Tyre for vehicle wheels

Abstract

Tires for vehicle wheels having reduced environmental impact and the components thereof, in particular reinforcing structural elements such as carcass structures, belt structures, flippers and chafers, include elongated reinforcing elements treated with resorcinol and formaldehyde-free cross-linkable adhesive compositions. The adhesive compositions include at least a) a rubber latex, at least b) an epoxide and at least c) a polyamine with molecular weight higher than 190 Daltons, including at least two amino groups selected from primary NH2 and secondary NH amino groups. In the structural element, these compositions confer an adhesion between cords and compounds that is comparable to, if not better than, the traditional RFL system in use in this sector. Furthermore, by suitably modifying the compound compositions in the reinforced structural elements and, possibly, also in the other elastomeric components of the tire, it is possible to manufacture tires while avoiding the use of toxic chemicals, such, as resorcinol and formaldehyde.

Claims

1. A tyre for vehicle wheels comprising: at least a reinforced structural element comprising at least an elongated reinforcing element and at least a cross-linked element adhered to said elongated reinforcing element, wherein said elongated reinforcing element comprises at least an elongated fibrous material comprising the cross-linking products of at least a cross-linkable adhesive composition comprising: at least a) a rubber latex, at least b) an epoxide, and at least c) a polyamine with molecular eight higher than 190 Daltons, comprising at least two amino groups selected from primary NH.sub.2 and secondary NH amino groups, wherein the polyamine c) is chosen from: c1) linear or branched amino terminated polyethers, c2) aminoalkylated polysaccharides, c3) aminoalkylated polyvinyl alcohols, and c4) mixtures thereof, and wherein the elongated fibrous material is chosen from rayon; lyocell; polyesters of PET, PEN, or PVA; aliphatic polyamides; aromatic polyamides; and mixtures thereof.

2. The tyre according to claim 1, further comprising: a carcass structure comprising at least one carcass layer having opposite side edges associated with respective bead structures comprising at least one annular anchoring element and at least one bead filler; and a tread band applied in a radially outer position to said carcass structure, wherein said at least one carcass layer comprises a cross-linked elastomeric material reinforced with a plurality of elongated reinforcing elements comprising the cross-linking products of at least a cross-linkable adhesive composition comprising at least a) a rubber latex, at least b) an epoxide, and at least c) a polyamine with molecular weight higher than 190 Daltons, comprising at least two amino groups selected from primary NH.sub.2 and secondary NH amino groups, wherein the polyamine c) is chosen from: c1) linear or branched amino terminated polyethers, c2)aminoalkylated polysaccharides, c3) aminoalkylated polyvinyl alcohols, and c4) mixtures thereof.

3. The tyre according to claim 2, further comprising a belt structure applied in a radially outer position to the carcass structure, said belt structure comprising at least a belt layer comprising said elongated reinforcing element comprising the cross-linking products of at least a cross-linkable adhesive composition comprising at least a) a rubber latex, at least b) an epoxide, and at least c) a polyamine with molecular weight higher than 190 Daltons, comprising at least two amino groups selected from primary NH.sub.2 and secondary NH amino groups, wherein the polyamine c) is chosen from: c1) linear or branched amino terminated polyethers, c2) aminoalkylated polysaccharides, c3) aminoalkylated alcohols, and c4) mixtures thereof.

4. The tyre according to claim 1, further comprising a reinforced structural element of bead structures, comprising at least a cross-linked elastomeric material and at least an elongated reinforcing element, wherein said elongated reinforcing element comprises the cross-linking products of at least a cross-linkable adhesive composition comprising at least a) a rubber latex, at least b) an epoxide, and at least c) a polyamine with molecular weight higher than 190 Daltons, comprising at least two amino groups selected from primary NH.sub.2 and secondary NH amino groups, wherein the polyamine c) is chosen from: c1) linear or branched amino terminated polyethers, c2) aminoalkylated polysaccharides, c3) aminoalkylated polyvinyl alcohols, and c4) mixtures thereof.

5. The tyre according to claim 1, further comprising a reinforced structural element as a bead structure protecting layer, said reinforced structural element comprising at least a cross-linked elastomeric material and at least an elongated reinforcing element, wherein said elongated reinforcing element comprises the cross-linking products of at least a cross-linkable adhesive composition comprising at least a) a rubber latex, at least b) an epoxide, and at least c) a polyamine with molecular weight higher than 190 Daltons, comprising at least two amino groups selected from primary NH.sub.2 and secondary NH amino groups, wherein the polyamine c) is chosen from: c1) linear or branched amino terminated polyethers, c2) aminoalkylated polyaccharides, c3) aminoalkylated polyvinyl alcohols, and c4) mixtures thereof.

6. The tyre according to claim 1, wherein said composition is an aqueous composition overall comprising from 2.5% to 20% by weight, of the components a) b) and c).

7. The tyre according to claim 1, wherein said composition is an aqueous composition overall comprising from 4% to 15% by weight, of the components a) b) and c).

8. The tyre according to claim 1, wherein said composition is an aqueous composition overall comprising from 5% to 10% by weight of the components a) b) and c).

9. The tyre according to claim 1, wherein said adhesive composition comprises from 2% to 17% of a) by weight, from 0.5 to 7% of b) by weight and from 0.05% to 3% of c) by weight.

10. The tyre according to claim 1, wherein said adhesive composition comprises from 3% to 12% of a) by weight, from 1% to 5% of b) by weight and from 0.1% to 2% of c) by weight.

11. The tyre according to of claim 1, wherein said adhesive composition comprises: a) a rubber latex comprising a butadiene - vinylpyridine - styrene copolymer, and/or b) a polyglycerol polyglycidyl ether.

12. The tyre according to claim 1, wherein said adhesive composition comprises a polyamine c) having molecular weight equal to or greater than 600 Daltons.

13. The tyre according to claim 1, wherein said adhesive composition and/or said elastomeric material are substantially free of resorcinol and/or free of formaldehyde and/or of cross-linking products thereof.

14. The tyre according to claim 1, wherein all reinforced and non-reinforced elastomeric components are substantially free of resorcinol and/or free of formaldehyde and/or of cross-linking products thereof.

15. A process for manufacturing a tyre for vehicle wheels, comprising: forming components of a green tyre onto at least a building drum; and shaping, moulding and vulcanizing the tyre, wherein forming at least one of the components of the green tyre comprises: making at least a reinforced structural element, said reinforced structural element comprising i) at least an elastomeric material comprising at least a diene elastomeric polymer and at least a reinforcing filler and ii) at least an elongated reinforcing element, Wherein said elongated reinforcing element comprises at least a fibrous material impregnated with at least a cross-linkable adhesive composition comprising: at least a) a rubber latex, at least b) an epoxide, and at least c) a polyamine with molecular weight higher than 190 Daltons, comprising at least two amino groups selected from primary NH.sub.2 and secondary NH amino groups, wherein the polyamine c) is chosen from: c1) linear or branched amino terminated polyethers, c2) aminoalkylated polysaccharides, c3) aminoalkylated polyvinyl alcohols, and c4) mixtures thereof, and wherein the fibrous material is chosen from rayon; lyocell; polyesters of PET, PEN, or PVA; aliphatic polyamides; aromatic polyamides; and mixtures thereof.

16. The process according to claim 15, wherein the adhesive compositions and/or elastomeric materials are free of resorcinol and/or free of formaldehyde.

17. A reinforced structural element of a tyre comprising at least an elongated reinforcing element and at least a cross-linked elastomeric material adhered to said elongated reinforcing element, wherein said elongated reinforcing element comprises at least an elongated fibrous material comprising cross-linking products of at least a cross-linkable adhesive composition comprising at least a) a rubber latex, at least b) an epoxide, and at least c) a polyamine with molecular weight higher than 190 Daltons, comprising at least two amino groups selected from primary NH.sub.2 and secondary NH amino groups, wherein the polyamine c) is chosen from: c1) linear or branched amino terminated polyethers, c2) aminoaikylated polysaccharides, c3) aminoalkvlated polyvinyl alcohols, and c4) mixtures thereof, and wherein the elongated fibrous material is chosen from rayon; lyocell; polyesters of PET, PEN, or PVA; aliphatic polyamides; aromatic polyamides; and mixture thereof.

18. The reinforced structural element according to claim 17, wherein said cross-linked elastomeric material is obtained by cross-linking a cross-linkable elastomeric material comprising at least a cross-linkable elastomeric polymer, at least a reinforcing filler, at least a methylene donor compound, at least a methylene acceptor compound and at least a vulcanizing agent, wherein said methylene acceptor compound is a phenolic resin.

19. The reinforced structural element according to claim 18, wherein said methylene acceptor compound is a novolac resin.

20. The reinforced structural element according to claim 17, wherein said cross-linkable elastomeric material comprises resorcinol in an amount lower than 0.5 phr to 0 phr.

21. The reinforced structural element according to claim 20, wherein said cross-linkable elastomeric material comprises resorcinol in an amount lower than 0.2 phr to 0 phr.

22. The reinforced structural element according to claim 20, wherein said cross-linkable elastomeric material comprises resorcinol in an amount lower than 0.1 phr to 0 phr.

23. The reinforced structural element according to claim 17, comprising a carcass structure, a belt structure, a flipper or a chafer.

24. The reinforced structural element according to claim 17, wherein adhesion between the cross-linked elastomeric material and the elongated reinforcing element, expressed as the maximum pulling force according to ASTM D4476, is at least 7 N/ mm.sup.2.

25. The reinforced structural element according to claim 17, wherein adhesion between the cross-linked elastomeric material and the elongated reinforcing element, expressed as the maximum pulling force according to ASTM D4476, is at least 7.5 N/ mm.sup.2.

26. The reinforced structural element according to claim 17, wherein adhesion between the cross-linked elastomeric material and the elongated reinforcing element, expressed as the maximum pulling force according to ASTM D4476, is at least 8 N/ mm.sup.2.

27. The reinforced structural element according to claim 17, wherein a residual degree of coating of the cords, evaluated by visual inspection following a peel test carried out according to ASTM D4393, is at least 50%.

28. The reinforced structural element according to claim 17, wherein a residual degree of coating of the cords, evaluated by visual inspection following a peel test carried out according to ASTM D4393, is at least 75%.

29. The reinforced structural element according to claim 17, wherein a residual degree of coating of the cords, evaluated by visual inspection following a peel test carried out according to ASTM D4393, is at least 90%.

30. A cross-linkable elongated reinforcing element for a tyre comprising at least a fibrous material impregnated with at least a cross-linkable adhesive composition, said composition comprising at least a) a rubber latex, at least b) an epoxide, and at least c) a polyamine with molecular weight higher than 190 Daltons, comprising at least two amino groups selected from primary NH.sub.2and secondary NH amino groups, wherein the polyamine c) is chosen from: c1) linear or branched amino terminated polyethers, c2) aminoalkylated polysaccharides, c3) aminoalkylated polyvinyl alcohols, and c4) mixtures thereof, and wherein the fibrous material is chosen from rayon; lyocell; polyesters of PET, PEN, or PVA; aliphatic polyamides, aromatic polyamides; and mixtures thereof.

31. The elongated reinforcing element according to claim 30, wherein said cross-linkable adhesive composition is substantially resorcinol-and/or formaldehyde-free.

32. A process for manufacturing a cross-linkable elongated element for tyres which comprises: providing an elongated fibrous material for reinforced structural elements for tyres; impregnating the elongated fibrous material with at least a cross-linkable adhesive composition comprising at least a) a rubber latex, at least b) an epoxide, and at least c) a polyamine with molecular eight higher than 190 Daltons, comprising at least two amino groups selected from primary NH.sub.2 and secondary NH amino groups, wherein the polyamine c) is chosen from: c1) linear or branched amino terminated polyethers, c2) aminoalkylated polysaccharides, c3) aminoalkylated polyvinyl alcohols, and c4) mixtures thereof, and wherein the elongated fibrous material is chosen form rayon; lyocell; polyesters of PET, PEN or PVA; aliphatic polyamides; aromatic polyamides; and mixtures thereof; and drying the impregnated elongated fibrous material.

33. The process according to claim 32, wherein impregnating the elongated fibrous material is performed by dipping into the cross-linkable adhesive composition.

Description

DESCRIPTION OF THE DRAWINGS

(1) Said description will be provided hereunder with reference to the accompanying drawings, which are provided for illustrative purposes only and are not therefore exhaustive, wherein:

(2) FIG. 1 illustrates a partial radial cross-section tyre for motor vehicle wheels;

(3) FIG. 2 schematically shows a radial section of a tyre for motor vehicles;

(4) In FIG. 1, a indicates an axial direction and X indicates a radial direction. For simplicity, FIG. 1 shows only a portion of the tyre, the remaining not represented portion being identical and symmetrically arranged with respect to the radial direction X. The tyre 100 for four-wheeled vehicles (motor vehicles) comprises at least one carcass structure comprising at least one carcass layer 101 having respectively opposed end flaps that are engaged with respective annular anchoring structures 102 known as bead wires, possibly associated with a bead filler 104. The tyre area comprising the bead wire 102 and the bead filler 104 form an annular reinforcing structure 103, bead structure, intended for the anchoring of the tyre onto a corresponding mounting rim, not illustrated. The carcass structure is usually of the radial type, i.e. the reinforcing elements of the at least one carcass layer 101 are located on planes comprising the axis of rotation of the tyre and substantially perpendicular to the equatorial plane of the tyre. Said reinforcement elements generally consist of textile cords, for example rayon, nylon, polyester (for example polyethylene naphthalate-PEN) cords preferably treated with a cross-linkable adhesive composition comprising at least a) a rubber latex, at least b) an epoxide, and c) a polyamine of molecular weight greater than 190 Daltons, and comprising at least two amino groups selected from primary NH.sub.2 and NH and secondary amino groups preferably with an elastomeric material comprising at least one diene elastomeric polymer and at least one reinforcing filler.

(5) Each bead structure is associated with the carcass structure by backward folding of the opposite side 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 illustrated in FIG. 1.

(6) In one embodiment, the coupling of the carcass structure and bead structure can be provided by a second carcass layer (not shown in FIG. 1) applied in an axially external position with respect to the first carcass layer.

(7) An anti-abrasive strip 105 made of elastomeric material is arranged in a position external to each bead structure 103.

(8) The carcass structure is associated with a belt structure 106 comprising one or more belt layers 106a, 106b placed in radial superposition with respect to each other and with respect to the carcass layer, having metal or textile reinforcing cords. In the event of textile cords these are preferably treated with a cross-linkable adhesive composition comprising at least a) a rubber latex, at least b) an epoxide and at least c) a polyamine of molecular weight greater than 190 Dalton, comprising at least two amino groups selected from primary and secondary NH.sub.2 and NH amino acid groups that are preferably rubberized with an elastomeric material comprising at least one diene elastomeric polymer and at least one reinforcing filler. These reinforcement cords may have a crossed orientation with respect to a direction of circumferential development of the tyre 100. Circumferential direction means a direction generally facing the direction of rotation of the tyre.

(9) In a position that is radially outermost to the belt layers 106a, 106b at least one reinforcing layer can be applied at zero degrees 106c, commonly known as 0 belt, which generally incorporates a plurality of reinforcing cords, typically textile cords, oriented in a substantially circumferential direction, thus forming an angle of a few degrees (for example an angle between about 0 and 6) with respect to the equatorial plane of the tyre, and coated with an elastomeric material following tackifying treatment preferably performed with a cross-linkable adhesive composition comprising at least a) a rubber latex, at least b) an epoxide and at least c) a polyamine of molecular weight greater than 190 Dalton, comprising at least two amino groups selected from primary NH.sub.2 and secondary NH amino groups.

(10) A tread 109 in elastomeric compound, like other semi-finished products making up the tyre 100, is applied in a position radially external to the belt structure 106.

(11) Respective sidewalls 108 in elastomeric compound are also applied in an axially external position on the side surfaces of the carcass structure, each extending from one of the side edges of the tread 109 to the level of the respective bead structure 103.

(12) The tread 109 has a rolling surface 109a, in a radially external position, intended to come in contact with the ground. Circumferential grooves, which are connected by transverse notches (not represented in FIG. 1) so as to define a plurality of blocks of various shapes and sizes distributed over the rolling surface 109a, are generally produced in this surface 109a, which for simplicity is represented smooth in FIG. 1.

(13) A substrate 111 may be arranged between the belt structure 106 and the tread 109.

(14) A strip consisting of elastomeric material 110, commonly known as mini-sidewall, can be present in the connecting area between the sidewalls 108 and the tread 109, this mini-sidewall generally being obtained by co-extrusion with the tread 109 and allowing an improvement of the mechanical interaction between the tread 109 and sidewalls 108. Preferably, the end portion of the sidewall 108 directly covers the lateral edge of the tread 109.

(15) In the case of tyres without an inner tube, a layer of rubber 112, generally known as liner, which provides the necessary impermeability to tyre inflation air, can also be envisaged in a radially inward with respect to the carcass layer 101.

(16) Tyre sidewall 108 rigidity can be improved by equipping the tyre bead structure 103 with a reinforcing layer 120 generally known as flipper or additional strip-like insert.

(17) The flipper 120 is a reinforcing layer that is wrapped around the respective bead wire 102 and bead filler 104 so as to at least partially surround, said reinforcing layer, being arranged between the at least one carcass layer 101 and the bead structure 103. Typically, the flipper is in contact with said at least one carcass layer 101 and said bead structure 103.

(18) The flipper 120 typically comprises a plurality of textile or metal cords incorporated in a cross-linked elastomeric material, when the cords are textile cords (for example aramide or rayon) they are preferably preventively treated with said cross-linkable adhesive composition.

(19) The bead structure 103 of the tyre may comprise an additional protection layer that is generally known by the term chafer 121 or protective strip and that has the function of increasing rigidity and integrity of the bead structure 103.

(20) The chafer 121 usually comprises a plurality of cords incorporated into a cross-linked elastomeric material and which are generally made of textile materials (for example aramid or rayon) preferably preventively treated with said cross-linkable adhesive composition, or metal materials (for example of steel cord).

(21) Preferably, the cross-linked elastomeric material suitable for incorporating the textile cords of said at least one carcass layer and/or said at least one belt layer and/or flipper and/or chafer layer is obtained by cross-linking a cross-linkable elastomeric material comprising at least one diene elastomeric polymer and at least one reinforcing filler.

(22) Preferably, said cross-linkable elastomeric material comprises at least one cross-linkable elastomeric polymer, at least one reinforcing filler, at least one methylene donor compound, at least one methylene acceptor compound and at least one vulcanizing agent. Even more preferably, said methylene acceptor compound is a phenolic resin, preferably a novolac.

(23) According to an embodiment not illustrated, the tyre can be a tyre for the wheels of heavy-duty vehicles, such as lorries, buses, trailers, vans, and in general for vehicles wherein the tyre is subjected to a high load.

(24) Such a tyre is preferably adapted to be mounted onto rims having a diameter equal to or greater than 17.5 inches for directional or trailer wheels. A heavy-duty transport vehicle, for example a vehicle of the M2, M3, N2, N3, O2, O3 and O4 categories according to the ECE Consolidated Resolution of the Construction of vehicles (RE3), Annex 7, Classification and definition of power-driven vehicles and trailers or of the M3, N2, N3, O3, O4 categories according to the ETRTO engineering design information (ed. 2010), the General Information, p. G15 and G16, International codes for wheeled vehicle classification as UN/ECE 29/78 and Directive 2003/37 chapter. The heavy-duty vehicles category comprises trucks, lorries, tractor-trailers, vans, buses and similar vehicles.

(25) The tyre for the wheels of heavy-duty vehicles comprises at least one carcass ply, the opposite lateral edges of which are associated with respective bead structures, the so-called bead, comprising an annular anchoring structure, known as bead wire, and at least one bead filler. The association between said at least one carcass ply and said bead structure is typically obtained folding over the opposite side edges of said at least one carcass ply around said annular anchoring structure and said at least one bead filler so as to form a flap carcass.

(26) An anti-abrasive strip made of elastomeric material can be arranged in an external position with respect to each bead structure.

(27) Said at least one carcass ply generally comprises a plurality of reinforcing elements of the carcass ply arranged substantially parallel to one another and at least partially coated with a layer of elastomeric material. These reinforcing elements of the carcass ply, in particular in the case of lorry tyres, usually comprise metal cords, preferably made of steel.

(28) Said at least one carcass ply is usually of the radial type, that is it incorporates reinforcing elements arranged in a direction substantially perpendicular to the circumferential direction.

(29) A belt structure is applied in a radially external position with respect to said at least one carcass ply.

(30) The belt structure comprises at least two belt bearing layers that are radially superimposed and incorporate a plurality of reinforcing belt elements, typically metal cords, preferably made of steel. The belt structure may also comprise a reinforcing layer at zero degrees applied, for example, in a radially external position with respect to the second bearing belt layer.

(31) The metal cords used in the layers of the belt structure, and in particular those used in the layers of bearing belt layers, comprise a plurality of wires.

(32) The wires of the metal cords used in the belt structure (and typically also in other tyre reinforcing layers) are preferably steel wires NT (normal tensile), HT (high tensile), SHT (Super High Tensile) or UHT (ultra high tensile). Typically, these steel wires have a carbon content of less than about 1%. Preferably, the carbon content is greater than or equal to about 0.7%. The wires are typically coated with brass or other corrosion-resistant coating (for example Zn/Mn).

(33) A tread is applied circumferentially in a radially external position with respect to said belt structure. Externally, the tread has a rolling surface suitable for coming into contact with the ground.

(34) Some circumferential grooves, which can be connected by transverse notches (not represented), define a tread pattern which comprises a plurality of ribs and/or blocks of various shapes and sizes, distributed on the rolling surface.

(35) A sidewall is applied externally on the carcass ply. The sidewall extends in an axially external position, from the bead structure to the tread.

(36) A substrate is arranged at the level of the area, where the side edges of the tread connect with the sidewall.

(37) An elastomeric layer, generally known as a liner, which provides the necessary impermeability to tyre inflation air, can be provided at a radially inward position with respect to the carcass ply.

(38) The rigidity of the tyre sidewall for heavy-duty vehicles can be improved by equipping the tyre bead structure with a reinforcing layer generally known as flipper or additional strip-like insert.

(39) The flipper typically comprises a plurality of textile or metal cords incorporated in a cross-linked elastomeric material, when the cords are textile (for example aramide or rayon) they are preferably preventively treated with said cross-linkable adhesive composition.

(40) The bead structure of tyres for heavy-duty vehicles may comprise an additional protection layer that is generally known by the term chafer or protection strip and which has the function of increasing the rigidity and integrity of the structure.

(41) The chafer usually comprises a plurality of cords preferably incorporated in a cross-linked elastomeric material and which are generally made of textile materials (for example aramid or rayon) preventively tackified by means of tackifying treatment preferably performed with said cross-linkable adhesive composition or in metal materials (for example steel cords).

(42) Preferably, the cross-linked elastomeric material suitable for producing the flipper and/or the chafer is obtained by cross-linking a cross-linkable elastomeric material comprising at least one diene elastomeric polymer and at least one reinforcing filler. Preferably, said cross-linkable elastomeric material comprises at least one cross-linkable elastomeric polymer, at least one reinforcing filler, at least one methylene donor compound, at least one methylene acceptor compound and at least one vulcanizing agent. Even more preferably, said methylene acceptor compound is a phenolic resin, preferably a novolac.

(43) In FIG. 2, 100 is globally indicates a tyre for the wheels of motor vehicles.

(44) The tyre 100 defines an equatorial plane XX and a rotation axis Z (not shown in the figure). A circumferential direction (indicated in the figures by the arrow f oriented in the direction of rotation of the tyre) and an axial direction perpendicular to the equatorial plane XX are also defined.

(45) The tyre 100 comprises a carcass structure 2 including at least one carcass ply 3, made of elastomeric material and comprises a plurality of reinforcing elements arranged parallel to each other.

(46) The carcass ply 3 is engaged, by means of its opposite circumferential edges, to at least one bead structure 9.

(47) In particular, the opposite side edges 3a of the carcass ply 3 are folded back around the annular anchoring structures 4, known as bead wires.

(48) A tapered bead 5, which occupies the space defined between the carcass ply 3 and the corresponding side edge 3a of the folded carcass ply 3, is applied on the axially outer peripheral edge of bead wires 4.

(49) The area of the tyre comprising the bead wire 4 and the filling 5 forms a bead structure 9, the so-called bead, intended for anchoring the tyre onto a corresponding mounting rim, not shown.

(50) The anti-abrasive strip 15 is arranged in a position outside of each bead structure 9.

(51) The reinforcing elements included in the carcass ply 3 preferably comprise textile cords, selected among those usually adopted in the package of tyre carcasses, for example nylon, rayon, PET, PEN, with elementary wire having a diameter of between 0.35 mm and 1.5 mm, incorporated in a cross-linked elastomeric material said textile cords are preferably preventively treated with said cross-linkable adhesive composition.

(52) In an embodiment that is not illustrated, the carcass structure presents its opposite lateral edges associated with no fold over to particular bead structures provided with two annular inserts. A filler made of elastomeric material can be arranged in an axially external position to the first annular insert. The second annular insert is, instead, arranged in a axially external position to the end of the carcass ply. Lastly, a further filler can be envisaged, in an axially external position to said second annular insert, and not necessarily in contact therewith, which terminates the production of the bead structure.

(53) Typically a belt structure 6 comprising one or more belt layers placed radially superimposed with respect to each other and with respect to the carcass layer, having reinforcing cords metal or textiles, is typically circumferentially applied in a radially external position of the carcass structure 2.

(54) The belt structure 6 is circumferentially superimposed with a tread 8 on which, following a moulding operation carried out simultaneously with the vulcanization of the tyre, longitudinal and/or transverse grooves are typically produced, arranged to define a desired tread.

(55) The tyre 100 can comprise a pair of sidewalls laterally applied from opposite sides of said carcass structure 2.

(56) The tyre sidewall rigidity for motor vehicles can be improved by equipping the bead structure 9 with a reinforcing layer generally known as flipper 16 or additional strip-like insert.

(57) The flipper 16 is wrapped around the respective bead wire 4 and the bead filler 5 so as to at least partially surround them, said reinforcing layer being arranged between the at least one carcass ply 3 and the bead structure 9.

(58) The bead structure 9 of tyres for motor vehicles may comprise an additional protection layer that is generally known by the term chafer 17 or protection strip and which has the function of increasing rigidity and integrity of the bead structure 9.

(59) The flipper and/or the chafer usually comprise a plurality of textile cords (for example aramid or rayon) incorporated in a cross-linked elastomeric composition and preferably preventively treated with said cross-linkable adhesive composition.

(60) Preferably, the tyre 100 for motor vehicles presents a straight section characterized by a high transverse curvature.

(61) In particular, the tyre 100 for motor vehicles has a section height H measured on the equatorial plane, between the height of the tread and the rim diameter, identified by the reference line a, passing through the tyre beads.

(62) The tyre 100 for motor vehicles further has a width C defined by the distance between the laterally opposite ends E of the tread itself, and a curvature defined by the particular value of the ratio between the distance f of the tread crown from the line through the ends E of the tread itself, measured on the equatorial plane of the tyre and the aforementioned width C. The ends E of the tread can be formed with an edge.

(63) Tyres having high curvature are tyres which present a curvature ratio of f/C no less than 0.2, preferably f/C0.25, for example 0.28. Preferably, such a curvature ratio f/C is not in excess of 0.8, preferably f/C0.5.

(64) The tyres preferably present particularly low sidewalls. In other words, tyres with low or low profile sidewalls are tyres wherein the sidewall height ratio (Hf)/H is less than 0.7, more preferably less than 0.65, for example 0.6.

(65) In a preferred embodiment, the motor vehicle tyre is intended to be mounted onto the rear wheel having cord dimensions substantially comprised between 100 and 260 mm.

(66) In a preferred embodiment, the tyre is intended to be mounted onto the front wheel of a motor vehicle having cord dimensions substantially comprised between 80 and 140 mm.

(67) Preferably, the distance (f) between the radially external point of the tread and the line passing through the laterally opposite ends of the tread itself of the front tyre can be substantially comprised between 45 and 65 mm. Preferably, the transverse/cord curve ratio (f/C) can be substantially comprised between 0.35 and 0.70, even more preferably between 0.35 and 0.60. Preferably, the (total height)/cord (H/C) ratio is substantially between 0.6 and 1.

(68) In the event of tyres without inner tube, the carcass structure 2 is typically coated on its inner walls by a sealing layer, or so-called liner, essentially consisting of a layer of elastomeric material that is impermeable to air, adapted to ensure the hermetic seal of the tyre itself once inflated.

(69) Preferably, the belt structure 6 consists of a layer 7 which presents a plurality of circumferential windings 7a axially arranged side by side, formed by a rubberized cord or by a narrow band comprising a number of rubberized cords (preferably two to five), spirally wound with a substantially zero angle (typically between 0 and 5) with respect to the equatorial plane X-X of the tyre.

(70) The belt structure preferably extends substantially over the entire crown portion of the tyre.

(71) In a preferred embodiment, the belt structure 6 can consist of at least two radially superimposed layers, each consisting of elastomeric material reinforced with cords arranged parallel to each other. The layers are arranged in such a way that the cords of the first belt layer are oriented obliquely with respect to the equatorial plane of the tyre, whereas the cords of the second layer also present oblique orientation, but symmetrically crossed with respect to the cords of the first layer (the so-called cross-belt).

(72) In both cases, the cords of the belt structure are generally textile or metal cords. In the case of textile cords, for example rayon, nylon, polyester (for example polyethylene naphthalate-PEN) and aramids, these are incorporated in a cross-linked elastomeric material. Said textile cords are preferably preventively treated with said cross-linkable adhesive composition.

(73) Preferably, the cross-linked elastomeric material suitable for incorporating the textile cords of said at least one carcass layer and/or said at least one belt layer and/or the flipper and/or the chafer is obtained by cross-linking a cross-linkable elastomeric material comprising at least one diene elastomeric polymer and at least one reinforcing filler.

(74) Preferably, said cross-linkable elastomeric material comprises at least one cross-linkable elastomeric polymer, at least one reinforcing filler, at least one methylene donor compound, at feast one methylene acceptor compound and at least one vulcanizing agent. Even more preferably, said methylene acceptor compound is a phenolic resin, preferably a novolac.

(75) Preferably, the tyre 100 may comprise a layer of elastomeric material 10 placed between said carcass structure 2 and said belt structure 6.

(76) The building of tyres 100 as described above, can be implemented by means of the assembly of respective semi-finished products on a building drum, not illustrated, by at least one assembling device.

(77) At least a part of the components intended to form the carcass structure of the tyre can be constructed and/or assembled on the building drum. More in particular, the building drum lends itself to first receiving any liner, subsequently the carcass structure and the anti-abrasive strip. Subsequently, devices that are not illustrated coaxially engage one of the annular anchoring structures around each of the end flaps, placing an outer sleeve comprising the belt structure and the tread in a coaxially centred position around the cylindrical carcass sleeve and shape the carcass sleeve on the basis of a toroidal configuration by means of a radial expansion of the carcass structure, so as to determine the application thereof against a radially inner surface of the outer sleeve.

(78) Following the assembly of the green tyre, a moulding and vulcanization treatment is performed with a view to determining the structural stabilization of the tyre through cross-linking of the elastomeric compounds and to impart a desired tread pattern on the tread and to stamp any distinctive graphic signs at the level of the sidewalls.

(79) The present invention is further illustrated in the following experimental part, proposed purely by way of a non-limiting example.

(80) Experimental Part

(81) In the present experimental part the adhesion between cordspre-treated with the present cross-linkable adhesive composition or with compositions of the prior artand compounds, as described in detail hereunder, was evaluated with the following tests: adhesion test (H-test, by pull-out), measuring the force required to pull out the cord from the block of elastomeric material of the sample following vulcanisation, performed according to the method ASTM D4776 (maximum pull out force); the specific vulcanization conditions and the measured data are recorded in Table 3a. peel test (peel or strap adhesion) performed according to the ASTM D4393 method, in the version Strap Peel Adhesion From Single Cord, with a specimen width of 20 mm, with measurement of the maximum force applied and an assignment of a sample observation score following tearing, as shown in Table 1:

(82) TABLE-US-00001 TABLE 1 Mark Degree of coating 5 100% 4 up to 75% 3 up to 50% 2 up to 25% 1 100% de-rubberized cords

(83) The maximum score of 5 indicates an excellent adhesion between elastomeric material and cords, which remain completely covered with rubber following tearing. In this case sample breakage only takes place within the mass of the rubber. Conversely, a score of 1 indicates a poor adhesion and the total removal of the rubber cords following the tear.

(84) The vulcanization conditions of the specimens and the test data are recorded in table 4.

(85) The following tackifying compositions were prepared according to traditional procedures: Traditional epoxide-based pre-activation composition 1; traditional RFL-based composition 2; comparative compositions 3-7 according to the teachings of WO2005/080481; compositions 8-13 according to the invention,
with the components and amounts (in grams) shown in the following tables 2a and 2b below:

(86) TABLE-US-00002 TABLE 2a Compositions (comparative) C-1 C-2 C-3 C-4 C-5 C-6 C-7 Ingredients Water 980 792.3 930 930 930 923.4 931.3 Resorcinol resin/ 27.8 formaldehyde Formaldehyde 6.9 Ammonia 10.3 Dry 1637 46.7 46.7 46.7 46.7 38.8 Latex (a) Epoxide (b) 20 19.6 19.6 19.6 26.2 26.2 Amine (c) 3.7 3.7 3.7 3.7 3.7 Pip DtA DCH99 DCH99 DCH99 Solids content 2% 21% 7% 7% 7% 7.7% 7% Amine/Epoxide 0.19 0.19 0.19 0.14 0.14 (Amine + 0.50 0.50 0.50 0.64 0.77 Epoxide/Latex) Example C-1 C-1 C-2 C-3 (tab 3 and 4) C-4 C-4

(87) TABLE-US-00003 TABLE 2b Compositions (invention) I-8 I-9 I-10 I-11 I-12 I-13 Ingredients Water 930 926.5 930 930 930 930 Resorcinol resin/ formaldehyde- Formaldehyde Ammonia Dry Latex (a) 46.7 46.7 46.7 46.7 46.7 46.7 Epoxide (b) 17.5 17.5 19.6 17.5 17.5 17.5 Amine (c) 5.8 9.3 3.7 5.8 5.8 5.8 JD230 JD230 JD230 JSD231 JD400 JSD401 Solids content 7% 7% 7% 7% 7% 7% Amino/Epoxide 0.33 0.53 0.19 0.33 0.33 0.33 (Amine + 0.50 0.57 0.50 0.5 0.5 0.5 Epoxide/Latex) Example I-1. I-2 I-4 I-5 I-6 (tab 3 and 4) I-3
Keys Table 2a and 2b Total weight of the compositions: 1,000 g Solids content: % by weight (dry) Amino/Epoxide and (Amino+Epoxide)/Latex: are weight ratios of the components (dry) Resorcinol resin/Formaldehyde (pre-condensed): Penacolite R50, 50% aqueous solution, marketed by Indspec. Latex a): Pliocord VP106S styrene/vinylpyridine latex marketed by Eliokem Epoxide (b): for all the compositions except composition 1, GE500 Polyglycerol polyglycidyl ether, for composition 1: GE100 glycerol glycidyl ether; marketed by Raschig Amino c): the below are considered amines (according to the prior art) and polyamines c) according to the invention, in particular: Pip=Piperazine (marketed by Dow Chemical Company), DtA=Dytek A: 2-methylpentamethyenediamine, DCH99=Dytek DCH99; 1,2-diaminocyclohexane (marketed by Invista); JD230=Jeffamine D230 (primary diamine of formula I, wherein X about 2.5, pm about 230 pm), JD400=Jeffamine D400 (primary diamine of formula I, wherein X about 6.1, pm about 430); JSD231=Jeffamine SD-231 (secondary diamine derived from Jeffamine D-230, pm about 315); JSD401=Jeffamine SD-401 (secondary diamine derived from Jeffamine D-400, pm about 515); (marketed by Huntsman)

(88) Given an equal solids content, the compositions according to the invention (8-13) proved is to be more stable than those (4-7) comprising amines in accordance with the teachings of WO2005/080481, in particular it was observed that: the composition 4 is unusable as unstable (rapid flocculation); the composition 5 was fairly stable in the laboratory at 7 C. but not at room temperature and under conditions of transport and industrial use; it was employed in the preparation of the samples, however, it does not have suitable characteristics for use in actual industrial conditions; the composition 6 resulted unstable: the rapid coagulation of the components was in fact observed at room temperature. We did not proceed further in the preparation of the samples; the composition 7 resulted unstable: it had in fact already hardened after one day in the laboratory at 7 C., and did not therefore appear usable at an industrial level. We did not proceed further in the preparation of the samples; on the other hand, the compositions 8-13 according to the invention proved to be stable for at least 8 days, in some cases for at least 30 days, thus being particularly advantageous for industrial application.

(89) Some cords made of Aramid 16702 (31.531.5) Twaron 1000 marketed by Teijin Twaron 1000 were then impregnated by dipping (single or double, as specified in the tables 3 and 4 below) with the compositions recorded in tables 2a and 2b, in particular with the compositions 1 and 2 (comparative example C-1 traditional RFL treatment), with the compositions 3 and 5 (comparative example C-2 with piperazine and C-3 with 1,2-diaminocyclohexane, according to the teachings of WO2005/080481), and with the compositions 8, 9, 11, 12 and 13 (Examples from I-1 to 1-5 according to the invention).

(90) In particular, the raw cords were dipped at room temperature in a bath having the compositions recorded in the table and dried for 120 s at 150 C. under an imposed load of 8.5 N in a forced air circulation stove; the drying step is followed by a cross-linking step for 90 s at 240 C., with constant tension always equal to 8.5 N.

(91) The cords thus treated were coupled with the compound 1 (traditional compound with resorcinol) and 2 (resorcinol-free compound)the detailed compositions of which are recorded in table 5to give representative samples of structural reinforced tyre elements. The samples were prepared in accordance with the guidelines as set out in ASTM 04776 and ASTM D4393 and subjected to adhesion evaluation, in accordance with the respective procedures as per ASTM standards.

(92) In particular, table 3a records the average force values (adhesion data, H-test) on 9.52 mm specimens measured according to standard ASTM D4776 and expressed in Newton, with the standard deviation values in brackets. The vulcanization conditions of the samples are of 30 minutes at 151 C.

(93) TABLE-US-00004 TABLE 3a Example (C/I) C-1 C-2 C-3 I-1 I-2 Composition 1 + 2 3 5 8 9 epoxide, RFL Piperazine DCH99 JD230 JD230 Treatments double single double single single Compound 1 201 (8) 163 (4) 180 (5) 180 (7) 168 (10) Compound 2 196 (20) 187 (11) 195 (6) 172 (4)

(94) The diameter of the cords is equal to 0.67 mm, therefore by normalizing with respect to the interface between cord and compoundan area that is given by *cord diameter*embedded length=0.67 mm*9.52 mm=6.38 mm.sup.2the values shown in table 3b, expressed in N/mm.sup.2, are obtained:

(95) TABLE-US-00005 TABLE 3b Example (C/I) C-1 C-2 C-3 I-1 I-2 Composition 1 + 2 3 5 8 9 epoxide, RFL Piperazine DCH99 Jef D230 Jef D230 Treatments double single double single single Compound 1 10.0 8.1 9.0 9.0 8.4 Compound 2 9.8 9.3 9.7 8.6

(96) Example C: comparatives. I: invention

(97) As can be seen from the data shown in tables 3a and 3b. it is evident that the compositions according to the invention (Example I-1 and I-2) achieve excellent levels of adhesion especially with Compound 2 and with only a single dipping of the cords. These adhesion values obtained with the present compositions are at least comparable to the high standards represented by the RFL system currently in use (Example C-1), nevertheless presenting undoubted advantages in terms of stability and safety even with respect to alternative compositions (Example C-2 and C-3). Moreover, since the application process does not require any pre-activation, it is particularly rapid and economically competitive.

(98) Table 4 below records the strength values (expressed in N/20 mm, with the respective standard deviation values in brackets) necessary for obtaining the 180 opening of a peeling specimen (strap peeling) obtained by means of the superimposition of two layers of co-vulcanized rubberized reinforcement, as described in standard ASTM D4393.

(99) In particular, the individual rubberized layers were obtained by deposition on a rotating drum, preventively coated with a layer of the selected compound, of continuous cords with a constant pitch, respectively treated according to the prior art and according to the invention. The subsequent combination with regular pitch of multiple coils produced a desired rubberized cord fabric (Ar 1670/2 31.531.5) with density equal to 70 plies/dm and thickness of 0.90 mm.

(100) Two layers of this fabric were superimposed along the main direction of the cords and co-vulcanized for 30 min at 170 C., taking care to introduce, for about the first 2 cm in the transverse direction to the cords, a sheet of inert film (for instance Mylar) which, once the vulcanized compound has been obtained, constitutes a guide zone for the subsequent opening of the specimen in dynamometer.

(101) The vulcanized composite thus obtained was divided into 2-cm wide strips with an automatic cutter, in line with the main direction of the cords.

(102) These strips were separated, starting from the guide zone, by traction using a Zwick Roell 2020 dynamometer at a speeds equal to 50 mm/min.

(103) The maximum force (in N/20 mm) required to open the thus obtained sample at 180 C., was then recorded.

(104) The visual appearance of the delamination surface between the two separated layers was evaluated following traction, with expression of the degree of coating of the cords by the compound on a scale of 1 to 5 as shown in Table 1. In particular, 5 represents a complete coating of the cords by the compound (100%), 1 represents the delamination at the cord/compound interface; the intermediate stages are shown in table 1. The cords are the same cords of the previous samples. The specific treatment conditions thereof and the compounds used are recorded in table 4.

(105) TABLE-US-00006 TABLE 4 Example (C/I) C-4 C-4 I-3 I-3 I-4 I-4 I-5 I-5 I-6 I-6 Composition 1 + 2 8 11 12 13 Epoxide. JD230 JSD231 JD400 JSD401 RFL Treatments double single single single single Force Mark Force Mark Force Mark Force Mark Force Mark Compound 1 108 (5) 4 76 (2) 3 75 (8) 3 70 (5) 3 68 (7) 3 Compound 2 75 (9) 3 112 (9) 4
Keys Table 4 Force: expresses the maximum value of force applied to tearing (N/20 mm) (standard deviation in brackets) Mark: expresses the appearance of the sample following tearing (scale from 1 to 5 as shown in table 1)

(106) In the peeling test, all samples evidenced cohesive failure within the rubber with variable residual amount of elastomeric material on the cords depending on the type of elastomeric material and composition adopted, indicative of a good adhesion.

(107) According to this test, when coupled with the resorcinol-free compound (compound 2), the cords treated with the composition of the invention adherefollowing a single treatmenteven more of the current industry benchmark standard represented by the traditional RFL system (cords dipped in a first epoxy bath then in the second RFL bath and coupled with a traditional compound comprising resorcinol) (112 vs. 108).

(108) On a visual judgment of the specimen following tearing, the two systems are comparable (score of 4), while if we compare the results of the specimens obtained with the resorcinol-free compound 2, the tear resistance according to the invention was even better (4 vs 3).

(109) In conclusion, the composite of the present invention is an excellent substitute substantially free of the formaldehyde and resorcinol of the traditional system in current use, a system which on the other hand comprises resorcinol both at the level of the treated cords and at the level of compounds, with serious ecological and health implications.

(110) The compositions of the compounds used in the tests are shown in table 5 below:

(111) TABLE-US-00007 TABLE 5 Compound 1 2 Natural rubber STR20 P93 (Thaiteck Rubber. Thailand) 100 90 in mixture with polyisoprene SKI-3 (Nizhnekamsk. Russia) (90:10) Styrene Butadiene Rubber SBR1500 (KER 1500-Dwory) 10 Carbon black N326 (Cabot Corp.) 55 55 N-(1.3-dimethylbutyl)-N-phenyl-p-phenylenediamine 2 2 (6PPD Santoflex Flexsys); Vivatec 200 MES oil (H&R) 2.5 2.5 Stearic Acid Radiacid 444 (Oleon) 1.5 1.5 Zinc oxide green seal (Zincol Ossidi) 5 5 Tackifier SP 1068 (SI Group) 2 2 Phenolic resin Alnovol PN760 (CYTEC) 3 Resorcinol 1.3 HMMM hexamethoxymethylmelamine (Cyrez 963. 1.9 1.9 Cytec) CBS N-cyclohexyl-2-benzothiazyl-sulphenamide 1.5 1.5 (Vulkacit CZ. Lanxess) Sulphur 67% CRYSTEX OT 33 AS (Flexsys) 4.78 5.52

(112) The kinetics and the mechanical properties of the compounds used in the tests are shown in table 6.

(113) TABLE-US-00008 TABLE 6 Compound 1 2 Viscosity ML(1 + 4) (at 100 C.) 58 60 Rheometric analysis ML[dN m] 2.39 2.64 MH[dN m] 30.35 29.72 TS2[min] 1.07 1.16 T90[min] 2.87 4.31 Tensile tests Ca0.5 [MPa] 1.9 2.5 Ca1 [MPa] 3.48 4.16 Ca3 [MPa] 15.51 15.8 CR [MPa] 20.58 19.86 AR [%] 407.86 395.0 Tensile strength [J/cm.sup.3] 37.04 35.89 Hardness [IRHD] at 23 C. 87.0 86.4 Elastic yield [%] at 23 C. 55.0 54.0
Viscosity

(114) Mooney viscosity is based on measurement of the torque required to maintain in rotation a rotor dipped in the mixture to be evaluated and was performed according to ASTM D1646.

(115) The test parameters are the preheating time when the rotor is stationary and the rotation time before acquiring the necessary torque value for rotation. The standard test is performed at a temperature of 100 C. with 1 min of preheating and 4 min testing (identified with the initials ML (144). The speed of rotation is 0.209 rad/s (2 rev/min). The Mooney scale is directly proportional to the torque applied to the rotor with the following relation: 1 Mooney unit 0.083 N.m The average travelling speed gradient during the test is in the order of magnitude of 1 s.sup.1.

(116) Rheometric Analysis

(117) The rheometric analysis was performed according to ISO 6502 using a MDRMoving Die Rheometerunder constant frequency isothermal conditions and deformation amplitude(10 Hz; +/3 of deformation) at 170 C. for 30 minutes,)

(118) We measured the values of minimum torque (ML) expressed in Newtons*meters and maximum torque (MH), expressed in Newton*meter and an intermediate time of vulcanization which provide guidance on the kinetics of the reaction at the temperature of measurement.

(119) Ts2 expresses the scorch time i.e. the time required in order to obtain a torque value equal to ML+0.22 (Newton. metro).

(120) T90 expresses the vulcanization time in % i.e. the time required to obtain a torque value equal to ML+(90/100)*(MHML) TS2=time at 170 C. required to achieve an increase of two rheometric units (ML+0.22 (Newton. metro)) measured with the MDRMoving Die Rheometer; T90=time at 170 C. required to achieve 90% of the final torque value measured by the MDRMoving Die Rheometer;
Static Mechanical Test

(121) The tensile test according to IS037-UN16065 generates a strain curve towards deformation. The instrument used was a dynamometer equipped with optical extensometer since the displacement of the moving crosshead is not directly proportional to the elongation of the sample in the gauge length. The test was performed on Dumbbell specimens vulcanized for 10 min at 170 C.

(122) The static mechanical properties (CA05 load at 50% elongation. CA1 load at 100% elongation and CA3 load at 300% elongation), according to standard UNI 6065, were measured at different elongations (50%, 100%, 300%); the Load and Elongation at Break were also respectively measured CR and AR% on samples of the above-mentioned elastomeric materials, vulcanized at 170 C. for 10 minutes.

(123) Characteristic points of the tensile test: Ca 05=50% deformation strain (MPa) Ca 1=100% deformation strain (MPa) Ca 3=300% deformation strain (MPa) CR=Strain at break (MPa) AR=Deformation at break (%) Strength=Tensile strength [J/cm.sup.3]
Hardness

(124) The hardness test was performed by measuring the sinking of a penetrator in the material once a regulated load had been applied. The hardness in IRHD degrees (at 23 C.) was measured according to standard ISO 48:2007 on samples of the above-mentioned elastomeric materials vulcanized at 170 C. for 10 minutes.

(125) The laboratory specimen was 8 mm thick. The method used was international Hardness (IRHD) with Reference standard: ISO48.

(126) R.E.=Elastic yield % measured by the torsional pendulum (Zerbinii pendulum) in accordance with ISO 4662

(127) The compound 2, characterized by the absence of resorcinol and formaldehyde. contributes to further improve the adhesion with the cords treated with the present compositions as evidenced by the data reported in tables 3a, 3b and 4.

(128) In conclusion, the use of the compositions according to the invention in the manufacture of tyres, in particular in the treatment of fibrous materials of the reinforcing elements is particularly advantageous, given equal performance with the classic RFL system, because it is simpler, quicker and, on the whole, more economical. It also allows the reductionby using specific compoundsand even completely avoidance of the use of resorcinol and free formaldehyde in the production of tyres, with undoubted advantages for the health of the operators and the environment.

(129) High Speed Integrity Test

(130) A high speed integrity test was conducted according to Regulation UNECE 30, Rev. 3-Amendment 2, Annex 7 Procedure for load/speed performance tests.

(131) The test was performed on UHP tyres 255/35 R20 97Y XL and with a chamber internal pressure of 3.6 bar at 0, by rotating the tyre on a drum of 2 m of diameter under a load of 501 Kg.

(132) The speed of the tyre was brought from 0 to 270 km/h in 10 min and then it was set as follows: a) 20 min at constant speed of 270km/h b) 10 min at constant speed of 280km/h c) 10 min at constant speed of 290km/h d) 10 min at constant speed of 300km/h

(133) The test was considered successful if the tyre survived all the steps without incurring in damages or showing defects, such as tearings or ruptures that may occur in different portions of the tyre.

(134) The comparative sample tyre (tyre 1) incorporated a flipper reinforced with cords of Ar 1670/2 31,531,5 F80, cords which had been pre-treated with the conventional double dipping into RFL-based compositions 1 and 2 (see Table 2a and the following description of the pre-treatment) and had been coupled with compound 1 (traditional compound with resorcinol, Table 5) according to conventional manufacturing methods.

(135) The sample tyre according to the invention (tyre 2) incorporated a flipper reinforced with cords of Ar 1670/2 31,531,5 F80, cords which had been pre-treated with a single dipping into composition 8 (Table 2b) and had been coupled with the compound 2 (resorcinol free compound, Table 5) according to conventional manufacturing methods.

(136) Both the comparative sample tyre (tyre 1) and the sample tyre according to the invention (tyre 2) were able to pass the integrity test limit as described above, with no defects at the end of the test.

(137) In conclusion, this rather demanding integrity test showed that the tyres of the inventionespecially when they comprise, in the reinforced components, both the optimized compounds and the cords treated with the present compositionshad excellent integrity results comparable with those achieved with conventional tyres based on the RFL system. Advantageously, however the present tyres have a lower content or are substantially free of the cross-linking products of resorcinol.