Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
  • B60C1/0016—Compositions of the tread
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
  • B60C11/0008—Tyre tread bands; Tread patterns; Anti-skid inserts characterised by the tread rubber
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
  • B60C11/0041—Tyre tread bands; Tread patterns; Anti-skid inserts comprising different tread rubber layers
  • B60C11/005—Tyre tread bands; Tread patterns; Anti-skid inserts comprising different tread rubber layers with cap and base layers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F210/00—Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
  • C08F210/02—Ethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/34—Silicon-containing compounds
  • C08K3/36—Silica
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/04—Homopolymers or copolymers of ethene
  • C08L23/08—Copolymers of ethene
  • C08L23/0807—Copolymers of ethene with unsaturated hydrocarbons only containing four or more carbon atoms
  • C08L23/083—Copolymers of ethene with unsaturated hydrocarbons only containing four or more carbon atoms with aliphatic polyenes, i.e. containing two or more carbon-to-carbon double bonds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
  • B60C11/0008—Tyre tread bands; Tread patterns; Anti-skid inserts characterised by the tread rubber
  • B60C2011/0016—Physical properties or dimensions
  • B60C2011/0025—Modulus or tan delta
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F4/00—Polymerisation catalysts
  • C08F4/42—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors
  • C08F4/44—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors selected from light metals, zinc, cadmium, mercury, copper, silver, gold, boron, gallium, indium, thallium, rare earths or actinides
  • C08F4/54—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors selected from light metals, zinc, cadmium, mercury, copper, silver, gold, boron, gallium, indium, thallium, rare earths or actinides together with other compounds thereof
  • C08F4/545—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors selected from light metals, zinc, cadmium, mercury, copper, silver, gold, boron, gallium, indium, thallium, rare earths or actinides together with other compounds thereof rare earths being present, e.g. triethylaluminium + neodymium octanoate
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F4/00—Polymerisation catalysts
  • C08F4/42—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors
  • C08F4/44—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors selected from light metals, zinc, cadmium, mercury, copper, silver, gold, boron, gallium, indium, thallium, rare earths or actinides
  • C08F4/60—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors selected from light metals, zinc, cadmium, mercury, copper, silver, gold, boron, gallium, indium, thallium, rare earths or actinides together with refractory metals, iron group metals, platinum group metals, manganese, rhenium technetium or compounds thereof
  • C08F4/619—Component covered by group C08F4/60 containing a transition metal-carbon bond
  • C08F4/6192—Component covered by group C08F4/60 containing a transition metal-carbon bond containing at least one cyclopentadienyl ring, condensed or not, e.g. an indenyl or a fluorenyl ring
  • C08F4/61922—Component covered by group C08F4/60 containing a transition metal-carbon bond containing at least one cyclopentadienyl ring, condensed or not, e.g. an indenyl or a fluorenyl ring containing at least two cyclopentadienyl rings, fused or not
  • C08F4/61927—Component covered by group C08F4/60 containing a transition metal-carbon bond containing at least one cyclopentadienyl ring, condensed or not, e.g. an indenyl or a fluorenyl ring containing at least two cyclopentadienyl rings, fused or not two cyclopentadienyl rings being mutually bridged
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L91/00—Compositions of oils, fats or waxes; Compositions of derivatives thereof
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/80—Technologies aiming to reduce greenhouse gasses emissions common to all road transportation technologies
  • Y02T10/86—Optimisation of rolling resistance, e.g. weight reduction 

Definitions

• the present invention relates to a tire for vehicles, and, in particular, the tread of a tire for a vehicle.
• a tire having a geometry of revolution relative to an axis of rotation the geometry of the tire is generally described in a meridian plane containing the axis of rotation of the tire.
• the radial, axial and circumferential directions respectively designate the directions perpendicular to the axis of rotation of the tire, parallel to the axis of rotation of the tire and perpendicular to the meridian plane.
• the expressions "radially”, “axially” and “circumferentially” mean respectively "in the radial direction”, “in the axial direction” and "in the circumferential direction”.
• radially inner, respectively radially outer is meant “closer, respectively farther from the axis of rotation of the tire”.
• axially interior, respectively axially exterior is meant “closer, respectively farther from the equatorial plane of the tire”, the equatorial plane of the tire being the plane passing through the middle of the tire rolling surface and perpendicular to the axis of rotation of the tire.
• the tread is the part of the tire intended to come into contact with the ground via a tread surface and extending radially from a bottom surface to the tread surface, axially from a first edge to a second tread edge defining the axial width of the tread, and circumferentially over the entire periphery of the tire.
• the tread whether the tire is intended to equip a passenger vehicle or a heavy vehicle, is provided with a tread pattern comprising in particular tread elements or elementary blocks delimited by various main grooves, longitudinal or circumferential, transverse or else oblique, the elementary blocks being able moreover to comprise various incisions or finer lamellae.
• the grooves constitute channels intended to evacuate the water during rolling on wet ground.
• a radial type tire comprises a reinforcing reinforcement, consisting of a crown reinforcement and a radial carcass reinforcement radially internal to the crown reinforcement.
• the crown reinforcement comprises at least one crown layer constituted by reinforcing elements or reinforcements coated with a rubber mixture and parallel to each other.
• the radial carcass reinforcement comprises at least one carcass layer constituted by reinforcements coated with a rubber mixture, mutually parallel and oriented substantially radially, that is to say forming, with the circumferential direction, an angle between 85 ° and 95 °.
• the rubber compositions of the treads of the tires are specialized for contact performance with a road surface, and this until the regulatory wear of the tires.
• the tread of a tire is responsible for a large part of the rolling resistance of this tire. This contribution is of course very variable depending on the design of the tire, but an order of magnitude of the order of 50% can be achieved.
• the document EP0869016 A2 presents such a tread with a first radially inner layer and a second radially outer layer, such that during wear of the tread the first radially inner layer comes progressively more and more into contact with the rolling floor.
• the rubber composition of the first layer has a higher adhesion performance than that of the second layer.
• the performance compromise between the rolling resistance and the wear resistance of the treads has been improved by the introduction into a rubber composition of a copolymer of ethylene and of 1, 3- butadiene containing more than 50% by mole of ethylene unit.
• a rubber composition of a copolymer of ethylene and of 1, 3- butadiene containing more than 50% by mole of ethylene unit.
• such a composition does not allow the tread to be given optimum grip performance, in particular for a passenger vehicle.
• this stiffening of the tread can be obtained for example by increasing the rate of reinforcing filler or by incorporating certain reinforcing resins in the rubber compositions making up these treads. But generally, these solutions are not always satisfactory, because they can be accompanied by a deterioration in rolling resistance.
• one solution also consists in creating a stiffness gradient by a phenomenon of accommodation of the rubber composition of the tread as described.
• This accommodation phenomenon results in the ability of the rubber composition to become less rigid on the surface of the tread under the effect of the deformations undergone by the tread during the rolling of the tire. This reduction in rigidity at the surface of the tread, does not occur or very little inside the tread which thus retains a higher level of rigidity than the surface of the tread.
• the Applicant has discovered that the combined use of a highly saturated diene elastomer and a specific plasticizer system in a rubber composition for the tread of a tire makes it possible to improve the performance of tire grip.
• Embodiments individuals of the invention even contribute to improving the performance compromise between grip and rolling resistance.
• Other particular embodiments of the invention also make it possible to improve the performance compromise between grip and road behavior.
• An object of the invention is a tire having an axis of rotation and comprising a crown extended by two sidewalls and two beads, a carcass reinforcement anchored in the two beads, a crown reinforcement and a radially rubbery tread external to said crown reinforcement, the tread comprising a radially internal first layer C1 and a radially external second layer C2, the first and second layers being intended to be in contact with a rolling ground in new condition or in 'worn condition.
• This tire is characterized in that the rubber composition of the first layer C1 comprises more than 50 phr of an ethylene copolymer and a 1, 3-diene, a reinforcing filler and a plasticizing system, 1, 3- diene being 1, 3-butadiene or isoprene and the ethylene units in the copolymer representing more than 50 mol% of all the monomer units of the copolymer.
• a mass content or content of the copolymer of ethylene and a 1,3-diene of the layer C1 greater than 50 phr means that this copolymer of ethylene and a 1,3-diene is the majority elastomer in the rubber composition of the first layer C1 of the tread.
• This majority rate of copolymer of ethylene and a 1,3-diene contributes to obtaining good road behavior of the tire. It can also participate in improving the tire rolling resistance performance.
• the rubber composition of the layer C1 comprises a second elastomer, preferably diene, that is to say comprising diene monomer units.
• the level of the second elastomer is preferably less than 30 phr and very preferably less than 10 phr.
• the second elastomer can be a highly unsaturated diene elastomer chosen from the group consisting of polybutadienes, polyisoprenes, butadiene copolymers, isoprene copolymers and mixtures of these elastomers.
• the copolymer of ethylene and a 1,3-diene is the only elastomer of the rubber composition of the first layer C1.
• the composition rubbery of the second layer C2 comprises less than 50 phr of an ethylene copolymer and a 1,3-diene.
• the ratio K between the dynamic shear modulus of the rubber composition of the first layer C1 and the dynamic shear modulus of the rubber composition of the second layer C2 is greater than 1.1 and preferably greater than 1 , 2, the dynamic shear moduli being measured at 60 ° C. during a temperature sweep at an imposed stress of 0.7 MPa and at a frequency of 10 Hz.
• This ratio of modules between the two layers C1 and C2 of the tread allows the layer C1 to stiffen the tread and the top of the tire. This improves the road behavior of the tire.
• K less than 2.5 and preferably less than or equal to 1.5.
• the dynamic shear modulus of the rubber composition of the first layer C1 is between 1 and 2.5 MPa, the dynamic shear modulus being measured at 60 ° C. during a temperature sweep at a stress. 0.7 MPa and at a frequency of 10 Hz.
• the grip performance of the tire can be reduced when the layer C1 comes into contact with the road surface.
• the tread comprising ribs separated by grooves with a bottom, the limit of use of the tire being defined by a minimum radial height h of these ribs relative to the bottoms of those here, VC1 and VC2 being the volumes of materials C1 and C2 located in the tread at a radial height greater than said minimum radial height h, the ratio VC1 / VC2 is greater than 15%, preferably greater than 25% and even more preferably greater than 35%.
• the VC1 / VC2 ratio is less than 75%.
• FIG. 1 represents a partial axial half-section of a tire.
• Figure 1 shows a partial sectional view in a meridian plane of the top of a tire 1 according to the invention.
• This tire 1 notably comprises radially from the inside to the outside a carcass reinforcement 2, a crown reinforcement 3 and a tread 4 which is extended laterally by a sidewall 5.
• the tread 4 comprises a first layer C1 and a second layer C2.
• the tread 4 also has circumferential grooves 6.
• the radially outer surface of the layer C2 constitutes the tread surface of the tire on a road surface.
• the layer C1 comes into contact with the road surface.
• FIG. 1 also shows the median plane EP and the axis of rotation YY ’.
• the circumferential grooves 6 include bosses or wear indicators intended to illustrate the maximum wear acceptable by law of the tread.
• the axially outer circumferential groove 6 shows such a boss 61.
• the minimum regulatory height is 1.6 mm and the wear indicators usually have a slightly higher height h. This height is measured from the bottoms 62 of the circumferential grooves 6.
• Line L corresponds to the intersection between the toric surface S of general shape of the running surface of the tread and offset radially outwardly relative to the bottoms of the circumferential grooves of a height h.
• the volume V of the tread corresponds to the “usable” volume of the latter. This volume is equal to the sum of the volumes VC1 of the layer C1 and VC2 of the layer C2 arranged radially externally relative to the surface S.
• the intersections of these volumes with the meridian plane of FIG. 1 correspond to the surfaces SC1 and SC2.
• the surfaces SC1 are slightly grayed out to distinguish them in the layer C1
• the surfaces SC2 are also represented with a texture of points to distinguish them in the layer C2.
• FIG. 1 illustrates well the role of stiffening of the tread and of the top of the tire when the dynamic modulus ratio between the two rubber mixtures of the layers C1 and C2 is greater than 1, 1 and preferably greater than 1, 2. It is preferable not to exceed a ratio of 2.5, and very preferably 1.5, in order not to degrade the grip of the tire when the rolling surface is largely due to the C1 layer.
• any range of values designated by the expression “between a and b” represents the range of values greater than “a” and less than “b” (that is to say bounds a and b excluded) while any range of values designated by the expression “from a to b” means the range of values going from “a” to "b” (that is to say including the strict limits a and b).
• the abbreviation “pce” means parts by weight per hundred parts by weight of elastomer (of the total of the elastomers if several elastomers are present).
• the term "all of the monomer units of the elastomer" or “all of the monomer units of the elastomer” means all of the repeating units constituting the elastomer which result from the insertion of the monomers into the elastomer chain by polymerization. Unless otherwise indicated, the contents of a monomer unit or repeating unit in the highly saturated diene elastomer are given in molar percentage calculated on the basis of the monomer units of the copolymer, that is to say of all the monomer units of the elastomer.
• the compounds mentioned in the description can be of fossil origin or bio-based. In the latter case, they can be, partially or totally, from biomass or obtained from renewable raw materials from biomass. Are concerned in particular elastomers, plasticizers, fillers ...
• the copolymer of ethylene and of 1,3-diene useful for the needs of the invention is an elastomer preferably statistical, which comprises ethylene units resulting from the polymerization of ethylene.
• ethylene unit refers to the motif - (CH2-CH2) - resulting from the insertion of ethylene into the elastomer chain.
• the ethylene units represent more than 50 mol% of the monomer units of the copolymer.
• the ethylene units in the copolymer represent more than 60%, advantageously more than 70% by mole of the monomer units of the copolymer.
• the highly saturated diene elastomer preferably comprises at most 90 mol% of ethylene unit.
• the copolymer useful for the needs of the invention also designated below under the name of “highly saturated diene elastomer”, also comprises 1, 3-diene units resulting from the polymerization of a 1, 3 -diene, 1, 3-diene being 1, 3-butadiene or isoprene.
• 1, 3-diene unit refers to the units resulting from the insertion of 1, 3-diene by an addition 1, 4, an addition 1, 2 or an addition 3,4 in isoprene case.
• the 1,3-diene is 1,3-butadiene.
• the ethylene copolymer and of a 1,3-diene contains units of formula (I).
• the presence of a 6-membered 1,2-cyclohexanediyl saturated cyclic unit of formula (I) as the monomer unit in the copolymer may result from a series of very specific insertions of ethylene and of 1, 3-butadiene in the polymer chain during its growth.
• the copolymer of ethylene and a 1,3-diene contains units of formula (11-1) or (I I-2).
• the copolymer of ethylene and a 1,3-diene contains units of formula (I) and of formula (11-1).
• the highly saturated diene elastomer is devoid of units of formula (I).
• the copolymer of ethylene and a 1,3-diene preferably contains units of formula (11-1) or (I i-2).
• the highly saturated diene elastomer comprises units of formula (I) or units of formula (11-1) or also comprises units of formula (I) and units of formula (11-1)
• the molar percentages of the units of formula (I) and of the units of formula (11-1) in the highly saturated diene elastomer, respectively o and p preferably satisfy the following equation (eq. 1), more preferably in equation (eq. 2), o and p being calculated on the basis of all the monomer units of the highly saturated diene elastomer.
• the highly saturated diene elastomer is preferably a random copolymer.
• the highly saturated diene elastomer in particular according to the first embodiment, according to the second embodiment, according to the third embodiment and according to the fourth embodiment, can be obtained according to various known synthetic methods of those skilled in the art, in particular depending on the targeted microstructure of the highly saturated diene elastomer. Generally, it can be prepared by copolymerization of at least one 1,3-diene, preferably 1,3-butadiene, and ethylene and according to known synthesis methods, in particular in the presence of a catalytic system comprising a metallocene complex.
• the highly saturated diene elastomer can also be prepared by a process using a catalytic system of the preformed type such as those described in documents WO 2017093654 A1, WO 2018020122 A1 and WO 2018020123 A1.
• the highly saturated diene elastomer may consist of a mixture of copolymers of ethylene and of 1,3-diene which differ from one another by their microstructures or by their macrostructures.
• the highly saturated diene elastomer is preferably a copolymer ethylene and 1,3-butadiene, more preferably a copolymer of ethylene and 1,3-butadiene random.
• the copolymer of ethylene and a 1,3-diene carries at the chain end a functional group F1 which is a silanol or alkoxysilane function.
• This embodiment is also favorable to improving the rolling resistance.
• the silanol or alkoxysilane function is located at the end of the chain of the highly saturated diene elastomer.
• the alkoxysilane or silanol function carried at one of the ends is designated in the present application by the designation functional group F1.
• it is attached directly by a covalent bond to the terminal unit of the highly saturated diene elastomer, which amounts to saying that the silicon atom of the function is directly linked covalently to a carbon atom of the terminal unit of the highly saturated diene elastomer.
• the terminal unit to which the functional group F1 is directly attached preferably consists of a methylene linked to an ethylene unit or to a 1,2-cyclohexanediyl unit, of formula (I), the Si atom being linked to methylene .
• terminal unit is meant the last unit inserted in the copolymer chain by copolymerization, unit which is preceded by the penultimate unit, itself preceded by the ante-penultimate unit.
• the functional group F1 is of formula (III-A)
• R 2 identical or different, representing a hydrogen atom, a hydrocarbon chain or a hydrocarbon chain substituted by a chemical function F 2 ,
• R 1 are preferably an alkyl having at most 6 carbon atoms, more preferably a methyl or an ethyl, even more preferably a methyl.
• R 1 are advantageously identical, in particular methyl or ethyl, more particularly methyl.
• the functional group F 1 has the formula (Ill-b)
• R 2 identical or different, representing a hydrogen atom, a hydrocarbon chain or a hydrocarbon chain substituted by a chemical function F 2 .
• alkyls in particular those having 1 to 6 carbon atoms, preferably methyl or ethyl, more preferably methyl.
• alkanediyl chains in particular those containing at most 6 carbon atoms, most particularly the 1,3-propanediyl group, the alkanediyl group carrying a substituent, the chemical function F2, in other words, one valence of the alkanediyl chain for the function F2, the other valence for the silicon atom of the silanol function or alkoxysilane.
• the term chemical function F2 is understood to mean a group which is different from a saturated hydrocarbon group and which can participate in chemical reactions.
• the chemical functions which may be suitable mention may be made of the ether function, the thioether function, the primary, secondary or tertiary amine function, the thiol function and the silyl function.
• the primary or secondary amine or thiol functions may or may not be protected.
• the protecting group for the amine and thiol functions is for example a silyl group, in particular trimethylsilyl or terbutyldimethylsilyl.
• the chemical function F2 is a primary, secondary, tertiary amine function or a thiol function, the primary, secondary or thiol amine function being protected or not by a protective group.
• the symbols R2 which are identical or different, represent an alkyl having at most 6 carbon atoms or an alkanediyl chain having at most 6 carbon atoms and substituted by a chemical function F2 in the formulas (III-A) and (III-b).
• the dimethylsilanol, diethylsilanol, 3- (N, N-dimethylamino) propylmethylsilanol, 3- (N, N-dimethylamino) propyl-ethylsilanol, 3-aminopropylmethylsilanol, 3-aminopropylethylsilanol, 3-thiopropylethylsilanol groups are suitable. thiopropylmethylsilanol.
• functional group F1 there may also be mentioned the functional groups, whether they are in the alkoxy or silanol form, which have been mentioned previously and which comprise an amine or thiol function in a form protected by a silyl group, in particular trimethylsilyl or terbutyldimethylsilyl.
• the functional group F1 is of formula (III-A) in which f is equal to 1.
• the groups for which R1 is methyl or ethyl are particularly suitable, such as for example the dimethoxymethylsilyl, dimethoxyethylsilyl, diethoxymethysilyl, diethoxyethysilyl, 3- (N, N-dimethylamino) propyldimethoxysilyl, 3- (N, N-dimethylamino) propyldiethoxysilyl, 3-aminopropyldimethoxysilyl, 3-aminopropyl-diethoxysilyl, 3-thiopropyldimethoxysilyl, 3-thiopropyldiethoxysilyl.
• Protected forms of the amine or thiol function of the last 4 functional groups mentioned in the preceding list are also suitable for a silyl group, in particular trimethylsilyl or terbutyldi
• the functional group F1 is of formula (III-a) in which f is 1 and R1 is methyl.
• the dimethoxymethylsilyl, dimethoxyethylsilyl, 3- (N, N-dimethylamino) propyldimethoxysilyl, 3-aminopropyldimethoxysilyl, 3-thiopropyldimethoxysilyl, as well as protected forms of the amine or thiol or 3-aminopropyl function are particularly suitable.
• the copolymer of ethylene and a 1,3-diene which carries at the chain end a functional group F1, silanol or alkoxysilane function can be prepared by the process described in the patent application filed under the number PCT / FR2018 / 051305 or in the patent application filed under the number PCT / FR2018 / 051306, which method comprises steps (a) and (b), and where appropriate step (c) following:
• step (b) the reaction of a functionalizing agent with the polymer obtained in step (a);
• Step (a) is common to the copolymerization step used to prepare the non-functional homologous copolymers described above, with the difference that the copolymerization reaction is followed by a functionalization reaction of the copolymer, l 'step (b).
• Step (b) consists in reacting a functionalizing agent with the copolymer obtained in step (a) to functionalize the copolymer at the chain end.
• the functionalizing agent is a compound of formula (IV),
• - g being an integer ranging from 0 to 2.
• the alkoxy group is preferably methoxy or ethoxy.
• the symbol Fc1 represents a halogen atom
• the halogen atom is preferably chlorine.
• the functionalizing agent can be of formula (IV-1), of formula (IV-2), of formula (IV-3) or of formula (IV-4),
• g being an integer ranging from 0 to 1.
• alkyls of preferably alkyls having at most 6 carbon atoms, more preferably methyl or ethyl, better methyl.
• the alkanediyl chains preferably those containing at most 6 carbon atoms, more preferably the group 1, 3-propanediyl, the alkanediyl group carrying a substituent, the chemical function Fc2, in other words a valence of the chain alkanediyl for the F2 function, the other valence for the silicon atom of the silanol or alkoxysilane function.
• the term “chemical function” means a group which is different from a saturated hydrocarbon group and who can participate in chemical reactions.
• the chemical function Fc2 is a group chemically inert with respect to the chemical species present in the polymerization medium.
• the chemical function Fc2 can be in a protected form, as for example in the case of the primary amine, secondary amine or thiol function.
• the chemical function Fc2 is a protected primary amine function, a protected secondary amine function, a tertiary amine function or a protected thiol function.
• protecting groups for the primary amine, secondary amine and thiol functions mention may be made of silyl groups, for example the trimethylsilyl and terbutyldimethylsilyl groups.
• g is preferably different from 0, which implies that the functionalizing agent comprises at least one Si-Rc2 bond.
• dimethoxydimethylsilane diethoxydimethylsilane, dimethoxydiethylsilane, diethoxydiethylsilane, (N, N-dimethyl-3-aminopropyl) methyldimethoxysilane, (N, N-dimethyl-3-aminopropyl) methylane compounds.
• the functionalizing agent is typically added to the polymerization medium resulting from step (a). It is typically added to the polymerization medium at a rate of conversion of the monomers chosen by a person skilled in the art according to the desired macrostructure of the elastomer. Since step (a) is generally carried out under ethylene pressure, degassing of the polymerization reactor can be carried out before the addition of the functionalizing agent.
• the functionalizing agent is added under inert and anhydrous conditions to the polymerization medium, maintained at the polymerization temperature. Typically, 0.25 to 10 moles of functionalizing agent are used per 1 mole of co-catalyst, preferably 2 to 4 moles of functionalizing agent per 1 mole of co-catalyst.
• the functionalizing agent is brought into contact with the polymerization medium for a time sufficient to allow the functionalization reaction.
• This contact time is judiciously chosen by a person skilled in the art as a function of the concentration of the reaction medium and the temperature of the reaction medium.
• the functionalization reaction is carried out with stirring, at a temperature ranging from 17 to 80 ° C, for 0.01 to 24 hours.
• the elastomer can be recovered, in particular by isolating it from the reaction medium.
• the techniques for separating the elastomer from the reaction medium are well known to a person skilled in the art and chosen by a person skilled in the art according to the quantity of elastomer to be separated, its macrostructure and the tools made available to a person skilled in the art. . Mention may be made, for example, of the techniques for coagulating the elastomer in a solvent such as methanol, the techniques for evaporating the solvent from the reaction medium and the residual monomers, for example under reduced pressure.
• step (b) can be followed by a hydrolysis reaction to form an elastomer carrying a silanol function at the end of the chain.
• the hydrolysis can be carried out by a step of stripping the solution containing the elastomer at the end of step (b), in a manner known to a person skilled in the art.
• step (b) can also be followed by a hydrolysis reaction to deprotect the function at the end of the elastomer chain.
• the hydrolysis reaction, the deprotection step of the function is generally carried out in an acidic or basic medium depending on the chemical nature of the function to be deprotected.
• a silyl group in particular trimethylsilyl or terbutyldimethylsilyl, which protects an amine or thiol function can be hydrolyzed in an acidic or basic medium in a manner known to a person skilled in the art.
• the choice of deprotection conditions is made judiciously by a person skilled in the art, taking into account the chemical structure of the substrate to be deprotected.
• Step (c) is an optional step depending on whether or not one wishes to transform the functional group into a silanol function or whether one wishes to unprotect or not the protected function.
• step (c) is carried out before separating the elastomer from the reaction medium at the end of step (b) or else simultaneously with this separation step.
• the level of the copolymer of ethylene and of a 1,3-diene is greater than 50 phr, preferably greater than 70 phr.
• the complement to 100 phr can be any diene elastomer, for example a homopolymer or a copolymer of 1, 3-butadiene or also a homopolymer or a copolymer of isoprene.
• the content of the copolymer of ethylene and of a 1,3-diene is 100 phr.
• a high content of the copolymer in the rubber composition is even more favorable for the performance compromise between rolling resistance, wear resistance and adhesion.
• Another essential characteristic of the rubber composition of layer C1 is to include a reinforcing filler and a plasticizing system.
• the plasticizer system is preferably hydrocarbon.
• the reinforcing filler comprises a silica.
• a reinforcing filler typically consists of nanoparticles whose average size (by mass) is less than a micrometer, generally less than 500 nm, most often between 20 and 200 nm, in particular and more preferably between 20 and 150 nm.
• the level of reinforcing filler in the rubber composition of the layer C1 is advantageously greater than or equal to 35 phr and less than or equal to 100 phr, preferably greater than or equal to 50 phr and less than or equal to 100 phr.
• the silica represents more than 50% by mass of the reinforcing filler. More preferably, the silica represents more than 85% by mass of the reinforcing filler.
• the reinforcing filler of the rubber composition of layer C1 comprises from 35 to 100 phr of a reinforcing filler which comprises silica.
• the silica used can be any reinforcing silica known to those skilled in the art, in particular any precipitated or pyrogenic silica having a BET specific surface as well as a CTAB specific surface, both of which are less than 450 m2 / g, preferably included in an area ranging from 30 to 400 m2 / g, in particular from 60 to 300 m2 / g.
• the BET surface area is determined by gas adsorption using the Brunauer-Emmett-Teller method described in "The Journal of the American Chemical Society” (Vol.
• CTAB specific surface values were determined according to standard NF ISO 5794-1, annex G of June 2010. The process is based on the adsorption of CTAB (bromide of N-hexadecyl-N, N, N- trimethylammonium) on the "external" surface of the reinforcing filler.
• any type of precipitated silica can be used, in particular highly dispersible precipitated silicas (called “HDS” for “highly dispersible” or “highly dispersible silica ").
• HDS highly dispersible precipitated silicas
• These precipitated silicas, highly dispersible or not, are well known to those skilled in the art. Mention may be made, for example, of the silicas described in applications W003 / 016215-A1 and W003 / 016387-A1.
• Non-HDS silica the following commercial silicas can be used: “Ultrasil® VN2GR”, “Ultrasil® VN3GR” from Evonik, “Zeosil® 175GR” from Silvay, “Hi” -Sil EZ120G (-D) “,” Hi-Sil EZ160G (-D) “,” Hi-Sil EZ200G (-D) “,” Hi-Sil 243LD “,” Hi-Sil 210 ",” Hi-Sil HDP 320G ”from PPG
• the reinforcing filler can comprise any type of so-called reinforcing filler other than silica, known for its capacity to reinforce a rubber composition which can be used in particular for the manufacture of tires, for example a carbon black.
• carbon blacks all carbon blacks are suitable, in particular the blacks conventionally used in tires or their treads.
• the reinforcing carbon blacks of the 100, 200, 300 series, or the blacks of the 500, 600 or 700 series grades ASTM D-1765-2017), such as, for example, the blacks N115, N134, N234, N326, N330, N339, N347, N375, N550, N683, N772).
• These carbon blacks can be used in the isolated state, as commercially available, or in any other form, for example as a support for some of the rubber additives used.
• the carbon black is used at a rate less than or equal to 20 phr, more preferably less than or equal to 10 phr (for example the level of carbon black can be included in a range ranging from 0.5 at 20 pc, in particular ranging from 1 to 10 pc).
• the level of carbon black in the rubber composition is less than or equal to 5 phr. In the indicated intervals, the coloring properties (black pigmentation agent) and anti-UV properties of the carbon blacks are benefited, without, moreover, penalizing the typical performances provided by silica.
• a coupling agent or bonding agent
• the rubber composition of the layer C1 comprises a coupling agent for binding the silica to the elastomer.
• organosilanes or polyorganosiloxanes which are at least bifunctional are used.
• bifunctional a compound having a first functional group capable of interacting with the inorganic charge and a second functional group capable of interacting with the elastomer is understood.
• polysulphurized silanes known as “symmetrical” or “asymmetrical” depending on their particular structure, are used, as described for example in applications W003 / 002648-A1 (or US2005 / 016651-A1) and W003 / 002649-A1 (or US2005 / 016650-A1).
• polysulphurized silanes corresponding to the following general formula (V):
• - x is an integer from 2 to 8 (preferably from 2 to 5);
• the symbols A which are identical or different, represent a divalent hydrocarbon radical (preferably a C1-C18 alkylene group or a C6-C12 arylene group, more particularly a C1-C10 alkylene, in particular a C1-C4 alkylene , in particular propylene);
• the radicals Ra substituted or unsubstituted, identical or different from each other, represent a C1-C18 alkyl group, a C5-C18 cycloalkyl group or a C6-C18 aryl group (preferably C1-C6 alkyl groups , cyclohexyl or phenyl, in particular C1-C4 alkyl groups, more particularly methyl and / or ethyl);
• radicals Rb substituted or unsubstituted, identical or different from each other, represent a C1-C18 alkoxyl group or a C5-C18 cycloalkoxyl group (preferably a group chosen from C1-C8 alkoxyls and C5 cycloalkoxyls -C8, more preferably still a group chosen from C1-C4 alkoxyls, in particular methoxyl and ethoxyl), or a hydroxyl group, or such that 2 radicals Rb represent a C3-C18 dialkoxyl group.
• the average value of "x" is a fractional number preferably within a range ranging from 2 to 5, more preferably close to 4.
• polysulphide silanes By way of examples of polysulphide silanes, mention will be made more particularly of the polysulphides (in particular disulphides, trisulphides or tetrasulphides) of bis- (alkoxyl (C1 -C4) - alkyl (C1 -C4) silyl-alkyl (C1 -C4) )), such as for example the bis (3-trimethoxysilylpropyl) or bis (3-triethoxysilylpropyl) polysulphides.
• polysulphides in particular disulphides, trisulphides or tetrasulphides
• TESPT bis (3-triethoxysilylpropyl) tetrasulfide
• TESPD bis (3-triethoxysilylpropyl) tetrasulfide
• polysulphides in particular disulphides, trisulphides or tetrasulphides
• polysulphides of bis- (monoalkoxyl (Ci-C 4 ) -dialkyl (Cr C 4 ) silylpropyl), more particularly bis-monoethoxydimethylsilylpropyl tetrasulphide such as described in patent application WO02 / 083782-A1 cited above (or US7217751 -B2).
• the content of coupling agent in the rubber composition of the layer C1 is advantageously less than or equal to 25 phr, it being understood that it is generally desirable to use as little as possible.
• the level of coupling agent represents from 0.5% to 15% by weight relative to the amount of reinforcing inorganic filler. Its rate is preferably included in a range ranging from 0.5 to 20 phr, more preferably included in a range ranging from 3 to 15 phr. This rate is easily adjusted by a person skilled in the art according to the rate of reinforcing inorganic filler used in the composition of layer C1 of the tread of the tire of the invention.
• Another essential characteristic of the rubber composition of the layer C1 is to include a plasticizer system.
• This plasticizing system advantageously comprises a hydrocarbon plasticizing resin and a liquid hydrocarbon plasticizing agent, it being understood that the total level of hydrocarbon plasticizing resin and liquid hydrocarbon plasticizing agent is greater than 10 phr and less than or equal to 80 phr, preferably greater than or less equal to 30 pce and less than or equal to 80 pce.
• Hydrocarbon resins also called plasticizing hydrocarbon resins
• plasticizing hydrocarbon resins are polymers well known to those skilled in the art, essentially based on carbon and hydrogen but which may contain other types of atoms, for example oxygen, which can be used in particular as plasticizers or tackifiers in polymeric matrices. They are by nature at least partially miscible (ie, compatible) at the levels used with the polymer compositions for which they are intended, so as to act as true diluents. They have been described for example in the work entitled "Hydrocarbon Resins” by R. Mildenberg, M. Zander and G. Collin (New York, VCH, 1997, ISBN 3-527-28617-9), chapter 5 of which is devoted to their applications, especially in pneumatic rubber (5.5.
• thermoplastic resins in the sense that they soften by heating and can thus be molded.
• the softening point of hydrocarbon resins is measured according to ISO standard 4625 ("Ring and Bail” method).
• the Tg is measured according to standard ASTM D3418 (1999).
• the macrostructure (Mw, Mn and Ip) of the hydrocarbon resin is determined by steric exclusion chromatography (SEC): tetrahydrofuran solvent; temperature 35 ° C; concentration 1 g / l; flow 1 ml / min; solution filtered on a 0.45 ⁇ m porosity filter before injection; Moore calibration with polystyrene standards; set of 3 "WATERS” columns in series (“STYRAGEL” HR4E, HR1 and H R0.5); detection by differential refractometer (“WATERS 2410") and its associated operating software (“WATERS EMPOWER").
• SEC steric exclusion chromatography
• the hydrocarbon resins can be aliphatic, or aromatic or else of the aliphatic / aromatic type, that is to say based on aliphatic and / or aromatic monomers. They can be natural or synthetic, based on petroleum or not (if this is the case, also known as petroleum resins).
• the plasticizing hydrocarbon resin has a glass transition temperature above 20 ° C.
• the plasticizing hydrocarbon resin has at least any one of the following characteristics, more preferably all:
• Mn number average molecular mass
• the plasticizing hydrocarbon resin is chosen from the group consisting of cyclopentadiene homopolymer resins, cyclopentadiene copolymer resins, dicyclopentadiene homopolymer resins, dicyclopentadiene copolymer resins, dicyclopentadiene copolymer resins homopolymer of terpene, terpene copolymer resins, C5 cut homopolymer resins, C5 cut copolymer, C9 cut homopolymer resins, C9 cut copolymer resins, hydrogenated cyclopentadiene homopolymer resins and hydrogenated cyclopentadiene copolymer resins.
• the plasticizing hydrocarbon resin is a C9 cut copolymer resin or a dicyclopentadiene copolymer resin, hydrogenated or not.
• the plasticizing hydrocarbon resin is a C9 cut copolymer resin or a dicyclopentadiene copolymer resin, hydrogenated or not.
• Hydrocarbon liquid plasticizers are known to soften a rubber composition by diluting the elastomer and the reinforcing filler of the rubber composition.
• Their Tg is typically less than -20 ° C, preferably less than -40 ° C.
• Any hydrocarbon extension oil or any liquid hydrocarbon plasticizing agent known for its plasticizing properties with respect to diene elastomers can be used.
• these more or less viscous plasticizers or oils are liquids (that is to say, substances having the capacity to take the form of their container in the long term) , as opposed in particular to plasticizing hydrocarbon resins which are by nature solid at room temperature.
• liquid plasticizing hydrocarbon agents mention may be made of liquid diene polymers, polyolefin oils, naphthenic oils, paraffinic oils, DAE oils, MES oils (Medium Extracted Solvates), TDAE oils (Treated Distillate Aromatic Extracts) ), RAE oils (Residual Aromatic Extract oils), TRAE oils (Treated Residual Aromatic Extract) and SRAE oils (Safety Residual Aromatic Extract oils), mineral oils, and mixtures of these compounds.
• liquid diene polymers polyolefin oils, naphthenic oils, paraffinic oils, DAE oils, MES oils (Medium Extracted Solvates), TDAE oils (Treated Distillate Aromatic Extracts) ), RAE oils (Residual Aromatic Extract oils), TRAE oils (Treated Residual Aromatic Extract) and SRAE oils (Safety Residual Aromatic Extract oils), mineral oils, and mixtures of these compounds.
• the liquid hydrocarbon plasticizer is chosen from the group consisting of liquid diene polymers, aliphatic polyolefin oils, paraffinic oils, MES oils, TDAE oils, TRAE oils, SRAE oils, mineral oils and their mixtures. More preferably, the liquid hydrocarbon plasticizer is a liquid diene polymer, an aliphatic polyolefin oil, a paraffinic oil, an MES oil or their mixtures.
• the mass ratio between the rate of plasticized hydrocarbon resin and the total rate of plasticized hydrocarbon resin and liquid plasticized hydrocarbon agent is greater than 0.4.
• This particular embodiment is also favorable for improving the road behavior of a tire whose tread comprises such a rubber composition.
• the plasticizer system may contain, generally in small quantities, another plasticizing agent other than the plasticizing hydrocarbon resin and the liquid plasticizing agent.
• hydrocarbon useful for the needs of the invention insofar as the desired performance compromise is not altered.
• This other plasticizing agent can for example be an implementation agent traditionally used in small quantities to promote, for example, the dispersion of silica.
• the hydrocarbon plasticizing resin and the liquid hydrocarbon plasticizing agent advantageously represent substantially the main part of the plasticizing system, that is to say the ratio between the level of plasticizing resin hydrocarbon and liquid hydrocarbon plasticizing agent on the level of the total plasticizing system in the rubber composition of layer C1, the levels being expressed in pce is advantageously greater than 0.8, very advantageously greater than 0.9.
• the mass ratio between the rate of reinforcing filler and the total rate of hydrocarbon plasticizing resin and liquid hydrocarbon plasticizing agent is greater than or equal to 1.1, the rates being expressed in pce.
• the C1 layer according to this particular mode brings stiffening within the tread, which improves the road behavior of a tire whose tread has a very adherent surface due to the use of a highly deformable rubber composition intended to come into contact with the ground.
• the rubber composition of layer C1 may also include all or part of the usual additives usually used in elastomer compositions intended for the manufacture of tires, in particular pigments, protective agents such as anti-ozone waxes, chemical anti-ozonants, anti-oxidants, a crosslinking system which can be based either on sulfur, or on sulfur and / or peroxide and / or bismaleimide donors, vulcanization accelerators or retarders, vulcanization activators.
• protective agents such as anti-ozone waxes, chemical anti-ozonants, anti-oxidants, a crosslinking system which can be based either on sulfur, or on sulfur and / or peroxide and / or bismaleimide donors, vulcanization accelerators or retarders, vulcanization activators.
• the actual crosslinking system is preferably a vulcanization system, that is to say based on sulfur and a primary vulcanization accelerator.
• Sulfur is typically provided in the form of molecular sulfur or a sulfur donor, preferably in molecular form. Sulfur in molecular form is also known as molecular sulfur.
• sulfur donor is understood to mean any compound which releases sulfur atoms, combined or not in the form of a polysulphide chain, capable of being inserted into the polysulphide chains formed during vulcanization and bridging the elastomer chains.
• vulcanization activators such as zinc oxide, stearic acid, derivatives guanidiques (in particular diphenylguanidine), etc.
• the sulfur content is preferably between 0.5 and 3.0 phr, that of the primary accelerator is preferably between 0.5 and 5.0 phr.
• accelerators of the sulfenamide type can be used as vulcanization accelerator (primary or secondary). which are primary accelerators, of the thiuram, dithiocarbamate, dithiophosphate, thiourea and xanthat type, as regards secondary accelerators.
• primary accelerators there may be mentioned in particular sulfenamide compounds such as N-cyclohexyl-2-benzothiazyle sulfenamide (“CBS”), N, N-dicyclohexyl-2-benzothiazyle sulfenamide (“DCBS”) , N-ter-butyl-2-benzothiazyl sulfenamide (“TBBS”), and mixtures of these compounds.
• CBS N-cyclohexyl-2-benzothiazyle sulfenamide
• DCBS N-dicyclohexyl-2-benzothiazyle sulfenamide
• TBBS N-ter-butyl-2-benzothiazyl sulfenamide
• the primary accelerator is preferably a sulfenamide, more preferably N-cyclohexyl-2-benzothiazyl sulfenamide.
• secondary accelerators By way of example of secondary accelerators, mention may be made in particular of thiuram disulfides such as tetraethylthiuram disulfide, tetrabutylthiuram disulfide (“TBTD”), tetrabenzylthiuram disulfide (“TBZTD”) and mixtures of these compounds .
• the secondary accelerator is preferably a thiuram disulfide, more preferably tetrabenzylthiuram disulfide.
• Crosslinking if necessary vulcanization, is carried out in a known manner at a temperature generally between 130 ° C and 200 ° C, for a sufficient time which can vary for example between 5 and 90 min in function in particular of the baking temperature, of the crosslinking system adopted and of the crosslinking kinetics of the composition considered.
• the rubber composition, before crosslinking, can be manufactured in suitable mixers, using two successive preparation phases according to a general procedure well known to those skilled in the art: a first working phase or thermo-mechanical kneading (sometimes called “non-productive" phase) at high temperature, up to a maximum temperature between 110 ° C and 190 ° C, preferably between 130 ° C and 180 ° C, followed by a second phase of mechanical work (sometimes referred to as the "productive" phase) at a lower temperature, typically below 110 ° C., for example between 40 ° C. and 100 ° C., the finishing phase during which the sulfur or the sulfur donor is incorporated and the vulcanization accelerator.
• a first working phase or thermo-mechanical kneading sometimes called “non-productive" phase
• a second phase of mechanical work sometimes referred to as the "productive” phase
• the finishing phase during which the sulfur or the sulfur donor is incorporated and the vulcanization accelerator.
• the first (non-productive) phase is carried out in a single thermomechanical step during which, in an appropriate mixer, such as a conventional internal mixer, all the necessary constituents, any additional processing agents and other various additives, with the exception of the crosslinking system.
• the total duration of the kneading, in this non-productive phase is preferably between 1 and 15 min.
• the low temperature is then incorporated, generally in an external mixer such as a cylinder mixer; the whole is then mixed (productive phase) for a few minutes, for example between 2 and 15 min.
• the rubber composition can be calendered or extruded in the form of a sheet or a plate, in particular for characterization in the laboratory, or also in the form of a semi-finished (or profiled) of usable rubber. in a tire.
• the composition can be either in the raw state (before crosslinking or vulcanization), or in the cooked state (after crosslinking or vulcanization), can be a semi-finished product which can be used in a tire.
• the microstructure of the elastomers is determined by 1 H NMR analysis, supplemented by 13 C NMR analysis when the resolution of the 1 H NMR spectra does not allow the allocation and quantification of all the species.
• the measurements are carried out using a BRUKER 500 MHz NMR spectrometer at frequencies of 500.43 MHz for the observation of the proton and 125.83 MHz for the observation of the carbon.
• an HRMAS 4mm z-grad probe is used for the non-soluble elastomers but having the capacity to swell in a solvent. Spectra are acquired at rotational speeds from 4000Hz to 5000Hz.
• a liquid NMR probe is used making it possible to observe the proton and the carbon in decoupled mode from the proton.
• the preparation of the insoluble samples is made in rotors filled with the analyzed material and a deuterated solvent allowing the swelling, in general deuterated chloroform (CDCI3).
• the solvent used must always be deuterated and its chemical nature can be adapted by a person skilled in the art.
• the quantities of material used are adjusted so as to obtain spectra with sufficient sensitivity and resolution.
• soluble samples are dissolved in a deuterated solvent (approximately 25 mg of elastomer in 1 ml), generally deuterated chloroform (CDCI3).
• a deuterated solvent approximately 25 mg of elastomer in 1 ml
• CDCI3 generally deuterated chloroform
• the solvent or solvent mixture used must always be deuterated and its chemical nature can be adapted by a person skilled in the art. In both cases (soluble sample or swollen sample):
• a single pulse sequence of 30 ° is used.
• the spectral window is adjusted to observe all of the resonance lines belonging to the molecules analyzed.
• the number of accumulations is adjusted in order to obtain a signal to noise ratio sufficient for the quantification of each pattern.
• the recycling time between each pulse is adapted to obtain a quantitative measurement.
• a 30 ° single pulse sequence is used with a proton decoupling only during the acquisition to avoid the "Nuclear Overhauser” (NOE) effects and to remain quantitative.
• the spectral window is adjusted to observe all of the resonance lines belonging to the molecules analyzed.
• the number of accumulations is adjusted in order to obtain a signal to noise ratio sufficient for the quantification of each pattern.
• the recycling time between each pulse is adapted to obtain a quantitative measurement.
• the NMR measurements are carried out at 25 ° C.
• the evaluation of the rigidity of the rubber compositions was evaluated by the determination of the dynamic shear modulus G * .
• the response of a sample of vulcanized composition subjected to a sinusoidal alternating shear stress at imposed stress of 0.7 MPa and at a frequency of 10 Hz is recorded at a frequency of temperature, from a minimum temperature below the Tg of the elastomers of the compositions up to a maximum temperature greater than 100 ° C; the values of G * are taken at the temperature of 60 ° C.
• compositions thus obtained are then calendered either in the form of plates (thickness 2 to 3mm) or of thin sheets of rubber for measuring their physical or mechanical properties, or extruded to form, for example, a profile for a tire.
• the five rubber compositions M1 to M5 all contain a copolymer of ethylene and 1,3-butadiene in which the level of ethylene unit is greater than 50%.
• the copolymer carries a silanol or alkoxysilane function at the chain end.
• the copolymer of ethylene and of 1,3-butadiene (EBR) used in the compositions M1 to M4 is prepared according to the following procedure:
• the molar rate in ethylene unit is 79%
• the molar rate in unit 1, 4 is 6%
• the molar rate in unit 1, 2 is 8%
• 2-cyclohexanediyle is 7%.
• the Mooney viscosity is 85.
• the copolymer is prepared according to the same procedure as the EBR copolymer with a difference which is as follows:
• the reactor content is degassed and then the functionalizing agent, (N, N-dimethyl-3-aminopropyl) methyldimethoxysilane, is introduced under an inert atmosphere by overpressure.
• the reaction medium is stirred for 15 minutes and a temperature of 80 ° C. After reaction, the medium is degassed and then precipitated in methanol.
• the polymers are redissolved in toluene, then precipitated in methanol from so as to eliminate the non-grafted “silane” molecules, which makes it possible to improve the quality of the signals of the spectra for the quantification of the function rate and the integration of the different signals.
• the polymer is antioxidized, then dried at 60 ° C under vacuum until constant mass.
• the molar rate in ethylene unit is 76%
• the molar rate in unit 1, 4 is 6%
• the molar rate in unit 1, 2 is 9%
• 2-cyclohexanediyle is 9%.
• the Mooney viscosity is 84.
• Table 1 (1) SBR - 27% styrene; butadiene 1.25%; cis-1, 4 15%; trans-1,480%; Tg -48 ° C;
• Table 2 below presents the values of the ratio between the charge rate and the rate of plasticizer system.
• Table 3 Table 1 above describes a rubber composition T1 presented in document WO 2016/202702, used as a mixture of the second tread layer as well as five compositions in accordance with the invention for mixtures capable of constituting a first layer of tread.
• the rubber composition T1 comprises 100 phr of SBR and has a dynamic shear modulus of 0.9 MPa, which makes this composition capable of providing the tire with excellent adhesion due in particular to a high contact area on rough ground. .
• compositions C1 to C4 in accordance with the invention for the first tread layer comprise 100 phr of the diene elastomer EBR previously described and composition C5 comprises 100 phr of the diene elastomer EBR-F such as previously described.
• compositions have a dynamic shear modulus of between 1.2 and 2.3 MPa, which makes them suitable for stiffening the tread and thus improving the road behavior of the tire, while allowing their use in contact with a rolling floor during wear of the tread.
• composition T1 the charge rates of these compositions are much lower than those of composition T1, which allows a significant reduction in their hysteresis.

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