CN112243452A

CN112243452A - Tire having an outer sidewall comprising one or more thermoplastic elastomers and one or more synthetic diene elastomers

Info

Publication number: CN112243452A
Application number: CN201980036719.1A
Authority: CN
Inventors: D·冈萨雷斯; C·舒韦尔
Original assignee: Compagnie Generale des Etablissements Michelin SCA
Current assignee: Compagnie Generale des Etablissements Michelin SCA
Priority date: 2018-05-31
Filing date: 2019-05-17
Publication date: 2021-01-19
Also published as: FR3081875A1; WO2019229325A3; WO2019229325A2; FR3081875B1

Abstract

The invention relates to a tire having an outer sidewall comprising a composition based on at least one elastomeric matrix comprising at least one diene elastomer chosen from butadiene polymers having a glass transition temperature of less than or equal to-50 ℃ and at least one thermoplastic elastomer comprising at least one elastomeric block and at least one thermoplastic block, wherein the elastomeric block comprises at least butadiene units and isoprene units, the elastomeric block being capable of being partially or fully hydrogenated, a crosslinking system and a reinforcing filler.

Description

Tire having an outer sidewall comprising one or more thermoplastic elastomers and one or more synthetic diene elastomers

Technical Field

The present invention relates to tires and more particularly to the outer sidewalls of tires, that is to say, by definition, to the elastomeric layers that are in contact with the ambient air, radially outside the tire.

Background

Three regions can be defined within the tire:

a radially outer zone in contact with the ambient air, this zone consisting essentially of the tread and the outer sidewall of the tire. The outer sidewalls are elastomeric layers located externally to the carcass reinforcement with respect to the inner cavity of the tire and between the crown and the beads, so as to completely or partially cover the region of the carcass reinforcement extending from the crown to the beads.

The radially inner region in contact with the inflation gas, which region is generally composed of a layer (sometimes called liner) that is gas-tight to the inflation gas.

The inner zone of the tyre, that is to say the zone between the outer zone and the inner zone. This region includes what is referred to herein as a layer or ply of the inner layer of the tire. Such layers or plies are for example carcass plies, undertread, tire belt plies or any other layer not in contact with the ambient air or inflation gas of the tire.

Compositions commonly used for sidewalls are based on natural rubber, synthetic rubber (for example polybutadiene), carbon black and ozone-resistant waxes, as described in a large number of documents, among which documents EP 1097966, EP 1462479, EP 1033265, EP 1357149, EP 1231080 and US 4824900 may be mentioned.

Tire sidewalls must have a number of other characteristics that are sometimes difficult to reconcile, particularly good ozone resistance, low hysteresis, and stiffness suitable for the outer sidewall of the tire.

In particular, ozone is known to have a deleterious effect on rubber articles, often causing blooming on the surface of these articles

And/or cracks. To eliminate these detrimental effects, anti-ozone waxes well known to those skilled in the art are typically used.

Therefore, there is also a need to minimize these phenomena, particularly without compromising other properties of the outer sidewall.

Disclosure of Invention

In the course of continuing research, the applicant company has developed a rubber composition for the outer sidewall of a tyre which confers to said outer sidewall an improved ozone resistance, a reduced hysteresis (synonymous with a better rolling resistance) with respect to the outer sidewalls of the prior art, by replacing all or part of the natural rubber of the composition with at least one specific thermoplastic elastomer.

The subject of the present invention is therefore a tire provided with an outer sidewall comprising a composition based on at least one elastomeric matrix comprising:

-at least one diene elastomer chosen from butadiene polymers having a glass transition temperature of less than or equal to-50 ℃, and

-at least one thermoplastic elastomer comprising at least one elastomer block comprising at least butadiene units and isoprene units and at least one thermoplastic block, said elastomer block being capable of being partially or fully hydrogenated.

The invention and its advantages will be readily understood from the following description and examples.

Detailed Description

I-definition of

Within the meaning of the present invention, the expression "parts by weight per hundred parts by weight of elastomer" (or phr) is understood to mean parts by weight per hundred parts by weight of elastomer (whether it is a thermoplastic elastomer or not). In other words, the thermoplastic elastomer is an elastomer.

In the present application, all percentages (%) shown are percentages by weight (%), unless explicitly stated otherwise.

Furthermore, any numerical interval denoted by the expression "between a and b" denotes a range of values extending from more than a to less than b (i.e. not including the limits a and b), whereas any numerical interval denoted by the expression "from a to b" denotes a range of values extending from a up to b (i.e. including the strict limits a and b). In the present application, when numerical intervals are indicated by the expression "from a to b", it is also preferable to indicate intervals indicated by the expression "between a and b".

In the present application, the expression composition "based on" is understood to mean that the composition comprises a mixture and/or a reaction product of the various components used, some of which are capable of (and/or intended to) at least partially react with each other during the various manufacturing stages of the composition.

When referring to a "primary" compound, it is understood within the meaning of the present invention to mean that, among the compounds of the same type in the composition, this compound is primary, i.e. the compound which makes up the greatest amount by weight among the compounds of the same type, for example, more than 50%, 60%, 70%, 80%, 90%, even 100% by weight relative to the total weight of the compound type. Thus, for example, the predominant reinforcing filler is the reinforcing filler present in the greatest weight relative to the total weight of reinforcing fillers in the composition.

In the context of the present invention, the carbon-containing compounds mentioned in the description may be compounds of fossil or biological origin. In the case of biological origin, it may be partially or completely derived from biomass or obtained by renewable starting materials derived from biomass. In particular to polymers, plasticizers, fillers, and the like.

Unless otherwise indicated, the components described in this application form part of the outer sidewall composition of the tire according to the invention. Their respective incorporation levels correspond to their content in the outer sidewall composition of the tire according to the invention. Thus, when the expression "composition" is used, unless otherwise indicated, reference is made to the outer sidewall composition of the tire according to the invention.

All values of glass transition temperature "Tg" described in the present application are measured by DSC (differential scanning calorimetry) in a known manner according to the standard ASTM D3418 (1999).

II-detailed description of the invention

II-1 elastomeric matrix

The elastomeric matrix of the outer sidewall composition of the tire according to the invention comprises at least one diene elastomer chosen from butadiene polymers having a glass transition temperature of less than or equal to-50 ℃ and at least one thermoplastic elastomer comprising at least one elastomeric block comprising at least butadiene units and isoprene units, said elastomeric block being capable of being partially or fully hydrogenated.

II-1-a diene elastomer

According to the invention, the elastomeric matrix comprises at least one diene elastomer chosen from butadiene polymers having a glass transition temperature (Tg) of less than or equal to-50 ℃.

Diene elastomer is understood in a known manner to be an elastomer derived at least in part from diene monomers (i.e. a homopolymer or a copolymer). In a manner known per se, diene monomers are monomers which comprise two conjugated or non-conjugated carbon-carbon double bonds.

Thus, a diene elastomer chosen from butadiene polymers is understood to mean an elastomer derived at least in part (i.e. a homopolymer or a copolymer) from butadiene monomers.

Preferably, the diene elastomer chosen from butadiene polymers having a glass transition temperature of less than or equal to-50 ℃ is chosen from homopolymers obtained by polymerization of butadiene monomers, copolymers obtained by copolymerization of one or more conjugated diene monomers, at least one of which is a butadiene monomer, with each other or with one or more vinyl aromatic compounds having from 8 to 20 carbon atoms, and mixtures of these polymers (it being understood that the glass transition temperatures (Tg) of these elastomers are all less than or equal to-50 ℃).

The following are particularly suitable as conjugated dienes: 1, 3-butadiene, 2-methyl-1, 3-butadiene, 2, 3-di (C)₁-C₅Alkyl) -1, 3-butadiene (for example 2, 3-dimethyl-1, 3-butadiene, 2, 3-diethyl-1, 3-butadiene, 2-methyl-3-ethyl-1, 3-butadiene or 2-methyl-3-isopropyl-1, 3-butadiene) or aryl-1, 3-butadiene.

For example, the following are suitable as vinylaromatic compounds: styrene, o-, m-or p-methylstyrene, "vinyltoluene" commercial mixtures, p- (tert-butyl) styrene, methoxystyrene, chlorostyrene, vinylmesitylene, divinylbenzene or vinylnaphthalene.

When the diene elastomer chosen from butadiene polymers having a glass transition temperature of less than or equal to-50 ℃ is chosen from copolymers obtained by copolymerization of one or more conjugated dienes, at least one of which is a butadiene monomer, with each other or with one or more vinyl aromatic compounds having from 8 to 20 carbon atoms, these copolymers may comprise between 99% and 20% by weight of butadiene units and between 1% and 80% by weight of vinyl aromatic units. In this case, the butadiene polymer having a glass transition temperature of less than or equal to-50 ℃ preferably has between 1% and 50% by weight, more preferably between 0% and 10% by weight, of vinyl aromatic units.

The diene elastomer selected from butadiene polymers having a glass transition temperature of less than or equal to-50 ℃ which can be used according to the invention can have any microstructure depending on the polymerization conditions used, in particular the presence or absence and the amount of modifier and/or randomizer used.

The diene elastomers selected from butadiene polymers having a glass transition temperature of less than or equal to-50 ℃ which can be used according to the invention can be prepared, for example, in dispersion or in solution; which may be coupled and/or star branched or functionalized with coupling agents and/or star branching or functionalizing agents. For coupling with carbon black, mention may be made, for example, of functional groups comprising a C-Sn bond or aminated functional groups (such as benzophenones); for coupling to reinforcing inorganic fillers (e.g. silica), mention may be made, for example, of silanol functional groups or polysiloxane functional groups having a silanol end-capping (e.g. the polysiloxane functional groups described in FR 2740778 or US 6013718), alkoxysilane groups (e.g. the alkoxysilane groups described in FR 2765882 or US 5977238), carboxyl groups (e.g. the carboxyl groups described in WO 01/92402 or US 6815473, WO 2004/096865 or US 2006/0089445) or polyether groups (e.g. the polyether groups described in EP 1127909 or US 6503973).

Mention may also be made, as other examples of functionalized elastomers, of elastomers of the epoxidized type (for example SBR or BR).

The following are particularly suitable as diene elastomers chosen from butadiene polymers having a glass transition temperature of less than or equal to-50 ℃ which can be used in the composition of the outer sidewall of the tire according to the invention: polybutadiene having a content of 1,2 units (mol%) of between 4% and 80% or polybutadiene having a content of cis-1, 4 units (mol%) of more than 80%, butadiene/styrene copolymers, in particular butadiene/styrene copolymers having a glass transition temperature Tg (measured according to ASTM D3418(1999) of between-50 ℃ and-70 ℃, more particularly between-50 ℃ and-60 ℃, a styrene content of between 5% and 60% by weight, more particularly between 20% and 50%, a 1, 2-linkage content of the butadiene moiety (mol%) of between 4% and 75%, a trans-1, 4-linkage content (mol%) of between 10% and 80%), butadiene/isoprene copolymers, in particular butadiene/isoprene co-copolymers having an isoprene content of between 5% and 90% and a Tg of between-50 ℃ and-80 ℃ A polymer). In the case of butadiene/styrene/isoprene copolymers, particularly suitable are those having a styrene content of between 5% and 50% by weight, more particularly between 10% and 40%, an isoprene content of between 15% and 60% by weight, more particularly between 20% and 50%, a butadiene content of between 5% and 50% by weight, more particularly between 20% and 40%, a 1, 2-unit content (mol%) of the butadiene moiety of between 4% and 85%, a trans-1, 4-unit content (mol%) of the butadiene moiety of between 6% and 80%, a 1, 2-plus 3, 4-unit content (mol%) of the isoprene moiety of between 5% and 70%, a trans-1, 4-unit content (mol%) of the isoprene moiety of between 10% and 50%, more typically any butadiene/styrene/isoprene copolymer having a Tg between-70 ℃ and-50 ℃.

In a particularly preferred manner, the diene elastomer chosen from butadiene polymers having a glass transition temperature of less than or equal to-50 ℃ is chosen from polybutadiene (abbreviated to "BR"), butadiene copolymers (preferably butadiene/styrene copolymers (SBR), isoprene/butadiene copolymers (BIR) and isoprene/butadiene/styrene copolymers (SBIR)) and mixtures thereof (it being understood that these elastomers all have a glass transition temperature (Tg) of less than or equal to-50 ℃).

Also preferably, the diene elastomer selected from butadiene polymers having a glass transition temperature of less than or equal to-50 ℃ is selected from polybutadiene, butadiene/styrene copolymers and mixtures of these elastomers (it being understood that these elastomers each have a glass transition temperature (Tg) of less than or equal to-50 ℃).

Preferably, the content of diene elastomer selected from butadiene polymers having a glass transition temperature of less than or equal to-50 ℃ which may be used in the composition for the sidewall of the tire according to the invention is in the range from 50phr to 99phr, preferably from 55phr to 95phr, more preferably from 60phr to 90phr, still more preferably from 65phr to 85 phr.

II-1-b thermoplastic elastomer

According to the invention, the elastomer matrix comprises at least one thermoplastic elastomer comprising at least one elastomer block comprising at least butadiene units and isoprene units and at least one thermoplastic block, said elastomer block being capable of being partially or fully hydrogenated.

In the present application, when reference is made to "thermoplastic elastomer", it is intended, unless otherwise stated, to at least one thermoplastic elastomer comprising at least one elastomeric block comprising at least butadiene units and isoprene units, and at least one thermoplastic block, said elastomeric block being capable of being partially or completely hydrogenated.

Thermoplastic elastomer (TPE) is understood in a known manner to mean a polymer having a structure between a thermoplastic polymer and an elastomer. Thermoplastic elastomers are formed from one or more rigid "thermoplastic" segments joined to one or more flexible "elastomeric" segments.

Thus, the thermoplastic elastomer of the composition of the outer sidewall that can be used according to the present invention comprises at least one elastomeric block and at least one thermoplastic block.

Thus, a composition of a mixed resin or thermoplastic polymer and elastomer does not constitute a thermoplastic elastomer within the meaning of the present invention.

Typically, each of these segments or blocks comprises at least greater than 5, and often greater than 10, base units.

In this patent application, when referring to the glass transition temperature of a thermoplastic elastomer, it is the glass transition temperature associated with the elastomer block (unless otherwise stated). This is because, in a known manner, thermoplastic elastomers exhibit two glass transition temperature (Tg, measured according to ASTM D3418 (1999)) peaks or one Tg peak (the elastomer part of the thermoplastic elastomer) and one melting point peak (the thermoplastic part of the thermoplastic elastomer) (Tf, measured by DSC in a known manner according to standard ASTM D3418). When the thermoplastic elastomer exhibits 2 Tg peaks, the lowest temperature is associated with the elastomer portion of the thermoplastic elastomer and the highest temperature is associated with the thermoplastic portion of the thermoplastic elastomer. Thus, the flexible block of the thermoplastic elastomer is generally defined by a Tg of less than or equal to ambient temperature (25 ℃) while the rigid block has a Tg of greater than or equal to 80 ℃. In order to have both elastomeric and thermoplastic properties, the thermoplastic elastomer must be provided with sufficiently incompatible blocks (that is to say, different due to their respective weights, their respective polarities or their respective Tg values) to retain the nature of its own elastomeric block or the nature of the thermoplastic block.

Preferably, the glass transition temperature of the elastomer block of the thermoplastic elastomer is less than or equal to-50 ℃, preferably less than-60 ℃.

It is also preferred that the thermoplastic elastomers that can be used according to the invention (i.e. the elastomer blocks of the thermoplastic elastomer) have a glass transition temperature of more than-100 ℃.

The number average molecular weight (expressed as Mn) of the thermoplastic elastomer is preferably between 30000g/mol and 500000g/mol, more preferably between 40000g/mol and 400000g/mol, still more preferably between 50000g/mol and 300000 g/mol. Below the minimum indicated, there is a risk that the cohesion between the elastomer chains of the thermoplastic elastomer is affected, in particular due to its possible dilution (in the presence of extender oil); furthermore, there is a risk that an increase in the working temperature affects the mechanical properties (in particular the fracture properties), with the consequence of a reduction in the "thermal" performance. In addition, too high Mn may be detrimental to processing.

The number-average molecular weight (Mn) of the thermoplastic elastomer is determined in a known manner by Size Exclusion Chromatography (SEC). The sample was dissolved in a suitable solvent in advance at a concentration of about 2g/L, and then the solution was filtered through a filter having a porosity of 0.45 μm before injection. The device used was a Waters Alliance chromatogram. The injection volume of the polymer sample solution was 100. mu.L. The detector was a Waters 2410 differential refractometer, and the associated software for using the chromatographic data was the Empower system. The conditions can be adjusted by those skilled in the art. For example, in the case of the COPE type TPE, the elution solvent was hexafluoroisopropanol with sodium trifluoroacetate concentration of 0.02M, flow rate was 0.5mL/min, system temperature was 35 ℃ and analysis time was 90 min. A series of three Phenomenex columns (pore size: 105, 104, 103A) under the trade designation "Phenogel" were used. For example, in the case of a thermoplastic styrene elastomer, a sample was dissolved in tetrahydrofuran in advance at a concentration of about 1g/L, and then the solution was filtered through a filter having a porosity of 0.45 μm before injection. The device used was a Waters Alliance chromatogram. The elution solvent was tetrahydrofuran, the flow rate was 0.7mL/min, the system temperature was 35 ℃ and the analysis time was 90 min. A set of four Waters columns in series with the trade names Styragel (HMW7, HMW6E and two HT6E) was used. The injection volume of the polymer sample solution was 100. mu.L. The detector was a Waters 2410 differential refractometer, and the associated software for using the chromatographic data was a Waters Millennium system. The calculated average molar mass is relative to a calibration curve generated with polystyrene standards.

The polydispersity index (PI ═ Mw/Mn, where Mw is the weight average molecular weight) of the thermoplastic elastomer is preferably less than 3, more preferably less than 2, and still more preferably less than 1.5.

The thermoplastic elastomers which can be used according to the invention are advantageously copolymers having a small number (less than 5, usually 2 or 3) of blocks, in which case these blocks preferably have a high weight/mass of more than 15000 g/mol.

The thermoplastic elastomers which can be used according to the invention are advantageously provided in linear form.

The thermoplastic elastomer may in particular be a diblock copolymer: thermoplastic block/elastomer block. It may also be a triblock copolymer: thermoplastic block/elastomer block/thermoplastic block, i.e., a middle elastomer block and a terminal thermoplastic block at each of the two ends of the elastomer block. Also suitable as thermoplastic elastomers are mixtures of the triblock copolymers and diblock copolymers described in this application. This is because the triblock copolymer may contain a minor weight fraction of diblock copolymer consisting of rigid styrene segments and flexible diene segments, and the rigid and flexible blocks have the same chemical characteristics, in particular the same microstructure, as the rigid and flexible blocks of the triblock, respectively. The diblock copolymer present in the triblock copolymer is typically produced by a process of synthesis of the triblock copolymer that can result in the formation of by-products (e.g., diblock copolymer). Typically, the percentage of diblock copolymer in the triblock copolymer does not exceed 40 wt.% of the triblock copolymer.

The thermoplastic elastomer may also be formed from a linear sequence of elastomer blocks and thermoplastic blocks (multiblock thermoplastic elastomers).

The thermoplastic elastomers which can be used according to the invention can also be provided in the form of star-branches comprising at least three branches.

For example, the thermoplastic elastomer may consist of a star-branched elastomer block comprising at least three branches and a thermoplastic block located at the end of each branch of the elastomer block. For example, the number of branches of the intermediate elastomer may vary from 3 to 12, preferably from 3 to 6.

Particularly advantageously, the thermoplastic elastomer comprises two identical or different (preferably identical) thermoplastic blocks separated by at least one elastomeric block.

As previously mentioned, the thermoplastic elastomer which can be used according to the invention comprises at least one elastomeric block comprising at least butadiene units and isoprene units and at least one thermoplastic block, the elastomeric block being capable of being partially or fully hydrogenated.

The weight fraction of isoprene units of the elastomer block of the thermoplastic elastomer is advantageously in the range from 40% to 80%, preferably from 50% to 70%, more preferably from 55% to 65%.

Advantageously, the elastomeric blocks do not represent one or more polyisobutylene blocks. Within the meaning of the present invention, "polyisobutene block" is understood as meaning a block which consists predominantly of polymerized isobutene monomers. Advantageously, therefore, the thermoplastic elastomer is not a styrene/polyisobutylene/styrene (SIBS) copolymer.

The butadiene units of the elastomer block of the thermoplastic elastomer are advantageously 1, 3-butadiene units.

The weight fraction of butadiene units of the elastomer block of the thermoplastic elastomer is advantageously in the range from 20% to 60%, preferably from 30% to 50%, more preferably from 35% to 45%.

Particularly advantageously, the elastomeric block of the thermoplastic elastomer is a random copolymer of butadiene units and isoprene units.

The elastomer block of the thermoplastic elastomer may additionally comprise units other than butadiene units and isoprene units.

In particular, the monomers polymerized to form the elastomeric block of the thermoplastic elastomer may be randomly copolymerized with at least one other monomer to form the elastomeric block. According to this alternative form, the molar fraction of the other polymerized monomers, with respect to the total number of units of the elastomeric block, must be such that the block retains its elastomeric properties. Advantageously, the molar fraction of this other comonomer can range from 0% to 50%, more preferably from 0% to 30%, still more preferably from 0% to 10%.

As an example, this other monomer which is copolymerizable with the first monomer may be selected from ethylenic monomers (e.g. ethylene or propylene), monomers of the vinylaromatic type having from 8 to 20 carbon atoms, as defined below, or it may be a monomer such as vinyl acetate.

Styrene monomers, i.e.methylstyrene, p- (tert-butyl) styrene, chlorostyrene, bromostyrene, fluorostyrene or p-hydroxystyrene, are particularly suitable as vinylaromatic compounds. Preferably, the comonomer of the vinylaromatic type is styrene.

Thus, the elastomer block of the thermoplastic elastomer may additionally comprise vinylaromatic units, preferably styrenic units, preferably styrene units.

In the present description, styrenic units are understood to mean any unit comprising unsubstituted or substituted styrene; among the substituted styrenes, mention may be made, for example, of methylstyrene (for example, o-methylstyrene, m-methylstyrene or p-methylstyrene, α, 2-dimethylstyrene, α, 4-dimethylstyrene or diphenylethylene), p- (tert-butyl) styrene, chlorostyrene (for example, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, 2, 4-dichlorostyrene, 2, 6-dichlorostyrene or 2,4, 6-trichlorostyrene), bromostyrene (for example, o-bromostyrene, m-bromostyrene, p-bromostyrene, 2, 4-dibromostyrene, 2, 6-dibromostyrene or 2,4, 6-tribromostyrene), fluorostyrene (for example, o-fluorostyrene, m-fluorostyrene, p-fluorostyrene, 2, 4-difluorostyrene), fluorostyrene, 2, 6-difluorostyrene or 2,4, 6-trifluorostyrene) or p-hydroxystyrene.

The mole fraction of styrenic units of the elastomer block of the thermoplastic elastomer may range from greater than 0% to 30% (e.g., from greater than 0% to 10%), preferably from greater than 0% to 5%.

Advantageously, the number average molecular weight (Mn) of the elastomeric blocks of the thermoplastic elastomer is in the range from 25000g/mol to 350000g/mol, preferably from 35000g/mol to 250000 g/mol. This weight range can impart to the thermoplastic elastomer good elastic properties and sufficient mechanical strength that is compatible with use as an outer sidewall of a tire.

The elastomer block of the thermoplastic elastomer may not be hydrogenated.

Alternatively, the elastomer block of the thermoplastic elastomer may be partially hydrogenated or fully hydrogenated, preferably partially hydrogenated.

Preferably, in the thermoplastic elastomer used in the requirements of the present invention, the elastomer block may be hydrogenated in such a manner that the proportion of double bonds in the butadiene portion is in the range of 10 to 90 mol%, preferably 50 to 80 mol%.

The degree of hydrogenation was determined by NMR analysis. Spectra were collected on a Bruker Avance 500MHz spectrometer equipped with a 5mm 1H-X cryoprobe. Quantification of¹H NMR experiments used a simple 30 ° pulse sequence and a repetition time of 5 seconds between each acquisition. 64 accumulations were made. The sample (about 25mg) was dissolved in about 1mL of CS₂Performing the following steps; 100 μ L of deuterated cyclohexane was added during collection to form locks. Reference TMS (at 0ppm¹H δ ppm) relative to CS at 7.18ppm₂ ¹Protonated impurities at H δ ppm calibrate chemical shifts.¹H NMR spectra can quantify the microstructure by integration of broad, unresolved peaks of the characteristic signals of the different units:

styrene derived from polystyrene blocks and SBR. It can be quantified in the region of the aromatic compounds between 6.0ppm and 7.3ppm for 5 protons (minus CS at 7.18 ppm)₂Integration of the signal of the impurity).

1,2-PB originating from SBR. It can be quantified in the alkene region between 4.6ppm and 5.1ppm for 2 protons.

1,4-PB originating from SBR. It can be quantified in the alkene region between 5.1ppm and 6.1ppm for 2 protons, and 1 proton of the 1,2-PB unit is deleted.

Hydrogenated 1,2-PB originating from hydrogenation and having only aliphatic protons. Hydrogenation of the side group CH of 1,2-PB₃Can be identified and quantified in the aliphatic region between 0.4ppm and 0.8ppm for 3 protons.

Hydrogenated 1,4-PB, originating from hydrogenation and having only aliphatic protons. Considering that it is for 8 protons, it is derived by subtracting the aliphatic protons of each unit.

The microstructure can be quantified (in mole%) by: molar% of units being units¹H-integrate/sigma (per cell¹H integral). For example, for styrene units: molar% of styrene ═ of styrene¹Integral of H)/(styrene¹Of H integral +1,2-PB¹Of H integral +1,4-PB¹Of H integral + hydrogenated 1,2-PB¹Of H integral + hydrogenated 1,4-PB¹H integral).

As mentioned above, the thermoplastic elastomers which can be used according to the invention comprise at least one thermoplastic block.

Thermoplastic block is understood to mean a block formed by polymerizing monomers and having a glass transition temperature (or melting point in the case of semi-crystalline polymers) greater than or equal to 80 ℃, preferably ranging from 80 ℃ to 250 ℃, more preferably ranging from 80 ℃ to 200 ℃, in particular ranging from 80 ℃ to 180 ℃.

This is because, in the case of semi-crystalline polymers, melting points above the glass transition temperature can be observed. In this case, the melting point is considered in the above definition rather than the glass transition temperature.

The thermoplastic block can be formed from polymerized monomers of various characteristics.

In particular, the thermoplastic block of the thermoplastic elastomer may be selected from polyolefins (preferably polyethylene, polypropylene or mixtures thereof), polyurethanes, polyamides, polyesters, polyacetals, polyethers (preferably polyethylene oxide, polyphenylene oxide or mixtures thereof), polyphenylene sulfides, polyfluorinated compounds (preferably FEP, PFA, ETFE or mixtures thereof), polystyrenes, polycarbonates, polysulfones, poly (methyl methacrylate), polyetherimides, thermoplastic copolymers (for example acrylonitrile/butadiene/styrene (ABS) copolymers) and mixtures of these polymers.

Particularly preferably, in the present invention, the thermoplastic blocks of the thermoplastic elastomer are chosen from polystyrene, polyesters, polyamides, polyurethanes and mixtures of these polymers.

Very particularly preferably, in the context of the present invention, the thermoplastic blocks are chosen from polystyrenes, polyesters, polyamides and mixtures of these polymers.

More preferably, the thermoplastic block is selected from polystyrene.

As for polystyrene, it is obtained by styrene monomer.

In the present specification, styrene monomer is understood to mean any monomer comprising unsubstituted or substituted styrene; among the substituted styrenes, mention may be made, for example, of methylstyrene (for example, o-methylstyrene, m-methylstyrene or p-methylstyrene, α, 2-dimethylstyrene, α, 4-dimethylstyrene or diphenylethylene), p- (tert-butyl) styrene, chlorostyrene (for example, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, 2, 4-dichlorostyrene, 2, 6-dichlorostyrene or 2,4, 6-trichlorostyrene), bromostyrene (for example, o-bromostyrene, m-bromostyrene, p-bromostyrene, 2, 4-dibromostyrene, 2, 6-dibromostyrene or 2,4, 6-tribromostyrene), fluorostyrene (for example, o-fluorostyrene, m-fluorostyrene, p-fluorostyrene, 2, 4-difluorostyrene, p-fluorostyrene, 4-dichlorostyrene, p-fluorostyrene, 4-, 2, 6-difluorostyrene or 2,4, 6-trifluorostyrene) or p-hydroxystyrene.

Advantageously, the thermoplastic elastomer which can be used according to the invention has a styrene content by weight of between 5% and 50%, preferably between 10% and 40%, more preferably between 15% and 35%.

The thermoplastic block may also be obtained by monomers selected from:

-acenaphthylene: those skilled in the art can refer to articles such as z.fodor and j.p.kennedy, Polymer Bulletin, 1992, 29(6), 697-;

indene and its derivatives, such as 2-methylindene, 3-methylindene, 4-methylindene, dimethylindene, 2-phenylindene, 3-phenylindene and 4-phenylindene; those skilled in the art may refer to, for example, U.S. Pat. Nos. 4946899 and J.E.Puskas, G.Kaszas, J.P.Kennedy and W.G.Hager, the Journal of Polymer Science, Part A: Polymer Chemistry (1992), 30, 41 and Macromolecules (1991), 24(25), 6572) 6577, of the inventors Kennedy, Puskas, Kaszas and Hager;

isoprene, which then leads to the formation of a certain number of trans-1, 4-polyisoprene units and units cyclized according to intramolecular processes; those skilled in the art can refer to, for example, the documents Applied Polymer Science (1990), 39(1), 119-.

According to an alternative form of the invention, the above-mentioned monomers may be copolymerized with at least one other monomer, provided that said other monomer does not modify the thermoplastic characteristics of the block, that is to say that the glass transition temperature (or melting point in the case of semi-crystalline polymers) of said block is greater than or equal to 80 ℃.

On the one hand, the proportion of thermoplastic blocks in the thermoplastic elastomers which can be used according to the invention is determined by the thermoplastic properties which the thermoplastic elastomer must have.

The thermoplastic blocks are preferably present in a proportion sufficient to maintain the thermoplastic properties of the thermoplastic elastomers which may be used in accordance with the present invention. The minimum content of thermoplastic blocks in the thermoplastic elastomer may vary depending on the conditions under which the thermoplastic elastomer is used.

On the other hand, the deformability of the thermoplastic elastomer during the manufacture of the tire can also contribute to determining the proportion of thermoplastic blocks in the thermoplastic elastomer which can be used according to the invention.

Preferably, the number average molecular weight (Mn) of the thermoplastic block of the thermoplastic elastomer ranges from 5000g/mol to 150000g/mol, in order to impart to the thermoplastic elastomer good elastomeric properties and sufficient mechanical strength compatible with the use as an outer sidewall of a tire.

Particularly advantageously, the thermoplastic elastomer is chosen from styrene/butadiene/isoprene/styrene (SBIS) block copolymers, styrene/butadiene/isoprene (SBI) block copolymers and mixtures thereof.

As an example of a commercially available thermoplastic elastomer which can be used according to the invention, mention may be made of the SBIS type elastomer sold under the name D1170 by Kraton.

Preferably, the content of thermoplastic elastomer comprising at least one elastomeric block and at least one thermoplastic block (said elastomeric block comprising at least butadiene units and isoprene units, said elastomeric block being capable of being partially or fully hydrogenated) in the composition is in the range of from 1phr to 50phr, preferably from 5phr to 45phr, more preferably from 10phr to 40phr, still more preferably from 15phr to 35 phr.

Particularly preferably, the thermoplastic elastomer comprising at least one elastomeric block and at least one thermoplastic block (the elastomeric block comprising at least butadiene units and isoprene units, the elastomeric block being capable of being partially or fully hydrogenated) is the only thermoplastic elastomer in the elastomeric matrix.

II-1-c other Elastomers

The elastomeric matrix of the composition of the outer sidewall that can be used according to the invention may comprise diene elastomers or thermoplastic elastomers other than those selected from butadiene polymers having a glass transition temperature of less than or equal to-50 ℃ and thermoplastic elastomers comprising at least one elastomeric block comprising at least butadiene units and isoprene units and at least one thermoplastic block, said elastomeric block being capable of being partially hydrogenated or completely hydrogenated, but this is not essential or even preferred.

Advantageously, the composition of the outer sidewall that can be used according to the invention does not comprise other elastomers than diene elastomers chosen from butadiene polymers having a glass transition temperature of less than or equal to-50 ℃ and thermoplastic elastomers comprising at least one elastomeric block comprising at least butadiene units and isoprene units and at least one thermoplastic block, said elastomeric block being capable of being partially hydrogenated or completely hydrogenated, or comprises less than 20phr, preferably less than 10phr, more preferably less than 10phr of said other elastomers.

II-2 reinforcing fillers

The composition of the outer sidewall of the tire according to the invention additionally comprises reinforcing fillers known for their ability to reinforce rubber compositions that can be used for the manufacture of tires.

The reinforcing filler may include carbon black and/or silica. Advantageously, the reinforcing filler comprises mainly (preferably only) carbon black.

The carbon black that may be used in the context of the present invention may be any carbon black conventionally used in tires or treads therefor ("tire grade" carbon black). Among the "tire grade" blacks, mention will be made more particularly of reinforcing blacks of the series 100, 200 and 300 or blacks of the series 500, 600 or 700 (ASTM grades), such as, for example, the blacks N115, N134, N234, N326, N330, N339, N347, N375, N550, N683 and N772. These carbon blacks may be used in a commercially available stand-alone state or in any other form, for example as a carrier for some of the rubber additives used. The carbon black may, for example, have been incorporated into diene elastomers, in particular isoprene elastomers, in the form of a masterbatch (see, for example, applications WO 97/36724 or WO 99/16600).

As examples of organic fillers other than carbon black, mention may be made of functionalized polyvinyl organic fillers as described, for example, in applications WO 2006/069792, WO 2006/069793, WO 2008/003434 and WO 2008/003435.

Advantageously, the carbon black comprises predominantly (preferably exclusively) a BET specific surface of less than 70m²(preferably at 11 m)/g²G to 69m²In the range of/g), preferably less than 50m²A BET specific surface area of 11m is preferred²G to 49m²G, more preferably 21m²G to 49m²Carbon black in the range of/g.

The BET specific surface of the carbon black [ multipoint method (at least 5 points) -gas: nitrogen-relativePressure p/p_oThe range is as follows: 0.1 to 0.3]。

The silica which can be used in the context of the present invention may be any silica known to the person skilled in the art, in particular having a BET and CTAB specific surface both of which are less than 450m²A/g, preferably of 30m²G to 400m²(ii) any precipitated silica or fumed silica per gram.

The BET specific surface of The silica is determined in a known manner by gas adsorption using The Brunauer-Emmett-Teller method described in The Journal of The American Chemical Society (vol.60, p.309, month 2 1938), more particularly according to French Standard NF ISO 9277 (multipoint (5 points) volumetric method-gas: nitrogen-exhaust gas: 1 hour at 160 ℃ C. -relative pressure p/p) in 12 months 1996₀The range is as follows: 0.05 to 0.17). The CTAB specific surface of the silica was determined according to French standard NF T45-007 (method B) at 11 months 1987.

Preferably, the silica has less than 200m²A BET specific surface area of less than 220m²CTAB specific surface area/g, preferably 125m²G to 200m²BET specific surface in the range of/g and/or in the range of 140m²G to 170m²CTAB specific surface in the range of/g.

As silicas that can be used in the context of the present invention, mention will be made, for example, of the highly dispersible precipitated silicas from Evonik (known as "HDS") Ultrasil 7000 and Ultrasil 7005, the silicas Zeosil 1165MP, 1135MP and 1115MP from Rhodia, the silica Hi-Sil EZ150G from PPG, the silicas Zeopol 8715, 8745 and 8755 from Huber or the silicas with high specific surface area as described in application WO 03/16837.

For coupling the reinforcing silica to the diene elastomer, use is made, in a known manner, of an at least bifunctional coupling agent (or bonding agent) aimed at providing a linkage of satisfactory chemical and/or physical characteristics between the silica (on its particle surface) and the diene elastomer. In particular, at least bifunctional organosilanes or polyorganosiloxanes are used.

Examples of coupling agents can be found by those skilled in the art in the following references: WO 02/083782, WO 02/30939, WO 02/31041, WO 2007/061550, WO 2006/125532, WO 2006/125533, WO 2006/125534, US 6849754, WO 99/09036, WO 2006/023815, WO 2007/098080, WO 2010/072685 and WO 2008/055986.

Mention may in particular be made of alkoxysilane polysulfide compounds, in particular bis (trialkoxysilylpropyl) polysulfide, very particularly bis (3-triethoxysilylpropyl) disulfide (abbreviated to "TESPD") and bis (3-triethoxysilylpropyl) tetrasulfide (abbreviated to "TESPT"). It should be remembered that TESPD (formula [ (C)₂H₅O)₃Si(CH₂)₃S]₂) In particular sold by Degussa under the name Si266 or Si75 (in the second case in the form of a mixture of disulfides (75% by weight) and polysulfides). TESPT (chemical formula is [ (C)₂H₅O)₃Si(CH₂)₃S]₄) Sold in particular by Degussa under the name Si69 (or X50S when it is supported on carbon black at 50% by weight) and is the polysulfide S_x(wherein x has an average value of about 4).

The content of reinforcing filler in the composition is preferably in the range from 5phr to 70phr, preferably from 5phr to 55phr, more preferably from 5phr to 45 phr.

II-3 Cross-linking System

The system for crosslinking the composition of the outer sidewall of the tire according to the invention can be based on molecular sulfur and/or sulfur donors and/or peroxides, which are well known to the person skilled in the art.

The crosslinking system is preferably a vulcanization system based on sulfur (molecular sulfur and/or sulfur donor).

Sulphur is used in an amount preferably between 0.5phr and 10 phr. Advantageously, the sulphur content is between 0.5phr and 2phr, preferably between 0.5phr and 1.5phr, more preferably between 0.5phr and 1.4 phr.

The composition of the outer sidewall of the tyre according to the invention advantageously comprises a vulcanization accelerator, preferably selected from accelerators of the thiazole type and their derivatives, of the sulfenamide and thiourea type and mixtures thereof. Advantageously, the vulcanization accelerator is selected from the group consisting of 2-mercaptobenzothiazyl disulfide (MBTS), N-cyclohexyl-2-benzothiazylsulfenamide (CBS), N-dicyclohexyl-2-benzothiazylsulfenamide (DCBS), N- (tert-butyl) -2-benzothiazylsulfenamide (TBBS), N- (tert-butyl) -2-benzothiazylsulfenamide (TBSI), morpholine disulfide, N-morpholinyl-2-benzothiazylsulfenamide (MBS), Dibutylthiourea (DBTU) and mixtures thereof. Particularly preferably, the primary vulcanization accelerator is N-cyclohexyl-2-benzothiazolesulfenamide (CBS).

The content of vulcanization accelerator is preferably in the range from 0.2phr to 10phr, preferably from 0.2phr to 7phr, more preferably from 0.6phr to 2 phr.

Advantageously, the weight ratio of sulfur or sulfur donor/vulcanization accelerator varies from 0.8 to 1.2.

II-4 plasticizers

According to a preferred embodiment of the invention, the composition used in the outer sidewall of the tire according to the invention may also comprise at least one plasticizer, for example an oil (or plasticizing oil or extender oil) or a plasticizing resin, the function of which is to facilitate the processing of the outer sidewall (in particular its incorporation in the pneumatic article) by reducing the modulus and increasing the adhesion.

Any type of plasticizer may be used, which may be a plasticizing resin or a plasticizing oil. The expression "resin" denotes in the present patent application, according to a definition known to a person skilled in the art, a compound that is solid at ambient temperature (23 ℃), unlike a liquid plasticizing compound (for example, extender oil or plasticizing oil). At ambient temperature (23 ℃), these oils (more or less viscous) are liquids (to be reminded here, that is to say substances having the ability to finally assume the shape of their container), which is in particular different from resins or rubbers which are naturally solid.

Preferably, the plasticizing oil is selected from naphthenic oils (low or high viscosity, in particular hydrogenated or unhydrogenated), paraffinic oils, MES (medium extraction solvate) oils, TDAE (treated distilled aromatic extract) oils, RAE (residual aromatic extract) oils, TRAE (treated residual aromatic extract) oils, SRAE (safety residual aromatic extract) oils, mineral oils, vegetable oils, ether plasticizers, ester plasticizers, phosphate plasticizers, sulfonate plasticizers, liquid polymers and mixtures thereof. Preferably, the plasticizing oil is selected from naphthenic, paraffinic, MES, TDAE, RAE, TRAE, SRAE, mineral, liquid polymers and mixtures thereof, preferably selected from naphthenic, paraffinic, MES, TDAE, RAE, TRAE, SRAE, mineral and mixtures thereof.

The plasticizing oil preferably has a number-average molecular weight (Mn) of between 200g/mol and 25000g/mol, more preferably still between 300g/mol and 10000 g/mol. With too low Mn weight, there is a risk of oil migrating out of the composition, while too high a weight may result in the composition being too hard. Mn weights between 350g/mol and 4000g/mol, in particular between 400g/mol and 3000g/mol, have proved to constitute an excellent compromise for the intended application, in particular for use in the outer sidewalls of tires.

The number-average molecular weight (Mn) of the plasticizing oil was determined by Size Exclusion Chromatography (SEC), the sample having been dissolved beforehand in tetrahydrofuran at a concentration of about 1 g/L; the solution was then filtered through a filter with a porosity of 0.45 μm before injection. The device is a Waters Alliance color line. The elution solvent is tetrahydrofuran, the flow rate is 1mL/min, the system temperature is 35 ℃, and the analysis time is 30 min. A set of two Waters columns named Styragel HT6E was used. The injection volume of the polymer sample solution was 100. mu.L. The detector was a Waters 2410 differential refractometer, and the associated software for using the chromatographic data was a Waters Millennium system. The calculated average molar mass is relative to a calibration curve generated with polystyrene standards.

Advantageously, the plasticizing oil has a glass transition temperature of between-70 ℃ and-20 ℃, preferably between-68 ℃ and-40 ℃.

Preferably, therefore, the composition of the outer sidewall of the tire according to the invention does not comprise a liquid plasticizer having a glass transition temperature of less than-70 ℃. As an example of a liquid plasticizer having a glass transition temperature of less than-70 ℃, mention may be made of vegetable oils selected from sunflower oil, rapeseed oil and mixtures thereof.

As examples of plasticizing oils that can be used in the context of the present invention, mention may be made of MES oil Catenex SNR from Shell (Tg-65 ℃) or TDAE oil Vivatec 500 from Klaus Dahleke (Tg-48 ℃).

Hydrocarbon resins are polymers well known to those skilled in the art, which are essentially based on carbon and hydrogen and can be used in particular as plasticizers in elastomer compositions. It has been described, for example, in an article entitled "Hydrocarbon Resins" by R.Mildenberg, M Zander and G.Collin (New York, VCH, 1997, ISBN 3-527-. It may be aliphatic, cycloaliphatic, aromatic, hydroaromatic (i.e. based on aliphatic and/or aromatic monomers) of the aliphatic/aromatic type. It may be natural or synthetic, petroleum-based or not (in the case of petroleum-based, it is also known as petroleum resin). By definition, it is miscible (i.e. compatible) at the level used with the elastomeric composition for which it is used, thus acting as a true diluent. The Tg is preferably greater than 0 deg.C, in particular greater than 20 deg.C (most often between 30 deg.C and 120 deg.C).

In a known manner, hydrocarbon resins can also be described as thermoplastic resins, since they soften when heated and can therefore be moulded. It may also be defined by a softening point at which the products (e.g. in powder form) stick together. The softening point of hydrocarbon resins is generally about 50 ℃ to 60 ℃ higher than their Tg value.

As examples of such hydrocarbon resins, mention may be made of resins chosen from cyclopentadiene (abbreviated to CPD) or dicyclopentadiene (abbreviated to DCPD) homo-or copolymer resins, terpene/phenol homo-or copolymer resins, C₅Fraction homopolymer or copolymer resin, C₉A distillate homopolymer or copolymer resin, an alpha-methylstyrene homopolymer or copolymer resin, and mixtures of these resins. Among the above-mentioned copolymer resins, mention may be made more particularly of those selected from (D) CPD/vinyl aromatic copolymer resins, (D) CPD/terpene copolymer resins, (D) CPD/C₅A distillate copolymer resin, (D) CPD/C₅A distillate copolymer resin, (D) CPD/C₉Fractional copolymer resin, terpene/vinyl aromatic copolymer resin, terpene/phenol copolymer resin, C₅Distillate/vinyl aromatic copolymer resins and mixtures of these resins.

The term "terpene" herein gathers in a known manner the α -pinene, β -pinene and limonene monomers; preference is given to using limonene monomers, the compounds of which exist in a known manner in three possible isomeric forms: l-limonene (levo isomer), D-limonene (dextro isomer) or dipentene (racemate of levo and dextro isomers). Suitable vinylaromatic monomers are, for example, styrene, alpha-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluenes, p- (tert-butyl) styrene, methoxystyrenes, chlorostyrenes, hydroxystyrenes, vinylmesitylenes, divinylbenzene, vinylnaphthalenes or monomers derived from C₉Fraction (or more generally from C)₈To C₁₀Fractions) of any vinyl aromatic monomer.

More particularly, mention may be made of resins selected from (D) CPD homopolymer resin, (D) CPD/styrene copolymer resin, polycitratene resin, limonene/styrene copolymer resin, limonene/D (CPD) copolymer resin, C₅Fraction/styrene copolymer resin, C₅fraction/C₉Fraction copolymer resins and mixtures of these resins.

All the above plasticizing resins are well known to the person skilled in the art and are commercially available, for example the poly-limonene resin sold under the name Dercolyte by DRT, the Super Nevtac name by Neville Chemical Company, the Hikorez name by Kolon or the C sold under the name Escorez name by Exxon Mobil₅Fraction/styrene resin or C₅fraction/C₉Distillate resins, or sold under the name 40MS or 40NS by Struktol (mixture of aromatic and/or aliphatic resins).

When a plasticizer is used, the content of plasticizer in the composition of the outer sidewall of the tire according to the present invention is preferably in the range of 2phr to 60phr, preferably 3phr to 50phr, still more preferably 3phr to 20 phr. Below the minimum indicated, the presence of plasticizer is not evident. Above the recommended maximum, there is a risk of insufficient cohesion of the composition.

Advantageously, the plasticizer essentially comprises (preferably only comprises) at least one plasticizing oil. Advantageously, the content of plasticizing oil in the composition of the outer sidewall of the tire according to the invention ranges from 2phr to 60phr, preferably from 3phr to 50phr, still more preferably from 3phr to 20 phr.

II-5 various additives

The rubber composition of the outer sidewall of the tire according to the present invention may further include all or part of the usual additives commonly used in rubber compositions for tires (particularly outer sidewall compositions) known to those skilled in the art, for example, plasticizers other than the above-mentioned plasticizers (e.g., plasticizing resins), fillers other than the above-mentioned fillers, pigments, protective agents (e.g., ozone-resistant waxes, chemical antiozonants or antioxidants), or antifatigue agents.

Preparation of II-6 rubber composition

The rubber compositions according to the invention are manufactured in a suitable mixer using two successive preparation stages known to those skilled in the art:

a first stage of thermomechanical working or kneading ("non-productive" stage), which can be carried out in a single thermomechanical stage, during which all the necessary components (in particular the elastomeric matrix, the fillers and optionally other various additives) except the crosslinking system are added to a suitable mixer, for example a standard internal mixer (for example of the 'Banbury' type). The filler may be added to the elastomer by thermomechanical kneading in one portion or in batches. In the case where the filler, in particular carbon black, has been added, in whole or in part, to the elastomer in masterbatch form (for example as described in applications WO 97/36724 and WO 99/16600), the masterbatch, which is kneaded directly, the other elastomer or filler (if present) not present in the composition in masterbatch form, and optionally other various additives, are added in addition to the crosslinking system.

The non-productive phase is carried out at high temperature, with a maximum temperature of between 110 ℃ and 200 ℃, preferably between 130 ℃ and 185 ℃, for a duration generally between 2 minutes and 10 minutes.

A second stage of mechanical processing in an open mixer (e.g. open mill) (the "production" stage) after cooling the mixture obtained during the first non-production stage to a lower temperature (typically less than 120 ℃, for example between 40 ℃ and 100 ℃). The crosslinking system is then added and the combined mixture is mixed for several minutes, for example between 5 and 15 minutes.

The final composition thus obtained is then extruded, for example, in the form of a sheet or plate, in particular for laboratory characterization, or in the form of a rubber semi-finished (or profiled) element that can be used, for example, as the outer sidewall of a tyre for passenger vehicles.

The composition may be in the raw state (before crosslinking or vulcanization) or in the cured state (after crosslinking or vulcanization) and may be a semifinished product useful for tires.

Curing can be carried out under pressure at a temperature, generally between 130 ℃ and 200 ℃, for a sufficient time which can vary, in particular depending on the curing temperature, the crosslinking system employed, the crosslinking kinetics of the composition under consideration or the dimensions of the tyre, in a manner known to the person skilled in the art (for example between 5 and 90 minutes).

II-7 use of outer sidewall in tire

The above-mentioned outer sidewalls are very particularly suitable for use as finished or semi-finished products made of rubber in tyres for motor vehicles (for example, two-wheeled vehicles, passenger vehicles or industrial type vehicles).

It will be readily appreciated that the embodiments of the invention may vary depending on the particular field of application, the dimensions and pressures involved; the outer sidewall includes a number of preferred embodiments.

III examples

III-1 measurement and test of use

Measurement of ozone Performance

The ozone resistance of the material was measured according to the following method: after curing, 10 "B15" specimens were placed in an environment having an ozone content of 50pphm (parts per billion) at a temperature of 38 ℃ for 240 hours.

The "B15" sample was generated from MFTR (called monton) plates with two beads at the ends for holding the sample. The dimensions are as follows: 78.5mm 15mm 1.5 mm.

The samples were then placed on a ladder with a gradient of 10% elongation at different elongations ranging from 10% to 100%. The tensile value at break of the test specimen is taken into account. This enables the material to be classified by the maximum percent elongation. The larger the percentage, the better the ozone resistance. The samples that did not break at 100% elongation had extremely high ozone resistance.

Dynamic properties (dynamic shear modulus (G) and loss modulus (G "))

The dynamic properties G and G "were measured on a viscosity analyzer (Metravib V a4000) according to the standard ASTM D5992-96. The desired sample of the vulcanized composition (thickness 2mm, cross-section 78.5 mm) subjected to a simple alternating sinusoidal shear stress at a frequency of 10Hz at a temperature of 23 ℃ is recorded according to the standard ASTM D1349-99²Cylindrical sample of (d). Peak-to-peak strain amplitude scans were performed from 0.1% to 50% (outward cycle) and then from 50% to 1% (return cycle). The results used are complex dynamic shear modulus (G ×) and loss modulus (G "). For the return cycle, G x values at 10% strain and G "values at 10% strain are indicated.

For ease of reading, the results are shown in base 100 (percent) with the control assigned a value of 100. A result less than 100 indicates an increase in the considered value, whereas a result greater than 100 indicates a decrease in the considered value. In other words, a percentage greater than 100% means that the loss modulus G "is reduced, indicating a reduction in hysteresis and therefore an improvement in rolling resistance. Likewise, if the complex dynamic shear modulus G decreases, the percentage associated with G increases. In this case, the stiffness is improved, in particular in the outer sidewall composition for the tire.

Preparation of III-2 composition

The following tests were carried out in the following manner: the diene elastomer, the thermoplastic elastomer, the reinforcing filler and the various other ingredients, with the exception of the vulcanization system, are continuously introduced into an internal mixer (final filling degree: about 70% by volume) whose initial vessel temperature is about 60 ℃. Thermomechanical working (non-productive phase) is then carried out in one stage, for a total of about 3 to 4 minutes, until a maximum "tapping" temperature of 150 ℃ is reached.

The mixture thus obtained is recovered and cooled, then the sulphur and the vulcanization accelerator are introduced into a mixer (homogenising finisher) at 30 ℃ and all the substances are mixed (production stage) for a suitable time (for example between 5 and 12 minutes).

The compositions thus obtained were subsequently calendered in the form of rubber sheets (thickness from 1mm to 3mm) or rubber sheets, in order to measure their physical or mechanical properties.

The samples thus produced were cured in a bell compressor at 150 ℃ for 25 minutes. After cooling at room temperature for 24 hours, the samples were analyzed.

Through 360cm with CAM type blades³The Haake RM 3000 type mixer of (1) for the processing of the elastomer composition.

III-3 rubber test

The purpose of the examples shown below is to compare the ozone resistance and the hysteresis of the composition according to the invention (C1) with a control composition conventionally used for the outer sidewall of a tire (T1). Table 1 below summarizes its formulation (in phr) and its properties.

TABLE 1

(1)BR ND ML63

(2) SBIS block copolymer D1170 from Kraton

(3) Carbon Black N550 from Cabot (named according to Standard ASTM D-1765)

(4) MES oil, Catenex SNR from Shell

(5) Antioxidant, Santoflex 6PPD from Solutia

(6) Antiozonant Wax, Varazon 4959 from Sasol Wax

(7) Zinc oxide (Industrial grade-Umicore)

(8) Accelerator, Santocure CBS from Solutia

These results show that the composition according to the present invention can improve ozone resistance and rolling resistance as compared with the conventional composition for a tire. It is furthermore observed that the dynamic properties (stiffness G) of the composition according to the invention correspond to the use of the outer sidewall of the tyre.

Claims

1. Tyre provided with an outer sidewall comprising a composition based on at least one elastomeric matrix comprising:

2. Tyre according to claim 1, wherein the thermoplastic blocks of the thermoplastic elastomer are selected from the group consisting of polyolefins, polyurethanes, polyamides, polyesters, polyacetals, polyethers, polyphenylenesulfides, polyfluorinated compounds, polystyrenes, polycarbonates, polysulfones, poly (methylmethacrylates), polyetherimides, thermoplastic copolymers and mixtures of these polymers.

3. Tyre according to any one of the preceding claims, wherein the thermoplastic blocks of the thermoplastic elastomer are chosen from polystyrene, polyesters, polyamides, polyurethanes and mixtures of these polymers, preferably from polystyrene, polyesters, polyamides and mixtures of these polymers.

4. Tyre according to any one of the preceding claims, wherein the thermoplastic blocks of the thermoplastic elastomer are chosen from polystyrene.

5. Tyre according to any one of the preceding claims, wherein the elastomer blocks of the thermoplastic elastomer have a glass transition temperature of less than or equal to-50 ℃.

6. Tyre according to any one of the preceding claims, wherein the butadiene units of the elastomer block of the thermoplastic elastomer are chosen from 1, 3-butadiene units.

7. Tyre according to any one of the preceding claims, wherein the weight fraction of butadiene units of the elastomer block of the thermoplastic elastomer is in the range from 20% to 60%, preferably from 30% to 50%.

8. Tyre according to any one of the preceding claims, wherein the weight fraction of isoprene units of the elastomer block of the thermoplastic elastomer is in the range from 40% to 80%, preferably from 50% to 70%.

9. Tyre according to any one of the preceding claims, wherein the elastomeric block of the thermoplastic elastomer is a random copolymer of butadiene units and isoprene units.

10. Tyre according to any one of the preceding claims, wherein the number average molecular weight (Mn) of the elastomer blocks of the thermoplastic elastomer is in the range from 25000 to 350000g/mol, preferably from 35000 to 250000 g/mol.

11. Tire according to any one of the preceding claims, wherein the elastomer blocks of the thermoplastic elastomer are not hydrogenated.

12. Tyre according to any one of the preceding claims, wherein said thermoplastic elastomer is selected from styrene/butadiene/isoprene/styrene (SBIS) block copolymers, styrene/butadiene/isoprene (SBI) block copolymers and mixtures thereof.

13. Tyre according to any one of claims 1 to 10, wherein the elastomer blocks of the thermoplastic elastomer are partially or fully hydrogenated.

14. Tyre according to any one of the preceding claims, wherein the thermoplastic elastomer comprises two identical or different thermoplastic blocks, preferably identical, separated by at least one elastomer block.

15. Tyre according to any one of the preceding claims, wherein the content of thermoplastic elastomer in the composition is in the range from 1phr to 50phr, preferably from 5phr to 45phr, more preferably from 10phr to 40 phr.

16. Tyre according to any one of the preceding claims, wherein the diene elastomer chosen from butadiene polymers having a glass transition temperature of less than or equal to-50 ℃ is chosen from polybutadiene, butadiene copolymers, preferably butadiene/styrene copolymers, isoprene/butadiene copolymers and isoprene/butadiene/styrene copolymers, and mixtures thereof.

17. Tyre according to any one of the preceding claims, wherein the content of diene elastomer selected from butadiene polymers having a glass transition temperature of less than or equal to-50 ℃ in the composition is in the range 50phr to 99phr, preferably 55phr to 95phr, more preferably 60phr to 90 phr.

18. Tyre according to any one of the preceding claims, wherein said crosslinking system is based on molecular sulphur and/or a sulphur-donating agent.

19. Tyre according to claim 18, wherein the composition has a content of sulphur or sulphur donor comprised between 0.5phr and 2phr, preferably between 0.5phr and 1.5phr, more preferably between 0.5phr and 1.4 phr.

20. Tyre according to any one of the preceding claims, wherein said reinforcing filler comprises carbon black and/or silica.

21. Tyre according to any one of the preceding claims, wherein said reinforcing filler mainly comprises carbon black.

22. Tyre according to claim 20 or 21, wherein the carbon black has a BET specific surface of less than 70m²A/g, preferably less than 50m²/g。

23. Tyre according to any one of the preceding claims, wherein the content of reinforcing filler in the composition is in the range from 5phr to 70phr, preferably from 5phr to 55 phr.