Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L3/00—Compositions of starch, amylose or amylopectin or of their derivatives or degradation products
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
  • B60C1/0016—Compositions of the tread
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/02—Elements
  • C08K3/04—Carbon
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/02—Elements
  • C08K3/06—Sulfur
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/04—Oxygen-containing compounds
  • C08K5/09—Carboxylic acids; Metal salts thereof; Anhydrides thereof
• • 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
  • C08K5/16—Nitrogen-containing compounds
  • C08K5/17—Amines; Quaternary ammonium compounds
  • C08K5/18—Amines; Quaternary ammonium compounds with aromatically bound amino groups
• • 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
  • C08K5/16—Nitrogen-containing compounds
  • C08K5/29—Compounds containing one or more carbon-to-nitrogen double bonds
  • C08K5/31—Guanidine; Derivatives thereof
• • 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
  • C08K5/36—Sulfur-, selenium-, or tellurium-containing compounds
  • C08K5/45—Heterocyclic compounds having sulfur in the ring
  • C08K5/46—Heterocyclic compounds having sulfur in the ring with oxygen or nitrogen in the ring
  • C08K5/47—Thiazoles
• • 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
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L91/00—Compositions of oils, fats or waxes; Compositions of derivatives thereof
• • 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
  • C08K2003/2296—Oxides; Hydroxides of metals of zinc
• • 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
  • C08K3/01—Use of inorganic substances as compounding ingredients characterized by their specific function
  • C08K3/013—Fillers, pigments or reinforcing additives
• • 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
  • 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
• • 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
  • C08K5/54—Silicon-containing compounds
  • C08K5/548—Silicon-containing compounds containing sulfur
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L3/00—Compositions of starch, amylose or amylopectin or of their derivatives or degradation products
  • C08L3/02—Starch; Degradation products thereof, e.g. dextrin

Definitions

• the invention relates to rubber compositions useful in particular as treads of "winter tires” capable of rolling on floors covered with ice or ice without being provided with nails (also called “studless” tires).
• treads for winter tires 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 in fact 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.
• solid particles of high hardness such as, for example, silicon carbide (see, for example, US Pat. No. 3,878,147), some of which are flush with the surface of the tread. as it wears, and thus come into contact with the ice.
• Such particles able to act finally as micro-nails on hard ice, thanks to a well known "claw" effect, remain relatively aggressive vis-à-vis the ground; they are not well adapted to driving conditions on melting ice.
• 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.
• P10-2060 PCT 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 new rubber composition, capable of generating an effective surface microroughness by means of microparticles which are neither of high hardness nor water-soluble, and which makes it possible to improve the ice adhesion of bearing and tires comprising them, under melting ice conditions, without significantly penalizing the reinforcing and hysteresis properties.
• a first subject of the invention relates to a rubber composition that can be used as tread of a winter tire, comprising at least one diene elastomer, more than 30 phr of a liquid plasticizer, and between 50 and 150 phr of a tire. reinforcing filler, said composition being characterized in that it further comprises between 5 and 40 phr of wheat semolina microparticles.
• these wheat microparticles protruding on the surface of the tread, fulfill the claw function previously described without the disadvantage of being abrasive.
• the invention also relates to the use of such a rubber composition for the manufacture of tire treads winter, that they are intended for new tires as retreading tires used.
• the invention also relates to these treads and these tires themselves when they comprise a rubber composition according to the invention.
• the tires of the invention are particularly intended for equipping tourism-type motor vehicles, including 4x4 vehicles (four-wheel drive) and SUV vehicles ("Sport Utility Vehicles"), two-wheeled vehicles (especially motorcycles) as vehicles.
• industrial vehicles chosen in particular from vans and "heavy goods vehicles” (ie, metros, buses, road transport vehicles (trucks, tractors, trailers)), off-the-road vehicles such as agricultural or civil engineering vehicles.
• treads and rubber compositions constituting these treads are characterized, before and after cooking, as indicated below.
• the Mooney plasticity measurement is carried out according to the following principle: the composition in the uncured state (ie, before firing) is molded in a cylindrical chamber heated to 100 ° C. After one minute of preheating, the rotor rotates within the 2 rpm test piece and the useful torque is measured to maintain this movement after 4 minutes of rotation.
• the measurements are carried out at 130 ° C., in accordance with the French standard NF T 43-005.
• the evolution of the consistency index as a function of time makes it possible to determine the toasting time of the rubber compositions, evaluated according to the above-mentioned standard by the parameter T5 (case of a large rotor), expressed in minutes, and defined as being the time required to obtain an increase in the consistometric index (expressed in MU) of 5 units above the minimum value measured for this index.
• 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 ⁇ (for example T 90 ) is the time necessary to reach a conversion of ⁇ %, that is to say a% (for example 90%) of the difference between the minimum and maximum couples.
• the Shore A hardness of the compositions after curing is assessed according to ASTM D 2240-86.
• 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) and then 50% to 1% (return cycle) are performed.
• the results exploited are the loss factor tan ( ⁇ ); for the return cycle, the maximum value of tan ( ⁇ ) observed (denoted tan ( ⁇ ) max ) is given between the values at 0.15% and at 50% deformation (Payne effect).
• the tires are mounted on a motor vehicle (“Toyota Camry") equipped with anti-lock braking system (ABS) and traction control system (TCS system for Traction Control System).
• ABS anti-lock braking system
• TCS system for Traction Control System traction control system
• the rubber composition of the invention is based on at least one diene elastomer, a plasticizer system, a reinforcing filler and wheat semolina microparticles, components which are described in detail below.
• any range of values designated by the expression "between a and b" represents the range of values from more than a to less than b (i.e. terminals a and b excluded) while any range of values designated by the term “from a to b” means the range from a to b (i.e., including the strict limits a and b).
• elastomer or "diene” rubber it is recalled that must be understood an elastomer derived at least in part (i.e. a homopolymer or a copolymer) of monomers dienes (monomers bearing two carbon-carbon double bonds, 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”.
• essentially saturated diene elastomers having a rate of diene origin units that 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 level of units or units of diene origin.
• P10-2060 PCT It is preferred to use at least one diene elastomer of the highly unsaturated type, in particular a diene elastomer chosen from the group consisting of polybutadienes (BR), synthetic polyisoprenes (IR), natural rubber (NR), butadiene copolymers, isoprene copolymers (other than HR) and mixtures of these elastomers.
• a diene elastomer chosen from the group consisting of polybutadienes (BR), synthetic polyisoprenes (IR), natural rubber (NR), butadiene copolymers, isoprene copolymers (other than HR) 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, sequence, microsequential, and be prepared in dispersion or in solution; they can be coupled and / or star or functionalized with a coupling agent and / or starring or functionalization.
• a coupling agent for example, there may be mentioned for example functional groups comprising a C-Sn bond or amino functional groups such as benzophenone for example;
• 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 content of trans-1,4 bonds 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" - measured according to ASTM D3418-82) of -40 ° C.
• Tg glass transition temperature
• the isoprene-styrene copolymers and in particular those having a styrene content of between 5% and 50% by weight and a Tg of 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%. by weight and more particularly between 20% and 50%, a butadiene content of between 5% and 50% by weight and more particularly between 20% and 40%, a content of -1,2 units of the butadiene part between 4% and 85%, a trans-1,4 units content of the butadiene part of between 6% and 80%, a -1,2 plus -3,4 units content of the part
• 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 diene elastomer used is predominantly, that is to say for more than 50 phr (as a reminder, "phr” meaning parts by weight per hundred parts of elastomer), natural rubber (NR) or synthetic polyisoprene (IR). More preferably, said natural rubber or synthetic polyisoprene is then used in blending with a polybutadiene (BR) having a cis-1,4 bond ratio which is preferably greater than 90%.
• phr meaning parts by weight per hundred parts of elastomer
• NR natural rubber
• IR synthetic polyisoprene
• BR polybutadiene
• the diene elastomer used is predominantly, that is to say for more than 50 phr, a polybutadiene (BR) having a cis-1,4 bond ratio greater than 90% . More preferably, said polybutadiene is then used in a blend with natural rubber or synthetic polyisoprene.
• BR polybutadiene
• the diene elastomer used is a binary (mixing) blend of NR (or IR) and BR, or a ternary blend of NR (or IR), BR and SBR.
• the composition comprises between 25 and 75 phr of NR (or IR) and between 75 and 25 phr of BR, to which may be associated or not a third elastomer (ternary cutting) at a lower rate. at 30 phr, especially less than 20 phr.
• This third elastomer is preferably an SBR elastomer, in particular an SBR solution (called "SSBR").
• the composition comprises from 35 to 65 phr of NR (or IR) and from 65 to 35 phr of BR.
• the BR used is preferably a BR having a cis-1,4 bond ratio greater than 90%, more preferably greater than 95%.
• 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.
• Another essential feature of the rubber composition of the invention is that it comprises at least 30 phr of a liquid plasticizing agent (at 23 ° C.) whose function is to
• P10-2060 PCT 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; liquid plasticizers selected from the group consisting of naphthenic oils, paraffinic oils, MES oils, TDAE oils, ester plasticizers and mixtures of these compounds are particularly suitable.
• ester plasticizers preferably consisting predominantly (for more than 50%, more preferably for more than 80% by weight) of a Cis unsaturated fatty acid, ie in 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 of the invention is preferably greater than 40 phr, more preferably within a range of 50 to 100 phr.
• compositions of the invention may also comprise, as solid plasticizer (at 23 ° 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 well known to those skilled in the art, which are therefore miscible in nature in diene (s) elastomer compositions when they are further qualified as “plasticizers". They have been described, for example, in the book entitled
• the plasticizing hydrocarbon resin has at least one, more preferably all, of the following characteristics:
• Tg greater than 20 ° C .
• Mn number-average molecular mass
• Ip polymolecularity index
• Tg is measured in a known manner by Differential Scanning Calorimetry (DSC) according to ASTM D3418 (1999).
• the macrostructure (Mw, Mn and Ip) of the hydrocarbon resin is determined by steric exclusion chromatography (SEC): solvent tetrahydrofuran; temperature 35 0 C; concentration 1 g / 1; flow rate 1 ml / min; filtered solution on porosity filter
• the plasticizing hydrocarbon resin is chosen from the group consisting of homopolymer or copolymer resins of cyclopentadiene (abbreviated as CPD) or dicyclopentadiene (abbreviated as DCPD), terpene homopolymer or copolymer resins, C5 homopolymer or copolymer resins, and mixtures of these resins.
• CPD cyclopentadiene
• DCPD dicyclopentadiene
• terpene homopolymer or copolymer resins C5 homopolymer or copolymer resins, and mixtures of these resins.
• copolymer resins are preferably used those selected from the group consisting of copolymer resins (D) CPD / vinylaromatic, copolymer resins (D) CPD / terpene, copolymer resins (D) CPD / cut C5, terpene / vinylaromatic copolymer resins, C5 / vinylaromatic cut copolymer resins, and mixtures of these resins.
• pene here combines in a known manner the alpha-pinene, beta-pinene and limonene monomers; preferably, a limonene monomer is used which is 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, phenol, alpha-methylstyrene, ortho-, meta-, para-methylstyrene, vinyl-toluene, para-tert-butylstyrene, methoxystyrenes, chlorostyrenes, vinylmesitylene, and the like. , divinylbenzene, vinylnaphthalene, any vinylaromatic monomer from a Cg cut (or more generally a Cs to Cio cut).
• the vinyl aromatic compound is styrene or a vinyl aromatic monomer from a C 9 fraction (or more generally a C $ cutting -C 10).
• 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 5 and 60 phr, especially between 5 and 40 phr, more preferably between 10 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 of the HAF, ISAF, SAF type conventionally used in tire treads.
• the reinforcing carbon blacks of the 100, 200 or 300 series for example Nl 15, N134, N234, N326, N330, N339, N347 or 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
• Reinforcing inorganic filler means any inorganic or mineral filler, irrespective of its color and origin (natural or synthetic), also called “white” filler or sometimes “clear” filler 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 manufacture of tires, 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, mineral fillers of the siliceous type, in particular silica (SiC 2), or aluminous type, in particular alumina (Al 2 O 3).
• the silica used may be any reinforcing silica known to those skilled in the art, in particular any precipitated or fumed silica having a BET surface and a CTAB specific surface both less than 450 m 2 / g, preferably from 30 to 400 m 2 / g, especially between 60 and 300 m 2 / g.
• HDS highly dispersible precipitated silicas
• the Ultrasil 7000 and Ultrasil 7005 silicas from Degussa mention may be made of, for example, the Ultrasil 7000 and Ultrasil 7005 silicas from Degussa, the Zeosil 1165MP, 1135MP and 1115MP silicas from Rhodia, the Hi-SiI silica EZ150G from the PPG company, the Zeopol 8715, 8745 and 8755 silicas of the Huber Company.
• reinforcing aluminas examples include “Baikalox”"A125” or “CR125” aluminums from Baikowski, “APA-100RDX” from Condea, “Aluminoxid C” from Degussa or “AKP-G015" from Sumitomo Chemicals .
• 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 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 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 8 alkylene groups or C 6 -C n arylene groups, more particularly C 1 -C 10 alkylenes, especially C 1 -C 4 alkylenes, in particular propylene);
• Z is one of the following formulas:
• R radicals substituted or unsubstituted, identical or different, represent an alkyl group Ci-Cj 8 cycloalkyl, C 5 -cj 8 -aryl or C O -C I 8 (preferably groups C 1 -C 6 alkyl, cyclohexyl or phenyl, especially C 1 -C 4 alkyl groups, more particularly methyl and / or ethyl).
• R radicals substituted or unsubstituted, identical or different, represent an alkoxy group of C J -C J OR 8 cycloalkoxy, C 5 -cj 8 (preferably a group selected from alkoxyl Cj-C 8 and C 5 -C 8 cycloalkoxyls, 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 disulfide.
• the content of coupling agent is preferably between 4 and 12 phr, more preferably between 3 and 8 phr.
• the rubber compositions of the invention have the essential characteristic of comprising between 5 and 40 phr of wheat semolina microparticles.
• microparticles is meant by definition of micrometric size particles, that is to say greater than one micrometer; preferably, their average size and their median size (both expressed in weight) are between 1 .mu.m and 1 mm. Preferably, the median size is between 50 microns 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 microparticles have a median size of between 100 ⁇ m and 800 ⁇ m, more preferably still in a range of 300 to 600 ⁇ m. 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 35 phr, more preferably between 10 and 30 phr.
• microparticles of wheat intended for human consumption are used by milling or grinding processes in which the sound and the seed are largely eliminated.
• semolina or flours that could be described as "coarse”
• crushed wheat grains crushed coarsely, of any shape and generally having relatively salient angles.
• 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 size (or median diameter) is finally calculated in a known manner from the histogram of the particle size distribution.
• 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. anti-ozone, chemical antiozonants, antioxidants, reinforcing resins, acceptors (for example novolac phenolic resin) or methylene donors (for example HMT or H3M), a
• P10-2060 PCT crosslinking system based on either sulfur, or sulfur and / or peroxide donors and / or bismaleimides, vulcanization accelerators, vulcanization activators.
• 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 a high temperature, up to a maximum temperature of between 130 ° C. and 200 ° C., preferably between 145 ° C. and
• a second phase of mechanical work (sometimes referred to as a "productive" phase) at a lower temperature, typically less than 120 ° C., for example between
• a method that can be used for the manufacture of such compositions comprises, for example, and preferably the following steps:
• a liquid plasticizer between 50 and 150 phr of a reinforcing filler, between 5 and 40 phr of wheat semolina microparticles, by thermomechanically mixing the whole, in one or more times, until a maximum temperature of between 130 ° C. and 200 ° C. is reached; cool the assembly to a temperature below 100 0 C; then incorporate a crosslinking system; knead everything to a maximum temperature below 120 0 C; - Extrude or calender the rubber composition thus obtained, especially in the form of a tire tread.
• the first (non-productive) phase is carried out in a single thermomechanical step in the course of which all the necessary constituents, the possible caustic agents, are introduced into a suitable mixer such as a conventional internal mixer.
• 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 0 C and 200 0 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 can constitute all or only part of the tread according to the invention, in the case of a composite type tread formed of several rubber compositions of different formulations.
• P 10-2060 PCT The invention relates to the rubber compositions and treads previously described both in the green state (Le., Before firing) and in the fired state (ie, after crosslinking or vulcanization).
• the reinforcing filler for example a reinforcing inorganic filler such as silica and its agent
• the initial vessel temperature of which is approximately 60 ° C. associated coupling the liquid plasticizer
• the wheat semolina microparticles 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
• 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 thus obtained are then calendered either in the form of plates (thickness of 2 to 3 mm) or thin sheets of rubber for the measurement of their physical or mechanical properties, or extruded in the form of tire treads winter vehicle tourism.
• Tables 1 and 2 give the formulation of the three compositions (Table 1 - rate of the different products expressed in phr, that is to say parts by weight per hundred parts of elastomer (total elastomer)), their properties before and after baking (30 min at 150 ° C); the vulcanization system is sulfur and sulfenamide.
• the processability in the green state is unexpectedly slightly improved for the compositions of the invention; the rheometric properties (cooking) are not significantly modified, the roasting safety (T5) being even increased by 4 min; - After cooking, Shore hardness and modules in extension remain constant, which is favorable to the mechanical behavior of the tread, therefore the road behavior of the tire; the reduction of the properties at break, in particular of the stress at break, if it can be described as expected, nevertheless remains in a non-prohibitive range for the skilled person; finally, the hysteresis is not increased, which is the recognized indicator of undegraded rolling resistance.
• Previously tested compositions CI, C-2 and C-3 are then used as tire treads for winter tires with a radial carcass, respectively denoted PI (control tires), P-2 and P-3 (tires according to the invention). ), 205/65 Rl 5 conventionally manufactured and identical in all respects, except for the rubber compositions constitutive of their tread.
• All tires are mounted at the front and rear of a motor vehicle, under nominal inflation pressure, and are run on a circuit (about 2000 km), on dry ground, for running-in and beginning of wear.
• the P-3 tires whose tread includes wheat semolina microparticles whose median size is in the particularly preferred range of 300 to 600 ⁇ m, are clearly those displaying the best combined performance of adhesion and acceleration on ice.
• wheat semolina (median particle size: about 200 ⁇ m);

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• 2007
  • 2007-12-27 FR FR0760390A patent/FR2925913B1/fr not_active Expired - Fee Related
• 2008
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  • 2008-12-15 WO PCT/EP2008/010650 patent/WO2009083125A1/fr not_active Ceased
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