Classifications

• • 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
• • 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
• • 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
• • 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
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/01—Hydrocarbons
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L21/00—Compositions of unspecified rubbers

Definitions

• 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 plasticizer systems used for the plasticization of such compositions.
• the tire rubber compositions comprise in a known manner plasticizing agents used for the preparation or synthesis of certain diene elastomers, to improve the implementation (or "processability") of said compositions in the green state, as well as some of their properties.
• use in the fired state such as, for example, in the case of treads of tires, their adhesion on wet ground or their resistance to abrasion and cuts.
• DAE oils for "Distillate Aromatic Extracts”
• MES for “Medium Extracted Solvates”
• TDAE Treated Distillate Aromatic Extracts
• “Chipping” ("chipping” or “scaling" is a known mechanism of damage which corresponds to superficial lamellar tearing - in the form of flakes - of the "gum” (or rubber composition) constituting the treads, under certain aggressive driving conditions.
• This problem is particularly encountered on tires for off-the-road vehicles or construction site or civil engineering, having to ride on different types of soil, for some stony and relatively aggressive; For example, it has been described, as well as some remedies, in EP-A-0 030 579 (or AU-A-6429780) and FR-A-2 080 661 (or GB-AI 343 487).
• the invention also relates to a method for preparing a rubber composition having improved abrasion and cut resistance, this composition being based on a diene elastomer, a reinforcing filler, a plasticizer system and of a crosslinking system, said method comprising the following steps:
• the invention also relates, in itself, to a plasticizer system useful for plasticizing a diene rubber composition, said system comprising in combination a MES or TDAE oil and a terpene / vinylaromatic copolymer resin, as well as the use of such a system for plasticizing a diene rubber composition.
• the invention also relates to the use of a composition according to the invention for the manufacture of a finished article or a semi-finished rubber product for any tire or tire / motor vehicle connection system such as internal safety support for tire, wheel, rubber spring, elastomeric joint, other suspension element and anti-vibration.
• the subject of the invention is particularly the use of a composition according to the invention for the manufacture of tires or semi-finished rubber products intended for these tires, these semi-finished products being preferably chosen from the group consisting of treads, crown reinforcement plies, sidewalls, carcass reinforcement plies, beads, guards, underlayments, rubber blocks and other internal rubbers, in particular decoupling erasers, intended to provide the connection or interface between the aforementioned zones of the tires.
• the invention more particularly relates to the use of a composition according to the invention for the manufacture of a tire tread having improved resistance to cuts and peeling.
• the invention also relates to finished articles and semi-finished products of rubber themselves, in particular tires and semi-finished products for tires, when they comprise an elastomeric composition according to the invention.
• the tires according to the invention are particularly intended for passenger vehicles such as two-wheeled vehicles (motorcycles, bicycles), industrial vehicles chosen from vans, "heavy trucks” - ie, metro, buses, road transport vehicles (trucks tractors, trailers), off-the-road vehicles -, agricultural or civil engineering machinery, airplanes, other transport or handling vehicles.
• composition according to the invention which can be used in particular for the manufacture of a tire or a tire tread, is based on at least one diene elastomer, a reinforcing filler, a crosslinking system and a system specific plasticizer.
• composition based on 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 each other, at least partly, during the various phases of manufacture of the composition, in particular during its crosslinking or vulcanization.
• elastomer or “diene” rubber it is to be understood in a known way (one or more elastomers), at least in part (ie, a homopolymer or a copolymer) of diene monomers (monomers bearing two carbon-to-carbon double bonds). , conjugated or not).
• 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 level of units or units of diene origin (conjugated dienes) which is greater than 15% (mol%);
• 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%.
• iene 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.
• 1,3-butadiene, 2-methyl-1,3-butadiene and 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.
• Suitable vinylaromatic compounds are, for example, styrene, ortho-, meta-, para-methylstyrene, the "vinyl-toluene" commercial mixture, para-tert-butylstyrene, methoxystyrenes, chlorostyrenes, vinylmesitylene, divinylbenzene, vinylnaphthalene.
• 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, sequence, microsequential, and be prepared in dispersion or in solution; they can be coupled and / or star or functionalized with a coupling agent and / or starring or functionalization.
• Suitable polybutadienes and in particular those having a content in units -1.2 of between 4% and 80% or those having a content of cis-1,4 greater than 80%, polyisoprenes, butadiene-styrene copolymers and in especially those 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%, a content of trans-1,4 of between 20% and 80%, butadiene-isoprene copolymers and especially those having an isoprene content of between 5% and 90% by weight and a glass transition temperature (Tg, measured according to ASTM D3418) from -40 ° C to -80 ° C, the isoprene-styrene copolymers and especially those having a styrene content of between 5% and 50% by weight and a Tg between -25 ° C and -50 ° C
• butadiene-styrene-isoprene copolymers are especially suitable those having a styrene content of between 5% and 50% by weight and more particularly of between 10% and 40%, an isoprene content of between 15% and 60%.
• the diene elastomer of the composition according to the invention is preferably selected from the group of highly unsaturated diene elastomers consisting of polybutadienes (abbreviated as "BR"), polyisoprenes (IR) and natural rubber (NR). , butadiene copolymers, isoprene copolymers and mixtures of these elastomers.
• BR polybutadienes
• IR polyisoprenes
• NR natural rubber
• butadiene copolymers isoprene copolymers and mixtures of these elastomers.
• 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.
• SBR butadiene-styrene
• the diene elastomer is predominantly (that is to say for more than 50 phr) an SBR, whether it is a SBR prepared in emulsion ("E-SBR") or a SBR prepared in solution (“S-SBR”), or a blend (mixture) SBR / BR, SBR / NR (or SBR / IR), or BR / NR (or BR / IR).
• E-SBR SBR prepared in emulsion
• S-SBR SBR prepared in solution
• an SBR elastomer use is made in particular of an SBR having a styrene content of between 20% and 30% by weight, a vinyl bond content of the butadiene part of between 15% and 65%, a bond content of trans-1,4 between 15% and 75% and a Tg of between -20 ° C and -55 ° C; such an SBR can be advantageously used in admixture with a BR preferably having more than 90% cis-1,4 bonds.
• the diene elastomer is predominantly (for more than 50 phr) an isoprene elastomer.
• the compositions of the invention are intended to constitute, in tires, the rubber matrices of certain treads (for example for industrial vehicles), crown reinforcing plies (for example work webs, protective webs or hoop webs), carcass reinforcement plies, flanks, beads, protectors, underlayments, rubber blocks and other internal gums providing the interface between aforementioned areas of the tires.
• isoprene elastomer in known manner a homopolymer or copolymer of isoprene, in other words a diene elastomer chosen from the group consisting of natural rubber (NR), synthetic polyisoprenes (IR), different isoprene copolymers and mixtures of these elastomers.
• NR natural rubber
• IR synthetic polyisoprenes
• isobutene-isoprene copolymers butyl rubber-HR
• isoprene-styrene copolymers SIR
• isoprene-butadiene copolymers BIR
• isoprene-butadiene-styrene copolymers SBIR
• This isoprene elastomer is preferably natural rubber or synthetic cis-1,4 polyisoprene; of these synthetic polyisoprenes, polyisoprenes having a content (mol%) of cis-1,4 bonds greater than 90%, more preferably still greater than 98%, are preferably used.
• the composition according to the invention may contain less than an essentially saturated diene elastomer, in particular at least one EPDM copolymer or a butyl rubber (optionally chlorinated or brominated), that these copolymers are used alone or in admixture with highly unsaturated diene elastomers as mentioned above, in particular NR or IR, BR or SBR.
• the rubber composition comprises a blend of one (or more) diene elastomers called "high Tg” having a Tg between -65 ° C and -10 0 C and of a (one or more) diene elastomer called "at low Tg” between -HO 0 C and -80 0 C, more preferably between -105 0 C and -80 0 C.
• the high Tg elastomer is chosen from preferably in the group consisting of S-SBR, E-SBR, natural rubber, synthetic polyisoprenes (having a level of cis-1,4 chains preferably greater than 95%), BIRs, SIRs, SBIR, and mixtures of these elastomers.
• the low Tg elastomer preferably comprises butadiene units at a content of at least 70%; it consists preferably of a polybutadiene (BR) having a degree of cis-1,4 chains higher than 90%.
• the rubber composition comprises, for example, from 40 to 100 phr, in particular from 50 to 100 phr, of a high Tg elastomer in a blend with 0 to 60 phr, in particular 0 to 50 phr of a low Tg elastomer, for example 100 phr of one or more copolymers of styrene and butadiene prepared in solution.
• the diene elastomer of the composition according to the invention comprises a blend of a BR (as low elastomer Tg) having a rate of cis-1,4 linkages. greater than 90%, with S-SBR or E-SBR (as high elastomer Tg).
• compositions of the invention may contain a single diene elastomer or a mixture of several diene elastomers, wherein the diene elastomer (s) may be used in combination with any type of synthetic elastomer other than diene, or even with polymers other than elastomers, for example thermoplastic polymers.
• reinforcing filler known for its capacity to reinforce a rubber composition that can be used for manufacturing tires, for example an organic filler such as carbon black, or a reinforcing inorganic filler such as silica to which is associated with a coupling agent.
• Carbon blacks are suitable for all carbon blacks, in particular blacks of the HAF, ISAF, SAF type conventionally used in tires (so-called pneumatic grade blacks).
• the reinforcing carbon blacks of the 100, 200 or 300 series for example blacks Nl 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).
• any inorganic or mineral filler (regardless of its color and origin (natural or synthetic), also called “white” filler, “clear” filler or “non-black load”, 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 particular 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.
• -OH hydroxyl groups
• 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.
• the term "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, especially any precipitated or fumed silica having a BET surface and a CTAB specific surface both less than 450 m 2 / g, preferably 30 to
• HD highly dispersible precipitated silicas
• Ultrasil 7000 and Ultrasil 7005 silicas from Degussa
• Hi-SiI silica EZ150G from PPG
• Zeopol 8715, 8745 and 8755 silicas from Huber high surface area silicas as described in application WO 03/16837 .
• reinforcing aluminas examples include the "Baikalox”"A125” or “CR125” aluminums from the Baikowski company, "APA-100RDX” from Condea, "Aluminoxid C” from Degussa or “AKP-GOl 5" from Sumitomo Chemicals.
• inorganic filler By way of other examples of inorganic filler that may be used, mention may be made of aluminum (oxide) hydroxides, titanium oxides or reinforcing silicon carbides (see, for example, application WO 02/053634 or US 2004 / 030,017).
• 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 content of total reinforcing filler is between 20 and 200 phr, more preferably between 30 and 150 phr, the optimum being in a known manner different according to the specific applications referred to.
• the level of reinforcement expected on a bicycle tire is of course lower 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 a commercial vehicle such as Heavyweight.
• 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).
• n is an integer of 2 to 8 (preferably 2 to 5);
• - A is a divalent hydrocarbon radical (preferably C 1 -C 18 alkylene or arylene groups groups C 6 -C 2, especially alkylenes CpCio, including Ci-C 4, especially propylene);
• radicals R 1 substituted or unsubstituted, identical or different, represent an alkyl group Ci-8 cycloalkyl, C 5 -C] 8 aryl or C 6 -C 8 (preferably alkyl C 1 -C 6 , cyclohexyl or phenyl, especially C 1 -C 4 alkyl groups, more particularly methyl and / or ethyl).
• radicals R 2 substituted or unsubstituted, identical or different, represent an alkoxy group or Ci-Ci 8 cycloalkoxy, C 5 -C 8 (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).
• n is a fractional number preferably between 2 and 5, more preferably close to 4.
• silane polysulfides are more particularly the bis (mono, trisulfide or tetrasulfide) of bis (alkoxyl (Ci-C4) alkyl (Ci -C 4) SiIyI- alkyl (Ci-C 4) ), such as polysulfides of bis (3-trimethoxysilylpropyl) or bis (3-triethoxysilylpropyl).
• TESPT bis (3-triethoxysilylpropyl) tetrasulfide
• TESPD bis (3-triethoxysilylpropyl) tetrasulfide
• TESPD bis-disulfide ( triethoxysilylpropyl)
• polysulfides in particular disulfides, trisulphides or tetrasulfides
• bis- (monoalkoxyl (Ci-C 4 ) -dialkyl (Ci-C 4 ) silylpropyl) more particularly bis-monoethoxydimethylsilylpropyl tetrasulfide.
• the content of coupling agent is preferably between 4 and 12 phr, more preferably between 3 and 8 phr.
• the coupling agent could be grafted beforehand on the diene elastomer or on the reinforcing inorganic filler. However, it is preferred, especially for reasons of better implementation of the compositions in the green state, to use the coupling agent is grafted onto the reinforcing inorganic filler, or in the free state (i.e., ungrafted).
• MES and TDAE oils are well known to those skilled in the art, see for example the recent publication KGK (Kautschuk für Kunstoffe) 52. Jahrgang, Nr. 12/99, pp. 799-805, entitled "Safe Process Oils for Tires with Low Environmental Impact”.
• Patent applications describing the use of such oils in substitution of conventional aromatic oils are, for example, EP-A1 179 560 (or US2002 / 0045697) or EP-A1 270 657.
• MES oils are well known to those skilled in the art, see for example the recent publication KGK (Kautschuk Gummi Kunstoffe) 52. Gonzgang, Nr. 12/99, pp. 799-805, entitled "Safe Process Oils for Tires with Low Environmental Impact”.
• Patent applications describing the use of such oils in substitution of conventional aromatic oils are, for example, EP-A1 179 560 (or US2002 / 0045697) or EP-A1 270 657.
• MES oils are well known to those skilled in the art, see for example
• resins are well known; they have been mainly used until now for their application as tackifiers in the food industry, or as plasticizers or processing aids in rubber tire compositions.
• Suitable vinylaromatic monomers are, for example, styrene, ortho-, meta-, para-methylstyrene, vinyl-toluene, para-tert-butylstyrene, methoxystyrenes, chlorostyrenes, vinylmesitylene, divinylbenzene, vinylnaphthalene.
• the vinyl aromatic compound is styrene.
• pene here combines in a known manner the alpha-pinene, beta-pinene and limonene monomers.
• a limonene monomer is used which is 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. .
• a monomer mixture consisting of 196 g of styrene and 204 g of limonene (or 4-isopropenyl-1-methyl-1-cyclohexene, Fluka product, purity> 99%) is added to the suspension dropwise for 5 minutes. .
• the temperature of the reaction medium increases to 58 ° C. After polymerization for 15 minutes, the reaction is quenched with 250 ml of deionized water.
• the content of terpene / vinylaromatic copolymer resin must be between 5 and 35 phr. Below the minimum indicated, the technical effect targeted is insufficient, whereas beyond 35 phr, the stickiness of the compositions in the green state, on the mixing tools, becomes unacceptable from the industrial point of view. For this reason, this level of resin is preferably between 5 and 25 phr, more preferably between 5 and 20 phr.
• That of the MES or TDAE oil is preferably between 10 and 30 phr, more preferably between 10 and 25 phr, while the total plasticizer system rate of the invention comprising the MES oil and / or TDAE and the resin, is preferably between 15 and 45 phr, more preferably between 20 and 40 phr.
• the terpene / vinylaromatic copolymer resin, in particular terpene / styrene has at least one (more preferably all) of the following preferred characteristics:
• a Tg greater than 25 ° C (more preferably greater than 30 0 C); a number-average molecular mass (Mn) of between 400 and 2000 g / mol; a polymolecularity index (Ip) of less than 3 (booster: Ip Mw / Mn with Mw weight average molecular weight); a rate of units derived from terpene monomer (in particular limonene) and a level of units derived from vinylaromatic monomer (in particular styrene) which are each between 5% and 95% (more particularly each between 10% and 90%) ).
• this resin has at least one (more preferably all) of the following preferred characteristics:
• Tg of between 30 ° C. and 80 ° C. (more particularly between 35 ° C. and 60 ° C.); a molecular weight Mn of between 600 and 1500 g / mol; a polymolecularity index Ip of less than 2.5; a level of units derived from vinylaromatic monomer (in particular styrene) greater than 40% (more particularly between 40% and 90%).
• the glass transition temperature Tg is measured in a known manner by DSC (Differential Scanning Calorimetry), according to the ASTM D3418 (1999) standard.
• the macrostructure (Mw, Mn and Ip) of the terpene / vinylaromatic copolymer is determined by steric exclusion chromatography (SEC): solvent tetrahydrofuran; temperature
• the plasticizer system of the invention further comprises between 5 and 35 phr (more preferably between 10 and 30 phr) of an unsaturated (Ci 2 -C 22 ) fatty acid triester of glycerol, in particular a glycerol trioleate (derived from oleic acid and glycerol), present for example in the form of a vegetable oil sunflower or rapeseed.
• glycerol unsaturated fatty acid triester of glycerol
• a glycerol trioleate derived from oleic acid and glycerol
• Such a triester makes it possible to minimize, in said tread, on the one hand the exudation in compression rolling of the total plasticizer system and, on the other hand, the migration of said plasticizer towards mixtures adjacent to the tread.
• the fatty acid (or all of the fatty acids if several are present) comprises oleic acid in a mass fraction of at least 60%.
• the overall rate of plasticizer system in the rubber composition of the The invention is preferably between 20 and 70 phr, more preferably between 30 and 60 phr.
• the plasticizer system of the invention could also comprise other non-aromatic or very weakly aromatic plasticizing agents, for example naphthenic, paraffinic, other hydrocarbon plasticizing resins having a high Tg preferably greater than 25 ° C, in combination with the terpene / vinylaromatic copolymer resin and the MES or TDAE oil previously described.
• non-aromatic or very weakly aromatic plasticizing agents for example naphthenic, paraffinic, other hydrocarbon plasticizing resins having a high Tg preferably greater than 25 ° C, in combination with the terpene / vinylaromatic copolymer resin and the MES or TDAE oil previously described.
• 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) as described, for example, in the US Pat. WO 02/10269 (or US 2003/212185), a crosslinking system based on either sulfur, or sulfur and / or peroxide donors and / or bismaleimides, vulcanization accelerators, vulcanization activators.
• 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, accept
• 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 use 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.
• 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 ° C and 180 ° 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.
• a first phase of work or thermomechanical mixing at high temperature, up to a maximum of maximum temperature between 110 ° C and 190 ° C, preferably between 130 ° C and 180 ° C
• a second phase of mechanical work so-called “productive” phase
• the method according to the invention for preparing a rubber composition having improved abrasion and cut resistance comprises the following steps:
• a MES or TDAE oil between 5 and 35 phr of a MES or TDAE oil; between 5 and 35 phr of a terpene / vinylaromatic copolymer resin (preferably terpene / styrene, in particular limonene / styrene).
• a terpene / vinylaromatic copolymer resin preferably terpene / styrene, in particular limonene / styrene.
• the non-productive phase is carried out in a single thermomechanical step during which all the necessary basic constituents (diene elastomer) are introduced into a suitable mixer such as a conventional internal mixer. , reinforcing filler and coupling agent if necessary, plasticizing system), then in a second step, for example after one to two minutes of kneading, the other additives, any additional coating or processing agents, with the exception of of the crosslinking system. After cooling the mixture thus obtained, it is then incorporated in an external mixer such as a roll mill, maintained at low temperature (for example between 40 0 C and 100 0 C), the crosslinking system. The whole is then mixed (productive phase) for a few minutes, for example between 2 and 15 min.
• a suitable mixer such as a conventional internal mixer.
• reinforcing filler and coupling agent if necessary, plasticizing system then in a second step, for example after one to two minutes of kneading, the other additives, any additional coating or processing agents, with the exception
• the crosslinking system is preferably a vulcanization system based on sulfur and an accelerator.
• Any compound capable of acting as an accelerator for vulcanization of diene elastomers in the presence of sulfur in particular those 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 to " DCBS "), N-tert-butyl-2-benzothiazylsulfenamide (abbreviated” TBBS “), N-tert-butyl-2-benzothiazylsulfenimide (abbreviated” TBSI ”) and mixtures of these compounds.
• a primary accelerator of the sulfenamide type is used.
• the sulfur content is for example between 0.5 and 3.0 phr, that of the primary accelerator between 0.5 and 5.0 pce.
• the final composition thus obtained can then be calendered, for example in the form of a sheet, a plate 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, reinforced or not with textile or metal reinforcements, intended to form a part of the tire structure, particularly its tread.
• a semi-finished tire product such as treads, webs or other webs, underlays, various rubber blocks, reinforced or not with textile or metal reinforcements, intended to form a part of the tire structure, particularly its tread.
• the vulcanization (or firing) may then be carried out in a known manner at a temperature generally of between 130 ° C. and 200 ° C., preferably under pressure, for a sufficient time which may vary, for example, between 5 and 90 min, depending in particular on the firing temperature, the vulcanization system adopted and the vulcanization kinetics of the composition under consideration.
• the invention relates to the rubber compositions described above both in the so-called “raw” state (i.e., before firing) and in the so-called “cooked” or vulcanized state (i.e. after vulcanization).
• composition according to the invention (hereinafter noted C-3) was compared with two control compositions (denoted C-I and C-2), the three compositions tested being identical, with the following differences:
• C-I control according to prior art with aromatic oil (37 phr);
• C-2 control with MES oil alone (31.5 phr);
• composition with plasticizer system according to the invention (combination of 12 phr of MES oil and 19.5 phr of limonene / styrene copolymer resin). These three compositions, with the exception of their plasticizer system, have a customary formulation for a tire tread rubber composition, namely essentially a mixture of diene elastomers (SSBR 70 pce / BR 30 pce), silica (78 phr), carbon black (4 phr) and a vulcanization system.
• Compositions CI and C-2 were formulated with iso-volume of plasticizing oil.
• about 2/3 (ie 19.5 phr) of MES oil were replaced by the limonene / styrene resin (19.5 phr) previously synthesized, compared with the control composition C-2.
• the three compositions were tested as treads of passenger tires with radial carcass, dimension 195/65 Rl 5 (speed index H), conventionally manufactured and in all respects identical except for the constitutive rubber composition of the tread.
• These tires are noted respectively PI, P-2 and P-3, they were mounted on a passenger vehicle (Citro ⁇ n model "C5" vehicle - front and rear pressure: 2.2 bars - tested tires mounted on the front of the vehicle - ambient temperature 25 ° C) to be subjected to an endurance test to assess the resistance to cuts and chipping of rubber compositions.
• the test was conducted at a moderate driving speed (less than 60 km / h), on two successive circuits:
• a first driving on a stony clay circuit (coarse grained stones), intended to weaken the tread, in the form of cuts and other superficial aggressions of the gum rolls constituting his sculpture;
• the state of the treads is evaluated on the one hand visually (photographs) by the attribution of a note (according to a gravity scale of 1 to 10), on the other hand by the measurement of weight loss. Resistance to peeling is finally appreciated by a relative overall score (base 100 on a reference product).

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