TYRE FOR VEHICLE WHEELS

Abstract

The present invention relates to a tyre (100) for vehicle wheels comprising at least one carcass structure (101), a tread band (109) applied in a position radially external to said carcass structure, and a pair of sidewalls (108) applied laterally on the opposite sides with respect to said carcass structure, where on at least one sidewall of said pair of sidewalls (108), a label (120) is applied comprising a protective layer (121), an adhesive layer (123), and possibly one or more ink layers (122) interposed between said protective layer (121) and said adhesive layer (123), where said adhesive layer (123) adheres the label (120) to the surface of said sidewall, where said protective layer (121) comprises polyester-based and/or polyether-based cross-linked aliphatic polyurethanes exhibiting dynamic elastic modulus values E′, measured at 25° C., static tensile deformation 1%, dynamic deformation +0.1%, and frequency 1 Hz, equal to or higher than about 5 MPa, and a residual deformation measured at 25° C. after 4 cycles of deformation from 0% to 12%, equal to or lower than about 1%.

Claims

1. A tyre (100) for vehicle wheels comprising at least one carcass structure (101), a tread band (109) applied in a position radially external to said carcass structure, and a pair of sidewalls (108) applied laterally on the opposite sides with respect to said carcass structure, where a label (120) is applied on at least one sidewall of said pair of sidewalls (108), said label (120) comprising a protective layer (121), an adhesive layer (123), and possibly one or more ink layers (122) interposed between said protective layer (121) and said adhesive layer (123), where said adhesive layer (123) adheres the label (120) to the surface of said sidewall, where said protective layer (121) comprises polyester-based and/or polyether-based cross-linked aliphatic polyurethanes exhibiting dynamic elastic modulus values E′, measured at 25° C., static tensile deformation 1%, dynamic deformation ±0.1%, and frequency 1 Hz, equal to or higher than about 5 MPa, and a residual deformation measured at 25° C. after 4 cycles of deformation from 0% to 12%, equal to or lower than about 1%.

2. The tyre according to claim 1, characterised in that said polyester-based and/or polyether-based cross-linked aliphatic polyurethanes exhibit dynamic elastic modulus values equal to or lower than about 25 MPa, more preferably equal to or lower than about 20 MPa.

3. The tyre according to claim 1, characterised in that said polyester-based and/or polyether-based cross-linked aliphatic polyurethanes exhibit a residual deformation, measured at 25° C. after 4 cycles of deformation from 0% to 12%, equal to or lower than about 0.5%.

4. The tyre according to claim 1, characterised in that the thickness of said protective layer is in the range of from 20 to 300 μm, preferably from 50 to 200 μm, and even more preferably from 75 to 150 μm.

5. The tyre according to claim 1, characterised in that said protective layer is made of a transparent or coloured polyurethane film.

6. The tyre according to claim 5, characterised in that said coloured protective layer comprises an amount of pigment ranging from about 1% to 30% by weight, preferably from 3% to 20% by weight, with respect to the overall weight of the protective layer.

7. The tyre according to claim 1, characterised in that said protective layer comprises transparent or coloured polyurethane films.

8. The tyre according to claim 1, characterised in that said ink layer is printed on said protective layer by means of silk-screen, digital, flexographic, and/or pad printing.

9. The tyre according to claim 1, characterised in that the thickness of said ink layer is in the range of from 1 to 100 μm, preferably from 5 to 50 μm, and even more preferably from 5 to 20 μm

10. The tyre according to claim 1, characterised in that said ink layer comprises polyurethane-based inks.

11. The tyre according to claim 1, characterised in that said adhesive layer comprises pressure sensitive adhesives (PSA) and thermally activatable adhesives (TA).

12. The tyre according to claim 11, characterised in that said adhesive layer comprises adhesives based on natural or synthetic rubber, acrylic adhesives, vinyl ether adhesives, silicone adhesives, urethane-based adhesives, and mixtures of two or more thereof.

13. The tyre according to claim 11, characterised in that said adhesive layer comprises adhesives with an adhesion force, measured according to the ISO 11339 standard at a temperature of 23° C. between two PET films, equal to or greater than 2N, preferably equal to or greater at 4N, more preferably equal to or greater than 10N.

14. The tyre according to claim 11, characterised in that the thickness of said adhesive layer is in the range of from 5 to 400 μm, preferably from 20 to 200 μm, and even more preferably from 35 to 100 μm.

15. The tyre according to claim 1, characterised in that said pair of sidewalls is made with a non-staining cross-linkable elastomeric composition, comprising (i) at least one diene elastomeric polymer, and (ii) an ozone protection system.

16. The tyre according to claim 15, characterised in that said ozone protection system substantially consists of at least one phenolic antioxidant in an amount equal to or greater than 3 phr, preferably equal to or greater than 4 phr, optionally in combination with at least one cyclic acetal or enol-ether antioxidant, in an amount equal to or greater than 1 phr, preferably equal to or greater than 2 phr.

17. The tyre according to claim 15, characterised in that said phenolic antioxidant is selected from the group consisting of pentaerythrityl tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]; 2,2-thio-diethylene bis-[(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate)]; octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate; isooctyl-3-(3,5-di-t-butyl-4-hydroxy-phenyl)propionate; 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene; 4,6-bis(dodecylthiomethyl)-o-cresol; 4,6-bis(octytiomethyl)-o-cresol; triethyleneglycol-bis[(3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate)]; 1,6-hexanediol-bis[(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]; 4-{[4,6-bis(octylsulfanil)-1,3,5-triazin-2-yl]amino}-2,6-di-t-butylphenol.

18. The tyre according to claim 15, characterised in that said cyclic acetal or enol-ether antioxidant is selected from the group consisting of 3,9-di-3-cyclohexen-1-yl-2,4,6,10-tetraoxaspyro[5.5]undecane and cyclohexen-3-ylidenmethyl-benzylether.

Description

DRAWINGS

[0139] The description is given hereinafter with reference to the accompanying drawings, provided only for illustrative and, therefore, non-limiting purposes, in which:

[0140] FIG. 1 shows a cross half-section showing a tyre for motor vehicle wheels according to a first embodiment of the present invention,

[0141] FIG. 2 shows a cross-section of the label according to the present invention comprising a protective layer and an adhesive layer;

[0142] FIG. 3 shows a cross-section of the label according to the present invention comprising a protective layer, an ink layer and an adhesive layer.

DETAILED DESCRIPTION OF THE INVENTION

[0143] The present description relates by way of example to a tyre for motor vehicle wheels. The Applicant believes that the present invention can also be applied to tyres for different vehicles such as heavy vehicles, motorcycles, bicycles.

[0144] In FIG. 1, “a” indicates an axial direction and “r” indicates a radial direction. For simplicity, FIG. 1 shows only a portion of the tyre, the remaining portion not shown being identical and arranged symmetrically with respect to the radial direction “r”.

[0145] With reference to FIGS. 1, the tyre 100 for motor vehicle wheels 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 reinforcement annular structure 103, the so-called bead, intended for anchoring the tyre onto a corresponding mounting rim, not shown.

[0146] The carcass structure is usually of radial type, i.e. the mutually parallel reinforcement 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 tire.

[0147] Alternatively, tires (not shown) are provided with cross-ply carcass structures.

[0148] In such tyres, the carcass structure may comprise at least a first and a second radially overlapping carcass ply, each made of elastomeric material and comprising a plurality of mutually reinforcing elements arranged parallel to one another.

[0149] The carcass plies are radially overlapped so that the reinforcing elements of a ply are inclined with respect to the reinforcing elements of the radially overlapped carcass ply and to the equatorial plane.

[0150] Said reinforcing elements may consist of metallic and/or textile cords, for example steel in the case of metallic cords or lyocell, rayon, nylon, polyester [for example polyethylene naphthalate (PEN)] in the case of textile cords. Each reinforcement annular 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 FIG. 1.

[0151] In one embodiment, the coupling between the carcass structure and the reinforcement annular structure can be provided by a second carcass layer (not shown in FIG. 1) applied in an axially outer position with respect to the first carcass layer.

[0152] An anti-abrasive strip 105 is arranged in an outer position of each reinforcement annular structure 103. Preferably each anti-abrasive strip 105 is arranged at least in an axially outer position to the reinforcement annular structure 103 extending at least between the sidewall 108 and the portion radially below the reinforcement annular structure 103.

[0153] Preferably, the anti-abrasive strip 105 is arranged so as to enclose the reinforcement annular structure 103 along the axially inner and outer and radially lower areas of the reinforcement annular structure 103 so as to interpose between the latter and the wheel rim when the tyre 100 is mounted to the rim.

[0154] 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 metallic reinforcement cords. Such reinforcing cords may have crossed orientation with respect to a direction of circumferential development of tyre 100. By “circumferential” direction it is meant a direction generally facing in the direction of rotation of the tyre.

[0155] 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 reinforcement cords, typically 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 the equatorial plane of the tyre, and coated with an elastomeric material.

[0156] A tread band 109 of elastomeric blend is applied in a position radially outer to the belt structure 106.

[0157] In some embodiments (for example tyres for motorcycle or scooter wheels), the belt structure may be absent.

[0158] Moreover, respective sidewalls 108 of elastomeric material are further applied in an axially outer position on the lateral surfaces of the carcass structure, each extending from one of the lateral edges of the tread 109 at the respective reinforcement annular structure 103, preferably made with non-staining elastomeric compound, for example the compound of example 3.

[0159] 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 FIG. 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 FIG. 1.

[0160] An under-layer 111 is arranged between the belt structure 106 and the tread band 109.

[0161] 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 sidewall 108 directly covers the lateral edge of the tread band 109.

[0162] 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.

[0163] According to the present invention, the decorative elements 120, such as coloured bands or writings, preferably with light colours, made according to the present invention are applied on the outer surface of the sidewalls 108 by hot gluing.

[0164] With reference to FIG. 2, the decorative elements 120 according to the present invention comprise a protective layer 121 with a surface 131 facing outwards exposed to the action of atmospheric agents, and an adhesive layer 123, applied to the surface 132 of the protective layer 121 facing the sidewall 108 of the tyre 100, which adheres the decorative element 120 to the sidewall 108 of the tyre 100. In the example of FIG. 2, the protective layer 121 is generally coloured by the incorporation, during the construction thereof, of a suitable coloured and covering pigment.

[0165] With reference to FIG. 3, the decorative elements 120 according to the present invention comprise a protective layer 121 with a surface 131 facing outwards exposed to the action of atmospheric agents and to the stresses deriving from contact with sidewalks and other materials, an ink layer 122 printed on the surface 132 of the protective layer 121 facing the sidewall 108 of the tyre 100, and an adhesive layer 123, applied on the ink layer 122, which adheres the decorative element 120 to the sidewall 108 of the tyre 100. In the example of FIG. 3, the protective layer is generally transparent and colourless, but it may be transparent and coloured by incorporating, during the construction thereof, a suitable coloured pigment so as to make the decorations or the printed wordings of the ink layer stand out more, by contrast of colour.

[0166] The material of the protective layer 121 is preferably made of cross-linked aliphatic polyurethane, based on polyester and/or polyether, in particular with transparent or coloured polyurethane films made by the company NTT Srl, Fagnano Olona (Italy) under the trade name X-SIDE01.

[0167] The material of the adhesive layer 123 is preferably made with pressure-sensitive adhesives (PSA), in particular the adhesives of the company Nitto Italia Srl, Milan (Italy), such as for example the adhesives 5005P, 5005T, 5005TFF, 5015P, 5015T, 5015TFF, Hyperjoint® 9004, and thermally activatable adhesives (TA—Thermo Adhesives), in particular a mixture of cross-linkable polymers including modified natural rubber (preferably epoxidised natural rubber), an ABA type block copolymer, and optionally a cross-linkable urethane rubber.

[0168] The building of the tyres 100 as described above may be carried out by assembling respective semi-finished products onto a forming drum, not shown, by at least one assembly device.

[0169] At least a part of the components intended to form the carcass structure of the tyre may be built and/or assembled on the forming drum. More particularly, the forming drum is intended to first receive the possible liner, then the carcass structure and the anti-abrasive strip. 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.

[0170] After the building of the green tyre, a moulding and vulcanisation treatment is generally carried out in order to determine the structural stabilisation of the tyre through cross-linking of the elastomeric blends , as well as to impart a desired tread pattern on the tread band and to impart any distinguishing graphic signs at the sidewalls.

[0171] The decorative elements 120 are hot applied to the sidewalls of the finished tyre downstream of the moulding and vulcanisation treatment.

[0172] The present invention will be further illustrated below by means of a number of preparation examples, which are given purely as an indication and without any limitation of the present invention.

EXAMPLE 1

[0173] Abrasion Resistance of the Protective Layer

[0174] The abrasion resistance was measured using a Taber Abrasion Tester model XHF-17 equipped with a H22 grinder based on vitrified clay and aluminium oxide particles with about 515 abrasive particles per cm.sup.2 with a load of 1 kg and frequency of rotation equal to 1 Hz (1 cycle per second).

[0175] The labels were applied to a sample of sidewall compound (as described in example 3) and were subjected to test with 100, 200 and 500 cycles.

[0176] The label of the invention consisted of the X-SIDE 01 transparent cross-linked polyurethane film of the company NTT printed with a homogeneous layer of Nylontech PLT white ink in turn covered with a layer of thermally activatable adhesive T1 (as described in example 2). The total thickness of the label I was about 140 μm.

[0177] The label of the invention I has resisted perfectly, without any sign of surface deterioration under all test conditions (100, 200, and 500 cycles), and showing incipient signs of deterioration only in the area of attachment of the grinder at the test of 200 and 500 cycles caused by the typical step effect of the test conditions.

[0178] Dynamic Mechanical Properties of the Protective Layer

[0179] The dynamic mechanical properties E′ and Tan delta of the materials were measured using a dynamic DMA EPLEXOR 500N device from NETZSCH GABO Instruments. The test conditions were: static deformation 1% (in traction), dynamic deformation ±0.1%, frequency 1 Hz, load cell 25N, temperature range from −80° C. to +70 *C, temperature increase 2° C./minute.

[0180] The dynamic mechanical properties are expressed in terms of dynamic elastic modulus (E′) and Tan delta (loss factor). The Tan delta value was calculated as the ratio between the viscous dynamic module (E″) and the dynamic elastic modulus (E′).

[0181] The test was performed with three samples of protective layer of the company NTT, as follows:

TABLE-US-00001 X-SIDE 01 transparent cross-linked polyurethane film, thickness 90 μm ± 10 μm, width 10 mm, length 20 mm (useful length between the device clamps 10 mm) X-SIDE 02 white opaque cross-linked polyurethane film with 5% by weight titanium dioxide (TiO2), thickness 90 μm ± 10 μm, width 10 mm, length 20 mm (useful length between the device clamps 10 mm) X-SIDE 03 white opaque cross-linked polyurethane film with 10% by weight titanium dioxide (TiO2), thickness 90 μm ± 10 μm, width 10 mm, length 20 mm (useful length between the device clamps 10 mm)

[0182] The results obtained, referred to 25° C., are shown in the following Table 1.

TABLE-US-00002 TABLE 1 X-SIDE 01 X-SIDE 02 X-SIDE 03 E′ (25° C.) 5-8 MPa 8-10 MPa 8-10 MPa Tandelta (25° C.) 0.40-0.34 0.30-0.240 0.30-0.240

[0183] Elastic Properties of the Protective Layer

[0184] The elastic properties were measured at 25° C. with the aid of a Zwick model Z010 dynamometer with 500 N load cell, according to the description below, using a rectangular sample (width=10 mm; length>50 mm) .

[0185] The dynamometer clamps were spaced 50 mm apart and the sample was mounted there. Subsequently, a preload of 0.2 N was imposed, moving the arm to which the upper clamp is connected (hereinafter the cross member) at a speed of 10 mm/min., so as to tension the specimen. With the optical extensometer the new distance between the clamps (L0) to be considered as the initial length of the sample was determined.

[0186] The sample was subjected to 4 deformation cycles from 0% to 12% of L0 by moving the cross member at a speed of 500 mm/minute. At the end of the 4 deformation cycles, the residual deformation was determined at the zeroing of the recorded load.

[0187] The test was performed with three samples of protective layer of the company NTT as described above. The materials X-SIDE 01, X-SIDE 02 and X-SIDE 03 characterised according to the described conditions show a residual deformation lower than 0.3% after the four 12% deformation cycles.

EXAMPLE 2

[0188] Adhesion Strength of the Adhesive Layer

[0189] The adhesion strength was measured using a Zwick model Z010 dynamometer by measuring the peeling force of two flexible adhesion elements in a T-shaped assembly according to the ISO11339 standard.

[0190] The adhesive subjected to the test is interposed between two layers of superficially untreated PET having a thickness of 50 um and a width of 20 mm and then coupled together, by screen printing, and after dissolution in a suitable solvent in the case of thermo adhesives, or lamination, in the case of pressure-sensitive adhesives. The pressure-sensitive adhesives were pressed at 50° C. and left to stand for 72 hours before measuring at 23° C. The thermo adhesives were applied at 130° C. for 60 seconds, and left to rest for 24 hours before the measurement taken at 23° C. The compositions of the thermo adhesives used are shown in the following tables 2 and 3.

TABLE-US-00003 TABLE 2 Component T1 T2 T3 T4 EKOPRENA 25 40.00 50.00  50.00  50.00 KRATON D1165P 30.00 — — 50.00 KRATON D1124 — 50.00  — — KRATON D1126 — — 50.00  — UREPAN 50 EL06G 30.00 — — — DERTOLINE PLS 40.00 40.00  40.00  40.00 Stearic acid 0.50 0.50 0.50 0.50 Rhenogran ZNO 2.00 2.00 2.00 2.00 Rhenogran ZBEC 70 3.00 3.00 3.00 3.00 Rhenogran MBTS 80 3.00 3.00 3.00 3.00 Sulphur 1.50 1.50 1.50 1.50

TABLE-US-00004 TABLE 3 Component T5 A T5 C T5 D T5 E T5 F EKOPRENA 25 40.00 40.00 40.00 40.00 40.00 KRATON D1165P 30.00 30.00 30.00 30.00 30.00 UREPAN 50 EL06G 30.00 30.00 30.00 30.00 30.00 DERTOLINE PLS 60.00 40.00 40.00 30.00 25.00 DERTOLINE MG130 — — — 10.00 — KRISTALEX 5140 — 20.00 — — 15.00 Stearic acid 0.50 0.50 0.50 0.50 0.50 Rhenogran ZNO 2.00 2.00 2.00 2.00 2.00 Rhenogran ZBEC 70 6.00 6.00 6.00 6.00 6.00 Rhenogran MBTS 80 6.00 6.00 6.00 6.00 6.00 Sulphur 3.00 3.00 3.00 3.00 3.00

TABLE-US-00005 EKOPRENA 25 epoxidised natural rubber, Felda Rubber Industries Sdn, KRATON D1165P linear styrene-isoprene-styrene block copolymer with 30% styrene, Kraton Polymers U.S. LLC, KRATON D1124 branched styrene-isoprene-styrene block copolymer with 30% styrene, Kraton Polymers U.S. LLC, KRATON D1126 radial styrene-isoprene-styrene block copolymer with 21% styrene, Kraton Polymers U.S. LLC, UREPAN 50 EL06G polyether polyurethane elastomer, based on aromatic isocyanate and polytetramethylene glycol, Rein Chemie GmbH DERTOLINE PLS Rosin-derived resin containing rosin esters with pentaerythritol, softening point 95° C., DRT France DERTOLINE MG130 Rosin-derived resin containing glycerine esters with maleic rosin, softening point 130° C., DRT France KRISTALEX 5140LV Low molecular weight hydrocarbon resin, softening point 140° C.), Eastman Chemical Company Rhenogran ZNO predispersed zinc oxide, Lanxess Rhenogran ZBEC 70 dithiocarbamate accelerator, Rhein Chemie Rhenogran MBTS 80 dibenzothiazil disulphide accelerator, Rhein Chemie

[0191] The thermo adhesive formulations were prepared in a tangential mixer (Pomini model). The mixing conditions provide for a first step (non-productive stage) in which polymers and activation system were mixed (RPM 65, 70° C.) and a subsequent completion step in which the master batch is finalised (RPM 70, 40° C.). The resins are added in solution before the adhesive is deposited.

[0192] The peeling test results are shown in the following table 4. The reported average force refers to a total displacement of 260 mm.

TABLE-US-00006 TABLE 4 Adhesive layer Medium peeling Adhesive thickness (μm) force (N) T1 60 8.0 T2 74 7.8 T3 70 8.1 T4 87 8.3 T5 A 72 15.8 T5 C 52 12.9 T5 D 57 11.7 T5 E 54 13.6 T5 F 56 9.7 BS TRANSFER 60 2.1 280/70 PA NITTO 5015T 80 4.3 NITTO 5015TFF 80 4.2 NITTO 5005TFF 50 4.2

[0193] The peeling test measured the adhesion strength to PET for all the adhesives tested, with the exception of the adhesive BS TRANSFER 280/70 PA for which the cohesion strength was measured.

EXAMPLE 3

[0194] Light Resistance of the Ink Layer

[0195] The light resistance test was performed using a Xenon chamber (supplier Q-Sun) according to the ASTM D1148 method, modified for use of UV exposure only without washing cycles.

[0196] Using the mixtures of the following table 5, rubber samples of 15×5×0.5 cm size were made, vulcanised at 170° C. for 10 minutes, representative of the sidewall of a tyre.

TABLE-US-00007 TABLE 5 Component Quantity (phr) First step Natural rubber 40 Butadiene rubber 60 Carbon black 660 50 Tackifying resin 2 Stearic acid 2 Zinc oxide 2.85 Irganox 1520 8 Second step Retardant 0.1 CBS 0.8 Sulphur 2 Natural rubber: VON BUNDIT Butadiene rubber: NIZHNEKAMSKNEFTECHIM Carbon black 660: ORION ENGINEERED CARBONS Tackifying resin: Quintone A100, Zeon Corporation Stearic acid: Temik Oleo Zinc oxide: Zincol Ossidi Irganox 1520: 4,6-bis[(octylthio)methyl]-o-cresol, BASF Retardant: N-cyclohexylthiophthalimide, Toray Fine Chemicals CBS: N-cyclohexyl-2-benzothiazyl sulphonamide, Duslo Sulphur: Zolfoindustria

[0197] All the components, except for sulphur, the retardant and the accelerator (CBS) were mixed together in an internal mixer (model Pomini PL 1.6) for about 5 minutes (first step). As soon as the temperature reached 145+5° C., the elastomeric composition was unloaded. Sulphur, the retardant and the accelerator (CBS) were then added and mixing was performed in an open roll mixer (second step).

[0198] Yellow decorative labels were applied to the resulting samples using the heat transfer method in a manual press applying a pressure of 10 kg/cm.sup.2 for 10 seconds at 120° C.

[0199] The labels were made using the X-SIDE 01 transparent cross-linked polyurethane protective layer of the company NTT of example 1 subjected to a screen printing process with Nylontech PLT Grafco ink, and subsequently coated with a layer of T5C thermo adhesive (Label 1) or T5F (Label 2).

[0200] The specimens thus obtained were exposed to a UV irradiation cycle (120 hours at 50° C.).

[0201] At the beginning and at the end of the test, the colour measurements were performed with the CLM-194 colorimeter by EOPTIS, which records the parameters L, a, b which univocally define the same.

[0202] The colorimetric results are summarised in the following table 6.

TABLE-US-00008 TABLE 6 L* a* b* Before exposure Label 1 83.43 2.35 84.74 Label 2 83.17 2.18 84.28 Mean 83.3 2.265 84.51 After exposure Label 1 80.99 3.04 80.61 Label 2 80.04 3.19 79.75 Mean 80.515 3.115 80.18

[0203] The measurement of colour resistance is defined in percentage terms with respect to the colour change before and after UV exposure by means of the following formula:

ΔE*.sub.ab=√{square root over ((L*.sub.2−L*.sub.1).sup.2+(a*.sub.2−a*.sub.1).sup.2+(b*.sub.2−b*.sub.1).sup.2)}

[0204] Using the average values of L, a and b given in table 6, the value of ΔE*ab was 5.22, which corresponds to a scarcely perceptible difference.

EXAMPLE 4

[0205] Endurance Tests on the Tyre

[0206] The endurance tests consist of a high speed test according to ISO 10191:2010 and a fatigue test.

[0207] The tyres used were Pirelli P ZERO™ 355/25ZR21 (107Y) XL rear (tyre 1), Pirelli Winter Sottozero™3 225/45R19 96V XL (tyre 2), and Pirelli P ZERO™ 255/30ZR20 (92Y) XL front (tyre 3). All tyres are made with a sidewall compound as described in example 3.

[0208] Speed

[0209] The high speed test was carried out on different samples of different tyre sizes inflated to a pressure of 2.7 bar, all decorated on the outer side with coloured labels. The test is carried out on an Indoor machine with a 1.7 m diameter drum in a conditioned environment with a controlled temperature of 25° C.

[0210] During the test, the tyre was stressed with vertical load cycles, and speeds varying over time. The overall test lasted 1 hour and 10 minutes. The following are the test conditions used:

TABLE-US-00009 Tyre Vertical load range (kg) Speed range (km/h) 1 500 ÷ 800 200 ÷ 300 2 350 ÷ 575 150 ÷ 210 3 350 ÷ 510 200 ÷ 300

[0211] At the end of the test, the covers were examined to check for defects on the labels (detachments, cracks, colour change, etc.).

[0212] Fatigue

[0213] The fatigue test was carried out on different samples of different tyre sizes, all decorated on the outer side with coloured labels.

[0214] The test was carried out on an Indoor machine with a 1.7-metre diameter drum in a conditioned environment with a controlled temperature of 25° C. The tyre was inflated to a (controlled) pressure of 3 bar and was stressed with constant vertical load and constant speed. The following are the test conditions used:

TABLE-US-00010 Tyre Vertical load (kg) Speed (km/h) 1 721 120 2 525 80 3 466 120

[0215] The test included stops for checking the tyres every 12 hours and continued until reaching 14400 km

[0216] The labels used were made with the materials of the following table 7.

TABLE-US-00011 TABLE 7 Protective layer Ink layer Adhesive layer Label 3 XSIDE 01 Nylontech T1 PLT - white Label 4 XSIDE 01 Nylontech T2 PLT - yellow Label 5 XSIDE 01 Nylontech T3 PLT - yellow Label 6 XSIDE 01 Nylontech T4 PLT - white Label 7 XSIDE 01 Nylontech T5A PLT - yellow Label 8 XSIDE 01 Nylontech T5D PLT - yellow Label 9 XSIDE 01 Nylontech T5E PLT - yellow Label 10 XSIDE 01 — BS TRANSFER 280/70 PA Label 11 XSIDE 01 — 5015TFF Label 12 XSIDE 01 — 5015TPI Label 13 XSIDE 03 — 5015TFF Label 14 XSIDE 03 — 5015TPI Label 15 XSIDE 01 Nylontech 5015TPI PLT - white Label 16 XSIDE 01 Nylontech 5015TPI PLT - yellow Label 17 XSIDE 01 Nylontech 5015TFF PLT - yellow Label 18 XSIDE 01 Nylontech HYPERJOINT PLT - yellow 9004

[0217] The labels 3-18 (in various shapes and sizes compatible with the sidewall of the tyre) were applied to the tyres 1-3 in the combinations and in the conditions shown in the following table 8, and subjected to high speed and fatigue tests. The following table 8 also shows the results of the tests expressed as follows:

[0218] High Speed Test:

[0219] A: Passed without any damage

[0220] B: Passed with some partial detachments

[0221] C: Passed with obvious detachments

[0222] Fatigue Test

[0223] A: Passed without any damage

[0224] B: Passed without detachment, with formation of bubbles

[0225] C: Passed with some partial detachments

[0226] D: Passed with obvious detachments

TABLE-US-00012 TABLE 8 Tyre Label Application High speed Fatigue 1 3 1bar 140° C. 50″ A A 1 3 1bar 140° C. 35″ A A 1 4 1bar 140° C. 50″ B — 1 4 1bar 140° C. 35″ B — 1 5 1bar 140° C. 50″ A — 1 5 1bar 140° C. 35″ A — 1 6 1bar 140° C. 50″ A — 1 6 1bar 140° C. 35″ A — 2 5 1bar 140° C. 50″ A — 2 6 1bar 140° C. 50″ A — 3 7 1bar 140° C. 40″ A — 3 8 1bar 140° C. 40″ A — 3 9 1bar 140° C. 40″ A — 1 10 2bar 50° C. — A 1 11 2bar 50° C. — A 1 12 2bar 50° C. — B 1 13 2bar 20° C. — A 1 14 2bar 20° C. — B 1 15 2bar 20° C. — B 2 16 2bar 70° C. 12″ — B 2 17 2bar 70° C. 12″ — A 2 14 2bar 70° C. 12″ — B 3 17 2bar 70° C. 12″ A — 3 18 2bar 70° C. 12″ B —

EXAMPLE 5

[0227] Endurance Tests on the Road

[0228] In view of the good results obtained and illustrated in example 4, tests were carried out with tyre engagement on the road.

[0229] The first test took place on a private circuit at an average speed of about 150 km/h. The test was performed with a Lamborghini Aventador equipped with the tyres 1 and 3 of example 4 on which labels of different composition as per table 9 were applied.

TABLE-US-00013 TABLE 9 Protective layer Ink layer Adhesive layer Label I XSIDE 01 Nylontech 5015TFF PLT - yellow Label II XSIDE 01 Nylontech HYPERJOINT PLT - yellow 9004 Label III XSIDE 01 Nylontech T5A PLT - yellow Label IV XSIDE 01 Nylontech T5C PLT - yellow Label V XSIDE 01 Nylontech T5D PLT - yellow Label VI XSIDE 01 Nylontech T5E PLT - yellow Label VII XSIDE 01 Nylontech T5F PLT - yellow

[0230] Labels I and II were applied with a pressure of 2 bar at 70° C. for 12 seconds. Labels III-VII were applied with a pressure of 1 bar at 140° C. for 60 seconds.

[0231] The dimensions of the decoration elements in height are compatible with the radial dimensions of the sidewall ranging from 0.8 cm to 2.5 cm, while the longitudinal development of the same corresponds to an arc to which a chord of dimensions ranging from 5 cm to 20 cm is subtended.

[0232] Each tyre was decorated with a maximum number of elements equal to 10. A total of 10 tyres were tested, each of which exhibited mixed solutions in terms of label sizes and related types of adhesives.

[0233] The test allowed evaluating the systems under very high mechanical stress conditions (load, speed and cornering), which led to an increase in the final sidewall temperature up to about 60° C. (external ambient temperature 13° C.). The following table 10 summarises the results obtained expressed as follows:

[0234] 3=No defect

[0235] 2=Edge/application defects

[0236] 1=Extended defects/detachments

TABLE-US-00014 TABLE 10 DIMENSIONS of labels (cm × cm) Label (1.5 × 13) (0.8 × 23) (1.2 × 5) I. 2 2 2 II. 3 3 3 III. 2 2 2 IV. 3 3 3 V. 3 3 3 VI. 3 2 3 VII. 3 3 2

[0237] All the results were considered positive in terms of adhesion: no label was detached and/or appeared damaged after the test cycle. The defects recorded were limited at the edges of the decorative elements and attributable to defects determined during the decoration step.

[0238] The second test took place on a private circuit with a distance of about 2000 km at an average speed of about 200 km/h.

[0239] The test was performed with a Porsche 991 S equipped with the Pzero 245/35ZR20 (91Y) tyres at the rear and Pzero 305 30ZR20 XL (103Y) at the front with labels of different composition as shown in table 11.

TABLE-US-00015 TABLE 11 Protective layer Ink layer Adhesive layer Label VIII XSIDE 01 Nylontech 5005TFF PLT - yellow Label IX XSIDE 01 Nylontech T5C PLT - yellow Label X XSIDE 01 Nylontech T5F PLT - yellow

[0240] Labels VIII were applied with a pressure of 2 bar at 70° C. for 12 seconds. Labels IX-X were applied with a pressure of 1 bar at 140° C. for 40 seconds.

[0241] The dimensions of the decoration elements in height are compatible with the radial dimensions of the sidewall ranging from 0.8 cm to 2.5 cm, while the longitudinal development of the same corresponds to an arc to which a chord of dimensions ranging from 5 cm to 20 cm is subtended.

[0242] Each tyre was decorated with a maximum number of elements equal to 10. A total of 4 tyres were tested (2 front and 2 rear), each of which exhibited mixed solutions in terms of label sizes and related types of adhesives.

[0243] The test allowed evaluating the systems under very high mechanical stress conditions (load and speed), which led to an increase in the final sidewall temperature up to about 55° C. (external ambient temperature 20° C.). The following table 12 summarises the results obtained expressed as follows:

[0244] 3=No defect

[0245] 2=Edge/application defects

[0246] 1=Extended defects/detachments

TABLE-US-00016 TABLE 12 DIMENSIONS of labels (cm × cm) Label (1.5 × 13) (0.8 × 23) (1.2 × 5) VIII. 3 2 2 IX. 3 3 3 X. 3 2 3

[0247] All the results were considered positive in terms of adhesion: no label was detached and/or appeared damaged after the test cycle. The defects recorded were once again at the edges of the decorative elements and attributable to defects determined during the decoration step.

[0248] The third test was carried out on public roads and highways for a total distance of about 340 km with temperatures below 0° C. (from −3° C. to −18° C.) with included a 2 days parking break at −10° C.

[0249] The test was performed with a VW TOUAREG car equipped with Pirelli Scorpion™ Winter 265/45 R20 tyres on which labels with the composition as per table 13 were applied.

TABLE-US-00017 TABLE 13 Protective layer Ink layer Adhesive layer Label XI XSIDE 01 Nylontech T1 (20 μm) PLT - white

[0250] Labels XI were applied with a pressure of 1 bar at 140° C. for 40 seconds. The following table 14 summarises the results obtained expressed as follows:

[0251] 3=No defect

[0252] 2=Edge/application defects

[0253] 1=Extended defects/detachments

TABLE-US-00018 TABLE 14 DIMENSIONS of labels (cm × cm) Label (1.5 × 13) (0.8 × 23) (1.2 × 5) XI. 2 2 2

[0254] Following the engagement of the tyres during the journey, for the described labels it was possible to highlight a good seal of the label from the point of view of the surface film and the ink, and the absence of cracks or cracking along the thickness of the decorative element.