Classifications

• • 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
• • 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
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/02—Elements
  • C08K3/04—Carbon
• • 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
  • C08K5/04—Oxygen-containing compounds
  • C08K5/15—Heterocyclic compounds having oxygen in the ring
  • C08K5/151—Heterocyclic compounds having oxygen in the ring having one oxygen atom in the ring
  • C08K5/1535—Five-membered rings

Definitions

• the field of the invention is that of rubber compositions for tire, more specifically rubber compositions for tread.
• a tread must obey in known manner to a large number of technical requirements, often antinomic, among which low rolling resistance, high wear resistance, and a high grip on dry road as wet.
• plasticizers comprising a mixture of non-aromatic oils of the MES or TDAE type and terpene hydrocarbon resins of limonene type, or alternatively hydrocarbon resins of C5 / vinylaromatic cut copolymer or of terpene / vinylaromatic copolymer (see patent applications WO 2005/087859, WO 2006/061064, WO 2007/017060).
• plasticizers comprising a triester of glycerol fatty acid, such as an oil. vegetable sunflower high oleic acid, and a plasticizing hydrocarbon resin.
• the invention therefore relates to a tire whose tread comprises a rubber composition comprising at least:
• thermoplastic hydrocarbon resin solid
• plasticizer liquid
• radicals R 1 and R 2 which are identical or different, independently represent a hydrocarbon radical containing from 1 to 30 carbon atoms.
• a liquid plasticizer as defined above and of natural origin, provides a final composition of rubber, with all its constituents, having a glass transition temperature, before cooking, almost identical to the glass transition temperatures of said compositions obtained with the plasticizer systems used hitherto.
• This type of compound is described in particular in EP 105871 1 or WO 99/045060 as a solvent or plasticizer for thermoplastics such as PVC.
• the invention relates to a tire as defined above in which the radicals R 1 and R 2 , which are identical or different, independently represent a hydrocarbon radical chosen from aliphatic radicals, saturated or unsaturated, linear, branched or cyclic compounds having from 1 to 30 carbon atoms, and aryls, aralkyls or alkaryls having from 6 to 30 carbon atoms.
• the radicals R 1 and R 2 which are identical or different, independently represent a hydrocarbon radical comprising from 2 to 18 carbon atoms, optionally interrupted by one or more heteroatoms.
• radicals R 1 and R 2 are identical.
• the invention relates to a tire as defined above in which the plasticizer based on one or more isosorbide diesters is preferably present in an amount ranging from 5 to 50 phr, and more preferably in an amount ranging from 10 to 30 phr.
• the invention relates to a tire as defined above in which the plasticizer based on isosorbide diester has a glass transition temperature (Tg) of less than 0 ° C, preferably less than -10. ° C and more preferably below -20 ° C and in particular from -30 ° C to -60 ° C.
• Tg glass transition temperature
• the invention relates to a tire as defined above wherein the thermoplastic hydrocarbon resin preferably has a glass transition temperature (Tg) greater than 0 ° C, more preferably greater than 20 ° C.
• the thermoplastic hydrocarbon resin is preferably selected from the group consisting of cyclopentadiene homopolymer or copolymer resins, dicyclopentadiene homopolymer or copolymer resins, terpene homopolymer or copolymer resins, homopolymer resins or the like. C5 cutting copolymer, homopolymer or C9 cut copolymer resins, alpha-methyl-styrene homopolymer or copolymer resins and mixtures of these resins.
• Resin Thermoplastic hydrocarbon is preferably present in an amount of between 5 and 60 phr.
• the invention relates to a tire as defined above in which the diene elastomer is preferably selected from the group consisting of polybutadienes, synthetic polyisoprenes, natural rubber, butadiene copolymers, copolymers of isoprene and mixtures of these elastomers.
• the diene elastomer is preferably selected from the group consisting of polybutadienes, synthetic polyisoprenes, natural rubber, butadiene copolymers, copolymers of isoprene and mixtures of these elastomers.
• the invention relates to a tire as defined above wherein the reinforcing filler comprises carbon black.
• the reinforcing filler comprises an inorganic filler, preferably in an amount of between 30 and 150 phr.
• the tires of the invention are particularly intended to equip tourism-type motor vehicles, SUV ("Sport Utility Vehicles"), two wheels (including motorcycles), aircraft, industrial vehicles chosen from pickup trucks, " Heavy goods vehicles "- that is to say metro, buses, road transport vehicles (trucks, tractors, trailers), off-the-road vehicles such as agricultural or civil engineering vehicles, other transport vehicles or handling.
• SUV Sport Utility Vehicles
• two wheels including motorcycles
• industrial vehicles chosen from pickup trucks, " Heavy goods vehicles "- that is to say metro, buses, road transport vehicles (trucks, tractors, trailers), off-the-road vehicles such as agricultural or civil engineering vehicles, other transport vehicles or handling.
• 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).
• diene elastomer or “diene” rubber must be understood in a known way (one means one or more) elastomer derived at least in part (ie, a homopolymer or a copolymer) of monomers dienes (monomers carrying two double bonds carbon-carbon, conjugated or not). These diene elastomers can be classified in 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 “substantially 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%.
• diene elastomer can be understood more particularly and may be used in the compositions according to the invention:
• a ternary copolymer obtained by copolymerization of ethylene, of an ⁇ -olefin having 3 to 6 carbon atoms with a non-conjugated diene monomer containing from 6 to 12 carbon atoms for example elastomers obtained from ethylene propylene with a non-conjugated diene monomer of the aforementioned type, such as in particular 1,4-hexadiene, ethylidene norbornene, dicyclopentadiene; a copolymer of isobutene and isoprene (butyl rubber), as well as the halogenated versions, in particular chlorinated or brominated, of this type of copolymer.
• 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, an 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-tertiarybutylstyrene, 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, 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.
• Polybutadienes are suitable, in particular those having a content (mol%) in units -1.2 of between 4% and 80% or those having a content (%> molar) of cis-1,4 greater than 80%.
• butadiene-styrene-isoprene copolymers those having a styrene content of between 5% and 50% by weight and more particularly of between 10% and 40% and an isoprene content of between 15% and 50% by weight are particularly suitable.
• the diene elastomer of the composition according to the invention is preferably chosen from the group of diene elastomers.
• strongly unsaturated compounds consisting of polybutadienes (abbreviated "BR"), synthetic polyisoprenes (IR), natural rubber (NR), butadiene copolymers, isoprene copolymers and mixtures of these elastomers.
• BR polybutadienes
• IR synthetic polyisoprenes
• NR natural rubber
• butadiene copolymers are more preferably selected from the group consisting of butadiene-styrene copolymers (SBR), isoprene-butadiene copolymers
• BIR isoprene-styrene copolymers
• SIR isoprene-styrene copolymers
• SBIR isoprene-butadiene-styrene copolymers
• the diene elastomer is predominantly (ie, for more than 50 phr) an SBR, whether it is an emulsion prepared SBR ("ESBR”) or a SBR prepared in solution (“SSBR”), or a blend
• SBR elastomer ESBR or SSBR
• SBR elastomer 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.
• the diene elastomer is predominantly (for more than 50 phr) an isoprene elastomer. This is particularly the case when 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 selected from the group consisting of natural rubber (NR), synthetic polyisoprenes (IR), the various isoprene copolymers and mixtures of these elastomers.
• NR natural rubber
• IR synthetic polyisoprenes
• isoprene copolymers mention will in particular be made of 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; 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 rubber composition comprises a blend of one (or more) diene elastomers said "high Tg” having a Tg between - 70 ° C and 0 ° C and a (one or more) diene elastomers called "low Tg" between -110 ° 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-
• 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, from 30 to 100 phr, in particular from 50 to 100 phr, of a high Tg elastomer in a blend with 0 to 70 phr. , in particular from 0 to 50 phr, of a low Tg elastomer; according to another example, it comprises for all 100 pce one or more SBR prepared (s) in solution.
• the diene elastomer of the composition according to the invention comprises a blend of a BR (as a low Tg elastomer) having a molar ratio (mol%) of cis-1,4 chains higher than 90%, with one or more S-SBR or E-SBR
• compositions of the invention may contain a single diene elastomer or a mixture of several diene elastomers, or the diene elastomers that 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.
• 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 blend of these two types of filler, including a carbon black and silica blend.
• carbon blacks are suitable for all carbon blacks, including black type HAF, ISAF, SAF conventionally used in tires (so-called pneumatic grade black).
• the reinforcing carbon blacks of the 100, 200 or 300 series for example blacks NI 15, N134, N234, N326, N330, N339, N347, 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 the isoprene elastomer in the form of a masterbatch (see for example WO 97/36724 or WO 99/16600).
• organic fillers other than carbon blacks
• organic functionalized polyvinylaromatic fillers as described in applications WO 2006/069792 and WO 2006/069793.
• any inorganic or mineral filler (regardless of its color and origin (natural or synthetic), also called “white” charge, charge “clear” or “charge non noir”(”non-blackfiller") as opposed to carbon black, capable of reinforcing on its own, without any other means an intermediate coupling agent, a rubber composition intended for the manufacture of tires, in other words able to replace, 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 is present indifferent, whether in the form of powder, microbeads, granules, beads or any other suitable densifed form.
• reinforcing inorganic filler also refers to mixtures of different reinforcing inorganic fillers, in particular highly dispersible siliceous and / or aluminous fillers as described below.
• reinforcing inorganic fillers are particularly suitable mineral fillers of the siliceous type, in particular of silica (S1O2), or of the aluminous type, in particular of alumina (Al2O3).
• 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.
• HDS highly dispersible precipitated silicas
• the reinforcing inorganic filler used in particular if it is silica, preferably has a BET surface area between 45 and 400 m 2 / g, more preferably between 60 and 300 m 2 / g.
• 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 the particular applications concerned: the level of reinforcement expected on a bicycle tire, for example, is of course less than that required on a tire capable of driving 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 a truck.
• a reinforcing filler comprising between 30 and 150 phr, more preferably between 50 and 150 phr, and more preferably between 80 and 130 phr of inorganic filler, particularly of silica, is used. 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).
• a coupling agent at least bifunctional to ensure a sufficient connection, chemical and / or physical, between the inorganic filler (surface of its particles) and the diene elastomer, in particular organosilanes or bifunctional polyorganosiloxanes.
• polysulfide silanes called “symmetrical” or “asymmetrical” according to their particular structure, are used, as described for example in the applications WO 03/002648 (or US 2005/016651) and WO 03/002649 (or US Pat. 2005/016650).
• x is an integer of 2 to 8 (preferably 2 to 5);
• - A is a divalent hydrocarbon radical (preferably groups C 1 -C 18 alkylene 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:
• R.1 radicals substituted or unsubstituted, identical or different, represent an alkyl group Ci-Cis cycloalkyl, C5-C18 aryl or C 6 -Ci8 (preferably alkyl, Ci-C 6 , cyclohexyl or phenyl, especially C1-C4 alkyl groups, more particularly methyl and / or ethyl).
• the average value of "x" is a fractional number preferably between 2 and 5 more preferably close to 4.
• polysulphurized silanes By way of examples of polysulphurized silanes, mention may be made more particularly of the polysulfides (in particular disulfides, trisulphides or tetrasulfides) of bis- (C 1 -C 4 alkoxy) -alkyl (C 1 -C 4) silyl-(C 1 -C 4) alkyl. )), such as polysulfides of bis (3-trimethoxysilylpropyl) or bis (3-triethoxysilylpropyl).
• tetrasulfide is used in particular bis (3-triethoxysilylpropyl), abbreviated to TESPT, of formula [(C2H 5 O) 3Si (CH 2 ) 3S 2] 2 or bis (triethoxysilylpropyl) disulfide, abbreviated to TESPD, of formula [(C 2 H 5 0) 3Si (CH2) 3S] 2.
• polysulfides in particular disulphides, trisulphides or tetrasulfides
• polysulfides of bis- (monoalkoxyl (Ci-C 4 ) -dialkyl (Ci-C 4 ) silylpropyl), more particularly bis-monoethoxydimethylsilylpropyl tetrasulfide.
• polysulfides in particular disulphides, trisulphides or tetrasulfides
• bis-monoethoxydimethylsilylpropyl tetrasulfide as described in patent application WO 02/083782 (or US 2004/132880).
• the content of coupling agent is preferably between 4 and 12 phr, more preferably between 3 and 8 phr.
• the rubber composition according to the invention comprises a plasticizer system comprising at least as first plasticizer, a thermoplastic hydrocarbon resin, and at least as a second plasticizer, a plasticizer based on one or more isosorbide diesters of formula (I ) next : in which the radicals R 1 and R 2 , which are identical or different, independently represent a hydrocarbon radical containing from 1 to 30 carbon atoms.
• the first plasticizer still called "plasticizing resin” is reserved in the present application, by definition to hydrocarbon resins, essentially based on carbon and hydrogen but may include other types of atoms, usable in particular as plasticizers or tackifiers in polymeric matrices. They are inherently miscible (i.e., compatible) with the levels used with the polymer compositions for which they are intended, so as to act as true diluents. They have been described, for example, in the book "Hydrocarbon Resins" by R. Mildenberg, M. Zander and G.
• pneumatic rubber 5.5 "Rubber Tires and Mechanical Goods”
• They can be aliphatic, cycloaliphatic, aromatic, hydrogenated aromatic, aliphatic / aromatic type that is to say based on aliphatic and / or aromatic monomers.
• They may be natural or synthetic, whether based on petroleum or not (if so, also known as petroleum resins).
• Their Tg is preferably greater than 0 ° C., especially greater than 20 ° C. (most often between 30 ° C. and 95 ° C.).
• these hydrocarbon resins can also be called thermoplastic resins in that they soften by heating and can be molded. They can also be defined by a point or softening point (in English, "softening point”).
• the softening temperature of a hydrocarbon resin is generally about 50 to 60 ° C. higher than its Tg value.
• the softening point is measured according to ISO 4625 ("Ring and Bail” method).
• Macrostructure (Mw, Mn and Ip) is determined by size exclusion chromatography (SEC) as indicated below.
• the SEC analysis for example, consists in separating the macro molecules in solution according to their size through columns filled with a porous gel; the molecules are separated according to their hydrodynamic volume, the larger ones being eluted first.
• the sample to be analyzed is simply solubilized beforehand in a suitable solvent, tetrahydroiuran at a concentration of 1 g / liter. Then the solution is filtered on a 0.45 ⁇ porosity filter before injection into the apparatus.
• the apparatus used is for example a "Waters alliance" chromatographic chain according to the following conditions: elution solvent: tetrahydrofuran; temperature 35 ° C; concentration 1 g / liter; flow rate: 1 ml / min; injected volume: 100 ⁇ ; Moore calibration with polystyrene standards; set of 3 columns “Waters” in series (“Styragel HR4E", “Styragel HR1” and “Styragel HR 0.5”); detection by differential refractometer (for example "WATERS 2410") that can be equipped with operating software (for example "Waters Millenium”).
• elution solvent tetrahydrofuran
• concentration 1 g / liter
• flow rate 1 ml / min
• injected volume 100 ⁇
• Moore calibration with polystyrene standards set of 3 columns “Waters” in series (“Styragel HR4E”, “Styragel HR1" and “Styragel HR
• a Moore calibration is conducted with a series of commercial standards of polystyrene low Ip (less than 1.2), known molar masses, covering the field of masses to be analyzed.
• the hydrocarbon resin has at least one, more preferably all of the following characteristics:
• Tg greater than 25 ° C (in particular between 30 ° C and 100 ° C), more preferably greater than 30 ° C (in particular between 30 ° C and 95 ° C);
• a softening point greater than 50 ° C. (in particular between 50 ° C. and 150 ° C.); a number-average molar mass (Mn) of between 400 and 2000 g / mol, preferably between 500 and 1500 g / mol;
• Ip Mw / Mn with Mw weight average molar mass
• hydrocarbon resins examples include those selected from the group consisting of cyclopentadiene homopolymer or copolymer resins (abbreviated as CPD), dicyclopentadiene homopolymer or copolymer resins (abbreviated as DCPD), homopolymer or terpene copolymer resins, homopolymer or C5 cut copolymer resins, homopolymer or C9 cut copolymer resins, alpha-methyl-styrene homopolymer or copolymer resins, and mixtures of these resins.
• CPD cyclopentadiene homopolymer or copolymer resins
• DCPD dicyclopentadiene homopolymer or copolymer resins
• homopolymer or terpene copolymer resins homopolymer or C5 cut copolymer resins
• homopolymer or C9 cut copolymer resins alpha-methyl-styrene homopolymer or copolymer
• copolymer resins mention may be made more particularly of those selected from the group consisting of (D) CPD / vinylaromatic copolymer resins, (D) CPD / terpene copolymer resins, terpene phenol copolymer resins, (D) CPD / C5 cut copolymer resins, (D) CPD / C9 cut copolymer resins, terpene / vinylaromatic copolymer resins, terpene / phenol copolymer resins, C5 / vinylaromatic cut copolymer resins, and mixtures of these resins.
• 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. .
• Suitable vinylaromatic monomers are, for example, styrene, alpha-methylstyrene, ortho-methylstyrene, metamethylstyrene, para-methylstyrene, vinyl-toluene, para-tert-butylstyrene, methoxystyrenes, chlorostyrenes, hydroxystyrenes, vinylmesitylene, divinylbenzene, vinylnaphthalene, any vinyl aromatic monomer from a C 9 fraction (or more generally from a C 8 -C 10).
• resins selected from the group consisting of homopolymer resins (D) CPD, copolymer resins (D) CPD / styrene, polylimonene resins, limonene / styrene copolymer resins , limonene / D (CPD) copolymer resins, C5 / styrene cut copolymer resins, C5 / C9 cut copolymer resins, and mixtures of these resins.
• D homopolymer resins
• D copolymer resins
• CPD / styrene polylimonene resins
• limonene / styrene copolymer resins limonene / D (CPD) copolymer resins
• C5 / styrene cut copolymer resins C5 / C9 cut copolymer resins
• the hydrocarbon resin content 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 content of hydrocarbon resin is more preferably between 5 and 40 phr, more preferably between 10 and 30 phr.
• the plasticizer system according to the invention also comprises at least, as second plasticizer (liquid), a plasticizer based on one or more isosorbide diesters of general formula (I):
• radicals R 1 and R 2 which are identical or different, independently represent a hydrocarbon radical containing from 1 to 30 carbon atoms, optionally interrupted by one or more heteroatoms.
• the radicals R 1 and R 2 which are identical or different, independently represent a hydrocarbon radical chosen from aliphatic (especially alkyl), saturated or unsaturated, linear, branched or cyclic radicals containing from 1 to 30 carbon atoms, and aryls, aralkyls or alkaryls having from 6 to 30 carbon atoms.
• the radicals R 1 and R 2 which are identical or different, independently represent a hydrocarbon radical comprising from 2 to 18 carbon atoms, optionally interrupted by one or more heteroatoms.
• radical interrupted by one or more heteroatoms is meant a radical comprising one or more heteroatoms, each heteroatom being between two carbon atoms of said radical, or between a carbon atom of said radical and another heteroatom of said radical or between two other hetero atoms of said radical.
• the heteroatom (s) may be nitrogen, sulfur or oxygen.
• the plasticizer based on isosorbide diester has a glass transition temperature (Tg) of less than 0 ° C., preferably less than -10 ° C. and more preferably less than -20 ° C., and in particular ranging from -30 ° C to -60 ° C.
• Tg glass transition temperature
• plasticizer based on one or more isosorbide diesters of general formula (I) is meant in the sense of the present invention, a liquid plasticizer consisting predominantly of compounds of general formula (I), with a single compound of formula (I) or a mixture of compounds of formula (I).
• Plasticizers based on one or more isosorbide diesters of general formula (I) may be prepared from isosorbide in a manner known to those skilled in the art, by esterification with carboxylic acids, for example fatty acids. Some are also commercially available such as the "Polysorb ID 37" from Roquette.
• the diester according to the invention may be present in an amount ranging from 5 to 50 phr and preferably from 10 to 30 phr. It is recalled that the unit “pc” means "part by weight per hundred parts of elastomer”. Various additives
• the rubber compositions in accordance with the invention may also comprise all or part of the usual additives usually used in elastomer compositions intended for the manufacture of tires or semi-finished products for tires, such as, for example, other plasticizers.
• non-aromatic or very weakly aromatic for example naphthenic, paraffinic oils, MES or TDAE oils, esters (in particular trioleates) of glycerol, in particular natural esters such as vegetable oils of rapeseed or sunflower, pigments, protective agents such as anti-ozone waxes, chemical antiozonants, anti-oxidants, 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, ac vulcanization celerifiers, vulcanization activators, anti-reversion agents.
• compositions can also contain, in addition to the coupling agents, coupling activators, inorganic charge-covering agents or, more generally, processing aid agents that are capable of being used in a known manner, by means of an improvement. of the dispersion of the filler in the rubber matrix and a lowering of the viscosity of the compositions, to improve their processability 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.
• hydrolysable silanes such as alkylalkoxysilanes, polyols, polyethers primary, secondary or tertiary amines, hydroxylated or hydrolyzable polyorganosiloxanes.
• compositions are manufactured in suitable mixers, using two successive preparation phases well known to those skilled in the art: a first phase of work or thermo-mechanical mixing (phase called “nonproductive”) at high temperature, up to a maximum temperature of between 110 ° C. and 190 ° C., preferably between 130 ° C. and 180 ° C., followed by a second mechanical working phase (so-called “phase”).
• productive to a lower temperature, typically below 110 ° C, for example between 40 ° C and 100 ° C, finishing phase during which the crosslinking system is incorporated.
• the process according to the invention for preparing a rubber composition comprises the following steps:
• non-productive Incorporating into a diene elastomer, during a first step (called “non-productive"), at least one reinforcing filler, a plasticizing resin and an ester plasticizer, thermomechanically kneading the whole, in one or more times, until reaching a maximum temperature of 110 ° C to 190 ° C;
• ester plasticizer corresponding to the above formula (I) and, preferably, to the aforementioned preferred characteristics.
• the non-productive phase is conducted in a single thermomechanical step during which is introduced in one or more times, in a suitable mixer such as a conventional internal mixer, at first all the necessary basic constituents (diene elastomer, reinforcing filler and coupling agent if necessary, plasticizers), then in a second step, for example after one to two minutes of mixing, the other additives, any recovery agents or application agents with the exception of the crosslinking system.
• a suitable mixer such as a conventional internal mixer
• the necessary basic constituents diiene elastomer, reinforcing filler and coupling agent if necessary, plasticizers
• a second step for example after one to two minutes of mixing, the other additives, any recovery agents or application agents with the exception of the crosslinking system.
• 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.
• the crosslinking system is preferably a vulcanization system based on sulfur and an accelerator.
• Any compound capable of acting as a vulcanization accelerator for diene elastomers in the presence of sulfur especially those selected from the group consisting of 2-mercaptobenzothiazyl disulfide (abbreviated "MBTS”), N-cyclohexyl-2-benzothiazyl, may be used.
• MBTS 2-mercaptobenzothiazyl disulfide
• N-cyclohexyl-2-benzothiazyl may be used.
• CBS C-bis(trimethyl)-2-benzothiazyl sulfenamide
• DCBS N-dicyclohexyl-2-benzothiazyl sulfenamide
• TBBS N-tert-butyl-2-benzothiazyl sulfenamide
• TBSI N-tert-butyl -2-benzothiazyl sulfenimide
• a primary accelerator of the sulfenamide type is used.
• vulcanization activators such as zinc oxide, stearic acid, guanidine derivatives (in particular diphenylguanidine), etc.
• the sulfur content is for example between 0.5 and 3.0 phr, that of the primary accelerator between 0.5 and 5.0 phr.
• the final composition thus obtained is then calendered, for example in the form of a sheet or a plate, in particular for a characterization in the laboratory, or else extruded in the form of a rubber profile which can be used for example as a tire tread for passenger vehicles.
• the vulcanization (or cooking) is conducted in a known manner at a temperature generally between 130 ° C and 200 ° C, for a sufficient time which may vary for example between 5 and 90 min depending in particular on the cooking temperature. of the vulcanization system adopted and the kinetics of vulcanization of the composition under consideration.
• the invention relates to previously described tires both in the so-called “raw” state (i.e. before firing) and in the so-called “cooked” or vulcanized state (i.e. after vulcanization).
• 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.
• the dynamic properties G * and tan ( ⁇ ) max are measured on a viscoanalyzer (Metravib VA4000), according to the ASTM D5992-96 standard.
• 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 single shear alternating, at a frequency of 10 Hz, under normal temperature conditions (23 °) according to ASTM D1349-99.
• the results exploited are the complex dynamic shear modulus (G *) and the loss factor tan ( ⁇ ).
• the maximum value of tan ( ⁇ ) observed (tan ( ⁇ ) max) is given between the values at 0.15% and at 50%> deformation.
• the value of tan ( ⁇ ) max (according to a "deformation" sweep at a temperature of 23 ° C.) is representative of the hysteresis and the rolling resistance (plus tan ( ⁇ ) max) is low, the hysteresis is lower and therefore the rolling resistance).
• the module G * is representative of the rigidity.
• Theromechanical 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.
• 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 measuring their physical or mechanical properties, or extruded in the form of tire treads tourism.
• This test aims to demonstrate the improved performance of rubber compositions according to the invention, compared to control compositions of the prior art.
• six compositions based on diene elastomers SBR, reinforced with silica and carbon black, the formulation of which is suitable for the manufacture of tire treads are prepared.
• compositions tested are identical to nature near one of their components (second plasticizer, liquid):
• compositions 1, 2 and 3 (prior art): liquid plasticizer: sunflower oil;
• Composition 4, 5 and 6 (according to the invention): liquid plasticizer: plasticizer based on one or more isosorbide diesters.
• the plasticizer based on one or more isosorbide diesters used according to the invention is marketed by Roquette essentially for the plasticization of PVC.
• compositions 1, 2 and 3 are reference compositions for the applicants, having also proven their excellent performance in terms of resistance to wear or abrasion on the one hand, and rolling resistance, on the other hand.
• Table 1 gives the formulation of the six compositions (1, 2 and 3 of the prior art) and (4, 5 and 6 of the invention), in part by weight "phr”.
• Plasticizer based on one or more isosorbide diesters "Polysorb ID 37" from Roquette;
• the total amount of plasticizer was adjusted in the compositions according to the invention in order to maintain the rigidity (Shore hardness) treads at a substantially constant level for a good comparison of tire performance.
• Table 2 gives the properties observed on the six compositions (1, 2 and 3 of the prior art) and (4, 5 and 6 of the invention) after baking (30 min at 150 ° C.
• compositions according to the invention compared to the control compositions (with identical concentration in plasticizer system), have the following characteristics:
• the use of the plasticizer system according to the invention provides a gain in rolling resistance without penalizing the other properties that are the wear resistance and road behavior, or even improving them.

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