Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C73/00—Repairing of articles made from plastics or substances in a plastic state, e.g. of articles shaped or produced by using techniques covered by this subclass or subclass B29D
  • B29C73/16—Auto-repairing or self-sealing arrangements or agents
  • B29C73/163—Sealing compositions or agents, e.g. combined with propellant agents
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C73/00—Repairing of articles made from plastics or substances in a plastic state, e.g. of articles shaped or produced by using techniques covered by this subclass or subclass B29D
  • B29C73/16—Auto-repairing or self-sealing arrangements or agents
  • B29C73/22—Auto-repairing or self-sealing arrangements or agents the article containing elements including a sealing composition, e.g. powder being liberated when the article is damaged
• • 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
  • B60C19/00—Tyre parts or constructions not otherwise provided for
  • B60C19/12—Puncture preventing arrangements
  • B60C19/122—Puncture preventing arrangements disposed inside of the inner liner
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
  • B29L2030/00—Pneumatic or solid tyres or parts thereof
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T152/00—Resilient tires and wheels
  • Y10T152/10—Tires, resilient
  • Y10T152/10495—Pneumatic tire or inner tube
  • Y10T152/10666—Automatic sealing of punctures [e.g., self-healing, etc.]

Definitions

• the present invention relates to "pneumatic" objects, i.e., by definition, objects that take their usable form when inflated with air or an equivalent inflation gas.
• Self-sealing compositions useful as puncture-resistant layers in pneumatic tires are well known. By definition able to ensure automatically, that is to say without any external intervention, the sealing of a tire in case of perforation of the latter by a foreign body such as a nail, these compositions are particularly difficult to to develop.
• the self-sealing layers must indeed satisfy many conditions of a physical and chemical nature, be effective in a very wide range of operating temperatures and throughout the life of the tires. They must be capable of closing the hole when the piercing object remains in place; the expulsion of the latter, they must be able to fill the hole and make the bandage waterproof, especially in winter conditions.
• the self-sealing compositions which have hitherto been used in pneumatic tires are essentially based on butyl rubber (isobutylene and isoprene copolymer).
• the radially inner face has an airtight layer (or more generally any gas) inflation) which allows inflation and pressure maintenance of the tire.
• airtight layer or more generally any 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 from the diffusion of air from the interior space to the bandage.
• inner layer or “inner liner” waterproof inner liner
• compositions which are also based on butyl rubber, recognized for a long time for their excellent sealing properties.
• a well known disadvantage of butyl rubber-based compositions is that they have significant hysteretic losses, moreover over a wide temperature spectrum, a disadvantage that penalizes the rolling resistance of pneumatic tires.
• Patent application WO 2008/080557 has proposed the use in a pneumatic tire of a self-sealing layer totally free of butyl rubber, and thus already partly meeting the above objective of hysteresis reduction.
• This self-sealing layer has the characteristic of comprising, as a majority elastomer, a styrenic thermoplastic elastomer and an extension oil at a particularly high level, of between 200 and 700 phr, said TPS elastomer being particularly selected from the group. consisting of SEBS copolymers, SEPS copolymers and mixtures of these copolymers.
• the above self-sealing layer is associated with a second gas-tight layer to form a particularly effective airtight and puncture-resistant bilayer laminate.
• the gas-tight layer remains based on butyl rubber, therefore relatively hysteretic.
• the present invention relates to a pneumatic object provided with a self-sealing elastomeric layer and impervious to inflation gases, characterized in that said elastomer layer comprises at least, as majority elastomer, a copolymer thermoplastic block polystyrene and polyisobutylene, and at least 100 phr of an extension oil.
• the invention particularly relates to pneumatic objects of rubber such as pneumatic tires, or inner tubes, in particular tubes for pneumatic tires.
• the invention relates more particularly to pneumatic tires intended to equip tourism-type motor vehicles, SUVs ("Sport Utility Vehicles"), two wheels (in particular motorcycles), planes, such as industrial vehicles such as vans, heavy goods vehicles (that is, metros, buses, road transport vehicles such as trucks, tractors, trailers, off-the-road vehicles such as agricultural or civil engineering vehicles) and other transport or handling vehicles.
• SUVs Sport Utility Vehicles
• two wheels in particular motorcycles
• planes such as industrial vehicles such as vans, heavy goods vehicles (that is, metros, buses, road transport vehicles such as trucks, tractors, trailers, off-the-road vehicles such as agricultural or civil engineering vehicles) and other transport or handling vehicles.
• the invention also relates to the use of a thermoplastic block copolymer with polystyrene and polyisobutylene blocks and at least 100 phr of an extension oil as a self-sealing and airtightness-proof layer in a pneumatic object.
• 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 of the invention has the essential feature of being provided with a self-sealing and gas-tight layer formed of an elastomer composition (or "rubber", both being considered in a known manner as synonyms ) of the thermoplastic type, said layer or composition comprising at least, as a majority elastomer, a thermoplastic copolymer with polystyrene and polyisobutylene blocks, and an extender oil at a weight ratio of at least 100 phr.
• thermoplastic styrene elastomers are thermoplastic elastomers in the form of block copolymers based on styrene.
• TPS thermoplastic styrene elastomers
• rigid polystyrene blocks connected by flexible elastomer blocks, for example polybutadiene, polyisoprene or poly (ethylene / butylene).
• flexible elastomer blocks for example polybutadiene, polyisoprene or poly (ethylene / butylene). 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.
• TPS elastomers may also be diblock elastomers with a single rigid segment connected to a flexible segment.
• each of these segments or blocks contains at least more than 5, usually more than 10 base units (e.g., styrene units and isoprene units for a styrene / isoprene / styrene block copolymer).
• polystyrene and polyisobutylene block copolymer is intended to mean any styrenic thermoplastic copolymer comprising at least one polystyrene block (that is to say one or more polystyrene blocks) and at least one polyisobutylene block. (ie one or more polyisobutylene blocks), to which other saturated or unsaturated blocks (e.g. polyethylene and / or polypropylene) and / or other monomer units (e.g. unsaturated dienes).
• This specific copolymer with polystyrene and polyisobutylene blocks is in particular chosen from the group consisting of styrene / isobutylene diblock copolymers (abbreviated as "SIB”), styrene / isobutylene / triblock copolymers. styrene (abbreviated as "SIBS”) and mixtures of these copolymers SBIB and SIBS, by definition totally saturated.
• SIBS styrene
• the invention is also applicable to cases where the polyisobutylene block, in the above copolymers, can be interrupted by one or more unsaturated units, in particular one or more diene units such as isoprenic, optionally halogenated.
• TPS copolymer in particular SIB or SIBS, provides the self-sealing and gastight layer with excellent sealing properties while significantly reducing hysteresis compared to conventional layers. based on butyl rubber.
• the weight content of styrene in the TPS copolymer is between 5% and 50%.
• the thermoplastic nature of the elastomer may decrease significantly while above the maximum recommended, the elasticity of the seal layer may be affected.
• the styrene content is more preferably between 10% and 40%, in particular between 15 and 35%.
• styrene must be understood in the present description any monomer based styrene, whether unsubstituted as substituted; among the substituted styrenes may be mentioned, for example, methylstyrenes (for example ⁇ -methylstyrene, ⁇ -methylstyrene, p-methylstyrene, tert-butylstyrene) and chlorostyrenes (for example monochlorostyrene, dichlorostyrene).
• methylstyrenes for example ⁇ -methylstyrene, ⁇ -methylstyrene, p-methylstyrene, tert-butylstyrene
• chlorostyrenes for example monochlorostyrene, dichlorostyrene
• the glass transition temperature (Tg, measured according to ASTM D3418) of the TPS copolymer is less than -20 ° C, more preferably less than -40 ° C.
• Tg glass transition temperature
• a value of Tg higher than these minima can reduce the performance of the gas-tight and self-sealing layer when used at very low temperatures; for such use, the Tg of the TPS copolymer is more preferably still lower than -50 ° C.
• the number-average molecular weight (denoted Mn) of the TPS 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 cohesion between the chains of the elastomer especially due to the possible dilution of the latter by an extension oil, may be affected.
• a mass Mn that is too high can be detrimental to the flexibility of the gas-tight layer.
• a value within a range of 50,000 to 300,000 g / mol is particularly well suited, in particular to a use of the composition in a tire.
• the number-average molecular weight (Mn) of the TPS copolymer 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 a 0.45 ⁇ m porosity filter before injection.
• the equipment used is a chromatographic chain "WATERS alliance”.
• 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 ⁇ 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.
• the TPS copolymer and the extension oil associated with it may alone constitute the gas-tight and self-sealing elastomeric layer, or in the elastomeric composition, be associated with other elastomers in a minor amount relative to the TPS copolymer.
• the TPS copolymer constitutes the majority elastomer by weight. Its rate is then preferentially greater than
• phr means parts by weight per hundred parts of total elastomer, that is to say the total of elastomers present in the composition forming the layer gas tight).
• 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.
• Such complementary elastomers which are minor in weight, could also be other styrenic thermoplastic elastomers, whether of the unsaturated type as saturated (that is to say in known manner, provided or not with ethylenic unsaturations or double bonds carbon-carbon).
• unsaturated TPS elastomers there may be mentioned, for example, those comprising styrene blocks and diene blocks, in particular those chosen from the group consisting of styrene / butadiene block copolymers (SB) and styrene / isoprene block copolymers (IS).
• SB styrene / butadiene block copolymers
• IS styrene / isoprene block copolymers
• saturated TPS elastomers mention may be made, for example, of those selected from the group consisting of styrene / ethylene / butylene (SEB), styrene / ethylene / propylene (SEP), styrene / ethylene / ethylene / block copolymers.
• propylene (SEEP) styrene / ethylene / butylene / styrene (SEBS), styrene / ethylene / propylene / styrene (SEPS), styrene / ethylene / ethylene / propylene / styrene (SEEPS) and mixtures of these copolymers.
• the gas-tight and self-sealing layer is devoid of such complementary elastomers; in other words, the TPS copolymer, in particular SIB or SIBS, previously described is the only thermoplastic elastomer and more generally the only elastomer present in the elastomeric composition of the gas-tight layer.
• the polystyrene and polyisobutylene block copolymers are commercially available, they can be implemented conventionally for TPS elastomers, by extrusion or molding, for example from a raw material available in the form of beads or of granules. They are sold, for example, with respect to SIBs or SIBS by KANEKA under the name "SIBSTAR" (eg "Sibstar 103T", “Sibstar 102T", “Sibstar 073T” or “Sibstar 072T" for SIBS, "Sibstar 042D "for SIBs). For example, they have been described, as well as their synthesis, in patent documents EP 731 1 12, US 4,946,899 and US 5,260,383.
• TPE elastomers were first developed for biomedical applications and then described in various applications specific to TPE elastomers, as varied as medical equipment, parts for automobiles or household appliances, sleeves 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). ).
• the second essential constituent of the self-sealing and gas-tight layer is an extender oil (or plasticizing oil), used at a relatively high level, equal to or greater than 100 phr.
• 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 capacity to eventually take on the shape of their container), as opposed to especially to resins that are inherently solid.
• the extender oil is chosen from the group consisting of polyolefinic oils (that is to say derived 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. More preferably, the extender oil is selected from the group consisting of polybutene oils, paraffinic oils and mixtures of these oils. Polybutene oils, preferably polyisobutylene oils (abbreviated to "PIB”), which have demonstrated the best compromise of properties compared to the other oils tested, in particular paraffinic oils, are particularly used.
• PIB polyisobutylene oils
• 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 B 12 "), by INEOS Oligomer under the name” Indopol H 1200 ".
• Paraffinic oils are sold 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 molecular weight M n of the extension oil is determined by SEC, the sample being solubilized beforehand in tetrahydrofuran at a concentration of approximately 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 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 ⁇ 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.
• a major and remarkable advantage of the present invention is that the adjustment in the formulation of the extension oil content, typically in a range from 100 to 700 phr, will advantageously allow, according to the particular conditions of use which are aimed at, of rather, favor the sealing properties (with a lower rate of extension oil) or rather those of self-sealing (with a higher rate of extension oil).
• the level of extender oil in particular of polybutene oil, is at least equal to 120 phr, in particular between 120 and 700 phr; more preferably, this level of extender oil is at least equal to 150 phr, in particular within a range of 150 to 500 phr, below the indicated minima, the elastomer layer risks having 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 detrimental to the application in question.
• the gas-tight and self-sealing 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.
• this elastomer layer or composition has a secant modulus in extension, at 10% elongation, which is less than 2 MPa, more preferably less than 1.5 MPa (especially less than 1 MPa). MPa). This quantity is measured at first elongation (ie without accommodation cycle) at a temperature of 23 ° C, with a pulling speed of 500 mm / min (ASTM D412), and reported in section initial test piece.
• TPS copolymer and extension oil are sufficient on their own for the self-sealing gas-tight composition to fully fulfill its sealing and anti-puncture functions vis-à-vis pneumatic objects. in which it is used.
• additives may be added, such as, for example, reinforcing fillers such as carbon black or silica, non-reinforcing or inert fillers, lamellar fillers which further improve the seal (eg phyllosilicates such as kaolin, talc, mica, graphite, clays or clays modified ("organo clays"), plasticizers other than the aforementioned extension oils, for example tackifying resins, protective agents such as antioxidants or antiozonants, anti-UV, coloring agents advantageously used for coloring the composition, various processing agents or other stabilizers, or alternatively promoters capable of promoting adhesion to the rest of the structure of the pneumatic object.
• reinforcing fillers such as carbon black or silica
• non-reinforcing or inert fillers eg.g kaolin, talc, mica, graphite, clays or clays modified (“organo clays")
• plasticizers other than the aforementioned extension oils
• plasticizers other than
• lamellar fillers advantageously makes it possible to further reduce the coefficient of permeability (and therefore to increase the seal) of the thermoplastic elastomer composition, without excessively increasing its modulus, which makes it possible to maintain the ease of integration of the waterproof layer in the pneumatic object.
• Such fillers are generally in the form of plates, platelets, sheets or stacked sheets, with a more or less marked anisometry, whose average length is for example between a few microns and a few hundred microns. They can be used at variable weight rates depending on the application, for example between 20 and 150 phr.
• this sealed composition could also comprise, still in a minority weight fraction relative to the TPS copolymer, polymers other than elastomers, such as, for example, thermoplastic polymers compatible with TPS elastomers.
• composition described above can be used as an airtight and self-sealing layer in any type of pneumatic object.
• pneumatic objects include pneumatic boats, balls or balls used for play or sport.
• Such a self-sealing and gas-tight layer is preferably disposed on the inner wall of the pneumatic object, but it can also be completely integrated into its internal structure.
• the thickness of this layer is preferably greater than 0.2 mm, more preferably between 0.3 and 30 mm, especially between 0.5 and 20 mm.
• the passenger car or two-wheel type may have a thickness of at least 0.5 mm, preferably between 1 and 4 mm.
• the preferential thickness may be between 2 and 20 mm.
• the preferred thickness can be between 4 and 30 mm.
• the air-tight and self-sealing composition described above has the advantage of having a much lower hysteresis, and thus of offering reduced rolling resistance to bandages. as shown in the following exemplary embodiments.
• the self-sealing elastomeric layer and gas-tight inflation described above can be used advantageously in tires of all types of vehicles, especially passenger vehicles or industrial vehicles such as trucks.
• the single appended figure shows very schematically (without respecting a specific scale), a radial section of a tire according to the invention, intended for example for a passenger vehicle.
• 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 a self-sealing layer 10 and airtight, for example with a thickness of about 4 mm, on the side of the inner cavity 1 1 of the tire 1.
• This inner layer (or “inner liner”) covers the entire inner wall of the tire, extending from one side to the other, at least as far as the hooking hook when the tire is in the mounted position.
• the above layer 10 is a layer of SIBS thermoplastic elastomer ("Sibstar 102T" with a styrene content of about 15%, a Tg of about -65 ° C and a mass Mn of about 90,000 g / mol) extended with 150 phr of PIB oil ("Indopol H 1200" with a mass Mn of about 2100 g / mol).
• SIBS thermoplastic elastomer (Sibstar 102T" with a styrene content of about 15%, a Tg of about -65 ° C and a mass Mn of about 90,000 g / mol) extended with 150 phr of PIB oil (“Indopol H 1200" with a mass Mn of about 2100 g / mol).
• the first function of the layer 10 is to provide effective protection against pressure losses due to accidental perforations, allowing the automatic closure of these perforations. If a foreign object such as a nail passes through the structure of the pneumatic object, for example a wall such as a sidewall 3 or the top 6 of the tire 1, the composition serving as a self-sealing layer undergoes several constraints. In response to these constraints, and thanks to its advantageous properties of deformability and elasticity, said composition creates a sealed contact zone all around the body. Regardless of whether the contour or profile of the latter is uniform or regular, the flexibility of the self-sealing composition allows it to interfere in openings of minimal size. This interaction between the self-sealing composition and the foreign body gives a seal to the area affected by the latter.
• a perforation In case of accidental or voluntary removal of the foreign body, a perforation remains: it is likely to create a more or less important leak, depending on its size.
• the self-sealing composition subjected to the effect of hydrostatic pressure, is sufficiently flexible and deformable to seal, by deforming, the perforation, preventing leakage of inflation gas.
• the flexibility of the self-sealing composition makes it possible to easily withstand the forces of the surrounding walls, even during the phases of deformation of the loaded tire and while driving.
• the second function of this same layer 10 is to seal and protect the carcass reinforcement from the diffusion of air from the inner space 11 to the bandage. 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 provided with its self-sealing and airtight elastomeric layer (10) as described above can be produced before or after vulcanization (or baking).
• this elastomer layer is simply applied in a conventional manner to the desired location, for forming the layer 10.
• the vulcanization is then carried out conventionally.
• An advantageous manufacturing variant for those skilled in the tire industry, will consist, for example, in during a first step, depositing the elastomer layer flat on a manufacturing drum in the form of a layer of suitable thickness, before covering the latter with the rest of the tire structure, according to manufacturing techniques well known to those skilled in the art.
• the elastomer layer is applied inside the cooked tire by any appropriate means, for example by gluing, extrusion, spraying or else by extrusion / blowing. a film of appropriate thickness.
• Pneumatic tires according to the invention of the type for a passenger vehicle (dimensions 195/65 Rl 5), have been manufactured; their inner wall was covered by a gas-tight and self-sealing layer (10) with a thickness of 4 mm (on the manufacture drum, before manufacturing the remainder of the tire), then the vulcanized tires.
• Said layer (10) was formed of SIBS extended with 150 phr of PIB oil, as described above.
• a rigid wall permeameter was used, placed in an oven (temperature of 60 ° C in this case), provided with a pressure sensor (calibrated in the range of 0 to 6 bars) 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 (average over 1000 points) giving the slope ⁇ of the pressure loss, through the tested test piece, as a function of time, after stabilization of the system, that is to say obtaining a steady state during which the pressure decreases linearly with time.
• the coefficient of permeability of the SISB layer was significantly less degraded (increased by about 50% instead of 125%) in the presence of a PIB ("Dynapak PoIy 190") oil than a conventional oil such as paraffinic ("Telura 618"). It is in this that the combination of the TPS copolymer such as SIB or SIBS, and PIB oil has been found to offer the best compromise of properties for the self-sealing and gas-tight layer.
• pneumatic tires of the invention were compared to control tires (Michelin brand “Energy 3") comprising a conventional air-tight layer of the same thickness, based on butyl rubber.
• the rolling resistance of pneumatic tires was measured on a steering wheel according to ISO 87-67 (1992).
• an elastomeric composition comprising in combination a polystyrene and polyisobutylene block copolymer and at least 100 phr of an extender oil, has unexpectedly been found not only capable of fulfilling the function of a self-sealing layer as described in particular in the aforementioned application WO 2008/080557, but still and above all suitable for replacing a conventional composition based on butyl rubber as a sealing layer in pneumatic tires, with the key the opportunity to reduce the hysteresis of these bandages sensibly, and therefore the fuel consumption of motor vehicles equipped with such bandages.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Sealing Material Composition (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Tires In General (AREA)

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• 2008
  • 2008-12-03 FR FR0858239A patent/FR2939145B1/fr not_active Expired - Fee Related
• 2009
  • 2009-11-30 JP JP2011538883A patent/JP5452611B2/ja not_active Expired - Fee Related
  • 2009-11-30 CN CN200980148762.3A patent/CN102239046B/zh not_active Expired - Fee Related
  • 2009-11-30 US US13/132,786 patent/US20120118463A1/en not_active Abandoned
  • 2009-11-30 WO PCT/EP2009/008501 patent/WO2010063425A1/fr not_active Ceased
  • 2009-11-30 EP EP09771300A patent/EP2373476B1/fr not_active Not-in-force

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