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
  • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
  • C08K5/0016—Plasticisers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
  • B60C1/0016—Compositions of the tread
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • 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
• • 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
  • 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
  • C08L45/00—Compositions of homopolymers or copolymers of compounds having no unsaturated aliphatic radicals in side chain, and having one or more carbon-to-carbon double bonds in a carbocyclic or in a heterocyclic ring system; Compositions of derivatives of such polymers
• • 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

Definitions

• EP-A-1 063 246, EP-A-1 029 873, EP-A-990 669 and EP-Al 077 223 also describe rubber compositions for tire tread which are intended to improve the grip of the tires incorporating them.
• These rubber compositions each comprise a polymer resin obtained by copolymerization of four monomers consisting of dicyclopentadiene or dimethyldicyclopentadiene, limonene, a polycyclic aromatic hydrocarbon (indene) and a monocyclic aromatic hydrocarbon (alkyl styrene or vinyl toluene) .
• the respective mass fractions of the four aforementioned monomers are either 25%, 25%, 25%, 25%, or 12.5%, 37.5%, 25%, 25%.
• tread compositions of amorphous or semi-crystalline polymers having a high glass transition (Tg) or melting temperature and a reduced molecular weight use which has the effect of improve the grip on dry or wet ground of the corresponding tires but also penalize their resistance to wear.
• the object of the present invention is to provide a crosslinkable or crosslinked rubber composition which can be used to constimate a tire casing tread having improved wear resistance, and it is achieved in that the applicant has just surprisingly discover that a plasticizing resin of number average molecular mass ranging from 400 to 2000 g / mol, which comprises units resulting from the polymerization of vinylcyclohexene, gives a tire casing of which the tread consists of a rubber composition incorporating this resin, an improved wear resistance compared to that of known casings, the tread of which comprises a plasticizing oil as plasticizer, while giving this casing according to the invention a rolling resistance and grip on dry and wet soils which is close to those of these same known envelopes.
• a plasticizing resin of number average molecular mass ranging from 400 to 2000 g / mol which comprises units resulting from the polymerization of vinylcyclohexene
• the plasticizing resin according to the invention makes it possible to confer improved endurance on the tire casing incorporating it in its tread, insofar as it improves the resistance of the casing to the separation of the top plies of triangulation that it includes in its crown reinforcement.
• said resin has a number average molecular weight ranging from 500 to 1500 g / mol and, even more preferably, ranging from 550 to 1000 g / mol.
• said resin has a glass transition temperature ranging from 50 ° C to 120 ° C and, even more preferably, ranging from 60 ° C to 100 ° C. Even more preferably, said resin has a temperature of glass transition from 70 to 90 ° C.
• said resin further comprises one or more other units, at least one of which results from the polymerization of a monocyclic or bicyclic unsaturated terpene.
• ⁇ -pinene i.e. 2,6,6-trimethylbicyclo [3.1. L] hept-2-ene
• said resin further comprises one or more other units, at least one of which results from the polymerization of a monocyclic or polycyclic aromatic hydrocarbon, such as styrene or an alkyl styrene.
• said resin also comprises one or more other units, at least one of which results from the polymerization of a cyclic diene, such as dicyclopentadiene.
• said resin further comprises one or more other units, at least one of which results from the polymerization of a conjugated diene such as isoprene, acrylonitrile or else methyl methacrylate.
• said rubber composition is based on one or more diene elastomers each derived from at least one conjugated diene monomer having a molar level of units derived from conjugated dienes which is greater than 50%, and this composition comprises said resin in a mass fraction ranging from 10 to 35 phr and, even more preferably, in an amount ranging from 15 to 25 phr (phr: parts by weight per hundred parts of diene elastomer (s) ( s)).
• said rubber composition comprises:
• diene elastomers each having a glass transition temperature between -65 ° C and -10 ° C, and
• one or more diene elastomers each having a glass transition temperature between -110 ° C and -80 ° C.
• Said diene elastomer or elastomers the glass transition temperature of which is between -65 ° C and -10 ° C belong to the group consisting of styrene and butadiene copolymers prepared in solution, styrene and butadiene copolymers prepared in emulsion, natural polyisoprenes, synthetic polyisoprenes with a cis-1,4 chain rate greater than 95%, butadiene and isoprene copolymers (BIR), styrene and isoprene copolymers (SIR), terpolymers styrene, butadiene, isoprene (SBIR) and a mixture of these elastomers.
• BIR butadiene and isoprene copolymers
• SIR styrene and isoprene copolymers
• SBIR terpolymers styrene, butadiene, isoprene
• Said or each diene elastomer whose glass transition temperature is between -110 ° C and -80 ° C (preferably between -105 ° C and -90 ° C) comprises butadiene units at a rate equal to or greater than 70% and preferably consists of a polybutadiene having a cis-1,4 linkage rate greater than 90%.
• said rubber composition comprises, as diene elastomer (s) whose glass transition temperature is between -65 ° C and -10 ° C, at least a copolymer of styrene and butadiene prepared in solution which has a glass transition temperature between -50 ° C and -15 ° C, or a copolymer of styrene and butadiene prepared in emulsion having a glass transition temperature between -65 ° C and -30 ° C.
• diene elastomer whose glass transition temperature is between -65 ° C and -10 ° C
• a copolymer of styrene and butadiene prepared in solution which has a glass transition temperature between -50 ° C and -15 ° C
• a copolymer of styrene and butadiene prepared in emulsion having a glass transition temperature between -65 ° C and -30 ° C.
• said composition comprises cutting at least one of said polybutadienes having a rate of cis-1,4 chains greater than 90% with at least one of said copolymers styrene and butadiene prepared in solution.
• the composition comprises a cutting of at least one of the polybutadienes having a rate of cis-1,4 chains greater than 90% with at least one of the copolymers styrene and butadiene prepared as an emulsion.
• 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).
• the improvement in the wear resistance which the resin according to the invention gives to the tire casing implies a reduction in time of the compression compaction to which the tread according to the invention is subjected during rolling. and therefore a reduction over time in the rolling loss of the plasticizing oil extracted from petroleum, 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 greater than 50%.
• 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 (Si ⁇ 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.
• 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” Vol. 60, page 309, February 1938 and corresponding to standard AFNOR-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, the silicas Zeopol 8715, 8745 and 8755 from the company Huber, precipitated silicas treated such as for example the silicas "doped" with aluminum described in the aforementioned application EP-A-0735088.
• the physical state under which the reinforcing inorganic filler is present is immaterial, whether in the form of powder, microbeads, granules, or even beads.
• reinforcing inorganic filler mixtures of different reinforcing inorganic fillers, in particular highly dispersible silicas as described above.
• the reinforcing filler according to the invention advantageously comprises cutting said reinforcing inorganic filler with carbon black, the mass fraction of carbon black in said reinforcing filler being preferably chosen to be less than or equal to 30%.
• 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
• the rubber composition according to the invention also comprises, in conventional manner, 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 nature chemical 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
• 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 surface hydroxyl groups (OH) 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;
• 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.
• a reinforcing inorganic filler such as silica
• a diene elastomer such as, for example, organosilanes, in particular polysulphurized alkoxysilanes or mercaptosilanes, or alternatively polyorganosiloxanes carrying the abovementioned X and Y functions.
• - n is an integer from 2 to 8 (preferably from 2 to 5);
• R2 R2 R2 in which: the radicals R 1 , substituted or unsubstituted, identical or different from each other, represent a C 1 -C 6 alkyl, C 5 -C 18 cycloalkyl or C 6 -C 18 aryl group (preferably CC 6 alkyl groups, cyclohexyl or phenyl, in particular C 1 -C 6 alkyl groups, more particularly methyl and / or ethyl).
• the radicals R ⁇ substituted or unsubstituted, identical or different from each other, represent a CC 18 alkoxyl or C 5 -C 18 cycloalkoxyl group (preferably C ⁇ -C 8 alkoxyl or C 5 -C cycloalkoxyl groups 8 , 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.
• C 4 ) silylalkyl such as for example the bis (3-trimethoxysilylpropyl) or bis (3-triethoxysilylpropyl) polysulphides.
• bis (3-triethoxysilylpropyl) tetrasulfide, in short TESPT, of formula [(C 2 H5 ⁇ ) 3 Si (CH2) 3 2 ] 2 or bis (triethoxysilylpropyl) disulfide, in short TESPD are used in particular , of formula [ ⁇ HsO ⁇ S ⁇ CHyaSJa.
• TESPD is marketed for example by the company Degussa under the names Si266 or Si75 (in the second case, in the form of a mixture of disulfide (at 75% by weight) and polysulfides), or also 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).
• MESPT monoethoxydimethylsilylpropyl tetrasulphide
• compositions in accordance with the invention also comprise, in addition to the diene elastomer (s), said plasticizing resin, optionally said plasticizing oil, said reinforcing inorganic filler and optionally said binding agent, all or part of the other constituents and additives usually used in the compositions rubber, such as pigments, antioxidants, anti-ozonizing waxes, a crosslinking system based on either sulfur and / or peroxide and / or bismaleimides, one or more agents for covering the reinforcing inorganic filler such as alkylalkoxysilanes, polyols, amines or aids.
• 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.
• 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 tread according to the invention consists of said rubber composition of the invention, and a tire casing according to the invention comprises this tread.
• the present invention applies to all types of tire casings, which can for example be intended to equip motor vehicles or not, such as touring or competition automobiles or two-wheeled vehicles - including bicycles and light motor vehicles such as motorcycles -, industrial vehicles chosen from vans, "heavy vehicles” - ie buses, road transport equipment (trucks, tractors, trailers), off-road vehicles -, agricultural machinery or civil engineering, aircraft, other transport or handling vehicles.
• Size exclusion chromatography or SEC makes it possible to physically separate the macromolecules according to their size in the swollen state on columns filled with porous stationary phase.
• the macromolecules are separated by their hydrodynamic volume, the largest being eluted first. 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 resin 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 temperature of the 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 resin 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).
• the glass transition temperatures Tg of the elastomers and of the plasticizers were measured by means of a differential scanning calorimeter.
• Scott breaking index breaking strength (MPa) and elongation (in%) measured at 23 ° C according to standard ASTM D 412 of 1998.
• - Shore A hardness measured according to standard ASTM D 2240 of 1997.
• Hysteretic losses (PH): measured in% by rebound at 60 ° C on the sixth shock, according to the following relationship: PH (%) 100 x (Wo-W ⁇ ) / W ⁇ , with W 0 : energy supplied and W]: energy returned.
• Dynamic shear properties measured according to standard ASTM D 2231-71, approved again in 1977 (measurement as a function of the deformation carried out at 10 Hz with a peak-peak deformation of 0.15% to 50%, and measurement as a function of the temperature carried out at 10 Hz under a repetitive stress of 70 or 20N / cm 2 with a temperature sweep from -80 ° C to 100 ° C).
• Tire envelope performance measurement :
• 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 envelope tested was measured by rolling on a flywheel 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.
• 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 braking distances in "ABS" braking mode, both on dry and wet ground (polished concrete ground with 2mm height of surface water).
• 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, passing from a speed of 40 km / h at 10 km / h.
• the behavior on wet ground of each envelope was evaluated by the time taken to cover a turn of a hazy and watered road circuit which includes "macro-roughness", an assigned value of 101 corresponding to the gain of 1 second on this turn of circuit.
• the resistance of the tire casings to the separation of the crown plies was also evaluated by means of relative performance indices, compared to a reference index 100 characterizing a “control” envelope (a performance index higher than this base 100 reflecting a performance superior to that of the corresponding “witness” envelope).
• This resistance was measured by a rolling test on a steering wheel, the surface of which is provided with obstacles (bars and "polar" which come to stress the edges of the belt of the envelope made up of two working top plies), at a ambient temperature of 20 ° C, under a load of 490 daN and at a speed of 75 km / h, the internal pressure of the casing being regulated at 2.5 bar. This test is stopped when a deformation of the crown reinforcement of the envelope is detected. Each envelope was previously “steamed” (not assembled) for 4 weeks at 65 ° C.
• reaction is stopped by the introduction of 116 ml of deionized water, and 13.8 ml of a 100g / l antioxidant solution with the designation "A02246" in toluene are injected into the medium.
• the solution is then concentrated on a rotary evaporator, then the drying is finished overnight in a stave at 250 ° C. under a weak stream of depressurized nitrogen.
• compositions T and I are intended to constitute a tread for a tire envelope of the “touring” type.
• the following table contains: the formulation of each of these compositions T and I; the properties of each composition T and I in the non-crosslinked and crosslinked state and the performance of the corresponding tire casings of dimensions 175/70 R14 "MXT".
• S-SBR A copolymer of styrene and butadiene prepared in solution having a rate of 1,2 chains of 58%, a rate of styrene chains of 25%, a Mooney viscosity ML (l + 4) at 100 ° C equal to 54, an amount of oil equal to 37.5 phr and a glass transition temperature Tg of -29 ° C.
• BR A polybutadiene having a rate of cis-1,4 linkages of approximately 93%, a glass transition temperature Tg of -103 ° C and a Mooney ML viscosity (l + 4) at 100 ° C of 54.
• the Tg of composition I according to the invention under a dynamic stress of high modulus (0.7 MPa), is provided for substantially equal to the corresponding Tg of the “control” composition T.
• the difference between the Tg of the compositions T and I which were measured under a dynamic stress of reduced modulus, equal to 0.2 MPa is very close to the difference between the Tg of the said compositions T and I which have been measured under said high modulus stress.
• composition I shows that the incorporation of the resin according to the invention into composition I gives the envelopes whose treads are made of this composition I a very improved wear resistance compared to that of envelopes incorporating the “control” composition T devoid of resin, without penalizing the performance of adhesion, behavior on wet ground and rolling resistance of said composition T and while practically maintaining the mechanical properties (MA 100 and Scott breaking) of said composition T.
• This resin according to the invention also gives the envelopes incorporating it an improved endurance, insofar as it improves their resistance to the separation of the triangulation crown plies that each of these envelopes comprises in its crown reinforcement.
• composition I according to the invention comprises much less aromatic oil than the “control” composition T, which contributes to the protection of the environment by notably reducing the pollution resulting from the exudation of this oil by tires, this exudation being further minimized due to the increased wear resistance of the tires of the invention.

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• Chemical Kinetics & Catalysis (AREA)
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• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Tires In General (AREA)

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• 2003
  • 2003-07-22 AU AU2003254559A patent/AU2003254559A1/en not_active Abandoned
  • 2003-07-22 WO PCT/EP2003/007970 patent/WO2004013220A1/fr active Application Filing
  • 2003-07-22 EP EP03766252A patent/EP1527131A1/de not_active Withdrawn
  • 2003-07-22 JP JP2004525275A patent/JP2005534758A/ja active Pending
  • 2003-07-22 CN CNB038181355A patent/CN100387648C/zh not_active Expired - Lifetime
• 2005
  • 2005-01-31 US US11/045,150 patent/US7431061B2/en not_active Expired - Lifetime

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