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
  • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
  • B60C9/02—Carcasses
  • B60C9/04—Carcasses the reinforcing cords of each carcass ply arranged in a substantially parallel relationship
  • B60C9/08—Carcasses the reinforcing cords of each carcass ply arranged in a substantially parallel relationship the cords extend transversely from bead to bead, i.e. radial ply
• • 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
  • B60C1/0008—Compositions of the inner liner
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/02—Elements
  • C08K3/04—Carbon
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/34—Silicon-containing compounds
  • C08K3/36—Silica
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • 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
  • 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
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/18—Homopolymers or copolymers of hydrocarbons having four or more carbon atoms
  • C08L23/20—Homopolymers or copolymers of hydrocarbons having four or more carbon atoms having four to nine carbon atoms
  • C08L23/22—Copolymers of isobutene; Butyl rubber ; Homo- or copolymers of other iso-olefins
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/26—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers modified by chemical after-treatment

Definitions

• the present invention relates to a rubber composition for the manufacture of tires and in particular for the manufacture of an air-impermeable inner layer, commonly called "tire inner liner”.
• Tubeless tires in fact have a low air permeability inner surface in order to avoid deflation of the tire and to protect the inner sensitive zones of the latter against oxygen and water inflows, such as webs containing metal cables sensitive to oxidation, this protection to improve the endurance of the tire.
• Today such protection of the inner surface of the tires is achieved by inner gums consisting of elastomeric compositions based on butyl rubber.
• reinforcing fillers such as carbon black
• P10-2002 / SC JP 2004143366 A discloses an inner tire rubber composition, based on butyl rubber and comprising carbon black, which also comprises graphite dispersed in the elastomeric matrix. The addition of this graphite to improve the impermeability to gases. However, the fact of adding an additional charge is detrimental to the processability of the mixture.
• oils are known for their ability to improve the processability but it is also known that they can affect the sealing.
• the combination of graphite and low-mass polyisobutylene oil makes it possible to improve the sealability, even with respect to a composition which includes only graphite, and, on the other hand, that this composition permits also to iso-sealing with respect to the graphite-resin solution (French application of the aforementioned applicant) to lower the hysteresis of the mixture and therefore to lower the rolling resistance of a tire whose inner liner would be made from of this composition.
• the subject of the invention is a novel composition, in particular for an inner tire liner, having improved imperviousness properties compared with the aforementioned solutions, as well as improved rolling resistance, without degrading the mechanical properties of processability and flexural strength.
• the invention relates to a rubber composition based on at least one major elastomer selected from the group consisting of butyl rubbers, essentially unsaturated diene elastomers, essentially saturated diene elastomers and mixtures of these elastomers, and a reinforcing filler characterized in that the composition also comprises graphite and a functionalized or non-functionalized polyisobutylene oil having a molecular mass of between 200 g / mol and 40,000 g / mol, preferably between 500 g / mol and 35,000 g / mol and even more preferably 1000 g / mol and 30,000 g / mol, present in a proportion of between 2 and 50 phr.
• the majority elastomer is constituted by a butyl rubber, and more particularly by a copolymer of isobutene and isoprene or a brominated or chlorinated polyisobutylene.
• the majority elastomer is a diene elastomer, and advantageously a substantially unsaturated or essentially saturated diene elastomer.
• the majority elastomer represents 100% of the elastomers of the composition.
• the composition comprises one or more other elastomers chosen from the group consisting of butyl rubbers, essentially unsaturated diene elastomers, essentially saturated diene elastomers and mixtures of these elastomers.
• the graphite is in a lamellar form.
• the gaphite may be a natural, expandable, expanded or synthetic graphite, it may also be a blend of natural graphite and / or expandable natural graphite and / or expanded graphite and / or synthetic graphite.
• the invention also relates to a pneumatic object having a rubber composition based on at least one major elastomer chosen from the group consisting of butyl rubbers, essentially unsaturated diene elastomers, essentially saturated diene elastomers and mixtures of these elastomers.
• the composition also comprises graphite and a functionalized or non-functionalized polyisobutylene oil, having a molecular mass of between 200 g / mol and 40,000 g / mol, preferably between 500 g / mol and 35,000 g / mol and still more preferably 1000 g / mol and 30 000 g / mol, present in a proportion - A - between 2 and 50 phr, and also relates to a tire comprising such a rubber composition.
• a functionalized or non-functionalized polyisobutylene oil having a molecular mass of between 200 g / mol and 40,000 g / mol, preferably between 500 g / mol and 35,000 g / mol and still more preferably 1000 g / mol and 30 000 g / mol, present in a proportion - A - between 2 and 50 phr, and also relates to a tire comprising such a rubber composition.
• the invention finally relates to a process for preparing a composition based on at least one major elastomer chosen from the group consisting of butyl rubbers, essentially unsaturated diene elastomers, essentially saturated diene elastomers and mixtures of these elastomers, and a reinforcing filler, characterized in that the composition also comprises graphite and a functionalized or non-functionalized polyisobutylene oil, said process comprising the following steps:
• the rubber compositions are characterized, before and after firing, 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 dynamic properties ⁇ G * and tan ( ⁇ ) max are measured on a viscoanalyzer (Metravib V A4000), according to the ASTM D 5992 - 96 standard.
• the response of a sample of vulcanized composition (cylindrical test piece 2 mm in diameter) is recorded. thickness and 78.5 mm2 section), subjected to sinusoidal stress in alternating simple shear, at a frequency of 10 Hz, under normal temperature conditions according to ASTM D 1349 - 99.
• a strain amplitude sweep is carried out peak to peak of 0.1 to 50% (forward cycle), then 50% to 0.1% (return cycle).
• the results used are the complex dynamic shear modulus (G *) and the loss factor, tan ( ⁇ ).
• the maximum value of tan ( ⁇ ) observed (tan ( ⁇ ) max) as well as the complex modulus difference ( ⁇ G *) between the values at 0.15 and 50% of deformation (Payne effect).
• the permeability values are measured using a MOCON OXTRAN 2/60 permeability tester at 40 ° C. Samples baked in the form of discs of a determined thickness (approximately 0.8 to 1 mm) are mounted on the apparatus and sealed with vacuum grease. One side of the disc is kept under 10 psi of nitrogen while the other side is kept under 10 psi of oxygen. The increase in oxygen concentration is monitored by using a "Coulox" oxygen sensor on the face maintained under nitrogen. The oxygen concentration is noted on the face maintained under nitrogen to reach a constant value, used to determine the permeability to oxygen.
• the rubber composition according to the invention based on at least one major elastomer (that is to say for more than 50 phr), chosen from the group consisting of butyl rubbers, essentially unsaturated diene elastomers and elastomers. essentially saturated dienes and mixtures of these elastomers, and a reinforcing filler is characterized in that it also comprises graphite and a polyisobutylene oil functionalized or not, having a molecular mass of between 200 g / mol and 40 000 g / mol, present in a proportion of between 2 and 50 phr.
• major elastomer that is to say for more than 50 phr
• the composition For its use as the inner liner of a tire, the composition comprises, as elastomer, an elastomer chosen from the group consisting of butyl rubbers.
• an elastomer chosen from the group consisting of butyl rubbers.
• the improved sealing and hysteresis properties of the compositions in accordance with the invention make it possible to also recommend their use at other locations of the tire (tread, sidewall, .7) which mainly use diene elastomers essentially. unsaturated or not and / or cuts thereof.
• composition according to the invention for a tubeless tire sealing inner liner contains at least one butyl rubber, used alone, in a blend with one or more other butyl rubber or diene elastomers.
• butyl rubber is meant a homopolymer of poly (iso-butylene) or a copolymer of polyisobutylene with isoprene (in this case this butyl rubber is part of the diene elastomers), as well as halogenated derivatives, in particular generally brominated or chlorinated, of these poly (isobutylene) homopolymers and copolymers of poly (isobutylene) and isoprene.
• butyl rubber that are particularly suitable for carrying out the invention are: copolymers of isobutylene and isoprene (HR), bromo-butyl rubbers such as bromoisobutylene-isoprene copolymer (BIIR), chlorobutyl rubbers such as chloroisbutylene-isoprene copolymer (CIIR) and isobutylene rubbers.
• BIIR bromoisobutylene-isoprene copolymer
• chlorobutyl rubbers such as chloroisbutylene-isoprene copolymer
• isobutylene rubbers also referred to as "butyl rubber” copolymers of isobutylene and styrene derivatives such as copolymers of isobutylene and brominated methylstyrene (BIMS) including the elastomer named EXXPRO include marketed by Exxon.
• elastomer or “diene” rubber it is to be understood in a known manner (one or more elastomers) is understood to come from at least a part (ie a homopolymer or a copolymer) of monomers dienes (monomers carrying two carbon-carbon double bonds , conjugated or not).
• diene elastomers can be classified into two categories: "essentially unsaturated” or "essentially saturated”.
• essentially unsaturated is generally 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 (conjugated dienes) which is greater than 15% (mol%).
• conjugated diene monomers having a level of units or units of diene origin (conjugated dienes) which is greater than 15% (mol%).
• 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%.
• diene elastomers such as certain butyl rubbers or copolymers of dienes and alpha-olefins of the EPDM type may be described as "essentially saturated" diene elastomers (level of units of diene origin which is weak or very weak, always less than 15%).
• iene elastomer is used more particularly, whatever the category above, which can be used in the compositions according to the invention:
• the present invention is preferably implemented with essentially saturated elastomers, in particular of type (d) above.
• conjugated dienes 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-di (C 1 -C 5) alkyl-1,3-butadienes, such as for example 2 3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-methyl-3-ethyl-1,3-butadiene, 2-methyl-3-isopropyl-1, 3-butadiene, aryl-1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene.
• alkyl-1,3-butadienes such as for example 2 3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-methyl-3-ethyl-1,3-butadiene, 2-methyl-3-isopropyl-1, 3-butadiene, aryl-1,3-butadiene, 1,3-pentadiene, 2,4-hexa
• Suitable vinylaromatic compounds are, for example, styrene, ortho-, meta-, para-methylstyrene, the "vinyl-toluene" commercial mixture, para-tertiobutylstyrene, methoxystyrenes, chlorostyrenes, vinylmesitylene, divinylbenzene, vinylnaphthalene.
• the copolymers may contain between 99% and 20% by weight of diene units and between 1% and 80% by weight of vinylaromatic units.
• the elastomers 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 the amounts of modifying and / or randomizing agent used.
• 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.
• alkoxysilane groups such as as described for example in FR 2,765,882 or US 5,977,238), carboxylic groups (as described for example in WO 01/92402 or US 6,815,473, WO 2004/096865 or US 2006/0089445) or groups polyethers (as described for example in EP 1 127 909 or US Pat. No. 6,503,973).
• functionalized elastomers mention may also be made of elastomers (such as SBR, BR, NR or IR) of the epoxidized type.
• Tg glass transition temperature
• styrene content of between 5% and 60% by weight and more particularly between 20% and 50%; content (mol%) in -1,2 bonds of the butadiene part of between 4% and 75%, a content (mol%) of trans-1,4 bonds of between 10% and 80%, butadiene-isoprene copolymers and in particular those having an isoprene content of between 5% and 90% by weight and a Tg of -40 ° C. to -80 ° C., the isoprene-styrene copolymers and especially 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 including between 10% and 40%, an isoprene content of between 15% and 60% by weight and more particularly between 20% and 50%, a content of in butadiene of between 5% and 50% by weight and more particularly between 20% and 40%, a content (mol%) in -1,2 units of the butadiene part of between 4% and 85%, a content (% molar) in trans-1,4 units of the butadiene part comprised between 6% and 80%, a content (mol%) in units -1,2 plus -3,4 of the isoprene part of between 5% and 70% and a content (mol%) in trans-1,4 units of the isoprene part of between 10% and 50%, and more generally any butadiene-styrene-isoprene copolymer having a Tg of between -20 ° C.
• isoprene elastomer is understood to mean, in known manner, a homopolymer or copolymer of isoprene, in other words a diene elastomer chosen from the group consisting of natural rubber (NR) and synthetic polyisoprenes (IR). the different isoprene copolymers and the mixtures of these elastomers.
• isoprene copolymers mention will in particular be made of copolymers of isobutene-isoprene (HR), isoprene-styrene (SIR), isoprene-butadiene (BIR) or isoprene-butadiene-styrene (SBIR) .
• This isoprene elastomer is preferably natural rubber or synthetic cis-1,4 polyisoprene; 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 majority elastomer of the composition according to the invention is a butyl rubber (in particular for applications as inner tire gums), the latter is preferably chosen from the group essentially saturated diene elastomers constituted by isobutene and isoprene copolymers and their halogenated derivatives, this essentially saturated elastomer being able to be used in blending with an elastomer chosen from group of highly unsaturated diene elastomers consisting of polybutadienes (abbreviated "BR"), synthetic polyisoprenes (IR), natural rubber (NR), butadiene copolymers, isoprene copolymers, butadiene-styrene copolymers (SBR), isoprene-butadiene copolymers (BIR), isoprene-styrene copolymers (SIR) and isoprene-butadiene-styrene copolymers (BR)
• BR poly
• the majority elastomer is a substantially unsaturated diene elastomer of the composition according to the invention, the latter is preferably chosen from the group of highly unsaturated diene elastomers constituted by polybutadienes (in particular abbreviated "BR"), synthetic polyisoprenes (IR), natural rubber (NR), butadiene copolymers, isoprene copolymers and mixtures of these elastomers.
• BR polybutadienes
• IR synthetic polyisoprenes
• NR natural rubber
• butadiene copolymers butadiene copolymers
• isoprene copolymers 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) and isoprene-copolymers.
• SBR butadiene-styrene copolymers
• BIR isoprene-butadiene copolymers
• SIR isoprene-styrene copolymers
• SBIR isoprene-copolymers.
• SBIR butadiene-styrene
• the diene elastomer is predominantly (ie, for more than 50 phr) an isoprene elastomer or an SBR, whether it is an emulsion prepared SBR ("ESBR") or a SBR prepared in solution (“SSBR”), or a blend (mixture) SBR / BR, SBR / NR (or SBR / IR), BR / NR (or BR / IR), or SBR / BR / NR (or SBR / BR / IR).
• ESBR emulsion prepared SBR
• SSBR SBR prepared in solution
• an SBR elastomer In the case of an SBR elastomer (ESBR or SSBR), an SBR having an average styrene content, for example between 20% and 35% by weight, or a high styrene content, for example 35 to 35% by weight, is used in particular. 45%, a vinyl ring content of the butadiene part of between 15% and 70%, a content (mol%) of trans-1,4 bonds of between 15% and 75% and a Tg of between -10 ° C. and - 55 ° C; such an SBR can be advantageously used in admixture with a BR preferably having more than 90% (mol%) of cis-1,4 bonds.
• compositions of the invention intended to constitute, in tires, the rubber matrices of certain treads (for example for industrial vehicles), crown reinforcing plies (for example work webs, protective webs or hoop webs), carcass reinforcement webs, flanks, beads, protectors, underlayments, rubber blocks and other internal gums providing the interface between the zones aforementioned tires.
• treads for example for industrial vehicles
• crown reinforcing plies for example work webs, protective webs or hoop webs
• carcass reinforcement webs flanks, beads, protectors, underlayments, rubber blocks and other internal gums providing the interface between the zones aforementioned tires.
• any type of reinforcing filler known for its ability to reinforce a rubber composition that can be used for the manufacture of tires for example an organic filler such as carbon black, a reinforcing inorganic filler such as silica, or cutting of these two types of filler, including a cut of carbon black and silica.
• Carbon blacks are suitable for all carbon blacks, in particular blacks of the HAF, ISAF, SAF type conventionally used in tires (so-called pneumatic grade blacks).
• the reinforcing carbon blacks of the 100, 200 or 300 series for example blacks Nl 15, N134, N234, N326, N330, N339, N347 or N375, or else, according to the targeted applications, the blacks of higher series (for example N660, N683, N772), or even N990.
• the carbon blacks could for example already be incorporated into the isoprene elastomer in the form of a masterbatch (see, for example, applications WO 97/36724 or WO 99 / 16600).
• organic fillers other than carbon blacks
• any inorganic or mineral filler (regardless of its color and origin (natural or synthetic), also called “white” filler, “clear” filler even “non-black filler” as opposed to carbon black, capable of reinforcing on its own, with no other means than an intermediate coupling agent, a rubber composition intended for the manufacture of tires, in other words, able to replace, in its reinforcing function, a conventional carbon black of pneumatic grade, such a charge is generally characterized, in known manner, by the presence of hydroxyl groups (-OH) on its surface.
• -OH hydroxyl groups
• the physical state in which the reinforcing inorganic filler is present is indifferent, whether in the form of powder, microbeads, granules, beads or any other suitable densified form.
• the term "reinforcing inorganic filler” also refers to mixtures of various reinforcing inorganic fillers, in particular highly dispersible siliceous and / or aluminous fillers as described below.
• 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 area both of less than 450 nf / g, preferably 30 to 400 nf / boy Wut.
• HDS highly dispersible precipitated silicas
• 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 the high surface area silicas as described in the application WO 03/16837.
• the reinforcing inorganic filler used in particular if it is silica, preferably has a BET surface area of between 45 and 400. m 2 / g, more preferably between 60 and 300 m 2 / g.
• an at least bifunctional coupling agent is used in known manner to ensure a sufficient chemical and / or physical connection between the inorganic filler ( surface of its particles) and the diene elastomer, in particular organosilanes or bifunctional polyorganosiloxanes.
• 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 known as "symmetrical" silanes having the following general formula (III) are suitable in the following non-limiting definition:
• x is an integer of 2 to 8 (preferably 2 to 5);
• - A is a divalent hydrocarbon radical (preferably alkylene groups C 1 -C 18 or arylene groups C 2 -C 6, particularly alkylene C 1 -C 10, especially C 1 -C 4 alkyl, by especially propylene);
• Z is one of the following formulas:
• the radicals R 1 substituted or unsubstituted, which are identical to or different from each other, represent a C 1 -C 18 alkyl, C 5 -C 18 cycloalkyl or C 6 -C 18 aryl group (preferably alkyl groups containing Ci-C 6, cyclohexyl or phenyl, especially alkyl groups, C1-C4 alkyl, 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 18 alkoxyl or C 5 -C 18 cycloalkoxyl group (preferably a group chosen from C 1 -C 8 alkoxyls and C 5 -C 8 cycloalkoxyls); Cs, more preferably still a group selected from C 1 -C 4 alkoxyls, in particular methoxyl and ethoxyl).
• polysulphurized silanes By way of examples of polysulphurized silanes, mention may be made more particularly of polysulfides (in particular disulfides, trisulphides or tetrasulfides) of bis (C 1 -C 4 alkoxyl) alkyl (C 1 -C 4 ) silyl-alkyl (C 1). -C 4 )), such as polysulfides of bis (3-trimethoxysilylpropyl) or bis (3-triethoxysilylpropyl).
• TESPT bis (3-triethoxysilylpropyl) tetrasulfide
• TESPD bis (3-triethoxysilylpropyl) tetrasulfide
• TESPD bis (3-triethoxysilylpropyl) tetrasulfide
• TESPD bis (triethoxysilylpropyl) disulfide
• polysulfides especially disulfides, trisulphides or in the patent application WO 02/083782 (or US 2004/132880).
• POS polyorganosiloxanes
• the total reinforcing filler content (carbon black and / or reinforcing inorganic filler such as silica) is between 20 and 200 phr, more preferably between 30 and 150 phr, the optimum being in a known manner different according to particular applications targeted: the level of reinforcement expected on a bicycle tire, for example, is of course less than that required on a tire capable of running at high speed in a sustained manner, for example a motorcycle tire, a tire for a passenger vehicle or for commercial vehicles such as heavy goods vehicles.
• carbon black is preferably used as a reinforcing filler in a proportion greater than 30 phr.
• the carbon black content is between 30 and 120 phr, indeed beyond this rate the penalty in terms of rigidity of the composition is too important for an application as a tire inner liner.
• very high ASTM grade carbon blacks such as N990 carbon black, are less reinforcing than 700 grade carbon blacks, and a fortiori 600, and that it is necessary for identical reinforcing of use higher levels of carbon black in the case of 900-grade carbon blacks than in the case of 600- or 700-grade blacks.
• the proportion of carbon black is between 30 and 70 phr, this is particularly the case when using ASTM 600 or 700 grade carbon blacks, and even more preferentially this proportion is between 35 and 60 pce.
• Carbon black may advantageously be the only reinforcing filler or the majority reinforcing filler. Of course, it is possible to use a single carbon black or a blend of several carbon blacks of different ASTM grades.
• the carbon black may also be used in blending with other reinforcing fillers and in particular reinforcing inorganic fillers as described above, and in particular silica.
• graphite is generally meant a set of non-compact hexagonal sheets of carbon atoms: graphenes.
• Graphite a hexagonal crystalline system, has an ABAB type stack where plane B is translated relative to plane A.
• Graphite can not be considered as a reinforcing filler in the sense of the definition specified in paragraph II-2, however it may be considered as a semi-reinforcing filler in that it allows an increase in the modulus in tension of a rubber composition in which it is incorporated.
• graphite that may be used in the compositions according to the invention is more particularly understood to mean: (a) any natural graphite, associated with the rocks affected by metamorphism, after separation of the impurities accompanying the graphite veins and after grinding;
• any thermally expandable natural graphite i.e. in which is interposed one or more chemical compounds in the liquid state, for example an acid, between its graphene planes;
• any expanded natural graphite the latter being produced in two stages: intercalation of one or more chemical compounds in the liquid state, for example an acid, between the graphene planes of a natural graphite by chemical treatment and high temperature expansion;
• any synthetic graphite obtained by graphitization of petroleum coke.
• compositions of the invention may contain a single graphite or a mixture of several graphites, so one can have a blend of natural graphite and / or expanded graphite and / or synthetic graphite.
• Graphite as defined above can be on a morphological plane in a lamellar form or not.
• Graphite is present in the composition according to the invention in levels ranging from 3 phr to 50 phr, and preferably between 5 and 30 phr.
• inert fillers non-reinforcing
• silicon-based lamellar fillers and in particular, phyllosilicates such as smectites, kaolin, talc, mica, vermiculite, etc.
• the rubber compositions of the invention use an extender oil (or plasticizing oil) whose usual function is to facilitate the implementation, by a lowering of the Mooney plasticity and to improve the endurance by a reduction of the modules. lengthening to cooked.
• an extender oil or plasticizing oil
• these oils are liquids (that is to say, as a reminder, substances having the ability to eventually take the shape of their container), as opposed in particular to resins or rubbers which are inherently solid.
• polyisobutylene oils having a number-average molecular weight (Mn) of between 200 g / mol and 40,000 g / mol are used.
• Mn number-average molecular weight
• the abovementioned low molecular weight polyisobutylene oils have demonstrated a much better compromise of properties compared to the other oils tested, in particular to conventional oils of the paraffmic type.
• the polyisobutylene oils have a molecular mass of between 500 g / mol and 35,000 g / mol and more preferably still between 1000 g / mol and 30,000 g / mol.
• polyisobutylene oils are sold in particular by the company UNIVAR under the name "Dynapak PoIy” (eg “Dynapak PoIy 190"), by BASF under the names “Glissopal” (eg “Glissopal 1000") or "Oppanol “(eg” Oppanol B12 "), by Texas Petro Chemical under the name” TPC “(" TPC 1350 "), by Innovene under the name” INDOPOL ".
• the number average molecular weight (Mn) of the polyisobutylene oil is determined by SEC, the sample being solubilized beforehand in tetrahydrofuran at a concentration of about 1 g / L; then the solution is filtered on a 0.45 ⁇ m porosity filter before injection.
• the equipment is the chromatographic chain "WATERS alliance”.
• the elution solvent is tetrahydrofuran, the flow rate of 1 mL / min, The system temperature of 35 ° C and the analysis time of 30 min.
• the injected volume of the solution of the polymer sample is 100 ⁇ L.
• the detector is a differential refractometer "WATERS 2410" and its associated software for the exploitation of chromatographic data is the “WATERS MILLENIUM” system.
• the calculated average molar masses relate to a calibration curve made with polystyrene standards.
• Polyisobutylene oils of low molecular weight suitable for the invention may be functionalized or not.
• certain functionalizations of polyisobutylene oils such as anhydrous polyisobutylene succinic oils, PIBSA, or polyisobutylene succinimide oils, PIBSI, may be mentioned.
• the polyisobutylene oil content is preferably between 2 and 50 phr. Below the minimum indicated, the elastomeric layer or composition may have too high rigidity for certain applications while beyond the maximum recommended, there is a risk of insufficient cohesion of the composition and loss of tightness may be harmful depending on the application.
• the polyisobutylene oil content is even more preferably between 5 and 30 phr.
• the rubber compositions in accordance with the invention may also comprise all or part of the usual additives normally used in elastomer compositions intended for the manufacture of tires or semi-finished products for tires, for example other plasticizers (other than the plasticizer system of the invention), preferably non-aromatic or very weakly aromatic, for example naphthenic, paraffinic oils, MES or TDAE oils, esters (in particular trioleates) of glycerol, in particular natural esters such as vegetable oils of rapeseed or sunflower, pigments, protective agents such as antiozonants, anti-oxidants, anti-fatigue agents, a crosslinking system based on either sulfur or sulfur and / or peroxide donors and or bismaleimides, vulcanization accelerators, vulcanization activators, anti-reversion agents.
• plasticizers other than the plasticizer system of the invention
• non-aromatic or very weakly aromatic for example naphthenic, paraffinic oils, MES or TDAE oils
• compositions may also contain, in addition to the coupling agents, coupling activators, inorganic charge-covering agents or, more generally, processing aids that can be used in a known manner, thanks to an improvement in the dispersion. of the charge in the rubber matrix and a lowering of the viscosity of the compositions, to improve their processability in the state
• agents are, for example, hydrolysable silanes such as alkylalkoxysilanes, polyols, polyethers, primary, secondary or tertiary amines, hydroxylated or hydrolysable polyorganosiloxanes.
• compositions are manufactured in appropriate mixers, using two successive preparation phases well known to those skilled in the art: a first phase of work or thermomechanical mixing at high temperature, up to a maximum temperature of between 110 ° C. and 190 ° C. 0 C, preferably between 130 0 C and 180 0 C, followed by a second phase of mechanical work to a lower temperature, typically less than 110 0 C, for example between 40 0 C and 100 0 C, phase in which the crosslinking system is incorporated.
• the method according to the invention for preparing a rubber composition for an inner tire liner comprises the following steps:
• the first phase is carried out in a single thermomechanical step during which, in a suitable mixer such as a conventional internal mixer, all the necessary basic constituents (elastomer, reinforcing filler) are initially introduced. and coupling agent if necessary, graphite and polyisobutylene oil), then in a second step, for example after one to two minutes of mixing, the other additives, any additional coating or processing agents, with the exception of the system crosslinking.
• a suitable mixer such as a conventional internal mixer
• all the necessary basic constituents elastomer, reinforcing filler
• coupling agent if necessary, graphite and polyisobutylene oil
• the crosslinking system is preferably a vulcanization system based on sulfur and an accelerator. Any compound capable of acting as an accelerator for vulcanizing elastomers in the presence of sulfur, especially those selected from the group consisting of 2-mercaptobenzothiazyl disulfide (abbreviated "MBTS"), N-cyclohexyl-2-benzothiazyl sulfenamide, may be used.
• MBTS 2-mercaptobenzothiazyl disulfide
• N-cyclohexyl-2-benzothiazyl sulfenamide may be used.
• CBS N, N-dicyclohexyl-2-benzothiazyl sulfenamide
• DCBS N-dicyclohexyl-2-benzothiazyl sulfenamide
• TBBS N-tert-butyl-2-benzothiazyl sulfenamide
• TBSI N-tert-butyl- 2-benzothiazyl sulfenimide
• TBS N-tert-butyl- 2-benzothiazyl sulfenimide
• vulcanization activators such as zinc oxide, stearic acid, guanidine derivatives (in particular diphenylguanidine ), etc.
• 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 as an inner tire liner.
• 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 invention relates to the rubber compositions described above both in the so-called “raw” state (i.e., before firing) and in the so-called “cooked” or vulcanized state (i.e. after vulcanization).
• compositions thus obtained are then extruded 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 inner tires of tire.
• This test is intended to show the performance improvement of a composition according to the invention compared to two control compositions of the prior art in terms of rubber properties.
• compositions Al, B1, C1 were prepared in accordance with the method detailed in the preceding paragraph and have the same following base formulation 1 where the amounts are expressed in phr, parts by weight per hundred parts of elastomer:
• compositions Al, Bl and Cl are defined as follows: the control composition A1 is a "conventional" tire inner liner composition that does not include graphite,
• control composition B1 corresponds to a tire inner lining composition containing graphite, like certain documents of the prior art,
• composition C1 according to the present invention comprises graphite and a polyiso butylene oil of low molecular mass in levels according to the invention.
• composition C1 according to the invention comprising graphite and a low molecular weight polyisobutylene oil has in the green state a much better processability (Mooney lower) than the control compositions Al and Bl.
• composition C1 according to the invention has a permeability significantly lower than that of the control composition Al and of the same level as that of the composition B1.
• the modules obtained for the composition C1 according to the invention are generally equivalent to those of the standard control composition Al and the elongation and tensile properties at break are close to those of the control composition Al. that the composition B1 present modules and properties of elongation and breaking stress degraded compared to the control composition Al (and therefore a fortiori compared to the composition C1).
• This improvement of the modules of the composition C1 according to the invention with respect to the composition B1 reflects an improvement in the performance in terms of endurance of the tire whose inner liner has a composition C1 according to the invention.
• composition C1 according to the invention including graphite and a polyisobutylene low molecular weight oil allows a strong improvement of the sealing properties compared to a standard control composition Al and the same level as a control composition Bl having graphite .
• the composition C1 according to the invention makes it possible, with respect to the control compositions Al and B1, to improve the rigidity properties, having consequences on the processability and to improve the endurance, the energy at break (the energy at break being proportional to the product of the elongation at break by the breaking stress) with respect to the composition B1.
• These properties of the composition C1 according to the invention are obtained without degradation of the hysteresis and therefore of the rolling resistance for the tire, neither with respect to the composition A1 nor to the composition B1.
• composition B1 in order to improve the seal by introducing graphite into the composition is achieved to the detriment of other rubber properties.
• compositions A2, C2 and D2 were therefore prepared according to the method described above, and and have a basic formulation corresponding to the detailed one in Example 1, however, they were carried out during a second test, which explains why the results obtained for all the properties measured are not exactly identical to those in Table 2 even for a conventional control composition A2 and a composition according to the invention C2 according to the invention.
• compositions A, C and D are distinguishable from one another as follows:
• control composition A2 is a "conventional" tire interior tire composition that does not include graphite,
• composition C2 according to the invention comprises graphite and a polyisobutylene oil of low molecular mass in levels according to the invention
• the control composition D2 comprises graphite in the same proportion as the composition C2 and a plasticizing resin.
• composition D2 of the prior art of the applicant comprising graphite combined with a plasticizing resin improves compared to the conventional control represented by the composition A2 the properties raw (Mooney), with a slight degradation of the elongation modules and energy properties at break approximately equivalent but at the expense of hysteresis and therefore rolling resistance properties for the tire whose inner liner will have a composition D2.
• composition C2 comprising graphite and a low molecular weight polyisobutylene oil
• the same property improvements as the composition D2 are obtained with respect to the conventional control composition A2 but without degradation. hysteresis and therefore rolling resistance.
• This example is intended to show that the invention is not limited to a single low molecular weight polyisobutylene oil.
• compositions considered have the basic formulation presented in Example 1 and were prepared during the same test as that of Example 1. These compositions are therefore named Al, a standard control composition of the example 1, Cl composition according to the invention identical to that of Example 1 and Fl and Gl two other compositions according to the invention.
• the compositions Cl, Fl and Gl in accordance with the invention comprise all 3 phr of graphite (3) and 10 phr of the polyisobutylene oil of low molecular mass:
• composition Cl it is a non-functionalized polyisobutylene oil "OPPANOL B 12 SFN” marketed by BASF, with a molecular weight of 25,000 g / mol,
• composition F1 non-functionalized polyisobutylene oil
• the two compositions F1 and G1 in accordance with the invention also improve the green properties with respect to the conventional control composition Al as well as the properties with watertightness without degradation of all the other properties (elongation at deformation, energy of rupture, hysteresis).

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