Elastomeric compounds and related summer tyres for vehicle wheels

Abstract

The present invention relates to tyre elastomeric compositions and compounds, to tyres for vehicle wheels comprising them which are particularly performant and advantageous for summer use. The tyres of the invention, comprising such compounds especially in the tread band, are characterized by reduced wear and rolling resistance and high grip, both under wet and dry conditions. These advantageous features are obtained by combining certain conjugated diene polymers with a plasticizing admixture with a predetermined content of resins and oils.

Description

[0001] ELASTOMERIC COMPOUNDS AND RELATED SUMMER TYRES FOR VEHICLE WHEELS DESCRIPTION

[0002] The present invention relates to tyre elastomeric compositions and related tyre elastomeric compounds, to tyres for vehicle wheels which comprise them which are particularly performant and advantageous for summer use.

[0003] The summer tyres of the invention comprising such compounds, especially in the tread band, are characterized by reduced wear and rolling resistance and high grip, both under wet and dry conditions. These advantageous features are obtained by combining certain conjugated diene polymers with a plasticizing admixture with a predetermined content of resins and oils.

[0004] BACKGROUND

[0005] In the tyre sector, car manufacturers are demanding ever-higher performances. For eco-sustainability, cost-effectiveness and safety reasons, it is desirable to reduce tyre wear in order to extend tyre life, to minimize environmental pollution and to maintain tyre grip over time, grip that is negatively affected by tread wear thus typically resulting in a worsening of traction and breaking performance.

[0006] Within the vehicle tyre offering, summer tyres are optimized for hot weather and for driving temperatures typically above 7 °C. Typically, summer tyres have large tread blocks and few sipes, thus increasing the amount of rubber in contact with the road and consequently improving handling and braking. Furthermore, they usually have a shallower tread depth compared to winter tyres as they do not need the same grip on the road as winter tyres would on snow.

[0007] An important requirement of summer tyres is good handling in both, wet and dry conditions. This can be achieved partly with the specially designed tyre tread pattern and partly with tailored elastomeric compounds. The elastomeric compounds for summer tyres need to maximize safety and driving comfort in warm months. Heat always softens tyre rubber compounds so generally they are designed harder than those of other tyre types. However, they should remain soft enough to maintain driving comfort without excessively increasing tyre friction and fuel consumption.

[0008] Typically, the elastomeric compounds used in the manufacture of the tread band of summer tyres comprise mixtures of high Tg polymers (e.g. Tg above -50 °C) such as random styrene butadiene rubbers (SBR), optionally blended with other polymers, such as polybutadiene rubber (BR), and / or natural rubber (NR), in combination with plasticisers, such as process oils and resins. Polybutadiene rubbers (BR) are appreciated for their mechanical properties of high resistance to abrasion. Solution-polymerised functionalized random styrene butadiene SBR rubbers (S-SBR), such as TUFDENE E680, are commonly used to improve handling performance especially under wet conditions, while higher molecular weight emulsion-polymerised functionalized random SBR rubbers (E-SBR), such as SBR 1739, provide for high tear strength.

[0009] To give the summer tyre high resistance to tearing and abrasion and therefore a long road life, blends of emulsion random styrene-butadiene copolymer (E-SBR) and polybutadiene (BR) may be used in the tread band compounds but at the expense of wet road performance. On the other hand, by replacing the emulsion styrene butadiene rubber (E-SBR) and part of the polybutadiene rubber (BR) with a conventional solution-polymerised random styrene butadiene rubber (S-SBR) with the aim to improve handling under wet conditions, a decrease in the mechanical resistance is observed.

[0010] In other words, in summer tyre compounds it seems quite difficult to reconcile opposed requirements of wear resistance, grip under wet and dry conditions and friction, with the aforesaid conventional polymers.

[0011] According to the Applicant, there is still room for improvement of the physical properties of the known rubber compositions for summer applications in terms of wear resistance, rolling resistance and grip on both wet and dry roads.

[0012] SUMMARY OF THE INVENTION

[0013] The Applicant has carried out studies with the aim to provide elastomeric compounds for tyres with improved performance for summer applications, in particular with a better grip both on wet and dry surfaces, reduced tread abrasion and lower rolling resistance.

[0014] The Applicant has surprisingly found that by compounding particular conjugated diene polymers, characterized by peculiar segmented microstructures and by Tg DSC values typical of winter applications, preferably as main or sole elastomeric polymers of the compound, with a tuned plasticizer composition, it is possible to provide tyre elastomeric compounds advantageous for summer applications that show grip improvement, both on dry and wet surfaces, a significantly reduced wear and low rolling resistance. The increased wear resistance, without impairing other important properties of the elastomeric compound, is predictive of performance retention over time and longer tyre life.

[0015] Accordingly, a first object of the present invention is an elastomeric composition comprising: - 100 phr of one or more elastomeric polymers comprising one or more conjugated diene polymer (I), said conjugated diene polymer (I) comprising bound conjugated diene monomer units (Y) and, optionally, bound aromatic vinyl monomer units (X) and including at least a first polymer segment and at least a second polymer segment, wherein: Y1 (mol %) is the amount of vinyl unit in the bound conjugated diene monomer unit of the first polymer segment,

[0016] Y2 (mol %) is the amount of vinyl unit in the bound conjugated diene monomer unit of the second polymer segment,

[0017] X1 (wt %) is the amount of bound aromatic vinyl monomer unit in the first polymer segment, X2 (wt %) is the amount of bound aromatic vinyl monomer unit in the second polymer segment, wherein said conjugated diene polymer (I) has a Tg DSC measured according to the method of ISO 22768:2006, modified with a heating rate of 10 °C / min, not higher than -40 °C, preferably not higher than -50 °C;

[0018] - 20 phr to 80 phr of a plasticizing admixture comprising:

[0019] 15 phr to 50 phr of at least a solid resin

[0020] 5 phr to 50 phr of at least a liquid resin

[0021] 0 phr to 25 phr of at least an oil

[0022] 0 phr to 30 phr of at least a liquid polymer;

[0023] - 10 phr to 150 phr of at least a reinforcing filler; and

[0024] - at least 0.5 phr of at least a vulcanizing agent.

[0025] Preferably, in said conjugated diene polymer (I), X1 is different from X2 and / or Y1 is different from Y2.

[0026] Preferably, in said conjugated diene polymer (I) the absolute difference between Tg DSC end temperature and Tg DSC onset temperature is lower than 35 °C, than 30 °C, than 20 °C or than 15 °C and / or higher than 10 °C or than 12 °C or than 13 °C.

[0027] A further object of the present invention is an elastomeric compound obtainable from the elastomeric composition of the invention, the elastomeric compound preferably having after vulcanization a glass transition temperature Tg, measured by dynamo-mechanical analysis (DMA), from -35 °C to -15 °C.

[0028] A further object of the present invention is a tyre for vehicle wheel, preferably a summer tyre, comprising the elastomeric compound of the invention, preferably at least in the tread band.

[0029] DEFINITIONS

[0030] For the purposes of the present description and the following claims, the term "phr" (acronym for parts per hundreds of rubber) indicates the parts by weight of a given elastomeric compound component per 100 parts by weight of the elastomeric polymer, considered net of any plasticizing extension oil.

[0031] Unless otherwise indicated, all the percentages are percentages by weight. The term “elastomeric composition” refers to a composition, comprising at least one diene elastomer polymer and one or more additives, which by mixing provides an elastomeric compound suitable for use in tyre components.

[0032] The components of the elastomeric composition generally are not introduced simultaneously into the mixer but typically added sequentially. In particular, vulcanizing additives, such as the vulcanizing agent and optionally accelerators and retarders, are usually added at a stage downstream from the incorporation and processing of all other components. In the intermediate or final elastomeric compound, the individual components of the elastomeric composition do not always remain unaltered or individually traceable, as they may have been transformed, in whole or in part, by interaction with other components, heat and / or mechanical processing. The term “elastomeric composition” herein is intended to include the totality of all components that are added in the preparation of the elastomeric compound, irrespective of whether they are all actually present simultaneously, whether they are introduced sequentially, or whether they are subsequently traceable in the final elastomeric compound or tyre.

[0033] The term “cross-linkable elastomeric composition” refers to an elastomeric composition comprising at least an elastomeric diene polymer(s), a reinforcing filler and a vulcanizing agent.

[0034] The term "elastomeric compound" means the mixture obtainable by mixing and preferably heating, at specific pressure and temperature conditions, at least one elastomeric diene polymer with at least one of the additives commonly used in the preparation of compounds for tyres.

[0035] The term “vulcanized or cross-linked elastomeric compound” means the material obtainable by cross-linking or sulfur-curing an elastomeric compound.

[0036] The term “conjugated diene polymer” refers to a polymer or copolymer derived from the polymerization of one or more monomers, at least one of which is a conjugated diene (conjugated diolefin).

[0037] The term " elastomeric polymer" or “elastomeric diene polymer” means a natural or synthetic polymer which, after vulcanization, can be repeatedly stretched at room temperature to at least twice its original length and after removal of the tensile load returns substantially immediately and forcefully to its approximate original length (as defined in ASTM D1566-11 Standard terminology relating to Rubber).

[0038] The term "vulcanization" refers to the cross-linking reaction in a natural or synthetic rubber induced for example by a sulfur-based vulcanizing agent.

[0039] The term “raw or green” refers to a material, compound, component or tyre that has not yet been vulcanized. The term “vulcanizing agent” refers to a cross-linking agent capable of transforming natural or synthetic rubber into an elastic and resistant material through the formation of a three-dimensional network of inter- and intra-molecular cross-links.

[0040] The term “vulcanization accelerator” refers to a chemical agent capable of decreasing the duration of the vulcanization process and / or operating temperature, such as TBBS, sulphenamides in general, thiazoles, dithiophosphates, dithiocarbamates, guanidines, as well as sulfur donors such as thiurams.

[0041] The term “vulcanizing activator” refers to a chemical agent that can further facilitate curing, causing it to take place at a shorter time and optionally lower temperature. An example of an activator is the stearic acid-zinc oxide system.

[0042] The term “vulcanizing retardant” refers to a chemical agent capable of delaying the start of the curing reaction and / or suppressing undesirable secondary reactions, e.g. N-(cyclohexylthio) phthalimide (CTP).

[0043] The term “curing system” refers to a system of chemical agents comprising at least one vulcanizing agent and optionally an accelerator agent, a retardant agent and a vulcanization activating agent,

[0044] The term "reinforcing filler" refers to a reinforcing material typically used in the industry to improve the mechanical properties of tyre(s), chosen preferably from carbon black, conventional silica, such as sand silica precipitated with strong acids, preferably amorphous, diatomaceous earth, calcium carbonate, titanium dioxide, talc, alumina, aluminosilicates, kaolin, silicate fibres and mixtures thereof.

[0045] The term “white filler” refers to a conventional reinforcing material used in the industry chosen from conventional silica and silicates, such as sepiolite, palygorskite (also known as attapulgite), montmorillonite, halloysite and the like, optionally modified by acid treatment and / or derivatization. Typically, white fillers have surface hydroxyl groups.

[0046] The term "mixing phase 1" refers to the step in the elastomer compound preparation process in which one or more additives may be incorporated by mixing and optionally heating, at specific pressure and temperature conditions, except for the vulcanizer which is fed in phase 2. The mixing phase 1 is also called the “non-production phase”. In the preparation of a compound, there may be several "non-productive" mixing phases which may be referred to as 1 a, 1 b, etc.

[0047] The term "mixing phase 2" refers to the next step in the elastomeric compound preparation process in which the vulcanizing agent and, optionally, the other additives of the vulcanization package are introduced into the elastomeric compound obtained from phase 1, and mixed into the material, at a controlled temperature, generally at a compound temperature of less than 120 °C, so as to provide the vulcanizable elastomeric compound. The mixing phase 2 is also referred to as the “production phase”. Each mixing phase may comprise several intermediate phases or sub-phases of processing, characterized by the momentary interruption of mixing to allow the addition of one or more ingredients but without intermediate dumping of the compound.

[0048] The term "modification" or "functionalization" refers to a chain-end modification reaction between one end of a single polymer chain and one or more modifying agents.

[0049] The term “coupling” or “branching” reaction corresponds to a chain end reaction between two and, respectively, more than two single polymer chain ends and one or more coupling agents. The chain-end modification reaction between more than two single polymer chain ends and a coupling agent results in polymers comprising three or more arms at the coupling point.

[0050] In the present description, coupling functions and modifying functions may be present in the same agent that thus acts as coupling as well as modifying agent, the coupling functions providing the branching and the modifying functions modifying the properties of the polymer, for instance by making it more compatible with the filler and thus allowing the filler to be better distributed in the compound.

[0051] The term “modification rate” refers to the weight content ratio, expressed in %, of the modified conjugated diene polymer component having a modifying functional group in the polymer relative to the total amount of the conjugated diene polymer mixture.

[0052] The term “degree of branching” refers to the number of polymer arms / chains at the coupling point.

[0053] A “random” (or statistical) polymer, as defined here, includes two or more types of monomers that are polymerized in a non-regularor non-coherent manner, i.e. the sequence of monomers within the polymer chain follows a statistical rule.

[0054] A “block copolymer”, as defined herein, essentially consists of two types of monomers that are polymerized in a regular or coherent manner, thus forming two or more homopolymer subunits that are connected by covalent bonds.

[0055] The term “microstructure” herein refers to the composition of a conjugated diene polymer composed of conjugated diene units and, optionally, of aromatic vinyl units.

[0056] The term “segmented microstructure” herein refers to the microstructure of a conjugated diene polymer that comprises at least two different segments linked by a covalent bond or by a coupling agent, said segments having a different distribution of conjugated diene units and, optionally, of aromatic vinyl units and consequently different Tg.

[0057] The term “segment or polymer segment” herein refers to a portion of the conjugated diene polymer (I) including conjugated diene monomer units and aromatic vinyl monomer units or conjugated diene monomer units only. The term “polymer segment ratio in the conjugated diene polymer (I)” means the average weight fraction or, if so indicated, percentage of each polymer segment relative to the entire conjugated diene polymer (I).

[0058] The term “bound conjugated diene” herein refers to the conjugated diene monomer unit which is incorporated into the conjugated diene polymer (I) by polymerization.

[0059] The term "amount of bound aromatic vinyl monomer unit" herein refers to the wt % of bound aromatic vinyl monomer units with respect to a segment weight or the conjugated diene polymer (I) weight.

[0060] The term "amount of vinyl unit" herein refers to the value of the molar fraction (mol %) of 1 , 2-vinyl units with respect to the bound conjugated diene monomer units contained in the conjugated diene polymer (I) (Yall) or in a segment thereof (Y1 , Y2).

[0061] The term “total amount of bound aromatic vinyl unit (Xal I)” herein refers to the weight fraction (wt %) of the bound aromatic vinyl unit relative to the total weight of the conjugated diene polymer (I).

[0062] The term “total amount of vinyl unit (Yall)” herein refers to the mole fraction (mol %) of the 1, 2-vinyl units of the bound conjugated diene in the conjugated diene polymer (I).

[0063] The term “broad Tg” polymer herein refers to a conjugated diene polymer preferably having an absolute difference Tg DSC end - Tg DSC onset of at least 10°C (ISO 22768:2006 modified with a heating rate of 10 °C / min).

[0064] The term “sharp Tg” polymer herein refers to a conjugated diene polymer preferably having an absolute difference T g DSC end - Tg DSC onset lower than 10°C (ISO 22768:2006 modified with a heating rate of 10 °C / min).

[0065] The term “consisting essentially of” means that additional specific components may be present, i.e. those that do not materially influence the essential characteristics of the polymer compound or elastomer composition in question.

[0066] BRIEF DESCRIPTION OF THE FIGURES

[0067] With reference to the accompanying Figures:

[0068] - Figure 1 schematically shows a semi-sectional view of a tyre for vehicle wheels according to the present invention.

[0069] - Figure 2 illustrates the extrapolation of the Tg DSC onset and end temperatures from the DSC thermogram of an exemplary polymer.

[0070] - Figure 3 shows the Tan D plots vs temperature of the compounds of Example 5 (key: continuous line Ex. 2A, reference; mixed point and hatch line Ex. 4A, inventive).

[0071] - Figure 4 shows bar plots of grip at +10 °C (WG for wet grip) 4A, at +23 °C (DG for dry grip) 4B and of rolling resistance (RR) 4C of the compounds of Ex. 1A, 1B and 1C. - Figure 5 shows a radar chart of grip at temperatures of +10 °C (WG for wet grip) and +23 °C (DG for dry grip), of rolling resistance (RR) and of wear (WR) (key: continuous line Ex.

[0072] 2A comparison; mixed point and hatch line Ex. 2B inventive).

[0073] - Figure 6 shows bar plots of grip at +10 °C (WG for wet grip) 6A, grip at +23 °C (DG for dry grip) 6B and of rolling resistance (RR) 60 of the compounds of Ex. 2A (reference), 2B to 2F (inventive).

[0074] - Figure 7 shows bar plots of grip at +10 °C (WG for wet grip) 7A, grip at +23 °C (DG for dry grip) 7B and of rolling resistance (RR) 70 of the compounds of Ex. 3A (comparison) and 3B (inventive).

[0075] - Figure 8 shows bar plots of grip at +10 °C (WG for wet grip) 8A, grip at +23 °C (DG for dry grip) 8B and of rolling resistance (RR) 80 of the compounds of Ex. 4A, 4B and 40 (inventive).

[0076] DETAILED DESCRIPTION OF THE INVENTION

[0077] The elastomeric compositions and the corresponding compounds may have one or more of the following preferred characteristics, taken in isolation or in any desired combination with each other.

[0078] Numerical ranges described as preferable ranges may be replaced with numerical ranges obtained by arbitrarily combining each value described as the upper limit and each value described as the lower limit, even when the combination is not specifically mentioned. The elastomeric composition of the present invention comprises 100 phr of one or more elastomeric polymers comprising one or more conjugated diene polymer (I).

[0079] In the elastomeric composition the one or more conjugated diene polymer(s) (I) is present in total amount preferably of at least 25 phr, 30 phr, 40 phr, 50 phr or 60 phr, more preferably of at least 70 phr, 75 phr or 80 phr, even more preferably of at least 90 phr, still more preferably of at least 95 phr. Most preferably, the one or more conjugated diene polymer(s) (I) is the only elastomeric polymer of the elastomeric composition. The present elastomeric composition shows an improved wear resistance especially when conjugated diene polymer(s) (I) are the only elastomeric polymers.

[0080] The conjugated diene polymer (I) comprises bound conjugated diene monomer units (Y) and, optionally, bound aromatic vinyl monomer units (X).

[0081] Examples of conjugated diene monomer units include, but are not limited to, 1 ,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, 1,3-hexadiene, 1,3-heptadiene and mixtures thereof. Among them, 1,3-butadiene and isoprene are preferred. Examples of aromatic vinyl monomer units include, but are not limited to, styrene, p-methylstyrene, a-methylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, diphenylethylene and mixtures thereof. Among them, styrene is preferred.

[0082] Preferably the conjugated diene polymer (I) comprises 1,3-butadiene and / or isoprene as bound conjugated diene monomer units (Y) and, if present, styrene as bound aromatic vinyl monomer units (X).

[0083] The total amount of aromatic vinyl unit Xall (wt %) and of vinyl unit Yall (mol %) in the conjugated diene polymer (I) can be determined, for instance, by NMR according to the method of ISO 21561-1:2015.

[0084] If the conjugated diene polymer (I) is a polymer of butadiene and styrene, the amount of vinyl unit in the bound butadiene can be calculated by the method of Hampton (R.R. Hampton, Analytical Chemistry, 21, 923 (1949)).

[0085] The conjugated diene polymer (I) comprises at least a first polymer segment and at least a second polymer segment. The first and second polymer segments in the conjugated diene polymer (I) differ from each other in their microstructure. Each polymer segment may differ, for example, in the amount of bound aromatic vinyl unit and / or in the amount of vinyl unit of the bound conjugated diene, namely in the conjugated diene polymer (I) X1 may be different from X2 and / or Y1 may be different from Y2.

[0086] In the conjugated diene polymer (I) the polymer segment ratio (% ratio of the total weight of the first and second polymer segments to the total weight of the conjugated diene polymer (I)) is preferably higher than 70 %, more preferably higher than 80 % and even more preferably higher than 90 %.

[0087] In the conjugated diene polymer (I), preferably X1 is different from X2 and / or Y1 is different from Y2. In the conjugated diene polymer (I) more preferably:

[0088] Y2 -Y1 (mol %) is from 15% to 50% and, if bound aromatic vinyl monomer units are present, |X1 - X2| (wt %) is at most 5% (in the following the first class of the conjugated diene polymer (I)); or

[0089] Y2 -Y1 (mol %) is from 0 mol % to 45 mol % and X2 - X1 (wt %) is higher than 5 wt% (in the following the second class of the conjugated diene polymer (I)).

[0090] In a first class of the conjugated diene polymer (I), the difference Y2 -Y1 (mol %) between the amount of vinyl monomer unit in the second polymer segment Y2 (mol %) and the amount of vinyl monomer unit in the first polymer segment Y1 (mol %) is from 15% to 50%, preferably from 20 mol % to 45 mol %, more preferably from 25 mol % to 45 mol %.

[0091] In the first class, if bound aromatic vinyl monomer units are present, the absolute value of the difference |X1 - X2| (wt %) between the amount of bound aromatic vinyl monomer unit in the second polymer segment X2 (wt %) and the amount of bound aromatic vinyl monomer unit in the first polymer segment X1 (wt %) is preferably at most 5% (wt %) and at least 2 wt %.

[0092] In the first class, preferably the conjugated diene polymer (I) comprises bound aromatic vinyl monomer units. Preferably the bound aromatic vinyl monomer units are present in both the polymer segments (i.e. X1>0 wt % and X2>0 wt %).

[0093] In the first class, the amount of vinyl unit Y1 (mol %) in the first polymer segment is preferably at least 14 mol %, more preferably at least 16 mol %, and even more preferably at least 17 mol % and preferably at most 40 mol %, more preferably at most 35 mol %, even more preferably at most 30 mol %, still more preferably at most 25 mol %.

[0094] In the first class, the amount of vinyl unit Y2 (mol %) in the second polymer segment is preferably at least 40 mol %, more preferably at least 45 mol %, even more preferably at least 50 mol %, still more preferably at least 55 mol % and preferably at most 65 mol %, more preferably at most 62 mol %, and even more preferably at most 61 mol %.

[0095] In the first class, if bound aromatic vinyl monomer units are present, their amount in the first polymer segment X1 (wt %) and in the second polymer segment X2 (wt %) is preferably at least 5 wt %, more preferably at least 7 wt %, even more preferably at least 9 wt % and preferably at most 30 wt %, more preferably at most 25 wt % and even more preferably at most 23 wt % to the weight of the respective polymer segment.

[0096] In the first class, preferably the conjugated diene polymer (I) comprises bound 1,3-butadiene units and bound styrene units in both the at least two polymer segments.

[0097] In the first class, the conjugated diene polymer (I) is preferably characterized by a ratio R = r1 / r2 from 0.25 to 4.00, more preferably from 1.00 to 3.00, even more preferably from 1.50 to 2.40, wherein r1 is the weight ratio of the first polymer segment and r2 is the weight ratio of the second polymer segment to the total weight of the conjugated diene polymer (I). In the first class, the conjugated diene polymer (I) comprises segments with higher content of vinyl units, herein named the second polymer segment, and segments with lower content of vinyl units, herein named the first polymer segment - the first and second polymer segments preferably having the same content of aromatic vinyl units, when present.

[0098] In a second class of the conjugated diene polymer (I), the conjugated diene polymer (I) comprises bound conjugated diene units (Y) and bound aromatic vinyl units (X), preferably it comprises 1 ,3-butadiene and / or isoprene as conjugated diene units and styrene aromatic vinyl units.

[0099] In the second class, the difference Y2 -Y1 (mol %) between the amount of vinyl monomer unit in the second polymer segment Y2 (mol %) and the amount of vinyl monomer unit in the first polymer segment Y1 (mol %) is from 0 mol % to 45 mol %, preferably from 5 mol % to 35 mol %, more preferably from 5 mol % to 20 mol %. In the second class, the difference X2 - X1 (wt %) between the amount of bound aromatic vinyl monomer unit in the second polymer segment X2 (wt %) and the amount of bound aromatic vinyl monomer unit in the first polymer segment X1 (wt %) is higher than 5 wt %, preferably is between 5 wt % and 35 wt %, more preferably between 10 wt % and 30 wt %. In the second class, the amount of vinyl unit Y1 (mol %) in the first polymer segment is preferably from 10 mol % to 50 mol %, more preferably from 12 mol % to 45 mol %, even more preferably from 20 mol % to 40 mol %.

[0100] In the second class, the amount of the aromatic vinyl monomer unit X1 (wt %) in the first polymer segment is preferably at most 10 wt %, more preferably at most 5 wt %, even more preferably in the first polymer segment the aromatic vinyl monomer unit is not present (X1 = 0).

[0101] In the second class, the amount of vinyl unit Y2 (mol %) in the second polymer segment is preferably at least 25 mol % and at most 65 mol %, more preferably at least 40 mol % and at most 60 mol %.

[0102] In the second class, the amount of the aromatic vinyl monomer unit X2 (wt %) in the second polymer segment, is preferably at least 10 wt % and at most 40 wt %, more preferably at least 20 wt % and at most 30 wt %.

[0103] In the second class, the first polymer segment preferably does not comprise any aromatic vinyl monomer unit (X1=0) while the second polymer segment comprises at least an aromatic vinyl monomer unit (X2>0).

[0104] In the second class, the conjugated diene polymer (I) comprises segments with higher content of aromatic vinyl units, herein named second polymer segment, and segments with lower content of aromatic vinyl units, herein named first polymer segment.

[0105] In the second class, the weight ratio (r1) of the first polymer segment to the total weight of the conjugated diene polymer (I) is at least 30 wt % and at most 80 wt %, preferably at least 40 wt % and at most 75 wt %, more preferably at least 50 wt % and at most 70 wt %. In the second class, the weight ratio (r2) of the second polymer segment to the total weight of the conjugated diene polymer (I) is at least 20 wt % and at most 60 wt %, preferably at least 25 wt % and at most 55 wt %, more preferably at least 30 wt % and at most 50 wt %. Preferably, the weight average molecular weight (Mw) of the conjugated diene polymer (I) measured by gel permeation chromatography (GPC) is from 300,000 g / mol to 1,350,000 g / mol, preferably from 400,000 g / mol to 1,000,000 g / mol, more preferably from 400,000 g / mol to 700,000 g / mol.

[0106] The number average molecular weight (Mn) of the conjugated diene polymer (I) measured by gel permeation chromatography (GPC) is preferably at least 100,000 or 170,000 g / mol, more preferably at least 190,000 g / mol and even more preferably at least 200,000 g / mol and / or preferably at most 1,000,000 or 800,000 g / mol, more preferably at most 500,000 g / mol, and even more preferably at most 450,000 g / mol.

[0107] The conjugated diene polymer (I) preferably has a polydispersity index Mw / Mn of at least 1.2 and at most 2.5. Preferably the polydispersity index Mw / Mn is at least 1.3, more preferably at least 1.4 and / or at most 2.4, more preferably at most 2.2, even more preferably at most 2.0.

[0108] In the conjugated diene polymer (I), the polymer segments may be directly bound to each other or may be bound via a coupling agent. The coupling agent preferably comprises a modifying agent e.g. a coupling agent preferably comprises a nitrogen atom-containing group, such as amino alkoxysilanes.

[0109] The conjugated diene polymer (I) preferably comprises a nitrogen containing modifying group and preferably has a modification rate of at least 60%, more preferably at least 65%, even more preferably at least 70%. The modification rate can be measured by chromatography, which can separate modified and non-modified components.

[0110] Suitable modifying agents are alkoxysilane agents having at least a nitrogen atomcontaining group, such as for instance, tris(3-trimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyljamine, tris(3-tripropoxysilylpropyl)amine, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (also referred to as "N,N,N’,N’-tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine"), tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-methyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, bis(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1 ,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1 ,3-bisaminomethylcyclohexane, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tetrakis(3-trimethoxysilylpropyl)-1 ,6-hexamethylenediamine, pentakis(3-trimethoxysilylpropyl)-diethylenetriamine, tris(3-trimethoxysilylpropyl)-methyl-1,3-propanediamine, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, bis(3-trimethoxysilylpropyl)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyljsilane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]silane, 3-tris[2-(2,2-dimethoxy-1-aza-2-silacyclopentane)ethoxy]silyl-1 -trimethoxysilylpropane, 1-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-3,4,5-tris(3-trimethoxysilylpropyl)-cyclohexane, 1-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-3,4,5-tris(3- trimethoxysilylpropyl)-cyclohexane, 3,4,5-tris(3-trimethoxysilylpropyl)-cyclohexyl-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]ether, and (3-trimethoxysilylpropyl)phosphate. Also included are bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]phosphate, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)phosphate, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]phosphate, N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, N-(1 ,3-dimethylbutylidene)-3-(trimethoxysilyl)-1-propanamine, N-benzylidene-3-(triethoxysilyl)propane-1 -amine, N-benzylidene-3-(trimethoxysilyl)propane-1-amine, 1,1-(1,4-phenylene)bis(N-(3(triethoxysilyl)propyl)methanamine), 1,1-(1,4-phenylene)bis(N-(3(trimethoxysilyl)propyl)methanamine), 2-methoxy-2-methyl-1-(benzylideneaminoethyl)-1-aza-2-silacyclopentane, and 2-methoxy-2-methyl-1-(4-methoxybenzylideneaminoethyl)-1-aza-2-silacyclopentane.

[0111] Further included are 1-methyl-4-[3-(trimethoxysilyl)propyl]piperazine, 1-methyl-4-[3-(triethoxysilyl)propyl]piperazine, 1-methyl-4-[3-(methyldimethoxysilyl)propyl]piperazine, 3,3’-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-dimethylpropane-1-amine), 3,3’-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-dimethylpropane-1-amine), 3,3’-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-dimethylpropane-1-amine), 3,3’-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-diethylpropane-1 -amine), 3,3’-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-dipropylpropane-1 -amine), 3,3’-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-diethylpropane-1-amine), 3,3’-(1 , 1 ,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-diethylpropane-1 -amine), and 3,3’-(1 , 1 ,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-dipropylpropane-1-amine).

[0112] Furthermore, also included are 3,3’-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-dipropylpropane-1 -amine), 3,3’-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-diethylmethane-1 -amine), 3,3’-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-diethylmethane-1 -amine), 3,3’-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-diethylmethane-1 -amine), 3,3’-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-dimethylmethane-1-amine), 3,3’-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-dipropylmethane-1 -amine), 3,3’-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-dimethylmethane-1-amine), 3,3’-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-dipropylmethane-1 -amine), 3,3’-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-dimethylmethane-1-amine), 3,3’-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-dipropylmethane-1 -amine), 1 ,3-bis(3-( 1 H-imidazol-1-yl)propyl)-1 , 1 ,3,3-tetramethoxydisiloxane, 1 , 3- bis(3-( 1 H-imidazol-1 -y I) propyl)- 1 , 1 ,3,3-tetraethoxydisiloxane, and 1 , 3-bis(3-( 1 H-imidazol-1 -y I) propyl)- 1 , 1 ,3,3-tetrapropoxydisiloxane. The obtained degree of branching depends on the type of coupling agent used. Preferably, the degree of branching of the conjugated diene polymer (I) is greater than 2.

[0113] Suitable coupling and / or modifying agents, herein incorporated by reference, are disclosed for instance in the patent application JP2023-072838.

[0114] The conjugated diene polymer (I) can be manufactured according to conventional polymerization techniques, for instance as described in JP2023-072838 or in WO2018128285A1.

[0115] Notwithstanding the summer applications, the conjugated diene polymer (I) is characterized by a DSC glass transition temperature (Tg DSC) typical of winter applications. Typically, the conjugated diene polymer (I) has only one Tg DSC.

[0116] Preferably, the Tg DSC of the conjugated diene polymer (I) is from -80 °C to -50 °C, more preferably from -75 °C to -50 °C, even more preferably from -65 °C to -55 °C, measured according to the method of ISO 22768:2006, modified with a heating rate of 10 °C / min. The glass transition temperature of the conjugated diene polymer (I) can be controlled within the numerical range described above by adjusting the total amount of bound aromatic vinyl monomer unit Xall (wt %) and the total amount of vinyl unit Yall (mol %) in the conjugated diene polymer (I).

[0117] Furthermore, the conjugated diene polymer (I) is characterized by a particularly flattened Tg curve, contrary to the sharp Tg curve of conventional SBRs. In the conjugated diene polymer (I) comprising the at least two polymer segments, the greater the difference in the Tg of the two polymer segments, the wider the DSC glass transition peak.

[0118] The broadness of the Tg DSC peak of the conjugated diene polymer (I) can be expressed as absolute difference between the extrapolated Tg DSC end temperature and Tg DSC onset temperature.

[0119] The absolute difference between the extrapolated Tg DSC end temperature and the extrapolated Tg DSC onset temperature of the conjugated diene polymer (I) is preferably lower than 35 °C, lower than 30 °C, lower than 20 °C or lower than 15 °C. Preferably said difference is higher than 10 °C, more preferably higher than 12 °C or than 13 °C.

[0120] Preferably the absolute difference between Tg DSC end temperature and Tg DSC onset temperature is between 10 °C and 35 °C, more preferably between 12 °C and 20 °C, even more preferably between 13 °C and 16 °C.

[0121] The Tg peak value, Tg end temperature and the Tg onset temperature of the conjugated diene polymer (I) can be extrapolated from the DSC thermogram, measured according to the method of ISO 22768:2006, modified with a heating rate of 10 °C / min, as illustrated in Figure 2. The peculiar thermal behaviour of the conjugated diene polymer (I), namely the broad Tg peak, is due to the presence in the polymer chains of alternating segments of different composition, in particular having a diverse content of aliphatic and, possibly, aromatic vinyls, resulting in different segment Tg. In other words, the conjugated diene polymer (I), comprising two or more polymer segments, undergoes glass transition in a plurality of temperature ranges as the polymer segments have different glass transition temperatures. The International Patent applications PCT / EP2024 / 061518 and PCT / EP2024 / 061544 in the name of the Applicant, herein incorporated by reference, disclose this type of polymers. In particular, those applications describe conjugated diene polymers (I) characterized by Tg DSC peak values ranging approximately from -75 °C to -20 °C and by flattened Tg peaks due to the presence of alternating segments in the polymer chains having different Tg values. Those segments in the conjugated diene polymer (I) of the first patent application have a similar aromatic vinyl content and a quite diverse aliphatic vinyl content while vice versa in the segments of the conjugated diene polymer (I) of the second patent application.

[0122] Specific examples of conjugated diene polymer (I) of the first class suitable for the present elastomeric composition are the polymers P1 , P2, P3, P4 and, in particular, P5 (herein PV1 , PV2, PV3, PV4 and PV5 respectively) described in the experimental part of the International Patent application PCT / EP2024 / 061518, having a Tg DSC ranging from -65 °C to -53 °C and an absolute difference between Tg DSC end temperature and Tg DSC onset temperature ranging from 12 to 14 °C (see Table 1 of the present description).

[0123] Specific examples of conjugated diene polymer (I) of the second class suitable for the present elastomeric composition are the polymers P2, P3, P4 and, in particular, P1 (herein PS2, PS3, PS4 and PS1) described in the experimental part of the International Patent applications PCT / EP2024 / 061544, having a Tg DSC ranging from -74 °C to -60 °C and an absolute difference between Tg DSC end temperature and Tg DSC onset temperature ranging from 14 to 34 °C (see Table 1 of the present description).

[0124] Suitable conjugated diene polymers (I) are also disclosed in the patent applications JP2023-072878 and JP2023-072838, herein incorporated by reference.

[0125] In the present elastomeric composition, the complement to the conjugated diene polymer(s) (I) up to 100 phr can be one or more conventional elastomeric polymer(s), as described below.

[0126] Preferably, the one or more conventional elastomeric polymer(s) are present in total amount of at most 75 phr, 70 phr, 60 phr, 50 phr or 40 phr, more preferably of at most 30 phr, 20 phr or 10 phr, even more preferably of at most 5 phr, still more preferably they are not present at all. The elastomeric polymer(s) may be selected from those commonly used in sulfur-vulcanizable elastomeric compositions, which are particularly suitable for producing tyres, i.e. from among solid elastomeric polymers or copolymers with an unsaturated chain having a glass transition temperature (Tg) generally lower than 20 °C, preferably in the range from 0 °C to -110 °C.

[0127] Typically, conventional elastomeric polymers as herein meant do not contain segments of different composition and different Tg within the polymer chains and do not show broad DSC Tg curves, e.g. with an absolute difference between Tg DSC end temperature and Tg DSC onset temperature higher than 10 °C as the present conjugated diene polymer (I) does. These conventional polymers or copolymers may be of natural origin or may be obtained by solution polymerization, emulsion polymerization or gas-phase polymerization of one or more conjugated dienes, optionally mixed with at least one comonomer, preferably selected from monoolefins, monovinylarenes and / or polar comonomers, typically in an amount not exceeding 60% by weight.

[0128] The conjugated dienes generally comprise from 4 to 12, preferably from 4 to 8 carbon atoms and may be selected, for example, from the group comprising: 1 ,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 3-butyl-1,3-octadiene, 2-phenyl-1,3-butadiene and mixtures thereof. 1,3-butadiene and isoprene are particularly preferred. The monoolefins can be selected from ethylene and a-olefins generally comprising from 3 to 12 carbon atoms, such as for example propylene, 1 -butene, 1 -pentene, 1 -hexene, 1-octene or mixtures thereof.

[0129] Monovinylarenes, which may optionally be used as comonomers, generally comprise from 8 to 20, preferably from 8 to 12 carbon atoms and may be selected, for example, from: styrene; 1-vinylnaphthalene; 2-vinylnaphthalene; various alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl derivatives of styrene, such as, for example, a-methylstyrene, 3-methylstyrene, 4-propylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4-p-tolyl-styrene, 4- (4-phenylbutyl)styrene, and mixtures thereof. Styrene is particularly preferred. Polar comonomers that may optionally be used, can be selected, for example, from among acrylic acid and alkylacrylic acid esters, acrylonitriles, or mixtures thereof, such as, for example, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, acrylonitrile and mixtures thereof.

[0130] Preferably, the elastomeric polymer may be selected, for example, from cis-1,4-polyisoprene (natural or synthetic, preferably natural rubber), 3,4-polyisoprene, polybutadiene (in particular polybutadiene with a high content of 1,4-cis), isoprene / isobutene copolymers, halogenated isoprene / isobutene copolymers, 1,3-butadiene / acrylonitrile copolymers, styrene / 1,3-butadiene copolymers, styrene / isoprene / 1 ,3-butadiene copolymers, styrene / 1 ,3-butadiene / acrylonitrile copolymers, and mixtures thereof.

[0131] The cross-linkable elastomeric composition may optionally comprise at least one polymer of one or more monoolefins with an olefinic comonomer or derivatives thereof. The monoolefins can be selected from: ethylene and a-olefins generally comprising from 3 to 12 carbon atoms, such as for example propylene, 1 -butene, 1 -pentene, 1 -hexene, 1 -octene or mixtures thereof. The following are preferred: copolymers selected from ethylene and an a-olefin, optionally with a diene; isobutene homopolymers or copolymers thereof with small amounts of a diene, which are optionally at least partially halogenated. The diene optionally present generally comprises from 4 to 20 carbon atoms and is preferably selected from: 1,3-butadiene, isoprene, 1,4-hexadiene, 1,4-cyclohexadiene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, vinylnorbornene or mixtures thereof. Among them, the following are particularly preferred: ethylene / propylene (EPR) copolymers or ethylene / propylene / diene (EPDM) copolymers; polyisobutene; butyl rubber; halobutyl rubbers, in particular chlorobutyl or bromobutyl rubbers; and mixtures thereof.

[0132] In the conventional known elastomeric polymers, the distribution of vinyl units and aromatic vinyl units is either random or it does not provide first and second polymers segments as the present ones of the conjugated diene polymer (I).

[0133] The above-mentioned polymers can optionally be functionalised along the main chain or at the ends thereof.

[0134] The functional group may be introduced into the elastomeric polymer by processes known in the art such as, for example, during the production of the elastomeric polymer by copolymerisation with at least one corresponding functionalised monomer comprising at least one ethylene unsaturation; or by subsequent modification of the elastomeric polymer by grafting at least one functionalised monomer in the presence of a free radical initiator (for example, an organic peroxide). Alternatively, the functionalisation may be introduced by reaction with suitable terminating agents or coupling agents.

[0135] The elastomeric composition of the invention comprises a plasticizing admixture.

[0136] The Applicant has unexpectedly found that by combining the above conjugated diene polymer (I) as sole or main elastomeric polymer of the present elastomeric composition with a proper plasticizing admixture it is possible to provide elastomeric compounds having grip improvement, both on dry and wet surfaces and low rolling resistance, together with reduced wear, particularly advantageous for use in summer tyres. This improvement in summer performance is well illustrated in Figure 3 where the hysteresis of the elastomeric compound on the invention (Ex. 4A mixed point and hatch line) is clearly higher just in the temperature range of interest for summer applications. Preferably, the present elastomeric composition comprises from 40 phr to 75 phr of the plasticizing admixture, more preferably from 55 phr to 70 phr.

[0137] The plasticizing admixture comprises at least a solid resin, at least a liquid resin and, optionally, at least an oil and / or at least a liquid polymer.

[0138] The plasticizing admixture of the present elastomeric composition preferably comprises:

[0139] 20 phr to 40 phr of at least a solid resin

[0140] 10 phr to 40 phr of at least a liquid resin

[0141] 0 to 20 phr of at least an oil

[0142] 0 to 25 phr of at least a liquid polymer.

[0143] The plasticizing admixture of the present elastomeric composition more preferably comprises:

[0144] 25 phr to 35 phr of at least a solid resin

[0145] 15 phr to 35 phr of at least a liquid resin

[0146] 0 to 10 phr of at least an oil

[0147] 0 to 10 phr of at least a liquid polymer.

[0148] The plasticizing admixture comprises at least a solid resin and at least a liquid resin, in overall amount preferably from 40 phr to 75 phr, more preferably from 55 phr to 65 phr. The plasticizing admixture comprises at least a solid resin, preferably in amount from 25 phr to 35 phr and at least a liquid resin, preferably in amount from 15 phr to 35 phr.

[0149] The resins of the present composition are non-reactive resins.

[0150] With the term “solid resin” a resin which is solid at 25 °C is meant.

[0151] The solid resin typically has a softening temperature (Tm) higher than 25°C.

[0152] With the term “liquid resin” a resin which is liquid at 25 °C is meant.

[0153] The liquid resin typically has a softening temperature (Tm) not higher than 25°C.

[0154] The resins of the present composition can be characterized inter alia by a weight average molecular weight, a glass transition temperature (Tg) and / or a softening temperature (Tm). The glass transition temperature (Tg) and the softening temperature (Tm) can conveniently be measured using a differential scanning calorimeter (DSC) according to methods well known to the man skilled in the art, such as the ASTM D 6604 method (Glass Transition Temperatures of Hydrocarbon resins by Differential Scanning Calorimetry).

[0155] Preferably, the solid resin is characterized by a weight average molecular weight of between 200 and 6000 g / mol, preferably between 300 and 4000 g / mol.

[0156] Preferably, the liquid resin is characterized by a weight average molecular weight of between 200 and 6000 g / mol, preferably between 300 and 4000 g / mol.

[0157] The weight average molecular weight (Mw) of resins may be measured according to techniques known in the field such as, for example, by SEC (Size-Exclusion Chromatography) according to the ASTM D6579-11 method “Standard Practice for Molecular Weight Averages and Molecular Weight Distribution of Hydrocarbon, Rosin and Terpene Resins by Size-Exclusion Chromatography”.

[0158] Preferably, the solid resin is characterized by a glass transition temperature (Tg) higher than 0 °C, more preferably higher than 25 °C.

[0159] Preferably, the liquid resin is characterized by a glass transition temperature (Tg) lower than 25 °C, more preferably lower than 0 °C.

[0160] Preferably, the solid resin has a softening temperature (Tm) higher than 40 °C, more preferably higher than 60°C, even more preferably higher than 70°C. Preferably, the solid resin has a softening temperature from 50 °C to 160 °C, more preferably from 70 °C to 140 °C, even more preferably from 80 °C to 120 °C.

[0161] Preferably, the liquid resin has a softening temperature lower than 20 °C, more preferably lower than 15 °C, possibly lower than 0 °C or than -10 °C or than -25 °C.

[0162] The resins used in the present composition are preferably selected among hydrocarbon resins, phenolic resins, natural resins, their derivatives and mixtures thereof.

[0163] The hydrocarbon resin may be aliphatic, aromatic or combinations thereof, meaning that the base polymer of the resin can consist of aliphatic and / or aromatic monomers.

[0164] The hydrocarbon resin may be natural (e.g. vegetable) or synthetic or derived from petroleum. In some cases, non-limiting for the invention, these resins essentially contain only hydrogen and carbon atoms.

[0165] The hydrocarbon resin can be selected from homo- or copolymers of cyclopentadiene (CPD), dicyclopentadiene (DCPD), homo- or copolymers of terpene, homo- or copolymers of the C5 fraction and mixtures thereof, preferably DCPD / vinyl aromatic copolymers, DCPD / terpene copolymers, DCPD / C5 fraction copolymers, terpene / vinyl aromatic copolymers, C5 fractions / vinyl aromatic copolymers and combinations thereof.

[0166] Examples of vinyl aromatic monomers include styrene, alpha-methylstyrene, ortho-, meta-, paramethylstyrene, vinyl-toluene, para-tert-butylstyrene, methoxy-styrenes, chlorostyrenes, vinyl mesitylene, divinyl-benzenes, vinyl-naphthalenes, vinyl aromatic monomers derived from C8-C10 fraction, in particular from C9.

[0167] A specific example of commercially available resins of this kind is HT-100 by Hanwha. The hydrocarbon resin can be selected from resins derived from coumarone-indene, styrene-indene, styrene-alkylstyrene, and aliphatic resins.

[0168] Specific examples of commercially available hydrocarbon resins are NOVARES C resins by RUTGERS CHEMICAL GmbH (indene-coumarone synthetic resins) NOVARES C10, C30 and C90 being particularly preferred. Examples of commercially available styrene-indene hydrocarbon resins are UNILENE At 100 by Braskem, and Novares TL 90 by Rain Carbon.

[0169] Examples of commercially available alkyl-styrene hydrocarbon resins are: Sylvares SA 85 by Arzona Chemical, Kristalex F 85 by Synthomer, Kristalex 5140 by Synthomer.

[0170] Examples of commercially available aliphatic hydrocarbon resins are: Escorez® 1102 (by ExxonMobil), Piccotac 1100 (by Eastman), Quintone A 100 (by Zeon Chemicals).

[0171] The hydrocarbon resin can be a phenolic resin. The phenolic resin can be selected from among the resins alkylphenol-formaldehyde based, alkylphenolic resins modified with rosin, resins alkylphenol-acetylene based, modified alkylphenolic resins and resins terpenephenol based.

[0172] Examples of commercially available phenolic resins that can be used in the present invention are: RESINA SP-1068 (by SI GROUP Inc.) (octylphenol-formaldehyde resin); DUREZ 32333 (by Sumitomo Bakelite) (phenol-formaldehyde resin); KORESIN (by BASF Company) (p t-butylphenol-acetylene resin); SYLVARES TP 115 (by Arizona Chemicals) (terpen-phenolic resin).

[0173] The phenolic resin can be a natural resin based on terpene.

[0174] The phenolic resin can be a polyterpene resin selected from the homo- or copolymers of alpha-pinene, beta-pinene, limonene, and vinyl aromatic monomers (styrene) and / or aromatic monomers (phenol).

[0175] Examples of commercially available natural terpene-based resins that can be used in the present invention are: Piccolyte F90 and Piccolyte F105 by PINOVA; Dercolyte A 115 and Dercolyte M 115 by DRT.

[0176] The phenolic resin can be a natural resin based on rosin.

[0177] The term rosin commonly indicates mixtures of isomer organic acids (rosin acids), characterized by a common structure, comprising three C6 fused rings, double bonds in different number and positions and a single carboxylic group.

[0178] Examples of rosin-based resins are HYDROGRAL G, DERTOLINE P 105, Granolite TEG and Dertoline DEG 2 marketed by DRT or STAYBELITE™ ESTER 3-E by Synthomer. Preferably, the solid resin is selected among KRISTALEX F 85 by Synthomer, HT-100 by Hanwha, Escorez® 1102 by ExxonMobil, Novares TL 90 by Rain Carbon, more preferably HT-100 by Hanwha and Kristalex F 85 Synthomer.

[0179] Preferably, the liquid resin is selected among STAYBELITE™ ESTER 3-E by Synthomer, Granolite TEG and Dertoline DEG 2 marketed by DRT, more preferably is STAYBELITE™ ESTER 3-E by Synthomer.

[0180] The plasticizing admixture may comprise at least an oil. Preferably, the one or more oils may be present in a total amount of at most 10 phr, more preferably of at most 8 phr. Preferably, the one or more oils may be present in a total amount from 1 to 25 phr, 2 to 20 phr, more preferably from 2 to 10 phr, even more preferably from 5 to 8 phr.

[0181] The oil may be contained, in full or in part, in the composition of the elastomeric polymer and / or the conjugated diene polymer (I), where it acts as a thinner (extender).

[0182] The oil can be a process oil derived from petroleum or a mineral oil or a vegetable oil or a synthetic oil or combinations thereof.

[0183] The oil may have one or more of the following features:

[0184] - a weight average molecular weight not higher than 600 g / mol or, if the class of the RAE, a weight average molecular weight of between 400 and 10000 g / mol,

[0185] - a glass transition temperature (Tg DSC) lower than -30 °C.

[0186] The present oil can be an oil derived from petroleum selected from paraffins (saturated hydrocarbons), naphthenes, aromatic polycyclic and mixtures thereof. Examples of suitable process oils derived from petroleum are aromatic, paraffinic, naphthenic oils such as MES (Mild Extract Solvated), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), RAE (Residual Aromatic Extract) known in the art. The present oil can be a process oil derived from petroleum with a low aromatic content, selected for example from TDAE, TRAE, MES, paraffinic or naphthenic oils. Examples of suitable oils derived from petroleum are NYTEX 4700 by Nynas, EXTENSOIL 1471 by Repsol, VIVATEC 500 by H&R. Examples of suitable vegetable oils are sunflower, soybean, linseed, rapeseed, castor and cotton oil. Examples of suitable commercial vegetable oils are RADIA 6132 by Oleon, Agripure AP 18 and Agripure AP 75 by Cargill, soyabean oil by Wilmar.

[0187] The present oil can be an oil of natural or synthetic origin derived from the esterification of glycerol with fatty acids, comprising glycerin triglycerides, diglycerides, monoglycerides or mixtures thereof. Preferably, these oils have a glass transition temperature (Tg) lower than -70 °C. The present oil can be a synthetic oil selected from among the alkyl or aryl esters of phthalic acid or phosphoric acid. Preferably, these esters have a glass transition temperature (Tg) lower than -70 °C.

[0188] These oils may be used alone or in admixture.

[0189] The plasticizing admixture may comprise at most 30 phr or 25 phr, preferably at most 20 phr, more preferably at most 10 phr, even more preferably at most 5 phr of at least a liquid polymer. The liquid polymer may be a liquid polybutadiene, a liquid polyisoprene, liquid polystyrene-butadiene, or their mixtures. The term "liquid polymer" means a diene polymer derived from the polymerisation of one or more monomers, among which at least one is a conjugated diene, said polymer at the temperature of 25 °C being a pourable liquid or a low viscosity fluid. Preferably, the liquid polymer is characterized by one or more of the following: a weight average molecular weight not higher than 80000 g / mol, a glass transition temperature (Tg) lower than 0 °C.

[0190] The weight average molecular weight (Mw) may be measured according to known techniques in the field such as for example by GPC (Gel Permeation Chromatography) according to the ISO 13885 method.

[0191] The glass transition temperature Tg can be conveniently measured by using a differential scanning calorimeter (DSC) according to methods well known to those skilled in the art (ISO 22768 "Rubber, Raw - Determination of the glass transition temperatures by differential scanning calorimetry (DSC)".

[0192] Preferably, the liquid polymer is characterized by a (Mw) of between 500 and 80000 g / mol, more preferably between 500 and 60000 g / mol. Preferably, the liquid polymer is characterized by a glass transition temperature (Tg) of between -105 °C and 0 °C, more preferably between -100 °C and -20 °C.

[0193] Optionally, the liquid polymer can be modified with maleic anhydride, esterified or acid carboxylic groups, epoxy groups or hydroxyl groups or trialkoxy-silyl groups.

[0194] Examples of suitable liquid polybutadienes are liquid polymers based on butadiene (BR) marketed by Evonik under the trade name POLYVEST 110, POLYVEST 130, POLYVEST MA 75; by Kuraray under the trade name LBR 307, LBR 305, LBR 300; and by Cray Valley under the trade name RICON 130, RICON 130 MA8, RICON 130 MA 13, RICON 150, RICON 156, RICON 157.

[0195] The at least one liquid polymer can be a liquid polyisoprene (IR), optionally mixed with a liquid polybutadiene. Examples of suitable liquid polyisoprenes are the liquid polymers marketed by Kuraray under the trade name LIR 30, LIR 50, LIR 403, LIR 410, the DPR35, DPR 40, DPR75, DPR 400 polymers of DPR INDUSTRIES.

[0196] The components of the plasticizing admixture are not necessarily pre-mixed together to give a separate plasticizing admixture but in the preparation they may be added to the composition individually, in any sequence or step of the preparation process, or may be associated in whole or in part with one or more of the other components, such as in the case of the oils which can be, at least in part, already incorporated into the elastomeric materials as extenders.

[0197] The present plasticizing admixture, containing resins in high amount and minimum amounts of oils, improves the wet and dry grip balance of the resulting elastomeric compound. The elastomeric composition of the invention comprises at least a reinforcing filler.

[0198] The present elastomeric composition preferably comprises at least 10 phr or 20 phr or 30 phr or 40 phr, more preferably at least 40 phr or 50 phr, even more preferably at least 60 phr or 70 phr of at least a reinforcing filler. The present elastomeric composition may comprise from 50 phr to 140 phr, preferably from 70 phr to 130 phr, more preferably from 100 phr to 120 phr of at least one reinforcing filler. Preferably, the reinforcing filler is selected from carbon black, white fillers, silicate fibres, derivatives and mixtures thereof.

[0199] The reinforcing filler may be a white filler selected from among hydroxides, oxides and hydrated oxides, salts and hydrated salts of metals, silicates fibres, derivatives thereof and mixtures thereof. Preferably, said white filler is silica. Commercial examples of suitable silica are Zeosil 1165 MP, Zeosil 1115 MP, Zeosil 185 GR, Efficium from Solvay, Newsil HD90 and Newsil HD200 from Wuxi, K160 and K195 from Wilmar, H160AT and H180 AT from IQE, Zeopol 8755 and 8745 from Huber, Perkasil TF100 from Grace, Hi-Sil EZ 120 G, EZ 160G, EZ 200G from PPG, Ultrasil 7000 GR and Ultrasil 9100 GR from Evonik, K 160 (silica from rice husk) by Wilmar. The reinforcing filler may be silica mixed with carbon black. The reinforcing filler may be a modified silica. Silica may be modified for instance by reaction with silsequioxanes (as in W02018078480A1), with pyrroles (as in W02016050887A1) or with silanizing agents. Commercial examples of suitable silanizing agents are Si69, Dynasilan AMEO and Dynasilan GLYEO from Evonik. The modified silica may be a sulfurized silanized silica. Sulphurized silanized silica is a silica prepared by reaction of a silica or of a metal silicate, with at least one sulfurized silanizing agent. A commercial example of suitable sulfurized silanized silica is Agilon 400 silica from PPG. The reinforcing filler may be a modified silica mixed with carbon black. The reinforcing filler may be a silicate for instance selected among lamellar silicates (e.g. bentonites, alloysite, laponite, saponite, vermiculite or hydrotalcite) or silicate fibres (e.g. sepiolite fibres, paligorskite fibres also known as attapulgite, wollastonite fibres, imogolite fibres) optionally modified, or their admixtures. The reinforcing filler may be silicate fibres mixed with carbon black.

[0200] The reinforcing filler may be modified silicate fibres, such as those described in WO2016174629A1, in WO2016174628A1, those organically modified by reaction, for example, with quaternary ammonium salts or with a silanizing agent.

[0201] In one embodiment, said reinforcing filler is carbon black, preferably selected from those having a surface area not smaller than 20 m2 / g, preferably larger than 50 m2 / g (as determined by STSA - statistical thickness surface area according to ISO 18852:2005). Carbon black may be for example N110, N115, N121, N134, N220, N234, N326, N330, N375 or N550, N660 marketed by Birla Group (India) or by Cabot Corporation, Vulcan® 1391 supplied by Cabot Corporation or Birla Carbon™ 2115 supplied by Birla Group. The elastomeric composition of the invention comprises at least a vulcanizing agent.

[0202] Preferably, the elastomeric composition comprises at least 0.6 phr, 0.7 phr, 0.8 phr or 1 phr of at least one vulcanizing agent. Preferably, the composition comprises from 0.5 to 10 phr, from 0.8 to 10 phr, from 1 to 10 phr or from 1.5 to 5 phr of at least one vulcanizing agent. The at least one vulcanizing agent is preferably selected from sulfur, sulfurized agents (sulfur donors), such as, for example, bis[(trialkoxysilyl)propyl]polysulphides, caprolactamdisulphide or peroxides and mixtures thereof. Preferably, the vulcanizing agent is sulfur, preferably selected from soluble sulfur (crystalline sulfur), insoluble sulfur (polymeric sulfur), oil-dispersed sulfur and mixtures thereof. Commercial example of a vulcanizing agent suitable for use in the cross-linkable elastomeric composition is the soluble sulfur of Zolfindustria (Italy).

[0203] In the present elastomeric composition, the vulcanizing agent may be used together with adjuvants such as vulcanization activators, accelerators and / or retardants known to those skilled in the art.

[0204] The present elastomeric composition may optionally comprise at least one vulcanization activator. Vulcanization activators suitable for use in the present elastomeric composition are zinc compounds, in particular ZnO, ZnCO3, zinc salts of saturated or unsaturated fatty acids comprising from 8 to 18 carbon atoms, which are preferably formed in situ in the elastomeric composition by reaction of ZnO and of the fatty acid or mixtures thereof. For example, zinc stearate is used, preferably zinc stearate formed in situ in the elastomeric composition, from ZnO and fatty acid, or magnesium stearate, formed from MgO, or mixtures thereof. The vulcanization activator may be present in the elastomeric composition in amounts preferably from 0.2 phr to 15 phr, more preferably from 1 phr to 5 phr. Preferred activating agents derive from the reaction of zinc oxide and stearic acid. An example of activator is the product Aktiplast ST marketed by Rheinchemie.

[0205] The present elastomeric composition may further comprise at least one vulcanization accelerator. Vulcanization accelerators that are commonly used may be, for example, selected from dithiocarbamates, guanidines, thioureas, thiazoles, sulphenamides, sulphenimides, thiurams, amines, xanthates, or mixtures thereof. Preferably, the accelerator agent is selected from mercaptobenzothiazole (MBT), N-cyclohexyl-2-benzothiazol-sulphenamide (CBS), N-tert-butyl-2-benzothiazol-sulphenamide (TBBS) and mixtures thereof. Commercial examples of accelerators suitable for use in the present elastomeric composition are N-cyclohexyl-2-benzothiazyl-sulphenamide Vulkacit® (CBS or CZ), and N-terbutyl 2-benzothiazil sulphenamide, Vulkacit® NZ / EGC marketed by Lanxess. Vulcanization accelerators may be used in the present elastomeric composition in an amount preferably from 0.05 phr to 10 phr, preferably from 0.1 phr to 7 phr, more preferably from 0.5 phr to 5 phr.

[0206] The present elastomeric composition may optionally comprise at least one vulcanization retardant agent. The vulcanization retardant agent suitable for use in the present elastomeric composition is preferably selected from urea, phthalic anhydride, N- nitrosodiphenylamine N-cyclohexylthiophthalimide (CTP or PVI) and mixtures thereof. A commercial example of a suitable retardant agent is N-cyclohexylthiophthalimide VULKALENT G of Lanxess. The vulcanization retardant agent may be present in the present elastomeric composition in an amount of preferably from 0.05 phr to 2 phr. The present elastomeric composition may comprise one or more vulcanization retardant agents as defined above in a mixture.

[0207] The present elastomeric composition may further comprise at least 0.05 phr, preferably at least 0.1 phr or 0.5 phr, more preferably at least 1 phr or 2 phr of at least one silane coupling agent. Preferably, the elastomeric composition comprises from 0.1 phr to 20.0 phr or from 0.5 phr to 10.0 phr, even more preferably from 1.0 phr to 5.0 phr of at least one silane coupling agent. Preferably, said coupling agent is a silane coupling agent selected from those having at least one hydrolysable silane group which may be identified, for example, by the following general formula:

[0208] (R’)3Si-CnH2n-X

[0209] wherein the groups R’, equal or different from each other, are selected from: alkyl, alkoxy or aryloxy groups or from halogen atoms, provided that at least one of the groups R’ is an alkoxy or an aryloxy group; n is an integer of from 1 to 6; X is a group selected from: nitrous, mercapto, amino, epoxide, vinyl, imide, chloro, -(S)mCnH2n-Si-(R’)3 and -S-COR’ group, wherein m and n are integers from 1 to 6 and R’ groups are as defined above.

[0210] Particularly preferred silane coupling agents are bis(3-triethoxysilylpropyl)tetrasulphide and bis(3-triethoxysilylpropyl)disulphide. Said coupling agents may be added as such or in mixture with an inert filler (such as carbon black) so as to facilitate their incorporation into the elastomeric composition. An example of a silane coupling agent is TESPT bis(3-triethoxysilylpropyl)tetrasulphide Si69 marketed by Evonik.

[0211] The present elastomeric composition may further comprise one or more additional ingredients, commonly used in the field, such as for instance antioxidant and / or anti-ozone agents (anti-aging agents), waxes, adhesives and the like.

[0212] The elastomeric composition may optionally comprise at least one wax. The wax may be for example a petroleum wax or a mixture of paraffins. Commercial examples of suitable waxes are Repsol N-paraffin mixture, Antilux® 654 microcrystalline wax from Rhein Chemie, and the paraffin wax RIOWAX BN01 by SER S.p.A.

[0213] The wax may be present in the elastomeric composition in an overall amount generally from 0.1 phr to 20 phr, preferably from 0.5 phr to 10 phr, more preferably from 1 phr to 5 phr. The elastomeric composition may optionally comprise at least one antioxidant agent. The antioxidant agent is preferably selected from N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), N-(-1,3-dimethyl-butyl)-n'-phenyl-p-phenylenediamine (6PPD), N,N'-bis-(1 ,4- dimethyl-pentyl)-p-phenylenediamine (77PD), N,N'-bis-(1-ethyl-3-methyl-pentyl)-p-phenylenediamine (DOPD), N,N'-bis-(1,4-dimethyl-pentyl)-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-ditolyl-p-phenylenediamine (DTPD), N,N'-di-beta-naphthyl-p-phenylenediamine (DNPD), N,N'-bis(1-methylheptyl)-p-phenylenediamine, N,N'-Di-sec-butyl-p-phenylenediamine (44PD), N-phenyl-N-cyclohexyl-p-phenylenediamine, N-phenyl-N '-1-methylheptyl-p-phenylenediamine and the like, and mixtures thereof, preferably it is N-1,3-dimethylbutyl-N-phenyl-p-phenylenediamine (6-PPD). A commercial example of a suitable antioxidant agent is 6PPD Santoflex produced by Flexsys. The antioxidant agent may be present in the elastomeric composition in an overall amount preferably from 0.1 phr to 20 phr, more preferably from 0.5 phr to 10 phr. In one preferred embodiment, the elastomeric composition comprises:

[0214] - 100 phr of a conjugated diene polymer (I), the conjugated diene polymer (I) comprising first and second segments as previously defined, having a Tg Dscfrom -65 °C to -55 °C, an absolute difference between Tg DSC end temperature and Tg DSC onset temperature between 12 °C and 15 °C,

[0215] - 60 phr to 70 phr of a plasticizing admixture comprising

[0216] 25 phr to 30 phr of at least a solid resin

[0217] 15 phr to 35 phr of at least a liquid resin

[0218] lower than 10 phr of at least an oil,

[0219] - from 100 phr to 120 phr, of a reinforcing filler, and

[0220] - at least 0.5 phr of a vulcanizing agent.

[0221] The present elastomeric compound is characterized by a particular hysteresis pattern. In fact, unlike known elastomeric compounds comprising conventional SBRs, for example the compound of Ex. 2A (see Figure 3) - where the tan delta curve shows a narrow high peak centred around the Tg temperature of the compound with a steep decrease after the peak as T increases and low Tan D values in the region from -10 °C to +30 °C - the compounds of the invention (see Ex. 4A , Figure 3) instead show a broad flattened Tan D peak with a less steep downward slope and higher Tan D values, in the temperature range from -10 °C to +30 °C predictive of improved wet grip performance.

[0222] In addition, the compounds of the invention (Ex. 1B vs EX. 1A and Ex. 1C) are endowed with a lower Payne effect (see Table 4) indicating that the dispersion of the filler into the polymer matrix is improved. Finally, the present elastomeric compounds showed similar Mooney viscosity compared to reference compounds (see Ex. 2B to Ex. 2F vs Ex. 2A), denoting a good compound processability and static properties in line (see Table 6). The present elastomeric compound may be prepared by a conventional process comprising, for instance, a first non-productive step and a second productive step, followed by cross-linking. The process typically comprises:

[0223] - in the first non-productive step, mixing the elastomeric polymer(s) including the present conjugated diene polymer (I), a reinforcing filler, a solid and a liquid resin and optionally other possible ingredients such as an oil, a liquid polymer, an antioxidant, a compatibilizing agent, an anti-ozone and / or a wax but the vulcanizing agent, at a temperature between 110 and 190 °C, to give a first elastomeric compound,

[0224] - in the second productive step, adding to the first elastomeric compound a curing system comprising at least a vulcanizing agent and optionally an accelerator agent, a retardant agent, a vulcanization activating agent - and mixing the components at a temperature preferably lower than 120 °C, to give a elastomeric compound, and

[0225] - cross-linking the cross-linkable elastomeric compound, at a temperature preferably between 150 °C and 180 °C, to give the cross-linked elastomeric compound.

[0226] The process according to the invention typically comprises one or more thermomechanical mixing steps in at least one suitable mixer, in particular at least a first mixing step (step 1 -non-productive) and a second mixing step (step 2 - productive) as defined above.

[0227] Each mixing step may comprise several intermediate processing steps or sub-steps, characterized by the momentary interruption of the mixing to allow the addition of one or more ingredients but without intermediate dumping of the compound. The mixing may be performed, for example, using an open mixer of the “open-mill” type or an internal mixer of the type with tangential rotors (Banbury®) or with interpenetrating rotors (Intermix), or in continuous mixers of the Ko-Kneader™ type (Buss®) or of the twin-screw or multi-screw type. Generally, but not necessarily, at the end of step 1 the first elastomeric compound is unloaded and after a variable period it is reloaded in the same or another suitable mixer, for the subsequent productive step 2. In productive step 2, the temperature is generally controlled to avoid undesired pre-vulcanization phenomena. At the end of the second step, the cross-linkable elastomeric compound is incorporated into one or more components of the green tyre and subjected to vulcanization, according to known techniques. Any of the usual vulcanization processes may be used in the present process, such as heating in a press or mold, heating with superheated steam or hot air.

[0228] The tyre component comprising, preferably consisting of the above cross-linked elastomeric compound is preferably selected from tread band, under-layer, anti-abrasive strip, sidewall, sidewall insert, mini-sidewall, liner, under-liner, rubber layers, bead filler, bead reinforcing layers (flipper), bead protection layers (chafer) and sheet. Preferably, the tyre component is a tread band. The tyre for vehicle wheels of the invention comprises at least one of the - 1 - components comprising a vulcanized elastomeric compound obtained by vulcanization of the elastomeric composition described above. Preferably, said component is at least the tread band.

[0229] In one embodiment, the tyre for vehicles according to the present invention comprises at least:

[0230] - a carcass structure comprising at least a carcass ply having opposite lateral edges associated to respective bead structure;

[0231] - optionally a pair of sidewalls applied to the lateral surfaces of the carcass structure, respectively, in an axially outer position;

[0232] - optionally a belt structure applied in radially outer position with respect to the carcass structure;

[0233] - a tread band applied in a radially outer position to said carcass structure or, if present, a belt structure,

[0234] - optionally a layer of elastomeric material, referred to as under-layer, applied in a radially inner position with respect to said tread band,

[0235] wherein at least one component, preferably the tread band, comprises or preferably consists of the present cross-linked elastomeric compound.

[0236] In a preferred embodiment, the tyre according to the invention can be prepared by a process comprising:

[0237] (a) producing a raw tyre comprising a raw tread band applied at a radially outer position of the tyre;

[0238] (b) subjecting said raw tyre to molding and vulcanization so as to obtain a finished tyre; in which said raw tread band comprises or preferably consists of the elastomeric composition described above.

[0239] The tyre according to the invention may be for all seasons or preferably for summer use. In one embodiment, the tyre according to the invention is a tyre for a passenger car, with normal or high performance or for off-road vehicles, preferably a tyre for passengers, conceived for vehicles for personal use, such as sedans, coupes, crossovers, SLIVs, minivans and small pickups. In one embodiment, the tyre according to the invention is a tyre for motorcycles, wherein at least one component comprises or, preferably, consists of the present cross-linked elastomeric compound. The tyre according to the invention may be a tyre for two, three or four-wheeled vehicles.

[0240] In one embodiment, the tyre according to the invention is a tyre for bicycle wheels. A tyre for bicycle wheels typically comprises a carcass structure turned around a pair of bead cores at the beads and a tread band arranged in a radially outer position with respect to the carcass structure. Preferably, at least the tread band comprises or preferably consists of the present cross-linked elastomeric compound. The tyre for vehicles wheels may be built, formed, molded and vulcanized with various methods known to the skilled in the art.

[0241] DESCRIPTION OF A TYRE ACCORDING TO THE INVENTION

[0242] A tyre for vehicle wheels according to the invention, comprising at least one component comprising the present elastomeric compound, is illustrated in radial half-section in Figure 1. In Figure 1, "a" indicates an axial direction and "X" indicates a radial direction, in particular X-X indicates the outline of the equatorial plane. For simplicity, Figure 1 shows only a portion of the tyre, the remaining portion not shown being identical and arranged symmetrically with respect to the equatorial plane "X-X". The tyre (100) for four-wheeled vehicles comprises at least one carcass structure, comprising at least one carcass layer (101) having respectively opposite end flaps engaged with respective annular anchoring structures (102), referred to as bead cores, possibly associated to a bead filler (104). The tyre area comprising the bead core (102) and the filler (104) forms a bead structure (103) intended for anchoring the tyre onto a corresponding mounting rim, not shown. The carcass structure is usually of radial type, i.e. the reinforcing elements of the at least one carcass layer (101) lie on planes comprising the rotational axis of the tyre and substantially perpendicular to the equatorial plane of the tyre. Said reinforcing elements generally consist of textile cords. Each bead structure is associated to the carcass structure by folding back of the opposite lateral edges of the at least one carcass layer (101) around the annular anchoring structure (102) so as to form the so-called carcass flaps (101a) as shown in Figure 1. In one embodiment, the coupling between the carcass structure and the bead structure can be provided by a second carcass layer (not shown in Figure 1) applied in an axially outer position with respect to the first carcass layer. An anti-abrasive strip (105) possibly made with elastomeric material is arranged in an outer position of each bead structure (103). The carcass structure is associated to a belt structure (106) comprising one or more belt layers (106a), (106b) placed in radial superposition with respect to one another and with respect to the carcass layer, having typically textile and / or metallic reinforcing cords incorporated within a layer of elastomeric material. Such reinforcing cords may have crossed orientation with respect to a direction of circumferential development of the tyre (100). By "circumferential" direction it is meant a direction generally facing in the direction of rotation of the tyre. At least one zero-degree reinforcement layer (106c), commonly known as a "0° belt", may be applied in a radially outermost position to the belt layers (106a), (106b), which generally incorporates a plurality of elongated reinforcing elements, typically metallic or textile cords, oriented in a substantially circumferential direction, thus forming an angle of a few degrees (such as an angle of between about 0° and 6°) with respect to a direction parallel to the equatorial plane of the tyre, and coated with an elastomeric material. A tread band (109) comprising the elastomeric compound according to the invention is applied in a position radially outer to the belt structure (106). Moreover, respective sidewalls (108) of elastomeric material are applied in an axially outer position on the lateral surfaces of the carcass structure, each extending from one of the lateral edges of tread (109) at the respective bead structure (103). In a radially outer position, the tread band (109) has a rolling surface (109a) intended to come in contact with the ground. Circumferential grooves, which are connected by transverse notches (not shown in Figure 1) so as to define a plurality of blocks of various shapes and sizes distributed over the rolling surface (109a), are generally made on this surface (109a), which for simplicity is represented smooth in Figure 1. An under-layer (111) comprising the elastomeric compound according to the invention can be arranged between the belt structure (106) and the tread band (109). A strip consisting of elastomeric material (110), commonly known as "mini-sidewall", can optionally be provided in the connecting zone between the sidewalls (108) and the tread band (109), this mini-sidewall being generally obtained by co-extrusion with the tread band (109) and allowing an improvement of the mechanical interaction between the tread band (109) and the sidewalls (108). Preferably, the end portion of the sidewall (108) directly covers the lateral edge of the tread band (109). In the case of tubeless tyres, a rubber layer (112), generally known as "liner", which provides the necessary impermeability to the inflation air of the tyre, can also be provided in a radially inner position with respect to the carcass layer (101). The rigidity of the tyre sidewall (108) can be improved by providing the bead structure (103) with a reinforcing layer (120) generally known as flipper or additional strip-like insert. The flipper (120) is a reinforcing layer which is wound around the respective bead core (102) and the bead filler (104) so as to at least partially surround them, said reinforcing layer being arranged between the at least one carcass layer (101) and the bead structure (103). Usually, the flipper is in contact with said at least one carcass layer (101) and said bead structure (103). The flipper (120) typically comprises a plurality of textile cords incorporated within a layer of elastomeric material. The reinforcing annular structure or bead (103) of the tyre may comprise a further protective layer which is generally known by the term of "chafer" (121) or protective strip and which has the function of increasing the rigidity and integrity of the bead structure (103). The chafer (121) usually comprises a plurality of cords incorporated within a rubber layer of elastomeric material. Such cords are generally made of textile materials (such as aramid or rayon) or metal materials (such as steel cords). A layer or sheet of elastomeric material can be arranged between the belt structure and the carcass structure. The layer can have a uniform thickness. Alternatively, the layer may have a variable thickness in the axial direction. For example, the layer may have a greater thickness close to its axially outer edges with respect to the central (crown) zone. Advantageously, the layer or sheet can extend on a surface substantially corresponding to the extension surface of said belt structure. In a preferred embodiment, a layer of elastomeric material, referred to as under-layer, can be placed between said belt structure and said tread band, said under-layer preferably extending on a surface substantially corresponding to the extension surface of said belt structure.

[0243] The elastomeric compound according to the present invention may be advantageously incorporated into one or more of the tyre components mentioned above, preferably at least in the tread band. According to an embodiment not shown, the tyre may be a tyre for motorcycle wheels which is typically a tyre that has a straight section featuring a high tread camber.

[0244] The manufacture of the tyre (100) as described above, can be carried out by assembling respective semi-finished products adapted to form the components of the tyre, on a forming drum, not shown, by at least one assembling device. At least a part of the components intended to form the carcass structure of the tyre can be built and / or assembled on the forming drum. More particularly, the forming drum is intended to first receive the possible liner, and then the carcass structure. Thereafter, devices non shown coaxially engage one of the annular anchoring structures around each of the end flaps, position an outer sleeve comprising the belt structure and the tread band in a coaxially centred position around the cylindrical carcass sleeve and shape the carcass sleeve according to a toroidal configuration through a radial expansion of the carcass structure, so as to cause the application thereof against a radially inner surface of the outer sleeve. After the building of the green tyre, a molding and vulcanization treatment is generally carried out in order to determine the structural stabilization of the tyre through vulcanization of the elastomeric compositions, as well as to impart a desired tread pattern on the tread band and at any distinguishing graphic signs at the sidewalls.

[0245] The Applicant has found that by virtue of the characteristics of the cross-linkable elastomer composition described herein, it is possible to provide a summer tyre with an increased wear resistance and better driving performance both on wet and dry roads.

[0246] EXPERIMENTAL PART

[0247] Methods of analysis and test methods

[0248] Glass transition temperature of the polymers by DSC

[0249] DSC glass transition temperature (Tg DSC) of the polymers was measured according to the method of ISO 22768:2006, modified with a heating rate of 10°C / min, as described below in detail.

[0250] The glass transition temperature of the polymers was determined by differential scanning calorimetry (DSC) using a DSC Mettler Toledo instrument (model 3+) under the following conditions. A test sample of weight between 5 mg and 20 mg was weighed and put without any treatment into a pan, the pan was sealed with cover and placed in the cell of the instrument set at 30 °C. The nitrogen gas flow was set at 80 ml / min. The sample was cooled to -120 °C at a cooling rate of 20 °C / min and then maintained at this temperature for 1 minute. To determine the glass transition temperature, the thermogram was recorded during the last heating step from -120 °C to +50 °C, at a heating rate of 10 °C / min. The glass transition temperature was measured at the inflection point of the DSC curve (i.e. at the minimum value of the first derivative of the DSC thermogram line) (see Figure 2). The ATg (absolute difference Tg DSC end - Tg DSC onset) was calculated by extrapolation of the Tg DSC end and Tg DSC onset temperatures from the DSC thermogram as illustrated in Figure 2.

[0251] The DSC thermal properties of the polymers are reported in Table 1 below:

[0252] Table 1

[0253] Polymer Tg (°C) ATg (°C)

[0254] SLR 4602 (sharp Tg SBR) -23 7

[0255] SLR 4630 (sharp Tg SBR) -24 9

[0256] SLR 3402 (sharp Tg SBR) -60 7

[0257] P91 (sharp Tg NR) -62 5

[0258] YB03 (sharp Tg BR) -90 5

[0259] PV1 (broad Tg SBR) -65 14

[0260] PV2 (broad Tg SBR) -60 12

[0261] PV3 (broad Tg SBR) -62 14

[0262] PV4 (broad Tg SBR) -53 14

[0263] PV5 (broad Tg SBR) -61 14

[0264] PS1 (broad Tg SBR) -61 14

[0265] PS2 (broad Tg SBR) -74 16

[0266] PS3 (broad Tg SBR) -60 15

[0267]

[0268] PS4 (broad Tg SBR) -60 34

[0269] Tg and ATg values were rounded to the unity. In the case of a digit with 0.5 decimal, it was rounded up to the next higher unit.

[0270] NMR analysis of the polymers

[0271] Total vinyl (Yall) and total styrene (Xall) content in the tested SBR polymers, as well as the cis / trans and vinyl content of the tested BR, were measured by 1H-NMR according to ISO 21561-1:20015, with an NMR spectrometer BRLIKER Avance (400 MHz) and a 5-mm dual probe, using CDCh (purity higher than 99.8%) as solvent containing 0.03 % of tetramethyl silane (TMS) as internal standard. The NMR results are reported in Table 2 below:

[0272] Table 2 Xall (wt%) Yall (%mol) Polymer

[0273] Aromatic vinyl units Vinyl units

[0274] PV1 (broad Tg SBR) 13.4 32.6

[0275] PV2 (broad Tg SBR) 14.0 33.2

[0276] PV3 (broad Tg SBR) 14.0 32.2

[0277] PV4 (broad Tg SBR) 20.6 31.8

[0278] PV5 (broad Tg SBR) 13.9 32.8

[0279] PS1 (broad Tg SBR) 7.7 43.0

[0280] PS2 (broad Tg SBR) 9.1 33.4

[0281] PS3 (broad Tg SBR) 8.0 46.7

[0282] PS4 (broad Tg SBR) 13.5 43.0

[0283] SLR 4602 (sharp Tg SBR) 21.7 62.4

[0284] SLR 4630 (sharp Tg SBR) 25.3 61.2

[0285] SLR 3402 (sharp Tg SBR) 15.0 30.5

[0286] Vinyl content (%wt) Cis Trans content (%mol) YB03 (sharp Tg BR) 12.0 88.0

[0287]

[0288] Glass transition temperature (Tn) of the compounds

[0289] The glass transition temperature, Tgof the compounds, determined on the peak value of the Tan Delta, was measured by dynamo-mechanical analysis (DMA). In particular, the vulcanized samples were analyzed with an EPLEXOR® 150 (GABO) device by carrying out a temperature sweep from -80 °C to +30 °C, with temperature increases of 2 °C / min, applying a dynamic tensile deformation of the 0.1 % at a frequency of 1 Hz. The specimens had the following dimensions: thickness 1 mm, width 10 mm, total length 46 mm, reference length 29 mm (represents the free length involved in the deformation while the two clamps block the ends of the specimen).

[0290] Scorch time

[0291] The scorch time was measured at 127 °C according to ISO 289-2:1994.

[0292] Rheometric analysis and Mooney viscosity

[0293] The cross-linkable elastomer compounds were subjected to MDR rheometric analysis (according to ISO 6502) using an Alpha Technologies rheometer type MDR2000. Mooney ML(1+4) viscosity was measured at 100 °C according to ISO Standard 289 / 1. Tests were carried out at 170 °C for 20 minutes at an oscillation frequency of 1.66 Hz (100 oscillations per minute) and an oscillation amplitude of ± 0.5°, measuring the time required to achieve an increase of two rheometric units (TS2) and the time required to reach 30% (T30), and 90% (T90) of the final torque value respectively. The maximum torque value MH and the minimum torque value ML were also measured.

[0294] Density: density was measured in accordance with ISO2781 method A with an automatic Densitron - Alpha Technologies.

[0295] Static mechanical properties were measured at 23 °C in accordance with standard ISO 37:2005. Specifically, load at different elongations (from 50% to 300% named in sequence Ca05 - Ca1 - Ca3), load at break (CR) and elongation at break (AR) were measured on samples of the elastomeric compounds, vulcanized at 170 °C for 10 minutes. Tensile tests were performed on ring-type specimens having a straight axis.

[0296] Dynamic mechanical properties were measured using a dynamic Instron device in compression-tension operation according to the following methods.

[0297] E’, E” moduli and Tan D

[0298] Samples of the raw elastomeric compounds, vulcanized at 170 °C for 10 minutes, having a cylindrical shape (length = 25 mm; diameter = 14 mm), pre-load compression up to 25% of longitudinal deformation compared to the initial length, kept at a preset temperature (+10 °C, +23 °C or +70 °C) for the entire test, were subjected to a dynamic sinusoidal deformation with an amplitude of ± 3.5% relative to the length under static pre-strain, at a frequency of 100 Hz.

[0299] The dynamic mechanical properties were expressed in terms of dynamic modulus of elasticity (E’), of tan delta (Tan D dissipation factor or hysteresis) and of loss compliance D” (grip index). The value of Tan D was calculated as the ratio between the viscous modulus (E”) and elastic modulus (E’). The value of D” was calculated as the ratio of Tan D and modulus E* (complex modulus E*=E’ + iE”).

[0300] Dynamic test by RPA (Rubber Process Analyzer)

[0301] This test was used to measures dynamic parameters of a cured compound and curing kinetic, Payne Effect (dG’) by Strain Sweep, G’ and Tan delta at 9% of strain, and torque. The procedure included the following steps and conditions:

[0302] - vulcanizing the sample for 10 minutes at 170 °C in dynamic conditions,

[0303] - waiting for 10 minutes, to ensure that the material recovered after vulcanization and reached the temperature of 70 °C,

[0304] - Strain Sweeping from 0.3% to 10% at 10Hz and 70 °C,

[0305] - Mechanical preconditioning of 100 cycles at 70 °C, 10Hz and 9% of strain,

[0306] - Dynamic Characterization at 70 °C, 10Hz at 9% and 3% of strain.

[0307] Abrasion resistance

[0308] Resistance to abrasion was determined according to DIN53516 by moving a test piece of the rubber compound across the surface of an abrasive sheet mounted on a revolving drum. It is expressed as volume loss in cubic millimetres. The lower was the loss, the better was the resistance to abrasion of the compound under test.

[0309] Examples

[0310] The following examples are provided for the purpose of further illustrating the invention and should not be construed as a limitation.

[0311] Example 1: elastomeric compositions with different elastomeric polymers and same plasticizer.

[0312] Purpose of the present example was to investigate the effect of different polymers, in particular of styrene-butadiene rubbers with a different microstructure, alone or blended, on the performance of the corresponding vulcanized compound (grip, rolling resistance and wear). Comparative compositions included conventional random SBRs, alone as in Ex. 1A or blended as in Ex. 1 C, with uniform Tg along polymer chains i.e. in which segments were absent, and a sharp DSC Tg profile (for brevity “sharp Tg” polymers).

[0313] Inventive composition comprised a particular SBR with 1stand 2ndsegments with a varying Tg along the chains and a flattened DSC Tg profile (for brevity “broad Tg” polymers). Comparative and inventive compositions and the corresponding compounds were prepared. The ingredients and their amounts are listed in the following Table 3:

[0314] Table 3

[0315] Ex. 1A Comp Ex. 1B Inv Ex. 1C Comp SLR 3402 (sharp Tg SBR) 100 — 36.85 PV5* (broad Tg SBR) — 100 (105) —

[0316] SLR 4602 (sharp Tg SBR) — — 36.85 YB03 (sharp Tg BR) — — 26.30 K 160 silica 105 105 105 TESPD / carbon black 1:1 14.7 14.7 14.7 Zinc salts 2.3 2.3 2.3 Stearic acid 1.75 1.75 1.75 6PPD 4.0 4.0 4.0 TMQ 2.1 2.1 2.1 Wax 2.45 2.45 2.45 Oil 1 5 — 5 Resin 1 29.9 29.9 29.9 Resin 2 18.1 18.1 18.1 Resin 3 14.6 14.6 14.6 Zinc neodecanoate / silica

[0317] 4.1 4.1 4.1 50 / 50

[0318] Isobutyl TUADS® 0.35 0.35 0.35 CBS 3.6 3.6 3.6

[0319]

[0320] Sulfur 1.6 1.6 1.6 in which * extended with 5 phr of TDAE oil,

[0321] in round brackets phr of extended polymer (dry polymer + oil) are reported.

[0322] SLR 3402 was a conventional partially coupled end chain functionalized random solution Styrene Butadiene Rubber (S-SBR) by Synthos Group with a styrene and vinyl content of about 15 (wt%) and 30 (%mol) respectively, with a Tg DSC of about -60 °C, an absolute difference Tg DSC end - Tg DSC onset of about 7 °C (“sharp Tg” polymer) and weight average molecular weight Mw of about 24,1 (104g / mol).

[0323] PV5 was a functionalized and branched styrene butadiene rubber, having a segmented microstructure, a Tg DSC of about -61 °C, an absolute difference Tg DSC end - Tg DSC onset of about 14 °C (“broad Tg” polymer), weight average molecular weight Mw of about 37.8 (104g / mol), comprising first and second segments, characterized by Y2-Y1 (difference of aliphatic vinyls between the segments) of about 37 (mol %), X2-X1 (difference of aromatic vinyls between the segments) of about 5 (wt %), total amount of bound styrene of about 14 (wt %), and total amount of vinyl unit of about 33 (mol %). This polymer corresponded to polymer P5 of the International Patent applications PCT / EP2024 / 061518 herein incorporated by reference.

[0324] SLR 4602 was a conventional random styrene butadiene rubber by Synthos Group with a styrene content of about 22% (wt%) and a vinyl content on the diene portion of about 62 mol%, with a Tg DSC of about -23 °C, an absolute difference Tg DSC end - Tg DSC onset of about 7 °C (“sharp Tg” polymer) and weight average molecular weight Mw of about 22.5 (104g / mol).

[0325] YB03 was a butadiene rubber by Asahi Kasei, having a Tg DSC of about -90 °C, an absolute difference Tg DSC end - Tg DSC onset of about 5 °C (“sharp Tg” polymer) and a weight average molecular weight of about 32 (104g / mol).

[0326] K 160 was silica from rice husk by Wilmar.

[0327] TESPD I carbon black was a 1:1 admixture of Bis Triethoxysilylpropyl Disulfide Silane and of N330 carbon black JH-Si75C by Birla Group.

[0328] Zinc salts by PURUS.

[0329] Stearic acid was vegetal stearic acid by Undesa.

[0330] TMQ was tetramethyl-1,4-benzoquinone by Lanxess.

[0331] 6PPD was phenyl-p-phenylenediamine by Flexsys.

[0332] Wax was RIOWAX BN01 a paraffin wax by SER S.p.A..

[0333] Oil 1 was NYTEX 4700 (oil), a high viscosity Naphthenic Black Oil by Nynas.

[0334] Resin 1 was STAYBELITE™ ESTER 3-E, a liquid triethylene glycol ester of hydrogenated gum rosin resin by Synthomer with a Tg of about -19 °C and a Tm of less than about 15 °C. Resin 2 was KRISTALEX F 85, an alpha-methyl styrene thermoplastic resin by Synthomer. having a softening point (Tm) of about from 80 °C to 90 °C, a Tg DSC of about 42 °C.

[0335] Resin 3 was HT-100 (C5 / C9 partially hydrogenated), a copolymerized hydrocarbon resin by Hanwha, having a Tm of about from 99 °C to 111 °C, a Tg DSC of about 58 ± 4 °C. Zinc neodecanoate / silica 50 / 50 was a 1:1 admixture of Zinc neodecanoate and silica by Rhein Chemie.

[0336] ISOBUTYL TUADS® was Isobutyl Thiuram Disulfide, an accelerator and vulcanizing agent by RTVanderbilt.

[0337] CBS was (N-cyclohexyl-2-benzothiazolesulfenamide), a sulfenamide type accelerator by Lanxess.

[0338] Sulfur was soluble sulfur (Ss) by Zolfoindustria (Italy).

[0339] Preparation of the elastomeric compounds

[0340] The above compositions were compounded in a standard two-step compound process by kneading in an internal lab mixer (Banbury rotor type) with a total chamber volume of 1100 cm3. The first mixing step (step 1) was performed at an initial temperature of 40 °C. After adding the polymer, the filler, and all other ingredients but the curing system, the rotor speed of the internal mixer was set, in order to reach a temperature between 145 °C and 150 °C, and kept at that temperature for 4 min., so that the silanization reaction could complete. Total mixing time for the first step was 2’30”. After dumping the compound, the mixture was cooled down and stored before adding the curing system in the second mixing step. The second mixing step (step 2) was carried out on the compound from the first mixing step for a total time of 2’15”, at an initial temperature of 50 °C, in the same equipment, after addition of sulfur as vulcanizing agent, ISOBUTYL TUADS® and CBS as accelerators.

[0341] Compounds properties

[0342] Table 4 below set out the properties of the compounds prepared as reported above from the compositions of Ex. 1A, 1B and 1C, measured according to the methods previously described:

[0343] Table 4 (curing 10 min at 170 °C)

[0344] Parameter Method / conditions Unity Ex.1A Ex.1B Ex.1C Comp. Inv. Comp.

[0345] Total oils (phr) 5.0 5.0 5.0 Total resins (phr) 62.6 62.6 62.6 Scorch time 127 °C min. s 32 37 35 Mooney ML (1+4) 100 °C UM 67 78 53 Density ISO2781 method A g / cm31.222 1.224 1.221 Ca0.5 Ring tensile test, 23° C MPa 1.3 1.4 1.3 Ca1 MPa 1.9 2.2 1.9 Ca3 MPa 7.8 9.6 7.4 CR MPa 18.1 17.3 16.0 AR % 611 514 580 Volume Loss Abrasion DIN53516, 1 Kg mm362 78 75

[0346] Tg (compound) DMA °C -29 -23 -23 ML RPA 70 °C; 10 Hz dN m 3.2 3.4 2.7 MH dN m 21.1 17.3 20.8

[0347]

[0348] T30 min 2.5 2.7 2.4 T60 min 2.86 3.11 2.75 T90 min 4.6 5.3 4.4 TS2 min 1.8 2.1 1.2 d G' (0.4-10) MPa 1.9 1.1 2.1 G' (9%) MPa 1.8 1.5 1.8 Tan Delta (9%) 0.158 0.151 0.168 E' MPa 11.7 12.0 12.6 D" (wet grip) +10 °C 100 / M Pa 3.8 3.9 3.6 Tan Delta 0.608 0.686 0.641 E' MPa 9.3 9.2 9.7 D" (dry grip) +23 °C 100 / M Pa 4.0 4.4 4.1 Tan Delta 0.446 0.507 0.486 E' MPa 5.6 5.2 5.5 D" +70 °C 100 / M Pa 3.3 3.5 3.5

[0349]

[0350] Tan Delta 0.190 0.189 0.201 n which D” represented the grip index.

[0351] The performance of the inventive compound of Ex. 1B comprising as the only polymer a “broad Tg” polymer was evaluated in comparison with the comparative compounds of Ex.

[0352] 1A and 1C comprising “sharp Tg” polymers, having the three compounds a similar Tg and the same plasticizer.

[0353] As can be seen from Table 4 above and from the graphs of Figure 4 showing the plots of wet grip (WG - 4A), dry grip (DG - 4B) (the higher the better) and RR (40 - the lower the better) of the compounds of Ex. 1A, 1B and 10, the inventive compound of Ex. 1B had: - the best grip performance both at low T (D” at +10 °C predictive of traction on wet surfaces) and high T (D” at +23 °C predictive of traction on dry surfaces);

[0354] - equal (Volume loss Ex. 1B vs Ex. 10) or predictable slightly worse (Volume loss Ex. 1B vs Ex. 1 A) but still acceptable abrasion, since comparison composition 1A was designed to result in a low Tg compound with more mileage;

[0355] - better (Tan D +70 °C Ex. 1B vs Ex. 10) or comparable (Tan D +70 °C Ex. 1B vs Ex. 1A) rolling resistance;

[0356] - static mechanical properties and processability in line with the comparative compounds.

[0357] Example 2: elastomeric compositions with different plasticizers

[0358] Purpose of the present example was to investigate the effect of different plasticizers, in particular the influence of different resins and oils, in different amounts, on the performance of the corresponding vulcanized compound (grip, rolling resistance and wear).

[0359] Reference composition of Ex. 2A was a typical composition for summer use including conventional random SBRs and NR, with uniform Tg along polymer chains i.e. segments were absent, and a sharp DSC Tg profile.

[0360] Inventive compositions comprised the peculiar SBR with 1stand 2ndsegments in the chains with a varying Tg along the chains and flattened DSC Tg profile (broad Tg polymer), alone as in Ex. 2B to Ex. 2E or blended with a conventional NR as in Ex 2F. Reference and inventive compositions and the corresponding compounds were prepared. The ingredients and their amounts are listed in the following Table 5:

[0361] Table 5 (phr)

[0362] Ex. 2A REF Ex. 2B Ex. 2C Ex 2D Ex. 2E Ex. 2F SLR 3402 (sharp Tg

[0363] 47.1 — — — — — SBR)

[0364] SLR 4630* (sharp Tg

[0365] 47.0 (64.6) — — — — — SBR)

[0366] P91 (sharp Tg NR) 5.9 — — — — 23.6

[0367] 100 100 100 100 76.4 PV5 (broad Tg SBR) —

[0368] (105) (105) (105) (105) (80.2) TESPD / carbon black

[0369] 13.5 15.8 15.8 15.8 15.8 15.9 1:1

[0370] Silica 96.5 — — — — — Silica (K160-rice husk

[0371] — 105 105 105 105 106 silica)

[0372] Stearic acid 1.8 1.8 1.8 1.8 1.8 1.8 Wax 2.1 2.5 2.5 2.5 2.5 2.5 Oil 2 — 11.7 11.7 — — — Oil 3 — — — — 11.7 — Oil 4 4.7 — — — — — Oil 5 11.8 — — — — — Resin 1 5.9 17.5 17.5 29.2 17.5 31.6 Resin 2 17.6 14.6 — 14.6 14.6 14.7 Resin 3 — 14.6 29.2 14.6 14.6 14.7 Resin 4 4.7 — — — — — SureMix® CO2 — 5.6 5.6 5.6 5.6 5.6 TMQ 2.0 2.1 2.1 2.1 2.1 2.1 6PPD 3.8 4.0 4.0 4.0 4.0 4.0 Zinc neodecanoate

[0373] — 4.1 4.1 4.1 4.1 4.1 / silica 50 / 50

[0374] Zinc salts 2.4 — — — — — Zinc octoate 75 2.7 — — — — — Isobutyl TUADS® 0.35 0.35 0.35 0.35 0.35 0.35 CBS 3.5 3.6 3.6 3.6 4.0 3.6

[0375]

[0376] Sulfur 1.6 1.6 1.6 1.6 1.8 1.6 in which * extended with 17,6 phr of TDAE oil.

[0377] SLR 4630 (SBR) was a conventional partially Si-coupled random solution Styrene Butadiene Rubber (S-SBR) by Synthos Group with a styrene and vinyl content on the diene portion of about 25.3 (wt%) and 61.2 (mol%) respectively, with a Tg DSC of about -24 °C, an absolute difference T g DSC end - Tg DSC onset of about 9 °C (“sharp T g” polymer) and weight average molecular weight Mw of about 53 (104g / mol).

[0378] P91 (NR) was a natural rubber by Pt Kirana Musi Persada (SFN) having a Tg DSC of about -62 °C, an absolute difference Tg DSC end - Tg DSC onset of about 5 °C (“sharp Tg” polymer). TESPD I carbon black was a 1:1 admixture of Bis Triethoxysilylpropyl Disulfide Silane and of N330 carbon black JH-Si75C by Birla Group. Silica was Zeosil 1165 MP by Solvay.

[0379] Oil 2 was paraffinic oil MES (Mild Extract Solvated) CLEMATIS MS by ENI.

[0380] Oil 3 was soyabean oil by Wilmar.

[0381] Oil 4 was tris(2-ethylhexyl)phosphate (TOF) by Lanxess.

[0382] Oil 5 was Vivatec 500, TDAE by H&R.

[0383] Resin 4 was a styrene-indene hydrocarbon resin, commercially available as Novares TL 90 by Rain Carbon, having a softening point (Tm) of about from 85 to 95 °C, and a Tg of about from 35 to 45 °C.

[0384] SureMix® CO2 was a processing aid by Polymer Solution Group (PSG).

[0385] Zinc salts by Huatai (Purus).

[0386] Zinc octoate 75 was zinc octoate by Schill & Seilacher; and the other ingredients were as reported above.

[0387] Preparation of the elastomeric compounds

[0388] The corresponding elastomeric compounds were prepared as described in Example 1. Compounds properties

[0389] Table 6 below set out the properties of the compounds prepared as reported above from the compositions of Ex. 2A to 2F measured according to the methods previously described:

[0390] Table 6 (curing 10 min at 170 °C)

[0391] Method

[0392] Parameter / conditio Unity Ex.2A Ex.2B Ex.2C Ex.2D Ex.2E Ex.2F ns

[0393] Ref. Inv. Inv. Inv. Inv. Inv. Total oils

[0394] 34.1 16.7 16.7 5.0 16.7 3.8 (phr)

[0395] Total resins

[0396] 28.2 46.7 46.7 58.4 46.7 61.0 (Phr)

[0397] Scorch time 127 °C min. s 37 47 47 43 45 444 Mooney

[0398] 100 °C UM 76 73 76 79 74 61 ML(1+4)

[0399] Density g / cm31.211 1.221 1.000 1.229 1.000 1.231

[0400] Ring

[0401] tensile

[0402] Ca0.5 MPa 1.1 1.1 1.1 1.2 1.1 1.1 test, 23°

[0403] C

[0404] Ca1 MPa 1.8 1.8 1.8 1.9 1.8 1.8 Ca3 MPa 7.7 8.7 8.7 9.0 8.4 8.2 CR MPa 17.4 18.1 18.0 18.5 18.3 18.1 AR % 560 573 562 577 600 634 Abrasion

[0405] Volume

[0406] DIN5351 mm383 69 74 53 71 65 Loss

[0407] 6, 1 Kg

[0408] Tg DMA °C -24 -29 -29 -26 -32 -27

[0409]

[0410] (compound) RPA 70

[0411] ML dN m 3.7 3.1 3.3 3.2 3.2 2.5 °C; 10 Hz

[0412] MH dN m 21.6 17.8 17.6 19.0 17.7 18.1 T30 min 2.9 3.6 3.7 3.5 3.6 3.1 T60 3.6 4.3 4.4 4.2 4.2 3.7 T90 min 5.8 6.9 6.9 6.9 6.8 6.7 d G' (0.4- MPa 2.7 1.5 1.5 1.5 1.5 1.7 10)

[0413] G' (9%) MPa 2.0 1.5 1.6 1.6 1.5 1.6 Tan Delta

[0414] 0.187 0.171 0.173 0.169 0.169 0.178 (9%)

[0415] E' MPa 11.5 10.8 10.8 11.6 10.2 11.4

[0416] 100 / MP

[0417] D" (wet grip) +10 °C 3.9 4.1 4.1 4.0 4.2 4.0 a

[0418] Tan Delta 0.610 0.600 0.604 0.655 0.573 0.662 E' MPa 8.9 8.5 8.6 9.3 8.2 8.9

[0419] 100 / MP

[0420] D" (dry grip) +23 °C 4.1 4.3 4.3 4.3 4.4 4.5 a

[0421] Tan Delta 0.440 0.441 0.447 0.491 0.429 0.493 E' MPa 5.2 5.1 5.1 5.2 5.0 5.1

[0422] 100 / MP

[0423] D" +70 °C 3.5 3.6 3.7 3.6 3.8 3.9 a

[0424]

[0425] Tan Delta 0.190 0.192 0.195 0.194 0.195 0.206

[0426] The performance of the inventive compounds of Ex. 2B to Ex. 2F comprising as the only (2B to 2E) or main (2F) polymer the same “broad Tg” polymer and varying amounts of oils and resins, was evaluated in comparison with the reference compound of Ex. 2A comprising conventional “sharp Tg” polymers, having all the compounds under test a similar Tg.

[0427] Figure 5 shows the radar chart of grip (+10 °C, WG wet grip and at +23 °C, DG dry grip), rolling resistance (RR) and wear (WR) of the compounds of Ex. 2A and Ex. 2B (key: continuous line Ex. 2A reference; mixed point and hatch line Ex. 2B inventive).

[0428] As can be seen from the radar chart, the compound of Ex. 2B had the best balance of overall performance, with an improvement in DG and WG parameters, an improved wear resistance (the higher the better, since WR is expressed in the radar chart as inversely proportional to the Volume Loss, weighted on the corresponding Ca3 value), with respect to that of reference Ex. 2A, while maintaining a RR comparable with that of Ex. 2A.

[0429] Moreover, as can be seen from the data of Table 6 above and from the graphs of Figure 6 showing the plots of grip (wet - 6A- and dry - 6B- the higher the better) and RR (60 - the lower the better) of the compounds of Ex. 2A to Ex. 2F:

[0430] - all the inventive compounds (Ex. 2B to Ex. 2F) showed an improved wet grip index in comparison with the reference compound of Ex. 2A; the inventive compound of Ex. 2E showed the best wet grip index (D” at +10 °C 4.2) but associated with a volume loss higher than Ex. 2D, anyway acceptable in comparison with the volume loss of the reference compound of Ex. 2A;

[0431] - all the inventive compounds (Ex. 2B to Ex. 2F) showed an improved dry grip index in comparison with the reference compound of Ex. 2A; the inventive compounds of Ex. 2E and Ex. 2F showed the best dry grip indexes (D” at +23 °C of 4.4 and 4.5 respectively vs 4.1 of the reference compound of Ex. 2A) associated in case of Ex. 2E with a volume loss higher than Ex. 2D, anyway acceptable in comparison with the volume loss of the reference compound of Ex. 2A and in case of Ex. 2F with a slightly higher RR;

[0432] - all the inventive compounds (Ex. 2B to Ex. 2F) showed an improved wear resistance in comparison with the reference compound of Ex. 2A; the inventive compound of Ex. 2D had the best performance in terms of wear resistance.

[0433] Overall, the best balance between static mechanical properties, RR, wear and wet grip was observed for the compound of Ex. 2D, having low oil and high resin contents.

[0434] Regarding the compound of Ex. 2F, having the lowest oil and highest resin content and a blend of a conjugated diene polymer (I) (“broad Tg” polymer) with a “sharp Tg” conventional polymer (NR) the performance was superior to the reference compound of Ex. 2A in terms of wear resistance, wet and dry grip but a little worse, even still acceptable, as rolling resistance.

[0435] All the inventive compounds (Ex. 2B to Ex. 2F) showed static mechanical properties better than the reference compound of Ex. 2A.

[0436] Example 3: elastomeric compositions with pure (no blend) polymers, same filler (silica) in superior amount.

[0437] Purpose of the present example was to investigate the effect of increased silica - a silica I polymer ratio higher than 1:1 was used - on the performance of the corresponding vulcanized compound (grip, rolling resistance and wear).

[0438] Comparison composition of Ex. 3A included a conventional “sharp Tg” random SBR (SLR3402), while the inventive composition of Ex. 3B the particular “broad Tg” conjugated diene polymer (PV5) having 1stand 2ndsegments in the chains with a varying Tg along the chains and a flattened DSC Tg.

[0439] Comparison and inventive compositions and the corresponding compounds were prepared. The ingredients and their amounts are listed in the following Table 7:

[0440] Table 7

[0441] Ex. 3A Ex. 3B

[0442] Comp. Inv.

[0443] SLR 3402 (sharp Tg SBR) 100 —

[0444] PV5 (broad Tg SBR) — 100 (105) Silica 115 115

[0445]

[0446] TESPD / carbon black 1:1 16.1 16.1 Wax 2.5 2.5

[0447] Oil 1 15 15

[0448] Resin 1 15 15

[0449] Resin 2 15 10

[0450] Resin 3 15 15

[0451] TMQ 2.2 2.2

[0452] 6PPD 4 4

[0453] Zinc neodecanoate / silica 50 / 50 3.5 3.5

[0454] ISOBUTYL TUADS® 0.6 0.6

[0455] MBTS 80 0.5 0.5

[0456] CBS 3.5 3.5

[0457]

[0458] Sulfur 1.4 1.4

[0459] in which

[0460] Silica was Ultrasil 700 by Evonik.

[0461] MBTS 80 was the accelerator Rhenogran® MBTS-80 by Rhein Chemie Additives (Lanxess Group), and the other ingredients were as reported above.

[0462] In the inventive composition, the amount of oil was increased to bring the Tg of the resulting compound closer to that of the reference compound.

[0463] Preparation of the elastomeric compounds

[0464] The corresponding elastomeric compounds were prepared as described in Example 1. Compounds properties

[0465] Table 8 below set out the properties of the compounds prepared as reported above from the compositions of Ex. 3A and Ex. 3B measured according to the methods previously described:

[0466] Table 8 (curing 10 min at 170 °C)

[0467] Parameter Method / conditions Unity Ex. 3A Ex. 3B Comp. Inv. Scorch time 127 °C min. s 18.6 26.1 Mooney ML (1+4) 100 °C UM 133 105 Density ISO2781 g / cm31.246 1.244 Ca0.5 Ring tensile test, 23° C MPa 1.9 1.6 Ca1 MPa 2.7 2.5 Ca3 MPa 10.4 10.7 CR MPa 14.2 15.0 AR % 408 418 Abrasion DIN53516, 1

[0468] Volume Loss mm355.1 68

[0469] Kg

[0470] Tg (compound) DMA °C -34 -30 ML RPA 70 °C; 10 Hz dN m 8.2 5.7 MH dN m 27.1 22.4 T30 min 1.8 2.0 T60 min 2.02 2.35 T90 min 3.0 3.7 TS2 min 1.5 1.0

[0471]

[0472] d G' (0.4-10) MPa 3.8 2.6 G' (9%) MPa 2.8 2.2 Tan Delta (9%) 0.190 0.195 E' MPa 17.2 15.1 D" 100 (wet grip) +10 °C 100 / MPa 2.4 2.9 Tan Delta 0.515 0.581 E' MPa 14.2 12.1 D" 100 (dry grip) +23 °C 100 / MPa 2.5 3.1 Tan Delta 0.405 0.456 E' MPa 9.7 7.6 D" 100 +70 °C 100 / MPa 2.0 2.6

[0473]

[0474] Tan Delta 0.207 0.210

[0475] The performance of the inventive compound of Ex. 3B comprising as the only polymer the same “broad Tg” polymer, was evaluated in comparison with the reference compound of Ex. 3A comprising as the only polymer a conventional “sharp Tg” polymer, having both the compounds under test a similar Tg.

[0476] As can be seen from the data of Table 8 above and from the graphs of Figure 7 showing the plots of grip (wet grip -7A- and dry grip - 7B- the higher the better) and RR (7C - the lower the better) of the compounds of Ex. 3A and Ex. 3B the best balance of properties was observed for the inventive compound of Ex. 3B, containing the “broad Tg” polymer, that against a greatly improved wet grip and dry grip performed a predictable worse but still acceptable abrasion, since comparison composition 3A was designed to result in a low Tg compound with more mileage, while maintaining a comparable rolling resistance.

[0477] Example 4: elastomeric compositions with different polymers (I) (no blends)

[0478] Purpose of the present example was to investigate the effect of styrene-butadiene rubbers with different microstructures on the performance of the corresponding vulcanized compounds (grip, rolling resistance and wear).

[0479] Inventive composition comprised three different SBR with 1stand 2ndsegments with a varying Tg along the chains and a flattened DSC Tg profile (for brevity “broad Tg” polymers). Inventive compositions and the corresponding compounds were prepared. The ingredients and their amounts are listed in the following Table 9:

[0480] Table 9

[0481] Ex. 4A Ex. 4B Ex. 4C Inv. Inv. Inv. PV1*(broad Tg SBR) — 100 (105) — PS1* (broad Tg SBR) — — 100 (105) PV5* (broad Tg SBR) 100 (105) — — K 160 silica 105 105 105 TESPD / carbon black 1 : 1 14.7 14.7 14.7 Zinc salts 2.3 2.3 2.3 Stearic acid 1.75 1.75 1.75

[0482]

[0483] 6PPD 4.0 4.0 4.0 TMQ 2.1 2.1 2.1 Wax 2.45 2.45 2.45 Resin 1 29.9 29.9 29.9 Resin 2 18.1 18.1 18.1 Resin 3 14.6 14.6 14.6 Zinc neodecanoate / silica 50 / 50 4.1 4.1 4.1 Isobutyl TLIADS® 0.35 0.35 0.35 CBS 3.6 3.6 3.6

[0484]

[0485] Sulfur 1.6 1.6 1.6 in which

[0486] * extended with 5 phr of oil;

[0487] PV1 was a functionalized and branched styrene butadiene rubber, having a segmented microstructure, a Tg DSC of about -65 °C, an absolute difference Tg DSC end - Tg DSC onset of about 14 °C (“broad Tg” polymer), weight average molecular weight Mw of about 50.55 (104g / mol), comprising first and second segments, characterized by Y2-Y1 (difference of aliphatic vinyls between the segments) of about 38 (mol %), X2-X1 (difference of aromatic vinyls between the segments) of about 2 (wt %); total amount of bound styrene of about 13% (wt%); total amount of vinyl unit of about 33 % (mol%). This polymer corresponded to polymer P1 of the International Patent applications PCT / EP2024 / 061518 herein incorporate by reference.

[0488] PS1 was a functionalized and branched styrene butadiene rubber, having a segmented microstructure, a Tg DSC of about -61 °C, an absolute difference Tg DSC end - Tg DSC onset of about 14 °C (“broad Tg” polymer), weight average molecular weight Mw of about 45.83 (104g / mol), comprising first and second segments, characterized by Y2-Y1 (difference of aliphatic vinyls between the segments) of about 8 (mol %), X2-X1 (difference of aromatic vinyls between the segments) of about 25 (wt %); total amount of bound styrene of about 8% (wt %); total amount of vinyl unit of about 43% (mol %); this polymer corresponded to polymer P1 of the International Patent applications PCT / EP2024 / 061544, herein incorporate by reference, and the other ingredients were as reported above.

[0489] Preparation of the elastomeric compounds

[0490] The corresponding elastomeric compounds were prepared as described in Example 1. Compounds properties

[0491] Table 10 below set out the properties of the compounds prepared as reported above from the compositions of Ex. 4A, Ex. 4B and Ex. 4C measured according to the methods previously described:

[0492] Table 10 (curing 10 min at 170 °C)

[0493] Parameter Method / conditions Unity Ex. 4A Ex. 4B Ex.4C Inv. Inv. Inv.

[0494]

[0495] Scorch time 127 °C min. s 23 18 20 Mooney ML (1+4) 100 °C UM 83 61 68 Density ISO2781 g / cm31.224 1.223 1.218 Ca0.5 Ring tensile test, 23° C MPa 1.4 1.3 1.3 Ca1 MPa 2.5 2.0 2.2 Ca3 MPa 9.8 8.1 8.9 CR MPa 18.6 17.8 17.8 AR % 600 626 575 Tg (compound) DMA °C -25 -25 -25 ML RPA 70 °C; 10 Hz dN m 3.7 3.0 3.3 MH dN m 16.0 16.7 16.6 T30 min 2.1 1.8 1.9 T60 min 2.5 2.1 2.2 T90 min 4.2 3.5 4.1 TS2 min 1.9 1.6 1.6 d G' (0.4-10) MPa 1.0 1.4 1.3 G' (9%) MPa 1.4 1.5 1.5 Tan Delta (9%) 0.158 0.184 0.173 E' MPa 12.6 12.9 12.7 D" 100 (wet grip) +10 °C 100 / M Pa 3.7 3.5 3.6 Tan Delta 0.704 0.642 0.654 E' MPa 9.5 10.0 9.9 D" 100 (dry grip) +23 °C 100 / M Pa 4.3 3.9 4.0 Tan Delta 0.527 0.477 0.486 E' MPa 5.2 5.7 5.6 D" 100 +70 °C 100 / M Pa 3.7 3.6 3.7

[0496]

[0497] Tan Delta 0.200 0.212 0.218

[0498] The performance of the inventive compounds of Ex. 4A, Ex. 4B and Ex. 4C comprising as the only polymer “broad T g” polymers having a Tg DSC not higher than -40°C, was evaluated. As can be seen from Table 10 above and from the graphs of Figure 8 showing the plots of grip (wet grip -8A- and dry grip- 8B- the higher the better) and RR (8C - the lower the better) of the compounds of Ex. 4A, Ex. 4B and Ex. 4C, the compound containing polymer PV5 (Ex. 4A) performed better than the compounds of Ex. 4B and Ex. 4C, respectively comprising PV1 and PS1, in terms both of dry grip, wet grip, and rolling resistance.

[0499] Example 5

[0500] In this example, the inventive composition of Ex. 4A and the reference composition of Example 2A, reported for convenience in the following Table 11

[0501] Table 11

[0502] Ex. 4A Ex. 2A (Inventive) (Reference) P91 (sharp Tg NR) — 5.9 SLR3402 (sharp Tg SBR) — 47.1 SLR4630 (sharp Tg SBR) — 47.0 (64.6) PV5* (broad Tg SBR) 100 (105) — Silica (K160-rice husk silica) 105 —

[0503]

[0504] Silica (Zeosil 1165 MP) — 96.5 TESPD 1 carbon black 1 : 1 14.7 13.5 Zinc salts 2.3 2.35 Stearic acid 1.75 1.8 6PPD 3.85 3.8 TMQ 2.1 2.0 Wax 2.45 2.1 Oil 4 — 4.7 Oil 5 — 11.8 Resin 1 29.9 5.9 Resin 2 18.1 17.6 Resin 3 14.6 — Resin 4 — 4.7 Zinc neodecanoate / silica 50 / 50 4.1 — Zinc octoate 75 — 2.7 Isobutyl TLIADS® 0.35 0.35 CBS 3.6 3.5

[0505]

[0506] Sulfur 1.6 1.6 extended with 5 phr of oil

[0507] were directly compared in terms of tan delta, to evaluate the performance working range of said compounds, observable from the curves of Figure 3.

[0508] Indeed, Figure 3 shows tan delta curves of the elastomeric compounds of Ex. 5 (continuous line Ex. 2A reference; mixed point and hatch line Ex. 4A inventive) at increasing temperatures. From the graph, it appeared that the conjugated polymer (I) provided for a significant broadening of the peak and increase of the Tan D values at temperatures from about -10 °C to +30 °C, namely mainly in the operating range of summer tyres. This trend was predictive of better grip under both wet and dry conditions for the compound prepared from the inventive composition of Example 4A.

Claims

CLAIMS1. An elastomeric composition comprising:- 100 phr of one or more elastomeric polymers comprising one or more conjugated diene polymer (I), said conjugated diene polymer (I) comprising bound conjugated diene monomer units (Y) and, optionally, bound aromatic vinyl monomer units (X) and including at least a first polymer segment and at least a second polymer segment, wherein:Y1 (mol %) is the amount of vinyl unit in the bound conjugated diene monomer unit of the first polymer segment,Y2 (mol %) is the amount of vinyl unit in the bound conjugated diene monomer unit of the second polymer segment,X1 (wt %) is the amount of bound aromatic vinyl monomer unit in the first polymer segment,X2 (wt %) is the amount of bound aromatic vinyl monomer unit in the second polymer segment,in whichX1 is different from X2, and / orY1 is different from Y2,wherein said conjugated diene polymer (I) has a Tg DSC measured according to the method of ISO 22768:2006 modified with a heating rate of 10 °C / min, not higher than -40 °C, preferably not higher than -50 °C;- 20 phr to 80 phr of a plasticizing admixture comprising:15 phr to 50 phr of at least a solid resin,5 phr to 50 phr of at least a liquid resin,0 phr to 25 phr of at least an oil,0 phr to 30 phr of at least a liquid polymer;- 10 phr to 150 phr of at least a reinforcing filler; and- at least 0.5 phr of at least a vulcanizing agent.

2. The elastomeric composition according to claim 1, wherein the one or more conjugated diene polymer (I) is in an amount of at least 25 phr, 30 phr, 40 phr, 50 phr or 60 phr, preferably of at least 70 phr, 75 phr or 80 phr, more preferably of at least 90 phr, even more preferably of at least 95 phr, most preferably is the only elastomeric polymer of the elastomeric composition.

3. The elastomeric composition according to claim 1 or 2, wherein in said conjugated diene polymer (I):Y2 -Y1 (mol %) is from 15% to 50% and, if bound aromatic vinyl monomer units are present, |X1 - X2| (wt %) is at most 5%; orY2 -Y1 (mol %) is from 0 mol % to 45 mol % and X2 - X1 (wt %) is higher than 5 wt%.

4. The elastomeric composition according to any one of the previous claims wherein the conjugated diene polymer (I) comprises 1,3-butadiene and / or isoprene as bound conjugated diene monomer units (Y) and, if present, styrene as bound aromatic vinyl monomer units (X).

5. The elastomeric composition according to any one of the previous claims wherein, in the conjugated diene polymer (I), the difference Y2 -Y1 (mol %) between the amount of vinyl monomer unit in the second polymer segment Y2 (mol %) and the amount of vinyl monomer unit in the first polymer segment Y1 (mol %) is from 15% to 50%, preferably from 20 mol % to 45 mol %, more preferably from 25 mol % to 45 mol %.

6. The elastomeric composition according to claim 5 wherein, in the conjugated diene polymer (I), bound aromatic vinyl monomer units are present and the absolute value of the difference |X1 - X2| (wt %) between the amount of bound aromatic vinyl monomer unit in the second polymer segment X2 (wt %) and the amount of bound aromatic vinyl monomer unit in the first polymer segment X1 (wt %) is at most 5% and at least 2 wt %.

7. The elastomeric composition according to any one of the previous claims wherein, in the conjugated diene polymer (I), bound aromatic vinyl monomer units are present, the difference Y2 -Y1 (mol %) between the amount of vinyl monomer unit in the second polymer segment Y2 (mol %) and the amount of vinyl monomer unit in the first polymer segment Y1 (mol %) is from 0 mol % to 45 mol %, preferably from 5 mol % to 35 mol %, more preferably from 5 mol % to 20 mol % and, the difference X2 - X1 (wt %) between the amount of bound aromatic vinyl monomer unit in the second polymer segment X2 (wt %) and the amount of bound aromatic vinyl monomer unit in the first polymer segment X1 (wt %) is higher than 5 wt %, preferably is between 5 wt % and 35 wt %, more preferably between 10 wt % and 30 wt %.

8. The elastomeric composition according to any one of previous claims wherein:the weight average molecular weight (Mw) of the conjugated diene polymer (I) measured by gel permeation chromatography (GPC) is from 300,000 g / mol to 1,350,000 g / mol, preferably from 400,000 g / mol to 1,000,000 g / mol, more preferably from 400,000 g / mol to 700,000 g / mol;the number average molecular weight (Mn) of the conjugated diene polymer (I) measured by gel permeation chromatography (GPC) is at least 100,000 or 170,000 g / mol, preferably at least 190,000 g / mol, more preferably at least 200,000 g / mol and / or at most 1 ,000,000 or 800,000 g / mol, preferably at most 500,000 g / mol, more preferably at most 450,000 g / mol; andthe polydispersity index Mw / Mn of the conjugated diene polymer (I) is at least 1.2 and at most 2.5, preferably at least 1.3, more preferably at least 1.4 and at most 2.4, more preferably at most 2.2, even more preferably at most 2.0.

9. The elastomeric composition according to any one of previous claims wherein the glass transition temperature Tg DSC of the conjugated diene polymer (I) is from -80 °C to -50 °C, preferably from -75 °C to -50 °C, more preferably from -65 °C to -55 °C measured according to the method of ISO 22768, modified with a heating rate of 10 °C / min.

10. The elastomeric composition according to any one of previous claims wherein the absolute difference between the extrapolated Tg DSC end temperature and the extrapolated Tg DSC onset temperature of the conjugated diene polymer (I) is lower than 35 °C, than 30 °C, than 20 °C or than 15 °C and / or higher than 10 °C or than 12 °C or than 13 °C.

11. The elastomeric composition according to any one of previous claims comprising from 40 phr to 75 phr, preferably from 55 phr to 70 phr of the plasticizing admixture.

12. The elastomeric composition according to any one of previous claims comprising a plasticizing admixture including20 phr to 40 phr of at least a solid resin,10 phr to 40 phr of at least a liquid resin,0 to 20 phr of at least an oil,0 to 25 phr of at least a liquid polymer.

13. An elastomeric compound obtainable from the elastomeric composition of any one of claims 1 to 12, the elastomeric compound preferably having, after vulcanization, a glass transition temperature Tg measured by dynamo-mechanical analysis (DMA) from -35 °C to -15 °C.

14. A tyre for vehicle wheel comprising the elastomeric compound according to claim 13, preferably at least in the tread band.

15. The tyre of claim 14 which is a summer tyre.

Images