Elastomeric composition comprising pyrolytic carbon black

Abstract

The invention relates to an elastomer composition based on:-at least one diene elastomer comprising at least one Si-OR function at the end of the chain or in the middle of the chain, where R is a substituted or unsubstituted alkyl group or a hydrogen atom; -a reinforcing filler comprising at least one pyrolytic carbon black; and-a crosslinking system.

Description

Field of the Invention

[0001] The present invention relates to the field of reinforced elastomeric compositions, which are particularly intended for the manufacture of rubber articles, such as, in particular, semi-finished products for pneumatic or non-pneumatic tires (especially for vehicles carrying heavy loads). Background Art

[0002] Ideally, the elastomeric composition constituting the tread of a pneumatic or non-pneumatic tire must meet many technical requirements that are often conflicting, including high abrasion resistance while conferring low rolling resistance to the tire.

[0003] To increase the stiffness of the elastomeric composition, it is known, for example, to increase the content of reinforcing fillers. However, the drawback of this solution is that it increases the hysteresis of the elastomeric composition.

[0004] Furthermore, in recent years, limiting the environmental impact of tire manufacturing and use has become a major challenge for manufacturers in the industry.

[0005] Research and development initiatives for producing tires based on recycled materials have increased in number. For example, it has been proposed to use pyrolytic carbon black to completely or partially replace the conventional tire-grade carbon black used as a reinforcing filler in the elastomeric composition constituting the tire (especially the tread). While this solution provides gains in terms of hysteresis (rolling resistance), these gains come at the expense of a reduction in stiffness, which is reflected in a decrease in the abrasion resistance of the tire.

[0006] The loss of stiffness observed due to the use of pyrolytic carbon black can be compensated for, in particular, by increasing the content of reinforcing fillers in the elastomeric composition. However, this increase in the content of reinforcing fillers leads to an increase in the hysteresis of the composition, thus risking having an adverse effect on the rolling resistance performance, especially of pneumatic or non-pneumatic tires.

[0007] Therefore, there is still a need to provide elastomeric compositions that reduce the environmental footprint by incorporating recycled materials and that meet the stiffness / hysteresis compromise while maintaining other properties, and these compositions can be very particularly used to form all or part of the tread of pneumatic or non-pneumatic tires. Summary of the Invention

[0008] The present invention relates to an elastomeric composition based on:

[0009] - at least one diene elastomer comprising at least one Si-OR functional group at the end or in the middle of the chain, where R is a substituted or unsubstituted alkyl group or a hydrogen atom;

[0010] - a reinforcing filler comprising at least one pyrolytic carbon black; and

[0011] - Cross-linking system.

[0012] The present invention also relates to a rubber article comprising at least one of the elastomeric compositions, preferably selected from the group consisting of hoses, pipes, gaskets, O-rings, drive belts, engine mounts, cable insulation, shoe soles, semi-finished products for pneumatic tires, semi-finished products for non-pneumatic tires, non-pneumatic tires and pneumatic tires.

[0013] Other aspects of the invention are described below and in the claims.

[0014] definition

[0015] The expression "composition based on" is understood to mean that the composition comprises a mixture and / or in situ reaction products of the various components used, some of which may have at least partially reacted with one another and / or are intended to have reacted with one another at least partially during the various stages of manufacturing the composition; the composition may therefore be in a completely or partially crosslinked state, or in a non-crosslinked state.

[0016] The expression “parts by weight per hundred parts by weight of elastomer” (or phr) is understood to mean parts by weight per hundred parts by weight of elastomer or rubber (the two terms being synonyms).

[0017] Herein, all percentages (%) shown are weight percentages (%) unless expressly stated otherwise.

[0018] Furthermore, any numerical interval represented by the expression "between a and b" means a numerical range extending from greater than a to less than b (i.e., excluding the end values a and b), whereas any numerical interval represented by the expression "a to b" means a numerical range extending from a up to b (i.e., including the strict end values a and b).

[0019] The compounds mentioned in this specification may be of fossil origin or biobased. In the case of biobased compounds, they may be partially or completely derived from biomass or partially or completely derived from renewable raw materials derived from biomass. This particularly applies to polymers, plasticizers, fillers, and the like.

[0020] The term "tyre intended to equip vehicles carrying heavy loads" is generally understood to mean any tyre intended to equip heavy-duty vehicles, trucks, metros, buses, civil engineering vehicles, agricultural vehicles, aircraft and other loading and unloading vehicles.

[0021] The term "elastomeric matrix" is understood to mean all functionalized or non-functionalized elastomers present in the elastomeric composition.

[0022] Within the meaning of the present invention, the term "major" is understood to mean that the compound is major among compounds of the same type in the composition, i.e., the compound is the compound that accounts for the largest amount by weight among compounds of the same type. In other words, the weight of the compound accounts for at least 51% of the total weight of compounds of the same type in the composition. For example, in a system containing only one elastomer, the elastomer is major within the meaning of the present invention, while in a system containing two elastomers, the major elastomer accounts for more than half of the total weight of the elastomers, in other words the weight of the elastomer accounts for at least 51% of the total weight of the elastomers. In the same way, the "major" filler is the filler that accounts for the largest weight among the fillers in the composition. In other words, the weight of the filler accounts for at least 51% of the total weight of the fillers in the composition.

[0023] All values of the glass transition temperature "Tg" are measured in a known manner by DSC (differential scanning calorimetry) according to standard ASTM D3418 (2008). Detailed description

[0024] Surprisingly, the inventors have found that a specific combination of at least one diene elastomer, an enhancing filler, and a crosslinking system as described below makes it possible to obtain an elastomer composition that meets the said requirements. In particular, the elastomer composition can be used for pneumatic or non-pneumatic tires (especially the tread), in particular for pneumatic or non-pneumatic tires for equipping vehicles carrying heavy loads. The proposed solution makes it possible to reduce the environmental footprint of the tires by incorporating recycled materials and to obtain a good stiffness / hysteresis (abrasion resistance / rolling resistance) compromise.

[0025] Thus, the present invention relates to an elastomer composition based on:

[0026] - at least one diene elastomer comprising at least one Si-OR functional group at the end or in the middle of the chain, where R is a substituted or unsubstituted alkyl group or a hydrogen atom;

[0027] - an enhancing filler comprising at least one pyrolytic carbon black; and

[0028] - a crosslinking system.

[0029] Diene elastomer

[0030] The elastomer composition used in the context of the present invention comprises at least one diene elastomer (i.e., one or more diene elastomers) comprising at least one Si-OR functional group at the end or in the middle of the chain, where R is a hydrogen atom or a substituted or unsubstituted alkyl group, preferably C1-C 10An alkyl group, in fact even a C1-C8 or C1-C4 alkyl group, more preferably a methyl or ethyl group; the diene elastomer may additionally contain at least one functional group different from the Si-OR functional group, and the different functional group contains a heteroatom selected from N, S, O, and P.

[0031] A diene elastomer containing at least one Si-OR functional group (wherein R is a substituted or unsubstituted alkyl group or a hydrogen atom) at the end or in the middle of the chain and which may additionally contain at least one functional group different from the Si-OR functional group (the different functional group contains a heteroatom selected from N, S, O, and P) will subsequently be denoted as a "functionalized diene elastomer". The bonding of the Si-OR functional group to the elastomer chain is usually accomplished by a silicon atom.

[0032] In other words, the diene elastomer contains at least one silicon atom substituted by at least one -OR group at the end or in the middle of the chain, where R is as described above.

[0033] A functional group different from the Si-OR functional group and containing a heteroatom selected from N, S, O, and P will subsequently be denoted as an "other functional group" or "other functional group containing a heteroatom selected from N, S, O, and P" or "other different functional group".

[0034] The position "in the middle of the chain" is understood in contrast to the position "at the end of the chain". The position "in the middle of the chain" does not mean that the functional group is precisely located in the middle of the main elastomer chain. When the Si-OR functional group is in the middle of the chain, the silicon atom usually joins two branches of the main chain of the diene elastomer.

[0035] The "diene" elastomer (or rubber indifferently), whether natural or synthetic, should be understood in a known manner to mean an elastomer consisting at least in part (i.e., a homopolymer or copolymer) of diene monomer units (monomers with two conjugated or non-conjugated carbon-carbon double bonds).

[0036] These diene elastomers can be divided into two categories: "substantially unsaturated" or "substantially saturated". The term "substantially unsaturated" is generally understood to mean a diene elastomer obtained at least in part from conjugated diene monomers and having a diene source (conjugated diene) unit content of greater than 15% (mol%); thus, for example, diene elastomers of butyl rubber or EPDM-type copolymers of diene and α-olefin do not fall within the aforementioned definition but can be specifically described as "substantially saturated" diene elastomers (low or very low diene source unit content, always less than 15%).

[0037] The term "diene elastomer capable of being used in the elastomer composition according to the present invention" is specifically understood to mean:

[0038] (a) Any homopolymer of a conjugated or non-conjugated diene monomer having 4 to 18 carbon atoms;

[0039] (b) Any copolymer of a conjugated or non-conjugated diene having 4 to 18 carbon atoms and at least one other monomer.

[0040] The other monomer may be ethylene, an olefin, or a conjugated or non-conjugated diene.

[0041] Suitable as the conjugated diene is a conjugated diene having 4 to 12 carbon atoms, especially a 1,3-diene, such as in particular 1,3-butadiene and isoprene.

[0042] Suitable as the olefin are vinyl aromatic compounds having 8 to 20 carbon atoms and aliphatic α-monoolefins having 3 to 12 carbon atoms. Suitable as the vinyl aromatic compounds are, for example, styrene, o-methylstyrene, m-methylstyrene or p-methylstyrene, the commercial mixture "vinyltoluene" or p-(tert-butyl)styrene. Particularly suitable as the aliphatic α-monoolefin are acyclic aliphatic α-monoolefins having 3 to 18 carbon atoms.

[0043] Preferably, the diene elastomer is selected from polybutadiene (BR), synthetic polyisoprene (IR), butadiene copolymers, isoprene copolymers, and mixtures of these elastomers.

[0044] The functionalized diene elastomer is preferably a butadiene copolymer, more preferably a copolymer based on styrene and butadiene.

[0045] The term "copolymer based on styrene and butadiene" is understood herein to mean a copolymer produced by the polymerization of at least one styrene monomer and at least one butadiene monomer (and of course also any mixtures of such copolymers).

[0046] Particularly suitable as the styrene monomer are styrene, methylstyrene, p-(tert-butyl)styrene, methoxystyrene and chlorostyrene. Particularly suitable as the butadiene monomer are 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-bis(C1-C5 alkyl)-1,3-butadiene (such as 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) and aryl-1,3-butadiene.

[0047] Preferably, the copolymer based on styrene and butadiene is formed from styrene monomer and butadiene monomer, i.e., the sum of the molar percentages of the styrene monomer and the butadiene monomer is equal to 100%. In other words, the functionalized diene elastomer is even more preferably a copolymer of styrene and butadiene (SBR).

[0048] In some embodiments, the functionalized diene elastomer comprises at least one other functional group, said other functional group comprising at least one heteroatom selected from N, S, O, and P, and said other functional group being different from the Si-OR functional group.

[0049] In embodiments where the functionalized diene elastomer comprises at least one other functional group (a functional group different from the Si-OR functional group), the other functional group is preferably carried directly by the silicon atom of the Si-OR functional group or through a spacer group. The spacer group is defined as an atom or a saturated or unsaturated cyclic or acyclic, linear or branched divalent aliphatic C1-C 18 hydrocarbyl group (preferably a C1-C 12 hydrocarbyl group, more preferably a C1-C6 hydrocarbyl group) or a divalent aromatic C6-C 18 hydrocarbyl group. The hydrocarbyl group may optionally be substituted. Preferably, the spacer group is a saturated or unsaturated, linear or branched divalent aliphatic C1-C 18 hydrocarbyl group, preferably a C1-C 12 hydrocarbyl group, more preferably a C1-C6 hydrocarbyl group, still more preferably a C2 or C3 hydrocarbyl group.

[0050] As examples of functional groups containing at least one heteroatom selected from N, S, O, and P, mention may be made of primary amines, secondary amines, tertiary amines, cyclic amines, isocyanates, imines, cyanide compounds, thiols, carboxylates, epoxides, primary phosphines, secondary phosphines, and tertiary phosphines.

[0051] Thus, as amine functional groups, mention may be made of amines substituted by C1-C 10 alkyl groups, preferably C1-C4 alkyl groups, more preferably methyl or ethyl groups, or cyclic amines forming a heterocycle containing a nitrogen atom and at least one carbon atom (preferably 2 to 6 carbon atoms). For example, suitable are the groups methylamino-, dimethylamino-, ethylamino-, diethylamino-, propylamino-, dipropylamino-, butylamino-, dibutylamino-, pentylamino-, dipentylamino-, hexylamino-, dihexylamino-, or hexamethyleneamino-, preferably the groups diethylamino- and dimethylamino-.

[0052] As imine functional groups, mention may be made of ketimines. For example, suitable are (1,3-dimethylbutylene)amino-, (ethylene)amino-, (1-methylpropylene)amino-, (4-N,N-dimethylaminobenzylidene)amino-, (cyclohexylene)amino-, dihydroimidazole, and imidazole groups.

[0053] Thus, as carboxylate functional groups, mention may be made of acrylates or methacrylates. Such a functional group is preferably a methacrylate.

[0054] As epoxide functional groups, mention may be made of epoxy groups or glycidyloxy groups.

[0055] As a secondary or tertiary phosphine functional group, mention may be made of phosphines substituted by C1-C 10 alkyl groups, preferably C1-C4 alkyl groups, more preferably methyl or ethyl groups, or diphenylphosphine. For example, suitable are the groups methylphosphino-, dimethylphosphino-, ethylphosphino-, diethylphosphino-, ethylmethylphosphino- and diphenylphosphino-.

[0056] More preferably, other functional groups different from the Si-OR functional group are preferably amines, more preferably primary or secondary amines, and even more preferably the groups diethylamino- or dimethylamino-.

[0057] In some embodiments, the functionalized diene elastomer comprises at least one Si-OR functional group bonded to the elastomer chain via a silicon atom and at least one other functional group different from the Si-OR functional group, said other functional group preferably being directly or via a spacer group as defined above (more preferably via a saturated or unsaturated linear or branched divalent aliphatic C1-C 18 , preferably C1-C 12 , more preferably C1-C6, still more preferably C2 or C3 hydrocarbon group) bonded to the silicon atom of the Si-OR functional group. The other different functional groups can be as defined above, more particularly amines, preferably primary or secondary amines, and very particularly the groups diethylamino- or dimethylamino-. R can be as defined above.

[0058] In some embodiments, the functionalized diene elastomer comprises at least one group comprising a Si-OR functional group, which is represented by formula (Ia):

[0059] (*—) a Si(OR) b R’ c X

[0060] (Ia)

[0061] Wherein:

[0062] -*— represents bonding to the elastomer chain;

[0063] -R’ represents a substituted or unsubstituted C1-C 10 alkyl group, in fact even a C1-C8 alkyl group, preferably a C1-C4 alkyl group, more preferably methyl or ethyl;

[0064] -R independently of one another represents a hydrogen atom or a substituted or unsubstituted C1-C 10 alkyl group, in fact even a C1-C8 alkyl group, preferably a C1-C4 alkyl group, more preferably methyl or ethyl;

[0065] -X represents other functional groups (functional groups different from the Si-OR functional group), and the other functional groups can be selected from: primary amines, secondary amines, tertiary amines, cyclic amines, isocyanates, imines, cyanide compounds, thiols, carboxylic acid esters, epoxides, primary phosphines, secondary phosphines and tertiary phosphines. The other functional groups can be bonded to the silicon atom through a spacer group as defined above, and the spacer group is preferably a linear or branched divalent aliphatic C1-C 18 , more preferably C1-C 12 , more preferably a C1-C6 group;

[0066] - The value of a is 1 or 2, the value of b is 1 or 2, the value of c is 0 or 1, provided that a + b + c = 3.

[0067] In other words, the elastomer contains at least one silicon atom substituted by at least one -OR group, where R is as described above, and the substituted silicon atom corresponds to formula (Ia).

[0068] According to an alternative form of formula (Ia), a = 2, b = 1 and c = 0.

[0069] According to an alternative form, X is an amine functional group directly bonded to the silicon atom (preferably a primary amine or a secondary amine), and the silicon atom itself is directly incorporated into the elastomer chain.

[0070] According to another alternative form, X is an amine functional group bonded to the silicon atom through a spacer group as defined above, preferably a primary amine or a secondary amine. According to a preferred alternative form, the spacer group is a saturated or unsaturated linear or branched divalent aliphatic C1-C 18 hydrocarbyl group, preferably C1-C 12 hydrocarbyl group, more preferably a C1-C6 hydrocarbyl group, still more preferably a divalent aliphatic hydrocarbyl group, and even more preferably a linear divalent C2 or C3 hydrocarbyl group.

[0071] More preferably, the other functional group represented by X in formula (Ia) can be an amine functional group as described above, preferably a primary amine or a secondary amine, and the amine functional group is bonded to the silicon atom through a linear or branched divalent aliphatic C1-C6 hydrocarbyl group, preferably a C2 or C3 hydrocarbyl group. Preferably, X is diethylamine or dimethylamine, preferably bonded to the silicon atom through a linear or branched divalent aliphatic C1-C6 hydrocarbyl group, more preferably a C2 or C3 hydrocarbyl group.

[0072] In some embodiments, the functionalized diene elastomer contains at least one group of formula (Ia), wherein:

[0073] -*— represents bonding to the elastomer chain;

[0074] - The group R' represents an unsubstituted C1-C4 alkyl group;

[0075] - R independently represents a hydrogen atom or a C1-C4 alkyl group;

[0076] -X represents a primary or secondary amine functional group, bonded to the silicon atom via a linear or branched divalent aliphatic C1-C6 hydrocarbon group;

[0077] - The value of a is 1 or 2, the value of b is 1 or 2, and the value of c is 0 or 1, provided that a + b + c = 3.

[0078] In some embodiments, the functionalized diene elastomer comprises at least one group of formula (Ia):

[0079] (*—) a Si(OR) b R’ c X

[0080] (Ia)

[0081] wherein:

[0082] - *— represents bonded to the elastomer chain;

[0083] - c equals 0;

[0084] - R is as described above;

[0085] - X is as described above;

[0086] - The value of a is 2 and the value of b is 1.

[0087] The diene elastomer functionalized in the middle of the chain is preferably a copolymer based on styrene and butadiene. Even more preferably, the diene elastomer functionalized in the middle of the chain is a copolymer of styrene and butadiene bearing a group of formula (Ia), wherein X, R’, R, a, b and c are as defined above.

[0088] The functionalized diene elastomer (more preferably a copolymer of styrene and butadiene comprising a group of formula (Ia)) comprising an Si-OR functional group (very particularly a group of formula (Ia)) in the middle of the chain is mainly obtained by functionalizing the living elastomer resulting from anionic polymerization with a compound comprising an alkoxysilyl group (which is particularly selected from trialkoxysilanes and dialkoxyalkylsilane compounds substituted by groups comprising other functional groups, said other functional groups being bonded directly or via a spacer group to the silicon atom, said functional groups and spacer groups being as defined above). It should be noted that it is known to those skilled in the art that when an elastomer is functionalized by reacting a functionalizing agent with the living elastomer resulting from the anionic polymerization stage, a mixture of functionalized entities of the elastomer is obtained, the composition of which depends on the conditions of the modification reaction and particularly on the ratio of the number of reactive sites of the functionalizing agent relative to the living elastomer chain. This mixture comprises entities functionalized at the chain ends, coupled entities, star-branched entities and / or non-functionalized entities.

[0089] According to a particularly preferred alternative form, the functionalized diene elastomer comprises, as the main entity, a diene elastomer functionalized in the middle of the chain by Si-OR functional groups (very particularly groups of formula (Ia)), said Si-OR functional groups being bonded to two branches of the diene elastomer via a silicon atom.

[0090] Even more particularly, the diene elastomer functionalized in the middle of the chain represents at least 55% by weight of the functionalized diene elastomer.

[0091] Suitable as functionalizing agents or coupling agents are trialkoxysilane and dialkoxyalkylsilane compounds substituted by groups containing other functional groups, said other functional groups being bonded directly or via a spacer group to the silicon atom, the functional groups and spacer groups being as defined above. More particularly, as functionalizing agents, mention may be made of (N,N-dialkylaminopropyl)trialkoxysilanes, (N-alkylaminopropyl)trialkoxysilanes (the secondary amine functional group of which is protected by a trialkylsilyl group) and (aminopropyl)trialkoxysilanes (the primary amine functional group of which is protected by two trialkylsilyl groups), the divalent hydrocarbon group capable of linking the amine functional group to the trialkoxysilyl group being the spacer group as described above, preferably a saturated or unsaturated linear or branched divalent aliphatic C1-C 18 hydrocarbon group, preferably C1-C 12 hydrocarbon group, more preferably a C1-C6 hydrocarbon group, even more preferably a C2 or C3 hydrocarbon group. Advantageously, the functionalizing agent is selected from (N,N-dialkylaminopropyl)trialkoxysilanes. More particularly, the functionalizing agent is (3-N,N-dimethylaminopropyl)trimethoxysilane.

[0092] The functionalized diene elastomer comprising in the middle of the chain Si-OR functional groups (very particularly groups of formula (Ia)), more preferably a copolymer of styrene and butadiene, can be prepared according to methods known to those skilled in the art (such as those described in WO2009 / 133068 or WO2017001683A1).

[0093] In some embodiments, when the functionalized diene elastomer comprises Si-OR functional groups at the ends of the chain, the functionalized diene elastomer may comprise silanol functional groups or a group represented by formula (Ib) at the ends of the chain:

[0094] –(SiR1R2-O–) m H

[0095] (Ib)

[0096] wherein:

[0097] -m represents an integer with a value ranging from 3 to 8, preferably 3;

[0098] -R1 and R2 are the same or different and represent an alkyl group having 1 to 10 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms.

[0099] The diene elastomer functionalized at the end of the chain is preferably a copolymer based on styrene and butadiene, more preferably a copolymer of styrene and butadiene.

[0100] The functionalized diene elastomer containing a silanol functional group or a group of formula (Ib) at the end of the chain can be prepared according to methods known to those skilled in the art (such as the methods described in EP 0 778 311).

[0101] More particularly, such a functionalized elastomer can be prepared according to a process comprising: after the anionic polymerization stage, functionalizing the living elastomer with a functionalizing agent of the cyclic polysiloxane type, provided that the reaction medium does not polymerize the cyclic polysiloxane.

[0102] Regarding the cyclic polysiloxanes, mention may be made of those corresponding to the following formula:

[0103]

[0104] wherein m represents an integer with a value ranging from 3 to 8, preferably 3, and R1 and R2 are the same or different and represent an alkyl group having 1 to 10 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms. Among these compounds, mention may be made of hexamethylcyclotrisiloxane.

[0105] Preferably, the elastomer composition used in the case of the present invention contains at least 50 phr of the functionalized diene elastomer as described above, more preferably at least 50 phr of the functionalized diene elastomer containing at least one group having a Si-OR functional group (represented by formula (Ia) as defined above).

[0106] More preferably, the elastomer composition used in the case of the present invention contains at least 70 phr of the functionalized diene elastomer as described above, more preferably at least 70 phr of the functionalized diene elastomer containing at least one group having a Si-OR functional group (represented by formula (Ia) as defined above).

[0107] Therefore, the functionalized elastomer can be advantageously used in blend (mixing) with one or more other diene elastomers different from the functionalized elastomer, preferably with one or more other non-functionalized diene elastomers. In the case of blending, it is understood that the sum of the different elastomers used is equal to 100 phr.

[0108] Thus, in addition to the functionalized elastomers as described above, the elastomeric composition may further comprise one or more other non-functionalized diene elastomers. The other non-functionalized elastomers may be selected from polybutadiene (BR), natural rubber (NR), synthetic isoprene (IR), butadiene copolymers different from butadiene-styrene copolymers, isoprene copolymers, and mixtures of these polymers and copolymers.

[0109] Preferably, the elastomeric composition used in the context of the present invention comprises from 50 phr to 100 phr of the functionalized diene elastomer as described above, more preferably from 50 phr to 100 phr of a functionalized diene elastomer comprising at least one group containing a Si-OR functional group (represented by formula (Ia) as defined above).

[0110] More preferably, the elastomeric composition used in the context of the present invention comprises from 70 phr to 100 phr of the functionalized diene elastomer as described above, more preferably from 70 phr to 100 phr of a functionalized diene elastomer comprising at least one group containing a Si-OR functional group (represented by formula (Ia) as defined above).

[0111] In some embodiments, the elastomeric composition used in the context of the present invention comprises only the functionalized diene elastomer as described above, more preferably only a functionalized diene elastomer comprising at least one group containing a Si-OR functional group (represented by formula (Ia) as defined above).

[0112] Reinforcing filler

[0113] The elastomeric composition used in the context of the present invention comprises a reinforcing filler, said reinforcing filler comprising at least one pyrolytic carbon black. In addition to the pyrolytic carbon black, the reinforcing filler may further comprise one or more other reinforcing fillers.

[0114] Advantageously, a specific combination of at least one pyrolytic carbon black and at least one functionalized diene elastomer as defined above (particularly an elastomer functionalized in the middle of the chain, more particularly a diene elastomer functionalized in the middle of the chain by a Si-OR functional group (very particularly a group of formula (Ia) as defined above)) enables an elastomeric composition to be obtained which has the same stiffness as the compositions of the prior art and particularly improved rolling resistance.

[0115] The term "reinforcing filler" refers to any type of filler known to be capable of reinforcing an elastomeric composition which may be used particularly for the manufacture of tires, such as organic fillers (such as virgin carbon black or pyrolytic carbon black) or inorganic fillers (such as silica or alumina).

[0116] Thus, in addition to the pyrolytic carbon black, the elastomeric composition may further comprise at least one second reinforcing filler different from the pyrolytic carbon black, which second reinforcing filler is selected from silica, alumina, and virgin carbon black.

[0117] Those skilled in the art know how to adjust the total content of the reinforcing filler, including the content of the pyrolytic carbon black, according to the intended use of the elastomeric composition.

[0118] In some embodiments, in the elastomeric composition used in the context of the present invention, the content of the reinforcing filler ranges from 25 phr to 85 phr, preferably from 35 phr to 75 phr.

[0119] Preferably, the pyrolytic carbon black accounts for more than 30% by weight, more preferably more than 50% by weight, still more preferably more than 70% by weight, and even more preferably more than 90% by weight of the total weight of the reinforcing filler.

[0120] Thus, preferably, in the elastomeric composition used in the context of the present invention, the content of the reinforcing filler ranges from 25 phr to 85 phr, and the pyrolytic carbon black accounts for more than 30% by weight, more preferably more than 50% by weight, still more preferably more than 70% by weight, and even more preferably more than 90% by weight of the total weight of the reinforcing filler.

[0121] Thus, more preferably, in the elastomeric composition used in the context of the present invention, the content of the reinforcing filler comprising at least one pyrolytic carbon black ranges from 35 phr to 75 phr, and the pyrolytic carbon black accounts for more than 30% by weight, more preferably more than 50% by weight, still more preferably more than 70% by weight, and even more preferably more than 90% by weight of the total weight of the reinforcing filler.

[0122] In some embodiments, the reinforcing filler is only the pyrolytic carbon black. In some embodiments, the elastomeric composition comprises from 25 phr to 85 phr, preferably from 35 phr to 75 phr, of the reinforcing filler, which is the pyrolytic carbon black. It should thus be understood that in this particular embodiment, the elastomeric composition comprises the pyrolytic carbon black as the sole reinforcing filler (and thus the elastomeric composition does not comprise inorganic reinforcing fillers and other organic reinforcing fillers).

[0123] The reinforcing filler may be as described below.

[0124] Pyrolytic carbon black

[0125] The elastomeric composition used in the context of the present invention comprises at least one pyrolytic carbon black as the reinforcing filler.

[0126] Within the meaning of the present invention, the term "pyrolysis carbon black" is understood to mean carbon black produced by subjecting a material comprising at least one carbon-based polymer and carbon black (hereinafter the material to be pyrolyzed, for example in the case of recycling such a material) to a pyrolysis process. The physical state of the material to be pyrolyzed provided is not important, whether it is in the form of a powder, granules, strips or any other form, in a crosslinked state or an uncrosslinked state.

[0127] Preferably, the material to be pyrolyzed can be recovered from manufactured articles or products (such as by-products or waste) produced during the manufacture / production of manufactured articles; these manufactured articles can be selected from pneumatic tires, non-pneumatic tires, industrial conveyor belts, drive belts, rubber mats, rubber hoses, shoe soles and windshield wipers. Even more preferably, the pyrolysis carbon black that can be used in the context of the present invention is the carbon black obtained from a pyrolysis process in which the material to be pyrolyzed is from manufactured articles selected from pneumatic tires and non-pneumatic tires.

[0128] Pyrolysis in the context of the present invention means any type of thermal decomposition carried out under anaerobic conditions, the raw material of which is the material to be pyrolyzed as defined above. Thus, pyrolysis carbon black differs from "industrial" carbon black and / or "ASTM grade" carbon black (also known as virgin carbon black) in that the carbon-based raw material used for pyrolysis is a material comprising at least one carbon-based polymer and carbon black, rather than a material from petroleum fractions or from coal or from natural source oils.

[0129] The pyrolysis carbon black that can be used in the context of the present invention differs particularly from known carbon blacks such as industrial carbon black and / or ASTM grade carbon black, especially "furnace" carbon black (also hereinafter referred to as "virgin carbon black") in having a higher ash content.

[0130] Preferably, the pyrolysis carbon black that can be used in the context of the present invention has an ash content in the range of 5% to 30% by weight, more preferably in the range of 8% to 25% by weight, and even more preferably in the range of 10% to 22% by weight, relative to the total weight of the pyrolysis carbon black.

[0131] Preferably, the pyrolysis carbon black that can be used in the context of the present invention has a sulfur content greater than 2% by weight, preferably in the range of 2.5% to 5% by weight, relative to the total weight of the pyrolysis carbon black.

[0132] Preferably, the pyrolysis carbon black that can be used in the context of the present invention has a zinc content greater than or equal to 2% by weight, preferably in the range of 2.5% to 8% by weight, relative to the total weight of the pyrolysis carbon black.

[0133] Preferably, the pyrolysis carbon black that can be used in the context of the present invention has a value in 20m 2 / g to 200m 2 / g, more preferably 30m 2 / g to 90m2 The STSA specific surface area measured according to standard ASTM D 6556-2021 within the range of / g.

[0134] Preferably, the pyrolytic carbon black that can be used in the context of the present invention has a void volume measured according to standard ASTM D7854 (2018) at a pressure of 50 MPa within the range of 30 ml / 100 g to 60 ml / 100 g, more preferably 35 ml / 100 g to 55 ml / 100 g.

[0135] The ash content is determined by calcination in a platinum crucible in a muffle furnace at 825 °C according to the following protocol. Before each series of measurements, the crucible is pre-determined and weighed to a tare weight within an error of 0.1 mg, and the weight is denoted as P0. A 5 g pyrolytic carbon black sample is introduced into the crucible and accurately weighed to an error within 0.1 mg; this weight is denoted as P1. The crucible and its contents are pre-calcined using a Bunsen burner until smoke appears and the product ignites. After the product has completely burned, the crucible and its contents are introduced into the muffle furnace and heated at 825 °C for 1 hour. After 1 hour, the crucible is removed from the furnace and immediately introduced into a desiccator at ambient temperature. When the crucible and the ash have returned to ambient temperature, the crucible is weighed again to obtain the weight P2. Finally, the ash content (ash %) can be obtained using the following formula:

[0136]

[0137] After calcining the sample, the ash is then dissolved in an acidic medium, and the zinc content in the pyrolytic carbon black is determined by quantitative analysis using ICP-AES (inductively coupled plasma atomic emission spectroscopy). The ash is obtained by performing the above protocol. Approximately 100 mg of the ash (test sample) is taken and introduced into a PFA (perfluoroalkoxy alkane) tube for a HotBlock hot plate. Subsequently, 8 ml of 37% concentrated hydrochloric acid, 3 ml of 65% concentrated nitric acid, and 0.5 ml of 40% hydrofluoric acid are added.

[0138] Seal the tube with a stopper and heat at 130 °C for 2 hours. After cooling, transfer the contents to a 100 ml PTFE (polytetrafluoroethylene) volumetric flask that already contains 2 g of boric acid (to neutralize hydrofluoric acid) using ultrapure water. The solution is made up to the mark with ultrapure water. The resulting solution is diluted 100-fold by taking 1 ml into a 100 ml PFTE flask that previously contained 8 ml of 37% concentrated hydrochloric acid, 3 ml of 65% concentrated nitric acid, 0.5 ml of 40% hydrofluoric acid, and 2 g of boric acid. The diluted solution is then filtered through a 0.45 μm GHP syringe filter and then analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES). Before analyzing the diluted solution, at least 5 calibration samples with zinc concentrations of 0, 0.5 mg / l, 1 mg / l, 2 mg / l, and 5 mg / l are analyzed by ICP-AES. These calibration samples are prepared in 100 ml volumetric flasks by diluting a certified commercial solution with a zinc concentration of 1 g / l.

[0139] These volumetric flasks previously contained 8 ml of 37% concentrated hydrochloric acid, 3 ml of 65% concentrated nitric acid, 0.5 ml of 40% hydrofluoric acid, and 2 g of boric acid. The standard solution is analyzed by ICP-AES at a wavelength of λ Zn = 202.613 nm. For each calibration sample concentration (c), the signal intensity I Zn of zinc is plotted on an I Zn = f(c) graph, which corresponds to a calibration line (of the y = ax + b type). Subsequently, the sample solution of unknown concentration (the diluted solution) is measured under the same conditions as the calibration samples. With the aid of the calibration line obtained above, the measured intensity is correlated with the concentration. Since the test sample and volume were previously recorded, the concentration [c] 灰分 (in wt%) is directly obtained by software.

[0140] The zinc concentration [c] 炭黑 (in wt%) in the pyrolytic carbon black is obtained by the following equation:

[0141] [c] 炭黑 = [c] 灰分 * 100 * ash%.

[0142] The determination of sulfur content in pyrolytic carbon black is carried out by a LECO furnace. The LECO sulfur analyzer is designed to specifically measure the sulfur content in organic and / or inorganic materials by combustion and non-dispersive infrared detection. Before measuring the sulfur content of the sample, the boat is cleaned and the furnace is calibrated. The boat for the LECO furnace has been previously cleaned: it is important to analyze the empty boat under the same conditions as the sample. The calibration curve is prepared starting from a commercial reference sample called "BBOT", which has a purity greater than 99.99% and the contents of carbon (C), hydrogen (H), nitrogen (N), oxygen (O) and sulfur (S) are guaranteed. These contents are as follows: C% 72.52; H% 6.09; N% 6.51; O% 7.43 and S% 7.44. Weigh out 10 ± 3, 20 ± 3 and 40 ± 3 mg of BBOT almost precisely on the boat. Introduce the reference sample / boat assembly into a combustion furnace adjusted to 1350 °C under pure oxygen conditions. The combination of the furnace temperature and the analysis flow rate causes the sample to burn and releases sulfur and / or carbon in the form of SO2(g). After 20 seconds, oxygen begins to pass through the "lance" to accelerate the combustion of refractory materials. Sulfur and / or carbon in the form of SO2(g) are entrained by the oxygen stream until they pass through the infrared detection cell.

[0143] The software of the instrument plots a straight line that correlates the weight of the introduced reference sample with the response (area) observed on the detector. Thus, the calibration line is obtained. After thoroughly cleaning the sampling equipment, weigh out 80 ± 5 mg of pyrolytic carbon black almost precisely and introduce it into the boat for the LECO furnace. With the help of the calibration line, the area of the observed SO2 peak is correlated with the concentration. The software of the instrument then calculates the weight % of sulfur in the sample based on the weight of the sample introduced into the boat.

[0144] Pyrolytic carbon black is sold, for example, by BlackBear under the reference number "BBCT30" or by Scandinavian EnviroSystems under the reference number "P550".

[0145] Virgin carbon black

[0146] The elastomeric composition used in the context of the present invention may additionally contain carbon black other than pyrolytic carbon black, which is also called "virgin carbon black" because it is not produced from materials that already contain carbon black. Virgin carbon black is produced from materials from petroleum fractions or from coal or from natural source oils.

[0147] Suitable as virgin carbon black are all carbon blacks, especially those conventionally used in tires or their treads, in particular industrial carbon blacks, more specifically "furnace" carbon blacks.

[0148] Among the native carbon blacks, mention is made more particularly of the reinforcing native carbon blacks of the 100, 200 and 300 series, or of the carbon blacks of the 500, 600 or 700 series (ASTM D-1765-2017 grades), such as N115, N134, N234, N326, N330, N339, N347, N375, N550, N683 and N772 carbon blacks.

[0149] The native carbon black can be used in the individual state as it is commercially available, or in any other form (for example as a carrier for some of the rubber additives used). The native carbon black can for example already be incorporated into a diene elastomer, in the form of a masterbatch, in particular an isoprene elastomer (see for example applications WO97 / 36724-A2 and WO99 / 16600-A1).

[0150] Reinforcing inorganic filler

[0151] The elastomer composition used in the context of the present invention can comprise silica or alumina as reinforcing inorganic fillers (that is to say, one or more silicas or aluminas).

[0152] The term "reinforcing inorganic filler" should be understood herein to mean any inorganic filler or mineral filler (whatever its color and its origin (natural or synthetic)) which, also called "white filler", "transparent filler" or even "non-black filler" with respect to carbon black, is capable of reinforcing by itself alone the elastomer composition intended for the manufacture of tires without means other than intermediate coupling agents. In a known manner, some of the reinforcing inorganic fillers can be characterized in particular by the presence of hydroxyl (-OH) groups on their surface.

[0153] Particularly suitable as reinforcing inorganic fillers are mineral fillers of the siliceous type, preferably silica (SiO2), or mineral fillers of the aluminous type, in particular alumina (Al2O3). The silica used can be any reinforcing silica known to those skilled in the art, in particular any precipitated silica or pyrogenic silica with a BET specific surface area and a CTAB specific surface area both less than 450 m 2 / g, preferably between 30 m 2 / g and 400 m 2 / g, in particular between 60 m 2 / g and 300 m 2 / g.

[0154] Any type of precipitated silica can be used, in particular highly dispersible precipitated silica (HDS). These precipitated silicas (whether or not highly dispersible) are well known to those skilled in the art. Mention may be made, for example, of the silicas described in applications WO03 / 016215 - A1 and WO03 / 016387 - A1. Among the commercially available HDS silicas, in particular, 5000GR and 7000GR silicas from Evonik, or 1085GR, 1115MP, 1165MP, Premium 200MP and HRS1200MP silicas from Solvay. As non - HDS silicas, the following commercial silicas can be used: VN2GR and VN3GR silicas from Evonik, 175GR silica from Solvay or Hi - Sil EZ120G(-D), Hi - Sil EZ160G(-D), Hi - Sil EZ200G(-D), Hi - Sil 243LD, Hi - Sil 210 and Hi - Sil HDP 320G silicas from PPG.

[0155] The BET specific surface area of the silica is determined in a known manner by gas adsorption using the Brunauer - Emmett - Teller method described in "The Journal of the American Chemical Society" (Volume 60, page 309, February 1938), more specifically in accordance with the French standard NF ISO 9277 of December 1996 (multi - point (5 points) volume method - gas: nitrogen - degassing: 1 hour at 160 °C - relative pressure p / p0 range: 0.05 to 0.17). The CTAB specific surface area of the silica is determined in accordance with the French standard NF T 45 - 007 of November 1987 (method B).

[0156] As other examples of inorganic fillers that can be used in the elastomeric composition, mention may also be made of mineral fillers of the aluminous type, in particular alumina (Al2O3), aluminum oxides, aluminum hydroxides, aluminum silicates, titanium oxides, silicon carbides or silicon nitrides, such as all the reinforcing types described in applications WO99 / 28376-A2, WO00 / 73372-A1, WO02 / 053634-A1, WO2004 / 003067-A1, WO2004 / 056915-A2, US 6 610 261-B1 and US 6 747 087-B2. Particular mention may be made of alumina Baikalox A125 or CR125 APA-100 RDX (Condéa), Aluminoxid C (Evonik) or AKP-G015 (Sumitomo Chemicals).

[0157] The physical state of the provided reinforcing inorganic filler is not important, whether it is in the form of powder, microbeads, granules or beads or any other suitable densified form. Of course, "reinforcing inorganic filler" is also understood to mean a mixture of different reinforcing inorganic fillers (in particular silica as described above).

[0158] Those skilled in the art will understand that a reinforcing filler having another property can be used to replace the above-mentioned reinforcing inorganic filler, provided that the reinforcing filler having another property is covered with an inorganic layer (such as silica) or contains functional sites (in particular hydroxyl sites) on its surface that require the use of a coupling agent to establish a bond between the reinforcing filler and the diene elastomer.

[0159] In order to couple the reinforcing inorganic filler to the diene elastomer, at least a bifunctional coupling agent (or binder) designed to provide a satisfactory chemical and / or physical bond between the inorganic filler (on the surface of its particles) and the diene elastomer can be used in a known manner. In particular, at least a bifunctional organosilane or polyorganosiloxane is used. The term "bifunctional" is understood to mean that the compound has a first functional group capable of interacting with the inorganic filler and a second functional group capable of interacting with the diene elastomer. For example, such a bifunctional compound may contain a first functional group containing a silicon atom and a second functional group containing a sulfur atom, the first functional group being capable of interacting with the hydroxyl groups of the inorganic filler and the second functional group being capable of interacting with the diene elastomer.

[0160] Preferably, the organosilane is selected from organosilane polysulfides (symmetric or asymmetric) (e.g., bis(3-triethoxysilylpropyl)tetrasulfide abbreviated as TESPT sold by Evonik under the name Si69, or bis(3-triethoxysilylpropyl)disulfide abbreviated as TESPD sold by Evonik under the name Si75), polyorganosiloxanes, mercapto silanes, capped mercapto silanes (e.g., S-(3-(triethoxysilyl)propyl)octanethioate sold by Momentive under the name NXT Silane). More preferably, the organosilane is an organosilane polysulfide.

[0161] Examples of coupling agents can be found by those skilled in the art in the following documents: WO 02 / 083782, WO 02 / 30939, WO 02 / 31041, WO 2007 / 061550, WO 2006 / 125532, WO 2006 / 125533, WO 2006 / 125534, US 6,849,754, WO 99 / 09036, WO 2006 / 023815, WO 2007 / 098080, WO 2010 / 072685, and WO 2008 / 055986.

[0162] The content of the coupling agent preferably accounts for 0.5 wt% to 15 wt% relative to the amount of the reinforcing inorganic filler, preferably 4 wt% to 12 wt% relative to the amount of the reinforcing inorganic filler, and more preferably 6 wt% to 10 wt%. Generally, the content of the coupling agent is less than 20 phr, preferably in the range of 6 phr to 17 phr, preferably 8 phr to 15 phr. This content can be easily adjusted by those skilled in the art according to the content of the reinforcing inorganic filler used in the elastomer composition.

[0163] In addition to the coupling agent, the elastomer composition may further contain a coupling activator, a reagent for covering the inorganic filler, or more generally a processing aid, which can improve their processability in the unprocessed state in a known manner by improving the dispersion of the filler in the rubber matrix and reducing the viscosity of the composition. These processing aids are, for example, hydrolyzable silanes (e.g., alkylalkoxysilanes (especially alkyltriethoxysilanes)), polyols, polyethers (e.g., polyethylene glycol), primary amines, secondary amines or tertiary amines (e.g., trialkanolamines), hydroxylated or hydrolyzable POS (e.g., α,ω-dihydroxypolyorganosiloxanes (especially α,ω-dihydroxypolydimethylsiloxanes)).

[0164] Other organic filler

[0165] The elastomeric composition used in the context of the present invention may comprise a reinforcing organic filler of the functionalized polyethylene type, as described in applications WO2006 / 069792-A1, WO2006 / 069793-A1, WO2008 / 003434-A1 and WO2008 / 003435-A1.

[0166] Crosslinking system

[0167] The elastomeric composition used in the context of the present invention comprises a crosslinking system.

[0168] The crosslinking system can be of any type known to the person skilled in the art in the field of elastomeric compositions for tires. The crosslinking system can in particular be based on sulfur and / or peroxides and / or bismaleimides.

[0169] Preferably, the crosslinking system is based on sulfur; it is then called a vulcanization system.

[0170] Sulfur can be provided in any form, in particular in the form of molecular sulfur or sulfur donors. It is also preferred to have at least one vulcanization accelerator, and optionally, it is also preferred that various known vulcanization activators or known vulcanization retarders can be used, such as zinc oxide, stearic acid or equivalent compounds (such as stearates), salts of transition metals, guanidine derivatives (in particular diphenylguanidine).

[0171] Sulfur is used in a preferred content in the range of 0.5 phr to 12 phr, in particular 1 phr to 10 phr.

[0172] The vulcanization accelerator is used in a preferred content in the range of 0.5 phr to 10 phr, more preferably 0.5 phr to 5.0 phr.

[0173] As the accelerator, any compound capable of acting as a vulcanization accelerator for diene elastomers in the presence of sulfur can be used, in particular accelerators of the thiazole type and their derivatives, or sulfenamides, thiurams, dithiocarbamates, dithiophosphates, thioureas and xanthates. As examples of such accelerators, the following compounds can be particularly mentioned: 2-mercaptobenzothiazole disulfide (abbreviated as MBTS), N-cyclohexyl-2-benzothiazole sulfenamide (CBS), N,N-dicyclohexyl-2-benzothiazole sulfenamide (DCBS), N-(tert-butyl)-2-benzothiazole sulfenamide (TBBS), N-(tert-butyl)-2-benzothiazole sulfenimide (TBSI), tetrabenzylthiuram disulfide (TBZTD), zinc dibenzyldithiocarbamate (ZBEC) and mixtures of these compounds.

[0174] Common additives and processing aids

[0175] The elastomeric composition used in the context of the present invention may also comprise all or some of the common additives and processing aids commonly used in elastomeric compositions for tires known to those skilled in the art, such as plasticizers (such as plasticizing oils and / or plasticizing resins), non-reinforcing fillers, pigments, reagents for promoting initial adhesion (i.e., tackifiers), pro-oxidant metal salts, protective agents (such as anti-ozone waxes, chemical anti-ozone agents or antioxidants), anti-fatigue agents or reinforcing resins (such as those described in, for example, application WO 02 / 10269).

[0176] Preferably, in the elastomeric composition used in the context of the present invention, the content of the plasticizer is in the range of 0 phr to 20 phr, more preferably in the range of 0 phr to 10 phr.

[0177] Preparation of the composition

[0178] The elastomeric composition used in the context of the present invention is prepared in a suitable mixer using two successive preparation stages known to those skilled in the art:

[0179] - The first stage of thermomechanical processing or kneading ("non-production" stage), which can be carried out in a single thermomechanical stage, during which all the necessary components except the crosslinking system, in particular the functionalized diene elastomer, the reinforcing filler including pyrolytic carbon black and various other optional additives, are introduced into a suitable mixer (such as a standard closed mixer (e.g., of the "Banbury" type)). The reinforcing filler can be incorporated into the functionalized diene elastomer in one go or in several portions by thermomechanical kneading. The non-production stage is carried out at a high temperature up to a maximum temperature in the range of 110 °C to 200 °C for a period of time generally in the range of 2 minutes to 10 minutes.

[0180] - The second stage of mechanical processing ("production" stage) in an open mixer (such as a mill) after cooling the mixture obtained during the first non-production stage to a lower temperature (generally less than 120 °C, for example in the range of 40 °C to 100 °C). Then the crosslinking system is incorporated and then all the substances are mixed for a few minutes, for example 5 minutes to 15 minutes.

[0181] The final elastomeric composition thus obtained is then calendered into the form of, for example, sheets or plates for use particularly in laboratory characterization, or extruded into the form of a rubber semi-finished (or shaped) element that can be used, for example, as a tire tread, particularly for tires for heavy load vehicles (especially heavy-duty or civil engineering vehicles).

[0182] The elastomeric composition can be in an unprocessed state (before crosslinking or vulcanization) or in a cured state (after crosslinking or vulcanization) and can be a semi-finished product for use in tires.

[0183] The crosslinking of the elastomeric composition can be carried out in a manner known to those skilled in the art, for example, at a temperature in the range of 130 °C to 200 °C, preferably under pressure, for a sufficient time, which can vary, for example, from 5 minutes to 90 minutes.

[0184] Rubber product

[0185] Another subject of the present invention relates to a rubber article comprising at least one elastomeric composition as defined above.

[0186] The rubber article can be any type of article, such as a hose, a tube, a gasket, an O-ring, a conveyor belt, an engine mount, a cable insulator, a sole, a semi-finished product for a pneumatic tire, a semi-finished product for a non-pneumatic tire, a pneumatic tire or a non-pneumatic tire.

[0187] Preferably, the rubber article is selected from semi-finished products for pneumatic tires, semi-finished products for non-pneumatic tires, pneumatic tires and non-pneumatic tires.

[0188] A semi-finished product for a pneumatic tire or a non-pneumatic tire is a rubber product intended for the manufacture of a pneumatic tire or a non-pneumatic tire. This can be any type of rubber strip, such as, in particular, a tread, a base layer, etc.

[0189] More preferably, the elastomeric composition as defined above used in the context of the present invention constitutes all or part of the semi-finished product.

[0190] Preferably, the semi-finished product for a pneumatic tire or a non-pneumatic tire is a tread.

[0191] In a known manner, the tread of a pneumatic tire or a non-pneumatic tire includes a rolling surface intended to come into contact with the ground when the pneumatic tire or the non-pneumatic tire rolls. The tread is provided with a tread pattern, which particularly includes tread pattern elements or basic blocks delimited by various grooves.

[0192] Advantageously, the elastomeric composition as defined above used in the context of the present invention is present in the tread of a pneumatic tire or a non-pneumatic tire, preferably in the radially outer part of the tread intended to come into contact with the ground when the pneumatic tire or the non-pneumatic tire rolls. Even more preferably, the elastomeric composition as defined above used in the context of the present invention constitutes all or part of the tread (in particular the tread of a pneumatic tire or a non-pneumatic tire).

[0193] The term "pneumatic tire" is understood to mean a tire intended to cooperate with a support element (such as a rim) to form a cavity that can be pressurized to a pressure greater than atmospheric pressure.

[0194] In contrast, a "non-pneumatic tire" is a tire that supports the vehicle load by means other than pressurized inflation gas. Thus, a non-pneumatic tire is a toroidal body composed of at least one polymeric material, designed to provide the functions of a tire without bearing inflation pressure. A non-pneumatic tire can be solid or hollow. A hollow non-pneumatic tire may contain air but the air is at atmospheric pressure, i.e., it does not have the inflation stiffness contributed by inflation gas at a pressure greater than atmospheric pressure. For example, non-pneumatic tires are described in documents WO 03 / 018332 and FR2898077.

[0195] Pneumatic tires or non-pneumatic tires are intended to be fitted in particular to all types of vehicles.

[0196] Preferably, the rubber article according to the present invention is a semi-finished product for a pneumatic tire, preferably a tread, such as a tread composed in particular entirely or partially of at least one elastomeric composition as defined above. Even more preferably, the above semi-finished product is a semi-finished product for industrial vehicles such as heavy-duty vehicles, trucks, agricultural vehicles, buses, subways, civil engineering vehicles, airplanes and other handling vehicles.

[0197] Even more preferably, the rubber article according to the present invention is a pneumatic tire that particularly contains at least one elastomeric composition in the tread, and the elastomeric composition constitutes all or part of the tread. Even more preferably, the rubber article is a pneumatic tire for industrial vehicles such as heavy-duty vehicles, trucks, agricultural vehicles, buses, subways, civil engineering vehicles, airplanes and other handling vehicles. Pneumatic tires can be manufactured by any method known to those skilled in the art.

[0198] Preferably, the rubber article is a pneumatic tire or a non-pneumatic tire, the tread of which is entirely or partially composed of at least one elastomeric composition according to the present invention.

[0199] The following examples are given by way of illustration and should not be construed as limiting the present invention in any way.

[0200] Examples

[0201] Measurement methods

[0202] 1.1 Analysis of functional groups of elastomers

[0203] NMR analysis was carried out on a Bruker 500 MHz spectrometer equipped with a 5 mm BBIz "broadband" probe. For quantitative 1 1H NMR experiments, the sequence used a 30° pulse and a repetition time of 2 seconds. The sample was dissolved in carbon disulfide (CS2). 100 μl of deuterated cyclohexane (d 12 -CH) was added for locking the signal. 11H NMR spectroscopy enables quantification of the (CH3)2Si functional group by integrating the characteristic signal of the SiCH3 protons near δ = 0 ppm.

[0204] 2 D 1 H- 29 29Si NMR spectroscopy enables determination of the nature of the functional groups by virtue of the chemical shift values of the silicon nuclei and protons (through two bonds) near 2 J.

[0205] 1.2 Analysis of the microstructure of the elastomer

[0206] Near-infrared (NIR) spectroscopy is used to quantitatively determine the weight content of styrene in the elastomer and its microstructure (relative distribution of 1,2-vinyl-, trans-1,4- and cis-1,4-butadiene units). The principle of this method is based on the Beer-Lambert law, which is applicable to multicomponent systems.

[0207] Since this method is indirect, it involves using standard elastomers of a certain composition determined by 13 13C NMR for multivariate calibration [Vilmin, F., Dussap, C. and Coste, N., Applied Spectroscopy, 2006, 60, 619-29]. The styrene content and microstructure are then calculated from the NIR spectra of elastomer films with a thickness of approximately 730 μm. Using a Bruker Tensor 37 Fourier transform near-infrared spectrometer equipped with an InGaAs detector cooled by the Peltier effect, spectra are acquired in transmission mode with a resolution of 2 cm -1 −1 between 4000 cm -1 −1 and 6200 cm -1 −1.

[0208] 1.3 Kinetic properties

[0209] Kinetic properties are measured on a viscosity analyzer (Metravib VA4000) according to standard ASTM D 5992-96. The response of a sample of a vulcanized elastomer composition (a cylindrical test specimen with a thickness of 4 mm and a cross-section of 400 mm 2 2) subjected to a simple alternating sinusoidal shear stress at a frequency of 10 Hz at a temperature of 60 °C is recorded.

[0210] For the measurement of the complex dynamic shear modulus (G*) and the loss factor tan(δ), a strain amplitude sweep is performed from 0.1% to 100% peak-to-peak (outward cycle), then from 100% to 0.1% peak-to-peak (return cycle). For the return cycle, the maximum value of the observed tan(δ) at 60 °C (denoted as tan(δ) max ) and the modulus G at 25% strain * (denoted as G*25%) are shown.

[0211] The value of tan(δ) max represents the hysteresis of the material, which represents the rolling resistance in this case: the smaller the value of tan(δ) max , the better the rolling resistance. The value of G*25% measured at 60 °C represents the stiffness, i.e., the resistance to deformation: the higher the value of G*25% at 60 °C, the greater the stiffness of the material, and thus the better the wear resistance.

[0212] All values are expressed as a base 100 relative to a given control.

[0213] 1.4 Tensile testing

[0214] Tensile testing makes it possible to determine the elastic stress and fracture properties. Unless otherwise stated, the tensile testing is carried out according to French standard NF T 46-002 (1988).

[0215] Processing the tensile records makes it possible to particularly plot the curve of the modulus as a function of elongation. The modulus used herein is the nominal (or apparent) secant modulus, which is measured during the first elongation and calculated by reducing to the initial cross-section of the test specimen. The nominal secant modulus (or apparent stress, in MPa) at 300% elongation (denoted as MSA300) is measured during the first elongation.

[0216] All values are expressed as a base 100 relative to a given control. Values greater than 100 indicate values greater than the control.

[0217] Preparation of the composition:

[0218] The preparation of the elastomeric composition is carried out as follows.

[0219] A functionalized diene elastomer or a non-functionalized diene elastomer is introduced into a closed mixer, filled to 70%, and the initial vessel temperature of the mixer is about 100 °C. Subsequently, for each elastomer composition, the reinforcing filler to be tested is introduced, and then, after kneading for one to two minutes, various other components except the vulcanization system are introduced. Then, thermomechanical processing (non-production stage) is carried out in one stage, which lasts for a total of about 3 minutes to 5 minutes until the maximum "drop" temperature of 160 °C is reached. The mixture thus obtained is recovered and cooled, and then the vulcanization system (sulfur and a sulfenamide-type accelerator) is added to an open mixer (finishing mill) at 30 °C, and the mixture is combined (production stage) for about 5 minutes to 6 minutes.

[0220] Subsequently, the elastomer compositions thus obtained are calendered into sheets (with a thickness of 2 mm to 3 mm) for measuring their physical or mechanical properties.

[0221] Table 1 describes the formulations of the prepared elastomer compositions (components and contents - unless otherwise stated, the contents are expressed in phr).

[0222] The rubber properties of these compositions are measured after curing at 150 °C for 30 minutes. The results obtained are listed in Table 1.

[0223] Table 1: Formulations of different compositions and properties in the cured state

[0224]

[0225] (1) Diene elastomer: solution SBR, non-extended, non-functionalized, having 24 wt% of 1,2-polybutadiene units relative to the butadiene moiety; having 26.5 wt% of styrene units relative to the total weight of the copolymer, Tg = -48 °C;

[0226] (2) Diene elastomer: solution SBR, non-extended, functionalized with an amino-alkoxysilane functional group in the middle of the chain, having 24% wt of 1,2-polybutadiene units relative to the butadiene moiety; having 26.5 wt% of styrene units relative to the total weight of the elastomer, Tg = -48 °C; this copolymer is synthesized according to the method described in document WO2009 / 133068;

[0227] (3) Conventional carbon black of grade N326 compliant with ASTM D-1765-2017 sold by Cabot, having an ash content of less than 0.7 wt% relative to the total weight of the carbon black, having a sulfur content of less than 1.2 wt% relative to the total weight of the carbon black, and zinc in the impurity state (in the ppm order of magnitude);

[0228] (4) Pyrolytic carbon black P550 from Scandinavian Enviro Systems, having an ash content equal to 18.5% by weight relative to the total weight of the pyrolytic carbon black, a sulfur content equal to 3% by weight relative to the total weight of the pyrolytic carbon black, and a zinc content equal to 4.5% by weight relative to the total weight of the pyrolytic carbon black;

[0229] (5) 2,2,2 - trimethyl - 1,2 - dihydroquinoline from Flexsys;

[0230] (6) N-(1,3 - dimethylbutyl)-N'-phenyl - p - phenylenediamine from Flexsys;

[0231] (7) N - cyclohexyl - 2 - benzothiazole sulfenamide from Flexsys.

[0232] Tests have shown that, compared with elastomeric compositions (C1, C2, C3 and C4) not in accordance with the present invention, the elastomeric compositions (A1 and A2) in accordance with the present invention have an improvement in the compromise between stiffness / hysteresis / reinforcement.

[0233] As observed from Table 1, in order to obtain an equivalent stiffness (value of G*25% at 60 °C) to that of the control elastomeric composition (C1), an increase in the content of pyrolytic carbon black in the elastomeric composition of non - functionalized elastomers within the meaning of the present invention (C3 relative to C2) is accompanied by an increase in hysteresis (tan(δ)max at 60 °C), thus by a decrease in rolling resistance performance, and also by a decrease in reinforcement (MSA300).

[0234] Surprisingly, compared with the elastomeric composition C3 not in accordance with the present invention, the elastomeric composition A2 in accordance with the present invention and containing a functionalized diene elastomer within the meaning of the present invention enables a better stiffness / hysteresis compromise to be obtained at equivalent stiffness.

Claims

1. An elastomeric composition, the elastomeric composition being based on: - at least one diene elastomer, the diene elastomer containing at least one Si-OR functional group at the end or in the middle of the chain, where R is a substituted or unsubstituted alkyl group or a hydrogen atom; - a reinforcing filler, the reinforcing filler including at least one pyrolytic carbon black; and - a crosslinking system.

2. The elastomeric composition according to claim 1, wherein, The Si-OR functional group is located in the middle of the diene elastomer chain.

3. The elastomeric composition according to claim 1 or 2, wherein The diene elastomer further contains at least one other functional group different from the Si-OR functional group, the different functional group containing a heteroatom selected from N, S, O or P; preferably, the functional group is carried directly by the silicon atom of the Si-OR functional group or through a spacer group.

4. The elastomeric composition according to any one of claims 1 to 3, wherein, The diene elastomer contains a group containing a Si-OR functional group in the middle of the chain, and this group is represented by formula (Ia): (*—) a Si(OR) b R’ c X (Ia) Where: - *— represents bonding to the elastomer chain; -R’ represents a substituted or unsubstituted C1-C 10 alkyl group, in fact even a C1-C8 alkyl group, preferably a C1-C4 alkyl group; -R each independently represents a hydrogen atom or a substituted or unsubstituted C1-C 10 alkyl group, in fact even a C1-C8 alkyl group, preferably a C1-C4 alkyl group; - X represents another functional group, which is a functional group different from the Si-OR functional group, and the other functional group can be selected from: primary amine, secondary amine, tertiary amine, cyclic amine, isocyanate, imine, cyanide compound, thiol, carboxylic acid ester, epoxide, primary phosphine, secondary phosphine and tertiary phosphine, and X is bonded to the silicon atom directly or through a spacer group; - The value of a is 1 or 2, the value of b is 1 or 2, the value of c is 0 or 1, provided that a + b + c = 3.

5. The elastomeric composition according to claim 4, wherein, In formula (Ia): - *— represents bonding to the elastomer chain; - R’ represents an unsubstituted C1-C4 alkyl group; - R independently represents a hydrogen atom or a C1-C4 alkyl group; - X represents a primary amine functional group or a secondary amine functional group bonded to the silicon atom directly or through a spacer group; - The value of a is 1 or 2, the value of b is 1 or 2, the value of c is 0 or 1, provided that a + b + c = 3.

6. The elastomeric composition according to claim 4 or 5, wherein The spacer group is an atom or a saturated or unsaturated cyclic or acyclic linear or branched divalent aliphatic C1-C 18 hydrocarbon group or a divalent aromatic C6-C 18 hydrocarbon group, and the divalent aliphatic C1-C 18 hydrocarbon group is preferably a C1-C 12 hydrocarbon group, more preferably a C1-C6 hydrocarbon group.

7. The elastomeric composition according to any one of the preceding claims, wherein, The diene elastomer is a copolymer based on butadiene and styrene, more preferably a copolymer of styrene and butadiene.

8. The elastomeric composition according to any one of the preceding claims, wherein, Relative to the total weight of the pyrolytic carbon black, the pyrolytic carbon black has an ash content in the range of 5 wt% to 30 wt%, preferably 8 wt% to 25 wt%.

9. The elastomeric composition according to any one of the preceding claims, wherein, Relative to the total weight of the pyrolytic carbon black, the pyrolytic carbon black has a sulfur content greater than 2 wt%, preferably in the range of 2.5 wt% to 5 wt%.

10. The elastomeric composition according to any one of the preceding claims, wherein, The composition contains 25 phr to 85 phr, preferably 35 phr to 75 phr of the reinforcing filler.

11. The elastomeric composition according to any one of the preceding claims, wherein, The pyrolytic carbon black accounts for more than 30 wt% of the total weight of the reinforcing filler, more preferably more than 50 wt%, still more preferably more than 70 wt%, still more preferably more than 90 wt%.

12. The elastomeric composition according to any one of the preceding claims, wherein, The reinforcing filler further includes at least one second reinforcing filler different from the pyrolytic carbon black, and this second reinforcing filler is selected from virgin carbon black, alumina and silica.

13. A rubber product, which contains at least one elastomeric composition according to any one of claims 1 to 12, and the product is preferably selected from hoses, tubes, gaskets, O-rings, conveyor belts, engine mounts, cable insulators, shoe soles, semi-finished products for pneumatic tires, semi-finished products for non-pneumatic tires, non-pneumatic tires and pneumatic tires.

14. The rubber product according to claim 13, characterized in that, The rubber product is a semi-finished product for pneumatic tires, preferably a tread.

15. The rubber article according to claim 13, wherein the article is a pneumatic tire or a non-pneumatic tire, and all or part of its tread is composed of at least one elastomeric composition according to any one of claims 1 to 12.

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