Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L53/00—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
  • C08L53/02—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers of vinyl-aromatic monomers and conjugated dienes
• • 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
• • 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
  • B60C5/00—Inflatable pneumatic tyres or inner tubes
  • B60C5/12—Inflatable pneumatic tyres or inner tubes without separate inflatable inserts, e.g. tubeless tyres with transverse section open to the rim
  • B60C5/14—Inflatable pneumatic tyres or inner tubes without separate inflatable inserts, e.g. tubeless tyres with transverse section open to the rim with impervious liner or coating on the inner wall of the tyre
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
  • C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
  • C08G59/40—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the curing agents used
  • C08G59/62—Alcohols or phenols
  • C08G59/621—Phenols
• • 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
  • C08L25/00—Compositions of, homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Compositions of derivatives of such polymers
  • C08L25/02—Homopolymers or copolymers of hydrocarbons
  • C08L25/04—Homopolymers or copolymers of styrene
  • C08L25/08—Copolymers of styrene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L53/00—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
• • 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
• • 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
  • C08K5/01—Hydrocarbons
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2207/00—Properties characterising the ingredient of the composition
  • C08L2207/32—Properties characterising the ingredient of the composition containing low molecular weight liquid component
  • C08L2207/322—Liquid component is processing oil

Definitions

• the present invention relates to inflatable articles or "pneumatic" objects, i.e., by definition, objects that take their usable form when inflated with air or an equivalent inflation gas.
• the radially inner face has an airtight layer (or more generally any inflation gas) which allows the swelling and maintaining the pressure of the tire.
• airtight layer or more generally any inflation gas
• Its sealing properties enable it to guarantee a relatively low rate of pressure loss, making it possible to maintain the swollen bandage in normal operating condition for a sufficient duration, normally of several weeks or several months. It also serves to protect the carcass reinforcement and more generally the rest of the tire of a risk of oxidation due to the diffusion of air from the internal space to the bandage.
• inner liner waterproof inner liner
• compositions based on rubber or butyl elastomer are well-known disadvantages of compositions based on rubber or butyl elastomer.
• they have significant hysteretic losses, moreover over a wide temperature spectrum, a disadvantage that penalizes the rolling resistance of tires.
• the sealing layer comprises an elastomer composition comprising at least one styrenic thermoplastic elastomer ("TPS") and a filler.
• TPS thermoplastic thermoplastic elastomer
• lamellar at a volume ratio greater than 5% (% by volume of the elastomeric composition).
• the styrenic thermoplastic elastomer has the major advantage, because of its thermoplastic nature, to be able to be worked as is in the molten state (liquid), and therefore to offer a possibility of implementation. simplified work; it has also proved to be compatible with the use of lamellar filler at particularly high levels, which makes it possible to improve the seal compared to the known solutions of the prior art based on butyl rubber.
• compositions in which the use of lamellar fillers is optional the important element being the use of a hydrocarbon resin and an isobutylene block-block block copolymer elastomer. .
• This composition has also been found to be compatible with the use of lamellar filler at particularly high levels, which makes it possible to further improve the seal compared to the known solutions of the prior art.
• the present invention relates to a pneumatic object provided with an elastomeric layer impervious to inflation gases, said layer comprising, as sole elastomer or elastomer by weight, at least one thermoplastic elastomer (" TPE "), and from 0 to 150 phr (parts by weight per hundred parts of elastomer) of an extension oil, in which the single or predominant thermoplastic elastomer is a block copolymer comprising at least one polyisobutylene central block and wherein said layer further comprises a hydrocarbon resin whose glass transition temperature of the hydrocarbon resin is greater than 0 ° C.
• TPE thermoplastic elastomer
• the present invention relates to a pneumatic object as defined above in which the amount of carbonaceous resin is from 5 to 300 phr, very preferably from 10 to 150 phr, and very preferably from 15 to 70 phr.
• the present invention relates to a pneumatic object as defined above in which the glass transition temperature of the hydrocarbon resin is greater than 40 ° C, and more preferably 40 ° C to 160 ° C.
• the present invention relates to a pneumatic object as defined above in which the number-average molecular weight of the block copolymer is between 30,000 and 500,000 g / mol, in the pneumatic object as defined above.
• the polyisobutylene central block copolymer furthermore comprises blocks chosen from polystyrene, polymethylstyrenes, poly-para-tertiobutylstyrene, polychlorostyrenes, polybromostyrenes, polyfluorostyrenes, poly parahydroxystyrene, polyacenaphthylene, polyindene, poly-2-methylindene, poly-3-methylindene, poly-4-methylindene, poly-dimethylindenes, poly-2-phenylindene, poly-3-phenylindene , poly-4-phenylindene, polyisoprene, polymers of esters of acrylic acid, crotonic acid, sorbic acid, methacrylic acid, or polymers of derivatives of acrylamide, methacrylamide, acrylonitrile, and methacrylonitrile.
• the complementary block copolymers of the polyisobutylene block are more particularly chosen from polystyrene, polymethylstyrenes, poly-paratertiobutylstyrene, polychlorostyrenes, polybromostyrenes, polyfluorostyrenes, or poly parahydroxystyrene;
• the block copolymer is a styrene / isobutylene / styrene copolymer.
• this block copolymer comprises between 5 and 50% by weight of styrene.
• the pneumatic object defined above is such that the complementary block copolymers of the polyisobutylene block are chosen from polyacenaphthylene, polyindene, poly-2-methylindene and poly-3- methylindene, poly-4-methylindene, poly-dimethylindenes, poly-2-phenylindene, poly-3-phenylindene, poly-4-phenylindene, polyisoprene, polymers of esters of acrylic acid, crotonic acid, sorbic acid, methacrylic acid, or polymers of the derivatives of acrylamide, methacrylamide, acrylonitrile, and methacrylonitrile.
• the complementary block copolymers of the polyisobutylene block are chosen from polyacenaphthylene, polyindene, poly-2-methylindene and poly-3- methylindene, poly-4-methylindene, poly-dimethylindenes, poly-2-phenylindene, poly-3-pheny
• the present invention relates to a pneumatic object as defined above wherein the glass transition temperature of the block copolymer is less than -20 ° C, and more preferably less than -40 ° C.
• the present invention relates to a pneumatic object as defined above in which the rate of extension oil is less than 150 phr, more preferably less than 100 phr, more preferably still, less than 75 phr and very preferably understood between 5 and 75 pce.
• the extender oil is selected from the group consisting of polyolefinic oils, paraffinic oils, oils and the like. naphthenic, aromatic oils, mineral oils, and mixtures of these oils, more preferably from polybutene oils and very preferably, the extender oil is a polyisobutylene oil.
• the number average molecular weight of the extender oil is between 200 and 25,000 g / mol.
• the pneumatic object as defined above further comprises a lamellar filler, the volume content of which is preferably from 2 to 50%.
• the lamellar filler is selected from the group consisting of graphites, phyllosilicates, and mixtures of such fillers, and more preferably from the group consisting of graphites, talcs, micas, and mixtures of such fillers.
• the pneumatic object defined above is such that the gas-tight layer has a thickness greater than 0.05 mm, and more particularly between 0.1 mm and 10 mm.
• this gas-tight layer is disposed on the inner wall of the pneumatic object.
• the pneumatic object as defined above is rubber, and it is more preferably a tire.
• said pneumatic object is an air chamber, and more particularly, a tire air chamber.
• the invention relates more particularly to pneumatic tires intended for equipping tourism-type motor vehicles, SUVs ("Sport Utility Vehicles"), two wheels (in particular motorcycles), planes, such as industrial vehicles chosen from light trucks, "heavy vehicles "- that is, metros, buses, road transport vehicles (trucks, tractors, trailers), off-the-road vehicles such as agricultural or civil engineering machinery - other transport or handling vehicles.
• the invention also relates to a method for sealing a pneumatic object vis-à-vis the inflation gases, wherein is incorporated in said pneumatic object during its manufacture, or is added to said pneumatic object after its manufacture, a gas-tight layer such as as defined above.
• the invention also relates to the use as an inflation-tight layer, in a pneumatic object, of an elastomeric composition as defined above.
• 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 pneumatic object according to the invention has the essential feature of being provided with an inflation-gas-tight layer comprising an elastomer composition comprising at least, as sole elastomer or elastomer, by weight present in said composition, a thermoplastic elastomer (TPE), styrene (TPS) or non-styrenic (TPNS) and preferably styrenic, which is associated with a hydrocarbon resin, and optionally an extension oil of said elastomer from 0 to 150 phr (parts by weight per hundred parts) elastomer).
• TPE thermoplastic elastomer
• TPS styrene
• TPNS non-styrenic
• extension oil of said elastomer from 0 to 150 phr (parts by weight per hundred parts) elastomer).
• Thermoplastic elastomers have an intermediate structure between thermoplastic polymers and elastomers. They are block copolymers consisting of rigid thermoplastic blocks connected by flexible elastomeric blocks, for example polybutadiene, polyisoprene, poly (ethylene / butylene) or polyisobutylene. They are often triblock elastomers with two rigid segments connected by a flexible segment. The rigid and flexible segments can be arranged linearly, star or connected.
• each of these segments or blocks often contains at least more than 5, usually more than 10 base units (e.g., styrene units and isobutylene units for a styrene / isobutylene / styrene block copolymer).
• base units e.g., styrene units and isobutylene units for a styrene / isobutylene / styrene block copolymer.
• the flexible elastomeric blocks consist mainly of "polyisobutylene" blocks.
• the thermoplastic elastomeric block copolymer is in a linear triblock form.
• the block copolymer can then consist of a central "polyisobutylene” block and two terminal thermoplastic blocks, at each of the two ends of the "polyisobutylene” block.
• the thermoplastic elastomeric block copolymer is in a star shape with at least three branches.
• the block copolymer can then consist of a "polyisobutylene” block starry at least three branches and a thermoplastic block, located at the end of each of the branches of "polyisobutylene".
• the number of branches of the "polyisobutylene" may vary for example from 3 to 12, and preferably from 3 to 6.
• thermoplastic elastomeric block copolymer is in a branched or dendrimer form.
• the block copolymer can then consist of a connected "polyisobutylene” block or dendrimer and a thermoplastic block, located at the end of the branches of the "polyisobutylene” dendrimer.
• thermoplastic elastomer used for the implementation of the invention is a block copolymer comprising at least one polyisobutylene central block, denoted Block Copolymer.
• Block Copolymer Depending on the case, it can also be of two types depending on whether or not it comprises a styrenic block in addition to the polyisobutylene block or blocks.
• Thermoplastics according to the invention TPIBS (Thermoplastics with isobutylenic and styrenic blocks) or TPIBNS (Thermoplastics with isobutylenic blocks and non-styrenic blocks) are then noted.
• the number-average molecular weight (denoted Mn) of the Block Copolymer is preferably between 30,000 and 500,000 g / mol, more preferably between 40,000 and 400,000 g / mol.
• Mn number-average molecular weight
• the number-average molecular weight (Mn) of the TPE elastomer is determined in known manner by steric exclusion chromatography (SEC).
• SEC steric exclusion chromatography
• the sample is first solubilized in tetrahydrofuran at a concentration of about 1 g / l; then the solution is filtered on 0.45 ⁇ porosity filter before injection.
• the apparatus used is a "WATERS alliance" chromatographic chain.
• the elution solvent is tetrahydrofuran, the flow rate 0.7 ml / min, the system temperature 35 ° C and the analysis time 90 min.
• a set of four WATERS columns in series, of trade names "STYRAGEL"("HMW7","HMW6E" and two "HT6E" is used.
• the injected volume of the solution of the polymer sample is 100 ⁇ .
• the detector is a "WATERS 2410" differential refractometer 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.
• the "polyisobutylene” block of the Block Copolymer is composed mainly of units derived from isobutene.
• a monomer weight ratio relative to the total weight of the "polyisobutylene” block and preferably a weight content of more than 50%, more preferably of more than 75% and even more preferentially of more than 85%.
• the "polyisobutylene" block of the Block Copolymer has a number-average molecular weight ("Mn") ranging from 25,000 g / mol to 350,000 g / mol, preferably from 35,000 g / mol to 250,000 g. / mol so as to give the TPE good elastomeric properties and sufficient mechanical strength and compatible with the internal rubber sealing application of a tire.
• Mn number-average molecular weight
• such copolymers have two glass transition temperature peaks (Tg, measured according to ASTM D3418), the lowest temperature, negative being relative to the "polyisobutylene" block copolymer block, and the highest temperature, positive, typically greater than or equal to 80 ° C being relative to the thermoplastic part (styrenic or non-styrenic) of the Block Copolymer.
• Tg glass transition temperature
• the Block Copolymer preferably has a glass transition temperature ("Tg") which is preferably less than or equal to -20 ° C, more preferably less than or equal to -40 ° C.
• Tg glass transition temperature
• a value of Tg higher than these minima can reduce the performance of the waterproof layer during use at very low temperatures; for such use, the Tg of the Block Copolymer is more preferably less than or equal to -50 ° C.
• the "polyisobutylene" block of the Block Copolymer may also comprise one or more conjugated dienes inserted into the polymer chain.
• the rate of units derived from dienes is defined by the sealing properties that the Block copolymer.
• the proportion of units derived from dienes ranges from 0.5 to 16% by weight relative to the weight of the "polyisobutylene” block, more preferably from 1 to 10% by weight and even more preferably from 2 to 8% by weight. % by weight relative to the weight of the "polyisobutylene" block.
• Conjugated dienes that can be copolymerized with isobutylene to form the "polyisobutylene" block are preferably C4-C14 conjugated dienes.
• these conjugated dienes are chosen from isoprene, butadiene, piperylene, 1-methylbutadiene, 2-methylbutadiene, 2,3-dimethyl-1,3-butadiene and 2,4-dimethyl-1.
• the "polyisobutylene” block can be halogenated and comprise halogen atoms in its chain. This halogenation makes it possible to increase the rate of crosslinking of the composition comprising the Block Copolymer.
• Halogenation is by means of bromine or chlorine, preferably bromine, on the units derived from conjugated dienes of the polymer chain of the "polyisobutylene" block. Only a part of these units reacts with halogen. This portion of units derived from reactive conjugated dienes is preferably such that the proportion of units derived from unreacted conjugated dienes with halogen is at least 0.5% by weight relative to the weight of the block.
• thermoplastic elastomer Comprising a Styrenic Block (TPIBS)
• TPIBS Styrenic Block
• a thermoplastic elastomer which is a Block Copolymer comprising at least one polyisobutylene central block and adjacent blocks consisting of at least one polymerized styrene monomer.
• styrenic monomer any monomer based on styrene, unsubstituted as substituted; among the substituted styrenes may be mentioned, for example, methylstyrenes (for example ⁇ -methylstyrene, m-methylstyrene or p-methylstyrene, alpha-methylstyrene, alpha-2-dimethylstyrene, alpha-4-dimethylstyrene or diphenylethylene), para-tert-butylstyrene, chlorostyrenes (e.g., ⁇ -chlorostyrene, m-chlorostyrene, p-chlorostyrene, 2,4-dichlorostyrene, 2,6-dichlorostyrene or 2,4,6-dichlorostyrene).
• methylstyrenes for example ⁇ -methylstyrene, m-methylstyrene or p-methyl
• bromostyrenes eg bromostyrene, m-bromostyrene, p-bromostyrene, 2,4-dibromostyrene, 2,6-dibromostyrene or 2,4,6-tribromostyrene
• fluorostyrenes eg, o-fluorostyrene, fluorostyrene, p-fluorostyrene, 2,4-difluorostyrene, 2,6-difluoro styrene or 2,4,6-trifluorostyrene
• para-hydroxy-styrene eg, o-fluorostyrene, fluorostyrene, p-fluorostyrene, 2,4-difluorostyrene, 2,6-difluoro styrene or 2,4,6-trifluorostyrene
• the elastomer according to this first variant of the invention may be chosen in particular from the group consisting of styrene / isobutylene / styrene block copolymers (SIBS).
• SIBS styrene / isobutylene / styrene block copolymers
• elastomer or copolymer SIBS is meant in the present application, by definition, any styrene / isobutylene / styrene triblock elastomer in which the polyisobutylene central block may be interrupted or not by one or more unsaturated units, in particular one or more diene units such as isoprenic, possibly halogenated.
• the weight content of styrene in the TPIBS elastomer is between 5% and 50%. Below the minimum indicated, the thermoplastic nature of the elastomer may decrease significantly while above the maximum recommended, the elasticity of the seal layer may be affected. For these reasons, the styrene content is more preferably between 10% and 40%, in particular between 15 and 35%.
• the glass transition temperature (Tg, measured according to ASTM D3418) of the TPIBS elastomer is less than -20 ° C, more preferably less than -40 ° C.
• Tg higher than these minima can reduce the performance of the waterproof layer during use at very low temperatures; for such use, the Tg of the TPIBS elastomer is more preferably still lower than -50 ° C.
• the TPIBS elastomer and the resin may constitute by themselves the gas-tight elastomeric layer or may be associated in the elastomer composition with other elastomers. If any other elastomers are used in the composition, the TPIBS elastomer constitutes the majority elastomer by weight; it then preferably represents more than 50%, more preferably more than 70% by weight of all the elastomers present in the elastomer composition.
• Such complementary elastomers, minority by weight could be, for example, diene elastomers such as natural rubber or synthetic polyisoprene, butyl rubber or thermoplastic elastomers other than styrenic, within the limit of the compatibility of their microstructures.
• the TPIBS elastomer in particular SIBS, is the only elastomer, and the only thermoplastic elastomer present in the elastomeric composition of the gas-tight layer.
• the TPIBS elastomers can be implemented in a conventional manner for TPE, by extrusion or molding, for example from a raw material available in the form of beads or granules.
• TPIBS elastomers are commercially available, sold for example as regards SIBS by KANEKA under the name "SIBSTAR" (e.g. "Sibstar 102T", “Sibstar 103T” or “Sibstar 073T”). For example, they have been described, as well as their synthesis, in patent documents EP 731 112, US Pat. No. 4,946,899 and US Pat. No. 5,260,383. They were first developed for biomedical applications and then described in various applications specific to elastomers.
• TPE as varied as medical equipment, parts for automobiles or household appliances, sheaths for electrical wires, sealing pieces or elastics (see for example EP 1 431 343, EP 1 561 783, EP 1 566 405, WO 2005/103146) . Subsequently, these elastomers have been described for applications in the field of tires (see for example WO2008 / 145276, WO2008 / 145277, WO2009 / 007064).
• thermoplastic elastomer having a specific block other than styrenic (TPIBNS)
• TPIBNS thermoplastic elastomer which is a Block Copolymer comprising at least one polyisobutylene central block and adjacent blocks consisting of at least one polymerized monomer , other than a styrenic monomer, the glass transition temperature (Tg, measured according to ASTM D3418) of said non-styrenic polymer constituting the thermoplastic block of the Block Copolymer is greater than or equal to 100 ° C.
• the Block Copolymer preferably has the following structural features:
• the "polyisobutylene” block has a number-average molecular weight (“Mn”) ranging from 25,000 g / mol to 350,000 g / mol and a glass transition temperature (“Tg”) of less than or equal to -20 ° C. ,
• the adjacent thermoplastic blocks consist of at least one polymerized monomer, other than a styrenic monomer, and have a higher glass transition temperature ("Tg") greater than or equal to 100 ° C.
• thermoplastic blocks preferably have a Tg greater than or equal to 100 ° C. According to a preferred aspect of the invention, the Tg of the thermoplastic block is greater than or equal to 130 ° C., still more preferably greater than or equal to 150 ° C., or even greater than or equal to 200 ° C.
• the proportion of the thermoplastic blocks with respect to the Block Copolymer is determined on the one hand by the properties of thermoplasticity that must present said copolymer.
• the thermoplastic blocks having a Tg greater than or equal to 100 ° C are preferably present in proportions sufficient to preserve the thermoplastic nature of the elastomer according to the invention.
• the minimum level of thermoplastic blocks having a Tg greater than or equal to 100 ° C of the Block Copolymer may vary depending on the conditions of use of the copolymer.
• the ability of the Block Copolymer to deform during the conformation of the tire can also contribute to determining the proportion of thermoplastic blocks having a Tg greater than or equal to 100 ° C.
• thermoplastic block having a Tg greater than or equal to 100 ° C any polymer based on at least one polymerized monomer other than a styrenic monomer, whose glass transition temperature is greater than or equal to at 100 ° C.
• polymerized monomer other than a styrene monomer must be understood in the present description, any monomer, other than a styrenic monomer, polymerized according to techniques known to those skilled in the art and may lead to the preparation of a Block Copolymer such that used for the implementation of the invention.
• the polymerized monomers other than styrene monomers according to the invention and which can be used for the preparation of thermoplastic blocks having a Tg greater than or equal to 100 ° C. can be chosen from the following compounds and their mixtures: - Pacenapthylene.
• Those skilled in the art may, for example, refer to the article by Z. Fodor and JP Kennedy, Polymer Bulletin 1992 29 (6) 697-705;
• indene and its derivatives such as, for example, 2-methylindene, 3-methylindene, 4-methylindene, dimethylindene, 2-phenylindene, 3-phenylindene and 4-phenylindene.
• indene and its derivatives such as, for example, 2-methylindene, 3-methylindene, 4-methylindene, dimethylindene, 2-phenylindene, 3-phenylindene and 4-phenylindene.
• Those skilled in the art may for example refer to the patent document US4946899, by the inventors Kennedy, Puskas, Kaszas and Hager and the documents JE Puskas, G. Kaszas, JP Kennedy, WG Hager Journal of Polymer Science Part A: Polymer Chemistry (1992) 30, 41 and JP Kennedy, N. Meguriya, B. Keszler, Macromolecules (1991) 24 (25), 6572-6577;
• adamantyl acrylate Mention may be made more particularly of adamantyl acrylate, adamantyl crotonate, adamantyl sorbate, 4-biphenyl acrylate, tert-butyl acrylate, cyanomethyl acrylate and acrylate.
• the polymerized monomer other than a styrenic monomer may be copolymerized with at least one other monomer so as to form a thermoplastic block having a Tg greater than or equal to 100 ° C.
• the molar fraction of polymerized monomer other than a styrenic monomer, relative to the total number of units of the thermoplastic block must be sufficient to reach a Tg greater than or equal to 100 ° C., preferably greater than or equal to 130 ° C. C, still more preferably greater than or equal to 150 ° C, or even greater than or equal to 200 ° C.
• the molar fraction of this other comonomer may range from 0 to 90%, more preferably from 0 to 75% and even more preferably from 0 to 50%.
• this other monomer capable of copolymerizing with the polymerized monomer other than a styrenic monomer may be chosen from the diene monomers, more particularly, the conjugated diene monomers having 4 to 14 carbon atoms, and the vinylaromatic type monomers having 8 to 20 carbon atoms.
• the comonomer is a conjugated diene having 4 to 12 carbon atoms
• it advantageously represents a mole fraction relative to the total number of units of the thermoplastic block ranging from 0 to 25%.
• conjugated dienes that may be used in the thermoplastic blocks according to the invention, those described above, namely isoprene, butadiene, 1-methylbutadiene, 2-methylbutadiene, 2,3-dimethyl-1,3- butadiene, 2,4-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene, 4-methyl-1 , 3-pentadiene, 2,3-dimethyl-1,3-pentadiene, 2,5-dimethyl-1,3-pentadiene, 1,3-hexadiene, 2-methyl-1,3-hexadiene, 3-methyl-1,3-hexadiene, 4-methyl-1,3-hexad
• the comonomer is of vinylaromatic type, it advantageously represents a fraction in units on the total number of units of the thermoplastic block from 0 to 90%, preferably ranging from 0 to 75% and even more preferably ranging from 0 to 50%.
• vinylaromatic compounds are particularly suitable styrenic monomers mentioned above, namely methylstyrenes, para-tert-butylstyrene, chlorostyrenes, bromostyrenes, fluorostyrenes or para-hydroxy-styrene.
• the vinylaromatic comonomer is styrene.
• thermoplastic blocks having a Tg greater than or equal to 100 ° C. consisting of indene and styrene derivatives. especially para-methylstyrene or para-tertiobutyl styrene.
• Block Copolymers as defined for the practice of the invention may be prepared by known synthetic methods. Those skilled in the art will be able to choose the appropriate polymerization conditions and regulate the various parameters of the polymerization processes in order to achieve the specific structural characteristics of the Block Copolymer useful for the implementation of the invention. Several synthetic strategies can be implemented to prepare the copolymers useful for the implementation of the invention.
• a first consists in a first step of synthesis of the "polyisobutylene" block by living cationic polymerization of the monomers to be polymerized by means of a monofunctional, di-functional or polyfunctional initiator known to those skilled in the art, followed by of the second step of synthesis of the thermoplastic block or blocks having a Tg greater than or equal to 100 ° C and by adding the monomer to be polymerized on the living polyisobutylene obtained in the first step.
• these two steps are consecutive, which results in the sequenced addition:
• the monomer (s) to be polymerized may or may not be added in the form of a solution in a solvent as described below, in the presence or absence of an acid or a Lewis base as described below.
• Each of these steps can be carried out in the same reactor or in two different polymerization reactors. Preferably, these two steps are performed in a single reactor (synthesis "one-pot").
• the living cationic polymerization is conventionally carried out by means of a difunctional or polyfunctional initiator and optionally of a Lewis acid acting as a co-initiator in order to form a carbocation in situ. Electro-donor compounds are usually added to give the polymerization a living character.
• the di-functional or polyfunctional initiators which can be used for the preparation of the copolymers according to the invention can be chosen from 1,4-di (2-methoxy-2-propyl) -benzene (or "dicumylmethyl ether”).
• the Lewis acids may be chosen from metal halides, of general formula MXn where M is an element chosen from Ti, Zr, Al, Sn, P, B, and X is a halogen such as Cl, Br, F or I and n is the oxidation state of the element M may be mentioned for example T1CI4, A1C1 3, BC1 3, BF 3, SnCl, PC1 3, PC1 5. Among these compounds T1CI4, A1C1 3 and BC1 3 are used preferentially, and TiCl 4 even more preferentially.
• the electro-donating compounds may be selected from known Lewis bases, such as pyridines, amines, amides, esters, sulfoxides and others. Among them are preferred DMSO (dimethylsulfoxide) and DMAc (dimethylacetamide).
• the living cationic polymerization is carried out in an apolar inert solvent or in a mixture of polar and nonpolar inert solvents.
• apolar solvents which can be used for the synthesis of the copolymers according to the invention are, for example, hydrocarbon, aliphatic, cycloaliphatic or aromatic solvents, such as hexane, heptane, cyclohexane, methylcyclohexane, benzene or toluene.
• polar solvents which can be used for the synthesis of the copolymers according to the invention are, for example, halogenated solvents such as alkane halides, such as methyl chloride (or chloroform), ethyl chloride, butyl chloride, methylene chloride (or dichloromethane) or chlorobenzenes (mono-, di- or tri-chloro).
• alkane halides such as methyl chloride (or chloroform), ethyl chloride, butyl chloride, methylene chloride (or dichloromethane) or chlorobenzenes (mono-, di- or tri-chloro).
• thermoplastic block elastomeric copolymers according to the invention as well as the appropriate temperature conditions in order to achieve the molar mass characteristics of these compounds. copolymers.
• a telechelic or functional "polyisobutylene" block at one or more of its chain ends by living cationic polymerization by means of a monofunctional, difunctional or polyfunctional initiator, optionally followed by a functionalization reaction on a or more ends of strings,
• thermoplastic block or blocks for example by anionic polymerization, and having a Tg greater than or equal to 100 ° C.
• a third synthesis strategy consists of realizing in this order:
• a monomeric unit that can be lithiated and lead to a species capable of initiating anionic polymerization such as, for example, 1,1-diphenylethylene;
• the halogenation of the copolymer according to the invention is carried out according to any method known to those skilled in the art, in particular those used for the halogenation of butyl rubber and may be carried out for example by means of bromine or chlorine, preferably bromine, on the units derived from conjugated dienes of the polymeric chain of the "polyisobutylene" block and / or of the thermoplastic block or blocks.
• the thermoplastic elastomer is starred or still connected
• the processes described for example in the articles of Puskas J. Polym. Sci Part A: Polymer Chemistry, Vol 36, pp85-82 (1998) and Puskas, J. Polym. Sci Part A: Polymer Chemistry, vol 43, ppl811-1826 (2005) can be implemented by analogy to obtain "polyisobutylene" blocks starred, branched or living dendrimers.
• the composition of the monomer mixtures to be used in order to prepare the copolymers according to the invention will be chosen as well as the appropriate temperature conditions in order to achieve the molar mass characteristics of these copolymers.
• the preparation of the copolymers according to the invention will be carried out by living cationic polymerization using a difunctional or polyfunctional initiator and by sequential additions of the monomers to be polymerized for the synthesis of the "polyisobutene" block and the monomers to be polymerized for the synthesis of the thermoplastic block or blocks having a Tg greater than or equal to 100 ° C.
• thermoplastic block elastomer according to the invention TPIBS or TPIBNS as defined above can constitute in itself the elastomeric composition or be associated, in this composition, with other constituents to form an elastomeric matrix. If any other elastomers are used in this composition, the Block Copolymer as described above constitutes the majority elastomer by weight, that is to say that the weight fraction of the Block Copolymer relative to all the elastomers is the highest.
• the Block Copolymer preferably represents more than 50%, more preferably more than 70% by weight of all the elastomers.
• Such complementary elastomers could be, for example, diene elastomers or thermoplastic styrene elastomers (TPS), within the limit of the compatibility of their microstructures.
• diene elastomers that may be used in addition to the Block Copolymer previously described, mention may be made especially of polybutadienes (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), isoprene-isobutylene copolymers ( IIR), isoprene-butadiene-styrene copolymers (SBIR) and mixtures of such copolymers.
• SBR butadiene-styrene copolymers
• BIR isoprene-butadiene copolymers
• SIR isoprene-styrene copolymers
• IIR isoprene-isobutylene copolymers
• SBIR isoprene-butadiene-styrene copolymers
• TPS elastomer chosen from the group consisting of styrene / butadiene / styrene block copolymers (SBS) and styrene / isoprene / styrene block copolymers (SIS), styrene / butylene / styrene, styrene block copolymers butadiene / isoprene / styrene (SBIS), styrene / ethylene / butylene / styrene block copolymers (SEBS), styrene / ethylene / propylene / styrene block copolymers (SEPS), styrene / ethylene / ethylene / propylene block copolymers st
• the second essential constituent of the sealed composition is a hydrocarbon resin.
• 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 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 can be aliphatic, cycloaliphatic, aromatic, hydrogenated aromatic, aliphatic / aromatic type that is to say based on aliphatic and / or aromatic monomers.
• Tg is preferably greater than 0 ° C., especially greater than 20 ° C. (most often between 30 ° C. and 120 ° 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 ("softening point"), the temperature at which the product, for example in the form of powder, agglutinates.
• 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 160 ° C), more preferably greater than 50 ° C (in particular between 50 ° C). C and 150 ° C).
• Said resin is preferably used at a weight ratio ranging from 5 to 600 phr.
• the level of resin is preferably from 5 to 300 phr, more preferably from 10 to 150 phr, more preferably from 10 to 100 phr and very preferably from 15 to 70 phr. Even more preferably, the weight ratio of hydrocarbon resin is 25 to 70 phr.
• the hydrocarbon resin has at least one, more preferably all of the following characteristics: a Tg greater than 10 ° C, and more preferably greater than 30 ° C;
• a softening point greater than 50 ° C, preferably greater than 80 ° C (in particular between 80 ° C and 160 ° C);
• Mn number-average molar mass
• Ip polymolecularity index
• this hydrocarbon resin has at least any one, more preferably all of the following characteristics: a Tg between 30 ° C and 120 ° C (especially between 35 ° C and 105 ° C);
• a softening point greater than 90 ° C, in particular between 110 ° C and 150 ° C;
• the softening point is measured according to ISO 4625 ("Ring and Bail” method). Tg is measured 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 ° 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”).
• hydrocarbon resins By way of examples of such hydrocarbon resins, mention may be made of those selected from the group consisting of homopolymer or copolymer resins of cyclopentadiene (abbreviated as CPD) or dicyclopentadiene (abbreviated to DCPD), terpene homopolymer or copolymer resins. terpene phenol homopolymer or copolymer resins, homopolymer or C5 cut copolymer resins, homopolymer or C9 cut copolymer resins, alpha-methyl-styrene homopolymer or copolymer resins and blends 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; preferably, a limonene monomer is used which is present in a known manner in the form of three possible isomers: L-limonene (laevorotatory enantiomer), D-limonene (dextrorotatory enantiomer), or the dipentene, racemic of the dextrorotatory and levorotatory enantiomers. .
• Suitable vinylaromatic monomers are, for example, styrene, alpha-methylstyrene, ortho-methylstyrene, meta-methylstyrene, para-methylstyrene, vinyl-toluene, para-tert-butylstyrene, methoxystyrenes, chlorostyrenes, hydroxystyrenes, vinylmesitylene, divinylbenzene, vinylnaphthalene, any vinylaromatic monomer resulting from a C9 cut (or more generally from a C8 to C10 cut).
• 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 TPE elastomer and the resin alone are sufficient for the gas-tight function to be performed with respect to the pneumatic objects in which they are used.
• the elastomer composition described above also comprises, as plasticizer, an extender oil (or plasticizing oil) at a rate at most equal to 150 phr, and preferably less than 150 phr, whose function is to facilitate the implementation of the gas-tight layer, particularly its integration into the pneumatic object by a lowering of the module and an increase in the tackifying power.
• an extender oil or plasticizing oil
• any extension oil preferably of a slightly polar nature, capable of extending and plasticizing elastomers, especially thermoplastics, may be used. At room temperature (23 ° C), these oils, more or less viscous, 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.
• the extender oil is chosen from the group consisting of polyolefinic oils (that is to say from the polymerization of olefins, monoolefins or diolefins), paraffinic oils, naphthenic oils (low or high viscosity), aromatic oils, mineral oils, and mixtures of these oils. If it was found that the addition of oil was done at the cost of a certain loss of sealing, variable depending on the type and amount of oil used, this leakage can be largely corrected by adjusting the lamellar charge rate.
• a polybutene-type oil is preferably used, in particular a polyisobutylene oil (abbreviated to "PIB"), which has demonstrated the best compromise of properties compared to the other oils tested, in particular to a conventional oil of the paraffmic type.
• PIB polyisobutylene oil
• polyisobutylene oils are sold in particular by the company UNIVAR under the name "Dynapak Poly” (eg "Dynapak Poly 190"), by INEOS Oligomer under the name “Indopol H 1200", by BASF under the names “ Glissopal “(eg” Glissopal 1000 ") or” Oppanol “(eg” Oppanol B12 "); paraffinic oils are marketed for example by EXXON under the name "Telura 618" or by Repsol under the name "Extensol 51".
• the number-average molecular mass (Mn) of the extender oil is preferably between 200 and 25,000 g / mol, more preferably between 300 and 10,000 g / mol.
• Mn number-average molecular mass
• the number average molecular weight (Mn) of the extender 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 0.45 ⁇ porosity filter before injection.
• the equipment is the chromatographic chain "WATERS alliance”.
• the elution solvent is tetrahydrofuran, the flow rate is 1 ml / min, the temperature of the system is 35 ° C. and the analysis time is 30 minutes.
• the injected volume of the solution of the polymer sample is 100 ⁇ .
• 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.
• the extender oil content be less than 150 phr (parts by weight per hundred parts of total elastomer, that is, TPE elastomer plus any other elastomer present in the composition or elastomeric layer).
• the extender oil content is less than 150 phr, preferably less than 100 phr, more preferably less than 75 phr, and very preferably between 5 and 75 phr.
• a platy filler rate can be used.
• the so-called lamellar fillers in English "platy fillers" are well known to those skilled in the art. They have been used in particular in pneumatic tires to reduce the permeability of conventional gastight layers based on butyl rubber. In these butyl-based layers, they are generally used at relatively low levels, usually not exceeding 10 to 15 phr (see, for example, US Patent Specification 2004/0194863, WO 2006/047509).
• L L / E
• L the length (or greater dimension)
• E the average thickness of these lamellar fillers, these averages being calculated in number. Form ratios of tens or even hundreds are common.
• Their average length is preferably greater than 1 ⁇ (that is to say that it is then micrometric said lamellar charges), typically between a few ⁇ (for example 5 ⁇ ) and a few hundreds of ⁇ (by example 500 or 800 ⁇ ).
• the lamellar fillers used in accordance with the invention are chosen from the group consisting of graphites, phyllosilicates and mixtures of such fillers.
• phyllosilicates there may be mentioned clays, talcs, micas, kaolins, these phyllosilicates may or may not be modified for example by a surface treatment; examples of such modified phyllosilicates include micas coated with titanium oxide, clays modified with surfactants ("organo clays").
• Lamellar fillers with a low surface energy are preferably used, such as those chosen from the group consisting of graphites, talcs, micas and mixtures of such fillers, the latter being able to be modified or not, more preferably still in the group consisting of graphites, talcs and mixtures of such fillers.
• graphites can be mentioned including natural graphites, expanded graphites or synthetic graphites.
• micas that may be mentioned include micas marketed by Yamaguchi (A51S, A41S, SYA-21R, SYA-21RS, A21S, SYA-41R), or by CMMP (Mica-MU®, Mica-Soft).
• the lamellar fillers described above are used at a content preferably less than 30% and more preferably from 2% to 20% by volume of elastomer composition.
• Such a volume ratio typically corresponds, given the average density of the lamellar charges used (typically between 2.0 and 3.0), that of the TPS elastomers used and a plasticizer content of 40%> (67 phr). , at a rate ranging from 0 to 250 phr, preferably from 10 to 150 phr.
• the introduction of the lamellar fillers into the elastomeric thermoplastic composition can be carried out according to various known methods, for example by mixing in solution, by mass mixing in an internal mixer, or by extrusion mixing.
• the airtight layer or composition described above may also include the various additives usually present in the airtight layers known to those skilled in the art.
• reinforcing fillers such as carbon black or silica
• coloring agents that can be advantageously used for coloring the composition
• plasticizers other than oils may be mentioned.
• protection agents such as antioxidants or antiozonants, anti-UV, various processing agents or other stabilizers, or promoters capable of promoting adhesion to the rest of the structure of the pneumatic object.
• the gas-tight layer or composition previously described is a solid (at 23 ° C.) and elastic compound, which is particularly characterized, thanks to its specific formulation, by a very high flexibility and very high deformability. 1-2. Use of the airtight layer in a tire
• TPE elastomer composition can be used as an airtight layer in any type of pneumatic object.
• pneumatic objects include pneumatic mattresses, inflatable boats, balls or balls used for play or sport.
• Such an airtight layer is preferentially disposed on the inner wall of the pneumatic object, but it can also be completely integrated into its internal structure.
• the thickness of the airtight layer is preferably greater than 0.05 mm, more preferably between 0.1 mm and 10 mm (in particular between 0.1 and 1.0 mm).
• the airtight layer has the advantage of having not only a lower hysteresis, and thus to offer a reduced rolling resistance. pneumatic tires, but still a seal at least equal if not greatly improved, as is demonstrated in the following embodiments.
• the gas-tight layer previously described is advantageously usable in tire tires of all types of vehicles, in particular passenger vehicles or industrial vehicles such as heavy vehicles.
• the single appended figure shows very schematically (without respecting a specific scale), a radial section of a tire according to the invention.
• This tire 1 has a crown 2 reinforced by a crown reinforcement or belt 6, two sidewalls 3 and two beads 4, each of these beads 4 being reinforced with a rod 5.
• the crown 2 is surmounted by a tread represented in this schematic figure.
• a carcass reinforcement 7 is wound around the two rods 5 in each bead 4, the upturn 8 of this armature 7 being for example disposed towards the outside of the tire 1 which is shown here mounted on its rim 9.
• the carcass reinforcement 7 is in known manner constituted of at least one sheet reinforced by so-called "radial” cables, for example textile or metal, that is to say that these cables are arranged substantially parallel to each other and s' extend from one 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 goes through the middle of the crown frame 6).
• radial cables for example textile or metal
• the inner wall of the tire 1 comprises an airtight layer 10, for example of a thickness equal to about 0.9 mm, on the side of the internal cavity 11 of the tire 1.
• This inner layer covers the entire inner wall of the tire, extending from one side to the other, at least to the level of the rim hook when the tire is in the mounted position. It defines the radially inner face of said tire intended to protect the carcass reinforcement from the diffusion of air coming from the space 11 inside the tire. It allows inflation and pressure maintenance of the tire; its sealing properties must enable it to guarantee a relatively low rate of pressure loss, to maintain the swollen bandage, in normal operating condition, for a sufficient duration, normally of several weeks or several months.
• the tire according to the invention uses in this example, as airtight layer, an elastomeric composition comprising a SIBS elastomer ("Sibstar 102T" with a styrene content of about 15%, a Tg of about -65 ° C.
• SIBS elastomer SIBS elastomer
• the tire provided with its airtight layer (10) as described above can be made before or after vulcanization (or cooking).
• the airtight layer is simply conventionally applied to the desired location, for formation of the layer 10.
• Vulcanization is then performed conventionally.
• the described TPE elastomers support the constraints related to the vulcanization step.
• An advantageous manufacturing variant for those skilled in the tire industry, will for example consist in a first step of laying the airtight layer directly on a manufacturing drum in the form of a flat tire. a layer (“skim”) of suitable thickness, before covering the latter with the rest of the structure of the tire, according to manufacturing techniques well known to those skilled in the art.
• the sealing layer is applied inside the baked tire by any appropriate means, for example by gluing, spraying or else extruding and blowing a film of appropriate thickness.
• the sealing properties were analyzed on specimens of compositions based on TPE elastomer (with and without extension oil, with regard to the TPE elastomer, with and without lamellar fillers, with and without resin and at variable rates).
• a rigid wall permeameter was used, placed in an oven (temperature 60 ° C in this case), equipped with a relative pressure sensor (calibrated in the range of 0 to 6 bar) and connected to a tube equipped with an inflation valve.
• the permeameter can receive standard specimens in the form of a disc (for example 65 mm diameter in this case) and with a uniform thickness of up to 3 mm (0.5 mm in the present case).
• the pressure sensor is connected to a National Instruments data acquisition card (four-channel analog 0-10V acquisition) which is connected to a computer performing a continuous acquisition with a frequency of 0.5 Hz (1 point every two seconds).
• the coefficient of permeability (K) is measured from the linear regression line giving the slope a of the loss of pressure through the test piece as a function of time, after stabilization of the system that is to say obtaining a stable regime in which the pressure decreases linearly with time.
• Gas-tight compositions containing the components shown in Table I below were prepared conventionally, for example, by incorporating the various components into a twin-screw extruder, so as to achieve matrix fusion and incorporation. all ingredients, then use a flat die to make the profile, deposited on a spacer.
• the tightness, represented by the coefficient of permeability (K), was measured on specimens according to the procedure described above.
• compositions 1-2, 1-3 and 1-4 are in accordance with the invention.
• composition 1-1 elastomer TPE alone (composition 1-1), used without lamellar filler or extension oil, already has a very good seal.
• Example II The compositions of Example II, comprising the components shown in Table II were prepared in the same manner as those of Example I, optionally additionally using a SYA41R-YAMAGUCHI lamellar filler. Only the composition II-3 is therefore in accordance with the invention. Table II
• formulations II-1 and II-2 show the contribution that the charges represent on the seal.
• Formula II-3 demonstrates that the charge and high resin effect Tg accumulates, leading to excellent sealing performance.

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