FR3033571A1 - PNEUMATIC OBJECT COMPRISING AN ELASTOMER LAYER SEALED IN INFLATION GAS BASED ON A CUTTING OF THERMOPLASTIC ELASTOMERS IN THE FORM OF BLOCK COPOLYMERS - Google Patents

Abstract

The invention relates to a pneumatic object provided with an elastomeric layer that is impervious to inflation gases, said elastomer layer predominantly comprising a blend of the following two thermoplastic elastomers: a) a first thermoplastic elastomer in the form of a first block copolymer which comprises a first elastomeric block comprising at least units derived from isobutylene, connected at one of its ends to a first thermoplastic block comprising at least a first block consisting of units derived from at least a first polymerizable monomer and at least a second block consisting of units derived from β-pinene, b) a second thermoplastic elastomer in the form of a second block copolymer which comprises a second elastomeric block comprising at least units derived from isobutylene, connected at each of its two ends to second thermoplastic blocks each comprising at least a first block consisting of units derived from at least one second polymerizable monomer and at least one second block consisting of units derived from β-pinene. The invention also relates to a method for sealing a pneumatic object vis-à-vis the inflation gases.

Description

The present invention relates to "pneumatic" objects, that is to say, by means of a pneumatic filter, which is sealed with inflation gases based on a cutting of thelopoplastic elastomers in the form of block copolymers. definition, to objects that take their usable form when inflated with air or an equivalent inflation gas, and in particular with pneumatic tires. More particularly, the present invention relates to a pneumatic object provided with an elastomeric layer impervious to inflation gases, said elastomer layer comprising predominantly a blend of two thermoplastic elastomers, both being in the form of particular block copolymers. The invention also relates to a method for sealing a pneumatic object by means of the elastomeric layer impervious to inflation gases as defined above. Finally, the invention relates to the use as an airtightness-proof layer, in a pneumatic object, of an elastomeric layer as defined above. In a conventional pneumatic tire of the "tubeless" type (that is to say without a tube), 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. 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. This function of inner layer or rubber "inner" ("inner liner") waterproof is now fulfilled by compositions based on butyl rubber (copolymer of isobutylene and isoprene), 3033571 2 recognized for a long time for their excellent sealing properties. However, a well-known disadvantage of butyl rubber-based compositions is that they exhibit significant hysteretic losses, moreover over a wide range of temperatures, a disadvantage which penalizes the rolling resistance of pneumatic tires. Decreasing the hysteresis of these internal sealing layers and ultimately the fuel consumption of motor vehicles, 10 is a general objective facing current technology. Thermoplastic elastomers of the SIBS (styrene-isobutylene-styrene) type have been developed in order to improve the hysteresis properties of the internal sealing layers containing them. We can notably mention the patent applications FR 08/57844 and FR 08/57845.

However, the use of SIBS based formulations as an internal sealant layer has disadvantages. On the one hand, the SIBS-based internal sealing layers have a lack of adhesion to the other components of the pneumatic object, both as raw material during the constitution of the tire 20 and when cooked with the carcass ply. Indeed, the absence of double bonds in the thermoplastic elastomer makes it insensitive to co-vulcanization with the carcass ply during cooking. On the other hand, pneumatic objects obtained from these thermoplastic elastomers have a limited thermal resistance, which is expressed by the impossibility of removing the pneumatic object from the hot baking press without tearing material but also by the appearance of material creep during thermomechanically demanding endurance tests, such as high speed running tests.

There is therefore a need to develop new pneumatic objects based on a thermoplastic elastomer that can be used as an internal sealing layer. These pneumatic objects, while maintaining good sealing properties, must also have a good compromise in terms of adhesion and in terms of thermal resistance. The Applicant has now surprisingly found that a blend of two thermoplastic elastomers, both being in the form of block copolymers, with a first block copolymer which comprises a first elastomeric block having at least units derived from isobutylene connected at one of its ends to a first thermoplastic block comprising at least a first block consisting of units derived from at least a first polymerizable monomer and at least a second block consisting of units derived from 13-pinene, and a second block copolymer which comprises a second elastomeric block having at least units derived from isobutylene, connected at each of its two ends to second thermoplastic blocks each comprising at least a first block consisting of units from at least a second polymerizable monomer and at least a second block consisting of units derived from 13-pinene, which can be used as an elastomeric layer; The inflation-resistant inflation-type astomer in a pneumatic object made it possible to obtain a pneumatic object having a good gas-tightness to the inflation gases, as well as a good compromise in terms of adhesion of the elements of the pneumatic object to each other and to terms of thermal resistance. The invention therefore relates to a pneumatic object provided with an elastomeric layer that is impervious to inflation gases, said elastomer layer predominantly comprising a blend of the following two thermoplastic elastomers: a) a first thermoplastic elastomer in the form of a first thermoplastic copolymer; blocks which comprises a first elastomer block comprising at least units derived from isobutylene, and having a glass transition temperature of less than or equal to -20 ° C., connected at one of its ends to a first thermoplastic block, said first block thermoplastic comprising at least a first block consisting of units derived from at least a first polymerizable monomer and at least a second block consisting of units derived from 13-pinene, b) a second thermoplastic elastomer in the form of a second block copolymer comprising a second elastomeric block having at least units derived from isobutylene, and resenting a glass transition temperature of less than or equal to -20 ° C, connected at each of its two ends to second thermoplastic blocks, said second thermoplastic blocks each comprising at least a first block consisting of units from at least one second polymerizable monomer and at least one second block consisting of units derived from 13-pinene. The composition of this blend, the particular structure and the composition of the block copolymers of this blend make it possible to impart to the airtight layer in the pneumatic object good adhesion properties both raw during the shaping and when cooked with the rubber components that are adjacent to it, in particular with the carcass ply. The composition of this blend, the particular structure and composition of the block copolymers of this blend also make it possible to confer on the pneumatic object a good thermal resistance, in particular in order to prevent the material from being pulled out when the pneumatic object is deburred. of the baking press but also makes it possible to avoid material creep during its use, in particular during thermomechanically demanding endurance tests. The invention also relates to a method for sealing a pneumatic object vis-à-vis the inflation gas, which is incorporated in said pneumatic object during its manufacture, or is added to said pneumatic object after its manufacture, an elastomeric layer gas-tight inflation as defined above. Finally, it is an object of the invention to use an inflation layer, in a pneumatic object, of an elastomeric layer as defined above. The invention as well as its advantages will be readily understood in the light of the description, the following exemplary embodiments and the single figure which schematizes, in radial section, a tire according to the invention. In the present description, unless expressly indicated otherwise, all the percentages (%) indicated are% by weight.

On the other hand, 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 that 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). In the present application, by "predominantly" designating a blend of elastomers, it is meant that this elastomer blend is predominant in all of the elastomers present in the elastomeric composition or the elastomeric layer, i.e. say that this elastomer blend represents more than 50% by weight of all the elastomers present in the elastomeric composition or the elastomeric layer. In the present application, the term "part per cent elastomer" or "phr" means the part by weight of one component per 100 parts by weight of the elastomer (s), that is to say, the total weight of the or elastomers, whether thermoplastic or non-thermoplastic. Thus, a 60 phr component will mean for example 60 g of this component per 100 g of elastomer or a blend of elastomers.

By block consisting of units derived from at least a first (or second) polymerizable monomer, it is meant that this block comprises at least one sequence of 5 units from at least a first (or a second) monomer, respectively. polymerizable.

By block consisting of units derived from P-pinene, it is meant that this block comprises at least one sequence of 3 units derived from β-pinene. By elastomeric block is meant that this block comprises at least one sequence of 5 units derived from isobutylene.

Thus, a first object of the invention is a pneumatic object provided with an elastomeric layer impervious to inflation gases, said elastomer layer predominantly comprising a blend of the following two thermoplastic elastomers: a) a first thermoplastic elastomer in the form of a first block copolymer which comprises a first elastomer block comprising at least units derived from isobutylene, and having a glass transition temperature of less than or equal to -20 ° C., connected at one of its ends to a first thermoplastic block, Said first thermoplastic block comprising at least a first block consisting of units derived from at least one first polymerizable monomer and at least one second block consisting of units derived from 13-pinene, b) a second thermoplastic elastomer in the form of a second block copolymer which comprises a second elastomeric block having at least units derived from the isobut utylene, and having a glass transition temperature less than or equal to -20 ° C, connected at each of its two ends to second thermoplastic blocks, said second thermoplastic blocks each comprising at least a first block consisting of units derived from at least one second polymerizable monomer and at least one second block consisting of units derived from 13-pinene. In the present invention, the vitreous transition temperature (denoted Tg) can be measured by the DMA (dynamic mechanical analysis) method of establishing the evolution curve of the elastic modulus G 'as a function of the temperature. According to this method, the glass transition temperature corresponds to the temperature at which the intersection between the line tangent to the vitreous plate and the line tangent to the transition zone between the vitreous plate and the rubber plateau is observed. Thus, in the present description, unless otherwise expressly indicated, the glass transition temperature is defined as the temperature at which the intersection between the line tangent to the vitreous plate and the line tangent to the transition zone between the plate is observed. glassy and rubbery plateau, during the temperature sweep of a reticulated sample (length of the sample length: 6 mm, width: 5 mm, thickness: 2 mm) subjected to a sinusoidal stress (frequency of 10 Hz). As indicated above, this Tg is measured during the measurement of dynamic properties, on a viscoanalyzer (DVA 200 - IT Instrumental Control), according to the JIS K 6384 standard (Testing Methods for Dynamic Properties of Vulcanized Rubber and Thermoplastic Rubber).

In a particularly preferred variant of the invention, the first thermoplastic block of the first block copolymer comprises a single first block consisting of units originating from at least one first polymerizable monomer and a single second block consisting of units originating from the 13 and the second thermoplastic blocks of the second block copolymer each comprise a single first block consisting of units derived from at least one first polymerizable monomer and a single second block consisting of units derived from 13-pinene. The first block copolymer preferably has a glass transition temperature (Tg, measured by DMA method) below -20 ° C, more preferably below -40 ° C, and even more preferably below -50 ° C. The second block copolymer preferably has a glass transition temperature (Tg, measured by DMA method) of less than -20 ° C, more preferably less than -40 ° C, and even more preferably less than -50 ° C. A value of Tg higher than these minima can reduce the performance of the waterproof layer during use at very low temperatures. The first block copolymer that can be used in the sealed elastomeric layer of the pneumatic object according to the invention preferably has a weight average molecular weight ranging from 15 to 150 kg / mol, more preferably from 60 to 125 kg / mol. The second block copolymer that can be used in the sealed elastomer layer of the pneumatic object according to the invention preferably has a weight average molecular weight ranging from 30 to 300 kg / mol, more preferably from 120 to 250 kg / mol. Below the indicated minima, the cohesion between the elastomer chains could be affected. In addition, in this case, an increase in the temperature of use could affect the mechanical properties, especially the properties at break, with consequent decreased "hot" performance. Moreover, too high molecular weights can be penalizing for the implementation of the gas-tight layer, which can be difficult or impossible. The weight average molecular weight (Mw) and number (Mn) of the first and second block copolymers that can be used according to the invention can be determined, in a manner known per se, by GPC (for "Gel Permeation Chromatography").

The GPC unit consists of four modules: "Waters 717 plus autosampler", "Waters 515 HPLC pump", "Water 2487" and "Water 2414". A sample of 0.05 ml solution is injected and passed through the columns (Shodexe GPC K-804 and Shodexe GPC K-802.5) using an eluent (chloroform) at a flow rate of 1.0 ml / min at 35 °. vs.

The first block copolymer that can be used in the sealed elastomer layer of the pneumatic object according to the invention generally has a polydispersity index (Ip = Mw / Mn) less than or equal to 3, more preferably less than or equal to 2, and even more preferably less than or equal to 1.5.

The second block copolymer that can be used in the sealed elastomer layer of the pneumatic object according to the invention also generally has a polydispersity index (Ip = Mw / Mn) less than or equal to 3, more preferably less than or equal to 2, and still more preferably less than or equal to 1.5.

As a reminder, the first block copolymer that can be used in the sealed elastomer layer of the pneumatic object according to the invention comprises a first elastomer block and a first thermoplastic block and the second block copolymer that can be used in the tight elastomeric layer of the object. pneumatic tire according to the invention 3033571 9 comprises a second elastomer block and two second thermoplastic blocks. The first (respectively second) elastomer of the first (respectively second) block copolymer comprises at least 5 units derived from isobutylene, and has a glass transition temperature of less than or equal to -20 ° C (Tg, measured by DMA method). Preferably, the first elastomer block has a glass transition temperature of less than or equal to -40 ° C, preferably less than or equal to -50 ° C. Preferably, the second elastomer block has a glass transition temperature of less than or equal to -40 ° C, preferably less than or equal to -50 ° C. In a first preferred variant of the invention, the first elastomer block further comprises from 0.5 to 6% by weight of units derived from one or more first conjugated dienes, preferably from 1.5 to 5% by weight. weight relative to the total weight of the first elastomer block. In a second preferred variant of the invention, the second elastomeric block further comprises from 0.5 to 6% by weight of units derived from one or more second conjugated dienes, preferably from 1.5 to 5% by weight. weight relative to the total weight of the second elastomer block. In a third preferred variant of the invention, the first elastomeric block further comprises from 0.5 to 6% by weight of units derived from one or more first conjugated dienes, preferably from 1.5 to 5% by weight. weight relative to the total weight of the first elastomer block and the second elastomer block further comprises from 0.5 to 6% by weight of units derived from one or more second conjugated dienes, preferably from 1.5 to 5% by weight relative to the total weight of the second elastomer block. The first (respectively second) conjugated dienes that can be copolymerized with isobutylene to form the first (respectively second) elastomeric block are conjugated C4-C14 dienes. Preferably, these conjugated dienes are chosen from isoprene, 1,3-butadiene, 1-methylbutadiene, 2-methylbutadiene, 2,3-dimethyl-1,3-butadiene and 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-pentadiene, dimethyl-1,3-pentadiene, 1,3-hexadiene, 2-methyl-1,3-hexadiene, 3-methyl-1,3-hexadiene, 4-methyl-1,3-hexadiene, 5-methyl 1,3-hexadiene, 2,3-dimethyl-1,3-hexadiene, 2,4-dimethyl-1,3-hexadiene, 2,5-dimethyl-1,3-hexadiene, 2- neopentylbutadiene, 1,3-cyclopentadiene, 1,3-cyclohexadiene, 1-vinyl-1,3-cyclohexadiene and mixtures thereof. More preferably, the first (respectively second) conjugated diene is isoprene or a mixture containing isoprene. Advantageously, the first elastomer block and / or the second elastomer block are halogenated. This halogenation makes it possible to increase the firing rate of the elastomer layer comprising the block copolymers. This halogenation makes it possible to improve the compatibility of the block copolymers with the other elements constituting the elastomer layer which is impervious to inflation gases. The halogenation is carried out in particular by means of bromine or chlorine, preferably bromine, on the units derived from conjugated dienes of the polymeric chain of the elastomeric blocks. Only a part of these units reacts with halogen. This portion of units derived from reactive conjugated dienes must nevertheless be 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 elastomer concerned.

As explained above, the first block copolymer that can be used in the sealing layer of the pneumatic object according to the invention comprises a thermoplastic block, called the first thermoplastic block in the present application.

The first thermoplastic block of this first block copolymer comprises at least a first block consisting of units originating from at least a first polymerizable monomer and at least a second block consisting of units derived from P-pinene.

As explained above, the second block copolymer usable in the sealing layer of the pneumatic object according to the invention comprises two thermoplastic blocks, called second thermoplastic blocks in the present application. The second thermoplastic blocks of this second block copolymer each comprise at least a first block consisting of units derived from at least one second polymerizable monomer and at least a second block consisting of units derived from P-pinene. Preferably, the first polymerizable monomer or monomers and / or the second polymerizable monomer or monomers are chosen from styrene monomers. By styrene monomer is meant in the present description, any monomer based on styrene, unsubstituted as substituted. The following monomers may notably be mentioned: styrene, methylstyrenes and especially alpha-methylstyrene, omethylstyrene, m-methylstyrene, p-methylstyrene, alpha-2-dimethylstyrene, alpha-4- dimethylstyrene and diphenylethylene; butylstyrenes, for example para-tert-butylstyrene; chlorostyrenes, for example, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, 2,4-dichlorostyrene, 2,6-dichlorostyrene and 2,4,6-trichlorostyrene; bromostyrenes, for example, o-bromostyrene, m-bromostyrene, p-bromostyrene, 2,4-dibromostyrene, 2,6-dibromostyrene and 2,4,6-tribromostyrene; fluorostyrenes, for example, o-fluorostyrene, m-fluorostyrene, p-fluorostyrene, 2,4-difluorostyrene, 2,6-difluorostyrene and 2,4,6-trifluorostyrene; and para-hydroxy-styrene. Preferably, the first polymerizable monomer or monomers and / or the second polymerizable monomer or monomers according to the invention are chosen from styrene, diphenylethylene, p-methylstyrene, p-tert-butylstyrene, p-chlorostyrene and p-tert-butylstyrene. -fluorostyrène. The first polymerizable monomer or monomers and / or the second polymerizable monomer or monomers may also be chosen from indenic monomers. By indene monomer is to be understood in the present description any monomer based on indene, unsubstituted as substituted. Among the substituted indenes may be cited for example alkyl indenes and aryl indenes.

As first and / or second polymerizable monomers, mention may also be made of the following compounds and their mixtures: acenaphthylene; those skilled in the art can, for example, refer to the article by Z. Fodor and J. P. Kennedy, Polymer Bulletin 1992 29 (6) 697-705; isoprene, then leading to the formation of a number of 1,4-trans polyisoprene units and cyclized units according to an intramolecular process; those skilled in the art may for example refer to the documents G. Kaszas, JE Puskas, P. Kennedy Applied Polymer Science (1990) 39 (1) 119-144 and JE Puskas, G. Kaszas, JP Kennedy, Macromolecular Science, Chemistry A28 (1991) 65-80; esters of acrylic acid, crotonic acid, sorbic acid, methacrylic acid, acrylamide derivatives, methacrylamide derivatives, acrylonitrile derivatives, derivatives of methacrylonitrile and mixtures thereof; mention may be made more particularly of adamantyl acrylate, adamantyl crotonate, adamantyl sorbate, 4-biphenylyl acrylate, tert-butyl acrylate, cyanomethyl acrylate and acrylate. 2-cyanoethyl acrylate, 2-cyanobutyl acrylate, 2-cyanohexyl acrylate, 2-cyanoheptyl acrylate, 3,5-dimethyladamantyl acrylate, 3,5-dimethyladamantyl crotonate, Espanol acrylate, pentachlorobenzyl acrylate, pentaflurobenzyl acrylate, pentachlorophenyl acrylate, pentafluorophenyl acrylate, adamantyl methacrylate, 4-tert-butylcyclohexyl methacrylate, methacrylate 3033571 tert-butyl methacrylate, 4-tert-butylphenyl methacrylate, 4-cyanophenyl methacrylate, 4-cyanomethylphenyl methacrylate, cyclohexyl methacrylate, 3,5-dimethyladamantyl methacrylate, dimethylaminoethyl methacrylate, methacrylate 3,3-dimethylbutyl, methacrylic acid, methyl methacrylate, ethyl methacrylate, phenyl methacrylate, isobornyl methacrylate, tetradecyl methacrylate, trimethylsilyl methacrylate, 2,3-xylenyl methacrylate, 2,6-methacrylate, xylenyl, acrylamide, N-sec-butylacrylamide, N-tert-butylacrylamide, N, N-diisopropylacrylamide, N-1-methylbutylacrylamide, N-methyl-N-phenylacrylamide, morpholylacrylamide, piperidylacrylamide, N-tert-butylmethacrylamide, 4-butoxycarbonylphenylmethacrylamide, 4-carboxyphenylmethacrylamide, 4-methoxycarbonylphenylmethacrylamide, 4-ethoxycarbonylphenylmethacrylamide, butyl cyanoacrylate, methyl chloroacrylate, ethyl chloroacrylate, isopropyl chloroacrylate, isobutyl chloroacrylate, cyclohexyl chloroacrylate, methyl fluoromethacrylate, methyl phenylacrylate, acrylonitrile, methacrylonitrile, and mixtures thereof. In a particularly preferred manner, the first monomer and / or the second polymerizable monomer is styrene. In a particular embodiment of the invention, the first monomer and the second polymerizable monomer are identical and may be selected from the monomers as described above. In this particular embodiment of the invention, the first polymerizable monomer and the second polymerizable monomer are preferably chosen from styrene monomers. Most preferably, in this particular mode of the invention, the first polymerizable monomer and the second polymerizable monomer are styrene. Particularly preferably in the block copolymer cutting that can be used according to the invention, the first and the second polymerizable monomer are not 13-pinene.

As explained above, the first thermoplastic block and the second thermoplastic blocks each comprise at least one block consisting of units derived from P-pinene. Preferably, the level of units derived from P-pinene in the first block copolymer varies from 0.5 to 10 mol%, preferably from 1 to 5 mol% relative to the number of moles of units. of the first block copolymer. Preferably, the level of units derived from P-pinene in the second block copolymer varies from 0.5 to 10 mol%, preferably from 1 to 5 mol% relative to the number of moles of units. second block copolymer. For a 13-pinene content of less than 10% in either one of the first and second block copolymers, the heat resistance of the inflation gas-tight layer is further improved. Likewise, for a 13-pinene level greater than 0.5%, the presence of 13-pinene may be able to have an effect on perceptible adhesion. The first thermoplastic block generally represents from 5 to 30% by weight, preferably from 10 to 25% by weight relative to the total weight of the first block copolymer.

The second thermoplastic blocks generally represent from 5 to 30% by weight, preferably from 10 to 25% by weight relative to the total weight of the second block copolymer. Preferably, the first block copolymer represents from 5 to 35% by weight, preferably from 10 to 30% by weight relative to the weight of the second block copolymer. In a very particularly preferred variant of the invention, the first block copolymer comprises a first elastomer block consisting of units derived from isobutylene, and having a glass transition temperature of less than or equal to -20 ° C., connected to 30 one of its ends to a first thermoplastic block which comprises a first block consisting of units derived from styrene and a second block consisting of units from 13-pinene and the second block copolymer comprises a second elastomeric block consisting of units derived from isobutylene, and having a glass transition temperature of less than or equal to -20 ° C, connected at each of its two ends to second thermoplastic blocks which each comprise a first block consisting of styrene units and a second block consisting of units from 13-pinene.

In a first embodiment of this variant, the first block copolymer consists of the following blocks: polyisobutylene / polystyrene / poly-13-pinene and the second block copolymer consists of the following blocks: poly Pinene / polystyrene / polyisobutylene / polystyrene / poly-13-pinene.

In a second embodiment of this variant, the first block copolymer consists of the following blocks: polyisobutylene / poly-13-pinene / polystyrene and the second block copolymer consists of the sequence of the following blocks: polystyrene poly-13-pinene / polyisobutylene / poly-13-pinene / polystyrene. The cutting of block copolymers that can be used according to the invention gives the inflation-gas-tight composition which contains it a high adhesion capacity to the rubber components of the pneumatic object, in particular pneumatic tires, which are associated with it. . In addition, this cutting of block copolymers, despite its thermoplastic nature, gives the gas-tight composition which contains it a good hot cohesion of the material, especially at temperatures ranging from 150 to 200 ° C. These temperatures correspond to the cooking temperatures of tires. This high-temperature cohesion allows hot demolding of these tires without altering the integrity of the gas-tight composition containing the block copolymer cutting used according to the invention. Also, the block copolymer cutting that can be used according to the invention makes it possible, surprisingly, to satisfy a compromise of properties, often antinomic, of hot cohesion of the composition which contains it and of adhesion thereof. on the rubber components that are adjacent to it in the pneumatic object. This property compromise is achieved while maintaining the sealing properties and workability of the composition comprising this block copolymer cutting, as well as imparting improved hysteresis properties (compared to butyl rubber) as an inner rubber for pneumatic tires. Blending of block copolymers that can be used in the sealed elastomer layer of the pneumatic object according to the invention can be prepared by synthetic methods known per se and described in the literature, in particular that cited in the presentation of the state of the invention. 10 technique of the present description. 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 characteristics of the block copolymer cutting structure that can be used according to the invention.

The blending of block copolymers can be prepared either by separate synthesis of the two block copolymers from the blending followed by blending of the two block copolymers, or by parallel synthesis in the same container of the two block copolymers. Several synthetic strategies can be implemented to prepare block copolymers usable according to the invention. These strategies apply in the two cases mentioned above of the preparation of the block copolymer cutting. Indeed, those skilled in the art will be able to adapt these strategies to the first case, that is to say to the separate synthesis of the two block copolymers and then to their mixture but also to the second case, that is to say when the Block copolymers are synthesized in parallel in the same container. A first strategy consists of a first step of synthesis of the elastomeric block (s) by living cationic polymerization of the monomers to be polymerized by means of a monofunctional initiator, to prepare the first block copolymer, and / or of a difunctional initiator, for prepare the second block copolymer. These initiators are well known to those skilled in the art.

In the case where both block copolymers are synthesized in the same container, it should be understood that it is necessary to have both a monofunctional initiator and a di-functional initiator.

This step is then followed by a second step of synthesizing the thermoplastic block (s) by polymerization of at least a first and / or second polymerizable monomer or a 13-pinene monomer on the living elastomeric blocks obtained in the first step, then a third step of synthesis of the thermoplastic block (s) by polymerization respectively of a 13-pinene monomer or of at least a first and / or second polymerizable monomer, on the living blocks resulting from of the second stage. Thus, these three steps are consecutive, which results in the addition of: monomers to be polymerized for the preparation of the elastomeric block (s): isobutylene alone or mixed with one or more conjugated diene monomers; one or more first and / or second polymerizable monomers or 13-pinene, 13-pinene or one or more first and second polymerizable monomers. At each step, the monomer (s) to be polymerized may or may not be added in the form of a solution in a solvent as described hereinafter, in the presence or absence of an acid or a Lewis base such as described below. Each of these steps can be carried out in the same reactor or in two or three different polymerization reactors. Preferably, these two steps are carried out in a single reactor ("one-pot" synthesis). The living cationic polymerization is conventionally carried out by means of an initiator and optionally of a Lewis acid acting as a co-initiator in order to form a carbocation in situ.

Usually, electro-donating compounds are added in order to impart a living character to the polymerization. By way of illustration, the monofunctional initiators that can be used for the preparation of the first block copolymer that can be used according to the invention can be chosen from (2-methoxy-2-propyl) -benzene (cumylmethyl ether), (2- chloro-2-propyl) -benzene (cumyl chloride), (2-hydroxy-2-propyl) -benzene and (2-acetoxy-2-propyl) -benzene. By way of illustration, the difunctional initiators that can be used for the preparation of the second block copolymer that may be used according to the invention may be chosen from 1,4-di (2-methoxy-2-propyl) -benzene (or dicumylmethyl ether). ), 1,4-di (2-chloro-2-propyl) benzene (or dicumyl chloride), 1,4-di (2-hydroxy-2-propyl) benzene, 1,4-di (2-acetoxy-2-propyl) -benzene, 2,6-dichloro-2,4,4,6-tetramethylheptane and 2,6-dihydroxy-2,4,4,6-heptane. As a preferred monofunctional initiator, cumyl chloride is used. Preferentially as difunctional initiators are used dicumyl ethers or dicumyl halides and preferably dicumyl chloride. The Lewis acids may be chosen from metal halides of the general formula MXn where M is a member chosen from Ti, Zr, Al, Sn, P and B, X is a halogen such as Cl, Br, F or I and n corresponding to the degree of oxidation of the element M. For example, TiCl 4, AlCl 3, BCl 3, BF 3, SnCl 4, PCl 3, PCl 5. The compounds TiC14, AlCl3 and BCl3 are used as preferred, and TiCl4 even more preferentially. The electro-donating compounds may be selected from known Lewis bases, such as pyridines, amines, amides, esters, sulfoxides, and the like. 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.

The apolar solvents which can be used for the synthesis of the block copolymers which can be used according to the invention are, for example, hydrocarbon, aliphatic, cycloaliphatic or aromatic solvents, such as hexane, heptane, cyclohexane, methylcyclohexane, benzene or toluene. The polar solvents that can be used for the synthesis of the block copolymers that can be used according to the invention are, for example, halogenated solvents such as alkane halides, such as methyl chloride (or chloroform), ethyl chloride, chloride Butyl, methylene chloride (or dichloromethane) or chlorobenzenes (mono-, di- or tri-chloro). Those skilled in the art will be able to choose the appropriate temperature conditions in order to achieve the molecular weight characteristics of these copolymers.

A second strategy of synthesis consists in separately preparing: a telechelic elastomer block, for preparing the second block copolymer and / or a functional elastomeric block at one of its chain ends, for preparing the first block copolymer, by living cationic polymerization by means of a monofunctional and / or difunctional initiator, optionally followed by functionalization reaction on the chain ends, and then reacting them with either the thermoplastic block or blocks (first and / or second polymerizable monomer) 13-pinene) previously prepared by anionic polymerization, or on one of the at least two blocks of the previously prepared thermoplastic blocks (respectively 13-pinene or first and / or second polymerizable monomer) and then reacting the polymer thus formed on the at least two other blocks of the thermoplastic block or blocks (first and / or second respectively) polymerizable monomer or 13-pinene) and so on in the case where there are several 13-pinene blocks and / or more blocks derived from a first and / or a second polymerizable monomer. The nature of the reactive functions at each of the chain ends of the elastomeric blocks and optionally of the thermoplastic block (s) and the proportion of living thermoplastic blocks with respect to the elastomeric blocks will be chosen by those skilled in the art to obtain a cutting of block copolymers that can be used according to the invention.

The possible halogenation of the block copolymers which can be used according to the invention obtained according to one or other of the synthesis strategies is carried out according to any method known to those skilled in the art, in particular those used for the halogenation of the butyl rubber and can be made for example by means of bromine or chlorine, preferably bromine, on the units derived from conjugated dienes of the polymer chain of the elastomeric blocks, when they are present, or on the units derived from the pinene. Preferably, the preparation of the block copolymer cut that can be used according to the invention will be carried out by living cationic polymerization by means of a monofunctional initiator and a difunctional initiator and by addition of the monomers to be polymerized for the synthesis of the elastomeric blocks. then by consecutive addition of the monomers to be polymerized for the synthesis of the thermoplastic block or blocks.

The present invention is not restricted to a specific polymerization process from such a monomer mixture. This type of process is known to those skilled in the art. Thus, syntheses described in the prior art, in particular in patent documents EP 731 112, US Pat. No. 4,946,899 and US Pat. No. 5,260,383, can be implemented by analogy to prepare the block copolymer cutting that can be used according to the invention. . The block copolymer cutting that can be used according to the invention can in itself form the elastomeric composition constituting the gas-tight elastomeric layer or be associated in this elastomer layer with other constituents. If any other elastomers are used in this elastomeric composition, the block copolymer cut that can be used according to the invention constitutes the majority elastomers by weight; they then represent more than 50%, more preferably more than 70% by weight of all the elastomers. Such minor complementary elastomers could be, for example, diene elastomers such as natural rubber or synthetic polyisoprene, butyl rubber or thermoplastic styrene elastomers (TPS) other than the block copolymers which can be used according to the invention, within the limit the compatibility of their microstructures. As a TPS elastomer other than the block copolymers that may be used according to the invention, mention may be made in particular of a TPS elastomer selected from the group consisting of styrene / butadiene / styrene block copolymers, styrene / isoprene / styrene block copolymers, styrene / isoprene / butadiene / styrene block copolymers, styrene / ethylene / butylene / styrene block copolymers, styrene / ethylene / propylene / styrene block copolymers, styrene / ethylene / ethylene / propylene / styrene block copolymers and blends of styrene / ethylene / butylene / styrene block copolymers these copolymers. More preferably, said optional additional TPS elastomer is selected from the group consisting of styrene / ethylene / butylene / styrene block copolymers, styrene / ethylene / propylene / styrene block copolymers and mixtures of these copolymers. However, according to a preferred embodiment, the block copolymers used according to the invention are the only elastomers present in the gas-tight elastomeric layer. The previously described block copolymer cutting is sufficient on its own for the gas-tight function to be performed with respect to the pneumatic objects in which it is used. However, according to a preferred embodiment of the invention, the latter is used in a composition which also comprises, as plasticizer, an extender oil (or plasticizing oil) whose function is to facilitate the setting in particular, the integration into the pneumatic object by a lowering of the module and an increase in tackiness of the gas-tight layer.

Thus, in this preferred embodiment of the invention, the inflation gas-tight elastomeric layer further comprises an extension oil. As an extension oil, any extension oil, preferably of a slightly polar nature, capable of extending and plasticizing elastomers, in particular 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 Especially resins or rubbers which are inherently solid. Preferably, the extender oil is selected from the group consisting of polyolefinic oils (i.e., derived from the polymerization of olefins, monoolefins or diolefins), paraffinic oils, naphthenic oils (with low or high viscosity), aromatic oils, mineral oils, and blends of these oils. More preferably, the extender oil is selected from olefinic oils, and preferably is a polyisobutylene oil. (abbreviated as "GDP"). Indeed, this oil has demonstrated the best compromise properties compared to other oils tested, including a conventional oil paraffinic type. By way of examples, polyisobutylene oils are sold in particular by the company UNIVAR under the name "Dynapak Poly" (for example "Dynapak Poly 190"), by INEOS Oligomer under the name INDOPOL H1200, by BASF under the names "Glissopal". "(Eg" Glissopal 1000 ") or" Oppanol "(eg" Oppanol B12 "); paraffinic oils are sold for example by EXXON under the name "Telura 618" or by Repsol under the name "Extensol 51". The extender oil preferably has a number-average molar mass ranging from 350 to 4000 g / mol, more preferably ranging from 400 to 3000 g / mol.

The number average molecular weight (Mn) of the extender oil, when present, can be determined by size exclusion chromatography (SEC); the oil sample is first solubilized in tetrahydrofuran at a concentration of about 1 g / l; then the solution is filtered on a porosity filter 0.45 i.tm before injection. The equipment used is a 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. A set of two WATERS columns of trade names "STYRAGEL HT6E" is used. The injected volume of the solution of the oil sample is 100 1.11. 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. Indeed, it has been shown that for too low average molecular weights, there is a risk of migration of the oil out of the composition, while too high masses can lead to excessive stiffening of this composition. composition. This choice has proven to be an excellent compromise for the intended applications, particularly for use in a tire. Preferably, the extender oil is present at a content greater than 5 phr, preferably between 5 and 100 phr (parts by weight per hundred parts of total elastomers, that is to say the copolymers blocks usable according to the invention as well as any other elastomer present in the composition or elastomeric layer).

Below the minimum indicated, the elastomer composition may have too high rigidity for certain applications while beyond the maximum recommended, there is a risk of insufficient cohesion of the composition and loss of sealability be harmful depending on the application.

For these reasons, particularly for use of the airtight composition in a tire, it is preferred that the extender oil content be greater than 10 phr, in particular between 10 and 90 phr, more preferably still than it is greater than 5 20 phr, in particular between 20 and 80 phr. The inflation-gas-tight elastomeric layer described above may also include the various additives usually present in the elastomeric air-tightness layers known to those skilled in the art.

Examples of reinforcing fillers are, for example. Any type of reinforcing filler known for its ability to reinforce a rubber composition usable for the manufacture of tires, for example carbon black, a reinforcing inorganic filler such as silica, or a blend of these two, can be used. types of filler, including carbon black and silica. Suitable carbon blacks are all carbon blacks, used individually or in the form of mixtures, in particular blacks of the HAF, ISAF, SAF type conventionally used in tires (so-called pneumatic grade blacks). It is also possible to use, according to the targeted applications, blacks of higher series FF, FEF, GPF, SRF. The carbon blacks could for example already be incorporated into the diene elastomer in the form of a masterbatch, before or after grafting and preferably after grafting (see for example WO 97/36724 or WO 99/16600). As a reinforcing inorganic filler other than carbon black, in the present application is meant by definition any inorganic or inorganic filler as opposed to carbon black, capable of reinforcing on its own, with no other means than intermediate coupling, a rubber composition for the manufacture of tires; such a filler is generally characterized, in known manner, by the presence of hydroxyl groups (-OH) on its surface.

The physical state in which the reinforcing filler is present is indifferent, whether in the form of powder, microbeads, granules, beads or any other suitable densified form. Of course, reinforcing filler is also understood to mean mixtures of different reinforcing fillers, in particular highly dispersible siliceous and / or aluminous fillers as described below. Suitable reinforcing inorganic fillers other than carbon black are, in particular, mineral fillers of the siliceous type, in particular of silica (SiO 2), or of the aluminous type, in particular alumina (Al 2 O 3). Preferably, the level of reinforcing filler in the sealed elastomer layer varies from 10 to 200 phr, more preferably from 30 to 150 phr, in particular from 50 to 120 phr, the optimum being, in a manner known per se, different according to particular applications targeted. According to one embodiment, the reinforcing filler mainly comprises silica, preferably the level of carbon black present in the sealed elastomeric layer being less than 20 phr, more preferably less than 10 phr (for example between 0.5 and 20 phr). , In particular from 1 to 10 phr). Preferably, the reinforcing filler predominantly comprises carbon black, or is exclusively composed of carbon black. When the reinforcing filler comprises a filler requiring the use of a coupling agent to establish the bond between the filler and the elastomer, the sealed elastomer layer further comprises, in a conventional manner, an agent capable of effectively providing this link. When the silica is present in the impermeable elastomeric layer as a reinforcing filler, an at least bifunctional coupling agent (or bonding agent) is used in known manner to provide a sufficient chemical and / or physical connection. between the inorganic filler (surface of its particles) and the thermoplastic elastomer, in particular organosilanes or bifunctional polyorganosiloxanes.

In the impervious elastomeric layer that can be used according to the invention, the content of coupling agent preferably varies from 0.5 to 12 phr, it being understood that it is generally desirable to use as little as possible. The presence of the coupling agent is dependent on that of the reinforcing inorganic filler other than carbon black. Its rate is easily adjusted by the skilled person according to the rate of this charge; it is typically of the order of 0.5 to 15% by weight relative to the amount of reinforcing inorganic filler other than carbon black.

Those skilled in the art will understand that as an equivalent load of the reinforcing inorganic filler other than carbon black, a reinforcing filler of another nature could be used, provided that this reinforcing filler is covered with an inorganic layer. such as silica, or would have on its surface functional sites, in particular hydroxyl sites, requiring the use of a coupling agent to establish the bond between the filler and the thermoplastic elastomer. The waterproof elastomeric layer that can be used according to the invention may also contain reinforcing organic fillers that can replace all or part of the carbon blacks or other reinforcing inorganic fillers described above. Examples of reinforcing organic fillers that may be mentioned are functionalized polyvinyl organic fillers as described in applications WO-A-2006/069792, WO-A-2006/069793, WO-A-2008/003434 and WO-A -2008/003435. As other additives usually present in the elastomeric layers impervious to inflation gases known to those skilled in the art, mention will be made, for example, of non-reinforcing or inert fillers, coloring agents which can advantageously be used for coloring the composition, lamellar fillers further improving the seal (for example phyllosilicates such as kaolin, talc, mica, graphite, clays or clays modified ("organo clays"), plasticizers other than the above-mentioned extension oils, protective agents such as antioxidants or antiozonants, anti-UV agents, various setting agents or other stabilizers, or alternatively promoters capable of promoting adhesion to the rest of the structure of the pneumatic object. 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. According to a preferred embodiment of the invention, this gas-tight elastomer layer has a secant modulus in extension, at 10% elongation (denoted M10), 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 gas-tight elastomeric layer previously described can be used as a gas-tight layer in any type of pneumatic object. Examples of such pneumatic objects include pneumatic boats, balls or balls used for play or sport.

It is particularly well suited for use as an airtight layer (or any other inflation gas, eg nitrogen) in a pneumatic object, finished or semi-finished product, of rubber, especially in a pneumatic tire for motor vehicle such as a two-wheeled vehicle, tourism or industrial. 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 gas-tight layer preferably has a thickness greater than or equal to 0.05 mm, preferably from 0.1 to 10 mm, and more preferably from 0.1 to 2 mm. It will be readily understood that, depending on the specific fields of application, the dimensions and the pressures involved, the mode of implementation of the invention may vary, the gas-tight elastomeric layer then having several preferential thickness ranges. . For example, for passenger-type tires, it may have a thickness of at least 0.4 mm, preferably between 0.8 and 2 mm. In another example, for pneumatic tires of heavy goods vehicles or agricultural vehicles, the preferred thickness may be between 1 and 3 mm. In another example, for tire tires of vehicles in the field of civil engineering or for aircraft, the preferred thickness may be between 2 and 10 mm. The pneumatic object according to the invention is preferably a tire. In general, the pneumatic object according to the invention is intended to equip motor vehicles of tourism type, SUV 15 ("Sport Utility Vehicles"), two wheels (including motorcycles), aircraft, as well as industrial vehicles such as vans, trucks and other transport or handling vehicles. As heavy goods vehicles, it will be possible to include metros, buses and road transport vehicles such as trucks, tractors, trailers and off-the-road vehicles such as agricultural or civil engineering machinery. The invention also relates to a method for sealing a pneumatic object with respect to the inflation gases, in which said pneumatic object is incorporated during its manufacture, or said pneumatic object is added after its manufacture, an elastomeric layer which is impervious to inflation gas as defined above. Preferably in this sealing process, the elastomeric layer impervious to inflation gases is deposited on the inner wall of the pneumatic object.

In a particular variant of this process, the pneumatic object is a pneumatic tire. In this particular variant, during a first step, the inflation-gas-tight elastomeric layer is deposited flat on a manufacturing drum, before covering said inflation-gas-tight elastomer layer with the rest of the structure of the tire. pneumatic tire. Finally, the invention relates to the use as a gas-tight layer in a pneumatic object of an elastomeric layer as defined above. The invention as well as its advantages will be understood more fully, in the light of the single figure which schematizes, in radial section, a tire according to the invention, as well as examples of embodiments which follow.

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 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 not shown 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 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 25 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). The inner wall of the tire 1 has an airtight layer 10, eg of thickness about 0.9 mm, on the side of the inner cavity 11 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 up to the level of the rim hook when the tire 3033571 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 the swelling and pressurization of the tire; its sealing properties must enable it to guarantee a relatively low rate of pressure loss and to maintain the swollen bandage, in normal operating condition, for a sufficient duration, normally of several weeks or several months.

In contrast to a conventional tire using a butyl rubber composition, the tire according to the invention uses in this example, as an inflation-gas-tight layer, a thermoplastic elastomer in the form of a mixture of blocks as described above. The tire provided with its airtight layer 10 as described above can be produced before or after vulcanization (or firing).

Methods of Measurement 1) Leak Test For this analysis, a rigid wall permeameter was used, placed in an oven (temperature of 60 ° C in the present case), provided with a relative 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 1.5 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 3033571 31 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. An arbitrary value of 100 is given for the airtightness of the control, a result greater than 100 indicating an increase in airtightness and therefore a decrease in permeability. 2) Adhesion Test (or Peeling): Inflatable Gas Elastomer Layer / Diene Elastomer Layer Adhesion tests (peel tests) were conducted to test the elastomeric layer suitability after being cured to a layer of diene elastomer, more specifically to a conventional rubber composition for tire carcass reinforcement, based on natural rubber (peptized) and carbon black N330 (65 parts by weight); 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 between two calendered fabrics first with a SIBS elastomer (1.5 mm) and the other with the mixture. diene considered (1.2 mm). A rupture primer is inserted between the two calendered fabrics at the end of the thin layer. The test piece after assembly was vulcanized at 180 ° C under pressure for 10 minutes. Strips 30 mm wide were cut with a cutter. Both sides of the breakout primer were then placed in the jaws of an Introne brand pulling 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 strength curve is obtained per unit 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.

An arbitrary value of 100 is given for the adhesion of the control, a result greater than 100 indicating an increase in adhesion. 3) Thermal resistance test (or test for determining a softening temperature) To characterize the softening temperature of an elastomeric composition, the following test is used: Apparatus: dynamic mechanical analyzer (DMA Q800) marketed by the company TA Instruments; - Sample: cylindrical, it is made by means of a punch and measures an average of 13 mm in diameter for a thickness of 2 mm; Solicitation: the sample holder is in the form of a compression jaw; this piece consists of a movable top plate (15 mm in diameter) and a fixed lower plate (15 mm in diameter); the sample is placed between these two trays; the moving part makes it possible to apply a constraint defined on the sample, of 1N; the assembly is placed in an oven making it possible to carry out a temperature ramp from ambient to 180 ° C. at 3 ° C./min, during which the deformation of the sample is recorded; - Interpretation: the results are in the form of a deformation curve of the sample as a function of temperature; the softening temperature is considered to be that for which the material has a decrease in its thickness of 10 °. An arbitrary value of 100 is given for the heat resistance of the control, a result greater than 100 indicating an increase in thermal resistance.

EXAMPLE 1 Preparation of a reference block copolymer (polymer 1) - styrene / isobutylene / styrene block copolymer The block copolymer (polymer 1) is synthesized as follows: A separable flask (polymerization vessel) of 500 ml is put under nitrogen, then n-hexane (molecular sieve dried, 23.8 ml) and butyl chloride (molecular sieve dried, 214.4 ml) are added by syringe. The polymerization vessel is then cooled by immersion in a dry ice / methanol bath at -70 ° C. A Teflon feed tube is connected to a pressure-resistant glass collection flask equipped with a three-way tap and containing isobutylene (75 ml, 794 mmol), isobutylene is added to the polymerization vessel by means of a nitrogen pressure. Then, p-dicumyl chloride (0.1248 g, 0.540 mmol) and α-picoline (0.1026 g, 1.10 mmol) are added. Titanium tetrachloride (0.84 ml, 7.70 mmol) is then added to start the polymerization. After stirring for one hour at the same temperature (-70 ° C.), a sample of the polymerization solution (about 1 ml) is extracted from the total polymerization solution. Styrene (9.79 g, 94.1 mmol), previously cooled to -70 ° C, is then added to the polymerization vessel. 45 minutes after the addition of styrene, the polymerization solution is poured into hot water (500 ml) in order to stop the reaction and this mixture is then stirred for 30 minutes. Then, the polymerization solution is washed with deionized water (3x 500 ml). The solvent and the analogs are evaporated from the washed reaction crude under reduced pressure at 80 ° C for 24 hours to obtain the block copolymer. The weight average molecular weights of the central block (polyisobutylene) and of the entire block copolymer are measured by permeate gel chromatography (GPC) as defined above and the glass transition temperature is measured by the DMA method as defined above. . These data are collated in Table I, hereinafter. EXAMPLE 2 Preparation of a Comparative Block Copolymer 5 (Polymer 2) Pinene / Styrene / Isobutylene / Styrene / 13-Pinene Block Copolymer The block copolymer copolymer (Polymer 2) is synthesized as follows: A separable balloon ( polymerization) of 2 liters is put under nitrogen, then n-hexane (molecular sieve dried, 192 ml) and butyl chloride (molecular sieve dried, 768 ml) are added by means of a syringe. The polymerization vessel is then cooled by immersion in a dry ice / methanol bath at -70 ° C. A Teflon feed tube is connected to a pressure-resistant glass collection flask equipped with a three-way stopcock and containing isobutylene (175 ml, 1852 mmol), isobutylene is added to the reaction vessel. polymerization by means of a nitrogen pressure. Then, p-dicumyl chloride (0.1413 g, 0.611 mmol) and α-picoline (1.7091 g, 18.3 mmol) are added. Then, titanium tetrachloride (5.36 mL, 48.9 mmol) is added to start the polymerization. After stirring for 90 minutes at the same temperature (-70 ° C), a sample of the polymerization solution (about 1 ml) is extracted from the total polymerization solution.

Styrene (28.9 mL, 251 mmol) is then added and the medium is stirred until the styrene conversion has reached 70 ° A. The conversion of styrene is followed by gas chromatography. Then, 13-pinene (7.47 ml, 47.7 mmol), previously cooled to -70 ° C, is added to the polymerization vessel. After 30 minutes, titanium tetrachloride (0.30 mL, 2.74 mmol) is added again and the medium is stirred for 20 minutes. The polymerization solution is then poured into hot water (2 liters) in order to stop the reaction and this mixture is then stirred for 30 minutes. Then, the polymerization solution is washed with deionized water (3x 2 L). The solvent and the analogs are evaporated from the washed reaction crude under reduced pressure at 80 ° C for 24 hours to obtain the block copolymer. The weight average molecular weights of the central block (polyisobutylene) and of the entire block copolymer are measured by permeate gel chromatography (GPC) as defined above and the glass transition temperature is measured according to the DMA method as defined above. These data are collated in Table I, hereinafter. EXAMPLE 3 Preparation of a Polymer Based on a Block Copolymer Cutting Usable in the Pneumatic Object According to the Invention (Polymer 3) 1-Pinene / Styrene / Isobutylene / Styrene / 13-Pinene Block Copolymer ( triblock copolymer) and isobutylene / styrene / 13-pinene block copolymer (diblock copolymer) (10% by weight of diblock copolymer relative to the triblock copolymer) Polymer 3 is synthesized as follows: A separable flask (polymerization vessel) of 5 liters is put under nitrogen, then n-hexane (dried on molecular sieve, 576 ml) and butyl chloride (dried on molecular sieve, 2306 ml) are added by syringe. The polymerization vessel is then cooled by immersion in a dry ice / methanol bath at -70 ° C. A Teflon feed tube is connected to a pressure-resistant glass collection flask equipped with a three-way tap and containing isobutylene (547 mL, 5791 mmol), isobutylene is added to the polymerization vessel by means of a nitrogen pressure. Then, p-dicumyl chloride (0.3978 g, 1.72 mmol), cumyl chloride (0.0591 g, 0.382 mmol) and α-picoline (5.134 g, 55.1 mmol) are added together. Then, the titanium tetrachloride (16.0 ml, 146 mmol) is added to start the polymerization. After stirring for 70 minutes at the same temperature (-70 ° C), a sample of the polymerization solution (about 1 ml) is extracted from the total polymerization solution. Styrene (90.2 ml, 783 mmol) is then added and the medium is stirred until the styrene conversion has reached 70%. The conversion of styrene is followed by gas chromatography. Then 13-pinene (23.4 ml, 149 mmol), previously cooled to -70 ° C, is added to the polymerization vessel.

After 60 minutes, the polymerization solution is then poured into hot water (5 liters) in order to stop the reaction and this mixture is then stirred for 30 minutes. Then, the polymerization solution is washed with deionized water (3x 5 L). The solvent and the analogs are evaporated from the washed reaction crude under reduced pressure at 80 ° C for 24 hours to obtain the block copolymers. The weight average molecular weights of the central blocks (polyisobutylene) and of the second entire block copolymer (that comprising two thermoplastic blocks) are measured by permeate gel chromatography (GPC) as defined above and the glass transition temperature of the elastomeric blocks. diblock copolymer and triblock copolymer is measured according to the DMA method as defined above. These data are collated in Table I, hereinafter.

EXAMPLE 4 Preparation of a polymer based on a block copolymer cut-out suitable for use in the pneumatic object according to the invention (polymer 4) 13-pinene / styrene / isobutylene / styrene / 13-pinene block copolymer ( triblock copolymer) and isobutylene / styrene / 13-pinene block copolymer (diblock copolymer) (20% by weight of diblock copolymer relative to the triblock copolymer) The polymer 4 is prepared in the same manner as the polymer 3, with different for the following species: n-hexane 3033571 (4989 mmol); butyl chloride (24981 mmol); isobutylene (6510 mmol); p-dicumyl chloride (1.72 mmol); cumyl chloride (0.86 mmol); a-picoline (61.9 mmol); titanium tetrachloride (165 mmol); styrene (879 mmol); 13-pinene (134 mmol).

The weight average molecular weights of the central blocks (polyisobutylene) and the second whole block copolymer (the one comprising two thermoplastic blocks) as well as the glass transition temperature of the elastomeric blocks of the diblock copolymer and the triblock copolymer are measured in the same way. as in Example 3. These data are collated in Table I, hereinafter. EXAMPLE 5 Preparation of a polymer based on a block copolymer cut-out suitable for use in the pneumatic object according to the invention (polymer 5) 1-pinene / styrene / isobutylene / styrene / 13-pinene block copolymer ( triblock copolymer) and isobutylene / styrene / 13-pinene block copolymer (diblock copolymer) (40% by weight of diblock copolymer relative to the triblock copolymer) The polymer 5 is prepared in the same manner as the polymer 3, with different for the following species: n-hexane (6656 mmol); butyl chloride (33325 mmol); isobutylene (8686 mmol); p-dicumyl chloride (1.72 mmol); cumyl chloride (2.29 mmol); a-picoline (82.6 mmol); titanium tetrachloride (220 mmol); styrene (1170 mmol); 13-pinene (134 mmol). The weight average molecular weights of the central blocks (polyisobutylene) and the second entire block copolymer (the one comprising two thermoplastic blocks) as well as the glass transition temperature of the elastomer blocks of the diblock copolymer and the triblock copolymer are measured in the same way. as in Example 3. These data are collated in Table I, hereinafter.

Table I This table collects the values of weight average molar masses (Mw) of the block copolymer alone (for references 1 and 2) or the second block copolymer (for references 3, 4 and 5), the rate of units derived from the 13-pinene of the block copolymer alone (for references 1 and 2) or in the mixture (for references 3, 4 and 5) in moles relative to the number of moles of units of the block copolymer only (for references 1 and 2) or mixture (for references 3, 4 and 5) (% P-pinene), the weight percentage of the thermoplastic block (s) in the block copolymer alone (for references 1 and 2) or in the mixture (for references 3, 4 and 5) (% TP blocks), the weight percentage of the first block copolymer (diblock copolymer) based on the weight of the second block copolymer (triblock copolymer) (% diblocs) and the glass transition temperature of the elastomeric blocks of the copolymer single block (for references 1 and 2) or the elastomeric blocks of the mixture (for references 3, 4 and 5). In the case of mixing, the value of the glass transition temperature is the same whether the copolymers are diblock or triblock. 1 2 3 4 5 (Ref.) (Comp.) (Inv.) (Inv.) (Inv.) Mw (in 100 200 190 180 160 kg / mol)% P-pinene 0 2.3 2.3 2, 3 2.3% TP blocks 15 15 15 15 15 diblocks 0 0 10 20 40 Tg -60 ° C -59 ° C -62 ° C -59 ° C -59 ° C elastomer 3033571 39 Example 6: Preparation and evaluation of elastomeric layer impervious to inflation gases (matrix 100% cut of block copolymers) Block copolymers (polymers 1 and 2) and blends of block copolymers (polymers 3 and 4, having respectively 10 and 20% by weight of diblock copolymers with respect to the triblock copolymer) obtained above were formulated in inflation gas-tight layers consisting of 100% block copolymer (respectively layers 1 and 2) or 100% of the block copolymer blend ( respectively layers 3 and 4). The sealed elastomeric thermoplastic layers of the invention are prepared conventionally, for example, by incorporating the one or more block copolymers into a twin screw extruder, so as to effect the melting of the matrix, and then use a flat die for producing the thermoplastic layer. More generally, the shaping of the thermoplastic may be made by any method known to those skilled in the art: extrusion, calendering, extrusion blow molding, injection, cast film ("cast film" in English).

The properties of these watertight layers were then evaluated. The data are collated in Table II below.

Table II This table collects the normalized values (relative to layer 1) of the sealing, adhesion and heat resistance of the elastomeric layers prepared using the polymers previously synthesized above.

3033571 Sealing Adherence Thermal resistance Layer 1 100 100 100 Layer 2 70 240 142 Layer 3 84 800 124 Layer 4 82 720 112 Comparing the sealing performance of the layers according to the invention 3 and 4 and the comparative layer 2 evidence that the presence of block copolymer cutting further improves the sealing performance and that while the layer 2 already has satisfactory results. The presence of block copolymer cutting also makes it possible to obtain a much better adhesion performance, whereas the layer 2 already has good results and this without degradation of the thermal resistance. Example 7: Preparation of Comparative Block Copolymer (Polymer 6) Pinene / Styrene / Isobutylene / Styrene / 13-Pinene Block Polymer Polymer Polymer 6 is prepared in the same manner as Polymer 2, with different amounts to the following species: n-hexane (902 mmol); butyl chloride (4516 mmol); isobutylene (1303 mmol); p-dicumyl chloride (0.61 mmol); a-picoline (18.3 mmol); titanium tetrachloride (37 mmol then 1.8 mmol); styrene (250 mmol); 13-pinene (47.6 mmol). The weight average molecular weights of the central block (polyisobutylene) and the whole block copolymer as well as the glass transition temperature are measured in the same manner as in Example 2. These data are collated in Table III, below. after.

EXAMPLE 8 Preparation of a Polymer Based on a Cutting of Block Copolymers Usable in the Pneumatic Object According to the Invention (Polymer 7) Block copolymer R-pinene / styrene / isobutylene / styrene / 13-pinene and isobutylene / styrene / 13-pinene block copolymer (40% by weight of diblock copolymer versus triblock copolymer) Polymer 7 is prepared in the same manner as polymer 3, with different amounts for the following species: hexane (4630 mmol); butyl chloride (23186 mmol); isobutylene (6130 mmol); p-dicumyl chloride (1.72 mmol); cumyl chloride (2.29 mmol); a-picoline (91.2 mmol); titanium tetrachloride (198 mmol); styrene (1178 mmol); 13-pinene (134 mmol). The weight average molecular weights of the central blocks (polyisobutylene) and the second entire block copolymer (that comprising two thermoplastic blocks) as well as the glass transition temperature of the elastomeric blocks of the diblock copolymer and the triblock copolymer are measured in the same way. as in Example 3. These data are collated in Table III, hereinafter. Table III This table collects the weight average molecular weight values (Mw) of the block copolymer alone (for reference 6) or the second block copolymer (for reference 7), the units of 13-pinene levels. of the block copolymer alone (for reference 6) or in the mixture (for reference 7) in moles relative to the number of moles of units of the block copolymer alone (for reference 6) or of the mixture (for the reference 7) (% 13-pinene), the percentage by weight of the thermoplastic block (s) in the block copolymer alone (for reference 6) or in the mixture (for reference 7) (% TP blocks), the percentage in the weight of the first block copolymer (diblock copolymer) relative to the weight of the second block copolymer (triblock copolymer) (% diblock) and the glass transition temperature of the elastomeric blocks of the block-only copolymer (for reference 6) or elastomeric blocks of the m mixture (for reference 7). In the case of mixing, the value of the glass transition temperature is the same whether the copolymers are diblock or triblock. (Ref.) (Inv.) Mw (in 150 120 kg / mol)% P-pinene 3.1 1.9% TP blocks 20 20% diblocks 0 40 Tg -58 ° C -57 ° C elastomer Example 9 : Preparation and evaluation of inflation-gas-tight elastomeric layer Polymers 6 and 7 previously described are also used to prepare gas-tight layers (layers 6 and 7). These layers are prepared from the ingredients and contents of Table IV below. The sealed elastomeric thermoplastic layers of the invention are prepared conventionally, for example, by incorporating the various components into a twin-screw extruder, so as to effect die fusion and incorporation of all the ingredients, then use of a flat die for producing the thermoplastic layer. More generally, the shaping of the thermoplastic can be made by any method known in the art: extrusion, calendering, extrusion blow molding, injection, cast film. TABLE IV Layer 6 Layer 7 Polymer 6 100 phr - Polymer 7 - 100 phr 67 pce oil 67 pces extension (Indopol GDP) Charge 27 pce 27 phr (SYA21R from Yamaguchi) The properties of these impervious layers were then evaluated. The data are collated in Table V below.

Table V This table collects the normalized values (relative to layer 1 of Table II) of the sealing, adhesion and heat resistance of the elastomeric layers prepared using the polymers previously synthesized above. Sealing Adhesion Layer 6 81 120 Layer 7 102 320 3033571 44 The comparison of the sealing performance of the usable layer according to the invention 7 and of the comparative layer 6 shows that the absence of blending of block copolymers adversely affects the sealing performance while the presence of a cut allows to improve the seal while leading to a much better adhesion performance.

Claims (28)

REVENDICATIONS1. A pneumatic object provided with an elastomeric layer that is impervious to inflation gases, said elastomer layer predominantly comprising a blend of the following two thermoplastic elastomers: a) a first thermoplastic elastomer in the form of a first block copolymer which comprises a first elastomeric block comprising at least one least units derived from isobutylene, and having a glass transition temperature of less than or equal to -20 ° C, connected at one of its ends to a first thermoplastic block, said first thermoplastic block comprising at least a first block consisting of units derived from at least one first polymerizable monomer and at least one second block consisting of units derived from 13-pinene, b) a second thermoplastic elastomer in the form of a second block copolymer which comprises a second elastomeric block comprising at least units derived from isobutylene, and having a vitreous transition temperature e less than or equal to -20 ° C, connected at each of its two ends to second thermoplastic blocks, said second thermoplastic blocks each comprising at least a first block consisting of units from at least one second polymerizable monomer and at least a second block consisting of units from 13-pinene. 2. Object according to claim 1, characterized in that the first polymerizable monomer or monomers are selected from styrenic monomers, and preferably the first polymerizable monomer is styrene. 3. Object according to claim 1 or 2, characterized in that the second or more polymerizable monomers are selected from styrenic monomers, and preferably the second polymerizable monomer is styrene. 3033571 46 4. Object according to any one of the preceding claims, characterized in that the first block copolymer has a weight average molecular weight ranging from 15 to 150 kg / mol, preferably from 60 to 125 kg / mol. 5 5. Object according to any one of the preceding claims, characterized in that the second block copolymer has a weight average molecular weight ranging from 30 to 300 kg / mol, preferably from 120 to 250 kg / mol. 6. Object according to any one of the preceding claims, characterized in that the level of units derived from P-pinene in the first block copolymer varies from 0.5 to 10 mol%, preferably from 1 to 5 mol%, based on the number of moles of units of the first block copolymer. 7. Object according to any one of the preceding claims, characterized in that the level of units derived from P-pinene in the second block copolymer varies from 0.5 to 10 mol%, preferably from 1 to 5. mol%, based on the number of moles of units of the second block copolymer. 8. Object according to any one of the preceding claims, characterized in that the first thermoplastic block represents from 5 to 30% by weight, preferably from 10 to 25% by weight, relative to the total weight of the first block copolymer . 9. Object according to any one of the preceding claims, characterized in that the second thermoplastic blocks 25 represent 5 to 30% by weight, preferably 10 to 25% by weight, relative to the total weight of the second block copolymer . An article according to any one of the preceding claims, characterized in that the first elastomeric block has a glass transition temperature of less than or equal to -40 ° C, preferably less than or equal to -50 ° C. 11. Object according to any one of the preceding claims, characterized in that the second elastomer block has a glass transition temperature of less than or equal to -40 ° C, preferably less than or equal to -50 ° C. 3033571 47 12. Object according to any one of the preceding claims, characterized in that the first elastomer block comprises from 0.5 to 6% by weight of units derived from one or more first conjugated dienes, preferably from 1.5 to 5% by weight, based on the total weight of the first elastomer block. 13. Object according to any one of the preceding claims, characterized in that the second elastomer block comprises from 0.5 to 6% by weight of units derived from one or more second conjugated dienes, preferably from 1.5 to 5% by weight, based on the total weight of the second elastomer block. 14. Object according to claim 12 or 13, characterized in that the first conjugated dienes and / or the second conjugated dienes or are chosen from isoprene, 1,3-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, Methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene, 2,3-dimethyl-1,3-pentadiene, 1,3-hexadiene, 2-methyl-1,3-hexadiene 3-methyl-1,3-hexadiene, 4-methyl-1,3-hexadiene, 5-methyl-1,3-hexadiene, 2,3-dimethyl-1,3-hexadiene, 2, 4-dimethyl-1,3-hexadiene, 2,5-dimethyl-1,3-hexadiene, 2-neopentylbutadiene, 1,3-cyclopentadiene, 1,3-cyclohexadiene, 1-vinyl-1, 3-cyclohexadiene, and mixtures thereof. 15. Object according to any one of the preceding claims, characterized in that the first block copolymer represents from 5 to 35% by weight, preferably from 10 to 30% by weight, relative to the weight of the second block copolymer. . 16. Object according to any one of the preceding claims, characterized in that the elastomeric layer impervious to inflation gases further comprises an extension oil. 30 An article according to claim 16, characterized in that the extender oil is chosen from the group consisting of polyolefinic oils, paraffinic oils, naphthenic oils, aromatic oils, mineral oils and mixtures of these oils. . 3033571 48 18. Object according to claim 17, characterized in that the extender oil is selected from olefinic oils, and preferably is a polyisobutylene oil. 19. Object according to any one of claims 16 to 18, characterized in that the extension oil has a number-average molar mass ranging from 350 to 4000 g / mol, preferably ranging from 400 to 3000 g / ml. mol. 20. Object according to any one of claims 16 to 19, characterized in that the extension oil has a content greater than 10 5 phr, preferably between 5 and 100 phr. 21. Object according to any one of the preceding claims, characterized in that the elastomeric layer impervious to inflation gases has a thickness greater than or equal to 0.05 mm, preferably ranging from 0.1 to 10 mm, and more preferably ranging from 0.1 to 2 mm. 22. Object according to any one of the preceding claims, characterized in that the elastomeric layer impervious to inflation gases is disposed on the inner wall of the pneumatic object. 20 23. Object according to any one of the preceding claims, characterized in that said object is a tire. 24. A process for sealing a pneumatic object with respect to inflation gases, in which is incorporated in said pneumatic object 25 during its manufacture, or is added to said pneumatic object after its manufacture, an elastomeric layer impervious to inflation gases such as as defined in any one of claims 1 to 21. 25. The method of claim 24, characterized in that the elastomeric airtight layer is deposited on the inner wall of the pneumatic object. 26. The method of claim 24 or 25, characterized in that the object is a tire. 27. A method according to claim 26, characterized in that during a first step, the inflation-gas-tight elastomeric layer is deposited flat on a building drum, before covering said gas-tight elastomeric layer. inflating the rest of the tire structure. 28. Use as an air-tight layer, in a pneumatic object, of an elastomeric layer as defined in any one of claims 1 to 21.