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
  • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
  • B29D30/00—Producing pneumatic or solid tyres or parts thereof
  • B29D30/06—Pneumatic tyres or parts thereof (e.g. produced by casting, moulding, compression moulding, injection moulding, centrifugal casting)
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
  • B29D30/00—Producing pneumatic or solid tyres or parts thereof
  • B29D30/06—Pneumatic tyres or parts thereof (e.g. produced by casting, moulding, compression moulding, injection moulding, centrifugal casting)
  • B29D30/0681—Parts of pneumatic tyres; accessories, auxiliary operations
• • 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
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
  • B29D30/00—Producing pneumatic or solid tyres or parts thereof
  • B29D30/06—Pneumatic tyres or parts thereof (e.g. produced by casting, moulding, compression moulding, injection moulding, centrifugal casting)
  • B29D30/0681—Parts of pneumatic tyres; accessories, auxiliary operations
  • B29D2030/0682—Inner liners
• • 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
  • B60C2005/145—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 made of laminated layers

Definitions

• the present invention relates to pneumatic tires, and more particularly it relates to gastight layers ensuring the tightness of these tires.
• the radially inner face has an airtight layer (or more generally any inflation gas) which allows inflation and pressure maintenance 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 materials of the internal structure of the tire from the diffusion of air from the interior space to the bandage.
• inner liner This inner layer function or "inner liner” (“inner liner”) waterproof is now fulfilled by compositions based on butyl rubber (isobutylene copolymer and isoprene), recognized for a long time for their excellent sealing properties.
• WO 2008/145277 of the Applicants discloses a pneumatic object provided with a gas-tight layer for inflation, wherein the layer waterproof comprises an elastomeric composition comprising at least one thermoplastic elastomer with polystyrene and polyisobutylene blocks and a polybutene oil.
• thermoplastic elastomer Compared to a butyl rubber, the thermoplastic elastomer has the major advantages, because of its thermoplastic nature, to be worked as is in the molten state (liquid) and therefore to offer a possibility of implementation. simplified design, as well as reducing the rolling resistance of the tire. On the other hand, the use of these gastight layers is limited by the absence of bonds created during the vulcanization of the tire with the adjacent rubber compounds. To solve this problem, the document WO 2010/063427 A1 discloses a tire having a crown with an outer rubbery tread and a crown reinforcement, a carcass reinforcement, a gas-tight layer disposed internally relative to the reinforcement.
• this deformable assembly of fibers when it is arranged raw between the sealed layer and for example the calendering of the carcass reinforcement ensures, after cooking at high temperature and under pressure, a good adhesion of the sealing layer on the calender of the tire.
• This deformable assembly of fibers further has the advantage of substantially improving the sealing performance of the tire.
• the gas-tight layer may be based on a butyl rubber.
• the invention also relates to a method of manufacturing a tire having a gas-tight layer, wherein is incorporated in said tire during manufacture an adhesion layer, characterized in that it has on the radially outer surface of said gas-tight layer an adhesion layer consisting of a deformable assembly of fibers.
• the invention particularly relates to pneumatic tires intended to equip tourism-type motor vehicles, SUV ("Sport Utility Vehicles"), two wheels (including motorcycles), aircraft, such as industrial vehicles selected from vans, "heavy goods vehicles” - that is, metro, buses, road transport vehicles (trucks, tractors, trailers), off-the-road vehicles such as agricultural or civil engineering vehicles -, other vehicles transportation or handling.
• SUV Sport Utility Vehicles
• aircraft such as industrial vehicles selected from vans, "heavy goods vehicles” - that is, metro, buses, road transport vehicles (trucks, tractors, trailers), off-the-road vehicles such as agricultural or civil engineering vehicles -, other vehicles transportation or handling.
• 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 (that is to say terminals a and b excluded). ) while any range of values designated by the expression “from a to b” signifies the range of values from a to b (that is to say, including the strict limits a and b).
• butyl rubber copolymers of isobutylene and styrene derivatives such as copolymers of isobutylene and brominated methylstyrene (BIMS) including elastomer part63 named "EXXPRO” marketed by Exxon.
• BIMS brominated methylstyrene
• the adhesion layer according to an object of the invention is used to enhance the adhesion to the rest of the tire structure of all the waterproof layers based on butyl rubber, that this rubber is the only elastomer of the watertight layer or ⁇ majority elastomer thereof.
• TPEI thermoplastic elastomer with polyisobutylene block
• Polyisobutylene block thermoplastic elastomers have an intermediate structure between thermoplastic polymers and elastomers. They consist of rigid thermoplastic blocks connected by flexible polyisobutylene elastomer blocks. These TPEI may be for example diblock copolymers, comprising a thermoplastic block and an elastomer block, here 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. Typically, each of these segments or blocks contains at least more than 5, usually more than 10 base units.
• a value within a range of 50,000 to 300,000 g / mol is particularly well suited, especially to a use of the polyisobutylene block thermoplastic elastomer or TPEI in a tire composition.
• the number average molecular weight (Mn) of the TPEI is determined in a 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 elastomeric block is composed mainly of polymerized isobutylene monomer.
• the block copolymer polyisobutylene block has a number-average molecular weight ("Mn") ranging from 25,000 g / mol to 350,000 g / mol, preferably 35,000 g / mol to 250,000 g / mol of in order to give the thermoplastic elastomer good elastomeric properties and sufficient mechanical strength and compatible with the internal rubber application of a tire.
• the polyisobutylene block of the block copolymer further has a glass transition temperature ("Tg") less than or equal to -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 waterproof layer during use at very low temperatures; for such use, the Tg of the polyisobutylene block copolymer block is more preferably still lower than -50 ° C.
• the polyisobutylene block of the TPEI may also advantageously also comprise a level of units originating from one or more conjugated dienes inserted into the polymeric chain preferably ranging up to 16% by weight relative to the weight of the polyisobutylene block. Above 16%>, a decrease in the resistance to thermooxidation and ozone oxidation of the sealing layer containing the polyisobutylene block thermoplastic elastomer used in a tire can be observed.
• Conjugated dienes that can be copolymerized with isobutylene to form the polyisobutylene block are C 4 -C 14 conjugated dienes.
• these conjugated dienes are chosen from isoprene, butadiene, 1-methylbutadiene,
• the conjugated diene is isoprene or a mixture containing isoprene.
• the polyisobutylene block may be halogenated and include halogen atoms in its chain.
• This halogenation makes it possible to improve the compatibility of the sealing layer with the other adjacent elements constituting a tire.
• Halogenation is by means of bromine or chlorine, preferably bromine, on the units derived from conjugated dienes of the polyisobutylene block polymer chain. Only a part of these units reacts with halogen.
• the glass transition temperature characteristic (Tg) of the thermoplastic rigid block will be used. This characteristic is well known to those skilled in the art. It allows in particular to choose the temperature of industrial implementation (transformation). In the case of an amorphous polymer (or a polymer block), the processing temperature is chosen to be substantially greater than the Tg of the thermoplastic block. In the specific case of a semi-crystalline polymer (or a polymer block), a melting point can be observed, then greater than the glass transition temperature. In this case, it is rather the melting temperature (Tf) which makes it possible to choose the temperature of implementation of the polymer (or block of polymer) considered. Thus, later, when we talk about "Tg (or Tf, if any)", we must consider that this is the temperature used to choose the temperature of implementation.
• bromostyrenes for example ⁇ -bromostyrene, m-bromostyrene, p-bromostyrene, 2,4-dibromostyrene, 2,6-dibromostyrene or 2,4,6-tribromostyrene
• fluoro styrenes for example ⁇ -fluorostyrene, m-fluorostyrene, p-fluorostyrene, 2,4-difluorostyrene, 2,6-difluorostyrene or 2,4,6-trifluorostyrene
• para-hydroxy-styrene for example ⁇ -fluorostyrene, m-fluorostyrene, p-fluorostyrene, 2,4-difluorostyrene, 2,6-difluorostyrene or 2,4,6-trifluorostyrene
• thermoplastic elastomer TPSI is polystyrene blocks and polyisobutylene.
• TPSI is a diblock styrene / isobutylene elastomer (abbreviated "SIB").
• SIB diblock styrene / isobutylene elastomer
• TPSI is a triblock styrene / isobutylene / styrene elastomer (abbreviated as "SIBS").
• the weight content of styrene (unsubstituted or substituted) in the styrenic elastomer 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%.
• the TPSI elastomers can be implemented in a conventional manner, by extrusion or molding, for example from a raw material available in the form of beads or granules.
• the TPEI elastomers may also comprise a thermoplastic block having a Tg (or Tf, where appropriate) greater than or equal to 100 ° C. and consisting of polymerized monomers other than styrenic monomers ( abbreviated "TPNSI").
• Tg or Tf, where appropriate
• TPNSI polymerized monomers other than styrenic monomers
• 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 will for example be able to refer to the patent document US4946899, by the inventors Kennedy, Puskas, Kaszas and Hager and to 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;
• this other monomer capable of copolymerizing with the polymerized monomer other than a styrenic monomer may be chosen from diene monomers, more particularly conjugated diene monomers having 4 to 14 carbon atoms, and vinylaromatic type monomers having from 8 to 20 carbon atoms.
• the comonomer is a conjugated diene having 4 to 14 carbon atoms
• conjugated dienes that can be used in the thermoplastic blocks according to one object of the invention are those described above, namely isoprene, butadiene, 1-methylbutadiene, 2-methylbutadiene and 2,3-dimethyl-1.
• the comonomer is of the 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 preferentially ranging from 0 to 50%.
• vinylaromatic compounds are particularly suitable styrenic monomers mentioned above, namely methylstyrenes, para-tert-butylstyrene, chlorostyrenes, bromostyrenes, fluoro styrenes 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 derivatives styrene, especially para-methylstyrene or para-tertiobutyl styrene.
• indene and derivatives styrene especially para-methylstyrene or para-tertiobutyl styrene.
• Those skilled in the art can then refer to the documents JE Puskas, G. Kaszas, JP Kennedy, WG Hager, Journal of Polymer Science part A: Polymer Chemistry 1992 30, 41 or JP Kennedy, S. Midha, Y. Tsungae Macromolecules (1993) 26, 429.
• an elastomer composition comprising one or more polyisobutylene block thermoplastic elastomers as previously described.
• the major component of this composition is preferably this or these TPEI, that is to say that the composition comprises more than 50 phr (parts per hundred parts of elastomer) of this or these TPEI.
• the gas-tight layer described above could optionally comprise other elastomers than the TPEI, preferably in a minor amount (less than 50 phr).
• Such complementary elastomers could be, for example, diene elastomers such as natural rubber or synthetic polyisoprene, butyl rubber or other saturated thermoplastic styrene elastomers, within the limit of the compatibility of their microstructures.
• the level of TPEI elastomer in the sealed composition is greater than 70 phr, in particular in a range of 80 to 100 phr.
• the or TPEI in particular SIB or SIBS
• the above described TPEI, in particular SIB or SIBS, is sufficient on its own to fill, in the elastomer layer, the gas-tight function with respect to the pneumatic tires in which they are used.
• this TPEI may be associated, as plasticizer, with an extender oil (or plasticizing oil) whose function is to facilitate the implementation, particularly the integration into a pneumatic object by a lowering of the module and an increase in the tackifiant power of the gas-tight layer.
• an extender oil or plasticizing oil
• extension oil preferably of a slightly polar nature, capable of extending and plasticizing elastomers, especially thermoplastics, may be used.
• these oils are liquids (that is to say, as a reminder, substances having the ability to eventually take the form of their container) , in contrast 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), paraffmic oils and naphthenic oils. (low or high viscosity), aromatic oils, mineral oils and mixtures of these oils.
• Polybutene oils particularly polyisobutylene oils (abbreviated as "PIB"), which have demonstrated the best compromise of properties compared to other oils tested, especially oils of the paraffmic type.
• PIB polyisobutylene oils
• polyisobutylene oils are sold in particular by the company UNIVAR under the name "Dynapak Poly” (eg "Dynapak Poly 190"), by BASF under the names “Glissopal” (eg “Glissopal 1000") or "Oppanol” (eg "Oppanol B12”), by INEOS Oligomer under the name "Indopol H1200”.
• Paraffmic 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 number-average molecular mass (Mn) of the extender 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 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 greater than 10 phr, in particular between 10 and 90 phr, more preferably still than it is greater than 20 phr, in particular between 20 and 80 phr.
• the gas-tight layer may also comprise lamellar fillers.
• lamellar filler advantageously makes it possible to lower the coefficient of permeability (thus increasing the seal) of the elastomer composition, without excessively increasing its modulus, which makes it possible to maintain the ease of integration. of the sealing layer in the pneumatic object.
• platy fillers are well known to the skilled person. 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). They have also been used in tight layers based on TPEI, see WO 2009/007064 and WO 2011/012529.
• L L / E
• E the average thickness of these lamellar fillers, these averages being calculated in number. Reports of form reaching several tens or even hundreds are frequent.
• Their average length is preferably greater than 1 ⁇ (that is to say that it is then said micrometric 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 low surface energy that is to say relatively apolar, such as those chosen from the group consisting of graphites, talcs, micas and mixtures of such fillers.
• the latter may or may not be modified, more preferably still in the group consisting of graphites, talcs and mixtures of such fillers.
• the graphites can be mentioned including natural graphites, expanded graphites or synthetic graphites.
• micas examples include micas marketed by the company CMMP (Mica-MU®, Mica-Soft®, Briomica® for example), those sold by the company YAMAGUCHI (A51S, A41S, SYA-21R, SYA-21RS, A21S, SYA-41R), vermiculites (in particular Shawatec® vermiculite marketed by CMMP or vermiculite Microlite® marketed by WR Grace), modified or treated micas (for example, the Iriodin® range marketed by Merck) .
• graphites mention may be made of graphites marketed by Timcal (Timrex® range).
• talcs mention may be made of talcs marketed by Luzenac.
• the waterproof layer may also comprise various additives, especially those usually present in airtight layers and / or adhesive layers known to those skilled in the art, for example reinforcing fillers such as carbon black or silica, non-reinforcing or inert fillers, plasticizers other than those mentioned above, protective agents such as antioxidants or antiozonants, anti-UV agents, coloring agents that can advantageously be used for coloring the compositions, various agents for implementing or other stabilizers.
• additives especially those usually present in airtight layers and / or adhesive layers known to those skilled in the art, for example reinforcing fillers such as carbon black or silica, non-reinforcing or inert fillers, plasticizers other than those mentioned above, protective agents such as antioxidants or antiozonants, anti-UV agents, coloring agents that can advantageously be used for coloring the compositions, various agents for implementing or other stabilizers.
• the airtight layer described is a solid compound (at 23 ° C) and elastic, which is characterized in particular, thanks to its specific formulation, by a very high flexibility and very high deformability.
• the sealed layer 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); 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.
• the airtight layer described above has a thickness greater than 0.05 mm, more preferably between 0.1 and 10 mm (for example from 0.2 to 2 mm).
• the embodiment of the invention may vary, the first airtight layer comprising in fact several ranges. preferential thickness.
• the first airtight layer comprising in fact several ranges. preferential thickness.
• passenger-type tires they may have a thickness of at least 0.3 mm, preferably between 0.5 and 2 mm.
• the preferred thickness may be between 1 and 3 mm.
• the preferred thickness may be between 2 and 10 mm. 1-2.
• An essential element of the adhesion layer according to one aspect of the invention is to consist of a deformable assembly of fibers.
• fiber assembly any manufactured product consisting of a web, a web or a mat of fibers, whether distributed directionally or by chance, and whose fibers are entangled or interlocking two-dimensionally or three-dimensionally for the non-woven or woven for the woven.
• webs or mattresses of fibers made by short fiber projection, for example.
• deformable assembly of fibers any assembly of fibers in which the fibers can easily slide relative to each other and therefore which supports a significant deformation without tearing and opposing only a weak resistance in at least one direction.
• the fibers may be filaments, monofilaments or multifilament assemblies.
• this deformable assembly of fibers, woven or non-woven allows to create during the baking of the tire a substantial adhesion between the gas-tight layer and the adjacent rubber mix by impregnating the deformable assembly of fibers by these two compositions made during cooking under high pressure and at high temperature.
• the assembly of fibers must be put in place during the manufacture of the tire so that the deformability of the assembly in the circumferential direction is sufficient to allow the conformation but also the rolling deformations of the tire. pneumatic tire.
• the deformable assembly of fibers is non-woven or non-woven.
• the fibers of such a non-woven or non-woven assembly must not be rigidly bonded to each other to give the fiber assembly the ability to follow the conformation of the tire during its manufacture.
• the non-woven according to an object of the invention do not comprise adhesion or bonding product usually intended to consolidate the nonwoven web or mattress.
• nonwoven assembly An example of such a nonwoven assembly is marketed by the company PGI with reference NLC 10-501.
• the fibers are polyester and the nonwoven has a thickness of 0.3 mm and a basis weight of 50 g / m 2 .
• the extensibility of such fabrics allows the assembly to follow the conformation of the tire during its manufacture.
• This extensibility can be related to the fiber assembly technique, for example by knitting, or to the embodiment of the fibers themselves to make them elastic.
• An example of elastic fabric is the knit sold by Milliken under the reference 2700 composed of 82% of polyamide 6 fibers and 18% of polyurethane 44 dTex.
• the deformable assembly of fibers is a two-dimensional mat of short fibers, obtained for example by the projection of short fibers, that is to say fibers whose length is between a few millimeters and a few centimeters.
• the fibers are not bonded together and such an assembly exerts virtually no return force in case of deformation.
• the ratio between the length and the diameter of the fibers of the deformable assembly is greater than 20 and very preferably greater than 50, or even greater than 100.
• the fibers of the deformable assembly of fibers may be chosen from naturally occurring textile fibers, for example, in the group of silk fibers, cotton fibers, bamboo fibers, cellulose fibers, wool fibers and their blends. .
• assemblies of wool fibers are the felts "PLB” and "MLB” of the company Laoureux.
• the fibers of the deformable assembly of fibers may also be chosen from the group of synthetic textile fibers, for example polyester, polyamide, carbon, aramid, polyethylene, polypropylene, polyacrylonitrile, polyimide polysulfones, polyether sulfones, polyurethanes, polyvinyl alcohol and mixtures thereof.
• the fiber assemblies may be indifferently composed of several types of fibers of the same group or of different groups as previously described.
• the weight per unit area or basis weight of the deformable assembly of fibers before impregnation of an elastomeric material is greater than 1 g / m 2 , more preferably greater than 10 g / m 2 and even more preferentially between 20 and 120 g / m 2 .
• Such a low basis weight of the deformable assembly of fibers provides excellent impregnation by the adjacent elastomeric materials under pressure and hot.
• the thickness of the deformable assembly of fibers prior to its impregnation is less than 1 millimeter, preferably less than 500 micrometers and very preferably less than 200 micrometers. This facilitates good impregnation of the fibers by the adjacent elastomers. This impregnation is carried out during the vulcanization of the tire at a temperature above 150 ° C. and at a pressure greater than 10 bar. This ensures excellent impregnation of adjacent elastomeric materials without leaving voids.
• the gas-tight layer with adhesion layer according to an object of the invention is advantageously usable in pneumatic tires of all types of vehicles, in particular in passenger car tires. to ride at very high speeds or tires for industrial vehicles such as heavy goods vehicles.
• the single appended figure shows very schematically (without respecting a specific scale), a radial section of a tire according to the invention for a tourism type vehicle.
• This figure 1 comprises an orthogonal reference, Y corresponds to the axial direction, with reference to the axis of rotation of the tire, ⁇ ', Z corresponds to the radial direction, of the axis of rotation to the apex of the tire.
• pneumatic tire and X corresponds to the longitudinal or circumferential direction. At all points, X is normal to the Y and Z directions.
• This tire 1 has a top 2 reinforced by a crown reinforcement or belt 6, two sides 3 and two beads 4, each of these beads 4 being reinforced with a rod 5.
• the top 2 is surmounted by a band bearing not shown in this schematic figure.
• An armature or reinforcement of carcass 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 armature of carcass 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 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 situated halfway between the two beads 4 and goes through the middle of the crown frame 6).
• radial cables for example textile or metal
• the two layers (10a, 10b) substantially cover the entire inner wall of the tire, extending from one flank to the other, at least up to the level of the tire hook. rim when the tire is in the mounted position.
• the layer 10a (approximately 0.75 mm thick) comprises an SIBS elastomer ("Sibstar 102T" with a styrene content of about 15%, a Tg of about -65 ° C.
• the adhesion layer 10b was itself a deformable assembly of fibers consisting of a nonwoven or nonwoven polyester fabric 0.3 mm thick and 50 g / m 2 NLC reference weight 10- 501 marketed by the company PGI.
• Such a two-layer laminate as described above can easily be made by extrusion of the gas-tight layer directly on the deformable assembly of fibers. This results in partial impregnation of the deformable assembly of fibers by the gas-tight layer. The laminate is then used as semi-finished during the production of the tire.
• the coefficient of permeability (K) is measured from the linear regression line (average over 1000 points) giving the slope a of the loss of pressure, through the tested 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.
• Adhesion tests were also conducted to test the ability of the gas-tight layer to adhere after firing to a diene elastomer layer, more specifically to a conventional rubber composition for reinforcement. of tire carcass, based on natural rubber (peptized) and N330 carbon black (65 parts by weight per hundred parts of natural rubber), further comprising the usual additives (sulfur, accelerator, ZnO, stearic acid, antioxidant ).
• the peel test pieces (of the 180 ° peel type) were made by stacking a thin layer of gas-tight composition with and without a deformable assembly of fibers between two calendered fabrics the first with a SIBS elastomer (1). , 5 mm) and the other with the diene mixture in question (1.2 mm). A rupture primer is inserted between the two calendered fabrics at the end of the thin layer.
• test piece after assembly was vulcanized at 180 ° C. under a pressure of 15 bar for 10 minutes. These conditions are representative of the firing of a tire. Strips 30 mm wide were cut with a cutter. Both sides of the breakout primer were then placed into the jaws of an Instron ® brand traction machine. The tests are carried out at ambient temperature and at a tensile speed of 100 mm / min. The tensile forces are recorded and these are standardized by the width of the specimen. A force curve is obtained per unit of width (in N / mm) as a function of the displacement of the moving beam of the traction machine (between 0 and 200 mm). The value of adhesion retained corresponds to the initiation of the rupture within the specimen and therefore to the maximum value of this curve.
• Table 1 gives the results of the tests by taking the value 100 for the test pieces E-1.
• the use of the adhesive layer based on a deformable assembly of fibers makes it possible to improve strongly, by a factor greater than five, or even more in many cases, the adhesion between the layer. gas tight and natural rubber composition.

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• 2012
  • 2012-11-15 FR FR1260868A patent/FR2997893B1/fr active Active
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  • 2013-11-07 WO PCT/EP2013/073235 patent/WO2014075985A1/fr not_active Ceased
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  • 2013-11-07 US US14/443,254 patent/US20150290975A1/en not_active Abandoned
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