Rubber composition comprising a highly saturated diene elastomer

Abstract

The present invention relates to a rubber composition based on at least one elastomer matrix comprising predominantly a highly saturated diene elastomer, a reinforcing filler, a vulcanization system and a plasticizing system comprising a hydrocarbon resin having a Tg of between -40°C and 20°C and a number-average molar mass (Mn) of less than or equal to 800 g / mol; the highly saturated diene elastomer being a copolymer of ethylene and at least one 1,3-diene in which the ethylene units represent at least 50 mol% of the monomer units of the copolymer.

Description

Title of the invention: Rubber composition comprising a highly saturated diene elastomer Technical field

[0001] The field of the present invention is that of rubber compositions based on highly saturated diene elastomer intended for use in a tire, in particular in its tread. Prior art

[0002] The use of highly saturated diene elastomer is known in the prior art. For example, the Applicant has described copolymers of ethylene and 1,3-butadiene and their application in a tire tread in document WO2014114607A1. This document indicates that the use of these copolymers has the effect of conferring good wear resistance and rolling resistance properties to the tire.

[0003] In the field of plasticizers and in particular plasticizing resins, certain documents of the Applicant mention the use of low Tg resins as plasticizers in rubber compositions for tires based on an SBR type elastomer in order to shift the balance existing between various performances sought for the tire, including rolling resistance, adhesion on dry ground, adhesion on wet ground, and to optimize the hardness of the cured rubber compositions at the same time as their raw viscosity. We can thus cite documents WO2015 / 124684 A1 and WO2015 / 124681 A1

[0004] Nevertheless, manufacturers are still looking for solutions to improve tire performance or shift their balance. In the area discussed above of tires comprising a highly saturated diene elastomer in the tread, there is still a need for rubber compositions that give the tire improved rolling resistance properties without penalizing other properties such as road grip. Statement of the invention

[0005] The Applicant has found a rubber composition which makes it possible to meet this need in the field of application of highly saturated diene elastomers to rubber compositions for the tire and in particular for the tread. In particular, the Applicant has found a rubber composition which combines the use of a highly saturated diene elastomer with the use of a low Tg resin, and which gives the tire, against all expectations, good rolling resistance properties and a compromise of rolling resistance properties. rolling / grip on offset wet ground, notably with improved wet grip properties compared to the combined use of an SBR type diene elastomer with a low Tg resin.

[0006] Thus, a first object of the invention is a rubber composition based on at least

[0007] - an elastomer matrix comprising mainly a highly saturated diene elastomer, - a reinforcing charge, - a vulcanization system and - a plasticizing system comprising a low Tg resin.

[0008] Another subject of the invention is a pneumatic or non-pneumatic tire which comprises a rubber composition in accordance with the invention, preferably in its tread. Summary of the invention

[0009] The invention, described in more detail below, has as its subject at least one of the embodiments listed in the following points:

[0010] 1. Rubber composition based on at least - an elastomer matrix comprising mainly a highly saturated diene elastomer, which highly saturated diene elastomer is a copolymer of ethylene and at least one 1,3-diene in which the ethylene units represent at least 50 mol% of the monomer units of the copolymer, - a reinforcing charge, - a vulcanization system and - a plasticizing system comprising a low Tg (glass transition temperature) hydrocarbon resin, optionally hydrogenated, having a Tg between -40°C and 20°C and a number-average molar mass (Mn) of less than 800 g / mol.

[0011] 2. Rubber composition according to embodiment 1, in which the ethylene units represent between 50% and 95% by mole of the monomer units of the highly saturated diene copolymer.

[0012] 3. Rubber composition according to any one of the preceding embodiments, wherein the ethylene units represent at least 65 mol% of the monomer units of the highly saturated diene copolymer, preferably from 65% to 90 mol% of the monomer units of the copolymer.

[0013] 4. Rubber composition according to any one of the preceding embodiments, wherein the at least one 1,3-diene is 1,3-butadiene, isoprene, myrcene or farnesene, preferably 1,3-butadiene.

[0014] 5. Rubber composition according to any one of the preceding embodiments, wherein the copolymer of ethylene and at least one 1,3-diene is a copolymer of ethylene and 1,3-butadiene.

[0015] 6. Rubber composition according to any one of the preceding embodiments, in which the copolymer is random.

[0016] 7. Rubber composition according to any one of the preceding embodiments, in which the level of highly saturated diene elastomer in the rubber composition varies in a range from 60 to 100 phr, preferably from 80 to 100 phr and very preferably from 90 to 100 phr.

[0017] 8. Composition according to any one of the preceding embodiments in which the hydrocarbon resin rate of Tg between -40°C and 20°C is within a range of 20 to 120 pce, preferably 40 to 110 pce.

[0018] 9. Composition according to any one of the preceding embodiments in which the hydrocarbon resin with a Tg between -40°C and 20°C is a predominantly styrenic and hydrogenated resin.

[0019] 10. Composition according to any one of the preceding embodiments in which the hydrocarbon resin previously mentioned as hydrocarbon resin with a Tg of between -40°C and 20°C has a Tg of between -40°C and 0°C, more preferably between -40°C and -20°C.

[0020] 11. Composition according to any one of the preceding embodiments in which the hydrocarbon resin previously mentioned as hydrocarbon resin with a Tg of between -40°C and 20°C has a Tg ranging from -35°C to -25°C.

[0021] 12. Composition according to any one of the preceding embodiments in which the hydrocarbon resin previously mentioned as hydrocarbon resin with a Tg between -40°C and 20°C has a number-average molar mass greater than or equal to 250 g / mol and less than 600 g / mol.

[0022] 13. Composition according to any one of the preceding embodiments in which the hydrocarbon resin previously mentioned as hydrocarbon resin with a Tg between -40°C and 20°C has a polydispersity index value (PI = Mw / Mn) of at most 1.60, preferably at most 1.40.

[0023] 14. Composition according to any one of the preceding embodiments in which the hydrocarbon resin previously mentioned as hydrocarbon resin with a Tg between -40°C and 20°C has an aliphatic proton level measured by NMR (standard method) of at least 90%, preferably at least 95%.

[0024] 15. Composition according to any one of the preceding embodiments in which the hydrocarbon resin previously mentioned as hydrocarbon resin with Tg between -40°C and 20°C has an aromatic proton rate lower than 5%.

[0025] 16. Composition according to the preceding embodiment in which the resin has a aromatic proton level ranging from 0% to 4%, preferably from 0% to 2%.

[0026] 17. Composition according to any one of the preceding embodiments in which the resin has an ethylenic proton rate of less than 5%.

[0027] 18. Composition according to any one of the preceding embodiments in which the resin has an ethylenic proton rate of less than or equal to 3%.

[0028] 19. Composition according to any one of the preceding embodiments in which the hydrocarbon resin previously mentioned as hydrocarbon resin with a Tg of between -40°C and 20°C has a softening point in a range from +10 to 70°C, preferably from 10 to 40°C, more preferably from 10 to 30°C, preferably from 15 to 25°C.

[0029] 20. Composition according to any one of the preceding embodiments in which the plasticizing system further comprises at least one plasticizing oil or at least one hydrocarbon resin with a Tg greater than 20°C, or at least one plasticizing oil and a hydrocarbon resin with a Tg greater than 20°C.

[0030] 21. Composition according to any one of the preceding embodiments in which the total rate of plasticizers constituting the plasticizing system is greater than or equal to 25 pce, preferably within a range from 40 to 110 pce.

[0031] 22. Composition according to the preceding embodiment in which the total rate of plas The amount of the plasticizers constituting the plasticizing system is in the range from 40 to 100 pce, preferably from 40 to 90 pce.

[0032] 23. Composition according to any one of the preceding embodiments in which the reinforcing filler comprises at least one silica, one carbon black or a mixture of silica and carbon black.

[0033] 24. Composition according to any one of the preceding embodiments in which the reinforcing filler includes silica as the majority reinforcing filler.

[0034] 25. Composition according to any one of the preceding embodiments in which the reinforcing filler rate is within a range from 5 to 200 pce, preferably from 40 to 160 pce.

[0035] 26. Composition according to any one of the preceding embodiments in which the silica content is in the range of 50 to 160 pce.

[0036] 27. Pneumatic or non-pneumatic tire comprising a composition according to any of the previous achievements.

[0037] 28. Pneumatic or non-pneumatic tire according to the previous embodiment comprising a composition according to any one of embodiments 1 to 26 in all or part of its tread. Definitions

[0038] By the expression "composition based on", we mean a composition comprising the mixture and / or the in situ reaction product of the different constituents used, some of these constituents being able to react and / or being intended to react with each other, at least partially, during the different phases of manufacturing the composition; the composition thus being able to be in a totally or partially crosslinked state or in a non-crosslinked state.

[0039] By the expression "part by weight per hundred parts by weight of elastomer" (or pce), it is meant, within the meaning of the present invention, the part, by mass per hundred parts by mass of elastomer.

[0040] In this document, unless expressly indicated otherwise, all percentages (%) indicated are percentages (%) by mass.

[0041] On the other hand, any interval of values ​​designated by the expression "between a and b" represents the range of values ​​from more than a to less than b (i.e., excluding limits a and b), while any interval of values ​​designated by the expression "from a to b" means the range of values ​​from a to b (i.e., including the strict limits a and b). In the present document, when an interval of values ​​is designated by the expression "from a to b", the interval represented by the expression "between a and b" is also and preferably designated.

[0042] In the present application, the term "all the monomer units of the elastomer" or "all the monomer units of the elastomer" means all 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 as a molar percentage calculated on the basis of all the monomer units of the elastomer.

[0043] When a "majority" compound is referred to, within the meaning of the present invention, this compound is the majority among the compounds of the same type in the composition, that is to say that it is the one which represents the largest quantity by mass among the compounds of the same type. Thus, for example, a majority elastomer is the elastomer representing the largest mass relative to the total mass of the elastomers in the composition. In the same way, a so-called majority filler is the one representing the largest mass among the fillers in the composition. For example, in a system comprising a single elastomer, this is the majority within the meaning of the present invention; and in a system comprising two elastomers, the majority elastomer represents more than half of the mass of the elastomers. On the contrary, a "minority" compound is a compound which does not represent the largest mass fraction among the compounds of the same type.Preferably, by majority, we mean a mass proportion of more than 50%; when the compound represents 100% by mass, it is also referred to as “majority”.

[0044] The compounds mentioned in the description may be of fossil origin or bio-sourced. In the latter case, they may be partially or totally derived from biomass or obtained from renewable raw materials derived from biomass. Similarly, the compounds mentioned may also come from the recycling of materials already in use, i.e. they may be partially or totally derived from a recycling process, or obtained from raw materials themselves derived from a recycling process. This includes polymers, plasticizers, fillers, etc.

[0045] Unless otherwise indicated, as is the case in the examples presented below, the glass transition temperature (Tg) values ​​described herein are measured in a known manner by DSC (Differential Scanning Calorimetry) according to ASTM D3418 (1999). Detailed description of the invention 1-1 Elastomeric matrix

[0046] By "elastomer matrix" is meant all of the elastomers in the composition.

[0047] According to the invention, the elastomer matrix predominantly comprises at least one highly saturated diene elastomer, namely a copolymer containing ethylene units and diene units (hereinafter referred to as "the copolymer").

[0048] The highly saturated diene elastomer, useful for the purposes of the invention, is a copolymer, preferably a random one, which comprises ethylene units resulting from the polymerization of ethylene. In a known manner, the expression "ethylene unit" refers to the unit -(CH2-CH2)- resulting from the insertion of ethylene into the elastomer chain. The highly saturated diene elastomer is rich in ethylene units, since the ethylene units represent at least 50 mol% of all the monomer units of the elastomer and at most 95 mol%.

[0049] Preferably, the highly saturated diene elastomer comprises at least 65 mol% of ethylene units. In other words, the ethylene units preferably represent at least 65 mol% of all the monomer units of the highly saturated diene elastomer. More preferably, the highly saturated diene elastomer comprises from 65% to 90 mol% of ethylene units, molar percentage calculated on the basis of all the monomer units of the highly saturated diene elastomer.

[0050] The highly saturated diene elastomer being a copolymer of ethylene and at least one 1,3-diene also comprises 1,3-diene units resulting from the polymerization of at least one 1,3-diene. In a known manner, the expression "1,3-diene unit" refers to the units resulting from the insertion of the 1,3-diene.

[0051] The 1,3-diene units are those for example of a 1,3-diene having 4 to 24 atoms of carbon.

[0052] Suitable 1,3-dienes include butadiene, isoprene, 2,3-di(C 1 -C 5 alkyl)-1,3-butadiene such as, 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, aryl-1,3-butadiene such as phenyl-1,3-butadiene, 1,3-pentadiene. Also suitable as 1,3-diene is a 1,3-diene of formula CH2=CR-CH=CH2, in which R represents a hydrocarbon chain having 3 to 20 carbon atoms, such as for example a linear monoterpene (Ci0H16), like myrcene, a linear sesquiterpene (Ci5H24), like famesene etc....

[0053] The highly saturated diene elastomer is preferably a copolymer of ethylene and at least one 1,3-diene from among 1,3-butadiene, isoprene, myrcene and farnesene.

[0054] Preferably, the at least one 1,3-diene is 1,3-butadiene or isoprene, more preferably 1,3-butadiene, in which case the highly saturated diene elastomer is a copolymer of ethylene and 1,3-butadiene, preferably random.

[0055] The highly saturated diene elastomer useful for the purposes of the invention can be obtained according to different synthesis methods known to 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. In this respect, mention may be made of catalytic systems based on metallocene complexes, which catalytic systems are described in documents EP 1 092 731, WO 2004035639, WO 2007054223 and WO 2007054224, as well as WO2020070442, WO2020070443 and WO2020074804 in the name of the Applicant.The highly saturated diene elastomer, including when it is random, can also be prepared by a process using a preformed type catalytic system such as those described in documents WO 2017093654 A1, WO 2018020122 A1 and WO 2018020123 A1. The highly saturated diene elastomer is random according to one embodiment of the invention.

[0056] The highly saturated diene elastomer useful for the purposes of the invention may consist of a mixture of highly saturated diene elastomers which differ from one another by their microstructures or by their macrostructures.

[0057] According to the invention, the level of the highly saturated diene elastomer in the rubber composition is preferably at least 50 parts by weight per hundred parts of elastomer of the rubber composition (phr). More preferably, the level of the highly saturated diene elastomer in the rubber composition varies in a range from 60 to 100 phr, preferably 80 to 100 phr. More preferably, it varies in a range from 90 to 100 phr.

[0058] As a complement, the elastomer matrix of the composition of the invention may comprise at least one other elastomer, in a minority. Particularly noteworthy are the diene elastomers known to those skilled in the art for their use in the field of tires, such as a polybutadiene (abbreviated as "BR"), a synthetic polyisoprene (IR), natural rubber (NR), a butadiene copolymer such as a butadiene-styrene copolymer (SBR), an isoprene copolymer and mixtures of these elastomers. 1-2 Specific plasticizer

[0059] Low Tg resin

[0060] The composition of the invention comprises at least one hydrocarbon resin having a Tg in a range from -40°C to 20°C, i.e. viscous at 20°C, known as "low Tg" and a number-average molar mass (Mn) less than or equal to 800 g / mol.

[0061] Preferably, the low Tg hydrocarbon plasticizing resin has at least one of the following characteristics:

[0062] - a Tg between -40°C and 0°C, more preferably between -40°C and -20°C, and more preferably still between -35°C and -25°C;

[0063] - a number-average molar mass (Mn) greater than or equal to 150 g / mol, of preferably greater than or equal to 250 g / mol and less than or equal to 600 g / mol, more preferably greater than or equal to 250 g / mol and less than or equal to 500 g / mol;

[0064] - a polydispersity index value (PI = Mw / Mn) of at most 1.60, preferably initially of at most 1.40.

[0065] Also preferably, the low Tg hydrocarbon plasticizing resin has a softening point in a range from 10 to 70°C, preferably from 10 to 40°C, more preferably from 10 to 30°C, preferably from 15 to 25°C;

[0066] More preferably, this low Tg hydrocarbon plasticizing resin has all of the above preferred characteristics.

[0067] The softening point is measured according to ISO 4625 ("Ring and Bail" method). The Tg is measured according to ASTM D3418 (1999). The macro structure (Mw, Mn and Ip) of the hydrocarbon resin is determined by size exclusion chromatography (SEC): tetrahydrofuran solvent; temperature 35°C; concentration 1 g / l; flow rate 1 ml / min; solution filtered on a 0.45 inp porosity filter before injection; Moore calibration with polystyrene standards; set of 3 "WATERS" columns in series ("STYRAGEL" HR4E, HR1 and HR0.5); detection by differential refractometer ("WATERS 2410") and its associated operating software ("WATERS EMPOWER").

[0068] The hydrocarbon resins according to the invention can be aliphatic, or aro matic or of the mixed aliphatic / aromatic type, that is to say that the hydrocarbon resins according to the invention comprise aliphatic constitutional units, aromatic constitutional units, or aliphatic constitutional units and aromatic constitutional units. They can be natural or synthetic, petroleum-based or not (if this is the case, also known as petroleum resins).

[0069] The hydrocarbon resins according to the invention may be derived from the polymerization of one or more monomers among aromatic monomers and aliphatic monomers. The hydrocarbon resins may have undergone partial or total hydrogenation at the end of the polymerization.

[0070] According to one embodiment, the low Tg hydrocarbon plasticizing resin according to the invention is chosen from the group consisting of cyclopentadiene (abbreviated CPD) or dicyclopentadiene (abbreviated DCPD) homopolymer or copolymer resins, terpene homopolymer or copolymer resins, terpene phenol homopolymer or copolymer resins, C5-cut homopolymer or copolymer resins, styrene homopolymer or copolymer resins, C9-cut homopolymer or copolymer resins (or more generally a C8 to C10 cut), and mixtures of these resins. The term "terpene" here includes, in a known manner, alpha-pinene, beta-pinene and limonene monomers.

[0071] According to a preferred embodiment, the hydrocarbon resin useful for the purposes of the invention is a hydrocarbon resin based on one or more aromatic monomers. Suitable aromatic monomers include, for example, styrene, alpha-methylstyrene, ortho-, meta-, para-methylstyrene, vinyl toluene, para-tert-butylstyrene, methoxystyrenes, chlorostyrenes, vinyl mesitylene, divi-nylbenzene, vinyl naphthalene, any vinyl aromatic monomer derived from a C9 cut (or more generally from a C8 to C10 cut). Preferably, the vinyl aromatic monomer is styrene or a vinyl aromatic monomer derived from a C9 cut (or more generally from a C8 to C10 cut). According to this embodiment, the hydrocarbon resin may be partially or fully hydrogenated, forming an aliphatic / aromatic or aliphatic hydrocarbon resin.

[0072] According to an even more preferred embodiment, the hydrocarbon resin useful for the purposes of the invention is a resin mainly based on styrene and hydrogenated. Such a resin is for example a hydrogenated resin based on styrene, as the majority monomer, and vinyl toluene.

[0073] According to one embodiment of the invention, the low Tg hydrocarbon resin has an aliphatic proton content of at least 90%, preferably at least 95%.

[0074] According to a preferred embodiment, the hydrocarbon resin useful for the purposes of the invention has an aromatic proton content of less than 5%, preferably included in a range from 0% to 4%, preferably from 0% to 2%.

[0075] According to a preferred embodiment, the hydrocarbon resin useful for the purposes of the invention has an ethylenic proton content of less than 5%, preferably within a range from 0% to 3%.

[0076] The aromatic proton rate (%HA) and the ethylenic proton rate (%HE) are measured by 1 H NMR. This determination is carried out relative to all the detected signals. Thus, the results obtained are expressed in % of peak area.

[0077] The samples are solubilized in deuterated chloroform (CDCl3) at a rate of approximately 10 mg of resin in approximately 1 mL of solvent. The spectra are acquired on a Bruker Avance 500 MHz spectrometer equipped with a Bruker BBO z-grad 5 mm "broadband" probe. The 1 H NMR experiment uses a single 30° pulse sequence and a repetition delay of 5 seconds between each acquisition. 64 accumulations are carried out at room temperature. The chemical shifts are calibrated relative to the protonated impurity of deuterated chloroform; 6 ppm 1 H at 7.20 ppm. The 1 H NMR signals of the aromatic protons are located between 8.5 ppm and 6.2 ppm. The ethylenic protons generate signals between 6.2 ppm and 4.5 ppm. Finally, the signals corresponding to aliphatic protons are located between 4.5 ppm and Oppm. The areas of each category of protons are reported to the sum of these areas to give a distribution in % of area of ​​each category of protons.

[0078] Resins that can be used in the context of the invention are commercially available, for example sold by the company CRAY VALLEY under the name “Wingtack 10” (aliphatic resin of Mn=483 g / mol; Mw=595 g / mol; lp=1.2; softening point 10°C; Tg=-28°C), or by the company Eastman under the name “Regalrez 1018” (aliphatic resin of Mn=360 g / mol; Mw=464 g / mol; lp=1.3; softening point 20°C; Tg=-23°C),

[0079] The content of low Tg hydrocarbon plasticizing resin is greater than or equal to 20 pce, preferably within a range from 20 pce to 120 pce, preferably from 40 pce to 110 pce, or even from 45 to 90 pce. Indeed, below 20 pce of low Tg resin, the composition could present problems of high viscosity and therefore of industrial processability.

[0080] The low Tg hydrocarbon plasticizing resin may be a mixture of several low Tg hydrocarbon plasticizing resins as described above.

[0081] The plasticizing system according to the invention may comprise, in addition to the low Tg hydrocarbon plasticizing resin, at least one plasticizing oil or at least one hydrocarbon resin with a Tg greater than 20°C, or at least one plasticizing oil and one hydrocarbon resin with a Tg greater than 20°C. These plasticizers are well known to those skilled in the art and are commercially available.

[0082] The total level of plasticizers (low Tg hydrocarbon plasticizing resin, oil plasticizer, hydrocarbon resin with a Tg greater than 20°C) constituting the plasticizing system is greater than or equal to 25 pce, preferably within a range from 40 to 110 pce. According to certain embodiments, the total level of plasticizers constituting the plasticizing system is within a range from 40 to 100 pce, preferably within a range from 40 to 90 pce. 1-3 Reinforcing load

[0083] The composition according to the invention comprises a reinforcing filler. Any type of reinforcing filler known for its ability to reinforce a rubber composition suitable for the manufacture of tires may be used, for example an organic filler such as carbon black, a reinforcing inorganic filler such as silica, alumina, or a blend of these two types of filler. More particularly, the reinforcing filler comprises at least one silica, one carbon black or a mixture of silica and carbon black.

[0084] Suitable carbon blacks are all carbon blacks, in particular so-called pneumatic grade blacks. Among the latter, mention will be made more particularly of reinforcing carbon blacks of the 100, 200 or 300 series (ASTM grades), such as blacks NI 15, N134, N234, N326, N330, N339, N347, N375, or even, depending on the intended applications, blacks of higher series (for example N660, N683, N772). The carbon blacks could, for example, already be incorporated into an isoprene elastomer in the form of a masterbatch (see for example applications WO 97 / 36724 or WO 99 / 16600).

[0085] Examples of organic fillers other than carbon blacks that may be mentioned are functionalized polyvinyl organic fillers as described in applications WO-A-2006 / 069792, WO-A-2006 / 069793, WO-A-2008 / 003434 and WO-A-2008 / 003435.

[0086] The composition may contain one type of silica or a blend of several silicas. The silica used may be any reinforcing silica known to those skilled in the art, in particular any precipitated or pyrogenic silica having a BET surface area and a CTAB specific surface area both less than 450 m2 / g, preferably from 30 to 400 m2 / g. Examples of highly dispersible precipitated silicas (known as "HDS") include "Ultrasil 7000" and "Ultrasil 7005" silicas from Degussa, "Zeosil" 1165MP, 1135MP and 1115MP silicas from Solvay, "Hi-Sil EZ150G" silica from PPG, "Zeopol" 8715, 8745 and 8755 silicas from Huber, treated precipitated silicas such as, for example, the aluminum-doped silicas described in application EP-A-0735088 or the high specific surface silicas as described in application WO 03 / 16837.

[0087] The composition according to the invention may optionally also contain coupling agents, coupling activators, inor charge recovery agents organic or more generally processing aids capable in a known manner, thanks to an improvement in the dispersion of the filler in the rubber matrix and a reduction in the viscosity of the composition, of improving its processability in the raw state, these agents being for example hydrolyzable silanes such as alkylalkoxysilanes, polyols, fatty acids, polyethers, primary, secondary or tertiary amines, hydroxylated or hydrolyzable polyorganosiloxanes. It is possible to use in particular polysulfurized silanes, called "symmetrical" or "asymmetrical" according to their particular structure, as described for example in applications WO03 / 002648 (or US 2005 / 016651) and WO03 / 002649 (or US 2005 / 016650).

[0088] In the rubber composition in accordance with the invention, the content of coupling agent is preferably between 1 and 15 pce.

[0089] Those skilled in the art will understand that, as a filler equivalent to the silica described in this paragraph, a reinforcing filler of another nature, in particular organic, could be used, provided that this reinforcing filler is covered with a layer of silica, or else comprises functional sites on its surface, in particular hydroxylated sites, requiring the use of a coupling agent to establish the bond between the filler and the elastomer.

[0090] The physical state in which the reinforcing filler is present is indifferent, whether in the form of powder, microbeads, granules, beads or any other suitable densified form.

[0091] For the purposes of the invention, the total reinforcing filler content (carbon black and / or reinforcing inorganic filler such as silica) is from 5 to 200 phr, more preferably from 40 to 160 phr. Below 5 phr of filler, the composition may not be sufficiently reinforced, while above 200 phr of filler, the composition may be less effective in rolling resistance.

[0092] Preferably, silica is used as the majority filler, preferably at a rate ranging from 50 to 160 phr, more preferably from 60 to 150 phr; and optionally carbon black. Carbon black, when present, is then used in a minor manner, preferably at a rate in a range ranging from 0.1 to 10 phr, more preferably from 0.5 to 10 phr, in particular from 1 to 5 phr. 1-4 Crosslinking system

[0093] The crosslinking system may be any type of system known to those skilled in the art in the field of tire rubber compositions. It may in particular be based on sulfur, and / or peroxide and / or bismaleimides.

[0094] Preferably, the crosslinking system is sulfur-based, in which case it is referred to as a vulcanization system. The sulfur can be provided in any form, in particular in the form of molecular sulfur, or a sulfur-donating agent. at least one vulcanization accelerator is also preferably present, and, optionally, also preferably, various known vulcanization activators may be used such as zinc oxide, stearic acid or equivalent compound such as stearic acid salts and transition metal salts, guanidine derivatives (in particular diphenylguanidine), or even known vulcanization retarders.

[0095] The sulfur is used at a preferential rate of between 0.2 pce and 10 pce, more preferably between 0.3 and 5 pce. The vulcanization accelerator or mixture of accelerators is used at a preferential rate of between 0.5 and 10 pce, more preferably between 0.5 and 5 pce.

[0096] Any compound capable of acting as an accelerator for the vulcanization of diene elastomers in the presence of sulfur may be used as an accelerator, in particular accelerators of the thiazole type and their derivatives, accelerators of the sulfenamide, thiuram, dithiocarbamate, dithiophosphate, thiourea and xanthate types. Examples of such accelerators include, but are not limited to, the following compounds: 2-mercaptobenzothiazyl disulfide (abbreviated as "MBTS"), N-cyclohexyl-2-benzothiazyl sulfenamide ("CBS"), N,N-dicyclohexyl-2-benzothiazyl sulfenamide ("DCBS"), N-tert-butyl-2-benzothiazyl sulfenamide ("TBBS"), N-tert-butyl-2-benzothiazyl sulfenimide ("TBSI"), tetrabenzylthiuram disulfide ("TBZTD"), zinc dibenzyldithiocarbamate ("ZBEC") and mixtures of these compounds. 1-5 Possible additives

[0097] The rubber composition according to the invention may optionally also comprise all or part of the usual additives usually used in elastomer compositions for tires, pigments, protective agents such as anti-ozone waxes, chemical anti-ozonants, antioxidants, anti-fatigue agents, reinforcing resins (as described for example in application WO 02 / 10269).

[0098] It goes without saying that the invention relates to the rubber compositions previously described both in the so-called "raw" or non-crosslinked state (i.e., before curing) and in the so-called "cured" or crosslinked, or even vulcanized state (i.e., after crosslinking or vulcanization).

[0099] 1-6 Preparation of the rubber composition

[0100] The composition in accordance with the invention can be manufactured in suitable mixers, using two successive preparation phases well known to those skilled in the art: - a first phase of thermomechanical working or mixing (so-called "non-productive" phase), which can be carried out in a single thermomechanical step during which all the necessary constituents are introduced into a suitable mixer such as a standard internal mixer (for example of the 'Banbury' type), in particular the elastomeric matrix, the reinforcing filler, any other miscellaneous additives, with the exception of the crosslinking system. The incorporation of the possible filler into the elastomer can be carried out in one or more stages by thermomechanically mixing. In the case where the filler is already incorporated in whole or in part into the elastomer in the form of a masterbatch as described for example in applications WO 97 / 36724 or WO 99 / 16600, it is the masterbatch which is directly mixed and where appropriate the other elastomers or fillers present in the composition which are not in the form of a masterbatch are incorporated, as well as any other miscellaneous additives other than the crosslinking system. The non-productive phase can be carried out at high temperature, up to a maximum temperature between 110°C and 200°C, preferably between 130°C and 185°C, for a duration generally between 2 and 10 minutes.

[0101] - a second phase of mechanical work (so-called “productive” phase), which is carried out in an external mixer such as a roller mixer, after cooling the mixture obtained during the first non-productive phase to a lower temperature, typically below 120°C, for example between 40°C and 100°C. The crosslinking system is then incorporated, and the whole is then mixed for a few minutes, for example between 5 and 15 min.

[0102] Such phases are well known to those skilled in the art.

[0103] The final composition thus obtained is then calendered, for example, in the form of a sheet or plate, in particular for laboratory characterization, or extruded (or co-extruded with another rubber composition) in the form of a semi-finished (or profiled) rubber usable, for example, as a tire tread. These products can then be used for the manufacture of tires, according to techniques known to those skilled in the art.

[0104] The composition may be either in the raw state (before crosslinking or vulcanization), or in the cured state (after crosslinking or vulcanization), and may be a semi-finished product which may be used in a tire.

[0105] The crosslinking (or curing), where appropriate the vulcanization, is carried out in a known manner at a temperature generally between 130°C and 200°C, for a sufficient time which may vary for example between 5 and 90 min depending in particular on the curing temperature, the crosslinking system adopted and the crosslinking kinetics of the composition considered. 1-7 Pneumatic

[0106] The present invention also relates to a pneumatic or non-pneumatic tire comprising a rubber composition according to the invention.

[0107] Preferably, the composition according to the invention is present at least in the tread of the pneumatic or non-pneumatic tire according to the invention.

[0108] The aforementioned characteristics of the present invention, as well as others, will be better understood upon reading the following description of several exemplary embodiments of the invention, given for illustrative and non-limiting purposes. II. EXAMPLES OF CARRYING OUT THE INVENTION II. 1 Tests and measurements:

[0109] IL 1-1 Determination of the microstructure of elastomers:

[0110] The microstructure of the elastomers is determined by 'H NMR analysis, supplemented by 13C NMR analysis when the resolution of the 'H NMR spectra does not allow the attribution and quantification of all the species. The measurements are carried out using a BRUKER 500MHz NMR spectrometer at frequencies of 500.43 MHz for proton observation and 125.83MHz for carbon observation.

[0111] For non-soluble elastomers but having the capacity to swell in a solvent, a 4mm z-grad HRMAS probe is used to observe the proton and carbon in proton-decoupled mode. The spectra are acquired at rotation speeds of 4000Hz to 5000Hz.

[0112] For measurements on soluble elastomers, a liquid NMR probe is used to observe the proton and carbon in proton-decoupled mode.

[0113] The preparation of non-soluble samples is carried out in rotors filled with the analyzed material and a deuterated solvent allowing swelling, generally deuterated chloroform (CDCl3). The solvent used must always be deuterated and its chemical nature can be adapted by those skilled in the art. The quantities of material used are adjusted so as to obtain spectra with sufficient sensitivity and resolution.

[0114] The soluble samples are dissolved in a deuterated solvent (approximately 25 mg of elastomer in 1 ml), generally deuterated chloroform (CDCl3). The solvent or solvent blend used must always be deuterated and its chemical nature can be adapted by those skilled in the art.

[0115] In both cases (soluble sample or swollen sample):

[0116] For proton NMR, a single 30° pulse sequence is used. The spectral window is adjusted to observe all the resonance lines belonging to the molecules analyzed. The accumulation number is adjusted to obtain a sufficient signal-to-noise ratio for the quantification of each pattern. The recycling time between each pulse is adapted to obtain a quantitative measurement.

[0117] For carbon NMR, a single 30° pulse sequence is used with proton decoupling only during acquisition to avoid "Nuclear Overhauser" (NOE) effects and to remain quantitative. The spectral window is adjusted to observe all the resonance lines belonging to the molecules analyzed. The accumulation number is adjusted to obtain a sufficient signal-to-noise ratio for quantification of each pattern. The recycling time between each pulse is adapted to obtain a quantitative measurement.

[0118] NMR measurements are carried out at 25°C. II. 1-2 Measurement of dynamic properties: Dynamic properties

[0119] The dynamic properties G* and tan(ô)max are measured on a viscoanalyzer (Metravib V A4000), according to the ASTM D5992-96 standard. The response of a sample of vulcanized composition (cylindrical specimen 2 mm thick and 79 mm2 in cross-section), subjected to sinusoidal stress in alternating simple shear, at a frequency of 10 Hz, is recorded. A temperature sweep is carried out from -80°C to + 100°C with a ramp of +1.5°C / min, under a maximum stress of 0.7 MPa. The value of the tangent of the loss angle (tan(ô)) at 0°C is then recorded.

[0120] The following results are derived from measurements using temperature scans under a given stress and deformation scans, at a stress frequency of 10 Hz.

[0121] Strain hysteresis is determined by taking the maximum value of the loss angle on a return scan from a 40°C strain scan ranging from 0.01% to 100% peak-peak strain. This measurement is a descriptor of the hysteresis and therefore an indication of the rolling resistance property of the tire. The value in base 100 is calculated according to the operation: (tan(ô) value at 40°C of the control / tan(ô) value at 40°C of the sample) * 100. In this way, a lower value represents a decrease in hysteresis performance (i.e., an increase in hysteresis) while a higher value represents a better hysteresis performance (i.e., a lower hysteresis).

[0122] Similarly, the hysteresis at 0°C is determined on a temperature scan as defined above. This measurement is a descriptor of the low temperature hysteresis and therefore an indication of the wet grip property. The value in base 100 is calculated according to the operation: (tan(ô) value at 0°C of the sample / tan(ô) value at 0°C of the control) * 100. In this way, a lower value represents a decrease in hysteresis performance (i.e., a decrease in wet grip) while a higher value represents a better hysteresis performance (i.e., a better wet grip performance). II.2 Preparation of rubber compositions:

[0123] The rubber compositions, the formulation details of which are shown in Table 1, were prepared in the following manner:

[0124] The elastomer is introduced into an internal mixer (final filling rate: approximately 70% by volume), whose initial tank temperature is approximately 90°C. When the temperature reaches 100°C, half of the silica and resin are introduced, as well as the carbon black and the coupling agent. The other half of the silica and resin, the oil and the various other ingredients except for the sulfur and the vulcanization accelerators, are introduced at 120°C. Thermomechanical work (non-productive phase) is then carried out in one step, which lasts a total of approximately 3 to 4 min, until a maximum "drop" temperature of 160°C is reached. The resulting mixture is recovered, cooled and then the sulphur and vulcanisation accelerators are incorporated into a mixer (homo-finisher) at 30°C, mixing everything (productive phase) for an appropriate time (for example around ten minutes).

[0125] The compositions thus obtained are then calendered either in the form of plates (thickness 2 to 3 mm) or thin sheets of rubber for the measurement of their physical or mechanical properties, or extruded in the form of a tire tread. Preparation of the elastomer

[0126] The elastomer (EBR) is prepared according to the following procedure:

[0127] 30 mg of metallocene [{Me2SiFlu2Nd(p-BH4)2Li(THF)}2, the symbol Flu re having the fluorenyl group of formula C13H8] are introduced into a first Steinie bottle in a glove box. The co-catalyst, butyloctylmagnesium previously dissolved in 300 ml of methylcyclohexane in a second Steinie bottle, is introduced into the first Steinie bottle containing the metallocene in the following proportions: 0.00007 mol / L of metallocene, 0.0004 mol / L of co-catalyst. After 10 minutes of contact at room temperature, a catalytic solution is obtained. The catalytic solution is then introduced into the polymerization reactor. The temperature in the reactor is then increased to 80°C. When this temperature is reached, the reaction starts by injecting a gaseous mixture of ethylene and 1,3-butadiene (80 / 20 mol%) into the reactor. The polymerization reaction takes place at a pressure of 8 bars. The proportions of metallocene and co-catalyst are 0.00007 mol / L and 0.0004 mol / L respectively.The polymerization reaction is stopped by cooling, degassing the reactor and adding ethanol. An antioxidant is added to the polymer solution. The copolymer is recovered by drying in a vacuum oven. In a reactor containing methylcyclohexane, ethylene and butadiene at 80°C in the proportions (80 / 20% mol Ethylene / butadiene), butyloctylmagnesium (BOMAG) is added to neutralize the impurities in the reactor, then the catalytic system. At this time, the reaction temperature is regulated at 80°C and the polymerization reaction starts. The polymerization reaction takes place at a constant pressure of 8 bars. The reactor is fed. throughout the polymerization into ethylene and butadiene in the proportions 80 / 20% mol (Ethylene / Butadiene). The polymerization reaction is stopped by cooling, degassing the reactor and adding ethanol. An antioxidant is added to the polymer solution. The copolymer is recovered by drying in a vacuum oven until constant mass.

[0128] The catalytic system is a preformed catalytic system. It is prepared in methylcyclohexane from a metallocene, [{Me2SiFlu2Nd(p-BH4)2Li(THF)}2,], a co-catalyst, butyloctylmagnesium (BOMAG) and a pre-formation monomer, 1,3-butadiene, in the following contents: metallocene: 0.00007 mol / L, co-catalyst: 0.00036 mol / L. It is prepared according to a preparation method in accordance with paragraph IL 1 of patent application WO 2017093654 AL

[0129] [Tables 1] Components Cl C2 C3 C4 C5 C6 C7 EBR (la) 100.0 100.0 100.0 100.0 SBR (1b) 100.0 100.0 100.0 Black (2) 3.0 3.0 3.0 3.0 3.0 3.0 3.0 Silica (3) 85.9 85.9 85.9 85.9 85.9 85.9 85.9 Liquid silane (4) 6.9 6.9 6.9 6.9 6.9 6.9 6.9 DPG (5) 1.7 1.7 1.7 1.7 1.7 1.7 1.7 Resin 72.4 72.4 Resin 1 (8) 72.4 72.4 Resin 2 (9) 72.4 72.4 Resin 3 (10) 72.4 Ozone wax (11) 2.0 2.0 2.0 2.0 2.0 2.0 2.0 6PPD (12) 2.0 2.0 2.0 2.0 2.0 2.0 2.0 SAD (13) 2.0 2.0 2.0 2.0 2.0 2.0 2.0 ZnO (14) 0.9 0.9 0.9 0.9 0.9 0.9 0.9 CBS (15) 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Sulfur (16) 1.0 1.0 1.0 1.0 1.0 1.0 1.0

[0130] 1. Elastomer has. Mooney 80 EBR with 80% mol ethylene Tg -41°C

[0131]

[0132]

[0133]

[0134] b. SBR8228 SBR 27% wt styrene, 24%mol relative to the part diene of 1,2-butadiene units, carrying a Si-OH function at the end of the chain of Tg=-48°C 1. Black ASTM N234 from CABOT Company 2. Silica 160MP from Solvay 3. Liquid silane Si69 4. Diphenylguanidine 5. MES Oil 6. Escorez 5000 series resin from Exxon Mobil (Tg = 52°C) 7. Wingtack 10 Resin 8. Regalrez 1018 Resin 9. Piccotac 1020-E Resin 10. Ozone wax C32ST (WAX7132) 11. Santoflex 6PPD from FLEXSYS company 12. Stearic acid 13. Zinc Oxide 14. Company's Cylohexyl-Benzothiazyl Sulfenamide CBS Accelerator AKROCHEM 15. Soluble sulfur The characteristics of resins, ingredients 8 to 10 are shown in Table 2. [Tables2] Resin Supplier Trade name Tg (°C) Flavor Ethyl Aliph Mn Mw IP 1 Cray Valley Wingtack 10 -28 <0.1% 3% 97% 483 595 1.23 2 Eastman REGALREZ 1018 -23 2% 0% 98% 364 460 1.26 3 Eastman Piccotac 1020-E -30 <0.1% 2% 98% 943 1632 1.76 n.3 Results: The results are shown in Table 3.

[0135] [Tables3] Cl (inventi on) C2 (inventi on) C3 (control n) C4 (control n) C5 (control n) C6 (control n) C7 (control n) Summary of elastomer and resin components EBR (la) 100.0 100.0 100.0 100.0 SBR (1b) 100.0 100.0 100.0 Resin (7) 72.4 72.4 Resin 1 (8) 72.4 72.4 Resin 2 (9) 72.4 72.4 Resin 3 (10) 72.4 Results Base 100 tan(ô) at 40°C 139 144 118 100 100 140 147 Base 100 tan(ô) at 0°C 64 76 70 100 100 41 52

[0136] The results show that the composition in accordance with the invention makes it possible, against all expectations, to significantly improve the hysteresis performance (rolling resistance) without excessively degrading the wet grip when the elastomer matrix is ​​based on an EBR (comparison of C4 compared to C1 and C2). The wet grip performance is further degraded for the compositions whose elastomer matrix is ​​based on SBR (comparison of C5 compared to C6 and C7, as well as C1 and C2 versus C4 compared to respectively C6 and C7 versus C5) for the SBR of tg = -48°C.

[0137] The results also show that when the low Tg resin does not have all of the required characteristics, particularly in terms of Mn (Resin 3), when the elastomer matrix is ​​based on an EBR, the improvement in hysteresis performance is less and the wet grip / hysteresis compromise is degraded compared to a composition comprising a low Tg resin in accordance with the invention and an elastomer matrix based on an EBR (comparison of C3 compared to C1 and C2).

Claims

Claims

1. Rubber composition based on at least - an elastomer matrix comprising predominantly a highly saturated diene elastomer, which highly saturated diene elastomer is a copolymer of ethylene and at least one 1,3-diene in which the ethylene units represent at least 50 mol% of the monomer units of the copolymer, - a reinforcing filler, - a vulcanization system and - a plasticizing system comprising a hydrocarbon resin of low Tg (glass transition temperature), optionally hydrogenated, having a Tg of between -40°C and 20°C and a number-average molar mass (Mn) of less than or equal to 800 g / mol.

2. A rubber composition according to claim 1, wherein the ethylene units represent at least 50% and at most 95% by mole of the monomer units of the highly saturated diene copolymer.

3. A rubber composition according to any preceding claim, wherein the at least 1,3-diene is 1,3-butadiene, isoprene, myrcene or famesene, preferably 1,3-butadiene.

4. A rubber composition according to any preceding claim, wherein the copolymer of ethylene and at least one 1,3-diene is a copolymer of ethylene and 1,3-butadiene.

5. A rubber composition according to any one of the preceding claims, wherein the level of the highly saturated diene elastomer in the rubber composition varies within a range of 60 to 100 phr, preferably 80 to 100 phr, very preferably 90 to 100 phr.

6. Composition according to any one of the preceding claims in which the content of hydrocarbon resin with a Tg of between -40°C and 20°C is within a range of 20 to 120 pce, preferably 40 to 110 pce.

7. Composition according to any one of the preceding claims in which the hydrocarbon resin previously mentioned as hydrocarbon resin with a Tg of between -40°C and 20°C has a Tg of between -40°C and 0°C, more preferably between -40°C and -20°C.

8. A composition according to any preceding claim. wherein the hydrocarbon resin previously mentioned as hydrocarbon resin with a Tg of between -40°C and 20°C has a number-average molar mass greater than or equal to 250 g / mol and less than 600 g / mol.

9. Composition according to any one of the preceding claims in which the hydrocarbon resin previously mentioned as hydrocarbon resin with a Tg of between -40°C and 20°C has a polydispersity index value (PI = Mw / Mn) of at most 1.60, preferably at most 1.

40.

10. Composition according to any one of the preceding claims in which the hydrocarbon resin previously mentioned as hydrocarbon resin with a Tg of between -40°C and 20°C has an aliphatic proton level measured by NMR (standard method) of at least 90%, preferably at least 95%.

11. Composition according to any one of the preceding claims in which the hydrocarbon resin previously mentioned as hydrocarbon resin with a Tg of between -40°C and 20°C has an aromatic proton level of less than 5%.

12. Composition according to any one of the preceding claims in which the hydrocarbon resin with a Tg of between -40°C and 20°C is a predominantly styrenic and hydrogenated resin.

13. Composition according to any one of the preceding claims in which the reinforcing filler comprises a silica as the majority reinforcing filler.

14. Composition according to any one of the preceding claims in which the silica content is within a range from 50 to 160 pce.

15. A pneumatic or non-pneumatic tire comprising a composition according to any one of the preceding claims.