Functionalized styrene-butadiene random copolymers and process for the preparation thereof

Abstract

Functionalized styrene-butadiene random copolymer having the following characteristics: (i) a glass transition temperature (Tg) comprised between -80°C and -55°C, preferably comprised between -75°C and -60°C; (ii) a content of styrene units comprised between 5% by weight and 25% by weight, preferably comprised between 10% by weight and 20% by weight, more preferably comprised between 13% by weight and 17% by weight, with respect to the total weight of the copolymer; (iii) a content of 1,2-vinyl units comprised between 15% by weight and 50% by weight, preferably comprised between 20% by weight and 40% by weight, more preferably comprised between 30% by weight and 36% by weight, with respect to the total weight of the butadiene units; (iv) a peak average molecular weight (Mp) comprised between 100 kDa and 250 kDa, preferably comprised between 150 kDa and 195 kDa; (v) a polydispersion index (PDI), that is, the ratio between the weight average molecular weight (Mw) and the number average molecular weight (Mn) (Mw / Mn), less than or equal to 1.5, preferably comprised between 1.1 and 1.45; (vi) a Mooney viscosity (ML1+4@100°C) comprised between 40 and 120, preferably comprised between 50 and 90, more preferably comprised between 55 and 75; (vii) polystyrene blocks wherein the polymer chains consisting of a chain of at least 16 consecutive styrene units are present in an amount less than or equal to 5% by weight, preferably less than 3% by weight, more preferably less than 1% by weight, with respect to the total weight of the styrene units present in the copolymer. The aforesaid functionalized styrene-butadiene random copolymer is advantageously usable in elastomeric compositions, in particular in silica-based elastomeric compositions, which in turn can be used for the production of tires, in particular tire treads, having a good rolling resistance, thereby allowing lower energy consumption (i.e. lower fuel consumption). More in particular, said functionalized styrene-butadiene random copolymer is advantageously usable in elastomeric compositions that can in turn be used for the production of winter and all-season tires that must guarantee excellent performance under "extreme" conditions such as wet, snow and ice.

Description

[0001] FUNCTIONALIZED STYRENE-BUTADIENE RANDOM COPOLYMERS AND PROCESS FOR THE PREPARATION THEREOF

[0002] DESCRIPTION

[0003] The present invention relates to functionalized styrene-butadiene random copolymers.

[0004] More in particular, the present invention relates to a functionalized styrene- butadiene random copolymer having the specific characteristics below reported, in particular a low glass transition temperature (Tg) (i.e. a Tgless than or equal to -55°C) and a high degree of randomization of the styrene units.

[0005] The aforesaid functionalized styrene-butadiene random copolymer is advantageously usable in elastomeric compositions, in particular in silica-based elastomeric compositions, which in turn can be used for the production of tires, in particular tire treads, having a good rolling resistance, thereby allowing lower energy consumption (i.e. lower fuel consumption). More in particular, said functionalized styrene-butadiene random copolymer is advantageously usable in elastomeric compositions that can in turn be used for the production of winter and all-season tires that must guarantee excellent performance under “extreme” conditions such as wet, snow and ice.

[0006] The present invention also relates to a process for the preparation of said functionalized styrene-butadiene random copolymer.

[0007] The present invention also relates to elastomeric compositions, in particular silica- based elastomeric compositions, which in turn can be used for the production of tires, in particular tire treads, comprising said functionalized styrene-butadiene random copolymer.

[0008] For some years now, the demand from tire manufacturers for functionalized styrene-butadiene copolymers having a low glass transition temperature (Tg) (i.e. a Tgless than or equal to -60°C) is progressively increasing as a consequence of the more and more marked development of certain products such as, for example, winter tires and all- season tires and the more and more frequent implementation of elastomeric compositions for tires that provide for the total or partial replacement of High Cis Butadiene Rubbers (HCBRs) having a glass transition temperature (Tg) < -90°C.

[0009] With a view to energy efficiency, the trend is further justified by the benefits that said functionalized styrene-butadiene copolymers bring in terms of processability of the silica-based elastomeric compositions that can in turn be used in the production of tires having a good rolling resistance, thus enabling lower energy consumption (i.e. lower fuel consumption) as, for example, reported in the following patents: US 10,676,542, US 8,633,281, US 7,807,747, US 11,414,503, EP 3,502,144, EP 3,260,476, EP 3,309,180; EP 0778311.

[0010] Processes for the production of styrene-butadiene copolymers are known in the art.

[0011] For example, it is known that the glass transition temperature (Tg) of styrene- butadiene copolymers is influenced by the content of styrene and by the content of 1,2- vinyl units: a high content of styrene, as well as a high content of 1,2- vinyl units, leads to a rise in the glass transition temperature (Tg). It is also known that adjusting the content of styrene and of 1,2-vinyl units through appropriate measures such as, for example, the use of polar modifiers, the increase in the trigger temperature of the polymerization reaction, allows to obtain low glass transition temperatures (Tg) (i.e. Tgless than or equal to -60°C), but has a negative effect on the randomization of styrene: more details can be found, for example, in Hsieh E. and Quirk R.P., 'Anionic polymerisation - principles and practical applications” (1996), Marcel Dekker, Inc., New York, Chapter 3, par. 6, 7, 9 and 10.

[0012] The patent US 5,532,327, relates to a solution polymerization process for the preparation of an organic polymer from styrene and at least one polymerizable diene monomer, comprising: a) providing a liquid reaction medium adapted to carry out said polymerization, said reaction medium containing styrene and a polymerizable diene monomer; and, b) polymerizing, via anionic route, said styrene and said diene monomer, thereby forming random copolymer chains, wherein the total amount of said styrene used in said polymerization is at least 50% by weight based on the total weight of polymerizable styrene and diene monomer used in said polymerization, and wherein a randomizing agent is added to said reaction medium prior to and / or during said polymerization in an amount sufficient to allow a content of 1,2-vinyl units greater than 50%. Said organic polymer has a glass transition temperature of less than 60°C, preferably comprised between 25 °C and 60°C.

[0013] It is therefore easy to understand how the use of a randomizing agent does not always make it possible to obtain styrene-butadiene copolymers having low glass transition temperatures (Tg) (i.e. Tgless than or equal to -60°C).

[0014] Patent EP 3705502 relates to a modified conjugated diene polymer having the following characteristics i) to v): i) a glass transition temperature from -90°C to -50°C; ii) a Mooney viscosity measured in accordance with standard ASTM DI 646 from 50 to 100; iii) a content of 1,2-vinyl units less than or equal to 30% by weight with respect to the total weight of the polymer; iv) a polydispersion index (PDI), that is, the ratio between the weight average molecular weight (Mw) and the number average molecular weight (Mn) (Mw / Mn) between 1.5 and 3.5; v) a Mooney relaxation measured at 110°C less than or equal to 0.7.

[0015] The aforesaid patent also describes a process for the preparation of a modified conjugated diene polymer comprising a step of polymerising a conjugated diene monomer and, optionally a vinyl aromatic monomer, in the presence of an organometallic compound and, optionally, of a polar modifier, in a hydrocarbon solvent in order to obtain an active polymer which is coupled to an organo-metal (SI); and a step of reacting the active polymer prepared in step (SI) with a modifier (S2), wherein the polymerization reaction (SI) and the modification reaction (S2) are carried out continuously or discontinuously.

[0016] The aforesaid modified conjugated diene polymer is said to be advantageously usable in elastomeric compositions in turn usable for the production of tires having a good resistance to both rolling and abrasion.

[0017] However, no reference is made in the above-mentioned documents to functionalized styrene-butadiene copolymers having both a low glass transition temperature (Tg) (i.e. a Tgless than or equal to -55°C) and a high degree of randomization of the styrene units. The Applicant therefore set itself the problem of finding functionalized styrenebutadiene copolymers having the above-mentioned characteristics.

[0018] The Applicant has now found styrene-butadiene copolymers having a low glass transition temperature (Tg) (i.e. a Tgless than or equal to -55°C) and a high degree of randomization of the styrene units capable of being advantageously usable in elastomeric compositions, in particular in silica-based elastomeric compositions, which in turn can be used for the production of tires, in particular tire treads, having a good rolling resistance, thereby allowing lower energy consumption (i.e. lower fuel consumption). More in particular, said functionalized styrene-butadiene random copolymers are advantageously usable in elastomeric compositions that can in turn be used for the production of winter and all-season tires that must guarantee excellent performance under “extreme” conditions such as wet, snow and ice.

[0019] Therefore, the object of the present invention is a functionalized styrene-butadiene random copolymer having the following characteristics:

[0020] (i) a glass transition temperature (Tg) comprised between -80°C and -55°C, preferably comprised between -75°C and -60°C;

[0021] (ii) a content of styrene units comprised between 5% by weight and 25% by weight, preferably comprised between 10% by weight and 20% by weight, more preferably comprised between 13% by weight and 17% by weight, with respect to the total weight of the copolymer;

[0022] (iii) a content of 1,2-vinyl units comprised between 15% by weight and 50% by weight, preferably comprised between 20% by weight and 40% by weight, more preferably comprised between 30% by weight and 36% by weight, with respect to the total weight of the butadiene units;

[0023] (iv) a peak average molecular weight (Mp) comprised between 100 kDa and 250 kDa, preferably comprised between 150 kDa and 195 kDa;

[0024] (v) a polydispersion index (PDI), that is, the ratio between the weight average molecular weight (Mw) and the number average molecular weight (Mn) (Mw / Mn), less than or equal to 1.5, preferably comprised between 1.1 and 1.45;

[0025] (vi) a Mooney viscosity (MLl+4@ 100°C) comprised between 40 and 120, preferably comprised between 50 and 90, more preferably comprised between 55 and 75; (vii) polystyrene blocks wherein the polymer chains constituted by a chain of at least 16 consecutive styrene units are present in an amount less than or equal to 5% by weight, preferably less than 3% by weight, more preferably less than 1% by weight, with respect to the total weight of the styrene units present in the copolymer.

[0026] For the purpose of the present description and of the following claims, the definitions of the numeric ranges always include the extremes unless specified otherwise.

[0027] For the purpose of the present description and of the following claims, the term “comprising” also includes the terms “which essentially consists of’ or “which consists of’.

[0028] It should be noted that the specific amount of polystyrene blocks wherein the polymer chains consist of a chain of at least 16 consecutive styrene units reported above in point (vii) is evidence of the high degree of randomization of the random styrenebutadiene copolymer object of the present invention.

[0029] In accordance with a preferred embodiment of the present invention, said functionalized styrene-butadiene random copolymer has a coupling ratio comprised between 10% by weight and 70% by weight, preferably comprised between 12% by weight and 50% by weight, more preferably comprised between 15% by weight and 40% by weight, with respect to the total weight of the copolymer.

[0030] In accordance with a preferred embodiment of the present invention, said functionalized styrene-butadiene random copolymer has a terminal functionalization percentage comprised between 30% by weight and 90% by weight, preferably comprised between 50% by weight and 88% by weight, more preferably comprised between 60% by weight and 85% by weight, with respect to the total weight of the copolymer.

[0031] As mentioned above, the present invention also relates to a process for the preparation of said functionalized styrene-butadiene random copolymer.

[0032] Therefore a further object of the present invention is to provide a batch process for the preparation of a functionalized styrene-butadiene random copolymer comprising the following sequential steps: (a) copolymerizing, via anionic route, 1,3-butadiene and styrene, in the presence of at least one hydrocarbon solvent and of at least one lithium-based initiator and continuing said copolymerization for the time necessary to reach a temperature Ti defined by the following equation:

[0033] T1 = Trigger + AT wherein:

[0034] T u-igger is the temperature at which said at least one lithium-based initiator is added and the copolymerization is triggered;

[0035] AT is comprised between 5°C and 39°C, preferably comprised between 10°C and 38°C, more preferably comprised between 13°C and 35°C;

[0036] (b) adding at least one randomizing agent and continuing the copolymerization until substantially complete conversion of 1,3-butadiene and styrene;

[0037] (c) optionally, adding at least one coupling agent;

[0038] (d) adding at least one alkoxy-silane.

[0039] For the purpose of the present description and of the following claims, the phrase “substantially complete conversion” means that polymerisation is continued until at least 98%, preferably at least 99%, more preferably 99.9%, of the charged monomers, i.e. 1,3-butadiene and styrene, has been polymerised.

[0040] In accordance with a preferred embodiment of the present invention, in said step (a), said at least one hydrocarbon solvent can be selected, for example, from aliphatic, cycloaliphatic or aromatic hydrocarbon solvents such as, for example, propane, n- butane, zso-butane, 2-methyl propane, zz-pentane, 2-methyl butane, 2-methyl pentane, 3- methyl pentane, zso-pentane, zz-hexane, zz-heptane, zz-octane, cyclohexane, cyclopentane, methyl-cyclopentane, methyl-cyclohexane, 2,2-dimethyl butane, 2,3-dimethyl butane, 2,2-dimethyl pentane, 2,3,3-trimethyl butane, 3,3-dimethyl pentane, 2,3-dimethyl pentane, 2-methyl hexane, 3 -methyl hexane, benzene, toluene, xylene, ethylbenzene, or mixtures thereof. Said solvents can advantageously be used in an anhydrous form. Cyclohexane, zz-hexane, or mixtures thereof, in anhydrous form, are preferred.

[0041] Generally, the amount of hydrocarbon solvent used in said copolymerization is such as to allow complete solubility of the monomers used (i.e. 1,3-butadiene and styrene), of the additives that can be present, of the compounds obtained in the aforesaid steps (a)-(d), complete stirring of the reaction mixture, also during said copolymerization, and the diffusion of the heat of the reaction. Preferably, said hydrocarbon solvent is used in such an amount as to have a concentration of monomers (i.e. 1,3-butadiene and styrene) in the hydrocarbon solvent comprised between 4% by weight and 25% by weight, more preferably comprised between 6% by weight and 18% by weight, with respect to the total weight of the hydrocarbon solvent.

[0042] In accordance with a preferred embodiment of the present invention, said step (a) can be carried out in the presence of:

[0043] 75% by weight - 95% by weight, preferably 80% by weight - 90% by weight, more preferably 83% by weight - 87% by weight, with respect to the total weight of 1,3-butadiene and styrene, of 1,3-butadiene; and

[0044] 5% by weight - 25% by weight, preferably 10% by weight - 20% by weight, more preferably 13% by weight - 17% by weight, with respect to the total weight of 1,3-butadiene and styrene, of styrene.

[0045] In accordance with a preferred embodiment of the present invention, in said step (a), said at least one lithium-based initiator can be selected, for example, from compounds having general formula (I):

[0046] Ri-Li (I) wherein Ri represents a C1-C20, preferably C2-C12, linear or branched alkyl group, a C3- C30, preferably C4-C10 cycloalkyl group, a C6-C30, preferably C6-C12 aryl group.

[0047] In accordance with a particularly preferred embodiment of the present invention, in said step (a), said at least one lithium-based initiator can be selected, for example, from: lithium methyl, lithium ethyl, lithium n-butyl, lithium sec-butyl, lithium / -butyl, lithium n-propyl, lithium-2-propyl, lithium zso-butyl, lithium n-pentyl, lithium cyclohexyl, lithium phenyl, lithium 1-methyl-styryl, lithium p-tolyl, lithium naphthyl, L,L-diphenyl-5-lithium-3-methyl-pentyl, or mixtures thereof. Lithium n-butyl is preferred.

[0048] The amount of lithium-based initiator that can be used in the process object of the present invention depends on various factors such as, for example, the purity of the monomers that are copolymerized and the molecular weight of the copolymer to be obtained. Generally, said lithium-based initiator can be used in an amount comprised between 0.02 phm and 0.06 phm (phm = parts per hundred parts by weight of monomer(s)). Preferably, said lithium-based initiator can be used in an amount comprised between 0.03 phm and 0.05 phm.

[0049] In accordance with a preferred embodiment of the present invention, in said step

[0050] (b) said at least one randomizing agent can be selected, for example, from: non-cyclic ethers such as, for example, ethyl ether, or mixtures thereof; tertiary amines such as, for example, tri-butylamine; cyclic ethers such as, for example, tetrahydrofuran (THF); chelating ethers such as, for example, ethylene glycol dimethyl ether (dimethylglime), dioxane, 2-ethoxymethyl-tetrahydrofuran (THFA-ethyl), 2-methoxy ethyltetrahydropyran, or mixtures thereof; chelating amines such as, for example, N,N,N’,N’- tetramethylethylenediamine (TMEDA); or mixtures thereof. Tetrahydrofuran (THF), 2- (ethoxymethyl)-tetrahydrofuran (THFA-ethyl), or mixtures thereof, are preferred; 2- (ethoxymethyl)-tetrahydrofuran (THFA-ethyl) is particularly preferred.

[0051] The amount of randomizing agent that can be used in the process object of the present invention depends on various factors such as, for example, the structure of the randomizing agent used, the desired quantity of polystyrene blocks having polymer chains consisting of a chain of at least 16 consecutive styrene units, the degree of randomization of the styrene units. By way of example, 2-(ethoxymethyl)- tetrahydrofuran (THFA-ethyl) can be used in an amount comprised between 50 ppm and 1000 ppm, preferably comprised between 100 ppm and 500 ppm, with respect to the total amount of hydrocarbon solvent (ppm = parts per million).

[0052] In accordance with a preferred embodiment of the present invention, in said step

[0053] (c), said at least one coupling agent can be selected, for example, from organo-metallic compounds having general formula (II):

[0054] (R2)mM(X)p (II) wherein R2represents a Ci-C2o, preferably C2-Cs, linear or branched alkyl group, a Ci- C2o, preferably C2-Cs, linear or branched alkenyl group, a C3-C30, preferably C4-C10 cycloalkyl group, a C3-C30, preferably C4-C10 cycloalkenyl group, a C6-C30, preferably C6-Ci2aryl group, M represents a silicon, germanium or tin atom, preferably silicon or tin, X represents a halogen atom such as, for example, chlorine, bromine, fluorine, iodine, preferably chlorine, m is an integer comprised between 0 and 2, and p is an integer comprised between 2 and 4.

[0055] In accordance with a particularly preferred embodiment of the present invention, in said step (c), said coupling agent can be selected, for example, from: silicon tetrachloride (SiCU), tin tetrachloride (SnCU), or mixtures thereof. Tin tetrachloride (SnCU), is preferred. Preferably, said coupling agent and said lithium-based initiator can be used in a molar ratio comprised between 0.1 and 0.7, preferably comprised between 0.12 and 0.5, more preferably comprised between 0.15 and 0.4.

[0056] In accordance with a preferred embodiment of the present invention, in said step (d), said at least one alkoxy-silane can be selected, for example, from compounds having general formula (III) or (IV):

[0057] O-R4

[0058] R3-O— Si — (R6)— A (III)

[0059] O-R5

[0060] O-R4

[0061] R3— Si — (R6)— A (IV)

[0062] O-R5wherein:

[0063] R3, R4 and R5, each independently, represent a C1-C20, preferably C2-C12, linear or branched alkyl group, a C3-C30, preferably C4-C10 cycloalkyl group, a C6-C30, preferably C6-C12 aryl group; preferably they represent methyl, ethyl, propyl, n- butyl, sec-butyl, ter-butyl, octyl;

[0064] Re represents a C1-C20, preferably C1-C10 linear or branched hydrocarbon chain, optionally containing one or more unsaturations, said unsaturations being optionally present in an amount not exceeding 2, optionally containing heteroatoms selected from oxygen, nitrogen, sulphur, said heteroatoms being optionally present in an amount not exceeding three;

[0065] A represents a C1-C20, preferably C2-C12, linear or branched alkyl group, a C3-C12, preferably C3-C6 heterocyclic group, containing at least one heteroatom selected from nitrogen, oxygen, sulphur, silicon, selenium, phosphorus, preferably containing one nitrogen atom and one oxygen atom; preferably said heterocyclic group is linked to the Re substituent via a nitrogen atom, even more preferably said heterocyclic group is morpholine.

[0066] In accordance with a preferred embodiment of the present invention, said alkoxysilane can be selected, for example, from: tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, tetrapentoxysilane, tetrahexoxysilane, tetraheptoxysilane, tetraoctoxysilane, triethoxypropoxysilane, triethoxybutoxysilane. triethoxypentoxysilane, triethoxyhexoxysilane, triethoxyheptoxysilane. triethoxyoctoxysilane, diethoxypropoxyxysilane, diethoxydibutoxysilane. diethoxydipentoxysilane, diethoxydihexoxysilane, diethoxydieptoxysilane. diethoxydioctoxysilane, triproxyethoxysilane, tripropoxybutoxysilane. tripropoxypentoxysilane, tripropoxyhexoxysilane, tripropoxyheptoxysilane. tripropoxyoctoxysilane, tributoxyethoxysilane, tributoxypropoxysilane. tributoxypentoxysilane, tributoxyhexoxysilane, tributoxyheptoxysilane. tributoxyoctoxysilane, tripentoxyethoxysilane, tripentoxypropoxysilane. tripentoxybutoxysilane, tripentoxyhexoxysilane, tripentoxyhepthoxysilane. tripentoxyoctoxysilane, trihesoxyethoxysilane, trihesoxypropoxysilane. trihesoxybutoxysilane, trihesoxypentoxysilane, trihesoxyheptoxysilane, trihexoxy- octoxysilane, triheptoxyethoxysilane, triheptoxypropoxysilane, triheptoxybutoxysilane, tnheptoxypentoxysilane, tnheptoxyhexoxysilane, trrheptoxyoctoxysilane trioctoxyethoxysilane, trioctoxypropoxysilane, trioctoxybutoxysilane trioctoxypentoxysilane, trioctoxyhexoxysilane, trioctoxyeptoxysilane,

[0067] 3-morpholinopropyltrimethoxysilane, 3 -morpholinopropyltriethoxy silane, 3- morpholinopropyltripropoxysilane, 3 -morpholinopropyltributoxy silane, 3 - morpholinopropyltripentoxysilane, 3 -morpholinoprop yltrihexoxysilane, 3 - morpholinopropyltriheptoxysilane, 3 -morpholinopropyltrioctoxy silane, 3 - morpholinopropylmethyldimethoxysilane, 3-morpholinopropylmethyldiethoxysilane, 3 -morpholinopropylmethyldipropoxy silane, 3 -morpholinopropylmethyldibutoxy silane, 3 -morpholinopropylmethyldipentoxy silane, 3 -morpholinoprop ylmethyldihexoxy silane, 3 -morpholinopropylmethyldiheptoxy silane, 3 -morpholinoprop ylmethyldioctoxy silane, 3 -morpholinopropylethyldimethoxysilane, 3 -morpholinopropylethyldiethoxysilane, 3 - morpholinoprop ylethyldipropoxysilane, 3 -morpholinopropylethyldibutoxy silane, 3- morpholinopropylethyldipentoxy silane, 3 -morpholinoprop ylethyldihexoxy silane, 3- morpholinopropylethyldiheptoxy silane, 3 -morpholinoprop ylethyldioctoxy silane, 3- morpholinopropylpropyldimethoxysilane, 3 -morpholinopropylpropyldiethoxy silane, 3- morpholinopropylpropyldipropoxy silane, 3 -morpholinopropylpropyldibutoxy silane, 3- morpholinopropylpropyldipentoxysilane, 3 -morpholinopropylpropyldiexoxy silane, 3 - morpholinoprop ylpropyldieptoxysilane, 3 -morpholinoprop ylpropyldioctoxysilane, 3- morpholinopropylbutyldimethoxysilane, 3 -morpholinopropylbutyldiethoxy silane, 3- morpholinopropylbutyldipropoxy silane, 3 -morpholinoprop ylbutyldibutoxysilane, 3- morpholinopropylbutyldipentoxysilane, 3 -morpholinoprop ylbutyldihexoxy silane, 3 - morpholinopropylbutyldiheptoxysilane, 3-morpholinopropylbutyldioctoxysilane,

[0068] 3 -piperidinopropyltrimethoxy silane, 3 -piperidinopropyltriethoxy silane, 3 - piperidinopropylmethyldimethoxy silane, 3 -piperidinopropylethyldimethoxy silane, 3- piperidinopropylmethyldiethoxy silane, 3 -piperidinopropylethyldiethoxy silane, N- 3- trimethoxysilylpropyl)-4,5-dihydro-imidazole, A -(3-triethoxysilylpropyl)-4,5-dihydro- imidazole, A / -(3-trimcthoxysilylpropyl)-4,5-imidazolc, A / -(3-tricthoxysilylpropyl)-4,5- imidazole, 3 -hexamethyleneiminopropyltrimethoxy silane, 3 -hexamethyleneiminopropyltriethoxysilane, 3 -hexamethyleneiminoprop ylmethyldimethoxy silane, 3- hexamethyleneiminopropylethyldimethoxysilane, 3 -hexamethyleneiminopropylmethyldiethoxysilane, 3 -hexamethyleneiminopropylethyldiethoxy silane, N-( 1,3- dimethylbutylidene)-3-(triethoxysilyl)-propylamine, or mixtures thereof. 3- morpholinopropylmethyldiethoxysilane, 3-morpholinopropyltriethoxysilane, V-(1,3- dimethyl-butylidene)-3-(triethoxysilyl)propylamine, tetraethoxysilane, or mixtures thereof, are preferred; 3-morpholinopropylmethyldiethoxysilane, 3 -morpholinopropyltriethoxysilane, are particularly preferred.

[0069] Preferably, said alkoxysilane and said lithium-based initiator can be used in molar ratio comprised between 0.3 and 0.9, more preferably comprised between 0.5 and 0.88, even more preferably comprised between 0.6 and 0.85.

[0070] The functionalized styrene-butadiene random copolymer obtained at the end of the process object of the present invention can be recovered from the solution obtained in step (d) by techniques known in the art such as, for example, removal of the solvent by stripping with a stream of steam and subsequent drying in order to remove residual moisture.

[0071] In accordance with a preferred embodiment of the present invention, said step (a) can be carried out at a temperature comprised between 10°C and 70°C, preferably comprised between 30°C and 65°C; however, said step (a) is in any case carried out at a temperature in which the monomers are kept in liquid form.

[0072] In accordance with a preferred embodiment of the present invention, said step (b) can be carried out: at a temperature comprised between 35 °C and 120°C, preferably comprised between 40°C and 100°C; and / or for a time comprised between 5 minutes and 45 minutes, preferably comprised between 5 minutess and 30 minutess.

[0073] In accordance with a preferred embodiment of the present invention, said step (c) can be carried out: at a temperature comprised between 75 °C and 120°C, preferably comprised between 80°C and 100°C; and / or for a time comprised between 4 minutes and 20 minutes, preferably comprised between 5 minutes and 15 minutes.

[0074] In accordance with a preferred embodiment of the present invention, said step (d) can be carried out: at a temperature comprised between 75 °C and 120°C, preferably comprised between 80°C and 100°C; and / or for a time comprised between 4 minutes and 20 minutes, preferably comprised between 5 minutes and 15 minutes.

[0075] The present invention also relates to elastomeric compositions comprising the functionalized styrene-butadiene random copolymer object of the present invention.

[0076] Accordingly, it is a further object of the present invention, an elastomeric composition, in particular a silica-based elastomeric composition, comprising at least one functionalized styrene-butadiene random copolymer reported above.

[0077] It is also a further object of the present invention the use of said elastomeric composition for the production of winter and all-season tires, in particular tire treads. In order to better understand the present invention and to put it into practice, some illustrative and non-limiting examples thereof are reported below.

[0078] The analysis and the characterization methodologies reported below were used.

[0079] Determination of the micro structure ( ’H-NMR)

[0080] The1H-NMR spectra of the functionalized styrene-butadiene random copolymers obtained as reported in the following examples were acquired in order to determine the weight content of styrene and 1,2-vinyl units.

[0081] In particular, the weight percentages of styrene (%) and 1,2-vinyl (%) were determined in accordance with standard ISO 21561:2015 by acquisition of the ’H-NMR spectra.

[0082] The spectrometer used was a Bruker model Avance-neo 300.

[0083] The experimental conditions under which the spectra were acquired were as follows:

[0084] For the acquisition of the 'H-NMR spectra, sample preparation was done by preparing a 3% weight / volume solution of functionalized styrene-butadiene random copolymers in deuterated chloroform (CDCI3, purity > 99.8%, Merck) supplemented with 0.03% TMS (TetraMethyl Silane - Merck) as an internal standard.

[0085] The spectral areas of interest and the related calculations for the determination of the microstructural composition are shown below. ’H-NMR:

[0086] 7.8 ppm - 6.2 ppm: aromatic signals relative to the styrene units (Integral 19+18);

[0087] 6.0 ppm - 5.0 ppm: olefinic signals relative to the 1,4-cis and trans and 1,2-vinyl units (Integral 17);

[0088] 5.0 ppm - 4.3 ppm: olefinic signals relative to the 1,2-vinyl units (Integral 16);

[0089] Determination of the molecular weight

[0090] The determination of the weight- average molecular weight (Mw), number-average molecular weight (Mn), polydispersion index (PDI) (Mw / Mn) and the peak average molecular weight (Mp) of the functionalized styrene-butadiene random copolymers obtained as reported in the following examples was carried out by GPC (“Gel Permeation Chromatography”), using the integrated Agilent Technologies 1200 series instrument that uses fixed-wavelength UV detection (254 nm), operating under the following conditions: six GPC PL columns from Agilent Technologies with dimensions of 300 x 7.5 mm, specifically composed as follows:

[0091] Mettler Toledo analytical balance; laboratory glassware; shaking stirrer; column injection temperature: 25°C; temperature columns and detector: 25 °C; solvent / eluent: tetrahydrofuran (THF) (99+% for HPLC - Merck); flow: 1 mL / min; calculation of the molecular mass by universal calibration curve.

[0092] The aforesaid operating conditions have been constantly monitored through a personal computer provided with Agilent GPC / SEC software from Agilent Technologies.

[0093] The calibration was carried out as follows.

[0094] Four tetrahydrofuran (THF) solutions (99+% by HPLC - Merck) were prepared, each containing three polystyrene (PS) standards having a different nominal peak molecular weight (Mp) and equal concentrations: the choice of molecular weights was carried out in such a way that the chromatographic peaks eluted were well separated. The range of the different nominal peak molecular weights (Mp) of the aforesaid standards used for the calibration curve was comprised between 3 kDa and 10 kDa approximately.

[0095] The different solutions were prepared, under stirring, at room temperature (25°C).

[0096] The calibration curve was calculated by means of a personal computer equipped with the aforesaid Agilent GPC / SEC software from Agilent Technologies, using a 3rd- order polynomial function: by means of said polynomial, it was possible to obtain the aforesaid molecular weight information.

[0097] Determination of Mooney viscosity

[0098] The determination of Mooney Viscosity was carried out at a temperature of 100°C using a Mooney Alpha Technologies MV2000E Viscometer, in accordance with standard ASTM DI 646- 19a using a large rotor (L) and with the following times:

[0099] 1 minute of preheating;

[0100] 4-minute of test (MLI+4@ 100°C) with rotor rotation speed equal to 2 rpm.

[0101] Determination of the glass transition temperature (Tg)

[0102] The thermal analysis DSC (“Differential Scanning Calorimetry”), in order to determine the glass transition temperature (Tg) of the functionalized styrene-butadiene random copolymers obtained as reported in the following examples, was carried out by means of the Discovery DSC Differential Scanning Calorimetry from Waters_TA Instruments, using the following thermal cycle: thermo statting at a temperature equal to -120°C; heating from -120°C to 100°C at a speed of 10°C / min. (1st cycle); thermo statting at a temperature equal to -120°C; heating from -120°C to + 100°C at a speed of 10°C / minute (2nd cycle).

[0103] The determination of the glass transition temperature (Tg) was carried out on the 2nd cycle heating.

[0104] Determination of the polystyrene blocks

[0105] The determination of the polystyrene blocks in the functionalized styrenebutadiene random copolymers obtained as reported in the following examples was carried out as follows.

[0106] For this purpose, the functionalized styrene-butadiene random copolymers were degraded by ozonolysis of the butadiene double bonds in order to reach a quantitative assessment of the distribution of the polystyrene blocks by means of high-performance liquid chromatography (HPLC) of the oligomers deriving from ozonolysis.

[0107] For this purpose, an Agilent 1200 series HPLC instrument was used equipped with:

[0108] ALS autosampler; quaternary pump;

[0109] UV VWD detector;

[0110] MS analyser of the Agilent 6220 MS-QTOF type.

[0111] The main instrumental parameters and operating conditions adopted are reported below:

[0112] HPLC:

[0113] MS QTOF:

[0114] The instrument is connected to a computer equipped with the Agilent Masshunter®management software package.

[0115] The content of polystyrene blocks (i.e. polymer chain sections deriving from the homopolymerisation of a number of molecules of styrene greater than or equal to 16) was calculated in accordance with the following equations: for n > 16 wherein:

[0116] A x KSTYx 100

[0117] SB %T0T= — - — - m

[0118] ABx KSTYx 10000 m = mass;

[0119] SB%TOT = polystyrene blocks in % m / m with respect to the total weight of the functionalized styrene-butadiene random copolymer;

[0120] SB%SL = polystyrene blocks in % m / m with respect to the bound styrene (SL);

[0121] KSTY = polystyrene calibration constant (g / Area); m = mass of the purified sample in g;

[0122] SL = bound styrene in % m / m;

[0123] SR = randomly arranged styrene = S I%SL

[0124] Sn%SR = Sn sequence (containing more than 16 molecules of styrene) in % area with respect to SR;

[0125] Sn%SL = sequence S (containing more than 16 molecules of styrene) in % area with respect to SL;

[0126] An= sum of the areas of all sequences SnVmwith the same n for n > 16, wherein Vmis the vinyl% (i.e. 1,2-vinyl units) not attacked by ozonolysis;

[0127] Atot = sum of the areas of all sequences SnVmfor n < 16;

[0128] AB = Block area = Anfor n > 16.

[0129] Further details regarding the methodology used for the above determination can be found in the article by Pattuelli M. E. et al., “Journal of Chromatography A” (1994), Vol. 665(1), pp. 117-123.

[0130] Measurement of tensile properties

[0131] The modulus of elasticity at 100% elongation (M100%), 200% elongation (M200%) and 300% elongation (M300%), the tensile strength (TS), the elongation at break (EB), and the energy at break (EB), were measured in accordance with standard ASTM D412-16(2021) Test Method A, using the ITW Instron instrument mod. 5966 on the vulcanized elastomeric compositions.

[0132] Measurement of the rheometric properties The rheometric properties were measured as reported in ASTM method D5289- 19a using the MDR2000 rheometer by Alpha Technologies on the unvulcanized elastomeric compositions. In particular, the following rheometric properties were measured: Min. torque (minimum torque - ML), Max Torque (maximum torque - MH), “Scorch time TS1” (time in which an increase by 1 dNm occurs with respect to ML),

[0133] “Scorch time TS2” (time in which an increase by 2 dNm occurs with respect to ML),

[0134] “Scorch time TS5” (time in which an increase by 5 dNm occurs with respect to ML),

[0135] T’5 (time in which the torque curve reaches 5% of the increase MH-ML), T’50 (time in which the torque curve reaches 50% of the increase MH-ML), T’90 (time in which the torque curve reaches 90% of the increase MH-ML), T’95 (time in which the torque curve reaches 95% of the increase MH-ML) and RH (maximum slope of the torque curve with respect to time). More in particular, T’x was calculated according to the following equation:

[0136] T’x = time in which the increase ( VIL + x X (~~~)^ °f the torque curve is recorded.

[0137] Measurement of the tear strength (TS)

[0138] Tear strength was measured in accordance with standard ISO 34-2:2022, Part 2, “Small (Delft) test pieces” using the ITW Instron instrument mod. 5966 on the vulcanized elastomeric compositions.

[0139] Measurement of the abrasion resistance (AR)

[0140] Abrasion resistance (AR) was measured in accordance with standard ASTM D 5963-22 using the Gibitre Instruments ABRASION CHECK instrument on the vulcanized elastomeric compositions.

[0141] Measurement of the Heat Build-Up (HBU)

[0142] The Heat Build-Up (HBU) was measured in accordance with standard ASTM D623-07 (2019)el at a starting temperature equal to 25°C with an analysis time of 25 minutes, using the Goodrich DOLI Type 1170 instrument on the vulcanized elastomeric compositions.

[0143] Measurement of the Tan delta (Tan 5)

[0144] Tan delta (Tan 6) at 0°C and at -10°C was measured in accordance with standard ISO / DIS 23508:2021 except for the frequency of the temperature scan, done at 1 Hz instead of 10 Hz as indicated in said ISO method on the vulcanized elastomeric compositions. A measurement was also made at 10 Hz, at 60°C, 5% strain (“strain sweep test”) on the vulcanized elastomeric compositions.

[0145] The aforesaid measurements were carried out using the TA Instruments ARES II instrument.

[0146] Measurement of the hardness

[0147] Hardness was measured in accordance with standard ASTM D2240- 15(2021) using the Gibitre Instruments Automatic Hardness Check durometer on the vulcanized elastomeric compositions(indentation time = 3 seconds).

[0148] Measurement of the elastic yield (“Rebound Test”)

[0149] Elastic yield (rebound test) was measured in accordance with standard ASTM D7121-05 using the Gibitre Instruments Rebound Check pendulum on the vulcanized elastomeric compositions.

[0150] EXAMPLE 1 (comparative)

[0151] 133.4 kg of anhydrous cyclohexane (Cepsa Italia S.p.A.) were placed in a 300- litre batch reactor equipped with stirrer and temperature regulation system and, subsequently, 2.7 kg of anhydrous styrene (Versalis S.p.A.), 15.5 kg of anhydrous 1,3- butadiene (Versalis S.p.A.) and 127 g (50 ppm with respect to cyclohexane) of 2- (ethoxymethyl)-tetrahydrofuran (THFA-ethyl) (Thomas Swan) [5% by weight solution prepared by dilution in anhydrous cyclohexane (Cepsa Italia S.p.A.)] were added obtaining a reaction mixture.

[0152] The temperature regulation system was set so as to have a reaction mixture temperature equal to 40°C, defined as trigger temperature (T0. Once the trigger temperature (T0 was reached, 482 ml (0.045 phm) of a solution of n-butyl lithium at 2.3% by weight prepared by dilution in anhydrous cyclohexane (Cepsa Italia S.p.A.) of a 24% by weight solution n-butyl lithium in n-hexane (FMC Chemicals) were added: the temperature regulation system was set at +3 °C with respect to the temperature of the reaction mixture in order to guarantee adiabaticity to the system and follow the temperature increase of said reaction mixture obtained by virtue of the exothermic character of the reaction until reaching, after 23 minutes from the insertion of the n-butyl lithium, a final temperature (peak temperature) equal to 97°C, obtaining a substantially complete conversion of the charged monomers (styrene = 99.5%; 1,3-butadiene = 99.9%). After 5 minutes had elapsed from reaching the peak temperature, 47 ml of tin tetrachloride (Merck) [4% by weight solution, obtained by dilution in anhydrous cyclohexane (Cepsa Italia S.p.A.)] corresponding to the theoretical 20% coupling efficiency were added. After 10 minutes, at said temperature (i.e. 97°C), under stirring, 48.5 ml of 3-morpholinopropylmethyldiethoxysilane (2 M solution in cyclohexane - ShinEtsu) corresponding to the theoretical 80% of functionalization were added.

[0153] The polymer solution obtained, after 10 minutes, was discharged from the reactor, into a tank where it was stabilized with 0.35 phr (“phr” indicates the parts by weight of a given component per 100 parts by weight of copolymer) of 4,6-bis(octylthiomethyl)- o-cresol (phenolic antioxidant Irganox®1520 - Basf) and the whole was sent to the desolventization section by stripping with a stream of steam, under stirring.

[0154] After removal of the solvent, the copolymer was collected in the form of wet lumps, sent to a calender at room temperature (25°C) and then to another calender at 80°C for drying and removal of residual moisture.

[0155] The obtained functionalized styrene-butadiene random copolymer was subjected to the characterizations reported above and the results obtained are reported in Table 1. EXAMPLE 2 (comparative)

[0156] 133.4 kg of anhydrous cyclohexane (Cepsa Italia S.p.A.) were placed in a 300- litre batch reactor equipped with stirrer and temperature regulation system and, subsequently, 2.7 kg of anhydrous styrene (Versalis S.p.A.), 15.5 kg of anhydrous 1,3- butadiene (Versalis S.p.A.) and 127 g of 2-(ethoxymethyl)-tetrahydrofuran (THFA- ethyl) (Thomas Swan) [5% by weight solution prepared by dilution in anhydrous cyclohexane (Cepsa Italia S.p.A.)] were added (50 ppm with respect to cyclohexane) obtaining a reaction mixture.

[0157] The temperature regulation system was set so as to have a reaction mixture temperature equal to 40°C, defined as trigger temperature (Ti). Once the trigger temperature (Ti) was reached, 450 ml (0.037 phm) of a solution of n-butyl lithium at 2.3% by weight prepared by dilution in anhydrous cyclohexane (Cepsa Italia S.p.A.) of a 24% by weight solution n-butyl lithium in n-hexane (FMC Chemicals) were added: the temperature regulation system was set at +3 °C with respect to the temperature of the reaction mixture in order to guarantee adiabaticity to the system and follow the temperature increase of said reaction mixture obtained by virtue of the exothermic character of the reaction until reaching, after 23 minutes from the insertion of the n-butyl lithium, a final temperature (peak temperature) equal to 97.6°C, obtaining a substantially complete conversion of the charged monomers (styrene = 99.5%; 1,3-butadiene = 99.9%). After 5 minutes had elapsed from reaching the peak temperature, 40.2 ml of tin tetrachloride (Merck) [4% by weight solution, obtained by dilution in anhydrous cyclohexane n-hexane (Cepsa Italia S.p.A.)] corresponding to the theoretical 20% coupling efficiency were added. After 10 minutes, at said temperature (i.e. 97.6°C), under stirring, 40.4 ml of 3-morpholinopropylmethyldiethoxysilane (2 M solution in cyclohexane - ShinEtsu) corresponding to the theoretical 80% of functionalization were added.

[0158] The polymer solution obtained, after 10 minutes, was discharged from the reactor, into a tank where it was stabilized with 0.35 phr (“phr” indicates the parts by weight of a given component per 100 parts by weight of copolymer) of 4,6-bis(octylthiomethyl)- o-cresol (phenolic antioxidant Irganox®1520 - Basf) and the whole was sent to the desolventization section by stripping with a stream of steam, under stirring.

[0159] After removal of the solvent, the copolymer was collected in the form of wet lumps, sent to a calender at room temperature (25°C) and then to another calender at 80°C for drying and removal of residual moisture.

[0160] The obtained functionalized styrene-butadiene random copolymer was subjected to the characterizations reported above and the results obtained are reported in Table 1. EXAMPLE 3 (comparative)

[0161] 133.4 kg of anhydrous cyclohexane (Cepsa Italia S.p.A.) were placed in a 300- litre batch reactor equipped with stirrer and temperature regulation system and, subsequently, 2.7 kg of anhydrous styrene (Versalis S.p.A.) and 15.5 kg of anhydrous 1,3-butadiene (Versalis S.p.A.) were added obtaining a reaction mixture.

[0162] The temperature regulation system was set so as to have a reaction mixture temperature equal to 38°C, defined as trigger temperature (Ti). Once the trigger temperature (Ti) was reached, 433 ml (0.04 phm) of a solution of n-butyl lithium at 2.3% by weight prepared by dilution in anhydrous cyclohexane (Cepsa Italia S.p.A.) of a 24% by weight solution n-butyl lithium in n-hexane (FMC Chemicals) were added: the temperature regulation system was set at +3 °C with respect to the temperature of the reaction mixture in order to guarantee adiabaticity to the system and follow the temperature increase of said reaction mixture obtained by virtue of the exothermic character of the reaction. After reaching a temperature T i equal to 84.2°C (AT = 46.2°C), after 27 minutes from the insertion of the n -butyl lithium, 507.2 g (200 ppm with respect to cyclohexane) of 2-(ethoxymethyl)-tetrahydrofuran (THFA-ethyl) (Thomas Swan) [5.3% by weight solution prepared by dilution in anhydrous cyclohexane (Cepsa Italia S.p.A.)] were added and, after 39 minutes from the insertion of the n-butyl lithium, a final temperature (peak temperature) equal to 99.5 °C was reached, obtaining a substantially complete conversion of the charged monomers (styrene = 99.5%; 1,3- butadiene = 99.9%). After 5 minutes had elapsed from reaching the peak temperature, 60.3 ml of tin tetrachloride (Merck) [4% by weight solution, obtained by dilution in anhydrous cyclohexane n-hexane (Cepsa Italia S.p.A.)] corresponding to the theoretical 25% coupling efficiency were added. After 10 minutes, at said temperature (i.e. 99.5°C), under stirring, 37.9 ml of 3-morpholinopropylmethyldiethoxysilane (2 M solution in cyclohexane - ShinEtsu) corresponding to the theoretical 75% of functionalization were added.

[0163] The polymer solution obtained, after 10 minutes, was discharged from the reactor, into a tank where it was stabilized with 0.35 phr (“phr” indicates the parts by weight of a given component per 100 parts by weight of copolymer) of 4,6-bis(octylthiomethyl)- o-cresol (phenolic antioxidant Irganox®1520 - Basf) and the whole was sent to the desolventization section by stripping with a stream of steam, under stirring.

[0164] After removal of the solvent, the copolymer was collected in the form of wet lumps, sent to a calender at room temperature (25°C) and then to another calender at 80°C for drying and removal of residual moisture.

[0165] The obtained functionalized styrene-butadiene random copolymer was subjected to the characterizations reported above and the results obtained are reported in Table 1. EXAMPLE 4 (comparative)

[0166] 133.4 kg of anhydrous cyclohexane (Cepsa Italia S.p.A.) were placed in a 300- litre batch reactor equipped with stirrer and temperature regulation system and, subsequently, 2.7 kg of anhydrous styrene (Versalis S.p.A.) and 15.5 kg of anhydrous 1,3-butadiene (Versalis S.p.A.) were added obtaining a reaction mixture.

[0167] The temperature regulation system was set so as to have a reaction mixture temperature equal to 36.5°C, defined as trigger temperature (Ti). Once the trigger temperature (Ti) was reached, 411 ml (0.038 phm) of a solution of n-butyl lithium at 2.3% by weight prepared by dilution in anhydrous cyclohexane (Cepsa Italia S.p.A.) of a 24% by weight solution n-butyl lithium in n-hexane (FMC Chemicals) were added: the temperature regulation system was set at +3 °C with respect to the temperature of the reaction mixture in order to guarantee adiabaticity to the system and follow the temperature increase of said reaction mixture obtained by virtue of the exothermic character of the reaction. After reaching a temperature Ti equal to 76.5°C (AT = 40°C), after 45 minutes from the insertion of the n -butyl lithium, 507.2 g (200 ppm with respect to cyclohexane) of 2-(ethoxymethyl)-tetrahydrofuran (THFA-ethyl) (Thomas Swan) [5.3% by weight solution prepared by dilution in anhydrous cyclohexane (Cepsa Italia S.p.A.)] were added and, after 54 minutes from the insertion of the n-butyl lithium, a final temperature (peak temperature) equal to 93.7°C was reached, obtaining a substantially complete conversion of the charged monomers (styrene = 99.5%; 1,3- butadiene = 99.9%). After 5 minutes had elapsed from reaching the peak temperature, 60.3 ml of tin tetrachloride (Merck) [4% by weight solution, obtained by dilution in anhydrous cyclohexane n-hexane (Cepsa Italia S.p.A.)] corresponding to the theoretical 25% coupling efficiency were added. After 10 minutes, at said temperature (i.e. 93.7°C), under stirring, 37.9 ml of 3-morpholinopropylmethyldiethoxysilane (2 M solution in cyclohexane - ShinEtsu) corresponding to the theoretical 75% of functionalization were added.

[0168] The polymer solution obtained, after 10 minutes, was discharged from the reactor, into a tank where it was stabilized with 0.35 phr (“phr” indicates the parts by weight of a given component per 100 parts by weight of copolymer) of 4,6-bis(octylthiomethyl)- o-cresol (phenolic antioxidant Irganox®1520 - Basf) and the whole was sent to the desolventization section by stripping with a stream of steam, under stirring.

[0169] After removal of the solvent, the copolymer was collected in the form of wet lumps, sent to a calender at room temperature (25°C) and then to another calender at 80°C for drying and removal of residual moisture. The obtained functionalized styrene-butadiene random copolymer was subjected to the characterizations reported above and the results obtained are reported in Table 1. EXAMPLE 5 (invention)

[0170] 133.4 kg of anhydrous cyclohexane (Cepsa Italia S.p.A.) were placed in a 300- litre batch reactor equipped with stirrer and temperature regulation system and, subsequently, 2.7 kg of anhydrous styrene (Versalis S.p.A.) and 15.5 kg of anhydrous 1,3-butadiene (Versalis S.p.A.) were added obtaining a reaction mixture.

[0171] The temperature regulation system was set so as to have a reaction mixture temperature equal to 35°C, defined as trigger temperature (Ti). Once the trigger temperature (Ti) was reached, 434 ml (0.04 phm) of a solution of n-butyl lithium at 2.3% by weight prepared by dilution in anhydrous cyclohexane (Cepsa Italia S.p.A.) of a 24% by weight solution n-butyl lithium in n-hexane (FMC Chemicals) were added: the temperature regulation system was set at +3 °C with respect to the temperature of the reaction mixture in order to guarantee adiabaticity to the system and follow the temperature increase of said reaction mixture obtained by virtue of the exothermic character of the reaction. After reaching a temperature T i equal to 50.7°C (AT = 15.7°C), after 27 minutes from the insertion of the n -butyl lithium, 507.2 g (200 ppm with respect to cyclohexane) of 2-(ethoxymethyl)-tetrahydrofuran (THFA-ethyl) (Thomas Swan) [5.3% by weight solution prepared by dilution in anhydrous cyclohexane (Cepsa Italia S.p.A.)] were added and, after 44 minutes from the insertion of the n-butyl lithium, a final temperature (peak temperature) equal to 93.2°C was reached, obtaining a substantially complete conversion of the charged monomers (styrene = 99.5%; 1,3- butadiene = 99.9%). After 5 minutes had elapsed from reaching the peak temperature, 81.4 ml of tin tetrachloride (Merck) [4% by weight solution, obtained by dilution in anhydrous cyclohexane n-hexane (Cepsa Italia S.p.A.)] corresponding to the theoretical 25% coupling efficiency were added. After 10 minutes, at said temperature (i.e. 93.2°C), under stirring, 37.9 ml of 3-morpholinopropylmethyldiethoxysilane (2 M solution in cyclohexane - ShinEtsu) corresponding to the theoretical 75% of functionalization were added.

[0172] The polymer solution obtained, after 10 minutes, was discharged from the reactor, into a tank where it was stabilized with 0.35 phr (“phr” indicates the parts by weight of a given component per 100 parts by weight of copolymer) of 4,6-bis(octylthiomethyl)- o-cresol (phenolic antioxidant Irganox®1520 - Basf) and the whole was sent to the desolventization section by stripping with a stream of steam, under stirring.

[0173] After removal of the solvent, the copolymer was collected in the form of wet lumps, sent to a calender at room temperature (25°C) and then to another calender at 80°C for drying and removal of residual moisture.

[0174] The obtained functionalized styrene-butadiene random copolymer was subjected to the characterizations reported above and the results obtained are reported in Table 1. EXAMPLE 6 (invention)

[0175] 133.4 kg of anhydrous cyclohexane (Cepsa Italia S.p.A.) were placed in a 300- litre batch reactor equipped with stirrer and temperature regulation system and, subsequently, 2.7 kg of anhydrous styrene (Versalis S.p.A.) and 15.5 kg of anhydrous 1,3-butadiene (Versalis S.p.A.) were added obtaining a reaction mixture.

[0176] The temperature regulation system was set so as to have a reaction mixture temperature equal to 34.3°C, defined as trigger temperature (Ti). Once the trigger temperature (Ti) was reached, 410 ml (0.038 phm) of a solution of n-butyl lithium at 2.3% by weight prepared by dilution in anhydrous cyclohexane (Cepsa Italia S.p.A.) of a 24% by weight solution n-butyl lithium in n-hexane (FMC Chemicals) were added: the temperature regulation system was set at +3 °C with respect to the temperature of the reaction mixture in order to guarantee adiabaticity to the system and follow the temperature increase of said reaction mixture obtained by virtue of the exothermic character of the reaction. Once a temperature Ti equal to 57.3 °C (AT = 23 °C) was reached, after 40 minutes from the insertion of the n-butyl lithium, 507.2 g of 2- (ethoxymethyl)-tetrahydrofuran (THFA-ethyl) (Thomas Swan) [5.3% by weight solution prepared by dilution in anhydrous cyclohexane (Cepsa Italia S.p.A.)] (200 ppm with respect to cyclohexane) were added and, after 52 minutes from the insertion of the n-butyl lithium, a final temperature (peak temperature) equal to 92.4°C was reached, obtaining a substantially complete conversion of the charged monomers (styrene = 99.5%; 1,3-butadiene = 99.9%). After 5 minutes had elapsed from reaching the peak temperature, 60.3 ml of tin tetrachloride (Merck) [4% by weight solution, obtained by dilution in anhydrous cyclohexane n-hexane (Cepsa Italia S.p.A.)] corresponding to the theoretical 25% coupling efficiency were added. After 10 minutes, at said temperature (i.e. 92.4°C), under stirring, 37.9 ml of 3-morpholinopropylmethyldiethoxysilane (2 M solution in cyclohexane - ShinEtsu) corresponding to the theoretical 75% of functionalization were added.

[0177] The polymer solution obtained, after 10 minutes, was discharged from the reactor, into a tank where it was stabilized with 0.35 phr (“phr” indicates the parts by weight of a given component per 100 parts by weight of copolymer) of 4,6-bis(octylthiomethyl)- o-cresol (phenolic antioxidant Irganox®1520 - Basf) and the whole was sent to the desolventization section by stripping with a stream of steam, under stirring.

[0178] After removal of the solvent, the copolymer was collected in the form of wet lumps, sent to a calender at room temperature (25°C) and then to another calender at 80°C for drying and removal of residual moisture.

[0179] The obtained functionalized styrene-butadiene random copolymer was subjected to the characterizations reported above and the results obtained are reported in Table 1. EXAMPLE 7 (invention)

[0180] 133.4 kg of anhydrous cyclohexane (Cepsa Italia S.p.A.) were placed in a 300- litre batch reactor equipped with stirrer and temperature regulation system and, subsequently, 2.7 kg of anhydrous styrene (Versalis S.p.A.) and 15.5 kg of anhydrous 1,3-butadiene (Versalis S.p.A.) were added obtaining a reaction mixture.

[0181] The temperature regulation system was set so as to have a reaction mixture temperature equal to 34.7°C, defined as trigger temperature (Ti). Once the trigger temperature (Ti) was reached, 409 ml (0.038 phm) of a solution of n-butyl lithium at 2.3% by weight prepared by dilution in anhydrous cyclohexane (Cepsa Italia S.p.A.) of a 24% by weight solution n-butyl lithium in n-hexane (FMC Chemicals) were added: the temperature regulation system was set at +3 °C with respect to the temperature of the reaction mixture in order to guarantee adiabaticity to the system and follow the temperature increase of said reaction mixture obtained by virtue of the exothermic character of the reaction. After reaching a temperature Ti equal to 58.7°C (AT = 24°C), after 27 minutes from the insertion of the n-butyl lithium, 507.2 g (200 ppm with respect to cyclohexane) of 2-(ethoxymethyl)-tetrahydrofuran (THFA-ethyl) (Thomas Swan) [5.3% by weight solution prepared by dilution in anhydrous cyclohexane (Cepsa Italia S.p.A.)] were added and, after 60 minutes from the insertion of the n-butyl lithium, a final temperature (peak temperature) equal to 92.6°C was reached, obtaining a substantially complete conversion of the charged monomers (styrene = 99.5%; 1,3- butadiene = 99.9%). After 5 minutes had elapsed from reaching the peak temperature, 59.8 ml of tin tetrachloride (Merck) [4% by weight solution, obtained by dilution in anhydrous cyclohexane n-hcxanc (Cepsa Italia S.p.A.)] corresponding to the theoretical 20% coupling efficiency were added. After 10 minutes, at said temperature (i.e. 92.6°C), under stirring, 40.4 ml of 3-morpholinopropyltriethoxysilane (2 M solution in cyclohexane - ShinEtsu) corresponding to the theoretical 80% of functionalization were added.

[0182] The polymer solution obtained, after 10 minutes, was discharged from the reactor, into a tank where it was stabilized with 0.35 phr (“phr” indicates the parts by weight of a given component per 100 parts by weight of copolymer) of 4,6-bis(octylthiomethyl)- o-cresol (phenolic antioxidant Irganox®1520 - Basf) and the whole was sent to the desolventization section by stripping with a stream of steam, under stirring.

[0183] After removal of the solvent, the copolymer was collected in the form of wet lumps, sent to a calender at room temperature (25°C) and then to another calender at 80°C for drying and removal of residual moisture.

[0184] The obtained functionalized styrene-butadiene random copolymer was subjected to the characterizations reported above and the results obtained are reported in Table 1. EXAMPLE 8 (invention)

[0185] 133.4 kg of anhydrous cyclohexane (Cepsa Italia S.p.A.) were placed in a 300- litre batch reactor equipped with stirrer and temperature regulation system and, subsequently, 2.7 kg of anhydrous styrene (Versalis S.p.A.) and 15.5 kg of anhydrous 1,3-butadiene (Versalis S.p.A.) were added obtaining a reaction mixture.

[0186] The temperature regulation system was set so as to have a reaction mixture temperature equal to 35.2°C, defined as trigger temperature (Ti). Once the trigger temperature (Ti) was reached, 409 ml (0.038 phm) of a solution of n-butyl lithium at 2.3% by weight prepared by dilution in anhydrous cyclohexane (Cepsa Italia S.p.A.) of a 24% by weight solution n-butyl lithium in n-hexane (FMC Chemicals) were added: the temperature regulation system was set at +3 °C with respect to the temperature of the reaction mixture in order to guarantee adiabaticity to the system and follow the temperature increase of said reaction mixture obtained by virtue of the exothermic character of the reaction. Once a temperature Ti equal to 58.5°C (AT = 23.3°C) was reached, after 39 minutes from the insertion of the n-butyl lithium, 507.2 g (200 ppm with respect to cyclohexane) of 2-(ethoxymethyl)-tetrahydrofuran (THFA-ethyl) (Thomas Swan) [5.3% by weight solution prepared by dilution in anhydrous cyclohexane (Cepsa Italia S.p.A.)] (200 ppm with respect to cyclohexane) were added and, after 48 minutes from the insertion of the n-butyl lithium, a final temperature (peak temperature) equal to 95.3°C was reached, obtaining a substantially complete conversion of the charged monomers (styrene = 99.5%; 1,3-butadiene = 99.9%). After 5 minutes had elapsed from reaching the peak temperature, 58.9 ml of tin tetrachloride (Merck) [4% by weight solution, obtained by dilution in anhydrous cyclohexane n- hexane (Cepsa Italia S.p.A.)] corresponding to the theoretical 20% coupling efficiency were added. After 10 minutes, at said temperature (i.e. 95.3°C), under stirring, 40.4 ml of 3 -morpholinopropyltriethoxy silane (2 M solution in cyclohexane - ShinEtsu) corresponding to the theoretical 80% of functionalization were added.

[0187] The polymer solution obtained, after 10 minutes, was discharged from the reactor, into a tank where it was stabilized with 0.35 phr (“phr” indicates the parts by weight of a given component per 100 parts by weight of copolymer) of 4,6-bis(octylthiomethyl)- o-cresol (phenolic antioxidant Irganox®1520 - Basf) and the whole was sent to the desolventization section by stripping with a stream of steam, under stirring.

[0188] After removal of the solvent, the copolymer was collected in the form of wet lumps, sent to a calender at room temperature (25°C) and then to another calender at 80°C for drying and removal of residual moisture.

[0189] The obtained functionalized styrene-butadiene random copolymer was subjected to the characterizations reported above and the results obtained are reported in Table 1. EXAMPLE 9 (invention)

[0190] 133.4 kg of anhydrous cyclohexane (Cepsa Italia S.p.A.) were placed in a 300- litre batch reactor equipped with stirrer and temperature regulation system and, subsequently, 2.7 kg of anhydrous styrene (Versalis S.p.A.) and 15.5 kg of anhydrous 1,3-butadiene (Versalis S.p.A.) were added obtaining a reaction mixture. The temperature regulation system was set so as to have a reaction mixture temperature equal to 35°C, defined as trigger temperature (TQ. Once the trigger temperature (Ti) was reached, 409 ml (0.038 phm) of a solution of n-butyl lithium at 2.3% by weight prepared by dilution in anhydrous cyclohexane (Cepsa Italia S.p.A.) of a 24% by weight solution n-butyl lithium in n-hexane (FMC Chemicals) were added: the temperature regulation system was set at +3 °C with respect to the temperature of the reaction mixture in order to guarantee adiabaticity to the system and follow the temperature increase of said reaction mixture obtained by virtue of the exothermic character of the reaction. After reaching a temperature T i equal to 57.8°C (AT = 22.8°C), after 42 minutes from the insertion of the n -butyl lithium, 507.2 g (200 ppm with respect to cyclohexane) of 2-(ethoxymethyl)-tetrahydrofuran (THFA-ethyl) (Thomas Swan) [5.3% by weight solution prepared by dilution in anhydrous cyclohexane (Cepsa Italia S.p.A.)] were added and, after 52 minutes from the insertion of the n-butyl lithium, a final temperature (peak temperature) equal to 96.9°C was reached, obtaining a substantially complete conversion of the charged monomers (styrene = 99.5%; 1,3- butadiene = 99.9%). After 5 minutes had elapsed from reaching the peak temperature, 58.9 ml of tin tetrachloride (Merck) [4% by weight solution, obtained by dilution in anhydrous cyclohexane n-hexane (Cepsa Italia S.p.A.)] corresponding to the theoretical 25% coupling efficiency were added. After 10 minutes, at said temperature (i.e. 93.2°C), under stirring, 40.4 ml of 3-morpholinopropyltriethoxysilane (2 M solution in cyclohexane - ShinEtsu) corresponding to the theoretical 80% of functionalization were added.

[0191] The polymer solution obtained, after 10 minutes, was discharged from the reactor, into a tank where it was stabilized with 0.35 phr (“phr” indicates the parts by weight of a given component per 100 parts by weight of copolymer) of 4,6-bis(octylthiomethyl)- o-cresol (phenolic antioxidant Irganox®1520 - Basf) and the whole was sent to the desolventization section by stripping with a stream of steam, under stirring.

[0192] After removal of the solvent, the copolymer was collected in the form of wet lumps, sent to a calender at room temperature (25°C) and then to another calender at 80°C for drying and removal of residual moisture.

[0193] The obtained functionalized styrene-butadiene random copolymer was subjected to the characterizations reported above and the results obtained are reported in Table 1.

[0194] The characterizations reported above and the results obtained are reported in Table 1.

[0195] EXAMPLE 10 of a silica-based elastomeric

[0196] The functionalized styrene-butadiene random copolymer obtained in accordance with Example 9 was used to produce a silica-based elastomeric composition usable in winter tire tread.

[0197] Below are the quantities of the components used for the production of said elastomeric composition (phr = parts by weight of a given component of the elastomeric composition compared to 100 parts by weight of the elastomer(s) used):

[0198] 75 phr of functionalized styrene-butadiene random copolymer obtained in Example 9;

[0199] 25 phr of polybutadiene with a high content of 1,4-cis units (Europrene® Neocis BR40 - Versalis S.p.A);

[0200] 90 phr of Ultrasil® GRVN3 silica (Evonik);

[0201] 7.2 phr of SI75® silane (Evonik);

[0202] 48 phr of Eni Clematis TD oil (“Treated Distillate Aromatic Extract” - TDAE) (Eni S.p.A);

[0203] 2 phr of Riowax® 721 (paraffin wax) (Andrea Gallo Di Luigi s.r.l.);

[0204] 4.5 phr of 6PPD (antioxidant): N-(l,3-dimethylbutyl)-N’-phenyl-p-phenylene- diamine (Brenntag);

[0205] 3.125 phr of zinc oxide (ZNO AKTIVE 80GE F 140 - Deltagran);

[0206] 3 phr of stearic acid (Carlo Erba);

[0207] 2 phr of sulphur (S 80 GE F 140 - Deltagran);

[0208] 3.25 phr CBS (accelerator) (N-cyclohexyl-2-benzothiazyl-sulfenamide - CBS 80 GE F 140 - Deltagran);

[0209] 2.75 phr DPG (accelerator) (diphenyl guanidine - DPG 80 GE F 140 - Deltagran).

[0210] The elastomeric composition was prepared as follows:

[0211] 1st Step - Masterbatch preparation

[0212] The components were inserted into a Brabender model 350S internal mixer operating as follows: fill factor: 0.7; rotor speed: 60 rpm; set temperature: 110°C;

[0213] O’: insert the elastomers [functionalized styrene-butadiene random copolymer obtained in Example 9 and polybutadiene (Europrene® Neocis BR40)] into the mixer;

[0214] 1’: add 2 / 3 of the quantity of silica (Ultrasil® GRVN3) and all the silane (SI75®);

[0215] 2’: add the remaining aliquot of silica (Ultrasil® GRVN3), oil (Eni Clematis TD), paraffin wax (Riowax ® 721) and antioxidant (6PPD);.

[0216] 3’: lift the presser piston, clean the orifice and reposition the presser piston;

[0217] 4’: mix the elastomeric composition;

[0218] 7’: once the temperature equal to 155 ±5 °C has been reached, discharge the elastomeric composition.

[0219] 2nd Step

[0220] The elastomeric composition obtained in the 1st Step and the further components were inserted into a Brabender model 350S internal mixer operating as follows: rotor speed: 60 rpm; set temperature: 110°C;

[0221] O’: insert the elastomeric composition obtained in the 1st Step into the mixer;

[0222] 0.5’: add zinc oxide (ZNO AKTIVE 80GE F 140) and the stearic acid.

[0223] 1.5’: lift the presser piston, clean the orifice and reposition the presser piston;

[0224] 2’: mix the elastomeric composition;

[0225] 4’: once the temperature equal to 145°C has been reached, discharge the elastomeric composition.

[0226] 3rd Step

[0227] The elastomeric composition obtained in the 2nd Step and the further components were inserted into a Brabender model 350S internal mixer operating as follows: rotor speed: 60 rpm; set temperature: 50°C;

[0228] O’: insert 1 / 3 of the elastomeric composition obtained in the 2nd Step into the mixer; 0.5’: add sulphur (S 80 GE F 140) and the accelerators (CBS 80 GE F 140 and DPG 80 GE F 140) and the remaining elastomeric composition obtained in the 2nd Step;

[0229] 2.5’: mix and once the temperature of 110°C has been reached, discharge the elastomeric composition. At the end of the 3rd step, the elastomeric composition was cooled by 10 passes between two conditioned rollers at a temperature of 50°C; after each pass, the material was overturned and the gap between the rollers was adjusted in such a way as to obtain a sheet of material 2 mm thick.

[0230] The sheet was subsequently cut into slabs which were vulcanized by compression moulding, at 160°C, for 15 minutes.

[0231] The vulcanized and unvulcanized elastomeric composition obtained was subjected to the characterizations reported above: the results obtained are reported in Tables 2, 3, 4, 5, 6, 7, 8 and 9 that follow.

[0232]

[0233] Table 1

[0234] Characterization of functionalized styrene-butadiene random copolymers

[0235] Table 2

[0236] Table 3 Table 4

[0237] Table 5

[0238] Table 6

[0239] Table 7

[0240] Table 8

[0241] Table 9

[0242] From the data reported in Table 1 it can be seen that: the addition of the randomizing agent (e.g., 2-ethoxymethyl)-tetrahydrofuran (THFA-ethyl) before the addition of the lithium-based initiator (e.g., n-butyl lithium) allows to obtain functionalized styrene-butadiene copolymers having low glass transition temperature (Tg) but a low degree of randomization of the styrene units [Example 1 (comparative)] and [Example 2 (comparative)] ; the addition of the randomizing agent (e.g., 2-ethoxymethyl)-tetrahydrofuran (THFA-ethyl) after the addition of the lithium-based initiator (e.g., n-butyl lithium) upon initiated polymerization allows to obtain functionalized styrenebutadiene copolymers having low glass transition temperature (Tg) and high degree of randomization of the styrene units only in case the AT falls within specific ranges [Example 5 (invention)], [Example 6 (invention)], [Example 7 (invention)], [Example 8 (invention)] and [Example 9 (invention)]; the addition of the randomizing agent (e.g., 2-ethoxymethyl)-tetrahydrofuran (THFA-ethyl) after the addition of the lithium-based initiator (e.g., n-butyl lithium) upon initiated polymerization does not allow to obtain functionalized styrene-butadiene copolymers having low glass transition temperature (Tg) and high degree of randomization of the styrene units in case the AT does not fall within specific ranges [Example 3 (comparative)] and [Example 4 (comparative)]. From the data reported in Tables 2-9 it can be seen that the functionalized styrenebutadiene random copolymer subject-matter of the present invention is advantageously usable in silica-based elastomeric compositions usable in the winter tire treads.

Claims

CLAIMS1. Functionalized styrene-butadiene random copolymer having the following characteristics:(i) a glass transition temperature (Tg) comprised between -80°C and -55°C, preferably comprised between -75°C and -60°C;(ii) a content of styrene units comprised between 5% by weight and 25% by weight, preferably comprised between 10% by weight and 20% by weight, more preferably comprised between 13% by weight and 17% by weight, with respect to the total weight of the copolymer;(iii) a content of 1,2-vinyl units comprised between 15% by weight and 50% by weight, preferably comprised between 20% by weight and 40% by weight, more preferably comprised between 30% by weight and 36% by weight, with respect to the total weight of the butadiene units;(iv) a peak average molecular weight (Mp) comprised between 100 kDa and 250 kDa, preferably comprised between 150 kDa and 195 kDa;(v) a polydispersion index (PDI), that is, the ratio between the weight average molecular weight (Mw) and the number average molecular weight (Mn) (Mw / Mn), less than or equal to 1.5, preferably comprised between 1.1 and 1.45;(vi) a Mooney viscosity (MLl+4@ 100°C) comprised between 40 and 120, preferably comprised between 50 and 90, more preferably comprised between 55 and 75;(vii) polystyrene blocks wherein the polymer chains consisting of a chain of at least 16 consecutive styrene units are present in an amount less than or equal to 5% by weight, preferably less than 3% by weight, more preferably less than 1% by weight, with respect to the total weight of the styrene units present in the copolymer.

2. Functionalized styrene-butadiene random copolymer according to claim 1, wherein said functionalized styrene-butadiene random copolymer has a coupling percentage comprised between 10% by weight and 70% by weight, preferably comprised between 12% by weight and 50% by weight, more preferably comprised between 15% by weight and 40% by weight, with respect to the total weight of the copolymer.

3. Functionalized styrene-butadiene random copolymer according to claim 1 or 2, wherein said functionalized styrene-butadiene random copolymer has a percentage of terminal functionalization comprised between 30% by weight and 90% by weight, preferably comprised between 50% by weight and 88% by weight, more preferably comprised between 60% by weight and 85% by weight, with respect to the total weight of the copolymer.

4. Batch process for the preparation of a functionalized styrene-butadiene random copolymer comprising the following sequential steps:(a) copolymerizing, via anionic route, 1,3-butadiene and styrene, in the presence of at least one hydrocarbon solvent and at least one lithium-based initiator and continuing said copolymerization for the time necessary to reach a temperature Ti defined by the following equation:T1 = Trigger + AT wherein:T u-igger is the temperature at which said at least one lithium-based initiator is added and the copolymerization is triggered;AT is comprised between 5°C and 39°C, preferably comprised between10°C and 38°C, more preferably comprised between 13°C and 35°C;(b) adding at least one randomizing agent and continuing the copolymerization until substantially complete conversion of 1,3-butadiene and styrene;(c) optionally, adding at least one coupling agent;(d) adding at least one alkoxy-silane.

5. Batch process for the preparation of a functionalized styrene-butadiene random copolymer according to claim 4, wherein in said step (a) said at least one hydrocarbon solvent is selected from aliphatic, cycloaliphatic or aromatic hydrocarbon solvents such as propane, n-butane, zso-butane, 2-methyl propane, n-pentane, 2-methyl butane, 2- methyl pentane, 3 -methyl pentane, zso-pentane, n- hexane, n- heptane, n-octane, cyclohexane, cyclopentane, methyl-cyclopentane, methyl-cyclohexane, 2,2-dimethyl butane, 2,3-dimethyl butane, 2,2-dimethyl pentane, 2,3,3-trimethyl butane, 3,3-dimethyl pentane, 2,3-dimethyl pentane, 2-methyl hexane, 3-methyl hexane, benzene, toluene, xylene, ethylbenzene, or mixtures thereof; preferably in anhydrous form; preferably from cyclohexane, n-hexane, or mixtures thereof, in anhydrous form.

6. Batch process for the preparation of a functionalized styrene-butadiene random copolymer according to claim 4 or 5, wherein said step (a) is carried out in the presence of:75% by weight - 95% by weight, preferably 80% by weight - 90% by weight, more preferably 83% by weight - 87% by weight, with respect to the total weight of 1,3-butadiene and styrene, of 1,3 -butadiene; and5% by weight - 25% by weight, preferably 10% by weight - 20% by weight, more preferably 13% by weight - 17% by weight, with respect to the total weight of 1,3-butadiene and styrene, of styrene.

7. Batch process for the preparation of a functionalized styrene-butadiene random copolymer according to any one of claims from 4 to 6, wherein in said step (a) said at least one lithium-based initiator is selected from compounds having a general formula (I):Ri-Li (I) wherein Ri represents a C1-C20, preferably C2-C12, linear or branched alkyl group, a C3- C30, preferably C4-C10 cycloalkyl group, a C6-C30, preferably C6-C12 aryl group.

8. Batch process for the preparation of a functionalized styrene-butadiene random copolymer according to claim 7, wherein in said step (a) said at least one lithium-based initiator is selected from: lithium methyl, lithium ethyl, lithium n-butyl, lithium secbutyl, lithium Z-butyl, lithium n-propyl, lithium-2-propyl, lithium zso-butyl, lithium n- pentyl, lithium cyclohexyl, lithium phenyl, lithium 1 -methyl styryl, lithium p-tolyl, lithium naphthyl, L,L-diphenyl-5-lithium-3-methyl-pentyl, or mixtures thereof; preferably it is lithium n-butyl.

9. Batch process for the preparation of a functionalized styrene-butadiene random copolymer according to any one of claims from 4 to 8, wherein in said step (b) said at least one randomizing agent is selected from: non-cyclic ethers such as ethyl ether, or mixtures thereof; tertiary amines such as tri-butyl amine; cyclic ethers such as tetrahydrofuran (THF); chelating ethers such as ethylene glycol dimethyl ether(dimethylglime), dioxane, 2-ethoxymethyl-tetrahydro furan (THFA-ethyl), 2-methoxy ethyl-tetrahydropyran, or mixtures thereof; chelating amines such as N,N,N’,N’- tetramethylethylenediamine (TMEDA); or mixtures thereof; preferably it is selected from tetrahydrofuran (THF), 2-(ethoxymethyl)-tetrahydrofuran (THFA-ethyl), or mixtures thereof; more preferably it is 2-(ethoxymethyl)-tetrahydrofuran (THFA-ethyl).

10. Batch process for the preparation of a functionalized styrene-butadiene random copolymer according to any one of claims from 4 to 9, wherein in said step (c) said at least one coupling agent is selected from organometallic compounds having general formula (II):(R2)mM(X)p (II) wherein R2represents a Ci-C2o, preferably C2-Cs, linear or branched alkyl group, a Ci- C2o, preferably C2-Cs, linear or branched alkenyl group, a C3-C30, preferably C4-C10 cycloalkyl group, a C3-C30, preferably C4-C10 cycloalkenyl group, a C6-C30, preferably C6-Ci2aryl group, M represents a silicon, germanium or tin atom, preferably silicon or tin, X represents a halogen atom such as chlorine, bromine, fluorine, iodine, preferably chlorine, m is an integer comprised between 0 and 2, and p is an integer comprised between 2 and 4.

11. Batch process for the preparation of a functionalized styrene-butadiene random copolymer according to claim 10, wherein in said step (c) said coupling agent is selected from: silicon tetrachloride (SiCU), tin tetrachloride (SnCU), or mixtures thereof; preferably it is tin tetrachloride (SnCU).

12. Batch process for the preparation of a functionalized styrene-butadiene random copolymer according to any one of claims from 4 to 11, wherein in said step (d) said at least one alkoxy-silane is selected from compounds having the general formula (III) or (IV):O-R4R3-O— Si — (R6)— A (III)O-R5O-R4R3- Si — (R6)— A (IV)O-R5wherein:R3, R4 and R5, each independently, represent a C1-C20, preferably C2-C12, linear or branched alkyl group, a C3-C30, preferably C4-C10 cycloalkyl group, a C6-C30, preferably C6-C12 aryl group; preferably they represent methyl, ethyl, propyl, n- butyl, sec-butyl, ter-butyl, octyl;Re represents a C1-C20, preferably C1-C10, linear or branched hydrocarbon chain, optionally containing one or more unsaturations, said unsaturations being optionally present in an amount not exceeding 2, optionally containing heteroatoms selected from oxygen, nitrogen, sulphur, said heteroatoms being optionally present in an amount not exceeding three;A represents a C1-C20, preferably C2-C12, linear or branched alkyl group, a C3-C12, preferably C3-C6 heterocyclic group, containing at least one heteroatom selected from nitrogen, oxygen, sulphur, silicon, selenium, phosphorus, preferably containing one nitrogen atom and one oxygen atom; preferably said heterocyclic group is linked to the Re substituent via a nitrogen atom, even more preferably said heterocyclic group is morpholine.

13. Batch process for the preparation of a functionalized styrene-butadiene random copolymer according to claim 12, wherein in said step (d) said alkoxy-silane is selected from: tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, tetrapentoxysilane tetrahexoxysilane, tetraheptoxysilane, tetraoctoxysilane, triethoxypropoxysilane triethoxybutoxysilane, triethoxypentoxysilane, triethoxyhexoxysilane, triethoxyheptoxysilane, triethoxyoctoxysilane, diethoxypropoxyxysilane, diethoxydibutoxysilane, diethoxydipentoxysilane, diethoxydihexoxysilane, diethoxydieptoxysilane, diethoxydioctoxysilane, triproxyethoxysilane, tripropoxybutoxysilane, tripropoxypentoxysilane, tripropoxyhexoxysilane, tripropoxyheptoxysilane, tripropoxyoctoxysilane, tributoxyethoxysilane, tributoxypropoxysilane, tributoxypentoxysilane, tributoxyhexoxysilane, tributoxyheptoxysilane, tributoxyoctoxysilane, tripentoxyethoxysilane, tripentoxypropoxysilane, tripentoxybutoxysilane, tripentoxyhexoxysilane, tripentoxyhepthoxysilane, tripentoxyoctoxysilane, trihesoxyethoxysilane, trihesoxypropoxysilane, trihesoxybutoxysilane, trihesoxypentoxysilane,trihesoxyheptoxysilane, trihexoxy-octoxysilane, triheptoxyethoxysilane. triheptoxypropoxysilane, triheptoxybutoxysilane, triheptoxypentoxysilane. triheptoxyhexoxysilane, triheptoxyoctoxysilane, trioctoxyethoxysilane. trioctoxypropoxysilane, trioctoxybutoxysilane, trioctoxypentoxysilane. trioctoxyhexoxysilane, trioctoxyeptoxysilane,3-morpholinopropyltrimethoxysilane, 3 -morpholinopropyltriethoxy silane, 3- morpholinopropyltripropoxysilane, 3 -morpholinopropyltributoxy silane, 3 - morpholinopropyltripentoxysilane, 3 -morpholinoprop yltrihexoxysilane, 3 - morpholinopropyltriheptoxysilane, 3 -morpholinopropyltrioctoxy silane, 3 - morpholinopropylmethyldimethoxysilane, 3-morpholinopropylmethyldiethoxysilane.3 -morpholinopropylmethyldipropoxy silane, 3 -morpholinopropylmethyldibutoxy silane, 3 -morpholinopropylmethyldipentoxy silane, 3 -morpholinoprop ylmethyldihexoxy silane, 3 -morpholinopropylmethyldiheptoxy silane, 3 -morpholinoprop ylmethyldioctoxy silane, 3 -morpholinopropylethyldimethoxysilane, 3 -morpholinopropylethyldiethoxysilane, 3 - morpholinoprop ylethyldipropoxysilane, 3 -morpholinopropylethyldibutoxy silane, 3- morpholinopropylethyldipentoxy silane, 3 -morpholinoprop ylethyldihexoxy silane, 3- morpholinopropylethyldiheptoxy silane, 3 -morpholinoprop ylethyldioctoxy silane, 3- morpholinopropylpropyldimethoxysilane, 3 -morpholinopropylpropyldiethoxy silane, 3- morpholinopropylpropyldipropoxy silane, 3 -morpholinopropylpropyldibutoxy silane, 3- morpholinopropylpropyldipentoxysilane, 3 -morpholinopropylpropyldiexoxy silane, 3 - morpholinoprop ylpropyldieptoxysilane, 3 -morpholinoprop ylpropyldioctoxysilane, 3- morpholinopropylbutyldimethoxysilane, 3 -morpholinopropylbutyldiethoxy silane, 3- morpholinopropylbutyldipropoxy silane, 3 -morpholinoprop ylbutyldibutoxysilane, 3- morpholinopropylbutyldipentoxysilane, 3 -morpholinoprop ylbutyldihexoxy silane, 3 - morpholinopropylbutyldiheptoxysilane, 3-morpholinopropylbutyldioctoxysilane,3 -piperidinopropyltrimethoxy silane, 3 -piperidinopropyltriethoxy silane, 3 - piperidinopropylmethyldimethoxy silane, 3 -piperidinopropylethyldimethoxy silane, 3- piperidinopropylmethyldiethoxy silane, 3 -piperidinopropylethyldiethoxy silane, N- 3- trimethoxysilylpropyl)-4,5-dihydro-imidazole, A / -(3-tricthoxysilylpropyl)-4,5-dihydro- imidazole, A / -(3-trimcthoxysilylpropyl)-4,5-imidazolc, A / -(3-tricthoxysilylpropyl)-4,5- imidazole, 3 -hexamethyleneiminopropyltrimethoxy silane, 3 -hexamethyleneimino-propyltriethoxy silane, 3 -hexamethyleneiminoprop ylmethyldimethoxy silane, 3- hexamethyleneiminopropylethyldimethoxysilane, 3 -hexamethyleneiminopropylmethyldiethoxysilane, 3 -hexamethyleneiminopropylethyldiethoxy silane, N-( 1,3- dimethylbutylidene)-3-(triethoxysilyl)-propylamine, or mixtures thereof; preferably from 3 -morpholinopropylmethyldiethoxy silane, 3 -morpholinopropyltriethoxy silane, N- (l,3-dimethyl-butylidene)-3-(triethoxysilyl)propylamine, tetraethoxysilane, or mixtures thereof; more preferably from 3-morpholinopropylmethyldiethoxysilane, 3- morpholinopropyltriethoxysilane.

14. Batch process for the preparation of a functionalized styrene-butadiene random copolymer according to any one of claims from 4 to 13, wherein: said step (a) is carried out at a temperature comprised between 10°C and 70°C, preferably comprised between 30°C and 65°C; said step (a) being in any case carried out at a temperature in which the monomers are kept in liquid form; and / or said step (b) is carried out at a temperature comprised between 35°C and 120°C, preferably comprised between 40°C and 100°C; and / or for a time comprised between 5 minutes and 45 minutes, preferably comprised between 5 minutes and 30 minutes; and / or said step (c) is carried out at a temperature comprised between 75°C and 120°C, preferably comprised between 80°C and 100°C; and / or for a time comprised between 4 minutes and 20 minutes, preferably comprised between 5 minutes and 15 minutes; and / or said step (d) is carried out at a temperature comprised between 75°C and 120°C, preferably comprised between 80°C and 100°C; and / or for a time comprised between 4 minutes and 20 minutes, preferably comprised between 5 minutes and 15 minutes.

15. Elastomeric composition, in particular silica-based elastomeric composition, comprising at least one styrene-butadiene random copolymer according to any one of claims 1 to 14.

16. Use of the elastomeric composition according to claim 15, for the production of winter and all-season tires, in particular tire treads.

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