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
  • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
  • B60C11/14—Anti-skid inserts, e.g. vulcanised into the tread band
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
  • B60C1/0016—Compositions of the tread
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K7/00—Use of ingredients characterised by shape
  • C08K7/02—Fibres or whiskers
• • 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
  • C08K7/00—Use of ingredients characterised by shape
  • C08K7/22—Expanded, porous or hollow particles
• • 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
  • C08K7/00—Use of ingredients characterised by shape
  • C08K7/22—Expanded, porous or hollow particles
  • C08K7/24—Expanded, porous or hollow particles inorganic
• • 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
  • C08K7/00—Use of ingredients characterised by shape
  • C08K7/22—Expanded, porous or hollow particles
  • C08K7/24—Expanded, porous or hollow particles inorganic
  • C08K7/26—Silicon- containing compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L7/00—Compositions of natural rubber
• • 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

Definitions

• the invention relates to rubber compositions that can be used as tire treads for vehicles, in particular "winter tires” capable of rolling 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.
• the present invention relates to a rubber composition that can be used in particular as a tread of a tire, 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 it further comprises between 2 and 50 phr of hollow microparticles of metal oxide and between 2 and 50 phr of water-soluble short fibers.
• these hollow microparticles and water-soluble fibers, protruding on the surface of the tread fulfill the claw function previously described without the disadvantage of being abrasive vis-à-vis the asphalt used as a road surface .
• all these microparticles release microcavities that act as storage volume and drain channel of the water film on the surface of the 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.
• 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 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 invention is therefore based on at least one diene elastomer, a plasticizer system, a reinforcing filler, hollow microparticles of metal oxide and water-soluble short fibers, components which are described in detail below. .
• 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, with a level of units of diene origin which is low or very low, always less than 15. % (in moles).
• 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%>(%> in moles).
• 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.
• 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 greater than 90%, butadiene-styrene copolymers 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 blending (mixing) with at most 50 phr a polybutadiene having a cis-1,4 bond ratio 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 especially in a blend with at most 50 phr of natural rubber or synthetic polyisoprene.
• Another essential feature of the rubber composition of the invention is that it 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.
• any extender oil whether aromatic or non-aromatic, any liquid plasticizer known for its plasticizing properties vis-à-vis diene elastomers, is usable.
• 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), oils paraffinic, MES (Medium Extracted Solvates) oils, 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, azelates, sebacates, glycerol and mixtures of these compounds.
• glycerol triesters preferably consisting predominantly (for more than 50%, more preferably more than 80% by weight) of an unsaturated fatty acid Ci 8 is 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 (trioleates) 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 of the invention is preferably greater than 40 phr, more preferably within a range of 50 to 100 phr.
• the compositions of 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". ".
• 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”).
• 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, vinyl- toluene, para-tert-butylstyrene, methoxystyrenes, chlorostyrenes, hydroxystyrenes, vinylmesitylene, divinylbenzene, vinylnaphthalene, any vinylaromatic monomer derived 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 i.e., liquid plasticizer plus, where appropriate, solid hydrocarbon resin
• the level of total plasticizer is preferably between 40 and 100 phr, more preferably in a range of 50 to 80 phr.
• 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 whatever its color and origin (natural or synthetic), called “white” charge, “clear” charge or even “non-black” charge as opposed to carbon black, capable of reinforcing on its own, with no other means than an intermediate coupling agent, a rubber composition intended for the tire manufacturing, in other words able to replace, in its reinforcing function, a conventional carbon black 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 those skilled in the art, in particular any precipitated or fumed silica having a BET surface and a CTAB specific surface both less than 450 m 2 / g, preferably from 30 to 400 m 2 / g, especially between 60 and 300 m 2 / g
• HDS highly dispersible precipitated silicas
• the total reinforcing filler content (carbon black and / or reinforcing inorganic filler) 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.
• an at least bifunctional coupling agent (or bonding agent) is used in a well-known manner to 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 C 1 -C 18 alkylene groups or C 6 -C 12 arylene groups, more particularly C 1 -C 10 alkylenes, especially C 1 -C 4 alkylenes, in particular propylene);
• R.1 radicals substituted or unsubstituted, identical or different, represent an alkyl group Ci-Cig, cycloalkyl C 5 -C 8 aryl or C 6 -C 8 (of Any alkyl Ci-C 6, cyclohexyl or phenyl, especially alkyl groups C 1 -C 4 alkyl, 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).
• polysulfurized silanes mention may be made more particularly of bis (3-trimethoxysilylpropyl) or bis (3-triethoxysilylpropyl) polysulfides.
• bis (3-triethoxysilylpropyl) tetrasulfide, abbreviated as TESPT, or bis (triethoxysilylpropyl) disulfide, abbreviated as TESPD is especially used.
• polysulphides in particular disulphides, trisulphides or tetrasulphides
• bis (monoalkoxyl (C 1 -C 4 ) -dialkyl (C 1 -C 4 ) silylpropyl) more particularly bis-monoethoxydimethylsilylpropyl tetrasulfide, such 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 rubber compositions of the invention have the essential characteristic of comprising between 2 and 50 phr of hollow microparticles of at least one (that is to say one or more) metal oxide, the term oxide including, of course, hydroxides .
• These microparticles may be, for example, in the form of powder, microbeads, granules, beads or any other suitable densified form. A presentation in powder form is preferred.
• microparticles is meant by definition and in general size particles (by size, we mean the largest dimension in the case of anisometric particles) micrometer, that is to say whose median size (expressed by weight) is between 1 ⁇ and 1 mm.
• the median size is between 2 ⁇ and 800 ⁇ , more preferably in a range from 5 to 200 ⁇ .
• 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 microparticles have a median size between 2 ⁇ and 500 ⁇ , more preferably still in a range from 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 level of microparticles is preferably between 5 and 40 phr, more preferably between 10 and 35 phr.
• 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 average size (or median diameter) is finally calculated in a known manner from the histogram of the particle size distribution.
• a defined quantity of sample for example 200 g
• 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 average size (or median diameter) is finally calculated in
• compositions of the invention comprise from 2 to 50 phr, preferably from 5 to 20 phr, of water-soluble short fibers.
• short fibers non-continuous fibers, the length of which is preferably greater than 1 mm and more preferably less than 30 mm, in particular in a range of 2 to 15 mm, in particular in a range of 4 to 12 mm.
• these short fibers are monofilament or multifilamentary fibers whose elementary filaments have a mean diameter (in number) which is between 5 and 50 ⁇ , preferably between 10 and 30 ⁇ , in particular between 15 and 25 ⁇ .
• water-soluble fibers are preferably chosen from the group consisting of polyvinyl alcohol fibers (PVA), cellulose fibers (for example cotton fibers, wood fibers, rayon fibers, viscose fibers), polysaccharide fibers (for example starch fibers, xanthan fibers) and mixtures of such fibers. More preferably still, the water-soluble fibers used are PVA fibers. 4.6 - Miscellaneous additives
• the rubber compositions of 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 of the invention are manufactured in suitable mixers, using two successive preparation phases according to a general procedure well known to those skilled in the art: a first phase of work or thermomechanical mixing (sometimes referred to as “non-phase” 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 phase of work or thermomechanical mixing (sometimes referred to as "non-phase” 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 between 2 and 50 phr of hollow microparticles of metal oxide and between 2 and 50 phr of water-soluble short fibers, by thermomechanically kneading the whole, in one or more times, until a maximum temperature of between 130 ° C. and 200 is reached. ° 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 may constitute all or only part of the tread according to the invention, in the case of a strip of composite type bearing formed of several rubber compositions of different formulations.
• the invention relates to the rubber and tire compositions described above both in the green (i.e., before firing) and the fired (i.e., after crosslinking or vulcanization) state.
• the reinforcing filler carbon black, silica and its agent
• the initial batch temperature of which was approximately 60 ° C. associated coupling the liquid plasticizer, hollow microparticles of aluminosilicate, water-soluble short fibers of PVA, the diene elastomer (or diene elastomer blending) as well as 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
• the mixture thus obtained is recovered, cooled and then sulfur and a sulfenamide type accelerator are incorporated on an external mixer (homo-finisher) at 30 ° C., mixing the whole (productive phase) for a suitable time (for example between 5 and 12 minutes).
• 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 ).
• a given speed for example 5 km / h
• an imposed load for example equal to 3 kg / cm 2 .
• 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 a 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 ratio Fx / Fz determines the coefficient of friction of the specimen on the ice.
• the temperature during the measurement is set at -2 ° C.
• composition C-3 according to the invention has a very clear increase (46%) of the coefficient of friction on ice, compared to the control composition Cl, while this increase does not exceed 15% on the composition C-2 (not according to the invention) certainly comprising hollow microparticles of metal oxide but devoid of water-soluble short fibers.
• compositions according to the invention offer the tires and their treads a melting ice adhesion which is greatly improved.
• PVA short fibers (“Kuralon 1239" from Kuraray).

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

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Cited By (15)

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Citations (35)

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• 2010
  • 2010-03-19 FR FR1051970A patent/FR2957602B1/fr not_active Expired - Fee Related
• 2011
  • 2011-03-09 WO PCT/EP2011/053550 patent/WO2011113731A1/fr not_active Ceased
  • 2011-03-09 JP JP2013500420A patent/JP2013522427A/ja active Pending
  • 2011-03-09 EP EP11709367A patent/EP2547726A1/fr not_active Withdrawn
  • 2011-03-09 EA EA201290932A patent/EA201290932A1/ru unknown
  • 2011-03-09 CA CA2788056A patent/CA2788056A1/fr not_active Abandoned

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