Tread bands for pneumatic tires and tires containing them

Abstract

A tread band for a pneumatic tire and a tire including the same, the tread band having transverse sipes and including a first hydrocarbon polymer resin additive and a second hydrocarbon polymer resin additive.

Description

[Technical Field]

[0001] The present invention relates to a tread band for a pneumatic tire and a tire comprising the same, wherein the tread band comprises a first hydrocarbon polymer resin additive and a second hydrocarbon polymer resin additive, which, in combination with the presence of transverse sipes in the tread band, have a beneficial and / or synergistic effect on the wet performance, rolling resistance, and wear resistance of the tire comprising the tread band. [Background technology]

[0002] To reduce CO2 emissions, there is a demand for vehicles with lower fuel consumption, which can be achieved by reducing the rolling resistance of the vehicle's tires. It is also important that the tires have good grip performance, especially on wet surfaces (i.e., wet performance). High wear resistance is also a crucial factor for a tire's long service life. Wet performance ("WET"), rolling resistance ("RR"), and wear resistance ("WEAR") together are known as the "magic triangle" of viscoelastic properties. There is an ongoing need to manufacture tires with an improved balance between these properties.

[0003] The chemical composition of a tire can be modified to adjust its dynamic / mechanical properties. In attempts to achieve a better WET / RR / WEAR balance, the use of modified rubber, a mixture of rubber and various reinforcing fillers, has been proposed. However, improving any one of these properties of a tire often negatively affects at least one of the others. For example, it is difficult to improve the wet performance of a tire without negatively impacting its rolling resistance and wear resistance. Similarly, increasing the amount of reinforcing filler leads to improved wear performance, which in turn reduces rolling resistance.

[0004] Hydrocarbon resins are widely used as processing aids to modify the viscoelastic properties of rubber compositions and thus improve tire tread performance characteristics, such as wet grip and rolling resistance. A wide range of hydrocarbon resins are known for use in the manufacture of rubber compositions for tire treads, including aliphatic resins, aromatic resins, partially hydrogenated resins, and fully hydrogenated resins. Combinations of different hydrocarbon resins have been proposed. For example, U.S. Patent Application Publication No. 2019 / 0092937 proposes a blend of a C5 aliphatic resin with a dicyclopentadiene DCPD resin or an aromatic pure monomer resin to adjust the material properties of an immiscible blend of natural rubber and high cis polybutadiene rubber.

[0005] The physical morphology of the tire tread, particularly the size and shape of the portion that contacts the road surface (contact patch), also affects its performance. Generally, tire treads are cut to form tread elements. Circumferential grooves in the tread can improve drainage (and thus affect wet performance), while lateral grooves can improve traction and wear resistance. Sipes are small grooves cut laterally across larger tread elements and are known to improve traction in wet conditions and reduce wear. There remains a need in the art for tire treads where chemical composition and physical morphology are optimized in parallel to improve tire performance.

[0006] The present invention aims to satisfy unmet requirements in the art and to solve problems related to existing tires. [Overview of the project]

[0007] The present invention is based on the discovery that optimizing the chemical composition and physical morphology of a tread band can have beneficial and / or synergistic effects on the properties of a tire prepared from the tread band. Accordingly, the present invention provides a tread band comprising a first hydrocarbon polymer resin and a second hydrocarbon polymer resin and having transverse sipes, which together improve tire performance compared to a tire prepared without the sipes of the present invention or without the hydrocarbon polymer resins of the present invention.

[0008] In a first aspect, the present invention relates to a tread band for a tire suitable for engaging with the road surface in a footprint area, Two shoulder regions at the axial outer end of the tread band, A central region is identified between the shoulder regions, A row of shoulder elements arranged along the first circumferential rib in each of the shoulder regions, At least two rows of central elements arranged along the second circumferential rib in the central region, It comprises at least three circumferential grooves that separate a first circumferential rib and a second circumferential rib from other circumferential ribs, The central element is separated along its entire axial width by transverse sipes, which define two endpoints at their respective axial outer ends where they intersect with the circumferential grooves. The treadbands are (i) A first hydrocarbon polymer additive which is a partially hydrogenated C5 resin, (ii) A tread band further comprising a second hydrocarbon polymer additive which is a fully hydrogenated resin selected from the group consisting of hydrogenated C5 resin, hydrogenated C5 / C9 copolymer resin, hydrogenated C9 resin, and combinations thereof.

[0009] Viewed in a second aspect, the present invention is a pneumatic tire comprising a tread band according to the first aspect.

[0010] Further advantageous features of the present invention are described herein.

Brief Description of the Drawings

[0011] [Figure 1] It is a perspective view of a tire according to a preferred embodiment of the present invention. [Figure 2] It is a front view of the tire of FIG. 1. [Figure 3] It is a partial front view of the tire of FIG. 1. [Figure 4] It is a schematic view of a transverse sipe forming portion of a mold for the tire of FIG. 1. [Figure 5] It is a schematic view of a first alternative sipe forming mold for forming a first alternative transverse sipe having a protrusion in a central region of a sipe base, the protrusion being rounded at its base and upper edge and protruding partially upward from the sipe base. [Figure 6] It is a schematic view of a second alternative sipe forming mold for forming a second alternative transverse sipe having a series of raised ellipses arranged linearly along the length of the sipe. [Figure 7] It is a schematic view of a third alternative sipe forming mold for forming a third alternative transverse sipe having a longitudinal sine wave feature at the base of the sipe.

Modes for Carrying Out the Invention

[0012] The present invention is a tread band for a tire suitable for engaging a road surface in a footprint region, two shoulder region areas at the axially outer ends of the tread band, a central region identified between the shoulder region areas, a row of shoulder elements arranged along a first circumferential rib in each of the shoulder region areas, at least two rows of central elements arranged along a second circumferential rib in the central region, and at least three circumferential grooves separating the first circumferential rib and the second circumferential rib from another circumferential rib. The central element is separated along its entire axial width by transverse sipes, which define two endpoints at their respective axial outer ends where they intersect with the circumferential grooves. The treadbands are (i) A first hydrocarbon polymer additive which is a partially hydrogenated C5 resin, (ii) A tread band is provided comprising a second hydrocarbon polymer additive, which is a fully hydrogenated resin selected from the group consisting of hydrogenated C5 resin, hydrogenated C5 / C9 copolymer resin, hydrogenated C9 resin, and combinations thereof.

[0013] The inventors have discovered that combining the physical properties of a tread band with a hydrocarbon polymer additive provides improved wet performance ("WET"), rolling resistance ("RR"), and wear resistance ("WEAR"), as well as a better balance between these properties, compared to tread bands having different physical properties and / or not containing a hydrocarbon polymer additive. The beneficial effect of combining the physical properties of a tread band with a hydrocarbon polymer additive may be a synergistic effect.

[0014] Hydrocarbon polymer additive components The tread bands described herein include a hydrocarbon polymer additive component and may be formed or prepared from a composition containing a hydrocarbon polymer additive component. As used herein, the term “hydrocarbon polymer additive” refers to a hydrocarbon resin and is used herein interchangeably with the term “hydrocarbon resin.” The hydrocarbon polymer additive component includes a first hydrocarbon polymer additive which is a partially hydrogenated C5 resin, and a second hydrocarbon polymer additive which is a fully hydrogenated resin selected from a hydrogenated C5 resin, a hydrogenated C5 / C9 copolymer resin, a hydrogenated C9 resin, and combinations thereof. Additional resins may be present, but in one embodiment, the only resins present are the first hydrocarbon resin and the second hydrocarbon resin described herein. Exemplary combinations of the first and second hydrocarbon polymer additives include a partially hydrogenated C5 resin and a fully hydrogenated C5 resin, a partially hydrogenated C5 resin and a fully hydrogenated C5 / C9 copolymer resin, and a partially hydrogenated C5 resin and a fully hydrogenated C9 resin. A preferred combination of hydrocarbon polymer additives for use in the present invention is a partially hydrogenated C5 resin and a fully hydrogenated C9 resin.

[0015] As used herein, the term “hydrogenated resin” refers to a resin obtained by subjecting a resin to reductive hydrogenation. Hydrogenation may be partial, thus producing a “partially hydrogenated resin,” or it may be substantially complete, thereby producing a “fully hydrogenated” resin.

[0016] As used herein, the term “partially hydrogenated” means that the resin component contains less than 100% olefin protons, and this 1This can be determined by 1H NMR spectroscopy. Partially hydrogenated resins are well known in the art and can have different degrees of hydrogenation. In some embodiments, a partially hydrogenated resin may contain less than 95% olefin protons, more preferably less than 90% olefin protons. In some embodiments, it may contain less than 75% olefin protons, for example less than 50% olefin protons. In some embodiments, a partially hydrogenated resin may contain less than 40% olefin protons, less than 25% olefin protons, less than 15% olefin protons, or less than 10% olefin protons. For example, it may contain less than 9%, less than 8%, less than 7%, or less than 6% olefin protons. In one embodiment, a partially hydrogenated resin may contain about 5% or more olefin protons. For example, it may contain 5% to 90% olefin protons. In one embodiment, a partially hydrogenated resin may contain about 5% olefin protons, i.e., it is about 95% hydrogenated.

[0017] As used herein, the term “fully hydrogenated” means that the resin component contains less than 5% olefin protons. In some embodiments, a fully hydrogenated resin may contain less than 4%, preferably less than 3%, more preferably less than 2%, for example less than 1%, less than 0.5%, or less than 0.1%, for example less than 0.05% olefin protons.

[0018] In one embodiment, the fully hydrogenated resin may contain 0% to about 3% olefin protons, i.e., it is about 97% to 100% hydrogenated. In one embodiment, the fully hydrogenated resin may contain 0% to about 2% olefin protons, i.e., it is about 98% to 100% hydrogenated. In one embodiment, the fully hydrogenated resin may contain 0% to about 1% olefin protons, i.e., it is about 99% to 100% hydrogenated. In one embodiment, it may contain about 0% olefin protons.

[0019] Hydrogenated resins include resins produced by the reductive hydrogenation of resins containing aromatic components. As to be understood, any reference to olefin protons in this specification is intended to include any protons that may be present as part of an aromatic ring system. Percentages listed herein with respect to olefin proton content and degree of hydrogenation refer to mole percent.

[0020] For any selected combination of hydrocarbon resins used in the present invention, the degree of hydrogenation of the "fully hydrogenated" resin is greater than that of the "partially hydrogenated" resin, i.e., the "fully hydrogenated" resin has a lower olefin proton content than the "partially hydrogenated" resin. Advantageously, the difference in the degree of hydrogenation of the different hydrocarbon resins for use in the present invention may be small. For example, the mol% of the olefin proton content of the different resins may differ by less than 10 mol%, e.g., less than 8 mol%, less than 7 mol%, less than 6 mol%, less than 5 mol%, less than 4 mol%, or less than 3 mol%. In one embodiment, it may differ by 1 mol% to 10 mol%, e.g., 1 mol% to 5 mol%.

[0021] The first hydrocarbon polymer additive is a partially hydrogenated C5 resin. As used herein, the term “C5 resin” refers to a resin obtained by polymerization of a decomposed naphtha feed containing C5 monomers. The C5 monomers include olefins, linear conjugated diolefins, and cyclic conjugated diolefins. Other monomers may be further present in the feed, including, but not limited to, dicyclopentadiene (DCPD).

[0022] In one embodiment, the C5 resin for use in the present invention can be obtained by copolymerization of a C5 monomer with a dicyclopentadiene (DCPD) monomer. If DCPD monomers are present, they are generally provided in small amounts. For example, the DCPD content in the feed used to produce the resin may be less than about 5% by weight, for example, less than about 2% by weight. Preferably, the C5 resin may contain monomer units derived from the C5 monomer and DCPD. Thus, a partially hydrogenated C5 resin may contain a copolymer of partially hydrogenated C5 and dicyclopentadiene DCPD, preferably with DCPD present in an amount of less than 5% by weight of the C5 and DCPD monomers. However, in another embodiment, the feed used to provide the C5 resin may be free of any DCPD monomers. These monomers can be removed from the feed stream by methods generally known in the art. Thus, in one embodiment, the C5 resin may essentially consist of monomer units derived from the C5 monomer.

[0023] To improve wet performance, the hydrogenated C5 resin used in the present invention has a high softening point, for example, a softening point higher than 110°C. As used herein, the term "softening point" refers to the temperature at which the resin flows. The softening point of the resin can be measured by the ring-ball method. Unless otherwise specified, the softening points listed herein are "ring-ball softening points," i.e., the temperature at which the sphere descends in a measurement of the softening point using a ring-ball softening point measuring device in accordance with ASTM D 3461-76. In certain embodiments, the softening point of the hydrogenated C5 resin is 110°C or higher, 115°C or higher, preferably 118°C or higher, more preferably 121°C or higher, for example 123°C or higher. For example, it may be 125°C or higher. From the viewpoint of suppressing the rise in tanδ at 0°C, the softening point of the hydrogenated C5 resin is preferably 145°C or lower. For example, the softening point may be 143°C or lower, 140°C or lower, 136°C or lower, or 135°C or lower. For example, the softening point of the hydrogenated C5 resin may be 115°C to 145°C, more preferably 120°C to 140°C, more preferably 125°C to 135°C, for example, 125, 126, 127, 128, 129, 230, 131, 132, 133, 134, or 135°C.

[0024] From the viewpoint of resin miscibility, the weight-average molecular weight of partially hydrogenated C5 resins is generally in the range of 200 g / mol to 2000 g / mol. Unless otherwise specified, references to molecular weight in this specification refer to the weight-average molecular weight Mw. The weight-average molecular weight is determined by gel permeation chromatography (GPC) against a polystyrene standard. In some embodiments, the weight-average molecular weight of the partially hydrogenated C5 resin may be 300 g / mol or more, preferably 600 g / mol or more, and more preferably 800 g / mol or more. In other embodiments, the weight-average molecular weight of the partially hydrogenated C5 resin may be 2000 g / mol or less, preferably 1800 g / mol or less, more preferably 1600 mol / g or less, and even more preferably 1400 g / mol or less. For example, the weight-average molecular weight of a partially hydrogenated C5 resin may be 600 g / mol to 1600 g / mol, more preferably 800 g / mol to 1400 g / mol, more preferably 1000 g / mol to 1200 g / mol, for example 1000, 1100, or 1200 g / mol.

[0025] Glass transition temperature (T) of partially hydrogenated C5 resin g The temperature may be 50°C or higher, preferably 60°C to 90°C, more preferably 65°C to 85°C. g The values ​​are determined using differential scanning calorimetry (DSC) with a starting temperature of -140°C and a temperature gradient of 15°C / min. Unless otherwise specified, all test methods described herein are performed at 23°C and 50% relative humidity.

[0026] The partially hydrogenated C5 resin used in the present invention is a resin produced by subjecting the C5 resin described herein to partial reductive hydrogenation. Examples of C5 resins include aliphatic petroleum resins obtained by (co)polymerizing the C5 fraction obtained by the thermal decomposition of naphtha in the petrochemical industry. The C5 fraction typically contains olefinic hydrocarbons such as 1-pentene, 2-pentene, 2-methyl-1-butene, 2-methyl-2-butene, and 3-methyl-1-butene, and diolefinic hydrocarbons such as 2-methyl-1,3-butadiene, 1,2-pentadiene, 1,3-pentadiene, and 3-methyl-1,2-butadiene. As described herein, the C5 fraction may further contain other monomers such as dicyclopentadiene (DCPD). If DCPD is present, it is generally in small amounts, for example, less than 5% by weight of the C5-containing fraction, for example less than 2% by weight. By subjecting any of these resins to partial reduction and hydrogenation, a partially hydrogenated C5 resin can be produced, for example, one containing 3% to 9% olefin protons, preferably 4% to 8% olefin protons, and more preferably 4% to 6% olefin protons. In one embodiment, the partially hydrogenated C5 resin contains about 5% olefin protons. Commercially available products can be used as the partially hydrogenated C5 resin.

[0027] In a preferred embodiment, the partially hydrogenated C5 resin has the following characteristics, namely: Olefin proton content of less than 10 mol%, preferably 2 mol% to 8 mol%, A softening point of 110°C or higher, preferably 120°C to 140°C. The weight-average molecular weight may be one or more of 200 g / mol to 2000 g / mol, preferably 800 g / mol to 1400 g / mol. In this embodiment, the partially hydrogenated C5 resin has a glass transition temperature (T) of 50°C or higher, preferably 60°C to 90°C. g ) may have, and / or, The partially hydrogenated C5 resin may also contain a copolymer of partially hydrogenated C5 and dicyclopentadiene DCPD, preferably with DCPD present in an amount of less than 5% by weight of the C5 and DCPD monomers.

[0028] The second hydrocarbon polymer additive is selected from fully hydrogenated C5 resins, fully hydrogenated C5 / C9 copolymer resins, fully hydrogenated C9 resins, and combinations thereof. In a preferred embodiment, the second hydrocarbon polymer additive is a fully hydrogenated C9 resin.

[0029] To improve wet performance, the second hydrocarbon resin used in the present invention has a high softening point, for example, a softening point higher than 100°C. In certain embodiments, the softening point of the second hydrocarbon resin is 110°C or higher, preferably 115°C or higher, and preferably 118°C or higher. From the viewpoint of suppressing the rise in tanδ at 0°C, the softening point of the second hydrocarbon resin is preferably 145°C or lower. For example, the softening point may be 143°C or lower, 140°C or lower, 136°C or lower, 135°C or lower, 133°C or lower, or 130°C or lower. For example, the softening point of the second hydrocarbon resin may be 100°C to 145°C, preferably 110°C to 135°C, more preferably 115°C to 130°C, for example, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, or 130°C.

[0030] From the viewpoint of resin miscibility, the weight-average molecular weight of the second hydrocarbon resin is generally in the range of 700 g / mol to 1500 g / mol. In some embodiments, the weight-average molecular weight of the second resin may be 800 g / mol or more, preferably 900 g / mol or more, and more preferably 1000 g / mol or more. In other embodiments, the weight-average molecular weight of the second hydrocarbon resin may be 1400 g / mol or less, preferably 1300 g / mol or less, and more preferably 1200 mol / g or less. In one embodiment, the second hydrocarbon resin has a softening point higher than 100°C and a weight-average molecular weight of 700 g / mol to 1500 g / mol. More preferably, the second hydrocarbon resin is a fully hydrogenated C9 resin having a softening point higher than 100°C and a weight-average molecular weight of 700 g / mol to 1500 g / mol. The second hydrocarbon resin is produced by subjecting the resin to substantially complete (e.g., complete) reductive hydrogenation.

[0031] Glass transition temperature of hydrogenated C9 resin (T g The temperature may be 50°C or higher, preferably 55°C to 85°C, and more preferably 60°C to 80°C.

[0032] The resin used as the starting material is selected from C5 resins, C5 / C9 resins, C9 resins, and combinations thereof. An example of a C5 resin that can be used to produce a fully hydrogenated C5 resin is an aliphatic petroleum resin obtained by (co)polymerizing the C5 fraction obtained by the thermal decomposition of naphtha in the petrochemical industry. The C5 fraction typically contains olefinic hydrocarbons such as 1-pentene, 2-pentene, 2-methyl-1-butene, 2-methyl-2-butene, and 3-methyl-1-butene, and diolefinic hydrocarbons such as 2-methyl-1,3-butadiene, 1,2-pentadiene, 1,3-pentadiene, and 3-methyl-1,2-butadiene. It may also contain other monomers, such as DCPD. Commercially available C5 resins can be used.

[0033] The term "C5 / C9 resin" refers to C5-C9 synthetic petroleum resins, such as petroleum-derived C5-C9 resins containing AlCl3. 11 Examples include solid polymers obtained by polymerization using fractions, Friedel-Crafts type catalysts such as BF3, and more specifically, copolymers containing styrene, vinyltoluene, α-methylstyrene, indene, etc. as main components. As for the C5 / C9 resin, a resin with a small amount of C9 or higher components is preferred from the viewpoint of compatibility with rubber components. For example, the amount of C9 or higher components may be less than 50% by weight, preferably less than 40% by weight, based on the total amount of resin.

[0034] Commercially available C5 / C9 resins can be used.

[0035] The term "C9 resin" refers to C9 synthetic petroleum resins, including polymers obtained by polymerization using Friedel-Crafts type catalysts such as AlCl3 and BF3. Examples of C9 resins include copolymers containing indene, styrene, α-methylstyrene, vinyltoluene, etc., as main components.

[0036] The olefin proton content of the first hydrocarbon polymer additive and the second hydrocarbon polymer additive may differ by less than 10 mol%. The second hydrocarbon polymer additive may contain 0 mol% to about 3 mol% of olefin protons, for example, 0 mol% of olefin protons. The second hydrocarbon polymer additive may have a weight-average molecular weight of about 700 g / mol to about 1500 g / mol and / or a softening point above 100°C.

[0037] In a preferred embodiment, the hydrogenated C9 resin has the following characteristics, namely, Softening point is 100°C or higher, preferably 110°C to 135°C. Weight-average molecular weight (Mw) of 700 g / mol to 1500 g / mol, and / or, Glass transition temperature (T) of at least 50°C, preferably 60°C to 80°C g ), may have one or more of the following.

[0038] In a preferred embodiment, the tread band comprises a first hydrocarbon polymer additive which is a partially hydrogenated C5 resin and a second hydrocarbon polymer additive which is a fully hydrogenated C9 resin, each having the characteristics of the preferred embodiments of the partially hydrogenated C5 resin and the fully hydrogenated C9 resin described above.

[0039] To improve the dispersion of components, the tread band may contain a first hydrocarbon polymer additive in an amount of 1 phr to 30 phr, preferably 5 phr to 10 phr, for example 5, 6, 7, 8, 9, or 10 phr. The tread band may also contain a second hydrocarbon polymer additive in an amount of 1 phr to 30 phr, preferably 5 phr to 10 phr, for example 5, 6, 7, 8, 9, or 10 phr. The tread band may contain the first and second hydrocarbon polymer additives in a total amount of 2 phr to 60 phr, more preferably 10 phr to 20 phr, for example 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 phr. Unless otherwise specified, the term "phr" means parts (by weight) per 100 parts of rubber. This is a term commonly used in the art, where the components of a composition are measured relative to the sum of all rubber (i.e., elastomer) components. The sum of the rubber components is defined as 100 phr, and all other components are defined as a ratio to 100 parts of rubber and expressed as "phr". The ratio of the amount of the first hydrocarbon polymer additive to the amount of the second hydrocarbon polymer additive may be 10:1 to 1:10, preferably 5:1 to 1:5, more preferably 2:1 to 1:2, and more preferably 1:1.

[0040] To further improve the dispersion of components and thus the performance of the tire, the tread band may also contain a first hydrocarbon polymer additive, which is a partially hydrogenated C5 resin having the characteristics of a preferred embodiment of the partially hydrogenated C5 resin described herein, in an amount of 6 phr to 10 phr, and a second hydrocarbon polymer additive, which is a fully hydrogenated C9 resin having the characteristics of a preferred embodiment of the hydrogenated C9 resin described herein, in an amount of 6 phr to 10 phr, wherein the ratio of the amount of the first hydrocarbon polymer additive to the amount of the second hydrocarbon polymer additive is 1:1.

[0041] Elastomer component The tread band of the present invention may contain one or more elastomer components. The tread band may also be formed from, prepared from, or prepared using a rubber composition containing one or more elastomer components. The rubber composition may be a vulcanizable rubber composition, which may be vulcanized.

[0042] Styrene-butadiene rubber (SBR) is commonly used in the tire industry and can be produced by well-known methods, for example, by copolymerization of the corresponding monomers in an emulsion, suspension, or solution. In one embodiment, the styrene-butadiene copolymer for use in the present invention may be solution-polymerized styrene-butadiene rubber (SSBR) or emulsion-polymerized styrene-butadiene rubber (ESBR). "Emulsion-polymerized styrene-butadiene rubber" means that styrene and 1,3-butadiene are copolymerized in an aqueous emulsion. Such methods are well known and understood by those skilled in the art.

[0043] In the present invention, the tread band comprises and / or can be prepared from a first elastomer component comprising one or more styrene-butadiene copolymers. Preferably, the first elastomer component may comprise a first styrene-butadiene copolymer and a second styrene-butadiene copolymer.

[0044] In some embodiments, the styrene content of the first SBR copolymer may be 10% to 40% by weight (by weight of the first SBR copolymer), preferably 10% to 30% by weight, more preferably 15% to 25% by weight, and even more preferably 21% to 24% by weight, for example, about 21% by weight. The styrene content is 1 This can be determined by 1H-NMR.

[0045] The first styrene-butadiene copolymer may preferably be an end-functionalized copolymer that has an interactive and / or synergistic effect on the properties of the tread band, resulting in favorable properties. Specifically, the interaction between the end-functionalized styrene-butadiene copolymer and silica, which may be synergistic in the presence of a silica filler system, can result in improved dispersion of the filler system in the rubber composition and the products made therefrom. "End-functionalized" SBRs are sometimes called "end-modified" SBRs. In some embodiments, the styrene-butadiene copolymer may be an end-functionalized SSBR. Preferably, the first styrene-butadiene copolymer is functionalized with end-carboxyl groups. The end-functionalized SSBR copolymer was prepared according to Example 3 of International Patent Application 2014 / 173706 A1, as described below.

[0046] To an inactivated 20-liter reactor, hexane (8.5 kg), 1,3-butadiene (1185 g), styrene (315 g), 2,2-bis(2-tetrahydrofuryl)propane (8.6 mmol), and butyllithium (11.3 mmol) were added, and the contents were heated to 60°C. Polymerization was carried out at 60°C for 25 minutes with stirring. Subsequently, an equimolar amount of hexamethylcyclotrisiloxane (as a solution in cyclohexane) was added to the amount of butyllithium, and the reactor contents were then heated to 60°C for a further 20 minutes to cap the anionic ends of the polymer chains. Twenty minutes after the addition of hexamethylcyclotrisiloxane, an equimolar amount of 2,2-dimethyl-1-oxa-4-thia-2-silacyclohexane-6-one (as a solution in toluene) was added to the amount of butyllithium and hexamethylcyclotrisiloxane, and the mixture was heated to 60°C for a further 20 minutes. The rubber solution was drained, stabilized with Irganox® 1520 (2,4-bis(octyllithiomethyl)-6-methylphenol) (3g), and the solvent was removed by stripping with water vapor. The rubber crumbs were dried under reduced pressure at 65°C.

[0047] The first styrene-butadiene copolymer may have a vinyl content of 50% to 75% by weight, preferably 58% to 68% by weight, for example, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, or 68% by weight.

[0048] The first styrene-butadiene copolymer may have a glass transition temperature Tg in the range of -40°C to -15°C, preferably -30°C to -20°C, for example, -30, -29, -28, -27, -26, -25, -24, -23, -22, -21, -20°C.

[0049] The first styrene-butadiene copolymer may have an oil content of 0.5 to 10 parts per 100 parts of the first styrene-butadiene copolymer, for example, 5 parts per 100 parts of the first styrene-butadiene copolymer.

[0050] The tread band contains a first styrene-butadiene copolymer in an amount of at least 30 phr, more preferably 40 phr to 70 phr, more preferably 50 phr to 65 phr, for example 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, or 65 phr.

[0051] The second styrene-butadiene copolymer may have a styrene content of 25% to 50% by weight, preferably 32% to 42% by weight, for example, 33, 34, 35, 36, 37, 38, 39, 40, 41, or 42% by weight of the second SBR copolymer.

[0052] The second styrene-butadiene copolymer may have a vinyl content of 45% to 70% by weight, preferably 52% to 62% by weight, for example, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, or 62% by weight.

[0053] The second styrene-butadiene copolymer may be oil-fed, and therefore may have an oil content of 10 to 35 parts, preferably 20 to 30 parts, per 100 parts of the second styrene-butadiene copolymer.

[0054] The second styrene-butadiene copolymer may have a glass transition temperature Tg in the range of -40°C to -10°C, preferably -25°C to -15°C, for example, -25, -24, -23, -22, -21, -20, -19, -18, -17, -16, -15°C.

[0055] The tread band may also contain a second styrene-butadiene copolymer in an amount of at least 10 phr, more preferably 15 to 35 phr, more preferably 20 to 30 phr, for example 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 phr.

[0056] The tread band may further contain a second elastomer component, which includes natural rubber. Natural rubber is well known to be used in the manufacture of tires. The natural rubber used in this invention is not particularly limited and may be any natural rubber or combination of natural rubbers commonly used in the tire industry. Specific examples include standard Malaysian rubber (SMR), standard Indonesian rubber (SIR), specific Singaporean rubber (SSR), standard Lanka rubber (SLR), Thai test rubber (TTR), and Nigerian standard rubber (NSR).

[0057] The tread band may contain natural rubber in an amount of at least 5 phr, more preferably 10 to 30 phr, more preferably 15 to 25 phr, for example 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 phr.

[0058] Other possible rubber components include butadiene rubber (BR), ethylene propylene diene monomer rubber (EPDM), butyl rubber (IIR), polyisobutylene rubber, epoxidized natural rubber (ENR), neoprene, synthetic polyisoprene (IR), and polyurethane.

[0059] Reinforcing filler The tread band of the present invention may contain one or more reinforcing filler components. The tread band may be formed from, prepared from, or prepared using a rubber composition containing one or more reinforcing filler components. The reinforcing filler components may be selected from, for example, silica, carbon black, carbon nanotubes, short carbon, polyamide, polyester, natural fibers, calcium carbonate, clay, alumina, aluminosilicate, and any mixture thereof. The use of silica, carbon black, and blends of silica and carbon black is generally preferred.

[0060] As used herein, the term "silica filler" refers to particulate silica. Any known type of particulate silica capable of reinforcing a styrene-butadiene rubber-based composition can be used. As will be understood, known silica materials typically contain a certain proportion of other components (e.g., as impurities), but the main component is silicon dioxide, i.e., SiO2. The silicon dioxide content is generally at least 90% by weight, preferably at least 95% by weight, for example at least 97% by weight. The silica material used in the present invention may be precipitated amorphous silica, wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), fumed silica, calcium silicate, aluminum silicate, magnesium silicate (e.g., Mg2SiO4, MgSiO3), calcium magnesium silicate (CaMgSiO4), and calcium aluminum silicate (e.g., Al2O3·CaO2SiO2). The silica may be used alone or in combination of two or more. The silica is used in the form of discrete particles, i.e., as highly dispersible granules.

[0061] The silica can preferably be selected according to its specific surface area. The surface area of the functionalized silica described herein was measured by the CTAB method in accordance with ASTM D6845 and / or by the BET method in accordance with the method described in Journal of the American Chemical Society, Vol. 60, page 309, February 1938, corresponding to standard NF ISO 5794-1, Appendix D (June 2010). The tread band may include a first silica having a very high surface area. That is, the first silica has a CTAB specific surface area of 230 m~285 m 2 / g, preferably 240 m~270 m 2 / g and / or a BET specific surface area of 260 m~310 m 2 / g, preferably 270 m~300 m 2It may have a BET surface area of ​​ / g. Advantageously, the first silica may be a functionalized ultra-high surface area silica whose surface is functionalized with one or more carboxyl groups. The carboxyl groups may be present as carboxylic acids and / or their derivatives such as salts or esters. The functionalized silica can be prepared according to Example 6 of International Patent Application 2015 / 121333(A1), where the amount of added methylglutaric acid (MGA) is 0.40% by weight (expressed as MGA mixture / SiO2 weight ratio) and the pH is adjusted between 3 and 4.2. The tread band may contain the first silica in an amount of at least 40 phr, more preferably 50 to 80 phr, more preferably 60 to 70 phr, for example, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69 or 70 phr.

[0062] The tread band may contain a second silica layer. This second silica layer may have a very low surface area. That is, the second silica layer may have a surface area of ​​60m to 100m. 2 / g, preferably 65m to 95m 2 CTAB specific surface area and / or 60m~120m² 2 / g, preferably 70m to 110m 2 The tread band may have a BET surface area of ​​1 phr to 30 phr, more preferably 5 phr to 25 phr, more preferably 10 phr to 20 phr, for example, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 phr of second silica.

[0063] The tread band of the present invention comprises a first silica which is the functionalized ultra-high surface area silica described above, and a second silica which is the ultra-low surface area silica described above, and it is particularly advantageous that the amount of the first silica is 60 phr to 70 phr and the amount of the second silica is 10 phr to 20 phr.

[0064] In certain embodiments, the tread band is Two shoulder regions at the axial outer end of the tread band, A central region is identified between the shoulder regions, A row of shoulder elements arranged along the first circumferential rib in each of the shoulder regions, At least two rows of central elements arranged along the second circumferential rib in the central region, It comprises at least three circumferential grooves that separate a first circumferential rib and a second circumferential rib from other circumferential ribs, The central element is separated along its entire axial width by transverse sipes, which define two endpoints at their respective axial outer ends where they intersect with the circumferential grooves. The treadbands are A hydrocarbon polymer additive component, (i) A first hydrocarbon polymer additive, which is a partially hydrogenated C5 resin, in an amount of 1 phr to 30 phr, (ii) comprising a second hydrocarbon polymer additive, which is a fully hydrogenated C9 resin, in an amount of 1 phr to 30 phr, The ratio of the amount of the first hydrocarbon polymer additive to the amount of the second hydrocarbon polymer additive is 2:1 to 1:2, preferably 1:1, and the hydrocarbon polymer additive components are A first styrene-butadiene copolymer functionalized with terminal carboxyl groups, having a styrene content of 21% to 24% by weight of the first styrene-butadiene copolymer and present in an amount of 50 phr to 65 phr, and A second styrene-butadiene copolymer having a styrene content of 32% to 42% by weight of the second styrene-butadiene copolymer and present in an amount of 20 phr to 30 phr, Its surface is functionalized with one or more carboxyl groups present in amounts of 60 phr to 70 phr, and it is 240 m to 270 m. 2 CTAB specific surface area and / or 270m~300m 2 A first silica having a BET surface area of ​​ / g, 65m~95m 2 CTAB specific surface area and / or 70m~110m² / g 2It contains a second silica having a BET surface area of ​​ / g and present in an amount of 10 phr to 20 phr.

[0065] Additional ingredients The tread bands according to the present invention may be made from a rubber composition, prepared from a rubber composition, or prepared using a rubber composition, by using methods known in the art in the manufacture of rubber compositions, such as compounding with other components. These further components may include additional polymers, additional processing aids (such as oils, waxes, and plasticizers), curing systems (such as vulcanizing agents, vulcanization accelerators, and vulcanization accelerator aids), degradation inhibitors (such as antioxidants or ozone degradation inhibitors), pigments, fillers (such as silica and / or carbon black fillers as described herein), compatibilizers for fillers (such as silane coupling agents or coatings as described herein), fibers, and the like.

[0066] Processing aids improve the processability of the composition and include oils such as mineral oils, vegetable oils, synthetic oils, or any mixtures thereof. These may be used in amounts of about 5 phr to 75 phr (including any amount of oil that may be used to increase the polymer), preferably about 10 phr to 50 phr. Typical processing aids include oils such as aromatic oils. Examples of such oils include processed distillate aromatic extracts (TDAEs), residual aromatic extracts (RAEs), mild extract solvates (MESs), and bio-based oilseed derivatives. For example, the oil may be one or more selected from the group consisting of aromatic oils, processed oils such as naphthenic oils and paraffinic oils, vegetable oils such as coconut oil, alkylbenzene oils, and synthetic oils such as castor oil. Preferably, the oil is an aromatic oil such as a residual aromatic extract oil.

[0067] The vulcanizing agent is not particularly limited and may be any vulcanization accelerator commonly known in the art. For example, the vulcanizing agent may be sulfur. The amount of vulcanizing agent is not particularly limited, and an amount effective in achieving satisfactory curing of the composition can be easily selected by those skilled in the art. The vulcanizing agent (e.g., sulfur) can be used in amounts ranging from about 0.1 phr to about 10 phr, preferably about 0.1 phr to about 5 phr, for example, about 0.2 phr to about 3 phr. For example, a rubber composition may contain 0.3 phr to 2 phr, preferably 0.5 phr to 1.5 phr, for example, 0.5 phr to 1 phr of vulcanizing agent.

[0068] The vulcanization accelerator is not particularly limited and may be any vulcanization accelerator commonly known in the art. Examples of accelerators include thiazoles, dithiocarbamates, thiram, guanidines, and sulfonamides. Preferably, the vulcanization accelerator may be a combination of dibenzothiazyl disulfide (MBTS), N-cyclohexyl-2-benzothiazylsulfenamide (CBS), and 1,3-diphenylguanidine (DPG). The amount of vulcanization accelerator to be used in the composition is not particularly limited and may be, for example, in the range of about 0.5 phr to about 10 phr, preferably about 1 phr to about 8 phr, more preferably about 2 phr to about 6 phr. Preferably, the vulcanization accelerator may contain 1 phr to 2 phr of dibenzothiazyl disulfide (MBTS), 0.5 phr to 2 phr of N-cyclohexyl-2-benzothiazyl sulfenamide (CBS), and 1 phr to 3 phr of 1,3-diphenylguanidine (DPG).

[0069] The vulcanization accelerator is not particularly limited and may be any vulcanization accelerator well known to those skilled in the art. For example, the vulcanization accelerator may be zinc oxide (ZnO) and a fatty acid. Preferably, the vulcanization accelerator of the present invention is zinc oxide (ZnO) and stearic acid. The total amount of the vulcanization accelerator is not particularly limited, but may be 1 phr to 10 phr, preferably 1.5 phr to 7 phr, for example 2 phr to 5 phr. Preferably, zinc oxide may be used in an amount of about 1 phr to about 10 phr, preferably about 2 phr to about 5 phr, more preferably about 2 phr to about 3 phr. Stearic acid may be used in an amount of about 1 phr to about 5 phr, preferably about 1.5 phr to about 3 phr.

[0070] A coupling agent may be present that binds to the silanol groups of silica to suppress silica aggregation and also functions to covalently bond the silica filler to the styrene-butadiene copolymer. Typically, the coupling agent is a silane coupling agent, such as a bifunctional silane. Preferably, the silane coupling agent is bis(3-triethoxysilylpropyl)tetrasulfide. A specific example of a silane coupling agent for use in the present invention is Si 69® manufactured by Evonik Industries AG. The amount of silane coupling agent is not particularly limited, but may be 2 to 20 phr, preferably 5 to 18 phr, more preferably 7 to 16 phr, for example 9 to 15 phr.

[0071] The tread band according to the present invention can be prepared by methods well known in the art, and comprises mixing (i.e., compounding) an elastomer, a hydrocarbon polymer additive component, and any other component described herein to produce a rubber composition for subsequent vulcanization.

[0072] In a further embodiment, the present invention provides a method for manufacturing a tread band, comprising the steps of: compounding a rubber composition described herein to form a rubber compound; forming the rubber compound into a desired shape (e.g., molding); and vulcanizing the rubber compound. The method may further include the step of forming one or more circumferential grooves, transverse grooves, and / or sipes (e.g., by cutting) to form tread features, as described below.

[0073] The method of combining the components in the rubber composition to be prepared when preparing the tread band of the present invention is not limited, and any method known in the art may be used. To mold the rubber composition into any desired shape, well-known molding machines such as extruders and press molders can be used. The mixing of components is usually carried out at a stage in which components can be added. A multi-stage mixing process is generally preferred to optimize the dispersion of the silica filler system and may involve the use of two or more mixers, for example, different mixers arranged in series. For example, when mixing a tire tread compound, the mixing process may include an initial mixing stage in which a masterbatch is produced, followed by one or more additional non-productive mixing stages, and finally a curing-initiating mixing stage in which a curing agent (i.e., sulfur or sulfur donor and accelerator) is added. Mixers that can be used are well known in the art and include, for example, open mills or Banbury mixers having tangential or meshing rotors.

[0074] Typically, an initial masterbatch is prepared by mixing the first and second elastomers, hydrocarbon polymer additive components, fillers (if present), additional processing aids (if present), zinc oxide, stearic acid, degradation inhibitors (e.g., antioxidants, ozone degradation inhibitors), pigments, compatibilizers, and coupling agents (if present). After this initial masterbatch, a non-productive mixing step may be performed without adding any additional components. Any non-productive mixing step can be used to further disperse components (e.g., fillers) in the rubber or to reduce the viscosity of the mixed rubber compound. During mixing, the temperature is maintained below a predetermined level to avoid premature crosslinking of the composition. Typically, the temperature can be maintained below 150°C, preferably below 140°C. When preparing the initial masterbatch, mixing may be carried out at a temperature of, for example, about 80°C to about 110°C, for example, about 100°C. In the non-productive mixing step, the temperature may be raised to, for example, about 150°C, for example, about 130°C. If any additional compatibilizers are added during mixing, it may be necessary to mix at a higher temperature to ensure that they react with the silica surface (if any silica fillers are present). The mixing time can vary but can be easily determined by those skilled in the art based on the composition of the mixture and the type of mixer used. Generally, a mixing time of at least 1 minute, preferably 2 to 30 minutes, should be sufficient to obtain the desired homogeneous composition. The final mixing step involves the addition of a curing agent, including accelerators and degradation inhibitors. The temperature of this mixing step is generally lower, for example, in the range of about 40°C to about 60°C, e.g., about 50°C. After this final mixing, a further non-productive mixing step may be performed without adding any additional components. The most suitable type of mixing can be easily selected to achieve a vulcanizable rubber compound. The mixing speed can be easily determined but may be in the range of about 20 rpm to about 100 rpm, e.g., about 30 rpm to about 80 rpm, preferably about 50 rpm. Curing for crosslinking the rubber components can be carried out by well known methods.In the tire industry, for example, uncured rubber (the so-called "green") is manufactured and subsequently cured in a press mold, which simultaneously crosslinks the rubber components and forms the components into the final tire. Vulcanization cures the rubber by crosslinking, mainly via sulfur crosslinking. Methods and conditions for vulcanization to cure rubber compositions are well known to those skilled in the art. Suitable vulcanization conditions typically involve heating to a temperature in the range of 120°C to 200°C, for example 140°C to 180°C, for a duration of 5 minutes to 180 minutes, for example 5 minutes to 120 minutes.

[0075] Treadband Features According to the present invention, the central element is separated along the entire axial width by transverse sipes, which define two endpoints at their respective axial outer ends where they intersect with circumferential grooves. These features improve cornering performance and circumferential stiffness (and therefore traction and braking performance). When combined with the hydrocarbon polymer additive components described herein, additional beneficial and / or synergistic effects are observed in wet performance, wear resistance and rolling resistance, and the balance between these properties.

[0076] Preferably, the imaginary straight extension between the two endpoints defines the inclination angle of the transverse sipe with respect to the axial direction of the tire, with an absolute value in the range of 25° to 50°, more preferably 25° to 45°, and more preferably 30° to 40°. The absolute value may be approximately 35°. The sipe is thus positioned to improve the lateral and circumferential connection of the central element, resulting in improved cornering performance and circumferential stiffness. Also, because the sipe is inclined, it moves gradually and progressively within the tire's contact patch, rather than moving along its entire length. This reduces noise emission.

[0077] Preferably, the virtual straight-line extensions of the transverse sipes of the two central elements are inclined in opposite directions. This is done to balance the direction and magnitude of the lateral forces.

[0078] Preferably, the extension of the transverse sipe along the axial direction between the two endpoints of the transverse sipe is nonlinear. The sipe is thus positioned to improve the lateral and circumferential connection of the central element, resulting in improved cornering performance and circumferential stiffness.

[0079] Preferably, the axial extension between the two endpoints of the transverse sipe is substantially S-shaped. The sipe is thus positioned to improve the lateral and circumferential connection of the central element, resulting in improved cornering performance and circumferential stiffness. This arrangement can also reduce tire noise by resulting in more progressive block impact with the road surface.

[0080] Preferably, the wavy profile is superimposed on an S-shaped extension along the axial direction of the transverse sipe. This is a result of the transverse sipe having a three-dimensional shape. (The wavy profile may be visible on the tread surface, or it may terminate on the inside of the tread at a specific distance below the tread surface.) This results in an increase in localized contact area, which leads to improved braking, and may also lead to a reduction in localized wear.

[0081] Preferably, the transverse sipe has its entire length along its extension between the two endpoints, and the total length of the transverse sipe having a corrugated profile superimposed on the S-shaped extension is at least 20% greater than that of a transverse sipe extending along a straight line between the two endpoints. This minimizes the degree of performance improvement of the sipe compared to a sipe following a straight line between the endpoints.

[0082] As the axially aligned corrugated profile extends radially (i.e., in the depth direction of the sipe), another corrugated profile may be superimposed on the radial extension. In this way, the profile undulates in two directions. Therefore, as the first block moves radially, it comes into contact with the adjacent second block on the other side of the sipe, restricting the radial movement of the first block. This further enhances the aforementioned effect of the axially aligned corrugated profile.

[0083] Preferably, each endpoint of the transverse sipes in each row of the central element has a circumferential offset relative to the nearest circumferential endpoint of the transverse sipes in one or more adjacent rows. In this way, the endpoints of adjacent rows are not aligned along the tire axis. This leads to a reduction in tire noise. The collisions of different endpoints with the road surface are arranged so that they do not all occur simultaneously, and if collisions of all endpoints occur simultaneously, the result will interfere with noise generation.

[0084] Preferably, each endpoint is offset circumferentially with respect to the endpoint closest to each transverse sipe in the row in the circumferential direction.

[0085] Preferably, the transverse sipes have radial extensions on the inside of the tread band along the radial profile, and the radial profile becomes wavy or zigzag as the sipes extend axially.

[0086] Preferably, in the footprint area, the axial width of each shoulder element is greater than the axial width of each central element, and the total number of shoulder elements in each row is greater than the total number of central elements in each row around the entire circumference of the tire. This helps to balance the stiffness of the shoulder and central parts of the tire, avoid rib "collisions," and reduce tire wear. This arrangement can also reduce tire noise by reducing the synchronization of collisions between the central and shoulder elements with the road surface.

[0087] Preferably, the total number of shoulder elements in each column is at most 125%, preferably at most 120%, and more preferably about 115% of the total number of central elements in each column.

[0088] Preferably, the total number of shoulder elements in each column is at least 110% of the total number of central elements in each column.

[0089] In one preferred configuration, the central element is not cut and is preferably separated only by transverse sipes.

[0090] Preferably, the shoulder element is separated by a lug that extends substantially in the axial direction of the tire, the lug having a width in the circumferential direction and having a first portion that intersects with the circumferential groove along the longitudinal extension of the lug and a second portion that extends outward in the axial direction of the tire.

[0091] Preferably, the width of the lug in the first portion intersecting the circumferential groove is smaller than the width of the lug in the second portion. This helps to reduce noise caused by the collision of shoulder elements or blocks on the road surface. More specifically, this helps to reduce so-called air pumping within the lug that generates noise emission. Tire noise can be measured using a pass-through noise test. Conversely, the fact that the lugs intersect the circumferential groove means that adjacent blocks can move relative to each other as they leave the tire contact patch with the road surface, which leads to improved wear performance.

[0092] Preferably, the width of the first portion is in the range of 1 / 12 to 1 / 8 of the width of the second portion. This helps to reduce so-called air pumping within the lug that generates noise emission.

[0093] The width of the first part may be approximately 0.4 mm.

[0094] Preferably, the side walls of the first portion are configured to contact each other as the first portion passes through the tire contact patch with the road surface. In this way, the first portion closes when it is within the contact patch, which helps reduce noise caused by the block impact on the road surface. Conversely, when the block leaves the contact patch, the first portion allows adjacent blocks to move relative to each other, which leads to improved wear performance.

[0095] Preferably, the intersection between the lug and the circumferential groove has a circumferential offset with respect to the endpoint closest to each circumferential direction of the transverse sipe of each row of the central element. This arrangement can reduce tire noise by reducing the synchronization of collisions between the central element and the shoulder element with the road surface.

[0096] Preferably, the lugs in each shoulder region are arranged in this manner.

[0097] In one preferred form, the shoulder element is not cut and is preferably separated only by lugs.

[0098] Referring to Figures 1 to 3, a pneumatic tire 1 is shown. The tire 1 has a tread band 2 for engaging with the road surface in the footprint area of ​​the tire 1.

[0099] As is most clearly shown in Figure 2, the tread band 2 has two shoulder regions 10, 11 at its axially outer ends and a central region 15 identified between the shoulder regions 10, 11. The central region includes the tire equatorial plane.

[0100] Each of the shoulder regions 10 and 11 has shoulder (first) circumferential ribs 20 and 21 that extend along the circumferential direction of the tire 1. Each of the shoulder regions 10 and 11 also has rows of shoulder elements or blocks 20A and 21A arranged along the shoulder circumferential ribs 20 and 21.

[0101] In this embodiment, the central region 15 has three central (second) circumferential ribs 25, 26, and 27 that extend along the circumferential direction of the tire 1. In this embodiment, the central region 15 also has three rows of central elements or blocks 25A, 26A, and 27A arranged along the central circumferential ribs 25, 26, and 27.

[0102] In this embodiment, the tire equatorial plane passes through the central circumferential rib 26, which is a circumferential rib located between the other two central circumferential ribs 25, 27.

[0103] In this embodiment, the tread band 2 has four circumferential grooves 30, 31, 32, 33 that separate the shoulder ribs 20, 21 and the central ribs 25, 26, 27 from other circumferential ribs 20, 21, 25, 26, 27.

[0104] In the footprint area, the axial widths of the shoulder blocks 20A and 21A are greater than the axial widths of the central blocks 25A, 26A, and 27A.

[0105] Furthermore, across the entire circumference of tire 1, the total number of shoulder blocks 20A and 21A in each row is greater than the total number of central blocks 25A, 26A, and 27A in each row. This helps to balance the rigidity of the tire's shoulder and central sections, avoid rib "collisions," and reduce tire wear. This arrangement can also reduce tire noise by reducing the synchronization of collisions between the central and shoulder elements with the road surface.

[0106] In this embodiment, the tire 1 has 80 shoulder blocks 20A, 21A in each row and 70 central blocks 25A, 26A, 27A in each row. However, this is not essential.

[0107] The shoulder blocks 20A and 21A are separated by lugs 40 that extend substantially in the axial direction of the tire 1.

[0108] As best illustrated in Figure 3, the lug 40 has a width in the circumferential direction and comprises a first portion 40A that intersects the circumferential groove 33 along the longitudinal extension of the lug 40, and a second portion 40B that extends outward axially from the first portion 40A to the tire 1. The width of the lug 40 in the first portion 40A is smaller than the width of the lug 40 in the second portion 40B. In particular, the width of the first portion 40A is small enough that the side walls of the first portion 40A come into contact with each other as the first portion 40A passes through the tire contact patch with the road surface. In this way, the first portion 40A closes when it is within the contact patch, which helps to reduce the noise generated by the impact of blocks 20A, 21A onto the road surface.

[0109] The central blocks 25A, 26A, and 27A are separated along their entire axial width by transverse sipes 50, 51, and 52. Each of the transverse sipes 50, 51, and 52 defines two endpoints at their respective axial outer ends where they intersect with the circumferential grooves 30, 31, 32, and 33.

[0110] The imaginary straight extension line 60 between the two endpoints defines the inclination angle θ of the transverse sipe 52 with respect to the axial direction of the tire 1. The absolute value of the angle θ is in the range of 25° to 50°, and in this embodiment it is 35°. The sipe is thus positioned to improve the lateral and circumferential connection of the central element, resulting in improved cornering performance and circumferential stiffness.

[0111] In Figure 3, the virtual straight extension line 60 is shown with respect to the sipe 52 separating the central block 27A. It can be seen that the sipe 51 separating the central block 26A is inclined in the same direction as the sipe 52. However, it can be seen that the sipe 50 separating the central block 25A is inclined in the opposite direction to the sipes 51 and 52.

[0112] Sipes 50, 51, and 52 do not extend in a straight line. This is done to improve the lateral and circumferential connections of the central element, resulting in improved cornering performance and circumferential stiffness.

[0113] The axial extensions between the two endpoints of the transverse sipes 50, 51, and 52 are substantially S-shaped in the plan view. The sipes are thus positioned to improve the lateral and circumferential connection of the central element, resulting in improved cornering performance and circumferential stiffness. This arrangement can also reduce tire noise by resulting in more progressive block impact with the road surface.

[0114] Furthermore, in the plan view, a corrugated profile (a zigzag profile in this embodiment) is superimposed on the S-shaped extensions of the transverse sipes 50, 51, and 52 along their axial directions.

[0115] In this embodiment, each endpoint of the transverse sipes 50, 51, and 52 of the central blocks 25A, 26A, and 27A in each row is offset in the circumferential direction from the nearest endpoint of the transverse sipes 50, 51, and 52 of one or more adjacent rows. Taking the lower transverse sipe 51 of block 26A as an example, in Figure 3 it can be seen that its endpoint is offset from the nearest endpoint of the sipe 50 of block 25A, and also from the nearest endpoint of the sipe 52 of block 27A. This is shown by a dashed line. As another example, taking the lower transverse sipe 52 of block 27A, in Figure 3 it can be seen that its endpoint is offset from the nearest endpoint of the sipe 51 in the adjacent row. Furthermore, one endpoint of the lower sipe 52 (i.e., its upper endpoint) is offset from the nearest endpoint of the upper sipe 50 in a non-adjacent row.

[0116] The transverse sipes 50, 51, and 52 have radial extensions on the inside of the tread band 2 along a radial profile that becomes wavy or zigzag in shape as the sipes 50, 51, and 52 extend axially.

[0117] In this embodiment, the central blocks 25A, 26A, and 27A have no notches and are separated only by transverse sipes 50, 51, and 52. The central blocks 25A, 26A, and 27A also have smooth radial outer surfaces.

[0118] In this embodiment, the intersection of the lug 40 with the circumferential grooves 30, 33 has a circumferential offset relative to the closest endpoints in the circumferential direction of the transverse sipes 50, 51, 52 of each row of central blocks 25A, 26A, 27A. This arrangement can reduce tire noise by reducing the synchronization of collisions between the central blocks and shoulder blocks 25A, 26A, 27A, 20A, 21A and the road surface. Taking the lower lug 40 shown in Figure 3 as an example, it can be seen that its intersection with the circumferential groove 33 is offset from the endpoint of the upper sipe 51 of block 26A. The intersection of the lower lug 40 is also offset from the respective endpoints of the sipes 50, 52 of the other blocks 25A, 27A. In this embodiment, this is at least some of the cases of the lug 40 in the right shoulder region shown in Figure 3. This is also at least some of the cases of the lug 40 in the left shoulder region shown in Figure 3.

[0119] As shown in Figure 3, the lower lug 40 extends substantially in a straight line. Furthermore, although not required in this embodiment, the inclination angle of the lug 40 with respect to the tire axis is smaller than the inclination angle of the imaginary straight line extension between the two endpoints of the transverse sipes 50, 51, and 52. However, it is not required that all lugs 40 and all transverse sipes 50, 51, and 52 have this relationship; it is possible that only some of the lugs 40 and the transverse sipes 50, 51, and 52 have this relationship. Although not required in this embodiment, the inclination angle of the lug 40 with respect to the tire axis is approximately 15°.

[0120] In this embodiment, there are three central circumferential ribs 25, 26, 27, three rows of central blocks 25A, 26A, 27A, and four circumferential grooves 30, 31, 32, 33. However, this is not mandatory, and the number of these ribs, rows, and circumferential grooves may differ.

[0121] Figure 4 shows the transverse sipe-forming portion 100 of the mold for tire 1. The shape of the transverse sipe-forming portion 100 corresponds to the sipes to be formed, for example, sipes 50, 51, and 52. As seen in Figure 4, as the axially oriented wavy profile extends radially (i.e., in the depth direction of the sipe), another wavy profile is superimposed on the radial extension. In this way, the profile undulates in two directions.

[0122] Preferred embodiments of the present invention are described purely as examples, and various modifications, additions, and / or omissions are presented to those skilled in the art, all of which form part of the present invention.

[0123] In a particular embodiment, the tread band has two shoulder regions at the axial outer end of the tread band, A central region is identified between the shoulder regions, A row of shoulder elements arranged along the first circumferential rib in each of the shoulder regions, At least two rows of central elements arranged along the second circumferential rib in the central region, It comprises at least three circumferential grooves that separate a first circumferential rib and a second circumferential rib from other circumferential ribs, The central element is separated along its entire axial width by transverse sipes, which define two endpoints at their respective axial outer ends where they intersect with the circumferential grooves. The axial extension of a transverse sipe between its two endpoints is substantially S-shaped, and the wavy profile is superimposed on the axial S-shaped extension of the transverse sipe; the transverse sipe has a total length along its extensions between its two endpoints, and the total length of a transverse sipe with a wavy profile superimposed on the S-shaped extension is at least 20% greater than that of a transverse sipe extending along a straight line between its two endpoints; the transverse sipe has a radial extension on the inside of the tread band along its radial profile, and the radial profile becomes wavy or zigzag as the sipe extends axially; The treadbands are (i) A first hydrocarbon polymer additive which is a partially hydrogenated C5 resin, (ii) A second hydrocarbon polymer additive which is a fully hydrogenated resin selected from the group consisting of hydrogenated C5 resins, hydrogenated C5 / C9 copolymer resins, hydrogenated C9 resins, and combinations thereof, and / or prepared therefrom.

[0124] In a particular embodiment, the tread band has two shoulder regions at the axial outer end of the tread band, A central region is identified between the shoulder regions, A row of shoulder elements arranged along the first circumferential rib in each of the shoulder regions, At least two rows of central elements arranged along the second circumferential rib in the central region, It comprises at least three circumferential grooves that separate a first circumferential rib and a second circumferential rib from other circumferential ribs, The central element is separated along its entire axial width by transverse sipes, which define two endpoints at their respective axial outer ends where they intersect with the circumferential grooves. The axial extension of a transverse sipe between its two endpoints is substantially S-shaped, and the wavy profile is superimposed on the axial S-shaped extension of the transverse sipe; the transverse sipe has a total length along its extensions between its two endpoints, and the total length of a transverse sipe with a wavy profile superimposed on the S-shaped extension is at least 20% greater than that of a transverse sipe extending along a straight line between its two endpoints; the transverse sipe has a radial extension on the inside of the tread band along its radial profile, and the radial profile becomes wavy or zigzag as the sipe extends axially; The treadbands are A hydrocarbon polymer additive component, (i) A first hydrocarbon polymer additive, which is a partially hydrogenated C5 resin, in an amount of 1 phr to 30 phr, (ii) comprising a second hydrocarbon polymer additive, which is a fully hydrogenated C9 resin, in an amount of 1 phr to 30 phr, The hydrocarbon polymer additive component has a ratio of 2:1 to 1:2 between the amount of the first hydrocarbon polymer additive and the amount of the second hydrocarbon polymer additive. A first styrene-butadiene copolymer functionalized with terminal carboxyl groups, having a styrene content of 21% to 24% by weight of the first styrene-butadiene copolymer and present in an amount of 50 phr to 65 phr, and A second styrene-butadiene copolymer having a styrene content of 32% to 42% by weight of the second styrene-butadiene copolymer and present in an amount of 20 phr to 30 phr, A quantity of 10 phr to 30 phr of natural rubber, Its surface is functionalized with one or more carboxyl groups present in amounts of 60 phr to 70 phr, and it is 240 m to 270 m. 2 CTAB specific surface area and / or 270m~300m 2 A first silica having a BET surface area of ​​ / g, 65m~95m 2 CTAB specific surface area and / or 70m~110m² / g 2 It contains and / or is prepared from a second silica having a BET surface area of ​​ / g and present in an amount of 10 phr to 20 phr.

[0125] Further features of the tread band of the present invention are described below.

[0126] The shoulder element may be separated substantially by a lug extending axially from the tire, the lug having a width in the circumferential direction and having a first portion along its longitudinal extension that intersects with a circumferential groove and a second portion extending axially outward from the tire, wherein the width of the first portion of the lug intersecting with the circumferential groove is smaller than the width of the second portion of the lug.

[0127] In the footprint region, the axial width of each shoulder element may be greater than the axial width of each central element. Across the entire circumference of a tire with a tread band, the total number of shoulder elements in each row is greater than the total number of central elements in each row.

[0128] In the footprint region, the void ratio of the shoulder region may be at least 3% smaller than the void ratio of the central region.

[0129] The present invention is illustrated by the following non-limiting embodiments.

[0130] Examples Measurement method Modulus of elasticity (E') The modulus of elasticity (E') is used to evaluate grip performance. Dynamic physical tests to determine E' at 30°C are performed according to ISO 4664 standard.

[0131] Loss factor (tanδ) Rolling resistance and wet traction are evaluated using loss factors (tangent δ, or tanδ) at different temperatures.

[0132] A lower tanδ at lower temperatures is an indicator of wet traction. An increase in tanδ at lower temperatures compared to a control compound correlates with an improvement in the wet traction of the tread compound. When developing rubber compositions for tire treads to improve tire rolling resistance, it is typical to consider the loss tangent (tanδ) around 60°C as an indicator. By using a rubber composition with a low tanδ around 60°C in the tread rubber, tire heat generation can be suppressed, reducing rolling resistance and improving tire fuel efficiency. Therefore, tanδ at 60°C is an indicator of rolling resistance (RR). A lower result compared to a control compound indicates a reduction in rolling resistance. Dynamic physical tests to determine tanδ are performed according to the ISO 4664 standard.

[0133] Wear resistance Abrasion resistance is determined according to the ISO 4649 standard.

[0134] Tire testing Tire data is obtained from tests on vehicles fitted with tires having tire treads manufactured using a rubber composition. Three different tire specifications are manufactured, each differing only in the rubber tread compound, i.e., all other variables are kept constant. The vehicle is driven on the road surface for at least 10,000 km, and then the degree of wear (mm) is measured (reduction in groove depth).

[0135] General method The tire compound was prepared according to the following general method. The following components were blended in the amounts listed in Table 1 below.

[0136] component Elastomer: Functionalized solution styrene-butadiene rubber (Fxt s-SBR 1) (prepared according to Example 3 of International Patent Application No. 2014 / 173706(A1)) Solution polymerization SBR (s-SBR) (EUROPRENE® SOL RX 74618) Natural rubber Emulsified polymerized styrene-butadiene rubber (e-SBR) (EUROPRENE® 1739 BA, bulked with 37.5 phr of TDAE oil) Functionalized solution styrene-butadiene rubber (Fxt s-SBR 2) (EUROPRENE® SOL R 72616) Silica: Functionalized ultra-high surface area silica (Fxt VHSA-SiO2) (prepared according to Example 6 of International Patent Application No. 2015 / 121333(A1)) Silica (STD-SiO2) (Ultrasil VN3) Ultra-low surface area silica (VLSA-SiO2) (ZEOSIL 1085 GR) Hydrocarbon polymer additives (resins): C5 partially hydrogenated resin (C5 resin) C9 fully hydrogenated resin (C9 resin) Further additives: Carbon Black (Corax® N234) Silane (Evonik Industries AG Si 69 (registered trademark)) Octyl oleate Residual Aromatic Extracted Oil (RAE) sulfur 1,3-Diphenylguanidine (DPG) Dibenzothiadyl disulfide (MBTS) N-cyclohexyl-2-benzothiadylsulfenamide (CBS) Zinc oxide (ZnO) Stearic acid.

[0137] [Table 1]

[0138] Compound A contains only partially hydrogenated C5 resin (C5 resin), Compound B contains only fully hydrogenated C9 resin (C9 resin), and Compound C contains both C5 resin and C9 resin.

[0139] Tire treads were prepared using the compounds listed in Table 1 by extrusion molding, a method known to those skilled in the art. The wear resistance, wet performance, and rolling resistance of these tires were measured using the method described above. The results of these measurements are shown in Table 2 for Comparative Example 1, where all listed characteristic values ​​were normalized to 100. A viscoelastic value greater than 100 indicates an improvement in that characteristic, while a value less than 100 indicates a decrease in that characteristic.

[0140] [Table 2]

[0141] The results in Table 2 demonstrate a significant improvement in performance (particularly wear resistance) when a tire having the third alternative sipe of the present invention is prepared from a compound containing both the preferred C5 and C9 resins. As can be seen from Table 2, a tire prepared from a compound containing both C5 and C9 resins but having a different sipe than the third alternative does not perform similarly, nor does a tire prepared from a compound containing only one of the resins but having the sipe of the third alternative. This demonstrates a synergistic improvement when C5 and C9 resins are combined with the sipes of the present invention.

Claims

1. A tread band for a tire suitable for engaging with the road surface in the footprint area, Two shoulder regions at the axial outer end of the tread band, A central region is identified between the shoulder region, In each of the shoulder regions, a row of shoulder elements is arranged along the first circumferential rib, In the central region, at least two rows of central elements are arranged along the second circumferential rib, It comprises at least three circumferential grooves that separate the first circumferential rib and the second circumferential rib from other circumferential ribs, The central elements are separated along their entire axial width by transverse sipes, and the transverse sipes define two endpoints at their respective axial outer ends where they intersect the circumferential grooves. The E treadband is (i) Partially hydrogenated C containing less than 100% and 5% or more olefin protons ５ A first hydrocarbon polymer additive which is a resin, (ii) A second hydrocarbon polymer additive which is a fully hydrogenated resin, wherein the fully hydrogenated resin contains less than 5% olefin protons and hydrogenated C ５ Resins, hydrogenated carbon ５ / C ９ Copolymer resin, hydrogenated carbon ９ A tread band (2) further comprising a second hydrocarbon polymer additive selected from the group consisting of resins and combinations thereof.

2. The first hydrocarbon polymer additive is a partially hydrogenated C ５ The resin is a second hydrocarbon polymer additive, and the second hydrocarbon polymer additive is fully hydrogenated C ９ The tread band according to claim 1, wherein it is made of resin.

3. The first hydrocarbon polymer additive is a partially hydrogenated C ５ The tread band according to claim 1 or 2, wherein the tread band is a dicyclopentadiene (DCPD) copolymer.

4. The first hydrocarbon polymer additive has the following characteristics, namely, Olefin proton content of less than 10 mol%, Softening point of 110°C or higher, Weight-average molecular weight of 200 g / mol to 2000 g / mol, and / or A partially hydrogenated C resin having a glass transition temperature (T) of 50 °C or higher, one or more of which are present, the tread band according to claim 1. ｇ ), ５ ​

5. The second hydrocarbon polymer additive is a fully hydrogenated C ９ The tread band according to claim 1, wherein it is made of resin.

6. The aforementioned hydrogenated C ９ The resin has the following characteristics, namely, Softening point is 100°C or higher, Weight-average molecular weight (Mw) of 700 g / mol to 1500 g / mol, and / or Glass transition temperature (T) of at least 50°C ｇ The treadband according to claim 1, having one or more of the following:

7. The tread band according to claim 1, wherein the ratio of the amount of the first hydrocarbon polymer additive to the amount of the second hydrocarbon polymer additive is 10:1 to 1:

10.

8. The tread band according to claim 1, wherein the imaginary straight extension between the two endpoints defines the inclination angle of the transverse sipe with respect to the axial direction of the tire, the absolute value of which is in the range of 25° to 50°.

9. The tread band according to claim 8, wherein the extension along the axial direction between the two endpoints of the transverse sipe is substantially S-shaped.

10. The tread band according to claim 1, wherein each endpoint of the transverse sipe of each row of the central element has a circumferential offset with respect to the endpoint closest to each circumferential point of the transverse sipe of one or more adjacent rows.

11. The tread band according to claim 1, wherein the transverse sipe has a radial extension on the inside of the tread band along the radial profile, and the radial profile becomes wavy or zigzag in shape as the transverse sipe extends in the axial direction.

12. The tread band according to claim 1, further comprising a first elastomer component containing one or more styrene-butadiene copolymers.

13. The tread band according to claim 1, further comprising a second elastomer component containing natural rubber.

14. The tread band according to claim 1, wherein the tread band comprises a first silica functionalized with one or more carboxyl groups.

15. The first silica is 230 m² / g to 285 m ２ The tread band according to claim 14, having a CTAB specific surface area of ​​1 / g.

16. The tread band according to claim 1, wherein the tread band contains a second silica.

17. The E treadband is A first styrene-butadiene copolymer functionalized with terminal carboxyl groups, having a styrene content of 21% to 24% by weight of the first styrene-butadiene copolymer and present in an amount of 50 phr to 65 phr, A second styrene-butadiene copolymer having a styrene content of 32% to 42% by weight of the second styrene-butadiene copolymer and present in an amount of 20 phr to 30 phr, A quantity of natural rubber ranging from 10 phr to 30 phr, Its surface is functionalized with one or more carboxyl groups present in amounts of 60 phr to 70 phr, and it is 240 m² / g to 270 m ２ CTAB specific surface area per g and / or 270 m² / g to 300 m² ２ A first silica having a BET surface area of ​​ / g, 65m 2 / g ~ 95m ２ CTAB specific surface area per g and / or 70 m² / g to 110 m² ２ A tread band according to claim 1, comprising a second silica having a BET surface area of ​​10 phr to 20 phr and having a BET surface area of ​​1 / g.

18. A pneumatic tire comprising the tread band described in claim 1.

Images