Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
  • B60C1/0016—Compositions of the tread
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
  • C08L9/06—Copolymers with styrene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
  • C08K5/0016—Plasticisers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L31/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an acyloxy radical of a saturated carboxylic acid, of carbonic acid or of a haloformic acid; Compositions of derivatives of such polymers
  • C08L31/02—Homopolymers or copolymers of esters of monocarboxylic acids
  • C08L31/04—Homopolymers or copolymers of vinyl acetate
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L57/00—Compositions of unspecified polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • C08L57/02—Copolymers of mineral oil hydrocarbons

Definitions

• the present invention relates to tire treads and rubber compositions based on diene elastomer and a resin, usable for the manufacture of such treads of tires.
• a tire tread must obey in known manner a large number of technical requirements, often antithetical, among which low rolling resistance, high wear resistance, and high adhesion on wet road.
• a first subject of the invention relates to a tire whose tread comprises a rubber composition comprising at least one diene elastomer, a polyvinyl ester resin whose glass transition temperature (Tg) is less than 0 ° C. C, and a reinforcing filler.
• the tires of the invention are particularly intended to equip tourism-type motor vehicles, SUVs ("Sport Utility Vehicles"), two wheels (in particular motorcycles), aircraft, such as industrial vehicles chosen from light trucks and “heavy vehicles”. that is, metro, bus, road transport equipment (trucks, tractors, trailers), off-the-road vehicles such as agricultural or civil engineering machinery, other transport or handling vehicles.
• SUVs Sport Utility Vehicles
• two wheels in particular motorcycles
• aircraft such as industrial vehicles chosen from light trucks and "heavy vehicles”. that is, metro, bus, road transport equipment (trucks, tractors, trailers), off-the-road vehicles such as agricultural or civil engineering machinery, other transport or handling vehicles.
• the rubber compositions of the tire treads are characterized before and after firing, as indicated below.
• the Mooney plasticity measurement is carried out according to the following principle: the raw composition (i.e., before firing) is molded in a cylindrical chamber heated to 100 ° C. After one minute of preheating, the rotor rotates within the test tube at 2 revolutions / minute and the useful torque is measured to maintain this movement after 4 minutes of rotation.
• Dynamic properties are measured on a viscoanalyzer (Metravib VA4000) according to ASTM D 5992-96.
• the response of a sample of vulcanized composition (cylindrical specimen 4 mm in thickness and 400 mm 2 in section) is recorded, subjected to a sinusoidal stress in alternating simple shear, at the frequency of 10 Hz, during a sweeping in temperature.
• the value of tan ( ⁇ ) observed at 0 ° C (tan ( ⁇ ) o ° c) is recorded.
• the essential characteristic of the tire according to the invention is that its tread comprises a rubber composition comprising at least one diene elastomer, a polyvinyl ester resin and a reinforcing filler, components which are described in detail below.
• 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).
• the tread of the tire according to the invention comprises a rubber composition whose first essential characteristic is to comprise at least one diene elastomer.
• elastomer or "rubber”, the two terms being considered synonymous
• diene monomers monomers bearing two carbon-carbon double bonds, conjugated or otherwise
• the diene elastomers can be classified into two categories: "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 rate of units or units of diene origin (conjugated dienes) which is greater than 15% (mol%); for example, diene elastomers such as butyl rubbers or copolymers of dienes and alpha-olefins of the EPDM type do not fall within the above definition and may in particular be described as "essentially saturated” diene elastomers ( low or very low diene origin, always less than 15%).
• the term “highly unsaturated” diene elastomer is particularly understood to mean a diene elastomer having a content of units of diene origin (conjugated dienes) which is greater than 50%.
• the term “diene elastomer” can be understood more particularly to be used in the compositions according to the invention:
• diene elastomer any type of diene elastomer
• the person skilled in the tire art will understand that the present invention is preferably implemented with essentially unsaturated diene elastomers, in particular of the type (a) or (b). ) above.
• conjugated dienes 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-di (C 1 -C 5) alkyl-1,3-butadienes, such as for example 2 3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-methyl-3-ethyl-1,3-butadiene, 2-methyl-3-isopropyl-1, 3-butadiene, aryl-1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene.
• alkyl-1,3-butadienes such as for example 2 3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-methyl-3-ethyl-1,3-butadiene, 2-methyl-3-isopropyl-1, 3-butadiene, aryl-1,3-butadiene, 1,3-pentadiene, 2,4-hexa
• Suitable vinylaromatic compounds are, for example, styrene, ortho-, meta-, para-methylstyrene, the "vinyl-toluene" commercial mixture, para-tert-butylstyrene, methoxystyrenes, chlorostyrenes, vinylmesitylene, divinylbenzene, viny lnaphthalene.
• the copolymers may contain between 99% and 20% by weight of diene units and between 1% and 80% by weight of vinylaromatic units.
• the elastomers may have any microstructure which is a function of the polymerization conditions used, in particular the presence or absence of a modifying and / or randomizing agent and the amounts of modifying and / or randomizing agent used.
• the elastomers can be for example block, statistical, sequenced, microsequenced, and 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.
• silanol or polysiloxane functional groups having a silanol end as described, for example, in FR 2,740,778, US 6,013,718 and WO 2008/141702
• alkoxysilane groups as described for example in FR 2,765,882 or US 5,977,238,
• carboxylic groups as described for example in WO 01/92402 or US 6,815,473, WO 2004/096865 or US 2006/0089445).
• polyether groups as described for example in EP 1 127 909, US 6,503,973, WO 2009/000750 and WO 2009/000752.
• functionalized elastomers mention may also be made of elastomers (such as SBR, BR, NR or IR) of the epoxidized type.
• elastomers such as SBR, BR, NR or IR
• 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 of greater than 80%, are suitable.
• polyisoprenes copolymers of butadiene-styrene and in particular those having a Tg (glass transition temperature (Tg, measured according to ASTM D3418) of between 0 ° C. and -70 ° C. and more particularly between -10 ° C. and -60 ° C.
• Tg glass transition temperature
• styrene content between 5% o and 60% by weight and more particularly between 20%> and 50%>, a content (%> molar) in -1,2 bonds of the butadiene part of between 4% and 75%, a content (mol%) of trans-1,4 bonds of between 10% and 80%, butadiene-isoprene copolymers and in particular those having an isoprene content of between 5% and 90% by weight and a Tg of -40 ° C to -80 ° C, isoprene-styrene copolymers and especially those having a styrene content of between 5% and 50% by weight and a Tg com between -5 ° C. and -60 ° C.
• butadiene-styrene-isoprene copolymers those having a styrene content of between 5% and 50% by weight and more particularly between 10% and 40% are particularly suitable.
• 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 of (mol%) in -1,2 units of the butadiene part of between 4% and 85% a content (mol%) in trans-1,4 units of the butadiene part of between 6% and 80%
• the diene elastomer of the composition is preferably chosen from the group of highly unsaturated diene elastomers consisting of polybutadienes (abbreviated "BR"), synthetic polyisoprenes (IR), natural rubber (NR), copolymers butadiene, isoprene copolymers and mixtures of these elastomers.
• BR polybutadienes
• IR synthetic polyisoprenes
• NR natural rubber
• Such copolymers are more preferably selected from the group consisting of butadiene-styrene copolymers (SBR), isoprene-butadiene copolymers (BIR), isoprene-styrene copolymers (SIR) and isoprene-copolymers.
• SBIR butadiene-styrene
• the composition comprises from 50 to 100 phr of an SBR elastomer, whether it be an emulsion-prepared SBR ("ESBR") or a SBR prepared in solution (“SSBR ").
• SBR emulsion-prepared SBR
• SSBR SBR prepared in solution
• the diene elastomer is a blend (mixture) SBR / BR.
• the diene elastomer is a SBR / NR (or SBR / IR), BR / NR (or BR / IR) or SBR / BR / NR (or SBR / BR / IR) blend. ).
• an SBR elastomer In the case of an SBR elastomer (ESBR or SSBR), an SBR having an average styrene content, for example between 20% and 35% by weight, or a high styrene content, for example 35 to 35% by weight, is used in particular. 45%, a vinyl ring content of the butadiene part of between 15% and 70%, a content (mol%) of trans-1,4 bonds of between 15% and 75% and a Tg of between -10 ° C. and - 55 ° C; such an SBR can be advantageously used in admixture with a BR preferably having more than 90% (mol%) of cis-1,4 bonds.
• the diene elastomer is an isoprene elastomer.
• isoprene elastomer is meant in known manner a homopolymer or copolymer of isoprene, in other words a diene elastomer selected from the group consisting of natural rubber (NR) which can be plasticized or peptized, the polyisoprenes of synthesis (IR), the various isoprene copolymers and the mixtures of these elastomers.
• NR natural rubber
• IR polyisoprenes of synthesis
• isoprene copolymers examples include isobutene-isoprene (butyl rubber - IIR), isoprene-styrene (SIR), isoprene-butadiene (BIR) or isoprene-butadiene-styrene copolymers. (SBIR).
• This isoprene elastomer is preferably natural rubber or synthetic cis-1,4 polyisoprene; among these polyisoprenes of synthesis, are preferably used polyisoprenes having a level (mol%) of cis-1,4 bonds greater than 90%, more preferably still greater than 98%.
• the rubber composition comprises a blend of one (or more) diene elastomers called "high Tg” having a Tg between -70 ° C and 0 ° C and d one (or more) diene elastomers known as "low Tg” between -1 10 ° C and -80 ° C, more preferably between -105 ° C and -90 ° C.
• the high Tg elastomer is preferably selected from the group consisting of S-SBR, E-SBR, natural rubber, synthetic polyisoprenes (having a molar ratio (% molar) of cis-1,4 preferably greater than 95%>), BIR, SIR, SBIR, and mixtures of these elastomers.
• the low Tg elastomer preferably comprises butadiene units at a level (mol%) of at least 70%; it consists preferably of a polybutadiene (BR) having a content (mol%) of cis-1,4 chains greater than 90%.
• the rubber composition comprises, for example, between 30 and 90 phr, in particular between 40 and 90 phr, of a high Tg elastomer in a blend with a low Tg elastomer.
• the diene elastomer of the composition according to the invention comprises a blend of a BR (as low elastomer Tg) having a rate (mol%) of cis chains -1, 4 greater than 90%, with one or more S-SBR or E-SBR (as elastomer (s) high Tg).
• compositions may contain a single diene elastomer or a mixture of several diene elastomers.
• the tread of the tire according to the invention comprises at least one polyvinyl ester resin whose Tg is less than 0 ° C.
• the Tg is measured in a known manner by DSC (Differential Scanning Calorimetry), according to the ASTM D3418 (1999) standard.
• the content of polyvinyl ester resin is preferably between 5 and 50 phr, and more preferably between 10 and 40 phr.
• the polyvinylester resin may be prepared according to any method of preparation known to those skilled in the art, that is to say by mass polymerization, in suspension, in solution in an organic solvent or emulsion.
• the molecular weight of the poly (vinyl ester) resin can be controlled by any method known to those skilled in the art, such as the addition of a chain length regulating agent, by the concentration of the reaction medium in monomer, by the radical initiator concentration and the polymerization temperature.
• the polyvinyl ester resin may in particular be prepared by esterification of a polyvinyl alcohol resin or by transesterification of a polyvinyl ester resin; these reactions are generally carried out in solution in a polar or apolar solvent, in the presence of an acidic or basic catalyst. It can also be prepared in a known manner by solution polymerization of the monomer (s) used (for example vinylhexanoate and vinylacetate in the examples which follow) in an organic solvent with a radical initiator.
• the vinyl ester monomer is derived from propionic, butyric, caproic, 2-ethylhexanoic, octanoic, lauric, pivalic, stearic or linoleic acids.
• the vinyl ester monomer can also be derived from the a branched acids of the carboxylic acid function and having 5 to 11 carbon atoms, such as the monomers "VeoVa9®”, “VeoValO®”, “VeoVal l®” derived from acids.
• Versatics Shell Chemicals).
• the acid may be linear or branched and may have one or more unsaturations.
• the poly (vinylester) resin whose Tg is less than 0 ° C. is a homopolymer chosen from the group consisting of poly (vinyl butyrate), poly (vinyl pentanoate), poly (vinyl hexanoate), poly (vinyl 2-ethylhexanoate), poly (vinyl decanoate), poly (vinyl laurate), poly (vinyl dodecanoate), poly (vinyl hexadecanoate), poly (vinyl octanoate), poly (vinyl versatate) and mixtures of these homopolymers.
• the poly (vinyl ester) resin whose Tg is less than 0 ° C. is a poly (vinylester) copolymer chosen from the group consisting of polyvinyl acetate-co-vinyl hexanoate), poly (vinyl acetate-co-vinyl 2-ethylhexanoate), poly (vinyl acetate-co-vinyl versatate), poly (vinyl acetate-co-vinyl laurate) and mixtures of these copolymers.
• the polyvinyl ester resin comprises at least one poly (vinyl hexanoate) or a copolymer derived from at least one vinyl hexanoate monomer such as, for example, a polyvinyl acetate. co-vinyl hexanoate).
• 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.
• Carbon blacks are suitable for all carbon blacks, especially so-called pneumatic grade blacks.
• the reinforcing carbon blacks of the 100, 200 or 300 series for example blacks NI 15, N134, N234, N326, N330, N339, N347 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).
• organic fillers other than carbon blacks mention may be made of functionalized polyvinyl organic fillers as described in applications WO-A-2006/069792, WO-A-2006/069793, WO-A-2008/003434 and WO-A-2008/003435.
• any inorganic or mineral filler (whatever its color and its natural or synthetic origin), also called “white” filler, “clear” filler or “black non-black filler” as opposed to carbon black, capable of reinforcing on its own, without any other means than an intermediate coupling agent, a rubber composition intended for the manufacture of tires, in other words capable of replacing, in its reinforcing function, a conventional carbon black of pneumatic grade; such a filler is generally characterized, in known manner, by the presence of hydroxyl groups (-OH) on its surface.
• -OH hydroxyl groups
• reinforcing inorganic filler also refers to mixtures of different reinforcing inorganic fillers, in particular highly dispersible siliceous and / or aluminous fillers as described below.
• Suitable reinforcing inorganic fillers are, in particular, 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 both less than 450 m 2 / g, preferably from 30 to 400 m 2 / g.
• highly dispersible precipitated silicas called "HDS"
• 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 2 / g.
• the total reinforcing filler content is between 50 and 200 phr, more preferably between 100 and 150 phr.
• a reinforcing filler comprising between 50 and 150 phr is used, more preferably between 50 and 120 phr of inorganic filler, particularly of silica, and optionally carbon black; the carbon black, when present, is used more preferably at a level of less than 20 phr, more preferably less than 10 phr (for example between 0.1 and 10 phr).
• an at least bifunctional coupling 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.
• 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).
• symmetrical polysulfide silanes having the following general formula (I):
• 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, especially C 1 -C 4 alkylenes, in particular propylene) ;
• R2 R2 in which:
• the radicals R 1 which may be substituted or unsubstituted, which are identical to or different from one another, represent a C 1 -C 18 alkyl, C 5 -C 18 cycloalkyl or C 6 -C 18 aryl group (preferably C 1 -C 6 alkyl groups), cyclohexyl or phenyl, especially C 1 -C 4 alkyl groups, more particularly methyl and / or ethyl).
• the radicals R 2 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 6 alkoxyls and C 5 -C 8 cycloalkoxyls); Cs, more preferably still a group selected from C 1 -C 4 alkoxyls, in particular methoxyl and ethoxyl).
• polysulphide silanes By way of examples of polysulphide silanes, mention may be made more particularly of bis (C 1 -C 4 ) alkoxy-C 1 -C 4 alkylsilyl-C 1 -C 4 alkyl (especially disulfide, trisulphide or tetrasulfide) polysulphides. )), such as polysulfides of bis (3-trimethoxysilylpropyl) or bis (3-triethoxysilylpropyl).
• TESPT bis (3-triethoxysilylpropyl) tetrasulfide
• TESPD bis (3-triethoxysilylpropyl) tetrasulfide
• TESPD bis (3-triethoxysilylpropyl) tetrasulfide
• TESPD bis (3-triethoxysilylpropyl) tetrasulfide
• polysulphides in particular disulfides, trisulfides or tetrasulfides
• bis-monoethoxydimethylsilylpropyl tetrasulfide as described in patent application WO 02/083782 (or US 2004/132880 ).
• POS polyorganosiloxanes
• 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.
• the content of coupling agent is preferably between 4 and 12 phr, more preferably between 4 and 8 phr.
• 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.
• the tread rubber compositions of the tires according to the invention may also comprise all or part of the usual additives normally used in elastomer compositions intended for the production of treads, for example pigments, such as antiozone waxes, chemical antiozonants, anti-oxidants, other plasticizers, anti-fatigue agents, reinforcing resins, acceptors (eg phenolic novolak resin) or methylene donors (eg example HMT or H3M), a crosslinking system based on either sulfur, or sulfur and / or peroxide donors and / or bismaleimides, vulcanization accelerators, vulcanization activators.
• pigments such as antiozone waxes, chemical antiozonants, anti-oxidants, other plasticizers, anti-fatigue agents, reinforcing resins, acceptors (eg phenolic novolak resin) or methylene donors (eg example HMT or H3M), a crosslinking system based on either sulfur, or sulfur and / or peroxide donors and
• 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 charge in the rubber matrix and a lowering of 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 hydrolysable polyorganosiloxanes.
• hydrolysable silanes such as alkylalkoxysilanes, polyols, polyethers, primary, secondary or tertiary amines, hydroxylated or hydrolysable polyorganosiloxanes.
• the composition of the tread of the tire according to the invention further comprises a plasticizer.
• this plasticizer is a solid hydrocarbon resin, a liquid plasticizer, or a mixture of both.
• the level of total plasticizer is preferably greater than 10 phr, more preferably between 10 and 100 phr, in particular between 20 and 80 phr, for example between 20 and 70 phr.
• the plasticizer is a liquid plasticizer at 20 ° C, said to "low Tg", that is to say which by definition has a Tg lower than -20 ° C, preferably below -40 ° C.
• any extender oil whether aromatic or non-aromatic, any liquid plasticizer known for its plasticizing properties vis-à-vis diene elastomers, is usable.
• these plasticizers or these oils are liquids (that is to say, as a reminder, substances having the capacity to eventually take on the shape of their container) , in contrast to, in particular, hydrocarbon plasticizing resins which are inherently solid at room temperature.
• liquid plasticizers selected from the group consisting of naphthenic oils (low or high viscosity, including hydrogenated or not), paraffinic oils, MES oils (Medium Extracted Solvates), Treated Distillate Aromatic Extracts (TDAE) oils, mineral oils, vegetable oils, ethers plasticizers, ester plasticizers, phosphate plasticizers, sulphonate plasticizers and mixtures of these compounds.
• phosphate plasticizers for example, mention may be made of those containing from 12 to 30 carbon atoms, for example trioctyl phosphate.
• ester plasticizers mention may be made in particular of compounds selected from the group consisting of trimellitates, pyromellitates, phthalates, 1,2-cyclohexane dicarboxylates, adipates, azelates, sebacates, glycerol and mixtures of these compounds.
• glycerol triesters preferably consisting mainly (for more than 50%, more preferably for more than 80% by weight) of a C 18 unsaturated fatty acid, that is 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, oils vegetable sunflower or rapeseed), the fatty acid used is more than 50% by weight, more preferably still more than 80% by weight of oleic acid.
• Such high oleic acid triesters are well known and have been described, for example, in application WO 02/088238, as plasticizers in tire treads.
• the level of liquid plasticizer is between 5 and 50 phr, more preferably between 10 and 40 phr, more preferably between 10 and 35 phr.
• this plasticizer is a thermoplastic hydrocarbon resin whose Tg is greater than 0 ° C, preferably greater than + 20 ° C. This resin is a solid at room temperature (23 ° C), as opposed to a liquid plasticizer such as an oil.
• the thermoplastic hydrocarbon plasticizing resin has at least one of the following characteristics: a Tg greater than 20 ° C, more preferably greater than 30 ° C;
• Mn a number-average molecular weight (Mn) of between 400 and 2000 g / mol, more preferentially between 500 and 1500 g / mol;
• thermoplastic hydrocarbon plasticizing 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 ⁇ porosity filter before injection; Moore calibration with polystyrene standards; set of 3 "WATERS” columns in series (“STYRAGEL” HR4E, HR1 and HR0.5); differential refractometer detection (“WATERS 2410") and its associated operating software (“WATERS EMPOWER”).
• SEC steric exclusion chromatography
• thermoplastic hydrocarbon resins may be aliphatic or aromatic or alternatively of the 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). Suitable aromatic monomers are, for example, styrene, alpha-methylstyrene, ortho-, meta-, para-methylstyrene, vinyl-toluene, para-tert-butylstyrene, methoxystyrenes, chlorostyrenes, vinylmesitylene and divinylbenzene.
• vinylnaphthalene any vinyl aromatic monomer from a C 9 fraction (or more generally a sectional Cs -C 10).
• the vinylaromatic monomer is styrene or a vinylaromatic monomer resulting from a C9 cut (or more generally from a Cs to C10 cut).
• the vinylaromatic monomer is the minor monomer, expressed as a mole fraction, in the copolymer under consideration.
• the plasticizing hydrocarbon resin is selected from the group consisting of homopolymer resins or copolymers of cyclopentadiene (abbreviated CPD) or dicyclopentadiene (abbreviated DCPD), terpene homopolymer or copolymer resins, terpene phenol homopolymer or copolymer resins, homopolymer or C5 cut copolymer resins, homopolymer or C9 cut copolymer resins, alpha-methyl-styrene homopolymer and copolymer resins and blends of these resins, used alone or in combination with a liquid plasticizer, for example a MES or TDAE oil.
• a liquid plasticizer for example a MES or TDAE oil.
• pene 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. .
• hydrocarbon plasticizing resins there may be mentioned resins of homo- or copolymers of alphapinene, betapinene, dipentene or polylimonene.
• the amount of plasticizing hydrocarbon resin is between 5 and 50 phr, preferably between 10 and 40 phr, more preferably between 10 and 35 phr.
• the rubber compositions can be manufactured in appropriate mixers, using two successive preparation phases well known to those skilled in the art: a first phase of work or thermomechanical mixing (so-called “non-productive” phase) at high temperature, up to at a maximum temperature of between 110 ° C. and 190 ° C., preferably between 130 ° C. and 180 ° C., followed by a second mechanical working phase (“productive" phase) to a lower temperature, typically below 110 ° C, for example between 40 ° C and 100 ° C, finishing phase during which is incorporated the crosslinking system.
• a first phase of work or thermomechanical mixing at high temperature, up to at a maximum temperature of between 110 ° C. and 190 ° C., preferably between 130 ° C. and 180 ° C.
• a second mechanical working phase (“productive” phase) to a lower temperature, typically below 110 ° C, for example between 40 ° C and 100 ° C, finishing phase during which is incorporated the crosslinking system.
• the process for preparing such compositions comprises, for example, the following steps: incorporating into a diene elastomer, during a first step (called “non-productive"), at least one polyvinyl ester resin and a reinforcing filler, thermomechanically kneading the whole (eg one or more times) until reaching a maximum temperature of between 110 ° C and 190 ° C;
• the non-productive phase is carried out in a single thermomechanical step in the course of which, in a suitable mixer such as a conventional internal mixer, all the necessary basic constituents (the diene elastomer, the poly (vinylester) resin, the reinforcing filler) and then, for a second time, for example after one to two minutes of mixing, the other additives, any optional charge-recovery or processing agents, with exception of the crosslinking system.
• the total mixing time in this non-productive phase is preferably between 1 and 15 minutes.
• the mixture thus obtained After cooling the mixture thus obtained, it is then incorporated in an external mixer such as a roll mill, maintained at low temperature (for example between 40 ° C and 100 ° C), the crosslinking system. The whole is then mixed (productive phase) for a few minutes, for example between 2 and 15 min.
• an external mixer such as a roll mill, maintained at low temperature (for example between 40 ° C and 100 ° C)
• 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.
• a primary vulcanization accelerator in particular a sulfenamide type accelerator.
• 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.
• accelerator 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.
• 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.
• MBTS 2-mercaptobenzothiazyl disulfide
• CBS N-cyclohexyl-2-benzothiazyl sulfenamide
• DCBS N-dicyclohex
• 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 tread.
• the invention relates to the tires previously described both in the green state (that is to say, before firing) and in the fired state (that is to say, after crosslinking or vulcanization).
• 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 (homoformer) at 30 ° C., mixing the whole (productive phase) for a suitable time (for example between 5 hours). and 12 min).
• compositions thus obtained are then calendered either in the form of plates (thickness of 2 to 3 mm) or thin sheets of rubber for the measurement of their physical or mechanical properties, or extruded in the form of a tread.
• the composition C1 is a control composition, based on SBR, which can be used in treads of "green tires” of passenger vehicles.
• the composition C.2 differs from the control composition C1, by the addition of 30 phr of polyvinyl ester resin whose glass transition temperature is below 0 ° C., a polyvinyl acetate-co-vinyl hexanoate). Both compositions are characterized by a very high rate of reinforcing filler.
• the compositions C 1 and C 2 further comprise a plasticizer mixture comprising a thermoplastic hydrocarbon resin (Tg C5 / C9 high resin) and a liquid plasticizer (sunflower oil).
• composition C.2 has a Mooney plasticity value slightly lower than that of the control composition Cl, which shows an improvement in the processability of the composition C. 2 in the raw state.
• composition C.2 has a level of rigidity (see in particular Shore A hardness and MA10) equivalent to that of the control composition Cl, and an elongation at break equivalent to that of the composition C l.
• composition C.2 has a value of tan ( ⁇ ) at 0 ° C. which is clearly greater than that of the control composition C 1, an indicator for a person skilled in the art of a wet road adhesion potential of tire treads which is improved.

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• 2010
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