Tyre having sidewall comprising plurality of layers

Abstract

The invention relates to a tire having a sidewall comprising a plurality of layers. The present invention relates to a tire comprising a tread, at least one carcass ply, a pair of bead portions, a pair of sidewalls, wherein each of the pair of sidewalls extends between the tread and a respective one of the pair of bead portions. At least one sidewall of the pair of sidewalls includes a first circumferential sidewall layer and a second circumferential sidewall layer extending between the first sidewall layer and an adjacent carcass ply along an axially inner side of the first sidewall layer.

Description

Technical Field

[0001] The present invention relates to a tyre comprising a sidewall comprising at least a first sidewall layer and a second sidewall layer. Furthermore, the present invention relates to a method for manufacturing such a tyre. Background Art

[0002] Modern pneumatic tires should meet many different performance requirements, such as advanced grip, low rolling resistance and / or high wear resistance. For some applications, it is also desirable that the tire be particularly robust, such as in the case of off-road applications. For example, such applications may require a robust tread, belt and / or casing construction. Although progress has been made in the development of robust tires, such as for off-road applications, over the past few decades, there is still significant room for improvement. Summary of the invention

[0003] In a first aspect, the present invention relates to a tire comprising a tread, at least one carcass ply, a pair of bead portions, and a pair of sidewalls, wherein each sidewall of the pair of sidewalls extends between the tread and a corresponding bead portion of the pair of bead portions. At least one sidewall of the pair of sidewalls comprises a first circumferential sidewall layer and a second circumferential sidewall layer extending between the first sidewall layer and an adjacent carcass ply along an axially inner side of the first sidewall layer.

[0004] In a second aspect, the invention relates to a method of manufacturing a tyre comprising a pair of sidewalls, wherein the method comprises the step of providing at least one sidewall of the pair of sidewalls with a first sidewall layer and a second sidewall layer.

[0005] The present invention discloses the following embodiments:

[0006] 1. A tire comprising a tread, at least one carcass ply, a pair of bead portions, and a pair of sidewalls, wherein each sidewall of the pair of sidewalls extends between the tread and a corresponding bead portion of the pair of bead portions,

[0007] wherein at least one of the pair of side walls comprises:

[0008] a first circumferential sidewall layer, and

[0009] A second circumferential sidewall layer extends axially inwardly of the first sidewall layer between the first sidewall layer and an adjacent carcass ply.

[0010] 2. The tire of embodiment 1, wherein the second sidewall layer extends over a radial height in the range of 50% to 90% of the total radial height of the first sidewall layer.

[0011] 3. The tire of embodiment 1, wherein the tire further comprises at least one pair of chafers including a first chafer in contact with one or more of the first sidewall layer and the second sidewall layer.

[0012] 4. The tire according to embodiment 3, wherein the first sidewall layer at least partially covers the first chafer on the axially outer side of the first chafer.

[0013] 5. The tire of embodiment 4, wherein the second sidewall layer contacts the first chafer at a radially outer end portion of the first chafer.

[0014] 6. The tire of embodiment 5, wherein the second sidewall layer overlaps the first chafer by at most 5% of the total radial height of the first chafer.

[0015] 7. A tire according to embodiment 1, wherein the second sidewall layer has a thickness of one or more of the following at least along 90% of its extension from its radially outer end to its radially inner end: i) 50% to 300% of the thickness of the adjacent carcass ply; and ii) 0.5 mm to 5 mm.

[0016] 8. The tire of embodiment 1, wherein the first sidewall layer extends further toward a radially innermost position of the tire than the second sidewall layer.

[0017] 9. The tire of embodiment 1, wherein the radially innermost end of the first sidewall layer extends to a radial position so as to cover at least 50% of the total radial height of an adjacent chafer of the tire.

[0018] 10. The tire of embodiment 1, wherein the radially outermost ends of the first sidewall layer and the second sidewall layer are disposed between the radially innermost belt layer and the carcass ply of the tire.

[0019] 11. A tire according to embodiment 1, wherein the at least one sidewall extends to a position between an axially outer portion of the radially innermost belt layer of the tire and at least one carcass ply, and wherein the axially inner end of the second sidewall layer extends farther along the carcass ply toward the equatorial plane of the tire than the axially inner end of the first sidewall layer.

[0020] 12. Tire according to embodiment 1, wherein the first sidewall layer is at least twice as thick as the second sidewall layer over at least 80% of its extension in radial height.

[0021] 13. The tire of embodiment 1, wherein the first sidewall layer comprises a first rubber composition and the second sidewall layer comprises a second rubber composition different from the first rubber composition.

[0022] 14. The tire according to embodiment 13, wherein the first rubber composition has one or more of the following:

[0023] a relative volume loss at least 5% less than the relative volume loss of the second rubber composition as measured by drum abrasion according to ASTM 5963;

[0024] Less than 80 mm as measured by drum abrasion according to ASTM 5963 3 Relative volume loss;

[0025] a tensile strength at least 5% greater than the tensile strength of the second rubber composition;

[0026] Tensile strength of at least 12 MPa;

[0027] at least 10 phr more silica than the second rubber composition; and

[0028] At least 5 phr less oil than the second rubber composition.

[0029] 15. The tire according to embodiment 13, wherein the second rubber composition has one or more of the following:

[0030] a crack growth rate that is at least 5% lower than the crack growth rate of the first rubber composition;

[0031] Crack growth rate less than 0.009 mm / min;

[0032] Less than 10 phr of silicon dioxide; and

[0033] Greater than 10 phr of oil.

[0034] 16. A tire according to embodiment 13, wherein the tire further has a pair of chafers, wherein the first chafer adjacent to the first sidewall layer and the second sidewall layer has a third rubber composition different from the first rubber composition and the second rubber composition, and wherein the third rubber composition contains at least 70 phr of one or more fillers selected from carbon black and silica.

[0035] 17. The tire according to embodiment 16, wherein the third rubber composition comprises 10 to 50 phr of polybutadiene rubber, 10 to 40 phr of one or more of natural rubber and synthetic polyisoprene, and 10 to 40 phr of styrene butadiene rubber.

[0036] 18. The tire according to embodiment 13,

[0037] The first rubber composition comprises:

[0038] 40 to 60 phr of polybutadiene rubber;

[0039] 60 phr to 40 phr of one or more of natural rubber and synthetic polyisoprene;

[0040] 0.1 to 40 phr of carbon black;

[0041] 20 phr to 60 phr of silicon dioxide; and

[0042] 0phr to 8phr of oil.

[0043] 19. The tire according to embodiment 13, wherein the second rubber composition comprises:

[0044] 40 to 75 phr of polybutadiene rubber;

[0045] 60 phr to 25 phr of one or more of natural rubber and synthetic polyisoprene;

[0046] 30 to 60 phr of carbon black;

[0047] 0 to 15 phr of silicon dioxide; and

[0048] 10phr to 25phr of oil.

[0049] 20. The tire according to embodiment 1, wherein the tire is a pneumatic tire comprising one or more of the following:

[0050] at least two carcass plies;

[0051] Up to three carcass plies;

[0052] Exactly two belt cord layers;

[0053] a tread radially covering the radially outer end of the sidewall;

[0054] a fabric-reinforced carcass ply; and

[0055] Fabric-reinforced covering. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The present invention will now be described by way of example and with reference to the accompanying drawings, in which:

[0057] Figure 1 is a schematic cross-sectional view of a tire according to a first embodiment of the present invention; and

[0058] Figure 2 is a schematic cross-sectional view of another tire according to the second embodiment of the present invention. Specific implementation plan

[0059] In a first aspect, the invention relates to a tire comprising a tread, at least one carcass ply, a pair of bead portions, optionally a pair of chafers, and a pair of sidewalls, wherein each sidewall of the pair of sidewalls extends between the tread and a respective one of the pair of bead portions. At least one sidewall of the pair of sidewalls comprises a first circumferential sidewall layer and a second circumferential sidewall layer extending (at least partially) axially inwardly of the first sidewall layer between the first sidewall layer and an adjacent carcass ply.

[0060] Such a sidewall construction with at least two layers can provide a more robust tire. It is also possible to provide a sidewall with different properties, such as by having each layer have a different rubber composition and / or geometry. This allows the overall sidewall properties to be adjusted to meet the desired performance and / or robustness criteria.

[0061] In one embodiment, the second sidewall layer extends over one or more of the following: a radial height corresponding to at least 50%, preferably at least 60%, of the total radial height of the first sidewall layer; a radial height corresponding to at most 90% of the total radial height of the first sidewall layer. Thus, each sidewall layer extends not only in the (entire) circumferential direction, but also perpendicularly to the circumferential direction.

[0062] In this context, the length and / or thickness measurements are taken of the tire in the uninstalled state (ie not mounted on a rim) without inflation pressure and load.

[0063] In another embodiment, the tire further comprises at least one pair of chafers, comprising a first chafer in contact with one or more of the first sidewall layer and the second sidewall layer. In particular, one chafer of the pair of chafers is provided on each lateral / axial side of the tire. The tire may also comprise, for example, two pairs of chafers, wherein one chafer of each pair is provided on each lateral / axial side of the tire.

[0064] In yet another embodiment, the first sidewall layer at least partially covers the first chafer on the axially outer side of the first chafer, or in other words overlaps the first chafer.

[0065] In yet another embodiment, at least the radially inner half or the radially inner two thirds (preferably of the total radial height) of the first sidewall layer is visible on the tire surface, or in other words, on the tire outer surface.

[0066] In yet another embodiment, the second sidewall layer contacts the first chafer at a radially outer end portion of the first chafer.Preferably, the second sidewall layer does not overlap the first chafer.

[0067] In yet another embodiment, the second sidewall layer overlaps the first chafer by at most 5%, preferably at most 2% of the total radial height of the first chafer.

[0068] In yet another embodiment, the second sidewall layer (along 90% of its extension from its radially outer end to its radially inner end) has a thickness in the range of 50% to 300% (preferably 80% to 250%) of the adjacent carcass ply. Alternatively, the second sidewall layer has a thickness in the range of 105% to 300% of the adjacent carcass ply. In particular, the carcass ply is preferably the radially outermost carcass ply determined in the equatorial plane of the tire. The thickness is determined perpendicular to the surface of the second sidewall layer and / or the carcass ply. In addition or alternatively, the thickness may be in the range of 0.5 mm to 5 mm, or 1.5 mm to 5 mm, or 1 mm to 5 mm, or 1 mm to 2 mm, or preferably 0.5 mm to 2 mm.

[0069] In yet another embodiment, determined perpendicularly to the axially outer surface (in radial height) of the first sidewall layer, the first sidewall layer is thicker in radial height than the second sidewall layer over at least 80% of its extension, preferably at least 2 times thicker.

[0070] In yet another embodiment, the tire further comprises a belt layer portion, comprising one or more belt layers (the belt layer portion is preferably radially arranged between the tread and at least one carcass ply in a crown region of the tire), wherein the at least one sidewall extends to a position (radially) between an axially outer portion of the radially innermost belt layer and at least one carcass ply, and wherein optionally, the (axially inner) end of the second sidewall layer extends further along the carcass ply toward the equatorial plane of the tire than the (axially inner) end of the first sidewall layer.

[0071] In yet another embodiment, the first sidewall layer extends further toward the radially innermost position of the tire than the second sidewall layer. In other words, the first sidewall layer overlaps and / or extends beyond the second sidewall layer toward the corresponding bead portion of the tire.

[0072] In yet another embodiment, the radially innermost end of the first sidewall layer extends to a (radially inner) position covering at least (preferably radially outer) 50% of the total radial height of an adjacent chafer of the tire.

[0073] In yet another embodiment, the radially outermost end of the first sidewall layer and the radially outermost end of the second sidewall layer are disposed between the radially innermost belt layer and the carcass ply of the tire.

[0074] In yet another embodiment, a majority (preferably at least 70%) of the axially outer length of the first sidewall layer between its radially upper end and its radially lower end is visible on the outer surface of the tire, and / or the second sidewall layer is not visible at all from any position outside the tire. In other words, the second sidewall layer extends completely within the tire, for example, below the axially outer surface of the tire.

[0075] In yet another embodiment, the first sidewall layer comprises a first rubber composition and the second sidewall layer comprises a second rubber composition different from the first rubber composition.

[0076] In yet another embodiment, the first sidewall layer and / or the second sidewall layer have no reinforcement or reinforcing element. In particular, the first sidewall layer and / or the second sidewall layer are preferably not reinforced with textile cords and / or metal cords / wires. Alternatively or in addition, the first sidewall layer and / or the second sidewall layer, or the first rubber composition and / or the second rubber composition are non-coated rubber compositions coated with fabrics, wires and / or cords, respectively.

[0077] In yet another embodiment, the first rubber composition has one or more of the following:

[0078] The relative volume loss as measured by drum abrasion testing according to ASTM 5963 or an equivalent method is at least 5%, preferably at least 10% lower than the relative volume loss of the second rubber composition;

[0079] Also measured by drum wear test according to ASTM 5963 or equivalent method less than 90mm 3 , or less than 80mm 3 , or less than 70mm 3 (and optionally higher than 40mm 3 )’s relative volume loss;

[0080] A tensile strength at least 10% higher, and optionally up to 200% or 100% higher than the tensile strength of the second rubber composition;

[0081] Tensile strength in the range of 12MPa (or 13MPa) to 20MPa;

[0082] at least 10 phr, preferably at least 20 phr and / or at most 65 phr more silica than the second rubber composition; and

[0083] At least 5 phr less, or preferably at least 10 phr less, oil than the second rubber composition.

[0084] Tensile strength and / or elongation at break are determined by ring specimen testing based on ASTM D412 or equivalent method, and the percentages are elongation, strain, respectively; tensile strength is the stress at break; elongation is the elongation at break in percent.

[0085] In yet another embodiment, the second rubber composition has one or more of the following:

[0086] a crack growth rate that is at least 5% lower, or at least 10% lower, or preferably at least 30% lower and / or up to 90% lower than the crack growth rate of the first rubber composition;

[0087] A crack growth rate of less than 0.009 mm / min, preferably less than 0.005 mm / min, and optionally greater than 0.001 mm / min;

[0088] Tensile strength ranges from 5MPa to 11MPa;

[0089] less than 10 phr of silica, preferably less than 5 phr of silica; and

[0090] More than 10 phr of oil, preferably up to 30 phr of oil.

[0091] Crack growth and / or crack growth rate are measured herein according to ASTM D813 or an equivalent method. This method is sometimes also referred to as the DeMattia crack growth test.

[0092] In yet another embodiment, the tire further has a pair of chafers, wherein a first chafer of the pair of chafers adjacent to the first sidewall layer and the second sidewall layer has a third rubber composition (e.g., a first chafer rubber composition) that is different from each of the first rubber composition and the second rubber composition. The third rubber composition includes at least 70 phr of a filler, the filler including or selected from one or more of carbon black and silica. Thus, the chafer has a relatively high amount of filler compared to the amount of filler in the first and / or second rubber compositions.

[0093] In yet another embodiment, the third rubber composition includes 10 to 50 phr of polybutadiene rubber, 10 to 40 phr of one or more of natural rubber and synthetic polyisoprene, and 10 to 40 phr of styrene butadiene rubber.

[0094] In yet another embodiment, the first rubber composition comprises one or more of: 40 to 60 phr of polybutadiene rubber; 60 to 40 phr of one or more of natural rubber and synthetic polyisoprene; 0.1 to 40 phr (preferably 10 phr or 20 to 40 phr) of carbon black; 20 to 60 phr of silica; 0 to 10 phr (preferably to 8 or 6 phr) of oil.

[0095] In yet another embodiment, the second rubber composition comprises one or more of: 40 to 75 phr of polybutadiene rubber; 60 to 25 phr of one or more of natural rubber and synthetic polyisoprene; 30 to 60 phr (preferably 40 phr) of carbon black; 0 to 15 phr (preferably 0 to 5 or 10 phr) of silica; and 10 to 25 phr of oil.

[0096] In yet another embodiment, the second rubber composition comprises at least 5 phr, preferably at least 10 phr more polybutadiene rubber than the first rubber composition.

[0097] In yet another embodiment, the second rubber composition comprises at least 5 phr, preferably at least 10 phr less natural rubber and / or synthetic polyisoprene than the first rubber composition.

[0098] In yet another embodiment, the second rubber composition comprises at least 5 phr less filler and / or at least 5 phr more oil than the first rubber composition.

[0099] In yet another embodiment, the tire is one or more of a pneumatic tire, a passenger tire, an off-road tire, and a radial tire.

[0100] In yet another embodiment, the tire comprises one or more of the following: at least two carcass plies; at most three carcass plies; two carcass plies, three carcass plies, two belt cord layers or belt layers, a tread radially covering the radially outer ends of the sidewalls; preferably a fabric-reinforced overlay ply; and one or more fabric-reinforced carcass plies. Preferably, the one or more fabric-reinforced layers contain no metal reinforcement.

[0101] Various rubber compositions are mentioned herein, which may have various ingredients. Some examples are mentioned below.

[0102] In another embodiment, the rubber composition may include at least one or more and / or one or more additional diene-based rubbers, such as one or more of styrene butadiene rubber (SBR, e.g., S-SBR or E-SBR), natural rubber (NR), synthetic polyisoprene (PI), and polybutadiene rubber (BR).

[0103] In one embodiment, synthetic or natural polyisoprene rubber may be used. Synthetic cis-1,4-polyisoprene and natural rubber are known per se to those skilled in the rubber art. In particular, the cis-1,4-microstructure content may be at least 90%, and typically at least 95% or even higher.

[0104] In one embodiment, cis-1,4-polybutadiene rubber (BR) is used. Suitable polybutadiene rubbers can be prepared, for example, by organic solution polymerization of 1,3-butadiene. BR can be conveniently characterized, for example, by having a cis-1,4-microstructure content of at least 90% ("high cis" content) and a glass transition temperature (Tg) of -95°C to -110°C. Suitable polybutadiene rubbers are commercially available, such as from The Goodyear Tire & Rubber Company. 1207, 1208, 1223 or 1280. These high cis-1,4-polybutadiene rubbers can be synthesized, for example, using a nickel catalyst system comprising a mixture of (1) an organonickel compound, (2) an organoaluminum compound, and (3) a fluorine-containing compound, as described in U.S. Pat. No. 5,698,643 and U.S. Pat. No. 5,451,646, which are incorporated herein by reference.

[0105] The glass transition temperature or Tg of an elastomer represents the glass transition temperature of the respective elastomer in its uncured state. The glass transition temperature of an elastomeric composition represents the glass transition temperature of the elastomeric composition in its cured state. Tg is determined as the peak midpoint by differential scanning calorimetry (DSC) at a heating rate of 20°C / min according to ASTM D3418 or an equivalent method.

[0106] As used herein and in accordance with conventional practice, the term "phr" means "parts by weight per 100 parts by weight of the respective material of rubber or elastomer". In general, using this convention, a rubber composition contains 100 parts by weight of rubber / elastomer. The claimed composition may contain other rubbers / elastomers not explicitly mentioned in the claims, as long as the phr value of the claimed rubber / elastomer meets the claimed phr range and the amount of all rubbers / elastomers in the composition results in a total of 100 parts of rubber. Unless otherwise indicated, the terms "compound" and "composition" and "formulation" are used interchangeably herein. The terms "rubber" and "elastomer" are also used interchangeably herein.

[0107] In another embodiment, one of the rubber compositions comprises from 1 to 80 phr, or from 5 to 80 phr, of a resin, preferably having a glass transition temperature, Tg, greater than 20°C. The Tg of the resin is measured as a peak midpoint at a heating rate of 10°C / minute by differential scanning calorimetry (DSC) according to ASTM D6604 or an equivalent method. Preferably, the resin has a softening point greater than 70°C as measured by ASTM E28, which may sometimes be referred to as the ring and ball softening point. In one embodiment, the rubber composition comprises from 10 to 60 phr, or from 20 to 60 phr, or from 30 to 60 phr of the resin, particularly where the rubber composition is a tread cap rubber composition.

[0108] In another embodiment, the resin is selected from coumarone-indene resins, petroleum hydrocarbon resins, terpene polymers / resins, styrene / alpha methyl styrene resins, terpene phenol resins, rosin derived resins, and copolymers and / or mixtures thereof.

[0109] The coumarone-indene resin preferably contains coumarone and indene as monomer components constituting the resin backbone (main chain). Monomer components other than coumarone and indene that can be incorporated into the backbone are, for example, methylcoumarone, styrene, alpha-methylstyrene, methylindene, vinyltoluene, dicyclopentadiene, cyclopentadiene and dienes such as isoprene and piperylene. The coumarone-indene resin preferably has a softening point (as measured by the ring and ball method) of 10° C. to 160° C. Even more preferably, the softening point is 30° C. to 100° C.

[0110] Suitable petroleum resins include both aromatic and non-aromatic types. Several types of petroleum resins are available. Some resins have low unsaturation and high aromatic content, while some are highly unsaturated, and others are completely free of aromatic structures. The differences in the resins are mainly due to the olefins in the raw materials from which the resins are generated. Conventional derivatives in such resins include any C5 species (olefins and dienes containing an average of 5 carbon atoms), such as cyclopentadiene, dicyclopentadiene, dienes, such as isoprene and piperylene, and any C9 species (olefins and dienes containing an average of 9 carbon atoms), such as vinyl toluene, alpha methyl styrene and indene. Such resins are made from any mixture formed by the C5 and C9 species mentioned above, and are referred to as C5 / C9 copolymer resins. Petroleum resins with softening points of 10°C to 120°C are generally available. Preferably, the softening point is 30 to 100°C.

[0111] In one embodiment, the C5 resin is an aliphatic resin made from one or more of the following monomers: 1,3-pentadiene (eg, cis or trans), 2-methyl-2-butene, cyclopentene, cyclopentadiene, and dicyclopentadiene.

[0112] In another embodiment, the C9 resin is a resin made from one or more aromatic monomers preferably selected from the group consisting of indene, methylindene, vinyltoluene, styrene, and methylstyrene (eg, alpha-methylstyrene).

[0113] In yet another embodiment, the C9 modified resin is a resin (eg, a C5 resin) that has been modified or functionalized with one or more aromatic monomers preferably selected from indene, methylindene, vinyltoluene, styrene, and methylstyrene (eg, α-methylstyrene).

[0114] The terpene resin preferably comprises a polymer of at least one of limonene, α-pinene, β-pinene and δ-3-carene. Such resins are available with a softening point of 10°C to 135°C.

[0115] Terpene-phenol resins can be obtained by copolymerization of phenol monomers with terpenes such as limonene, pinene and delta-3-carene.

[0116] Representative of resins derived from rosin and its derivatives are, for example, gum rosin, wood rosin and tall oil rosin. Gum rosin, wood rosin and tall oil rosin have similar compositions, although the amounts of the components of the rosin may differ. Such resins may be dimerized, polymerized or disproportionated. Such resins may be in the form of esters of rosin acid and polyols such as pentaerythritol or diols.

[0117] Styrene / alpha methylstyrene resins are considered herein to be (preferably relatively short chain) copolymers of styrene and alpha methylstyrene having a styrene / alpha methylstyrene molar ratio in the range of about 0.05 to about 1.50. In one aspect, such resins can be suitably prepared, for example, by cationic copolymerization of styrene and alpha methylstyrene in a hydrocarbon solvent. Thus, the contemplated styrene / alpha methylstyrene resins can be characterized, for example, by their chemical structure, i.e., their styrene and alpha methylstyrene content, and by their glass transition temperature, molecular weight, and molecular weight distribution.

[0118] In one embodiment, the resin is partially or fully hydrogenated.

[0119] In one embodiment, the rubber composition includes oil, such as processing oil. Oil can be included in the rubber composition as a filler oil commonly used to fill elastomers. Oil can also be included in the rubber composition by directly adding the oil during rubber compounding. The oil used can include both the filler oil present in the elastomer and the process oil added during compounding. Suitable oil can include various oils known in the art, including aromatic oils, paraffinic oils, naphthenic oils, vegetable oils and low PCA oils, such as MES, TDAE, SRAE and heavy naphthenic oils. Suitable low PCA oils can include those with a polycyclic aromatic hydrocarbon content of less than 3 weight % as measured by the IP346 method. The procedure of the IP346 method can be found in Standard Methods for Analysis & Testing of Petroleum and Related Products and British Standard 2000 Parts, 2003, the 62nd edition, the Institute of Petroleum, United Kingdom publishes. Some representative examples of vegetable oils that can be used include soybean oil, sunflower oil, canola oil (rapeseed oil), corn oil, coconut oil, cottonseed oil, olive oil, palm oil, peanut oil and safflower oil. Soybean oil and corn oil are generally preferred vegetable oils. The glass transition temperature Tg of the oil is measured as peak midpoint at a heating rate of 10°C / minute by differential scanning calorimetry (DSC) according to ASTM E1356 or an equivalent method.

[0120] In one embodiment, the rubber composition comprises silica, particularly if it is a tread rubber composition. Silica can be, for example, pyrolytic / fumed silica or precipitated silica. In a preferred embodiment, precipitated silica is used. Silica can be characterized, for example, by having a BET surface area measured using nitrogen. In one embodiment, the BET surface area can be 40 to 600 square meters per gram. In another embodiment, the BET surface area can be 50 to 300 square meters per gram. The BET surface area is determined according to ASTM D6556 or an equivalent method and is described in Journal of the American Chemical Society, Vol. 60, p. 304 (1930). Silica can also be characterized by having a dibutyl phthalate (DBP) absorption value of 100 cm3 / 100g to 400 cm3 / 100g or 150 cm3 / 100g to 300 cm3 / 100g, which is determined according to ASTM D2414 or an equivalent method. The silica may have an average final particle size of 0.01 to 0.05 microns, for example, as determined by electron microscopy, although the size of the silica particles may be even smaller or may be larger. The silica may be used in the present invention in a range of, for example, 1 to 120 phr, preferably 10 to 70 phr. Various commercially available silicas may be used, for example, by way of example only and not limitation, silicas commercially available from PPG Industries under the Hi-Sil trademark and with references 210, 315G, EZ160G, etc.; silicas available from Solvay with references such as Z1165MP and Premium 200MP, etc.; and silicas available from Evonik AG with references such as VN2 and Ultrasil 6000GR, 9100GR, etc.

[0121] Some non-limiting examples of pre-treated silicas (i.e., silicas that have been pre-surface treated with silanes) that may be used in the practice of the present invention include, but are not limited to, silicas that have been pre-treated with mercaptosilanes. 255LD and LP (PPG Industries) silica, and as an organosilane bis (triethoxysilylpropyl) polysulfide (Si69) with The product of the reaction between VN3 and silica 8113 (Degussa), and 6508, from PPG Industries 400 Silica, from PPG Industries 454 Silica and from PPG Industries 458Silicon dioxide.

[0122] In one embodiment, the rubber composition may include carbon black. Representative examples of such carbon black include, for example, N110, N121, N134, N220, N231, N234, N242, N293, N299, N315, N326, N330, N332, N339, N343, N347, N351, N358, N375, N539, N550, N582, N630, N642, N650, N683, N754, N762, N765, N774, N787, N907, N908, N990, and N991 grades.

[0123] In one embodiment, the rubber composition may contain a sulfur-containing organosilicon compound or silane. Examples of suitable sulfur-containing organosilicon compounds have the following formula:

[0124] Z-Alk-S n -Alk-Z I

[0125] Where Z is selected from:

[0126]

[0127] Where R 1 is an alkyl group of 1 to 4 carbon atoms, a cyclohexyl group or a phenyl group; R 2 is an alkoxy group of 1 to 8 carbon atoms or a cycloalkoxy group of 5 to 8 carbon atoms; Alk is a divalent hydrocarbon of 1 to 18 carbon atoms, and n is an integer of 2 to 8. In one embodiment, the sulfur-containing organosilicon compound is 3,3'-bis(trimethoxy or triethoxysilylpropyl)polysulfide. In one embodiment, the sulfur-containing organosilicon compound is 3,3'-bis(triethoxysilylpropyl)disulfide and / or 3,3'-bis(triethoxysilylpropyl)tetrasulfide. Therefore, for Formula I, Z can be

[0128]

[0129] Where R 2 is an alkoxy group of 2 to 4 carbon atoms, or 2 carbon atoms; Alk is a divalent hydrocarbon of 2 to 4 carbon atoms, or 3 carbon atoms; and n is an integer of 2 to 5, or 2 or 4. In another embodiment, suitable sulfur-containing organosilicon compounds include compounds disclosed in U.S. Pat. No. 6,608,125. In one embodiment, the sulfur-containing organosilicon compound includes 3-(octanoylthio)-1-propyltriethoxysilane CH3(CH2)6C(=O)-S-CH2CH2CH2Si(OCH2CH3)3, which can be used as NXT TMAvailable from Momentive Performance Materials. In another embodiment, suitable sulfur-containing organosilicon compounds include those disclosed in U.S. Patent Application Publication No. 2003 / 0130535. In one embodiment, the sulfur-containing organosilicon compound is Si-363 from Degussa. The amount of the sulfur-containing organosilicon compound in the rubber composition may vary depending on the level of other additives used. The amount of the compound may be from 0.5phr to 20phr, particularly in the case of tread rubber compositions. In one embodiment, the amount will be from 1phr to 10phr.

[0130] It is readily understood by those skilled in the art that rubber compositions can be compounded by methods commonly known in the rubber compounding field, such as mixing various sulfur-vulcanizable component rubbers with various commonly used additive materials, such as sulfur donors, curing aids such as activators and retarders, and processing additives such as oils, resins including tackifying resins and plasticizers, fillers, pigments, fatty acids, zinc oxide, waxes, antioxidants and antiozonants and peptizers. As known to those skilled in the art, according to the intended use of sulfur-vulcanizable and sulfur-vulcanized materials (rubbers), the above-mentioned additives are selected and usually used in conventional amounts. Some representative examples of sulfur donors include elemental sulfur (free sulfur), disulfide amines, polymerized polysulfides and sulfur olefin adducts. In one embodiment, sulfur-vulcanizing agents are elemental sulfur. Sulfur-vulcanizing agents can be used, for example, in an amount of 0.5phr to 8phr or 1.5phr to 6phr. If used, the typical amount of tackifying resins includes, for example, 0.5phr to 10phr, typically 1phr to 5phr. If used, a typical amount of a processing aid comprises, for example, 1 phr to 50 phr (this may particularly include oils). If used, a typical amount of an antioxidant may, for example, comprise 1 phr to 5 phr. Representative antioxidants may be, for example, diphenyl-p-phenylenediamine, etc., such as those disclosed in The Vanderbilt Rubber Handbook (1978), pages 344 to 346. If used, a typical amount of an antiozonant may, for example, comprise 1 phr to 5 phr. If used, a typical amount of a fatty acid (which may include stearic acid) may, for example, comprise 0.5 phr to 3 phr. If used, a typical amount of a wax may, for example, comprise 1 phr to 5 phr. Microcrystalline wax is generally used. If used, a typical amount of a peptizing agent may, for example, comprise 0.1 phr to 1 phr. Typical peptizing agents may, for example, comprise pentachlorothiophenol and dibenzamidodiphenyl disulfide.

[0131] Accelerators can be preferably but not necessarily used to control the time and / or temperature required for vulcanization, and to improve the properties of vulcanized rubber. In one embodiment, a single accelerator system, i.e., a primary accelerator, can be used. One or more primary accelerators can be used in a total amount of 0.5phr to 4phr or 0.8phr to 1.5phr. In another embodiment, a combination of a primary accelerator and an auxiliary accelerator can be used, and the auxiliary accelerator is used in a smaller amount, such as 0.05phr to 3phr, to activate and improve the properties of the vulcanized rubber. The combination of these accelerators can be expected to produce a synergistic effect on the final properties, and is better to a certain extent than the effect produced by using any accelerator alone. In addition, delayed action accelerators can be used, which are not affected by normal processing temperatures, but produce satisfactory solidification at ordinary vulcanization temperatures. Vulcanization retarders can also be used. Accelerators of suitable types that can be used for the present invention are, for example, amines, disulfides, guanidines, thioureas, thiazoles, thiurams, sulfenamides, dithiocarbamates / salts and xanthates / salts. In one embodiment, the primary accelerator is a sulfenamide. If a secondary accelerator is used, the secondary accelerator may be, for example, a guanidine, dithiocarbamate or thiuram compound. Suitable guanidines include diphenylguanidine and the like. Suitable thiurams include tetramethylthiuram disulfide, tetraethylthiuram disulfide and tetrabenzylthiuram disulfide.

[0132] The mixing of the rubber composition can be achieved by methods known to those skilled in the art of rubber mixing. For example, the ingredients can be mixed in at least two stages, i.e., at least one non-productive stage, followed by a productive mixing stage. The final curing agent comprising a sulfur-vulcanizing agent can be mixed in the final stage, which is generally referred to as a "productive" mixing stage, wherein the mixing is generally carried out at a temperature or final temperature lower than one or more mixing temperatures of the previous one or more non-productive mixing stages. The terms "non-productive" and "productive" mixing stages are well known to those skilled in the art of rubber mixing. In one embodiment, the rubber composition can be subjected to a thermomechanical mixing step. The thermomechanical mixing step generally includes mechanical processing in a mixer or extruder for a period of time, such as being suitable for producing a rubber temperature of 140° C. to 190° C. The appropriate duration of the thermomechanical processing varies with the operating conditions and the volume and properties of the components. For example, the thermomechanical processing can be 1 to 20 minutes.

[0133] The vulcanization of the pneumatic tire of the present invention can be carried out, for example, at conventional temperatures of 100° C. to 200° C. In one embodiment, the vulcanization is carried out at a temperature of 110° C. to 180° C. Any conventional vulcanization method can be used, such as heating in a press or mold, heating with superheated steam or hot air. Such tires can be built, shaped, molded and cured by various methods that are known and will be apparent to those skilled in the art.

[0134] In a second aspect, the invention relates to a method for manufacturing a tire comprising a pair of sidewalls, wherein the method comprises the step of providing at least one of the pair of sidewalls with (or comprising) a first sidewall layer and a second sidewall layer. In other words, at least one sidewall comprises a first sidewall layer and a second sidewall layer.

[0135] In one embodiment, one or more of the first sidewall layer and the second sidewall layer are provided by one or more of extrusion, calendaring, and tape lamination.

[0136] In another embodiment, the first sidewall layer is extruded simultaneously with the second sidewall layer.

[0137] In yet another embodiment, the tire is built on a tire building drum.

[0138] In yet another embodiment, the first sidewall layer and the second sidewall layer are extruded separately and optionally assembled and / or attached to each other on a tire building drum.

[0139] In yet another embodiment, the first sidewall layer and the second sidewall layer are attached to each other, optionally substantially parallel to each other.

[0140] In yet another embodiment, the first sidewall layer is laminated to at least one strip of the second sidewall layer, optionally on a tire building drum.

[0141] In yet another embodiment, the first sidewall layer is applied to the second sidewall layer, wherein, optionally, the first sidewall layer is extruded and the second sidewall layer (covered by the first sidewall layer) is strip laminated, preferably on a tire building drum.

[0142] In another embodiment, the first sidewall layer and / or the second sidewall layer are coextruded with the chafer.

[0143] In yet another embodiment, the chafer and the second sidewall layer are arranged side by side with each other as viewed in a cross section perpendicular to the extrusion direction.

[0144] In yet another embodiment, the chafer overlaps the second sidewall layer by less than 5% of the total width of the extruded chafer, viewed in a cross section perpendicular to the extrusion direction.

[0145] In yet another embodiment, the first sidewall layer overlaps the chafer by at least 10% of the chafer width, viewed in a cross section perpendicular to the extrusion direction.

[0146] In yet another embodiment, the first sidewall layer, the second sidewall layer (and optional chafer) together form an extruded (preferably flat) strip or band, and / or tire sidewall assembly.

[0147] In yet another embodiment, the first sidewall layer and / or the second sidewall layer (and optionally the chafer) are coextruded with a shoulder pad, the shoulder pad preferably being in contact with the second sidewall layer. Preferably, the shoulder pad is extruded simultaneously with the first sidewall layer, the second sidewall layer and optionally the chafer. Preferably, the shoulder pad is extruded on the side of the second sidewall layer opposite to the chafer, viewed in a cross section perpendicular to the extrusion direction.

[0148] In yet another embodiment, the tyre is a tyre according to the first aspect, and optionally according to one or more of its embodiments.

[0149] In yet another embodiment, a method of building a tire comprises one or more of the following steps:

[0150] applying one or more carcass plies, optionally to an innerliner;

[0151] Applying two (bead) apex rubber cores (e.g., to one or more carcass plies);

[0152] applying two beads and optionally folding one or more carcass plies around the beads;

[0153] applying at least one pair of chafers;

[0154] applying a pair of sidewalls, wherein at least one of the pair of sidewalls comprises a first sidewall layer and a second sidewall layer;

[0155] applying a belt cord layer to the carcass ply or plies and optionally at least partially to the first and / or second sidewall layer (preferably covering the axially inner ends of the first and / or second sidewall layer);

[0156] applying a covering layer covering the belt cord layer;

[0157] A tread is applied, optionally so as to cover at least a portion of the first sidewall layer.

[0158] In another embodiment, the first sidewall layer is applied together with the second sidewall layer in / as a single tire component.

[0159] In yet another embodiment, the tire assembly further comprises a chafer of the pair of chafers. Thus, the chafer, the first sidewall layer and the second sidewall layer are applied to one or more carcass plies in the form of a tire assembly. As mentioned above, such a tire assembly can be an extruded tire assembly. For example, the extrusion can be performed with a multiple extruder, such as a triple extruder in the case of extruding two sidewall layers and a chafer, or a quadruple extruder in the case of extruding two sidewall layers, a chafer and a shoulder pad.

[0160] In yet another embodiment, the tire assembly further comprises a shoulder wedge. If the tire assembly comprises a shoulder wedge, the belt cord layer is preferably also attached to the shoulder wedge, so that the axially outer end of the radially innermost belt cord layer covers the shoulder wedge, and / or preferably also covers the axially inner end of the first and / or second sidewall layer.

[0161] Figure 1 A schematic cross section of a tire 1 according to a preferred embodiment of the present invention is shown. The tire 1 comprises a tread 10, a pair of beads 11, a pair of bead apex rubber cores 1.3, a pair of bead chafers 9 and a pair of sidewalls, wherein each sidewall comprises a first sidewall layer 2 and a second sidewall layer 20. In addition, the tire 1 comprises two carcass plies 3, 4, two belt cord layers 6, 7 and a covering layer 8. Facing the tire cavity, the tire has an inner liner 17. The second sidewall layer 20 is arranged between the adjacent carcass plies and the first sidewall layer 2 on the axial outside. Thus, each sidewall of the pair of sidewalls has a double sidewall layer construction. Such a construction can help improve various properties of the tire 1. For example, the combination of the first sidewall layer 2 and the second sidewall layer 20 can improve the robustness of the tire 1. Alternatively, the adhesion can be improved by the second sidewall layer (particularly during the tire construction or assembly process). The tire can also have additional sidewall layers (for example, three sidewall layers, not shown in this article). However, only two sidewall layers 2, 20 as shown in this embodiment are preferred.

[0162] The first side wall layer 2 has a greater radial height (or length) h than the second side wall layer 20. rf The second sidewall layer has a radial height (or length) h rs In addition, the first sidewall layer 2 extends with its radial inner end toward the radial inner position, covering the total radial height (or length) h of the bead chafer 9. rc is larger than the radially upper half. The radially inner end of the second sidewall layer 20 extends to the radially outer end of the bead filler 9 and is preferably in contact with the bead filler 9. In the crown region of the tire, the radially outer end of the second sidewall layer 20 extends to a position between the radially outer carcass ply 4 and the radially innermost belt cord layer 6. Similarly, the first sidewall layer 20 has a radially outer end that terminates between the radially outer carcass ply 4 and the radially innermost belt cord layer 6. However, the second sidewall layer 20 extends further toward the equatorial plane EP of the tire 1, thereby terminating at an axial position closer to the equatorial plane EP of the tire than the end of the radially outer end of the first sidewall layer 2.

[0163] For further understanding, Figure 1, a radial direction r, an axial direction a and a circumferential direction c are shown. The axial direction a is parallel to the axis of rotation of the tire 1. The radial direction r is perpendicular to said axis (and to the axial direction a) of the tire 1. It is also parallel to the equatorial plane EP of the tire 1. The circumferential direction c is perpendicular to the axial direction a and to the radial direction r. It is emphasized that these directions are not limited to a specific orientation unless otherwise indicated in this text.

[0164] In one non-limiting embodiment, the first sidewall layer 2 is composed of a first rubber composition, for example, having high puncture resistance and / or cut resistance. For example, the rubber composition of the first sidewall layer may preferably include 40 to 60 phr of polybutadiene rubber; 60 to 40 phr of natural rubber and one or more of synthetic polyisoprene; 10 to 40 phr of carbon black; 20 to 60 phr of silica; and 0 to 8 phr of oil. In particular, a combination of isoprene rubber, polybutadiene rubber, and a blend of carbon black and silica can help provide improved cut resistance and / or abrasion resistance.

[0165] In a specific example of the first rubber composition, the first rubber composition includes 50 phr of polybutadiene, 50 phr of natural rubber, 30 phr of carbon black, 30 phr of silica, 4 phr of oil, 3 phr of phenolic resin, 1.5 phr of wax, about 3 phr of silane, about 5 phr of antidegradant (including phenylenediamines), 2 phr of zinc oxide, 1.5 phr of sulfur, and 1.5 phr of accelerator.

[0166] In a non-limiting embodiment, the second sidewall layer is composed of a second rubber composition, which includes 40phr to 75phr of polybutadiene rubber; 60phr to 25phr of natural rubber and one or more of synthetic polyisoprene; 30phr to 60phr of carbon black; 0phr to 5phr of silica; and 10phr to 25phr of oil. The second rubber composition, for example, has only a very limited amount of silica or even no amount of silica. In addition, it has more oil than the first rubber composition. The benefits of the second rubber composition are, for example, better adhesion to, for example, adjacent carcass plies during tire construction compared to the first rubber composition, and / or higher crack growth resistance.

[0167] In one specific example, the second rubber composition includes 65 phr of polybutadiene rubber, 35 phr of natural rubber, about 50 phr of carbon black, about 15 phr of oil, about 3.5 phr of phenolic resin, about 1 phr of wax, about 5 phr of antidegradant (including phenylenediamines), 1 phr of stearic acid, 2 phr of zinc oxide, about 0.6 phr of accelerator, and about 1 phr of sulfur.

[0168] The inventors have tested the above-mentioned specific first and second rubber compositions with respect to their wear properties. The first rubber composition has a 66 mm 3 The relative volume loss of the second rubber composition is 95 mm 3 (where lower is better, ie less volume loss.) Thus, providing the sidewall with the first rubber composition in the first (outer layer) significantly improves the cut resistance and / or robustness of the tyre 1 .

[0169] Another test conducted by the inventors on two specific examples of the first and second rubber compositions determined the crack growth rate of each of these rubber compositions. The crack growth rate of the second rubber composition was about 0.004 mm / min, while for the first rubber composition, the same test result was restored to about 0.012 mm / min. In this case, the lower value is considered to be better. In other words, although the first rubber composition is more resistant to cutting and / or puncture, the second rubber composition is more robust in terms of crack growth. By combining these two layers in the sidewall, these two properties, i.e., good cut resistance and limited crack growth, can be obtained together at the same time.

[0170] In this example, the first sidewall layer 2 has a lower viscosity than the second sidewall layer 20. Reasons may include a higher silica content in the outer first sidewall layer 2 and / or a lower oil content in the first sidewall layer 2 compared to the second sidewall layer 20. Thus, using only the first rubber composition in a single-layer sidewall will have limited viscosity and may impair the construction process of such tires, especially in the case of high section height tires (e.g., greater than 225 mm) and / or thick sidewall components (e.g., greater than 3.5 mm). In particular, this is especially true for some off-road tires.

[0171] Figure 2 Another preferred embodiment of a tire 1' is shown, comprising a tread 10', in this case three carcass plies 3', 4', 5' (instead of Figure 1 The tire 1 has only two carcass plies, two belt cord layers 6', 7', a covering layer 8', an inner liner 17', a pair of beads 11', a tire apex 13', a bead filler 9', a first sidewall layer 2' and a second sidewall layer 20'. The first sidewall layer 2' has a radial height h rf 'extends upward, and the second sidewall layer 20' is at a radial height h rs 'Extended. The bead chafer 9' is at a radial height h rc The equatorial plane EP of the tire 1' and the axial direction a, radial direction r and circumferential direction c are Figure 1 Similarly expressed.

[0172] Figure 1 and 2 The main difference between the embodiments of the present invention is that the tire 1' has a three-layer carcass and a radially larger bead filler 9'. The rubber composition suitable for the first sidewall layer 2' and the second sidewall layer 20' is preferably the same as that for Figure 1 The same or similar to those mentioned in the first embodiment.

[0173] The chafer rubber composition (which may be described herein as a third rubber composition) may, for example, include 10 to 50 phr of polybutadiene rubber, 10 to 40 phr of one or more of natural rubber and synthetic polyisoprene, 10 to 40 phr of styrene butadiene rubber, 70 to 100 phr of filler, for example including a major portion of carbon black, such as 70 to 90 phr of carbon black, and 10 to 20 phr of oil.

[0174] The present invention and / or one or more embodiments thereof help to provide a robust tire, particularly for off-road applications. Such tires have advanced carcass and / or sidewall constructions. The proposed sidewall design can be efficiently constructed.

[0175] The embodiments and / or features described above, including those of the first and second aspects of the invention, may be combined with each other.

[0176] The present invention may be modified according to the description provided herein. Although certain representative embodiments and details have been shown for the purpose of illustrating the present invention, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the present invention. Therefore, it should be understood that changes may be made in the specific embodiments described, and these changes will be within the full intended scope of the present invention as defined by the appended claims.

Claims

1. A tire comprising a tread, at least one carcass ply, a pair of bead portions, and a pair of sidewalls, wherein each sidewall of the pair of sidewalls extends between the tread and a corresponding bead portion of the pair of bead portions, wherein at least one of the pair of side walls comprises: a first circumferential sidewall layer, and A second circumferential sidewall layer extends axially inwardly of the first sidewall layer between the first sidewall layer and an adjacent carcass ply.

2. The tire of claim 1, wherein the second sidewall layer extends over a radial height in the range of 50% to 90% of the total radial height of the first sidewall layer.

3. The tire of claim 1, wherein the tire further comprises at least one pair of chafers including a first chafer in contact with one or more of the first sidewall layer and the second sidewall layer. 4 . The tire of claim 3 , wherein the first sidewall layer at least partially covers the first chafer on an axially outer side of the first chafer. 5 . The tire of claim 4 , wherein the second sidewall layer contacts the first chafer at a radially outer end portion of the first chafer. 6 . The tire of claim 5 , wherein the second sidewall layer overlaps the first chafer by at most 5% of the total radial height of the first chafer.

7. The tire of claim 1 , wherein the second sidewall layer has a thickness along at least 90% of its extension from its radially outer end to its radially inner end of one or more of: i) 50% to 300% of the thickness of the adjacent carcass ply; and ii) 0.5 mm to 5 mm.

8. The tire of claim 1, wherein the first sidewall layer extends further toward a radially innermost position of the tire than the second sidewall layer.

9. The tire of claim 1, wherein the radially innermost end of the first sidewall layer extends to a radial position so as to cover at least 50% of a total radial height of an adjacent chafer of the tire.

10. The tire of claim 1, wherein the radially outermost ends of the first sidewall layer and the second sidewall layer are disposed between a radially innermost belt layer and a carcass ply of the tire.

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