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
• • 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
• • 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
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/34—Silicon-containing compounds
  • C08K3/36—Silica
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2205/00—Polymer mixtures characterised by other features
  • C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group

Definitions

• the present invention relates to a crosslinked or crosslinked rubber composition which can be used to constitute a tire casing tread having improved wear resistance, such a tread and a tire casing incorporating this tread.
• the invention applies in particular to tires of the passenger or heavy goods vehicle type.
• European patent document EP-A-1 035 164 thus describes a rubber composition for a tire tread which is intended to improve the grip on dry ground of the tire incorporating it.
• this composition comprises a liquid elastomer consisting of a polybutadiene, the vinyl chain content of which varies from 40 to 95%, the number average molecular weight of which can reach 20,000 g / mol and the glass transition temperature Tg can vary from -40 ° C to -5 ° C.
• This composition further comprises a plasticizing resin whose softening temperature varies from 30 ° C to 200 ° C.
• the US patent document US-B-6 204 320 also describes a rubber composition for a tire tread which is intended to improve the grip of the tire incorporating it.
• This composition comprises a liquid elastomer made up of a copolymer of isoprene and butadiene, the number average molecular mass of which can reach 50,000 g / mol and the glass transition temperature Tg of which can vary from -50 ° C. to 20 ° C.
• This composition further comprises an aromatic plasticizing oil and a plasticizing resin.
• the US patent document US-A-4 866 131 also describes a rubber composition for a tire tread intended to improve the grip of the latter, comprising a copolymer of an aliphatic diene and a vinyl aromatic monomer whose number average molecular mass can also reach 50,000 g / mol.
• the object of the present invention is to provide a crosslinkable or crosslinked rubber composition which can be used to constitute a tire casing tread having improved wear resistance, and it is achieved in that the applicants come from surprisingly discover that a diene elastomer of average molecular mass in number Mn of less than 2000 g / mol which exhibits a glass transition temperature Tg greater than -25 ° C.
• diene elastomer in known manner an elastomer derived at least in part (homopolymer or copolymer) from diene monomers (monomers carrying two carbon-carbon double bonds, conjugated or not).
• the or each diene elastomer of the composition according to the invention is preferably "highly unsaturated", that is to say that it is derived from conjugated diene monomers having a molar level of units derived from conjugated dienes which is greater than 50%.
• said elastomer has a number-average molecular mass Mn ranging from 500 g / mol to 1500 g / mol.
• said elastomer has a polymolecularity index Ip of less than 2 and, even more preferably, an Ip index of less than 1.5, or even less than 1.2. Also preferably, said elastomer has a glass transition temperature
• Tg ranging from -15 ° C to 10 ° C.
• said diene elastomer comprises said units resulting from the polymerization of a vinyl aromatic monomer, such as styrene, according to a mass fraction ranging from 10% to 80% and, even more preferably, according to a mass fraction ranging from 30 % to 70%.
• said diene elastomer belongs to the group consisting of copolymers of styrene and butadiene prepared in solution, terpolymers of styrene, butadiene and isoprene prepared in solution and copolymers of styrene and isoprene prepared in solution .
• said diene elastomer is a copolymer of styrene and butadiene prepared in solution comprising said units resulting from the polymerization of styrene according to a mass fraction of between 40% and 60%.
• said diene elastomer comprises units resulting from the polymerization of butadiene, the mass fraction of which in vinyl chains is between 45% and 65%.
• said composition further comprises an elastomer matrix in which said diene elastomer of molecular weight Mn less than 2000 g / mol is miscible and, preferably, said matrix comprises:
• one or more diene elastomers each having a temperature Tg between -110 ° C and -80 ° C.
• each diene elastomer of temperature Tg between -65 ° C and -10 ° C belongs to the group consisting of copolymers of styrene and butadiene prepared in solution, copolymers of styrene and butadiene prepared in emulsion, natural polyisoprenes , synthetic polyisoprenes having a cis-1,4 chain rate greater than 95%, terpolymers of styrene, butadiene, isoprene and by a mixture of these elastomers, and
• each diene elastomer of temperature Tg between -110 ° C and -80 ° C and, preferably, between -105 ° C and -90 ° C comprises polybutadiene units according to a mass fraction equal to or greater than 70 %, and it advantageously consists of a polybutadiene with a cis-1,4 chain rate greater than 90%.
• said or each diene elastomer of Tg comprised between -65 ° C and -10 ° C belongs to the group consisting of styrene / butadiene copolymers prepared in Tg solution comprised between -50 ° C and -15 ° C and with styrene / butadiene copolymers prepared in Tg emulsion between -60 ° C and -30 ° C.
• said composition comprises said diene elastomer (s) of Tg between -65 ° C and -10 ° C in an amount of 100 phr.
• said composition comprises cutting said diene elastomer (s) of Tg between -65 ° C and -10 ° C and said diene elastomer (s) of Tg between -110 ° C and -80 ° C.
• said composition comprises a blend of at least one copolymer of styrene and butadiene prepared in solution, as diene elastomer of Tg of between -65 ° C and - 10 ° C, and at least one polybutadiene having a rate of cis-1,4 linkages greater than 90%, as diene elastomer of Tg between -110 ° C and -80 ° C.
• said composition comprises a blend of at least one copolymer of styrene and butadiene prepared as an emulsion, as diene elastomer of Tg of between -65 ° C and - 10 ° C, and at least one polybutadiene having a rate of cis-1,4 linkages greater than 90%, as diene elastomer of Tg between -110 ° C and -80 ° C.
• copolymer of styrene and butadiene prepared as an emulsion it is advantageous to use copolymers having an amount of emulsifier varying substantially from 1 phr to 3.5 phr, for example the E-SBR copolymers comprising 1.7 phr and 1.2 phr of emulsifier which are both described in European patent document EP-A-1 173 338 (see paragraph I. of the examples of embodiments contained in the description of this application).
• said composition comprises said diene elastomer of molecular mass Mn of less than 2000 g / mol in an amount ranging from 10 phr to 50 phr and, even more preferably, in an amount ranging from 30 pce to 45 pce.
• said composition further comprises, in an amount ranging from 20 phr to 40 phr, a plasticizing resin of number average molecular mass ranging from 400 to 2000 g / mol and of transition temperature vitreous above 50 ° C and below 120 ° C which comprises, according to a mass fraction ranging from 70% to 100%, units resulting from the polymerization of a monocyclic or bicyclic unsaturated terpene.
• a plasticizing resin of number average molecular mass ranging from 400 to 2000 g / mol and of transition temperature vitreous above 50 ° C and below 120 ° C which comprises, according to a mass fraction ranging from 70% to 100%, units resulting from the polymerization of a monocyclic or bicyclic unsaturated terpene.
• said resin has a number average molecular weight ranging from 500 to 1000 g / mol and, even more preferably, ranging from 550 to 700 g / mol.
• said resin has a glass transition temperature ranging from 60 ° C to 100 ° C.
• said resin has a polymolecularity index of less than 2.
• said resin comprises said units resulting from the polymerization of a monocyclic or bicyclic unsaturated terpene according to a mass fraction ranging from 90% to 100%.
• said unsaturated terpene from which the resin is predominantly or wholly derived is a monocyclic unsaturated terpene, preferably a limonene (ie 1-methyl-4-isopropenyl cyclohexene) such as d-limonene (enantiomer dextrorotatory) or dipentene (racemic of the dextrorotatory and levorotatory enantiomers of limonene).
• a limonene ie 1-methyl-4-isopropenyl cyclohexene
• d-limonene enantiomer dextrorotatory
• dipentene racemic of the dextrorotatory and levorotatory enantiomers of limonene
• said resin further comprises one or more units derived from at least one hydrocarbon or non-hydrocarbon monomer which is not a monocyclic unsaturated terpene and which advantageously belongs to the group consisting by a bicyclic unsaturated terpene such as a -pinene (ie 2,6,6-trimethylbicycIo [3.1.1] hept-2-ene), a monocyclic or polycyclic aromatic hydrocarbon such as styrene or an alkyl styrene, a diene cyclic such as dicyclopentadiene, and a conjugated diene such as isoprene.
• a bicyclic unsaturated terpene such as a -pinene (ie 2,6,6-trimethylbicycIo [3.1.1] hept-2-ene)
• a monocyclic or polycyclic aromatic hydrocarbon such as styrene or an alkyl styrene
• diene cyclic such
• This monomer can also consist of acrylonitrile or also methyl methacrylate.
• resins sold by the company DRT under the name “Dercolyte L120” and by the company ARIZONA under the names “Sylvares TR7125” and “Sylvagum TR7125C", which all include units resulting from the polymerization of d-limonene or dipentene according to a mass fraction of between 90% and 100%.
• said resin consists of said units resulting from the homopolymerization of said monocyclic unsaturated terpene.
• a resin resulting entirely from the homopolymerization of d-limonene or dipentene preferably a resin of average molecular weight ranging from 550 g / mol to 650 g / mol and a glass transition temperature ranging from 60 ° C to 80 ° C.
• d-limonene is a natural extract (it occurs naturally in the skin of oranges) and that, consequently, the plasticizing resin resulting from the homopolymerization of this d-limonene is of exclusively origin natural, which contributes to reducing environmental pollution when rolling tires whose treads incorporate this resin.
• said unsaturated terpene from which the resin is predominantly or completely derived is a bicyclic unsaturated terpene, preferably an ⁇ -pinene.
• said resin further comprises one or more units derived from at least one hydrocarbon or non-hydrocarbon monomer which is not a bicyclic unsaturated terpene and which advantageously belongs to the group formed by a monocyclic unsaturated terpene such as a limonene or dipentene, a monocyclic or polycyclic aromatic hydrocarbon such as styrene or an alkyl styrene, a cyclic diene such as dicyclopentadiene, and a conjugated diene such as isoprene.
• said resin consists of said units resulting from the polymerization of said bicyclic unsaturated terpene, such as ⁇ -pinene.
• the composition according to the invention comprises, in an amount ranging from 20 phr to 25 phr, said diene elastomer of molecular mass Mn of less than 2000 g / mol and, in an amount ranging from 10 phr to 15 phr, said resin plasticizing.
• said rubber composition also comprises at least one plasticizing oil extracted from petroleum which is of the paraffinic type, aromatic or naphthenic, in an amount ranging from 0 phr to 25 phr and, preferably, ranging from 0 phr to 15 phr.
• said rubber composition is completely devoid of any plasticizing oil extracted from petroleum.
• the improvement in the wear resistance which said diene elastomer of molecular mass Mn of less than 2000 g / mol and possibly said resin gives to the tire casing according to the invention implies a reduction in compaction over time. by compression to which the tread according to the invention is subjected during rolling and, consequently, a reduction in time of the loss in rolling of the plasticizing oil extracted from the petroleum possibly present, such as aromatic oil.
• composition according to the invention also comprises a reinforcing filler, in an amount which can vary from 50 to 150 phr.
• said reinforcing filler comprises an inorganic reinforcing filler according to a mass fraction ranging from 50% to 100%.
• the term “reinforcing inorganic filler” is understood, in known manner, an inorganic or mineral filler, whatever its color and its origin (natural or synthetic), also called “white” filler or sometimes “clear” filler "in contrast to carbon black, this inorganic filler being capable of reinforcing on its own, without 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 charge of pneumatic grade carbon black.
• said reinforcing inorganic filler is, in whole or at least mainly, silica (SiC> 2).
• the silica used can be any reinforcing silica known to those skilled in the art, in particular any precipitated or pyrogenic silica having a BET surface as well as a CTAB specific surface, both less than 450 m 2 / g, even if the highly dispersible precipitated silicas are preferred.
• a silica having BET or CTAB specific surfaces which both range from 80 m 2 / g to 260 m 2 / g.
• the BET specific surface is determined in a known manner, according to the Brunauer-Emmet-Teller method described in "The Journal of the American Chemical Society” Flight. 60, page 309, February 1938 and corresponding to the standard APNOR-NFT-45007 (November 1987); the CTAB specific surface is the external surface determined according to the same standard AFNOR-NFT-45007 of November 1987.
• highly dispersible silica means any silica having a very high ability to disaggregate and to disperse in an elastomer matrix, observable in known manner by electron or optical microscopy, on fine sections.
• preferential highly dispersible silicas mention may be made of the Ultrasil 7000 and Ultrasil 7005 silicas from the company Degussa, the Zeosil 1165MP, 1135MP and 1115MP silicas from the company Rhodia, the Hi-Sil EZ150G silica from the company PPG, Zeopol silicas 8715, 8745 and 8755 from the company Huber, treated precipitated silicas such as, for example, silicas "doped” with aluminum described in application EP-A-735 088.
• reinforcing inorganic filler is also understood to mean mixtures of various reinforcing inorganic fillers, in particular highly dispersible silicas as described above.
• reinforcing inorganic filler it is also possible to use, without limitation:
• aluminas of formula A1 2 0 3 ), such as aluminas with high dispersibility which are described in the European patent document EP-A-810 258, or also
• reinforcing inorganic fillers comprising carbon blacks modified with silica
• the fillers which are marketed by the company CABOT under the name "CRX 2000”, and which are described in the patent document international WO-A-96/37547.
• said reinforcing filler comprises carbon black in a mass fraction ranging from 50% to 100%. All the carbon blacks conventionally used in tire casings and in particular in the treads of such casings, in particular blacks of the HAF, ISAF, SAF type, are suitable. Mention may be made, without limitation, of the blacks NI 15, N134, N234, N339, N347, N375.
• said reinforcing filler comprises cutting said reinforcing inorganic filler with carbon black, the mass fraction of carbon black in said reinforcing filler preferably being chosen to be less than or equal to 50% .
• black / silica blends or blacks partially or completely covered with silica are suitable for constituting the reinforcing filler.
• the rubber composition according to the invention additionally conventionally comprises a reinforcing inorganic filler / elastomer matrix (also called coupling agent) bonding agent, which has the function of ensuring a sufficient bonding (or coupling), of a chemical nature. and / or physical, between said inorganic charge and the matrix, while facilitating the dispersion of this inorganic charge within said matrix.
• a reinforcing inorganic filler / elastomer matrix also called coupling agent
• Coupled agent is understood to mean more specifically an agent capable of establishing a sufficient connection, of chemical and / or physical nature, between the filler considered and the elastomer, while facilitating the dispersion of this filler within the elastomer matrix.
• a coupling agent at least bifunctional, has for example as simplified general formula "Y-T-X", in which:
• Y represents a functional group ("Y" function) which is capable of physically and / or chemically binding to the inorganic charge, such a bond being able to be established, for example, between a silicon atom of the coupling agent and hydroxyl groups
• (OH) surface of the inorganic filler for example surface silanols when it is silica
• - X represents a functional group (function "X") capable of physically and / or chemically bonding to the elastomer, for example by means of a sulfur atom;
• - T represents a group making it possible to connect Y and X.
• Coupling agents should in particular not be confused with simple agents for recovery of the charge considered which, in known manner, may include the function Y active with respect to the charge but are devoid of the function X active vis -to the elastomer.
• Such coupling agents have been described in a very large number of documents and are well known to those skilled in the art. Any coupling agent known for, or capable of ensuring effectively, in diene rubber compositions which can be used for the manufacture of tires, the binding or coupling between a reinforcing inorganic filler such as silica and a diene elastomer can be used.
• organosilanes such as, for example, organosilanes, in particular polysulphurized alkoxysilanes or mercaptosilanes, or alternatively polyorganosiloxanes carrying the abovementioned X and Y functions.
• Silica / elastomer coupling agents in particular, have been described in a large number of documents, the best known being bifunctional alkoxysilanes such as polysulphurized alkoxysilanes.
• - n is an integer from 2 to 8 (preferably from 2 to 5);
• - A is a divalent hydrocarbon radical (preferably alkylene groups in
• R2 R2 R2 in which:
• radicals R i substituted or unsubstituted, identical or different from each other, represent a C ⁇ -C 18 alkyl group, C 5 -Ci8 cycloalkyl or C ⁇ -Ci aryl group, (preferably Ci-Ce alkyl groups . cyclohexyl or phenyl, in particular alkyl CC 4, more particularly methyl and / or ethyl).
• R radicals substituted or unsubstituted, identical or different, represent an alkoxyl group C_-C_ g or cycloalkoxyl C -C ⁇ 8 (preferably alkoxyl groups or CC 8 cycloalkoxy, C 5 -C 3, more preferably CC 4 alkoxyl groups, in particular methoxyl and / or ethoxyl).
• n is a fractional number, preferably included in a field from 2 to 5.
• polysulphurized alkoxysilanes there may be mentioned more particularly polysulphides (in particular disulphides, trisulphides or tetrasulphides) of bis- (alkoxyl (C ⁇ -C 4 ) -alkyl (C ⁇ - C 4 ) silylalkyl (C ⁇ -C 4 )), for example bis (3-trimethoxysilylpropyl) or bis (3-triethoxysilylpropyl) polysulphides.
• TESPD bis (3-triethoxysilylpropyl) tetrasulfide, in short TESPT, of formula [(C 2 H 5 ⁇ ) 3Si (CH 2 ) 3 S 2 ] 2 or bis (triethoxysilylpropyl) disulfide, is used in particular abbreviated TESPD, of formula [(HsO ⁇ S ⁇ CHz ⁇ Slz.
• TESPD is marketed for example by the company Degussa under the names Si266 or Si75 (in the second case, in the form of a disulfide mixture (at 75% by weight) and of polysulphides), or by the company Witco under the name Silquest Al 589.
• TESPT is marketed for example by the company Degussa under the name Si69 (or X50S when it is supported at 50% by weight on carbon black), or by the company Osi Specialties under the name Silquest A1289 (in both cases, commercial mixture of polysulphides with an average value for n close to 4). Mention will also be made of monoalkoxysilanes tetrasulphides, such as tetrasulphide monoethoxydimethylsilylpropyl (in abbreviated MESPT), which are the subject of international patent application PCT / EP02 / 03774 in the name of the applicants.
• MESPT tetrasulphide monoethoxydimethylsilylpropyl
• the or at least one of the diene elastomers which can be used in the composition according to the invention may comprise one or more functional groups specifically active for coupling to said reinforcing filler.
• the functional groups, coupled or stars, which are known to a person skilled in the art for coupling to silica are suitable. Without limitation, agree:
• Such groups can be obtained as known per se by reaction with a functionalizing agent of the organohalo-tin type which can correspond to the general formula R 3 SnCl, or with a coupling agent of the organodihalo-tin type which can correspond to the general formula R 2 SnCl 2 , or with a star-forming agent of organotrihalo-tin type which can correspond to the general formula RSnCl 3 , or of tetrahalo-tin type which can correspond to the formula SnCl 4 (where R is an alkyl, cycloalkyl or aryl radical).
• compositions in accordance with the invention also comprise, in addition to said elastomer matrix, said diene elastomer of mass Mn of less than 2000 g / mol, optionally said plasticizing oil and / or said plasticizing resin, said reinforcing filler and optionally said binding agent, any or part of the other constituents and additives usually used in rubber compositions, such as pigments, antioxidants, anti-ozone waxes, a crosslinking system based on sulfur and / or peroxide and / or bismaleimides, one or more reinforcing agents for the reinforcing inorganic filler such as alkylalkoxysilanes, polyols, amines or amides.
• said plasticizing oil and / or said plasticizing resin optionally said plasticizing oil and / or said plasticizing resin
• said reinforcing filler and optionally said binding agent any or part of the other constituents and additives usually used in rubber compositions, such as pigments, antioxidants, anti-ozone wax
• compositions in accordance with the invention can be prepared according to known methods of thermomechanical working of the constituents in one or more stages.
• a tire casing tread according to the invention is such that it comprises said rubber composition according to the invention.
• a tire casing according to the invention comprises this tread.
• Size exclusion chromatography or SEC allows physical separation of the macromolecules according to their size in the inflated state on columns filled with porous stationary phase. The macromolecules are separated by their hydrodynamic volume, the largest being eluted first. Without being an absolute method, the SEC makes it possible to apprehend the molecular mass distribution of low-weight diene elastomers. From commercial standard products of low molecular weight polystyrene (between 104 and 90,000 g / mol), the various average masses in number Mn and in weight Mp are determined and the polydispersity index Ip calculated. Each low weight elastomer sample is dissolved in tetrahydrofuran at a concentration of approximately 1 g / l.
• the apparatus used is a “WATERS, Alliance 2690 model” chromatograph.
• the elution solvent is tetrahydrofuran (mobile phase), the flow rate of 1 ml / min., The system temperature of 35 ° C and the analysis time of 40 min.
• For the stationary phase a set of three columns in series is used, with respective trade names "WATERS type STYRAGEL HR4E" (mixed bed column), "WATERS type STYRAGEL HR1" (porosity 100 Angstrom) and "WATERS STYRAGEL HR0.5 »(Porosity 50 Angstrom).
• the volume injected with the solution of each elastomer sample is 100 ⁇ l.
• the detector is a "WATERS model 2410" differential refractometer and the operating software for the chromatographic data is the “WATERS MILLENIUM” system (version 3-2). Measurement of the glass transition temperatures of all the elastomers:
• the glass transition temperatures Tg of the elastomers were measured using a differential scanning calorimeter. Concerning the Tg measurements for the rubber compositions incorporating these elastomers, dynamic measurements were carried out at a frequency of 10 Hz and under two different stress values (0.2 MPa and 0.7 MPa), “MDC” measurements. performed in accordance with ISO standard 4664 (the deformation mode being shearing and the test pieces being cylindrical).
• Hysteretic losses (PH): measured in% by rebound at 60 ° C on the sixth shock, according to the following relationship: PH (%) 100 x (W 0 -W ⁇ ) / W ⁇ , with W 0 : energy supplied and Wi: energy returned.
• PH (%) 100 x (W 0 -W ⁇ ) / W ⁇ , with W 0 : energy supplied and Wi: energy returned.
• Relative performance indices were used, compared to a reference index 100 characterizing a “control” envelope (a performance index greater than this base 100 reflecting a performance greater than that of the corresponding “control” envelope ).
• each of the envelopes tested was measured by rolling on a steering wheel, at an ambient temperature of 25 ° C, under a load of 392 daN and at a speed of 80 km / h, the internal pressure of the envelope being 2.1 bars, for envelopes of dimensions 175/70 R14 "MXT".
• the wear resistance of each envelope was determined by means of a relative wear index which is a function of the remaining rubber height, after driving on a hazy road circuit, at an average speed of 77 km / h and until wear reaches the wear indicators arranged in the grooves of the treads. This relative wear index was obtained by comparing the remaining rubber height of a tread according to the invention with the remaining rubber height of a "control" tread, which by definition has an index of wear of 100.
• the grip of each tire casing tested was assessed by measuring the braking distances in "ABS” braking mode, both on dry and wet ground. More precisely, the braking distance in "ABS” mode was measured, on dry ground, passing from a speed of 70 km h to 20 km / h and, on wet ground (polished concrete ground with 2 mm height surface water), going from a speed of 40 km / h to 10 km / h.
• a “control” rubber composition T1 and two rubber compositions according to invention II and not in accordance with invention II ' were prepared, each intended to constitute a tread for a tire of the “touring” type. ".
• the following table 1 contains: the formulation of each of these compositions T1, II and II '; the properties of each composition T1, II and II 'in the unvulcanized and vulcanized state; the performance of tires, the respective treads of which consist of these compositions T1, II and II '.
• - S-SBR A is a copolymer of styrene and butadiene prepared in solution having: a rate of 1,2 chains of 58%, a rate of styrenic chains of 25%, a Mooney viscosity ML (l + 4) at 100 ° C equal to 54, an amount of oil equal to 37.5 pce, and a glass transition temperature Tg of -29 ° C.
• - BR A is a polybutadiene having: a very high rate of cis-1,4 linkages, of approximately 93%, and a glass transition temperature Tg of -103 ° C and a Mooney viscosity ML (l + 4) at 100 ° C equal to 54.
• - BP1 is a low-weight diene elastomer according to the invention consisting of a styrene / butadiene copolymer having: a rate of 1,2 chains of 54% and of styrene chains of 50%, of molecular weights Mn and Mw 1300 g / mol and 1500 g / mol respectively, and a glass transition temperature Tg of -14 ° C.
• - BP2 is a low-weight diene elastomer not in accordance with the invention because of its Mn value greater than 2000 g / mol, consisting of a styrene / butadiene copolymer, having: a rate of 1.2 chains of 62% and styrenic sequences of 25%, molecular weights Mn and Mw respectively of 5075 g / mol and 10100 g / mol, and a glass transition temperature Tg of -16 ° C.
• - 6PPD is N- (1,3-dimethyl-butyl) -N'-phenyl-p-phenylenediamine
• the Tg of compositions II, I'I under a dynamic modulus of high modulus are provided for substantially equal to the corresponding Tg of the “control” composition Tl.
• Table 1 the difference between the Tg of compositions II and Tl which have been measured under a dynamic stress of reduced modulus, equal to 0.2 MPa, is very close to the difference between the Tg of the same compositions II and Tl which have been measured under said high modulus constraint.
• the difference between the Tg of compositions II 'and Tl which have been measured under said dynamic stress of reduced modulus is significantly different from the difference between the Tg of the same compositions II' and Tl which have been measured under said stress high modulus.
• Table 1 shows that the low-weight diene elastomers BP1 and BP2 respectively give compositions II and II 'substantially the same mechanical and dynamic properties as those of the “control” composition T1.
• composition II gives the envelopes whose treads are made of this composition a very improved wear resistance compared to that of the “control” composition.
• Tl comprising, as plasticizer, an aromatic oil in place of BP1, while practically retaining the adhesion and rolling resistance performances of the envelopes incorporating said composition Tl and maintaining or improving the mechanical properties (Scott breaking) of said composition Tl.
• composition II does not include aromatic oil, unlike composition Tl, which contributes to environmental protection.
• a T2 “control” rubber composition and two rubber compositions according to the invention 12 and not in accordance with the invention 12 ′ were prepared, each intended to constitute a tread of a tire envelope of the “touring” type. ".
• Table 2 below contains: the formulation of each of these compositions T2, 12 and 12 ′; the properties of each composition T2, 12 and 12 ′ in the unvulcanized and vulcanized state; the performance of tires whose respective treads are made up of these compositions T2, 12 and 12 ′.
• S-SBR A, BR A and BP1 are as defined in Example 1 and BP3 is a low-weight diene elastomer not in accordance with the invention because of its Tg less than -25 ° C, BP3 being a homopolymer of butadiene (rate of styrene sequences of 0%) exhibiting: a high rate of sequences 1.2 (equal to 71%); molecular masses Mn and Mw of 750 g / mol and 810 g / mol respectively, and a glass transition temperature Tg of -65 ° C.
• compositions 12, l'2 under a dynamic stress of high modulus are provided for substantially equal to the corresponding Tg of the “control” composition T2.
• Table 2 shows that the low-weight diene elastomers BP1 and BP3 respectively confer on compositions 12 and 12 ′ substantially the same mechanical and dynamic properties as those of the “control” composition T2.
• composition 12 only the incorporation of the elastomer BP1 according to the invention into composition 12 gives envelopes whose treads made of this composition a very improved resistance to wear compared to that of the “control” composition. »T2 comprising, as plasticizer, an aromatic oil in place of BPl, while practically retaining the adhesion and rolling resistance performance of the envelopes incorporating said composition T2 and by maintaining or improving the mechanical properties (Scott breaking) said composition T2.
• This is not the case with the incorporation of the BP3 elastomer into composition 12 ′.
• composition 12 does not include aromatic oil, unlike composition T2, which contributes to environmental protection.

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• 2003
  • 2003-08-22 EP EP03794921A patent/EP1539878A1/fr not_active Withdrawn
  • 2003-08-22 WO PCT/EP2003/009333 patent/WO2004024813A1/fr not_active Ceased
  • 2003-08-22 JP JP2004535141A patent/JP4642468B2/ja not_active Expired - Fee Related
  • 2003-08-22 CN CNB038247909A patent/CN100567381C/zh not_active Expired - Fee Related
  • 2003-08-22 AU AU2003266306A patent/AU2003266306A1/en not_active Abandoned
  • 2003-08-22 BR BR0306316-0A patent/BR0306316A/pt not_active Application Discontinuation
• 2005
  • 2005-03-10 US US11/076,285 patent/US7329704B2/en not_active Expired - Fee Related

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