RU2320495C2 - Highly efficient tire for vehicle wheels - Google Patents

Abstract

FIELD: transport engineering; tire industry; highly efficient tires.

SUBSTANCE: proposed tire for vehicle wheels includes carcass structure of toroidal shape whose opposite side edges are coupled by corresponding right-hand side and left-hand side bead wires to form corresponding beads; breaker structure applied in outer relative to radius position relative to said carcass structure: tread band radially applied to breaker structure; at least one layer of cross-linked elastomer material applied in inner relative to radius position relative to said tread band; pair of side strips applied from side to opposite sides relative to carcass structure; at least one layer of cross-linked elastomer material has following characteristics: dynamic modulus of elasticity E¹ measured at 70°C not lower than 20 MPa, preferably, from 25 MPa to 50 MPa; ratio between modulus of elasticity at extension at 100% elongation (MIOO) and modulus of elasticity at extension at 10% elongation (MIO) not lower than 1.5, preferably, from 2 to 5. One layer of cross-linked elastomer material is preferably laid between tread band and breaker structure. Invention provides better characteristics of tire during operation at high driving speed and/or extreme driving conditions - rigid steering, simultaneously with satisfactory behavior at normal driving conditions - soft steering.

EFFECT: improved service characteristics of tire.

50 cl, 4 ex, 5 tbl, 2 dwg

Description

The present invention relates to a tire for vehicle wheels and, in particular, to a high performance tire.

In the industry of producing tires for vehicle wheels, in particular high-performance tires, such as, for example, tires for high-power vehicles, or mainly tires intended for operation at high operating speeds and / or extreme driving conditions; at the same time, there is an increasing need to provide even higher performance in terms of, for example, stability of a tire assembly, tire grip, stability of control, stability of movement when cornering, and ease of driving.

These tires, which are usually referred to as “HP” or “UHP” (“high performance” or “over high performance”) tires, are in particular those belonging to the “V” or “Z” classes, which are respectively designed for maximum speeds from 210 km / h to 240 km / h and higher than 240 km / h.

Typically, tires for vehicle wheels include a carcass structure substantially made of one or more carcass layers of substantially toroidal shape, the edges of which are axially opposite sides are in contact with corresponding circular rigid annular reinforcing elements, typically referred to as so-called " bead wires ”or“ bead wire rings ”.

A belt structure is applied to the frame structure in a radial external position, including one or more closed-loop belt tapes and essentially made of textile or metal cords, suitably oriented with respect to each other and with respect to the cords belonging to adjacent layers frame.

In the radial external position of the belt structure, a tread band is formed, which usually consists of a band of elastomeric material of suitable thickness.

In conclusion, a pair of sidewalls is made on opposite sides of the tire, each of these sidewalls covering a part of the side of the tire enclosed between the so-called shoulder region located near the corresponding lateral edge of the tread band and the so-called bead located in accordance with the corresponding bead wire.

In high performance tires, in order to provide high performance at high operating speeds and / or under extreme driving conditions in a radial outer position with respect to the tread band, at least one layer of elastomeric material having a small thickness and high strength properties can be made (in features by tensile modulus and tensile stress).

The mechanical properties of the above layer can be increased by increasing the crosslink density of the elastomeric material by using a large amount of sulfur, or by using a large amount of soot or a very fine and structured soot, which has a high reinforcing ability. However, the above methods for improving mechanical properties can lead to a number of disadvantages.

For example, the use of large amounts of sulfur can cause a noticeable reversal phenomenon, which leads to modifications in tire performance during use. On the other hand, it is known that carbon black gives noticeable hysteretic properties to the elastomeric composition, namely an increase in dissipative heat under dynamic conditions, which leads to an increase in tire rolling resistance. In addition, a large amount of soot significantly increases the viscosity of the non-crosslinked gray elastomeric material and, therefore, has a negative effect on its processability and extrudability.

Therefore, other methods are usually applied to improve the mechanical properties of the above layer under the tread band. Typically, the elastomeric material is reinforced with organic fibers such as, for example, polyamide fibers (especially aromatic polyamide fibers, known as “aramid fibers”), polyester fibers or polyolefin fibers.

For example, WO 00/24596 discloses a tire with an elastomeric intermediate layer of a component located between the tread band and the belt layers, in which the elastomeric intermediate layer is made of fiber reinforced material. The specified elastomeric intermediate layer can be reinforced with short reinforcing fibers, such as, for example, aramid fibers (for example, Kevlar ^® sludge), to improve their elastic modulus along with other mechanical characteristics.

European patent application EP 691218 discloses a tire component for a pneumatic tire including a reinforced vulcanizable composition, said composition comprising a vulcanizable elastomeric matrix material having an effective reinforcing amount distributed in it of partially oriented fibers having a modulus of less than 10 GPa, preferably less than 6 GPa. As an alternative embodiment, the tire component can be strengthened with a mixture of partially oriented fibers and fibrillated slurry fibers (e.g., Kevlar ^® sludge). It should be noted that the aforementioned vulcanizable composition is particularly suitable for the groove layer of a pneumatic tire.

Therefore, there is a need to create a tire for vehicle wheels, in particular a highly efficient tire that combines improved performance under harsh driving conditions with good maneuverability and ease of use under normal driving conditions (i.e., soft steering).

As noted, the tire, especially when used at high operating speeds and / or under extreme driving conditions (i.e., hard handling), is subjected to significant forces that are directed both transversely and longitudinally, and therefore, the tire needs to be reinforced in both directions.

It was noted that the above combination of properties cannot be achieved when the tire is reinforced with a layer located under the tread band made of an elastomeric material containing aramid fibers. First, aramid fibers exhibit remarkable anisotropic behavior, namely, they are essentially oriented in the direction of shear forces acting on the extrusion and calendering of the unvulcanized elastomeric material to form a layer (usually called the "calendering direction") so as to give the tire a substantially longitudinal reinforcement, namely, amplification essentially in the circular direction of the tire. Moreover, the reinforcement imparted by the aramid fibers to the elastomeric material remains substantially unchanged when the load to which the material is subjected increases.

On the other hand, an increase in the number of aramid fibers added to the elastomeric material to increase the mechanical properties does not produce the desired effect. In fact, due to poor dispersion, a large number of aramid fibers can degrade the processability of unvulcanized elastomeric material and, therefore, the quality of the finished product both in terms of mechanical properties and in appearance. This can cause cracking and delamination of the reinforcing layer from other structural components of the tire either during the production process or during use of the tire.

It should be noted that tires can be obtained showing improved performance during use at high operating speeds and / or under extreme driving conditions (i.e., hard driving) coupled with satisfactory behavior under normal driving conditions (soft driving), especially the convenience and maneuverability when applying a radial internal position with respect to the tread band of at least one layer of gray crosslinked elastomeric material having a dynamic module (E ) the elasticity measured at 70 ° C is not lower than 20 MPa and the ratio between the tensile modulus at 100% elongation (M100) and the tensile modulus at 10% elongation (M10) is not lower than 1, 5.

In accordance with a first aspect, the present invention relates to a tire for vehicle wheels, including:

a frame structure formed essentially in a toroidal configuration, the opposite side edges of which are connected with the corresponding right-side and left-side side wires to form the corresponding sides;

a belt structure superimposed in an external radius position with respect to the frame structure;

tread bracelet radially superimposed on the belt structure;

at least one layer of gray crosslinked elastomeric material applied in a radially internal position relative to the tread band;

a pair of sidewalls superimposed laterally on opposite sides with respect to the frame structure;

wherein at least one layer of gray crosslinked elastomeric material has the following characteristics:

dynamic modulus (E ′) of elasticity, measured at 70 ° C, not lower than 20 MPa, preferably from 25 MPa to 50 MPa;

the ratio between the tensile modulus at 100% elongation (M100) and the tensile modulus at 10% elongation (M10) is not lower than 1.5, preferably from 2 to 5.

The dynamic modulus (E ′) of elasticity can be measured using the Instron dynamic fixture in traction-compression mode, while the tensile modulus can be measured in accordance with ISO Standard 37: 1994. Further details related to the above measurement methods will be given in the examples below.

According to one preferred embodiment, said at least one layer of gray crosslinked elastomeric material has a dynamic elastic modulus (E ′), measured at 23 ° C., not lower than 30 MPa, preferably from 35 MPa to 70 MPa.

According to a further preferred embodiment, said at least one layer of gray crosslinked elastomeric material has a percentage fluctuation in tensile modulus at 10% elongation (M10) measured in a direction substantially parallel to the equatorial plane of the tire, with respect to to tensile modulus at 10% elongation (M10), measured in a direction substantially perpendicular to the equatorial plane of the tire, not higher than 20%, preferably not higher than 15%, more preferred but not higher than 5%.

The above vibration is an indicator of the isotropic behavior of the material forming the layer, since the direction parallel to the equatorial plane of the tire essentially corresponds to the direction in which the unvulcanized material leaves the extrusion unit (or optional calendering unit) to form a layer.

According to one preferred embodiment, said at least one layer of gray crosslinked elastomeric material has a thickness of less than 2 mm, preferably from 0.5 mm to 1.5 mm.

According to one preferred embodiment, said at least one layer of gray crosslinked elastomeric material is positioned between said tread band and said belt structure.

According to a further preferred embodiment, said at least one layer of gray crosslinked elastomeric material is disposed between said belt structure and said frame structure.

According to one preferred embodiment, said at least one layer of gray crosslinked elastomeric material is formed by a plurality of turns of a continuous elongated element.

Preferably, the tread band is formed by a plurality of turns of a continuous elongated element, said elongated element consisting of a crosslinkable elastomeric material. The specified elongated element can be obtained, for example, by extrusion of the specified stitched elastomeric material. Preferably, an unvulcanized tire is obtained by assembling its structural members on a toroidal support. Further details of the methods for forming and / or placing various tire components on a toroidal support are described, for example, in international publication WO 01/36185 and in European patent EP 976536.

The above combination of mechanical properties can be advantageously obtained by adding at least one layered inorganic material to the elastomeric material. Adding said layered inorganic material provides the above combination of mechanical properties without causing undesirable effects on other properties of the elastomeric material (i.e. viscosity, dispersion, cohesive tack, hysteresis).

Therefore, in accordance with one preferred embodiment, said elastomeric material includes:

(a) at least one diene elastomeric polymer;

(b) at least one layered inorganic material having a single layer thickness of from 0.1 nm to 30 nm, preferably from 0.05 nm to 15 nm, more preferably from 0.1 nm to 2 nm.

According to one preferred embodiment, said elastomeric material further includes (c) at least one reinforcing carbon black filler.

In accordance with one preferred embodiment, said elastomeric material further includes at least one silane coupling agent (d).

In accordance with one preferred variant embodiment, the specified layered inorganic material (b) is present in the elastomeric material in an amount of from 1 wt.h. up to 120 parts by weight, preferably from 5 parts by weight up to 80 parts by weight

For the purposes of the present description and the further claims, the term "parts by weight" refers to the mass parts of a given component of an elastomeric material per 100 mass parts of a diene elastomeric polymer.

According to one preferred embodiment, the layered inorganic material (b) that can be used in the present invention can be selected, for example, from phyllosilicates such as smectites, for example, montmorillonite, nontronite, beidellite, volkonskoite, hectorite, saponite, saukonite; vermiculitis; galloisitis; sericite or mixtures thereof. Montmorillonite is particularly preferred.

In order to make layered inorganic material (b) more compatible with the diene elastomeric polymer (a), said layered inorganic material (b) can be treated with a combining agent.

According to one preferred embodiment of the invention, said combining agent can be selected, for example, from quaternary ammonium or phosphonium salts having the general formula (I):

wherein:

- Y represents N or P;

- R ₁ , R ₂ , R ₃ and R ₄ , which may be the same or different, represent a linear or branched C ₁ -C ₂₀ alkyl or hydroxyalkyl group; a linear or branched C ₁ -C ₂₀ alkenyl or hydroxyalkenyl group; a group —R ₅ —SH or —R ₅ —NH, in which R ₅ represents a linear or branched C ₁ -C ₂₀ alkylene group; A C ₅ -C ₁₈ aryl group; A C ₇ -C ₂₀ arylalkyl or alkylaryl group; C ₅ -C ₁₈ cycloalkyl group, said cycloalkyl group possibly containing hetero atom such as oxygen, nitrogen or sulfur;

- X ^n- represents an anion, such as a chlorine ion, sulfate ion or phosphate ion;

- n is 1, 2 or 3.

The treatment of the layered inorganic material (b) with a combining agent can be carried out in accordance with known methods, such as, for example, the interaction of ion exchange between a layered inorganic material and a combining agent, which are described in more detail, for example, in US patents Nos. 4,136,103, 5747560 or 5952093 .

An example of the layered inorganic material (b), which can be used in accordance with the present invention and which is commercially available is the product known under the name of Dellite ^® 67G, from Laviosa Chimica Mineraria SpA

In accordance with one preferred embodiment, the diene elastomeric polymer (a) that can be used in the present invention can be selected from polymers commonly used in sulfur crosslinkable elastomeric materials that are particularly suitable for making tires, i.e. from elastomeric polymers or copolymers with an unsaturated chain having a glass transition temperature (T _g) generally below 20 ° C, preferably in the range from 0 ° C to -110 ° C. These polymers or copolymers may be of natural origin or may be prepared by solution polymerization, emulsion polymerization or gas phase polymerization of one or more conjugated diolefins, optionally mixed with at least one comonomer selected from monovinylarenes and / or polar comonomers in an amount of not more than 60 wt.%.

Conjugated diolefins usually contain from 4 to 12, preferably from 4 to 8, carbon atoms and can be selected, for example, from the group consisting of: 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 or mixtures thereof. 1,3-butadiene and isoprene are particularly preferred.

Monovinylarenes, which can optionally be used as comonomers, usually contain from 8 to 20, preferably from 8 to 12 carbon atoms, and can be selected, for example, from: styrene; 1-vinylnaphthalene; 2-vinylnaphthalene; various alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl derivatives of styrene, such as, for example, alpha-methyl styrene, 3-methyl styrene, 4-propyl styrene, 4-cyclohexyl styrene, 4-dodecyl styrene, 2-ethyl-4-benzyl styrene, 4-p- tolyl styrene, 4- (4-phenylbutyl) styrene or mixtures thereof. Styrene is especially preferred.

Polar comonomers that can optionally be used can be selected, for example, from: vinyl pyridine, vinyl quinoline, esters of acrylic acid and alkyl acrylic acid, nitriles or mixtures thereof, such as, for example, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, acrylonitrile or mixtures thereof .

Preferably, the diene elastomeric polymer (a) that can be used in the present invention can be selected, for example, from: cis-1,4-polyisoprene (natural or synthetic, preferably natural rubber), 3,4-polyisoprene, polybutadiene (in features of polybutadiene with a high content of 1,4-cis units), optionally halogen-containing copolymers of isoprene and isobutene, copolymers of 1,3-butadiene and acrylonitrile, copolymers of styrene and 1,3-butadiene, copolymers of styrene, isoprene and 1,3-butadiene, copolymers styrene 1,3-butadiene hen and acrylonitrile or mixtures thereof.

According to one preferred embodiment, said elastomeric material comprises at least 10 wt.%, Preferably from 20 wt.% To 100 wt.%, Based on the total weight of at least one diene elastomeric polymer (a) of natural rubber .

The above elastomeric material may optionally include at least one elastomeric polymer of one or more monoolefins with an olefin comonomer or derivatives thereof (a ′). Monoolefins can be selected from: ethylene and alpha-olefins, usually containing from 3 to 12 carbon atoms such as, for example, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, or mixtures thereof. Preferred are the following: copolymers between ethylene and an alpha olefin, optionally with a diene; isobutene homopolymers or copolymers thereof with small amounts of diene, which are optionally at least partially halogenated. The diene, optionally present, usually contains 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, vinyl norbornene or mixtures thereof. Among them, the following are particularly preferred: ethylene-propylene copolymers (EPR) or ethylene-propylene-diene copolymers (EPDM); polyisobutene; butyl rubbers; halobutyl rubbers, in particular chlorobutyl or bromobutyl rubbers or mixtures thereof.

You can also use a diene elastomeric polymer (a) or an elastomeric polymer (a ′) functionalized by reaction with suitable chain terminating agents or binding agents. In particular, diene elastomeric polymers obtained by anionic polymerization in the presence of an organometallic catalyst (especially an organolithium catalyst) can be functionalized by reacting residual organometallic groups derived from the catalyst with suitable chain terminating agents or binding agents such as, for example, imines, carbodiimines, alkylthalides substituted benzophenones, alkoxysilanes or aryloxysilanes (see, for example, European patent EP 451604 or US patent No. 4742124 or 4550142).

As disclosed above, said elastomeric material further includes at least one reinforcing carbon black filler (s).

According to one preferred embodiment, the carbon black reinforcing filler (s) that can be used in the present invention can be selected from those having a surface area of not less than 20 m ² / g (determined by the adsorption of CTAB, as described in ISO 6810: 1995).

In accordance with one preferred embodiment, said reinforcing carbon black filler (c) is present in the elastomeric material in an amount of from 0.1 parts by weight. up to 120 parts by weight, preferably from 20 parts by weight up to 90 parts by weight

As disclosed above, said elastomeric material further includes at least one silane coupling agent (d).

According to one preferred embodiment, the silane coupling agent (d) that can be used in the present invention can be selected from those which have at least one hydrolyzable silane group that can be identified, for example, by the following general formula (II) :

(R) ₃ Si-C _n H _2n -X (II)

in which the R groups, which may be the same or different, are selected from: alkyl, alkoxy or aryloxy groups or from halogen atoms, provided that at least one of the R groups is an alkoxy or aryloxy group; n is an integer from 1 to 6 inclusive; X is a group selected from: nitroso, mercapto, amino, epoxide, vinyl, imide, chloro, - (S) _m C _n H _2n -Si- (R) ₃ , or -S-COR, in which the type are integers from 1 to 6 inclusive and the R groups are defined as described above.

Among the silane coupling agents, those which are particularly preferred are bis (3-triethoxysilyl-propyl) tetrasulfide or bis (3-triethoxysilyl-propyl) disulfide. These binding agents can be used as such or as a suitable mixture with an inert filler (e.g. carbon black) so as to facilitate their incorporation into the elastomeric material.

In accordance with one preferred embodiment, said silane coupling agent (d) is present in the amount of 0.01 parts by weight of the elastomeric material. up to 10 parts by weight, preferably from 0.5 parts by weight up to 5 parts by weight

At least one additional reinforcing filler can advantageously be added to the above elastomeric material in an amount of usually from 0.1 parts by weight. up to 120 parts by weight, preferably from 20 parts by weight up to 90 parts by weight The reinforcing filler can be selected from fillers commonly used for crosslinked industrial products, in particular for tires, such as, for example, silicic acid filler, alumina, aluminosilicates, calcium carbonate, kaolin or mixtures thereof.

The silica filler that can be used in the present invention can usually be pyrogenic silica filler or preferably precipitated silica filler with a BET surface area (measured in accordance with ISO 5794/1) of 50 m ² / g to 500 m ² / g, preferably from 70 m ² / g to 200 m ² / g.

When a reinforcing filler comprising a silica filler is present, the elastomeric material can advantageously be mixed with a silane coupling agent (d) capable of reacting with the silica filler and combining it with a diene elastomeric polymer during vulcanization. Examples of silane coupling agents (d) that can be used are already disclosed above.

According to one preferred embodiment, the tire tread band is formed of a gray crosslinked elastomeric material having a dynamic elastic modulus (E ′) measured at 23 ° C. from 5 MPa to 25 MPa, preferably from 7 MPa to 20 MPa.

Preferably, said gray crosslinked elastomeric material has a dynamic modulus (E ′) of elasticity, measured at 100 ° C., from 3 MPa to 10 MPa, more preferably from 3.5 MPa to 8 MPa.

Preferably, said sulfur crosslinked elastomeric material has a delta tangent measured at 23 ° C. of from 0.20 to 0.90, more preferably from 0.30 to 0.70.

Preferably, said sulfur crosslinked elastomeric material has a delta tangent measured at 100 ° C. of from 0.10 to 0.35, more preferably from 0.15 to 0.30.

Preferably, said gray crosslinked elastomeric material has an international scale of hardness of rubber, measured at 23 ° C., from 65 to 85, more preferably from 70 to 80.

Preferably, said gray crosslinked elastomeric material has an international scale of hardness of rubber, measured at 100 ° C., from 45 to 75, more preferably from 55 to 66.

The specified dynamic modulus (E ′) of elasticity and the specified tangent delta can be measured using Instron dynamic device in the force-traction-compression mode, while the degree of hardness of rubber on the international scale can be measured in accordance with ISO 48: 1994 oppure 48: 1994 / Amd 1: 1999.

Additional details regarding the above measurement methods will be disclosed in the examples below.

Preferably, the gray crosslinked elastomeric material of the tread band includes at least one diene elastomeric polymer and at least one reinforcing filler selected from fillers commonly used in sulfur crosslinkable elastomeric materials that are particularly suitable for making tires, such as, for example, for those disclosed above with respect to at least a single layer gray crosslinked elastomeric material.

The elastomeric materials described above, both for a single-layer sulfur-crosslinked elastomeric material and for a tread band, can be vulcanized in accordance with known technologies, in particular sulfur-based vulcanizing systems commonly used for diene elastomeric polymers. To this end, in materials after one or more stages of thermomechanical processing, a sulfur-based vulcanizing agent is mixed together with vulcanization accelerators. In the last processing step, the temperature is usually kept below 120 ° C and preferably below 100 ° C so as to avoid any undesirable phenomenon of premature crosslinking.

The vulcanizing agent most advantageously used is sulfur or molecules containing sulfur (sulfur donors), with accelerators and activators known to those skilled in the art.

Activators that are particularly effective are zinc compounds and in particular ZnO, ZnCO _3, zinc salts of saturated or unsaturated fatty acids containing from 8 to 18 carbon atoms such as, for example, zinc stearate, which are preferably formed in situ in the elastomeric material from ZnO and a fatty acid, as well as BiO, PbO, Pb ₃ O ₄ , PbO _2, or a mixture thereof.

Accelerators that are commonly used can be selected from: dithiocarbamates, guanidine, thiourea, thiazoles, sulfenamides, thiurams, amines, xanthates, or mixtures thereof.

Said elastomeric materials may include other commonly used additives selected based on the particular application for which the composition is intended. For example, the following can be added to these materials: antioxidants, antioxidants, plasticizers, adhesives, antiozonants, modifying resins, fibers (for example, Kevlar® sludge) or mixtures thereof.

In particular, for the purpose of further improving manufacturability, a plasticizer, usually selected from mineral oils, vegetable oils, synthetic oils, or mixtures thereof, such as, for example, aromatic oil, naphthenic oil, phthalates, soybean oil, or mixtures thereof, can be added to said elastomeric to the material. The amount of plasticizer usually ranges from 0 parts by weight. up to 70 parts by weight, preferably from 5 parts by weight up to 30 parts by weight

The above elastomeric materials can be obtained by mixing together the elastomeric components with reinforcing filler and with other additives, optionally present, in accordance with the technologies known in the art. Mixing can be carried out, for example, using an open mixer such as an open crusher or a closed mixer with tangential rotors (Banbury) or with interlocking rotors (Intermix) or in continuous mixers such as Ko-Kneader (Buss) or twin-screw type with one screw rotation or opposite sides.

Next, the present invention will be described in more detail with examples of variants of its embodiments with reference to the accompanying Fig.1-2, which are views in cross section of part of the tire obtained in accordance with the present invention.

“A” indicates the axial direction and “r” indicates the radial direction. For simplicity, only a portion of the tire is shown in FIG. 1, with the remaining portion not shown being identical and located symmetrically with respect to the radial direction “r”.

The tire 100 includes at least one wire-frame layer 101, the opposite transverse edges of which are connected with the corresponding bead wires 102. The connection between the wire-layer layer 101 and the bead wires 102 is achieved here by wrapping the opposite transverse edges of the wire-frame layer 101 around the bead wires 102 so to form the so-called frame lapel 101a, as shown in Fig.1.

Alternatively, conventional bead wires 102 can be replaced with a pair of rounded rigid ring inserts formed of elongated components located on concentric spirals (not shown in FIG. 1) (see, for example, European patent applications EP 928680 and EP 928702). In this case, the carcass ply 101 is not wrapped around said annular inserts, and duplication is provided by a second carcass ply (not shown in FIG. 1) superimposed externally above the first.

The carcass ply 101 typically consists of a plurality of reinforcing cords arranged parallel to each other and at least partially covered by a layer of elastomeric compound. These reinforcing cords are usually made of textile fibers, for example viscose fiber, nylon or polyethylene terephthalate, or steel wires arranged together coated with a metal alloy (for example, copper / zinc, zinc / manganese, zinc / molybdenum / cobalt alloys, etc.) .

The skeleton layer 101 is typically a radial type layer, i.e. it includes reinforcing cords located essentially in a perpendicular direction with respect to the annular direction. Each bead wire 102 is placed on a bead 103 formed along the inner circumferential edge of the tire 100 with which the tire comes into contact on the brace (not shown in FIG. 1) forming part of the vehicle wheel. The space formed by each frame lapel 101a comprises an onboard filler cord 104, in which the onboard wires 102 are internal. Anti-abrasive tape 105 is usually placed in an axial internal position with respect to the frame flap 101a.

The belt structure 106 is laid along the circumference of the carcass ply 101. In the particular embodiment of FIG. 1, the belt structure 106 includes two belt bands 106a, 106b that include a plurality of reinforcing cords, typically metal cords, that are parallel to each other on each tape and intersecting with respect to the adjacent tape, oriented so as to form a given angle with respect to the annular direction. At least one zero reinforcing layer 106 c, commonly known as a “0 ° breaker,” which typically includes a plurality of reinforcing cords, typically textile cords, angled, may optionally be applied to the radially farthest off-center belt 106b several degrees with respect to the annular direction and coated and welded together by means of an elastomeric material.

The sidewall 108 is also superimposed externally on the carcass ply 101, which sidewall extends axially outward from the bead 103 toward the end of the belt structure 106.

The tread band 109, the transverse edges of which are connected to the sidewalls 108, are laid around the circumference in a position outside radially to the belt structure 106. Outside, the tread band 109 has a bending surface 109a intended to come into contact with the ground. Annular grooves that are connected by transverse recesses (not shown in FIG. 1) so as to characterize a plurality of nodes of various shapes and sizes distributed on the curving surface 109a are usually made on this surface 109a, which is shown for simplicity in FIG. 1 as smooth.

A layer of gray crosslinked elastomeric material 111 in accordance with the present invention is located between the belt structure 106 and the tread band 109.

As shown in FIG. 1, a layer of gray crosslinked elastomeric material 111 may have the same thickness.

Alternatively, the thickness of the layer of gray crosslinked elastomeric material 111 may have a different thickness in the transverse direction. For example, it may be larger near its outer edges than in the central zone.

1, a layer of gray crosslinked elastomeric material 111 extends above a surface substantially corresponding to a development surface of said belt structure 106. Alternatively, said layer of gray crosslinked elastomeric material 111 extends only along at least one development portion of said belt structure 106 for example, on opposite side portions of said belt structure 106 (not shown in FIG. 1).

A tape made of elastomeric material 110, commonly known as a “mini-sidewall", may optionally be present in the connecting zone between the sidewalls 108 and the tread band 109, which mini-sidewall is usually obtained by co-extrusion with the tread band and it provides an improvement in the mechanical interaction between the tread band 109 and sidewalls 108. Alternatively, the end portion of sidewall 108 directly covers the transverse edge of the tread band 109.

In the case of tubeless tires, the rubber layer 112, commonly known as the "sealing layer", which provides the necessary tightness for the air pressure in the tire, can also be made in a radial internal position with respect to the carcass layer 101.

Figure 2 shows the same tire 100 as in Figure 1, with the only difference being that the layer of gray crosslinked elastomeric material 111 in accordance with the present invention is located between the belt structure 106 and the carcass ply 101.

The method of obtaining a tire in accordance with the present invention can be carried out in accordance with technologies and the use of devices that are known in the prior art, as described, for example, in patents EP 199064, US 4872822, US 4768937, and this method includes at least one stage of the production of unvulcanized tires and at least one stage of vulcanization of the tire.

More specifically, the method for producing a tire includes the steps of obtaining, in advance and separately from each other, a series of semi-finished products corresponding to various structural elements of the tire (tread layers, belt structure, side wires, filler cords, sidewalls and tread band), which are then joined together using a suitable industrial installation. Further, the sequential vulcanization step combines all of the above-mentioned semi-finished products together with the production of a monolithic block, i.e. finished tire.

The stage of obtaining the said semi-finished products will be preceded by the stage of obtaining and molding various mixtures from which these semi-finished products are made, in accordance with generally accepted technologies.

The unvulcanized tire thus obtained then proceeds to the subsequent stages of molding and vulcanization. For this purpose, a vulcanization mold is used, which is adapted to accommodate the tire obtained inside the cavity of the mold having walls that are oppositely formed to form the outer surface of the tire after vulcanization is completed.

Alternative methods for manufacturing a tire or tire parts without the use of semi-finished products are disclosed, for example, in the aforementioned patent applications EP 928680 and EP 928702.

An unvulcanized tire can be molded by injecting fluid under pressure into the space formed by the inner surface of the tire so as to press the outer surface of the unvulcanized tire against the walls of the forming cavity. In one of the molding methods, widely used, a vulcanization chamber made of an elastomeric material, filled with steam and / or other fluid under pressure, is filled with air inside the tire that covers the inside of the molding cavity. In this regard, the unvulcanized tire is compressed with respect to the outer walls of the molding cavity, thereby obtaining the desired molding. Alternatively, molding can be carried out without an inflating vulcanization chamber, providing the outside of the tire with a toroidal metal support made in accordance with the configuration of the outer surface of the obtained tire, as described, for example, in EP 242840. A difference in the thermal expansion coefficient is used between the toroidal metal support and the crude elastomeric material to achieve the appropriate molding pressure.

From this point of view, the vulcanization stage of the crude elastomeric material present in the tire is carried out. To this end, the outer wall of the vulcanization mold is placed in contact with a heating fluid (usually steam) so that the outer wall reaches a maximum temperature typically from 100 ° C to 230 ° C. At the same time, the inner surface of the tire is heated to the vulcanization temperature using the same fluid under pressure used to press the tire against the outer walls of the molding cavity, heated to a maximum temperature of 100 ° C to 250 ° C. The time required to obtain a satisfactory degree of vulcanization over the entire mass of the elastomeric material can vary between 3 minutes and 90 minutes in general and depends mainly on the size of the tire. When vulcanization is completed, the tire is removed from the vulcanization mold.

Now the present invention will be illustrated by means of a number of production examples, which are explanatory and do not introduce any limitation in the scope of this invention.

EXAMPLES 1-2

Obtaining elastomeric materials

The elastomeric materials shown in Table 1 were obtained as follows (amounts of various components are given in parts by weight).

All components except sulfur, accelerator (DCBS), and HMT were mixed together in a closed rubber mixer (model Pomini PL 1.6) for about 5 minutes ( ^1st stage). As soon as the temperature reached 145 ± 5 ° C, the elastomeric material was discharged. Was added sulfur, the accelerator and HMT, and mixing was carried out on an open roll mixer (2 ^aya step).

TABLE 1 EXAMPLE one (*) 2 ^1st stage Nr 80 twenty E-sbr - 80 N326 fifty fifty Zinc oxide four four Stearic acid 2 2 Resorcinol 1.3 1.3 Antioxidant 1,5 1,5 Si69 ^® - four Kevlar ^® 26 - Dellite ^® 67G - 40 ^2nd stage DCBS 1.3 1.3 PVI 0.2 0.2 Sulfur 3.0 3.0 Hmmm four four (*): comparative

NR: natural rubber;

E-SBR 1712: butadiene-styrene copolymer prepared in emulsion (Europrene ^® 1712 - Polimeri Europa);

N326: soot;

Antioxidant: phenyl-p-phenylenediamine;

Si69: bis (triethoxysilylpropyl) tetrasulfide (Degussa-Huls);

Kevlar ^® Engineered Elastomer: a mixture of 23 wt.%. Kevlar® and 77 wt.% Natural rubber (DuPont);

Dellite ^® 67G: organo-modified montmorillonite belonging to the smectite series (Laviosa Chimica Mineraria S.p.A.);

DCBS (accelerator): benzothiazyl-2-dicyclohexyl sulfenamide (Vulcacit ^® DZ / EGC - Bayer);

PVI (inhibitor): N-cyclohexylthiophthalimide (Santogard® PVI - Monsanto);

HMMM: hexamethoxymethylmelamine

Mooney viscosity ML (1 + 4) at 100 ° C was measured in accordance with ISO 289-1: 1994 on uncrosslinked elastomeric materials obtained as described above. The results are shown in Table 2.

Static mechanical properties in accordance with ISO 37: 1994 were measured at different elongations (10%, 50% and 100%) both in the calendaring direction and in the direction perpendicular to the samples of the above-mentioned elastomeric materials vulcanized at 170 ° C in within 10 minutes The results are shown in Table 2.

Table 2 also shows the dynamic mechanical properties measured using the Instron dynamic fixture using the pull-compression technique in accordance with the following methods. A test sample for a crosslinked gray material having a cylindrical shape (length = 25 mm; diameter = 12 mm), which was compressed by preloading up to 10% longitudinal deformation with respect to the initial length and kept at a pre-fixed temperature (23 ° C or 70 ° C) during the entire duration of the test, was subjected to dynamic sinusoidal tension having an amplitude of ± 2.2% with respect to the length before loading with a frequency of 100 Hz. Dynamic mechanical properties are expressed in units of values of the dynamic modulus (E ′) of elasticity and tangent delta (loss factor). As is known, the tangent delta value is calculated as the ratio between the viscosity modulus (E ′ ′) and the elastic modulus (E ′), both of which are determined by the above dynamic measurements.

TABLE 2 EXAMPLE one (*) 2 Mooney Viscosity ML (1 + 4) 44.0 36.0 STATIC MECHANICAL PROPERTIES CALENDAR DIRECTION Modulus 10% (MPa) 11.32 4.20 50% modulus (MPa) 11.56 8.35 Modulus 100% (MPa) 11.29 13.48 M100 / M10 ⁽¹⁾ 1,0 3.2 Breaking stress (MPa) 11.46 14.12 DIRECTION PERPENDICULAR CALENDARING Modulus 10% (MPa) 6.38 4.02 50% modulus (MPa) 8.33 7.92 Modulus 100% (MPa) 9.15 12.98 M100 / M10 ⁽¹⁾ 1.43 3.23 Breaking stress (MPa) 12.61 13.52 DYNAMIC MECHANICAL PROPERTIES E ′ (23 ° C) (MPa) 34.30 56.62 E ′ (70 ° C) (MPa) 26,50 35.40 Tangent delta (23 ° C) 0.353 0.385 Tangent delta (70 ° C) 0.264 0.298

(*): comparative

⁽¹⁾ : ratio between tensile modulus at 100% tension (M100) and tensile modulus at 10% tension (M10).

The results shown in Table 2 show that a crosslinked industrial product made from an elastomeric material, as disclosed in the present invention (Example 2), has improved mechanical properties, both static and dynamic, in particular with respect to the modulus of elasticity tensile, tensile stress and dynamic elastic modulus. In addition, the elastomeric material in accordance with the present invention shows both longitudinal and transverse reinforcement, and an increase in tensile modulus with increasing applied elongation. These results are obtained without negative impact on the hysteresis properties. In addition, the results given in Table 2 also show that the viscosity value of said elastomeric material did not increase.

Example 3-4

Tires were obtained in accordance with Figure 1, containing a layer of gray crosslinked elastomeric material in accordance with Example 1 (Example 3 - comparative) and in accordance with Example 2 (Example 4 - in accordance with the present invention).

The elastomeric material of the tread band shown in Table 3 was obtained as disclosed in Example 1-2 (the amounts of the various components are given in parts by weight, unless otherwise indicated).

TABLE 3 EXAMPLE four ^1st stage BR 25 E-SBR 1721 75 Silica 35 N234 35 Zinc oxide 3 Stearic acid 2 Antioxidant 2 Microcrystalline paraffin one Si69 _® 1.75 Aromatic oil fifteen ^2nd stage Cbs 1.8 DPG 1.9 Sulfur 1.4

BR: polybutadiene with a high content of cis-1.3 units (Europrene ^® Neocis BR40 - Polimeri Europa);

E-SBR 1721: butadiene-styrene copolymer prepared in emulsion (Europrene ^® 1721 - Polimeri Europa);

Silica: precipitated silica filler with a BET surface area of about 165 m ² / g

N234: carbon black;

Antioxidant: phenyl-p-phenylenediamine;

Si69: bis (triethoxysilylpropyl) tetrasulfide (Degussa-Huls);

CBS (accelerator): N-cyclohexyl-2-benzothiazylsulfenamide (Vulcacit ^® CZ - Bayer);

DPG: diphenylguanidine (product of Vulcacit ^® D - Bayer).

Static mechanical properties were measured as presented in Examples 1-2. The results are shown in Table 4. The dynamic mechanical properties were measured using an Instron dynamic fixture using the pull-compression technique in accordance with the following methods. A test sample for a crosslinked gray material having a cylindrical shape (length = 25 mm; diameter = 14 mm), which was compressed by preloading up to 25% of longitudinal deformation with respect to the initial length and kept at a pre-fixed temperature (23 ° C or 70 ° C) during the entire duration of the test, was subjected to dynamic sinusoidal tension with an amplitude of ± 3.33% with respect to the length before loading with a frequency of 100 Hz. Dynamic mechanical properties are expressed in units of values of the dynamic modulus (E ′) of elasticity and tangent delta (loss factor). As is known, the tangent delta value is calculated as the ratio between the viscosity modulus (E ′) and the elastic modulus (E ′), both of which are determined by the above dynamic measurements. The results are shown in Table 4. The degree of hardness of the rubber was measured at 23 ° C and at 100 ° C in accordance with ISO 48 on samples of the above-mentioned elastomeric materials vulcanized at 170 ° C for 10 min. The results obtained are given in Table 4.

TABLE 4 EXAMPLE four STATIC MECHANICAL PROPERTIES Modulus 100% (MPa) 2,5 Modulus 300% (MPa) 11.0 Breaking stress (MPa) 17.3 Elongation at break (%) 474 Hardness (23 ° C) 75.0 Hardness (100 ° C) 63.0 DYNAMIC MECHANICAL PROPERTIES E ′ (23 ° C) (MPa) 11.56 E ′ (100 ° C) (MPa) 6.02 Tangent delta (23 ° C) 0.439 Tangent delta (100 ° C) 0.194

Tires of size 285 / 40R19 were installed on a Ferrari F137 and tested on the race track. The results are shown in Table 5.

In order to evaluate the behavior of the tire, the test driver simulated some characteristic maneuvers (for example, changing the route, entering the corner, leaving the corner), carried out at a constant speed, during acceleration and during braking. Then, the test driver evaluated the behavior of the tire and set a point score depending on the characteristics of the tire during the specified maneuver.

Management is usually divided into two varieties (soft control and tight control) depending on the type of maneuver conducted by the test driver. Soft steering refers to the use of the tire under normal driving conditions, i.e. under conditions of normal speed and good lateral grip. Tests with tight control, on the contrary, describe the behavior of the tire with limited adhesion, i.e. under extreme driving conditions. In the latter case, the test driver performs maneuvers that an ordinary driver can be forced to carry out in case of unforeseen and dangerous circumstances: sharp control at high speed, a sudden change in the route for avoiding obstacles, sudden braking and the like.

Two different types of tests were performed: behavior at normal speed (soft control) and behavior with limited adhesion (tight control).

Since the tests of soft control were affected, the test driver evaluated: the emptiness in the center, that is, the delay and the degree of response of the car at small control angles; control response speed when entering a turn; enhanced control response when cornering; centering in a bend, i.e. the tire’s ability to hold a car in a bend with a constant radius without continuous control adjustments; retunement, that is, the tire’s ability to allow the car to return to a straight path at the exit of a turn with limited and weakened lateral vibrations.

Since the tests of tight control were affected, the test driver evaluated: the force on the steered wheel during a sharp turn; the reaction speed when turned on, that is, the behavior of the tire when switching to entering a turn that is passable at a limited speed; balancing, i.e. the degree of oversteer or understeer; compliance, that is, the ability of the tire to absorb strong, rapid movement of the load due to a sudden change in track without excessive deformation and therefore without jeopardizing the stability and controllability of the vehicle; cornering failure, that is, the ability of the tire to attenuate the effects of instability arising from a sudden failure of the gas pedal during a corner that passes through at a speed limit; controllability, that is, the ability of the tire to maintain and / or return the vehicle to the trajectory after loss of traction.

Table 5 summarizes the list of test driver ratings for tire controllability. The results of these tests are expressed through a scale of values representing the subjective opinion expressed by the test driver through a system of points. The values reproduced in the following table represent the average value between the values obtained in several test series (for example, 5-6 tests) and the data of several test drivers. It should be noted that the scale of the values reaches from a minimum of 4 to a maximum of 9.

Table 5 3 (*) four Management behavior (soft control) Void in the center 7.0 7.0 Speed reaction 7.0 7.0 Gain 7.0 7.0 Cornering 7.0 7.5 Subsequent alignment 7.5 7.5 Restrictive behavior (tight control) Power on reaction rate 7.0 7.0 Balancing 6.5 7.0 Exit 6.5 7.0 Turn Failure 6.5 7.5 Understeer 7.0 7.0 Oversteer 6.5 7.5 Controllability 6.5 7.5 (*): comparative

The results shown in Table 5 clearly show that the tire in accordance with the present invention (Example 4) has better behavior with respect to the comparative tire (Example 3), in particular, shows improved performance when used at high speeds and / or extreme driving conditions (tight control), along with good behavior under normal driving conditions (soft driving), in particular, with increased comfort and maneuverability.

Claims (50)

1. A tire for vehicle wheels, including a frame structure formed essentially in a toroidal configuration, the opposite side edges of which are connected with the corresponding right-side and left-side side wires to form the corresponding sides; a belt structure superimposed in an external radius position with respect to the frame structure; tread bracelet radially superimposed on the belt structure; at least one layer of a gray crosslinked elastomeric material including at least one diene elastomeric polymer and at least one layered inorganic material having a single layer thickness of from 0.01 to 30 nm, which is superimposed in the inner in radius position relative to the tread band; a pair of sidewalls superimposed laterally on opposite sides with respect to the frame structure; wherein at least one layer of gray crosslinked elastomeric material has the following characteristics: dynamic modulus (E ′) of elasticity, measured at 70 ° C, not lower than 20 MPa; the ratio between the tensile modulus at 100% elongation (M100) and the tensile modulus at 10% elongation (M10), measured in the calendaring direction and in the direction perpendicular to calendaring, is not less than 1.5. 2. The tire according to claim 1, in which at least one layer of gray crosslinked elastomeric material has a dynamic modulus (E ′) of elasticity, measured at 70 ° C, from 25 to 50 MPa. 3. The tire according to claim 1 or 2, in which at least one layer of gray crosslinked elastomeric material has a relationship between tensile modulus at 100% elongation (M100) and tensile modulus at 10% elongation (M10) from 2 to 5. 4. The tire according to claim 1, in which at least one layer of gray crosslinked elastomeric material has a dynamic modulus (E ′) of elasticity, measured at 23 ° C, not lower than 30 MPa. 5. The tire according to claim 4, in which at least one layer of gray crosslinked elastomeric material has a dynamic modulus (E ′) of elasticity, measured at 23 ° C, from 35 to 70 MPa. 6. The tire according to claim 1, in which at least one layer of gray crosslinked elastomeric material has a percentage deviation of the tensile modulus at 10% elongation (M10), measured in a direction substantially parallel to the equatorial plane of the tire with respect to tensile modulus at 10% elongation (M10), measured in a direction substantially perpendicular to the equatorial plane of the tire, not more than 20%. 7. The tire according to claim 6, in which at least one layer of gray crosslinked elastomeric material has a percentage deviation of the tensile modulus at 10% elongation (M10), measured in a direction substantially parallel to the equatorial plane of the tire with respect to tensile modulus at 10% elongation (M10), measured in a direction substantially perpendicular to the equatorial plane of the tire, not more than 15%. 8. The tire according to claim 7, in which at least one layer of gray crosslinked elastomeric material has a percentage deviation of the tensile modulus at 10% elongation (M10) measured in a direction substantially parallel to the equatorial plane of the tire with respect to tensile modulus at 10% elongation (M10), measured in a direction substantially perpendicular to the equatorial plane of the tire, not more than 5%. 9. The tire according to claim 1, in which at least one layer of gray crosslinked elastomeric material has a thickness of less than 2 mm 10. The tire according to claim 9, in which at least one layer of gray crosslinked elastomeric material has a thickness of from 0.5 to 1.5 mm 11. The tire according to claim 1, in which at least one layer of gray crosslinked elastomeric material is placed between the tread band and the belt structure. 12. The tire according to claim 1, in which at least one layer of gray crosslinked elastomeric material is placed between the belt structure and the frame structure. 13. The tire according to claim 1, in which at least one layer of gray crosslinked elastomeric material is formed by many turns of a continuous elongated element. 14. The tire according to claim 1, in which the layered inorganic material (b) has a single layer thickness of from 0.05 to 15 nm. 15. The tire according to 14, in which the layered inorganic material (b) has a single layer thickness of from 0.1 to 2 nm. 16. The tire according to claim 1, in which the layered inorganic material (b) is present in the elastomeric material in an amount of from 1 to 120 parts by weight 17. The tire according to clause 16, in which the layered inorganic material (b) is present in the elastomeric material in an amount of from 5 to 80 parts by weight 18. The tire according to claim 1, in which the layered inorganic material (b) is selected from phyllosilicates, such as smectites, such as montmorillonite, nontronite, beidellite, volkonskoit, hectorite, saponite, saukonite, vermiculite, galloisite, sericite, or mixtures thereof. 19. The tire according to claim 18, wherein the layered inorganic material (b) is montmorillonite. 20. The tire according to claim 1, in which the layered inorganic material (b) is treated with a combining agent. 21. The tire according to claim 20, in which the combining agent is selected from Quaternary ammonium or phosphonium salts with the General formula (I):

where Y represents N or P; R ₁ , R ₂ , R ₃ and R ₄ , which may be the same or different, represent a linear or branched C ₁ -C ₂₀ alkyl or hydroxyalkyl group; a linear or branched C ₁ -C ₂₀ alkenyl or hydroxyalkenyl group; a group —R ₅ —SH or —R5 — NH, in which R ₅ represents a linear or branched C ₁ -C ₂₀ alkylene group; A C ₆ -C ₁₈ aryl group; A C ₇ -C ₂₀ arylalkyl or alkylaryl group; A C ₅ -C ₁₈ cycloalkyl group, said cycloalkyl group optionally containing a heteroatom such as oxygen, nitrogen or sulfur; X ^{n -} represents an anion such as a chlorine ion, sulfate ion or phosphate ion; n is 1, 2 or 3. 22. The tire according to claim 1, in which the diene elastomeric polymer (a) has a glass transition temperature below 20 ° C. 23. The tire according to item 22, in which the diene elastomeric polymer (a) is selected from the group consisting of natural or synthetic cis-1,4-polyisoprene, 3,4-polyisoprene, polybutadiene, optionally halogen-containing copolymers of isoprene and isobutene, copolymers 1 , 3-butadiene and acrylonitrile, copolymers of styrene and 1,3-butadiene, copolymers of styrene, isoprene and 1,3-butadiene, copolymers of styrene, 1,3-butadiene and acrylonitrile, or mixtures thereof. 24. The tire according to claim 1, in which the elastomeric material is at least 10 wt.% With respect to the total weight of at least one diene elastomeric polymer (a) natural rubber. 25. The tire according to paragraph 24, in which the elastomeric material is from 20 to 100 wt.% With respect to the total weight of at least one diene elastomeric polymer (a) natural rubber. 26. The tire according to claim 1, in which the elastomeric material includes at least one elastomeric polymer of one or more monoolefins with an olefin comonomer or its derivatives (a ′). 27. The tire of claim 26, wherein the elastomeric polymer (a ′) is selected from the group consisting of ethylene propylene copolymers (EPR) or ethylene propylene copolymer copolymers (EPDM), polyisobutene, butyl rubbers, halobutyl rubbers, or mixtures thereof . 28. The tire according to claim 1, in which the elastomeric material includes at least one carbon black filler (s). 29. The tire of claim 28, wherein the carbon black filler (c) has a surface area of not less than 20 m ² / g (determined by CTAB adsorption as described in ISO 6810: 1995). 30. The tire according to claim 28, wherein the carbon black filler (c) is present in the elastomeric material in an amount of from 0.1 to 120 parts by weight. 31. The tire according to claim 30, in which the carbon black filler (s) is present in the elastomeric material in an amount of from 20 to 90 parts by weight 32. The tire according to claim 1, in which the elastomeric material includes at least one silane coupling agent (d). 33. A tire according to claim 32, wherein the silane coupling agent (d) is selected from agents that have at least one hydrolyzable silane group, which can be identified by the following general formula (II): (R) ₃ Si — C _n H _2n —X (II), in which R groups, which may be the same or different, are selected from: alkyl, alkoxy or aryloxy groups or from halogen atoms, provided that at least one of the R groups is an alkoxy or aryloxy group; n is an integer from 1 to 6 inclusive; X is a group selected from: nitroso, mercapto, amino, epoxide, vinyl, imide, chloro, - (S) _m C _n H _2n -Si- (R) ₃ , or -S-COR, in which the type are integers from 1 to 6 inclusive, and R groups are defined as described above. 34. The tire according to p, in which the silane coupling agent (d) is present in the elastomeric material in an amount of from 0.01 to 10 parts by weight 35. The tire according to clause 34, in which the silane coupling agent (d) is present in the elastomeric material in an amount of from 0.5 to 5 parts by weight 36. The tire according to claim 1, in which at least one additional reinforcing filler is present in an amount of from 0.1 to 120 parts by weight in elastomeric material. 37. The tire according to clause 36, in which the reinforcing filler is a silicic acid filler. 38. The tire according to clause 36, in which there is at least one silane coupling agent (d). 39. The tire according to claim 1, in which the tread band is formed of a gray crosslinked elastomeric material having a dynamic modulus of elasticity, measured at 23 ° C, from 5 to 25 MPa. 40. The tire according to § 39, in which the tread band is formed of a gray crosslinked elastomeric material having a dynamic modulus of elasticity, measured at 23 ° C, from 7 to 20 MPa. 41. The tire according to claim 1, in which the tread band is formed of a gray crosslinked elastomeric material having a dynamic modulus of elasticity, measured at 100 ° C, from 3 to 10 MPa. 42. The tire according to paragraph 41, wherein the tread band is formed of a gray crosslinked elastomeric material having a dynamic modulus of elasticity measured at 100 ° C. of 3.5 to 8 MPa. 43. The tire according to claim 1, in which the tread band is formed from a gray crosslinked elastomeric material having a tangent delta, measured at 23 ° C, from 0.20 to 0.90. 44. The tire according to item 43, in which the tread band is formed of a gray crosslinked elastomeric material having a tangent delta, measured at 23 ° C, from 0.30 to 0.70. 45. The tire according to claim 1, in which the tread band is formed of a gray crosslinked elastomeric material having a tangent delta measured at 100 ° C. from 0.10 to 0.35. 46. The tire according to item 45, in which the tread band is formed of a gray crosslinked elastomeric material having a tangent delta, measured at 100 ° C, from 0.15 to 0.30. 47. The tire according to claim 1, in which the tread band is formed from a gray crosslinked elastomeric material having a degree of rubber hardness on an international scale, measured at 23 ° C., from 65 to 85. 48. The tire according to clause 47, in which the tread band is formed of gray crosslinked elastomeric material having an international hardness of rubber measured at 23 ° C. from 70 to 80. 49. The tire according to claim 1, in which the tread band is formed of a gray crosslinked elastomeric material having an international hardness of rubber measured at 100 ° C. from 45 to 75. 50. The tire according to § 49, in which the tread band is formed of gray crosslinked elastomeric material having an international scale of hardness of rubber, measured at 100 ° C, from 55 to 66.

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