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
• • 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
• • 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
  • B60C11/0041—Tyre tread bands; Tread patterns; Anti-skid inserts comprising different tread rubber layers
  • B60C11/005—Tyre tread bands; Tread patterns; Anti-skid inserts comprising different tread rubber layers with cap and base layers
• • 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
  • B60C19/00—Tyre parts or constructions not otherwise provided for
  • B60C19/002—Noise damping elements provided in the tyre structure or attached thereto, e.g. in the tyre interior
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L21/00—Compositions of unspecified rubbers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
  • C08L9/06—Copolymers with styrene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L57/00—Compositions of unspecified polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T152/00—Resilient tires and wheels
  • Y10T152/10—Tires, resilient
  • Y10T152/10495—Pneumatic tire or inner tube
  • Y10T152/10765—Characterized by belt or breaker structure
  • Y10T152/1081—Breaker or belt characterized by the chemical composition or physical properties of elastomer or the like

Definitions

• the invention relates to tires for motor vehicles and rubber compositions used for the manufacture of such tires. It is more particularly related to the rubber compositions used in the crown ("crown") of tires with radial carcass reinforcement, to reduce the noise emitted by these tires during rolling.
• the noise emitted by a rolling tire originates, inter alia, from the vibrations of its structure consecutive to the contact of the tire with the irregularities of the roadway, also causing a generation of various acoustic waves.
• the whole thing finally comes in the form of noise, both inside and outside the vehicle.
• the amplitude of these various manifestations is dependent on the vibration modes of the tire itself but also on the nature of the coating on which the vehicle moves.
• the frequency range corresponding to the noise generated by the tires typically ranges from about 20 to about 4000 Hz.
• the acoustic waves emitted by the tire are directly propagated by air inside the vehicle, the latter acting as a filter; this is referred to as airborne transmission, which generally dominates in high frequencies
• the so-called “road noise” refers rather to the perceived overall level in the vehicle and in a frequency range up to 2000 Hz.
• the noise called “road noise” refers to the annoyance due to the resonance of the inflation cavity of the tire envelope.
• the various interactions between the tire and the road surface, the tire and the air, which will cause discomfort to the residents of the vehicle when the latter is driving on a road are relevant. floor.
• noise noise refers to the noise, the sharp squeaking that tires can do as a result of their tread rubbing during a slip, especially during low speed turns. (For example when passing through a roundabout) on pavements rendered smooth after prolonged use and aging, the specific range of frequencies concerned here corresponds to a range from about 2000 to about 10 000 Hz.
• a first object of the invention relates to a radial tire for a motor vehicle, comprising: a top having a tread provided with at least one radially outer portion intended to come into contact with the road;
• crown reinforcement or belt disposed circumferentially between the radially outer portion of the tread and the carcass reinforcement
• inner crown layer a radially inner elastomeric layer (8) called "inner crown layer", a formulation different from the formulation of the radially outer portion (3 a) of the tread, this inner crown layer being itself disposed circumferentially either between the radially outer part (3a) of the bearing (3) and the crown reinforcement (7), either between the crown reinforcement (7) and the carcass reinforcement (6), characterized in that the inner crown layer comprises a rubber composition comprising 50 to 100 phr of a copolymer based on styrene and butadiene having a Tg (glass transition temperature) greater than -4 ° C, a reinforcing filler, a plasticizing hydrocarbon resin and a crosslinking system.
• Tg glass transition temperature
• 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, trailers, off-the-road vehicles such as agricultural or civil engineering vehicles).
• 4x4 vehicles four-wheel drive
• SUV vehicles Sport Utility Vehicles
• two-wheel vehicles including motorcycles
• industrial vehicles chosen in particular from vans and "heavy goods vehicles” (ie, metro, buses, road transport vehicles such as trucks, tractors, trailers, off-the-road vehicles such as agricultural or civil engineering vehicles).
• the invention relates to the above tires both in the green (i.e., before firing) and the fired (i.e., after crosslinking or vulcanization) state.
• FIGS. 1 to 3 diagrammatically show, in radial section, examples of radial tires in accordance with FIG. 'invention.
• iene elastomer or indistinctly rubber is meant an elastomer derived at least in part (that is to say a homopolymer or a copolymer) from monomer (s) diene (s) (ie, carrier (s) two carbon-carbon double bonds, conjugated or not).
• isoprene elastomer a homopolymer or copolymer of isoprene, in other words a diene elastomer selected from the group consisting of natural rubber (NR), synthetic polyisoprenes (IR), the various copolymers of isoprene, isoprene and mixtures of these elastomers.
• NR natural rubber
• IR synthetic polyisoprenes
• 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).
• the tire of the invention therefore has the essential feature of being provided with an inner crown layer comprising a rubber composition which comprises at least 50 to 100 phr of a copolymer based on styrene and butadiene having a higher Tg. at -40 ° C, a reinforcing filler, a plasticizing hydrocarbon resin and a crosslinking system, components which will be described in detail below.
• a rubber composition which comprises at least 50 to 100 phr of a copolymer based on styrene and butadiene having a higher Tg. at -40 ° C, a reinforcing filler, a plasticizing hydrocarbon resin and a crosslinking system, components which will be described in detail below.
• the first essential characteristic of the rubber composition forming the protective elastomer underlayer is that it comprises 50 to 100 phr of a copolymer based on styrene and butadiene, that is at least one copolymer of at least a styrene monomer and at least one butadiene monomer; in other words, said copolymer based on styrene and butadiene has by definition at least units derived from styrene and units derived from butadiene.
• a second essential characteristic of the copolymer is that its Tg is greater than -40 ° C, in particular between -40 ° C and 0 ° C.
• the level of said copolymer in the protective elastomer layer is in a range of 50 to 90 phr, more preferably in a range of 60 to 85 phr.
• butadiene monomers 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-di (C 1 -C 5 alkyl) -1,3-butadienes, such as for example 2, are particularly suitable.
• styrene monomers are especially suitable styrene, methylstyrenes, para-tert-butylstyrene, methoxystyrenes, chloro styrenes.
• Said copolymer based on styrene and butadiene may have any microstructure which is a function of the polymerization conditions used, in particular the presence or absence of a modifying and / or randomizing agent and amounts of modifying and / or randomizing agent used. It can be for example block, statistical, sequenced, microsequenced, and be prepared in dispersion or in solution; it may be coupled and / or starred or functionalized with a coupling agent and / or starring or functionalization.
• the styrene-butadiene-based copolymer is selected from the group consisting of styrene-butadiene copolymers (abbreviated to SBR), styrene-butadiene-isoprene copolymers (abbreviated to SBIR) and mixtures of such copolymers.
• SBR styrene-butadiene copolymers
• SBIR styrene-butadiene-isoprene copolymers
• SBIR copolymers there may be mentioned especially those having a styrene content of between 5% and 50% by weight and more particularly 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 (mol%) in -1,2 units.
• an SBR copolymer is used.
• SBR copolymers there may be mentioned especially those having a styrene content of between 5% and 60% by weight and more particularly between 20% and 50%, a content (mol%) in -1,2 bonds of the butadiene part. between 4% and 75%, a content (mol%) of trans-1,4 bonds of between 10% and 80%.
• the Tg of the copolymer based on styrene and butadiene is greater than -35 ° C., in particular between -35 ° C. and 0 ° C., in particular greater than -30 ° C., in particular between -30 ° C. and 0 ° C (for example in a range of -25 ° C to -5 ° C).
• the preferential Tg domain may also include positive values (ie greater than 0 ° C), for example being in a range of -30 ° C to +30 ° C (especially from -25 ° C to + 25 ° C).
• Tg of the elastomers described here is measured in a conventional manner, well known to those skilled in the art, on an elastomer in the dry state (ie, without extension oil) and by DSC (for example according to ASTM D3418-1999). .
• the person skilled in the art knows how to modify the microstructure of a copolymer based on styrene and butadiene, in particular on an SBR, to increase and adjust its Tg, in particular by modifying the styrene contents in -1-bonds. 2 or in trans-1,4 bonds of the butadiene part. More preferably, an SBR (solution or emulsion) having a styrene content (mol%) which is greater than 35%, more preferably between 35% o and 60%) is used. SBR high Tg are well known to those skilled in the art, they have been used in particular in tire treads to improve some of their properties of use.
• copolymer based on styrene and butadiene above may be associated with at least a second diene elastomer, different from said copolymer (that is to say having no units derived from styrene and butadiene), said second elastomer diene being present at a weight ratio which is therefore at most equal to 50 phr (as a reminder, pce signifying parts by weight per hundred parts of elastomer, that is to say of the total of the elastomers present in the inner layer of Mountain peak).
• This second optional diene elastomer is preferably selected from the group consisting of natural rubbers (NR), synthetic polyisoprenes (IR), polybutadienes (BR), isoprene copolymers and mixtures of these elastomers.
• Such copolymers are more preferably selected from the group consisting of isoprene-butadiene copolymers (BIR) and isoprene-styrene copolymers (SIR).
• polybutadiene homopolymers and in particular those having a content (mol%) in units of 1,2,2 between 4% and 80% or those having a content (mol%) of cis-1, are particularly suitable, 4 greater than 80%>; polyisoprene homopolymers (IR); butadiene-isoprene copolymers (BIR) and in particular those having an isoprene content of between 5% and 90% by weight and a Tg of -40 ° C to -80 ° C .; isoprene-styrene copolymers (SIR) 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.
• IR polyisoprene homopolymers
• BIR butadiene-isoprene copolymers
• SIR isoprene-styrene copolymers
• the second diene elastomer is an isoprene elastomer, more preferably natural rubber or a synthetic polyisoprene of cis-1,4 type; of these synthetic polyisoprenes, polyisoprenes having a content (mol%) of cis-1,4 bonds greater than 90%, more preferably still greater than 98%, are preferably used.
• the level of second diene elastomer, in particular of isoprene elastomer, in particular of natural rubber, is in a range of 10 to 50 phr, more preferably still in a range of 15 to 40 phr.
• diene elastomers previously described could also be associated, in a minor amount, with synthetic elastomers other than dienes, or even polymers other than elastomers, for example thermoplastic polymers.
• the inner crown layer comprises any type of so-called reinforcing filler known for its ability to reinforce a rubber composition that can be used for the manufacture of pneumatic agents, for example an organic filler such as carbon black, a reinforcing inorganic filler such as silica to which is associated in a known manner a coupling agent, or a mixture of these two types of filler.
• a reinforcing filler preferably consists of nanoparticles whose average size (in mass) is less than one micrometer, generally less than 500 nm, most often between 20 and 200 nm, in particular and more preferably between 20 and 150 nm.
• the content of total reinforcing filler is greater than 20 phr, in particular between 20 and 100 phr. Above 100 phr, there is a risk of increasing the hysteresis and therefore the rolling resistance of the tires. For this reason, the total reinforcing filler content is more preferably within a range of 30 to 90 phr.
• Suitable carbon blacks are all carbon blacks, especially blacks conventionally used in tires (so-called pneumatic grade blacks).
• carbon blacks of the series 100, 200, 300, 600 or 700 (ASTM grades), for example blacks NI15, N134, N234, N326, N330, N339, N347, N375, are particularly suitable.
• the carbon blacks could for example already be incorporated into the diene elastomer, in particular isoprene in the form of a masterbatch (see for example applications 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 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, preferentially silica (SiO 2 ).
• the silica used may be any reinforcing silica known to those skilled in the art, especially any precipitated or fumed silica. having a BET surface and a CTAB specific surface 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
• 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 at least 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).
• polysulphide silanes having the following general formula (I) are not suitable for the following definition:
• x is an integer of 2 to 8 (preferably 2 to 5);
• the symbols A which are identical or different, represent a divalent hydrocarbon group (preferably an alkylene Ci-Cig or an arylene group C 6 -C 2, more particularly alkylene Ci-Cio, in particular C 1 -C 4 , especially propylene);
• the radicals R 1 which may be substituted or unsubstituted, which are identical to or different from one another, represent a Ci-C18 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 radicals R 2 substituted or unsubstituted, which are identical to or different from one another, represent a C 1 -C 8 alkoxyl or C 5 -C 8 cycloalkoxyl group (preferably a group chosen from C 1 -C 6 alkoxyls and C 5 cycloalkoxyls); -C 8 , more preferably still a group selected from alkoxy C 1 -C 4 , in particular methoxyl and ethoxyl).
• silane polysulfides are more particularly the bis (mono, trisulfide or tetrasulfide) of bis (alkoxyl (Ci-C 4) alkyl (Ci-C 4) silyl alkyl (Ci-C 4 )), such as polysulfides of bis (3-trimethoxysilylpropyl) or bis (3-triethoxysilylpropyl).
• bis (3-triethoxysilylpropyl) tetrasulfide, abbreviated TESPT of formula [(C 2 H 5 O) 3 Si (CH 2 ) 3 S 2 ] 2 or bis (triethoxysilylpropyl) disulphide is especially used.
• TESPD abbreviated TESPD, of formula [(C 2 H 5 O) 3 Si (CH 2 ) 3 S] 2 .
• polysulfides in particular disulfides, trisulphides or tetrasulfides
• bis-monoethoxydimethylsilylpropyl tetrasulfide as described in the aforementioned patent application WO 02/083782 (or US Pat. No. 7,217,751).
• silanes carrying at least one thiol function (-SH) (called mercaptosilanes) and / or of at least one blocked thiol function, as described for example in patents or patent applications US 6,849,754, WO 99/09036, WO 2006/023815, WO 2007/098080.
• the content of coupling agent is preferably between 2 and 15 phr, more preferably between 3 and 12 phr.
• the inner layer of crown has another essential feature of comprising a hydrocarbon plasticizing resin.
• a hydrocarbon plasticizing resin is hereby reserved, by definition known to those skilled in the art, to a compound that is solid at room temperature (23 ° C), as opposed to a liquid plasticizer such as an oil.
• Hydrocarbon resins are polymers well known to those skilled in the art, essentially based on carbon and hydrogen, which can be used in particular as plasticizers or tackifying agents in polymer matrices. 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, cycloaliphatic or aromatic, of the aliphatic / aromatic type, that is to say based on aliphatic and / or aromatic monomers, hydrogenated or otherwise.
• Tg is preferably greater than 0 ° C., especially greater than 20 ° C. (most often between 30 ° C. and 95 ° C.).
• these hydrocarbon resins can also be described as thermoplastic resins in that they soften by heating and can thus be molded. They can also be defined by a point or softening point, the temperature at which the product, for example in the form of powder, agglutinates; this datum tends to replace the melting point, which is rather poorly defined, of resins in general.
• the softening temperature of a hydrocarbon resin is generally about 50 to 60 ° C higher than its Tg value.
• the softening temperature of the resin is preferably greater than 40 ° C (in particular between 40 ° C and 140 ° C), more preferably greater than 50 ° C (in particular between 50 ° C). C and 135 ° C).
• the hydrocarbon resin has at least one, more preferably all of the following characteristics: a Tg greater than 25 ° C;
• a softening point greater than 50 ° C. (in particular between 50 ° C. and
• Mn number-average molar mass
• Ip polymolecularity index
• this hydrocarbon resin has at least one, more preferably all of the following characteristics: a Tg between 25 ° C and 100 ° C (especially between 30 ° C and 90 ° C); a softening point greater than 60 ° C., in particular between 60 ° C. and
• hydrocarbon resins examples include those selected from the group consisting of homopolymer or copolymer resins of cyclopentadiene (abbreviated as CPD) or dicyclopentadiene (abbreviated as DCPD) terpene homopolymer or copolymer resins, terpene phenol homopolymer or copolymer resins, homopolymer or C5 cut copolymer resins, homopolymer or C9 cut copolymer resins, homopolymer or copolymer resins, and the like. alpha-methyl-styrene and mixtures of these resins.
• CPD cyclopentadiene
• DCPD dicyclopentadiene
• copolymer resins examples include those selected from the group consisting of (D) CPD / vinylaromatic copolymer resins, (D) CPD / terpene copolymer resins, (D) copolymer resins CPD / C5 cut, (D) CPD / C5 cut copolymer resins, (D) CPD / C9 cut copolymer resins, terpene / vinylaromatic copolymer resins, terpene / phenol copolymer resins, copolymer resins C5 / vinylaromatic, and mixtures of these resins.
• pene here combines in a known manner the alpha-pinene, beta-pinene and limonene monomers; preferentially, a limonene monomer, a compound presenting with known manner in the form of three possible isomers: L-limonene (laevorotatory enantiomer), D-limonene (dextrorotatory enantiomer), or the dipentene, racemic enantiomers dextrorotatory and levorotatory.
• L-limonene laevorotatory enantiomer
• D-limonene diextrorotatory enantiomer
• dipentene racemic enantiomers dextrorotatory and levorotatory.
• Suitable monomeric monomers are, for example, styrene, alpha-methylstyrene, ortho-methylstyrene, meta-methylstyrene, para-methylstyrene, vinyl-toluene, para-tert-butylstyrene, methoxystyrenes, chlorostyrenes, hydroxystyrenes, vinylmesitylene, divinylbenzene, vinylnaphthalene, any monomer vmylaromatic resulting from a C 9 cut (or more generally from a C 8 cut to
• the resins selected from the group consisting of homopolymer resins (D) CPD, copolymer resins (D) CPD / styrene, polylimonene resins, limonene / styrene copolymer resins, resins of limonene / D copolymer (CPD), C5 / styrene cut copolymer resins, C5 / C9 cut copolymer resins, and mixtures of these resins.
• D homopolymer resins
• D copolymer resins
• D copolymer resins
• polylimonene resins limonene / styrene copolymer resins
• resins of limonene / D copolymer (CPD) resins of limonene / D copolymer
• C5 / styrene cut copolymer resins C5 / C9 cut copolymer resins
• 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”). All glass transition temperature (“Tg”) values are measured in a known manner by Differential Scanning Calorimetry (DSC) according to ASTM D3418 (1999).
• SEC steric exclusion chromatography
• the level of hydrocarbon resin in the inner crown layer is preferably between 5 and 60 phr, especially between 5 and 50 phr, more preferably still within a range of 10 to 40 phr.
• the 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 5 phr, that of the primary accelerator is preferably between 0.5 and 8 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-mercaptobenzofhiazyl 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-mercaptobenzofhiazyl disulfide
• CBS N-cyclohexyl-2-benzothiazyl sulfenamide
• DCBS N-dicyclohexyl-2-benzothiazyl sulfenamide
• the inner crown layer may also comprise all or part of the usual additives normally used in tire rubber compositions, such as, for example, protective agents such as chemical antioxidants, anti-oxidants, plasticizers or lubricating oils. extension, that these are of aromatic or non-aromatic nature, especially very low or non-aromatic oils, for example of the naphthenic or paraffmic type, high or preferably low viscosity, MES or TDAE oils, agents facilitating the implementation (processability) of the compositions in the green state, tackifying resins, reinforcing resins (such as resorcinol or bismaleimide), acceptors or methylene donors such as for example hexamethylenetetramine or hexamethoxymethylmelamine.
• protective agents such as chemical antioxidants, anti-oxidants, plasticizers or lubricating oils.
• protective agents such as chemical antioxidants, anti-oxidants, plasticizers or lubricating oils.
• these are of aromatic or non-aromatic nature, especially
• the inner crown layers may also contain coupling enhancers when a coupling agent is used, inorganic filler recovery agents when an inorganic filler is used, or more generally, blending agents.
• these agents are for example hydroxysilanes or hydrolysable silanes such as alkyl-alkoxysilanes, polyols, polyethers, amines, hydroxylated or hydrolysable polyorganosiloxanes.
• the rubber compositions forming the inner crown layer are manufactured in suitable mixers, for example 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 qualified of "non-productive" phase) at a 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 described as a "productive" phase) at a lower temperature, typically less than 120 ° C., for example between 60 ° C. and 100 ° C., a finishing phase during which the crosslinking or vulcanization system is incorporated.
• a first thermomechanical working or mixing phase sometimes qualified of "non-productive" phase
• a second phase of mechanical work sometimes described as a "productive” phase
• a finishing phase during which the crosslinking or vulcanization system is incorporated.
• a method that can be used for the manufacture of such rubber compositions comprises, for example, and preferably the following steps: incorporating in a mixer, 50 to 100 phr of the styrene-butadiene-based copolymer, the reinforcing filler and the plasticizing hydrocarbon resin, into thermomechanically kneading the whole, in one or more times, until reaching 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 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 an inner crown layer, for example as part "base" of a tread structure cap-base.
• 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 inner crown layer has, in the vulcanized state (ie, after firing), a secant modulus in extension E10 which is less than 30 MPa, more preferably between 2 and 25 MPa, in particular between 5 and 20 MPa.
• the "secant modulus in extension” (denoted E10) is the tensile modulus measured in second elongation (ie, after a cycle of accommodation) at 10% elongation (according to ASTM D412-1998, specimen "C”).
• modulus being the secant modulus "true” that is to say, brought back to the actual section of the specimen (normal temperature and humidity conditions according to ASTM D 1349-1999).
• the rubber composition described above is therefore used, in the tire of the invention, as an inner crown layer disposed circumferentially inside the crown of the tire, either between firstly the most radially outer portion of its tire strip. rolling, that is to say the portion intended to come into contact with the road during driving, and secondly the crown reinforcement or belt, or between this belt and the carcass reinforcement.
• inner top layer is meant any rubber portion of the tire crown which does not extend to the outside of the tire, which is not in contact with the air or inflation gas, in other words which is therefore located inside the internal structure of the crown of the tire.
• this inner crown layer is disposed: either in the tread itself, but in this case under the portion (that is to say radially inwardly with respect to this portion) of the tread which is intended to come into contact with the road during the rolling of the tire, throughout the lifetime of the latter;
• This elastomeric protective layer is preferably between 0.1 and 2 mm, especially in a range of 0.2 to 1.5 mm.
• Figures 1 to 3 show in radial section, very schematically (especially without respecting a specific scale), three preferred examples of pneumatic tires for motor vehicle with radial carcass reinforcement, according to the invention.
• FIG. 1 illustrates a first possible embodiment of the invention, according to which the inner crown layer (8) is integrated with the tread (3) itself, but arranged under the portion (3 a) of the tread which is intended to come into contact with the road when driving, to form what is commonly called a sub-layer of a tread.
• the tread is also commonly known to those skilled in the art of tread with a "cap-base” structure, the word “cap” designating the carved portion of the tread intended to come into contact with the road and the term “base” designating the non-carved portion of the tread, of different formulation, which is in turn not intended to come into contact with the road.
• the tire (1) schematized comprises an apex (2) comprising a tread (3) (for simplicity, with a very simple sculpture), the radially outer portion (3 a) of which is intended to be contact of the road, two non-extensible beads (4) in which is anchored a carcass reinforcement (6).
• the top (2), joined to said beads (4) by two sides (5), is known per se reinforced by a crown reinforcement or "belt" (7) at least partly metallic and radially external to the carcass reinforcement (6), constituted for example by at least two superposed cross plies reinforced by metal cables.
• the carcass reinforcement (6) is here anchored in each bead (4) by winding around two rods (4a, 4b), the upturn (6a, 6b) of this armature (6) being for example arranged outwardly tire (1) which is shown here mounted on its rim (9).
• the carcass reinforcement (6) consists of at least one ply reinforced by radial textile cords, that is to say that these cords are arranged substantially parallel to each other and extend from a bead to the other so as to form an angle of between 80 ° and 90 ° with the median circumferential plane (plane perpendicular to the axis of rotation of the tire which is located halfway between the two beads 4 and passes through the middle of the crown frame 7).
• this tire (1) further comprises, in known manner, a layer (10) of rubber or inner elastomer (commonly called “inner liner” or “inner liner”) which defines the radially inner face of the tire and which is intended for protecting the carcass ply from the diffusion of air from the interior space to the tire.
• a layer (10) of rubber or inner elastomer commonly called “inner liner” or “inner liner”
• inner liner commonly called “inner liner” or “inner liner”
• the inner crown layer (8) is external to the tread (ie, distinct from the tread), this time arranged, always in the top ( 2), below the tread (ie, radially inwardly from the tread) and above the tread (ie, radially outwardly from the tread), in other words between the tread (3) and the belt (7).
• FIG. 3 illustrates another possible embodiment of the invention, according to which the inner crown layer described above is disposed between the belt (7) and the carcass reinforcement (6) of the tire.
• the inner layer of crown thanks to its improved sound barrier properties, is able to contribute to reducing the noise emitted both inside and outside the vehicles while driving their tires; in particular, it makes it possible to significantly reduce the squeal noises emitted by these tires.

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• 2010
  • 2010-05-27 FR FR1054097A patent/FR2960544B1/fr not_active Expired - Fee Related
• 2011
  • 2011-05-17 US US13/699,850 patent/US20130153108A1/en not_active Abandoned
  • 2011-05-17 WO PCT/EP2011/057923 patent/WO2011147712A1/fr active Application Filing
  • 2011-05-17 JP JP2013511609A patent/JP2013528238A/ja not_active Ceased
  • 2011-05-17 EP EP11724384.0A patent/EP2576684A1/fr not_active Withdrawn

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