Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
  • B60C1/0016—Compositions of the tread
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
• • 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
  • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
  • C08K3/20—Oxides; Hydroxides
  • C08K3/22—Oxides; Hydroxides of metals
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2207/00—Properties characterising the ingredient of the composition
  • C08L2207/32—Properties characterising the ingredient of the composition containing low molecular weight liquid component
  • C08L2207/324—Liquid component is low molecular weight polymer

Definitions

• the invention relates to rubber compositions used as treads of tires for vehicles, in particular tires “winter” able to roll on floors covered with ice or ice without being provided with nails (also called “studless” tires).
• treads of winter tires which are specifically adapted for running under so-called "melting ice” conditions encountered in a temperature range typically between -5 ° C and 0 ° C. It is recalled that, in such a field, the pressure of the tires at the passage of a vehicle causes a superficial melting of the ice which is covered with a thin film of water detrimental to the adhesion of these tires.
• Such powders solubilize more or less in contact with snow or melted ice, which allows on the one hand the creation on the surface of the tread of porosities likely to improve the attachment of the tread on the ground and on the other hand the creation of throats acting as evacuation channels of the liquid film created between the pneumatic and soil.
• water-soluble powders include, for example, the use of cellulose powder, PVA (polyvinyl alcohol) or starch, or powders of guar gum or xanthan gum (see for example, patent application JP 3-159803, JP 2002-211203, EP 940,435, WO 2008/080750, WO 2008/080751).
• the solubility at very low temperature and in a very short time of the powder used is an essential factor for the proper functioning of the tread. If the powder is not soluble in the conditions of use of the tire, the aforementioned functions (creation of microporosities and water discharge channels) are not met and the adhesion is not improved.
• Another known drawback of these solutions is that they can strongly penalize the reinforcement of the rubber compositions (and therefore their resistance to wear) or their hysteresis (and therefore their rolling resistance).
• the Applicants have discovered a rubber composition capable of generating an effective surface microroughness by means of specific microparticles, and which makes it possible to greatly improve the ice adhesion of the treads and tires comprising them, under conditions of melting ice, without penalizing the strengthening and hysteresis properties.
• the present invention relates to a tire whose tread comprises a rubber composition comprising at least one diene elastomer, more than 30 phr of a liquid plasticizer, and between 50 and 150 phr of a reinforcing filler, characterized in that that said composition further comprises 35 to 50 phr of hollow microparticles of at least one metal oxide having a median size by weight of between 2 and 500 ⁇ .
• these hollow microparticles which are protruding on the surface of the tread, fulfill the claw function described above without the disadvantage of being highly abrasive vis-à-vis the asphalt used as a road surface.
• said microparticles create microcavities which act as storage volume and drainage channel of the water film on the surface. ice ; under these conditions, the contact between the surface of the tread and the ice is no longer lubricated and the coefficient of friction is thus improved.
• the tires of the invention are particularly intended to equip tourism-type motor vehicles, including 4x4 vehicles (four-wheel drive) and SUV vehicles ("Sport Utility Vehicles"), two-wheel vehicles (including motorcycles) as industrial vehicles chosen in particular from vans and "heavy goods vehicles” (ie, metro, buses, road transport vehicles such as trucks, tractors).
• 4x4 vehicles four-wheel drive
• SUV vehicles Sport Utility Vehicles
• two-wheel vehicles including motorcycles
• industrial vehicles chosen in particular from vans
• "heavy goods vehicles” ie, metro, buses, road transport vehicles such as trucks, tractors.
• treads and rubber compositions constitutive of these treads are characterized, before and after cooking, as indicated below.
• the measurements are carried out at 150 ° C. with an oscillating chamber rheometer according to DIN 53529 - Part 3 (June 1983).
• the evolution of the rheometric torque as a function of time describes the evolution of the stiffening of the composition as a result of the vulcanization reaction.
• the measurements are processed according to DIN 53529 - Part 2 (March 1983): Ti is the induction time, that is to say the time required for the beginning of the vulcanization reaction; T a (for example T 90 ) is the time required to achieve a cc% conversion, i.e., cc% (eg 90%) of the difference between the minimum and maximum torque.
• T a for example T 90
• cc% eg 90%
• Dynamic properties are measured on a viscoanalyzer (Metravib VA4000) according to ASTM D5992-96.
• the response of a sample of vulcanized composition (cylindrical specimen of 4 mm thickness and 400 mm 2 section), subjected to a sinusoidal stress in alternating simple shear, at the frequency of 10 Hz, at a temperature of 0, is recorded. ° C.
• a strain amplitude sweep of 0.1% to 50%> (forward cycle) is performed, followed by 50%> to 1% (return cycle).
• any range of values designated by the expression “between a and b” represents the range of values greater than “a” and less than “b” (i.e., terminals a and b excluded). while that any range of values designated by the term “from a to b” means the range of values from “a” to "b” (i.e. including the strict limits a and b).
• the rubber composition of the tread according to the invention is therefore based on at least one diene elastomer, a plasticizer system, a reinforcing filler and specific hollow microparticles, components which are described in detail hereinafter.
• elastomer or rubber, the two terms being synonymous
• dienes monomers carrying two double bonds carbon - carbon, conjugated or not
• the diene elastomers can be classified in known manner into two categories: those known as “essentially unsaturated” and those known as “essentially saturated”.
• Butyl rubbers such as, for example, copolymers of dienes and alpha-olefins of the EPDM type, fall into the category of essentially saturated diene elastomers having a diene origin ratio which is low or very low, always less than 15. % (mole%).
• essentially unsaturated diene elastomer is understood to mean a diene elastomer derived at least in part from conjugated diene monomers having a proportion of units or units of diene origin (conjugated dienes) which is greater than 15% (mol%). ).
• 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%.
• At least one diene elastomer of the highly unsaturated type in particular a diene elastomer chosen from the group consisting of natural rubber (NR), synthetic polyisoprenes (IR), polybutadienes (BR) and butadiene copolymers, copolymers of isoprene and mixtures of these elastomers.
• a diene elastomer chosen from the group consisting of natural rubber (NR), synthetic polyisoprenes (IR), polybutadienes (BR) and butadiene copolymers, copolymers of isoprene and mixtures of these elastomers.
• Such copolymers are more preferably selected from the group consisting of butadiene-styrene copolymers (SBR), isoprene-butadiene copolymers (BIR), isoprene-styrene copolymers (SIR), isoprene-copolymers of butadiene-styrene (SBIR) and mixtures of such copolymers.
• SBR butadiene-styrene copolymers
• BIR isoprene-butadiene copolymers
• SIR isoprene-styrene copolymers
• SBIR isoprene-copolymers of butadiene-styrene
• 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.
• a coupling with carbon black there may be mentioned for example functional groups comprising a C-Sn bond or amino functional groups such as benzophenone for example; for coupling to a reinforcing inorganic filler such as silica, mention may be made, for example, of silanol or polysiloxane functional groups having a silanol end (as described, for example, in US Pat. No.
• alkoxysilane groups as described, for example, in US 5,977,238), carboxylic groups (as described, for example, in US 6,815,473 or US 2006/0089445) or polyether groups (as described for example in US 6,503,973).
• elastomers such as SBR, BR, NR or IR of the epoxidized type.
• Polybutadienes and in particular those having a 1,2-unit content of between 4% and 80%, or those having a cis-1,4 content of greater than 80%, polyisoprenes and copolymers of butadiene- styrene and in particular those having a styrene content of between 5% and 50% by weight and more particularly between 20% and 40%, a 1,2-butadiene content of the butadiene part of between 4% and 65%. %, a trans-1,4-linkage content of between 20% and 80%, butadiene-isoprene copolymers and in particular those having an isoprene content of between 5% and 90% by weight and a glass transition temperature.
• Tg "Tg" - measured according to ASTM D3418-82) from -40 ° C to -80 ° C, the isoprene-styrene copolymers and in particular those having a styrene content of between 5% and 50% by weight and a Tg between -25 ° C and -50 ° C.
• butadiene-styrene-isoprene copolymers are especially suitable those having a styrene content of between 5% and 50% by weight and more particularly of between 10% and 40%, an isoprene content of between 15% and 60%.
• the diene elastomer is chosen from the group consisting of natural rubber, synthetic polyisoprenes and polybutadienes having a cis-1,4 bond ratio of greater than 90%, copolymers of butadiene-styrene and mixtures of these elastomers.
• the rubber composition comprises 50 to 100 phr of natural rubber or synthetic polyisoprene, said natural rubber or synthetic polyisoprene which can be used in particular in cutting (mixture) with not more than 50 phr of a polybutadiene having a cis-1,4 bond ratio of greater than 90%.
• the rubber composition comprises 50 to 100 phr of a polybutadiene having a cis-1,4 bond ratio greater than 90%, said polybutadiene being able to be used in particular in a blend with at most 50 pce of natural rubber or synthetic polyisoprene.
• diene elastomers of the treads according to the invention could be associated, in a minor amount, synthetic elastomers other than diene, or even polymers other than elastomers, for example thermoplastic polymers.
• the rubber composition according to the invention comprises at least 30 phr of a liquid plasticizer (at 20 ° C.) whose function is to soften the matrix by diluting the elastomer and the reinforcing filler; its Tg is by definition less than -20 ° C, preferably less than -40 ° C.
• a liquid plasticizer at 20 ° C.
• Tg is by definition less than -20 ° C, preferably less than -40 ° C.
• these plasticizers or these oils are liquids (that is to say, as a reminder, substances having the capacity to eventually take on the shape of their container) , in contrast to, in particular, hydrocarbon plasticizing resins which are inherently solid at room temperature.
• liquid plasticizers selected from the group consisting of naphthenic oils (low or high viscosity, including hydrogenated or not), paraffinic oils, MES oils (Medium Extracted Solvates), Treated Distillate Aromatic Extracts (TDAE) oils, mineral oils, vegetable oils, ethers plasticizers, ester plasticizers, phosphate plasticizers, sulphonate plasticizers and mixtures of these compounds.
• phosphate plasticizers for example, mention may be made of those containing from 12 to 30 carbon atoms, for example trioctyl phosphate.
• ester plasticizers mention may be made in particular of compounds selected from the group consisting of trimellitates, pyromellitates, phthalates, 1,2-cyclohexane dicarboxylates, adipates, azela- lates, sebacates, tri-esters, glycerol and mixtures of these compounds.
• glycerol triesters preferably consisting mainly (for more than 50%>, more preferably for more than 80% by weight) of a unsaturated fatty acid Ci 8, that is to say selected from the group consisting of oleic acid, linoleic acid, linolenic acid and mixtures of these acids. More preferably, whether of synthetic or natural origin (for example vegetable oils of sunflower or rapeseed), the fatty acid used is more than 50% by weight, more preferably still more than 80% by weight. % by weight of oleic acid.
• Such high oleic acid triesters are well known and have been described, for example, in application WO 02/088238, as plasticizers in tire treads.
• the level of liquid plasticizer in the composition according to the invention is preferably greater than 40 phr, more preferably within a range of 50 to 100 phr.
• compositions according to the invention may also comprise, as solid plasticizer (at 20 ° C.), a hydrocarbon resin having a Tg greater than + 20 ° C., preferably greater than + 30 ° C. C, as described for example in applications WO 2005/087859, WO 2006/061064 and WO 2007/017060.
• Hydrocarbon resins are polymers that are well known to those skilled in the art, essentially based on carbon and hydrogen, and therefore inherently miscible in diene (s) elastomer compositions when they are further qualified as “plasticisers”. ". They have been described, for example, in the book “Hydrocarbon Resins” by R. Mildenberg, M. Zander and G. Collin (New York, VCH, 1997, ISBN 3-527-28617-9), chapter 5 of which is devoted their applications, in particular pneumatic rubber (5.5 “Rubber Tires and Mechanical Goods”). They may be aliphatic, aromatic or aliphatic / aromatic type that is to say based on aliphatic and / or aromatic monomers. They may be natural or synthetic, whether or not based on petroleum (if so, also known as petroleum resins). They are preferably exclusively hydrocarbon-based, that is to say they contain only carbon and hydrogen atoms.
• the plasticizing hydrocarbon resin has at least one, more preferably all, of the following characteristics: a Tg greater than 20 ° C (more preferably between 40 and 100 ° C);
• Mn a number-average molecular weight (Mn) of between 400 and 2000 g / mol (more preferentially between 500 and 1500 g / mol);
• the Tg is measured in a known manner by DSC (Differential Scanning Calorimetry), according to the ASTM D3418 (1999) standard.
• the macrostructure (Mw, Mn and Ip) of the hydrocarbon resin is determined by steric exclusion chromatography (SEC): solvent tetrahydrofuran; temperature 35 ° C; concentration 1 g / 1; flow rate 1 ml / min; filtered solution on 0.45 ⁇ porosity filter before injection; Moore calibration with polystyrene standards; set of 3 "WATERS” columns in series (“STYRAGEL” HR4E, HR1 and HR0.5); differential refractometer detection (“WATERS 2410") and its associated operating software (“WATERS EMPOWER”).
• SEC steric exclusion chromatography
• the plasticizing hydrocarbon resin is chosen from the group consisting of cyclopentadiene homopolymer or copolymer resins (abbreviated to CPD), dicyclopentadiene homopolymer or copolymer resins (abbreviated to DCPD), homopolymer or terpene copolymer resins, C5 homopolymer or copolymer resins, C9 homopolymer or copolymer resins, and mixtures of these resins.
• CPD cyclopentadiene homopolymer or copolymer resins
• DCPD dicyclopentadiene homopolymer or copolymer resins
• C5 homopolymer or copolymer resins C9 homopolymer or copolymer resins
• copolymer resins are more preferably used those selected from the group consisting of (D) CPD / vinylaromatic copolymer resins, (D) CPD / terpene copolymer resins, copolymer resins (D) CPD / C5 cut, (D) CPD / C9 cut copolymer resins, terpene / vinylaromatic copolymer resins, terpene / phenol copolymer resins, C5 / vinylaromatic cut copolymer resins, C9 / 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-, meta-, para-methylstyrene, vinyltoluene, para-tert-butylstyrene, methoxystyrenes, chlorostyrenes, hydroxystyrenes, vinylmesitylene, and the like. , divinylbenzene, vinylnaphthalene, any vinylaromatic monomer from a C 9 cut (or more generally from a C 8 to C 10 cut).
• the vinyl-aromatic compound is styrene or a vinylaromatic monomer derived from a C 9 cut (or more generally from a C 8 to C 10 cut).
• the vinylaromatic compound is the minor monomer, expressed as a mole fraction, in the copolymer under consideration.
• the content of hydrocarbon resin is preferably between 3 and 60 phr, more preferably between 3 and 40 phr, especially between 5 and 30 phr.
• the level of total plasticizer ie, liquid plasticizer plus, if appropriate, solid hydrocarbon resin
• 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, or a reinforcing inorganic filler such as silica to which is associated in a known manner a coupling agent.
• Such a reinforcing filler typically consists of nanoparticles whose average size (in mass) is less than 500 nm, most often between 20 and 200 nm, in particular and preferably between 20 and 150 nm.
• Suitable carbon blacks are all carbon blacks, especially blacks conventionally used in tires or treads of tires (so-called pneumatic grade blacks).
• the reinforcing carbon blacks of the 100, 200 or 300 series for example blacks NI15, N134, N234, N326, N330, N339, N347, N375, will be mentioned more particularly.
• 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 mention may be made of functionalized polyvinyl organic fillers as described in applications WO-A-2006/069792 and WO-A-2006/069793, WO-A-2008/003434. and WO-A-2008/003435.
• Reinforcing inorganic filler means any inorganic or mineral filler, irrespective of its color and origin (natural or synthetic), also called “white” filler, “clear” filler or even “non-black” filler. "As opposed to carbon black, capable of reinforcing on its own, with no other means than an intermediate coupling agent, a rubber composition for the manufacture of tires, in other words able to replace, in its function of reinforcement, 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
• Suitable reinforcing inorganic fillers are in particular siliceous type mineral fillers, in particular silica (SiO 2) , or aluminous type, in particular alumina (Al 2 O 3 ),
• the silica used may be any reinforcing silica known from the person skilled in the art, in particular any precipitated or fumed silica having a BET surface, and that a CTAB specific surface area both less than 450 m 2 / g, preferably 30 to 400 m 2 / g, especially between 60 and 300 m 2 / g.
• HDS highly dispersible precipitated silicas
• reinforcing aluminas examples include “Baikalox” A 125 or CRI 25 aluminas from Baikowski, “APA-100RDX” from Condea, “Aluminoxid C” from Degussa or “AKP-G015" from Sumitomo Chemicals.
• the total reinforcing filler content is between 60 and 120 phr, in particular between 70 and 100 phr.
• the filler comprises silica, carbon black or a mixture of carbon black and silica.
• the reinforcing filler comprises predominantly carbon black; in such a case, the carbon black is present at a level preferably greater than 60 phr, associated or not with a reinforcing inorganic filler such as silica in a minority amount.
• the reinforcing filler comprises an inorganic filler, in particular silica, as a majority; in such a case, the inorganic filler, in particular silica, is present at a rate preferably greater than 70 phr, associated or not with carbon black in a minor amount; 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).
• the majority use of a reinforcing inorganic filler such as silica is also advantageous from the point of view of adhesion. on wet or snowy ground.
• the reinforcing filler comprises a blend of carbon black and reinforcing inorganic filler such as silica in similar amounts; in such a case, the level of inorganic filler, in particular silica, and the level of carbon black are preferably each between 25 and 75 phr, more particularly each between 30 and 50 phr.
• a well-known at least bifunctional coupling agent (or bonding agent) is well known for ensure a sufficient chemical and / or physical connection between the inorganic filler (surface of its particles) and the diene elastomer.
• organosilanes or bifunctional polyorganosiloxanes are used.
• polysulfide silanes, called “symmetrical” or “asymmetrical” silanes according to their particular structure, are used, as described for example in the applications WO03 / 002648 (or US 2005/016651) and WO03 / 002649 (or US 2005/016650).
• x is an integer of 2 to 8 (preferably 2 to 5);
• A is a divalent hydrocarbon radical (preferably alkylene groups
• C 18 or C 6 -C 12 arylene groups more particularly C 1 -C 10 alkylenes, especially C 1 -C 4 alkylenes, in particular propylene);
• R2 R2 in which:
• the radicals R.1 which may be substituted or unsubstituted, which are identical to or different from one another, represent a Ci-Cs alkyl, C 5 -C 8 cycloalkyl or C 6 -C 18 aryl group (preferably C 1 -C 8 alkyl groups); -C 6 , cyclohexyl or phenyl, especially C 1 -C 4 alkyl groups, more particularly methyl and / or ethyl).
• the R radicals substituted or unsubstituted, identical or different, represent an alkoxyl group Ci-Cig cycloalkoxy or C 5 -C 8 (preferably a group selected from Ci-Cg alkoxyls and C 5 cycloalkoxyls -C 8 , more preferably still a group selected from C 1 -C 4 alkoxyls, in particular methoxyl and ethoxyl).
• polysulphide silanes examples include polysulfides of bis (3-trimethoxysilylpropyl) or of bis (3-triethoxysilylpropyl).
• polysulfides of bis (3-trimethoxysilylpropyl) or of bis (3-triethoxysilylpropyl examples include bis (3-triethoxysilylpropyl) tetrasulfide, abbreviated as TESPT, or bis (triethoxysilylpropyl) disulfide, abbreviated as TESPD, is especially used.
• polysulfides in particular disulphides, trisulphides or tetrasulfides
• monoalkoxyl C 1 -C 4 ) -dialkyl (C 1 -C 4 ) silylpropyl
• bis-monoethoxydimethylsilylpropyl tetrasulfide as described in patent application WO 02/083782 (or US 2004/132880).
• the content of coupling agent is preferably between 2 and 12 phr, more preferably between 3 and 8 phr.
• the equivalent filler of the reinforcing inorganic filler described in this paragraph it would be possible to use a reinforcing filler of another nature, in particular an organic filler, since this reinforcing filler would be covered with a filler.
• inorganic layer such as silica, or would comprise on its surface functional sites, especially hydroxyl, requiring the use of a coupling agent to establish the bond between the filler and the elastomer.
• the rubber composition according to the invention has the essential feature of comprising 35 to 50 phr of hollow microparticles (or microspheres) of at least one metal oxide, the term oxide including, of course, hydroxides; these microparticles have a median size by weight of between 2 and 500 ⁇ .
• microparticles is meant by definition and generally micrometric size particles, that is to say whose average size or median size (both expressed by weight) are between 1 ⁇ and 1 mm.
• the intended technical effect namely the creation of a suitable micro-roughness
• the rubber composition is used as a tread: in addition to a possible loss of aesthetics (particles too visible on the surface of the tread) and a risk of loosening, during rolling, relatively large tread elements it was found that the melting ice adhesion performance could be degraded.
• the hollow microparticles have a median size (by weight) within a range of 5 to 200 ⁇ . This area of particularly preferred size seems to correspond to an optimized compromise between on the one hand the desired surface roughness and on the other hand a good contact between the rubber composition and the ice.
• the metal of the metal oxide is selected from the group consisting of aluminum, silicon, zirconium, transition metals and mixtures of such metals.
• transition metal is meant more particularly the metals of the fourth period ranging from scandium to zinc, preferably titanium and zinc.
• Aluminum, silicon, titanium, zirconium and zinc are even more preferable.
• the metal oxide is chosen from the group consisting of aluminum oxides and / or hydroxides, oxides and / or hydroxides of silicon, oxides and / or hydroxides of aluminum and silicon, and mixtures of such oxides and / or hydroxides. More preferably still, the metal oxide used is an aluminosilicate.
• various known methods are applicable, for example by laser diffraction (see, for example, ISO-8130-13 or JIS standard K5600-9-3).
• the operation consists in sieving a defined quantity of sample (for example 200 g) on a vibrating table for 30 min with different sieve diameters (for example, according to a progression reason equal to 1.26, with meshes of 1000, 800, 630, 500, 400, ... 100, 80, 63 ⁇ ); the refusals collected on each sieve are weighed on a precision scale; we deduce the% of refusal for each mesh diameter with respect to the total weight of product; the median (or median diameter) or mean (or mean diameter) size is finally calculated in a known manner from the histogram of the particle size distribution. 5.5 - Miscellaneous additives
• the rubber compositions according to the invention also comprise all or part of the usual additives usually used in elastomer compositions intended for the manufacture of tire treads, in particular for winter tires, such as, for example, protective agents such as waxes.
• protective agents such as waxes.
• compositions may also contain coupling activators when a coupling agent is used, inorganic filler recovery agents or, more generally, processing aid agents that are capable 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 ability to implement in the green state;
• these agents are for example hydrolysable silanes such as alkyl-alkoxysilanes, polyols, polyethers, amines, hydroxylated or hydrolysable polyorganosiloxanes.
• the rubber compositions according to the invention are manufactured in appropriate mixers, using two successive preparation phases according to a general procedure well known to those skilled in the art: a first thermomechanical working or mixing phase (sometimes referred to as a "no" phase). -productive ”) at high temperature, up to a maximum temperature of between 130 ° C and 200 ° C, preferably between 145 ° C and 185 ° C, followed by a second phase of mechanical work (sometimes called phase" Producer ”) at a lower temperature, typically below 120 ° C, for example between 60 ° C and 100 ° C, finishing phase during which is incorporated the crosslinking system or vulcanization.
• a first thermomechanical working or mixing phase (sometimes referred to as a "no" phase).
• -productive ) at high temperature, up to a maximum temperature of between 130 ° C and 200 ° C, preferably between 145 ° C and 185 ° C
• a second phase of mechanical work sometimes called phase” Producer ”
• a method that can be used for the manufacture of such compositions comprises, for example, and preferably the following steps: incorporating into the diene elastomer, in a mixer, more than 30 phr of a liquid plasticizer, between 50 and 150 phr of a reinforcing filler , 35 to 50 phr of hollow microparticles of a metal oxide having a median weight of between 2 and 500 ⁇ , by thermomechanically kneading the whole, in one or more times, until a maximum temperature of between 130 ° C. and 200 ° C;
• the first (non-productive) phase is carried out in a single thermomechanical step during which all the necessary constituents, the possible coating agents, are introduced into a suitable mixer such as a conventional internal mixer. or other complementary additives and other additives, with the exception of the crosslinking system.
• a suitable mixer such as a conventional internal mixer. or other complementary additives and other additives, with the exception of the crosslinking system.
• the low temperature crosslinking system is then incorporated, generally in an external mixer such as a roll mill; the whole is then mixed (productive phase) for a few minutes, for example between 5 and 15 min.
• the actual crosslinking system is preferably based on sulfur and a primary vulcanization accelerator, in particular a sulfenamide type accelerator.
• a primary vulcanization accelerator in particular a sulfenamide type accelerator.
• various known secondary accelerators or vulcanization activators such as zinc oxide, stearic acid, guanidine derivatives (especially diphenylguanidine), etc.
• the sulfur content is preferably between 0.5 and 3.0 phr, that of the primary accelerator is preferably between 0.5 and 5.0 phr.
• accelerator primary or secondary
• any compound capable of acting as an accelerator of vulcanization of diene elastomers in the presence of sulfur in particular thiazole-type accelerators and their derivatives, accelerators of thiuram type, zinc dithiocarbamates.
• These accelerators are more preferably selected from the group consisting of 2-mercaptobenzothiazyl disulfide (abbreviated "MBTS”), N-cyclohexyl-2-benzothiazyl sulfenamide (abbreviated “CBS”), N, N-dicyclohexyl-2-benzothiazyl sulfenamide (“DCBS”), N-tert-butyl-2-benzothiazylsulfenamide (“TBBS”), N-tert-butyl-2-benzothiazylsulfenimide (“TBSI”), zinc dibenzyldithiocarbamate (“ZBEC”) and mixtures thereof. these compounds.
• MBTS 2-mercaptobenzothiazyl disulfide
• CBS N-cyclohexyl-2-benzothiazyl sulfenamide
• DCBS N-dicyclohexyl-2-benzothiazyl sulfenamide
• 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 that can be used directly as a tread of a tire. winter.
• 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, the system of vulcanization adopted and the kinetics of vulcanization of the composition under consideration.
• the rubber compositions according to the invention previously described may constitute only part of the tread according to the invention, at least for the portion (therefore carved) of the tread intended to come into contact with the road during the rolling of the tire.
• the invention relates to the tires previously described both in the green state (ie, before firing) and in the fired state (ie, after crosslinking or vulcanization).
• the reinforcing filler carbon black, silica and its agent
• the initial batch temperature of which was approximately 60 ° C. associated coupling the liquid plasticizer
• the hollow microparticles of metal oxide the diene elastomer (or diene elastomer cutting)
• the various other ingredients with the exception of the vulcanization system; the mixer is thus filled to about 70% (% by volume).
• 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.
• Tables 1 and 2 give the formulation of the two compositions (Table 1 - rate of the various products expressed in phr), their properties before and after curing (30 min at 150 ° C.); the vulcanization system is sulfur and sulfenamide.
• the two compositions are then subjected to a laboratory test consisting in measuring their coefficient of friction on ice.
• the principle is based on a rubber composition slider sliding at a given speed (for example 5 km / h) on an ice track with an imposed load (for example equal to 3 kg / cm 2 ).
• the surface of the test pad Prior to the test, the surface of the test pad is lapped by planing to a thickness of 0.5 mm, followed by a series of repeated sliding friction on real dry soil (asphalt) under the said imposed load (for example 3 kg / cm 2 ).
• the forces generated in the direction of advance (Fx) of the pad and perpendicular to the advance (Fz) are measured.
• the Fx Fz ratio determines the coefficient of friction of the specimen on the ice.
• the temperature during the measurement is set at -2 ° C.
• compositions according to the invention offer the tires and their treads a melting ice adhesion which is significantly improved.
• Zerosil 1115MP silica from Rhodia, type “HDS” (BET and CTAB: about 120 m 7 g);

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• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Compositions Of Macromolecular Compounds (AREA)
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• 2009
  • 2009-12-18 FR FR0959168A patent/FR2955584B1/fr not_active Expired - Fee Related
• 2010
  • 2010-12-14 CA CA2784412A patent/CA2784412A1/fr not_active Abandoned
  • 2010-12-14 WO PCT/EP2010/069621 patent/WO2011073186A1/fr not_active Ceased
  • 2010-12-14 EA EA201290524A patent/EA201290524A1/ru unknown
  • 2010-12-14 JP JP2012543681A patent/JP5778171B2/ja not_active Expired - Fee Related
  • 2010-12-14 EP EP10790785A patent/EP2512825A1/fr not_active Withdrawn

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