.2 additionally contains, relative to the composition C-1.1, a polynorbornene and a liquid plasticizer at low Tg.

The control composition C-1.3 differs only from the composition of the invention C-1.2 by the use of an SBR elastomer which is not a high Tg SBR (that is to say with a Tg is not more than - 40 ⁰ C); it also contains polynorbornene and liquid plasticizer at low Tg.

These three compositions were tested as tire treads for passenger vehicles, dimensions 195 / 65R15, on a RENAULT brand passenger vehicle model LAGUNA, as indicated in paragraph 1-3 above.

Their formulations (in phr or parts by weight per hundred parts of elastomer, thus including polynorbornene), their mechanical properties as well as the results of the tire rolling tests have been summarized in the attached Tables 1 and 2.

It is noted initially that, compared to the control composition C-1.1, the addition of polynorbornene and liquid plasticizer low Tg in the composition of the invention C-

1.2 does not modify the rigidity (Shore hardness) nor, essentially, the mechanical properties in extension.

It is only during the running of the tires that, unexpectedly, there is a very significant improvement in both the rolling resistance and the adhesion on wet ground for the composition of the invention, as attested very clearly. by the results in Table 2 (gains of 5%, 16% and 8% on the three criteria tested). It must of course be concluded that this improvement is achieved by the addition of polynorbornene and liquid plasticizer low Tg in the composition of the invention.

A comparison, in a second step, of the composition of the invention C-1.2 and the composition C-1.3 not according to the invention (as a reminder, not distinguishable from that of

P10-2046 PCT the invention that by the use of a SBR elastomer at lower Tg), just as clearly demonstrates that the improved property compromise provided by the invention is totally lost when the SBR at high Tg (composition C-1.2) is replaced by a lower Tg SBR (composition C-1.3): it is then noted that the properties measured during the rolling of the tires then substantially cover the initial values (base 100) observed on the reference control composition (C-1.1), even are even inferior to these in terms of adhesion.

In summary, the results of this first test demonstrate that the combined use of high Tg SBR, polynorbornene and low Tg liquid plasticizer in the rubber composition of the invention significantly improves the compromise. rolling resistance and wet grip of tire treads.

Test 2: Silica Reinforced Rubber Compositions

This second test confirms the improvement provided by the invention in the case where the composition of the invention comprises silica as main reinforcing filler. The compositions tested are shown in Table 3.

Measurements of the properties of the rubber compositions and the results of tire rolling tests performed with these compositions are listed in Table 4.

The addition of polynorbornene and low Tg liquid plasticizer in the composition of the invention C-2.2 does not modify the rigidity (Shore hardness) of the composition or its mechanical properties significantly, compared to the control composition C-2.1 .

On the other hand, the rolling of the tires once again reveals a significant improvement in the rolling resistance and the adhesion on wet ground of the composition of the invention C-2.2 compared to the control C-2.1, with in particular a gain of 12 % for the wet grip test described in paragraph I-3-D.

A comparison of the composition of the invention C-2.2 and the control composition C-2.3 (as a reminder, being distinguished from that of the invention only by the use of a SBR elastomer at lower Tg), demonstrates just as clearly as the improved property compromise provided by the invention is totally lost when the SBR at high Tg (composition C-2.2) is replaced by a SBR at lower Tg (composition C-2.3): it is then noted that the measured tire rolling properties then substantially cover the initial values (base 100) observed on the reference control composition (C-2.1), or even are lower than these with respect to adhesion.

P 10-2046 PCT In conclusion, the results of this second test confirm those of the first test, namely that the rubber composition of the invention makes it possible to significantly improve the compromise of rolling resistance and adhesion on wet ground of treads of tires, without changing the rigidity of the matrix (which is attested by the Shore hardness values), that is to say without penalizing the behavior.

P 10-2046 PCT Table 1

(I) SBR solution (rate expressed as dry SBR); 25% of styrene, 58% of 1-2 polybutadiene units and 2% of trans-polybutadiene 1-4 units (Tg = -21 ^° C.); (2) SBR solution (rate expressed as dry SBR); 25% styrene, 24% polybutadiene units

1-2 and 48% of polybutadiene 1-4 trans units (Tg = -45 ° C)

(3) BR with 4.3% of 1-2; 2.7% trans; 93% cis 1-4 (Tg = -106 ⁰ C);

(4) polynorbornene (dry state) "Norsorex 150NA" from the company Nippon Zéon (Tg = + 35 ° C.) (ie 37.5 phr of polynorbornene extended to the oil); (5) N234 carbon black (ASTM grade);

(6) total aromatic oil (including SBR and polynorbornene extension oil);

(7) trioctyl phosphate (tri-2-ethylhexyl phosphate) (Lanxess "Disflamoll TOF" (Tg = -105 ^° C.));

(8) stearin ("Pristerene" from the company Uniquema); (9) zinc oxide (industrial grade - Umicore company);

(10) N-1,3-dimethylbutyl-N-phenylparaphenylenediamine (Santoflex 6-PPD from Flexsys);

(I 1) N-cyclohexyl-2-benzothiazyl sulfenamide (Santocure CBS from Flexsys).

Table 2

P 10-2046 PCT Table 3

(I) SBR solution (rate expressed as dry SBR); 25% of styrene, 58% of 1-2 polybutadiene units and 22% of polybutadiene 1-4 trans units (Tg = -21 ^° C.); (2) SBR solution (rate expressed as dry SBR); 25% styrene, 24% polybutadiene units

1-2 and 48% of polybutadiene groups 1-4 trans (Tg = -45 ⁰ C);

(3) BR with 4.3% of 1-2; 2.7% trans; 93% cis 1-4 (Tg = -106 ⁰ C);

(6) "Zeosil 1165MP" silica from Rhodia, type "HDS";

(7) coupling agent TESPT ("Si69" from Degussa);

(8) total aromatic oil (including SBR and polynorbornene extension oil);

(9) trioctyl phosphate (tri-2-ethylhexyl phosphate) (Lanxess "Disflamoll TOF" (Tg = -105 ^° C.));

(10) diphenylguanidine (Perkacit DPG from Flexsys);

(I I) stearin ("Pristerene" from the company Uniquema);

(12) zinc oxide (industrial grade - Umicore company);

(13) N-1,3-dimethylbutyl-N-phenylparaphenylenediamine (Santoflex 6-PPD from Flexsys);

(14) N-cyclohexyl-2-benzothiazyl sulfenamide (Santocure CBS from Flexsys).

P 10-2046 PCT Table 4

P10-2046 PCT

Claims

1 - Rubber composition based on at least:

a so-called "low Tg" liquid plasticizer, whose Tg is less than -20 ^° C., chosen from the group consisting of ethers, esters, phosphates, sulphonates and mixtures of these compounds.

2 - rubber composition according to claim 1, wherein the high Tg SBR content is between 40 and 95 phr.

3 - rubber composition according to claim 2, wherein the high Tg SBR content is between 60 and 90 phr.

The rubber composition according to any one of claims 1 to 3, wherein the Tg of SBR is from -40 ° C to 0 ° C.

The rubber composition according to claim 4, wherein the Tg of SBR at high Tg is -30 ° C to 0 ° C.

6 - The rubber composition according to any one of claims 1 to 5, wherein the polynorbornene level is between 5 and 40 phr.

7 - rubber composition according to claim 6 wherein the polynorbornene content is between 10 and 30 phr.

8 - The rubber composition according to any one of claims 1 to 7, wherein the reinforcing filler comprises carbon black and / or silica.

9 - The composition of chuck according to any one of claims 1 to 8, wherein the amount of reinforcing filler is between 20 and 200 phr.

10 - The rubber composition according to claim 9, wherein the amount of reinforcing filler is between 30 and 150 phr.

P10-2046 PCT 11 - The rubber composition according to any one of claims 1 to 10, wherein the liquid plasticizer low Tg has a Tg less than - 40 ⁰ C.

12. A rubber composition according to any one of claims 1 to 11, wherein the low Tg liquid plasticizer is selected from the group consisting of esters, phosphates and mixtures thereof.

13 - rubber composition according to claim 12, wherein the liquid plasticizer low Tg is selected from the group consisting of phosphates, trimellitates, pyromellitates, phthalates, 1,2-cyclohexane dicarboxylates, adipates, azelates sebacates, triesters of glycerol and mixtures of these compounds.

14 - rubber composition according to any one of claims 1 to 13, wherein the level of liquid plasticizer low Tg is between 5 and 80 phr.

15. The rubber composition as claimed in claim 14, in which the level of liquid plasticizer at low Tg is between 5 and 40 phr.

16 - A rubber composition according to any one of claims 1 to 15, comprising a hydrocarbon resin whose Tg is greater than 0 ° C.

The rubber composition according to claim 16, wherein the hydrocarbon resin is selected from the group consisting of homopolymer resins or copolymer of cyclopentadiene (abbreviated as CPD) or dicyclopentadiene (abbreviated DCPD), homopolymer resins or terpene copolymer, homopolymer resins or C5 cutting copolymer, and mixtures of these resins.

18. The rubber composition as claimed in claim 16, in which the amount of hydrocarbon resin is between 5 and 60 phr.

19 - Process for preparing a rubber composition according to any one of claims 1 to 18, characterized in that it comprises the following steps:

- Incorporate into an SBR elastomer of Tg greater than -40 ⁰ C, during a first step (called "non-productive"), at least one polynorbornene and a liquid plasticizer whose Tg is less than -2O ⁰ C selected in the group consisting of ethers, esters, phosphates, sulphonates and mixtures of these compounds, thermomechanically kneading the whole until a maximum temperature between ^{0 °} C and 190 ^° C;

P 10-2046 PCT cool the assembly to a temperature below 100 ⁰ C; then incorporate, during a second step (called "productive"), a crosslinking system; knead everything to a maximum temperature below 1 10 ⁰ C.

Tire comprising a rubber composition according to any one of claims 1 to 18.

Tire tread comprising a rubber composition according to any one of claims 1 to 18.

22 - Use of the composition according to any one of claims 1 to 18 for the manufacture of tires or semi-finished products for tires.

P 10-2046 PCT