Tread band for pneumatic tire and tire including same

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 including 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, has a beneficial and / or synergistic effect on the wet performance, rolling resistance, and wear resistance of a tire including the tread band. [Background technology]

[0002] In order 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 tires have good grip performance, especially on wet roads (i.e., wet performance). High wear resistance is also an important factor for a long tire service life. Wet performance ("WET"), rolling resistance ("RR"), and wear resistance ("WEAR") together are known as the "magic triangle" of viscoelastic properties. There is a continuing need to produce tires with an improved balance between these properties.

[0003] The chemical composition of a tire can be modified to adjust its dynamic and mechanical properties. In an attempt to achieve a better wet / roll-relief / wear balance, the use of modified rubbers and mixtures of rubber with various reinforcing fillers has been proposed. However, improving any one of these tire properties often adversely affects at least one of the other properties. For example, it is difficult to improve a tire's wet performance without adversely affecting its rolling resistance and wear resistance. Similarly, increasing the amount of reinforcing fillers improves wear performance, which reduces rolling resistance.

[0004] Hydrocarbon resins are widely used as processing aids that can 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, including aliphatic, aromatic, partially hydrogenated, and fully hydrogenated resins, are known for use in producing rubber compositions for tire treads. Combinations of different hydrocarbon resins have been proposed. For example, U.S. Patent Application Publication No. 2019 / 0092937 proposes blending 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 configuration of a tire tread, particularly the size and shape of the portion that contacts the road (contact patch), also affects its performance. Tire treads are generally cut to form tread elements. Circumferential grooves in the tread can improve water evacuation (thus affecting 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 whose chemical composition and physical configuration are optimized in tandem to improve tire performance.

[0006] The present invention is directed to fulfilling an unmet need in the art and solving problems associated with existing tires. Summary of the Invention

[0007] The present invention is based on the discovery that optimizing the chemical composition and physical form of a tread band can have a beneficial and / or synergistic effect 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] Viewed from a first aspect, the present invention provides a tread band for a tire adapted to engage a road surface in a footprint area, comprising: two shoulder regions at the axially outer ends of the tread band; a central region identified between the shoulder regions; a row of shoulder elements disposed along the first circumferential rib in each of the shoulder regions; at least two rows of central elements disposed along the second circumferential rib in a central region; at least three circumferential grooves separating the first and second circumferential ribs from one another; the central elements are separated along their entire axial width by transverse sipes, the transverse sipes defining two end points at their respective axially outer ends where they intersect the circumferential grooves; The tread band is (i) a first hydrocarbon polymer additive that is a partially hydrogenated C5 resin; and (ii) a second hydrocarbon polymer additive that 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 from a second aspect, the 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 explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view of a tire according to a preferred embodiment of the present invention. [Figure 2] FIG. 2 is a front view of the tire of FIG. 1. [Figure 3] FIG. 2 is a partial front view of the tire of FIG. 1. [Figure 4] FIG. 2 is a schematic view of a transverse sipe forming portion of a mold for the tire of FIG. 1. [Figure 5] FIG. 1 is a schematic diagram of a first alternative sipe forming mold for forming a first alternative transverse sipe having a protrusion in a central region of the base of the sipe, the protrusion being rounded at its base and upper edge and protruding partially upward from the base of the sipe. [Figure 6] FIG. 10 is a schematic diagram of a second alternative sipe forming mold for forming a second alternative transverse sipe having a series of raised ellipses linearly arranged along the length of the sipe. [Figure 7] FIG. 10 is a schematic diagram of a third alternative sipe forming mold for forming a third alternative transverse sipe having longitudinal sinusoidal features at the base of the sipe. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention relates to a tread band for a tire adapted to engage a road surface in a footprint area, comprising: two shoulder regions at the axially outer ends of the tread band; a central region identified between the shoulder regions; a row of shoulder elements disposed along the first circumferential rib in each of the shoulder regions; at least two rows of central elements disposed along the second circumferential rib in a central region; at least three circumferential grooves separating the first and second circumferential ribs from one another; the central elements are separated along their entire axial width by transverse sipes, the transverse sipes defining two end points at their respective axially outer ends where they intersect the circumferential grooves; The tread band is (i) a first hydrocarbon polymer additive that is a partially hydrogenated C5 resin; and (ii) 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 characteristics of the 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 a tread band having different physical characteristics and / or not containing the hydrocarbon polymer additive. The beneficial effect of combining the physical characteristics of the tread band with a hydrocarbon polymer additive may be a synergistic effect.

[0014] Hydrocarbon Polymer Additive Component The tread band described herein includes a hydrocarbon polymer additive component and may be formed or prepared from a composition including the hydrocarbon polymer additive component. As used herein, the term "hydrocarbon polymer additive" refers to a hydrocarbon resin and is used interchangeably herein with the term "hydrocarbon resin." The hydrocarbon polymer additive component includes a first hydrocarbon polymer additive that is a partially hydrogenated C5 resin and a second hydrocarbon polymer additive that is a fully hydrogenated resin selected from hydrogenated C5 resins, hydrogenated C5 / C9 copolymer resins, hydrogenated C9 resins, and combinations thereof. While additional resins may be present, in one embodiment, the only resins present are the first hydrocarbon resin and the second hydrocarbon resin described herein. Exemplary combinations of the first hydrocarbon polymer additive and the second hydrocarbon polymer additive 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. The hydrogenation may be partial, thus resulting in a "partially hydrogenated resin," or 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% olefinic protons, which 1The hydrogenation degree can be determined by H NMR spectroscopy. Partially hydrogenated resins are well known in the art and can have different degrees of hydrogenation. In some embodiments, the partially hydrogenated resin can contain less than 95% olefinic protons, more preferably less than 90%. In some embodiments, it can contain less than 75% olefinic protons, e.g., less than 50% olefinic protons. In some embodiments, the partially hydrogenated resin can contain less than 40% olefinic protons, less than 25% olefinic protons, less than 15% olefinic protons, or less than 10% olefinic protons. For example, it can contain less than 9%, less than 8%, less than 7%, or less than 6% olefinic protons. In one embodiment, the partially hydrogenated resin can contain about 5% or more olefinic protons. For example, it can contain 5% to 90% olefinic protons. In one embodiment, the partially hydrogenated resin can contain about 5% olefinic protons, i.e., about 95% hydrogenated.

[0017] As used herein, the term "fully hydrogenated" means that the resin component contains less than 5% olefinic protons. In some embodiments, a fully hydrogenated resin may contain less than 4%, preferably less than 3%, more preferably less than 2%, e.g., less than 1%, less than 0.5%, or less than 0.1%, e.g., less than 0.05%, of olefinic protons.

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

[0019] Hydrogenated resins include resins produced by reductive hydrogenation of resins containing aromatic components. As will be understood, any reference herein to olefinic protons is intended to include any protons that may be present as part of an aromatic ring system. Percentages recited herein for olefinic proton content and degree of hydrogenation refer to mole percent.

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

[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 cracked naphtha feed containing C5 monomers. C5 monomers include olefins, linear conjugated diolefins, and cyclic conjugated diolefins. Other monomers may also be 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. When present, DCPD monomers 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, e.g., less than about 2% by weight. Preferably, the C5 resin may comprise monomer units derived from a C5 monomer and DCPD. Thus, a partially hydrogenated C5 resin may comprise a partially hydrogenated copolymer of C5 and dicyclopentadiene DCPD, preferably with DCPD present in an amount less than 5% by weight of the C5 and DCPD monomers. However, in another embodiment, the feed used to provide the C5 resin may exclude any DCPD monomer. This monomer can be removed from the feed stream by methods commonly known in the art. Thus, in one embodiment, the C5 resin may consist essentially of monomer units derived from a 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 and ball method. Unless otherwise specified, the softening points listed herein are "ring and ball softening points," i.e., the temperature at which the ball falls when measuring the softening point using a ring and ball softening point apparatus 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 an increase in tan δ 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 from 115°C to 145°C, more preferably from 120°C to 140°C, more preferably from 125°C to 135°C, such as 125, 126, 127, 128, 129, 230, 131, 132, 133, 134, or 135°C.

[0024] In view of resin miscibility, the weight average molecular weight of the partially hydrogenated C5 resin generally ranges from 200 g / mol to 2000 g / mol. Unless otherwise specified, references to molecular weight herein 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 greater, preferably 600 g / mol or greater, and more preferably 800 g / mol or greater. 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 g / mol or less, and even more preferably 1400 g / mol or less. For example, the weight average molecular weight of the partially hydrogenated C5 resin may be from 600 g / mol to 1600 g / mol, more preferably from 800 g / mol to 1400 g / mol, more preferably from 1000 g / mol to 1200 g / mol, such as 1000, 1100, or 1200 g / mol.

[0025] The glass transition temperature (T g ) may be 50°C or higher, preferably 60°C to 90°C, more preferably 65°C to 85°C. g Values ​​are determined using differential scanning calorimetry (DSC) with a starting temperature of -140°C and a temperature ramp 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 C5 fractions obtained by thermal cracking of naphtha in the petrochemical industry. C5 fractions typically contain 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). When DCPD is present, it is generally present in small amounts, for example, less than 5% by weight, e.g., less than 2% by weight, of the C5-containing fraction. Any of these resins can be subjected to partial reductive hydrogenation to produce a partially hydrogenated C5 resin, e.g., one containing 3% to 9% olefinic protons, preferably 4% to 8% olefinic protons, and more preferably 4% to 6% olefinic protons. In one embodiment, the partially hydrogenated C5 resin contains about 5% olefinic protons. Commercially available partially hydrogenated C5 resins can be used.

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

[0028] The second hydrocarbon polymer additive is selected from a fully hydrogenated C5 resin, a fully hydrogenated C5 / C9 copolymer resin, a fully hydrogenated C9 resin, 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 a specific embodiment, 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 an increase in tan δ 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, such as 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, or 130°C.

[0030] In consideration of resin miscibility, the weight average molecular weight of the second hydrocarbon resin generally ranges from 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 g / mol or less. In one embodiment, the second hydrocarbon resin has a softening point greater 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 greater 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 a resin to substantially complete (e.g., complete) reductive hydrogenation.

[0031] Glass transition temperature (T g ) 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. Examples of C5 resins that can be used to produce fully hydrogenated C5 resins include aliphatic petroleum resins obtained by (co)polymerizing C5 fractions obtained by thermal cracking of naphtha in the petrochemical industry. C5 fractions typically contain 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. They 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-C 11 Examples of suitable C5 / C9 resins include solid polymers obtained by polymerization using a Friedel-Crafts catalyst such as BF3, and more specifically, copolymers containing styrene, vinyltoluene, α-methylstyrene, indene, or the like as the main component. From the viewpoint of compatibility with the rubber component, C5 / C9 resins are preferably resins containing a small amount of C9 or higher 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 weight of the resin.

[0034] As the C5 / C9 resin, commercially available products can be used.

[0035] The term "C9 resin" refers to a C9 synthetic petroleum resin, including, for example, a polymer obtained by polymerization using a Friedel-Crafts catalyst such as AlCl3 or BF3. Examples of C9 resins include copolymers containing indene, styrene, α-methylstyrene, vinyltoluene, etc. as the main component.

[0036] The olefinic 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% olefinic protons, e.g., 0 mol% olefinic 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 greater than 100°C.

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

[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 dispersion of the components, the tread band may include a first hydrocarbon polymer additive in an amount of from 1 phr to 30 phr, preferably from 5 phr to 10 phr, for example, 5, 6, 7, 8, 9 or 10 phr. The tread band may include a second hydrocarbon polymer additive in an amount of from 1 phr to 30 phr, preferably from 5 phr to 10 phr, for example, 5, 6, 7, 8, 9 or 10 phr. The tread band includes the first hydrocarbon polymer additive and the second hydrocarbon polymer additive in a total amount of from 2 phr to 60 phr, more preferably from 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 in which the components of a composition are measured relative to the sum of all rubber (i.e., elastomer) components. The total parts of the rubber components are defined as 100 phr, and all other components are defined as ratios to 100 parts rubber, expressed in "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 dispersion of the components and therefore improve tire performance, the tread band may comprise a first hydrocarbon polymer additive which is a partially hydrogenated C5 resin having the characteristics of the preferred embodiment of the partially hydrogenated C5 resin described herein above in an amount of from 6 phr to 10 phr, and a second hydrocarbon polymer additive which is a fully hydrogenated C9 resin having the characteristics of the preferred embodiment of the hydrogenated C9 resin described herein above in an amount of from 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 include one or more elastomer components. The tread band may also be formed from, prepared from, or prepared with a rubber composition including 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, such as copolymerization of the corresponding monomers in emulsion, suspension, or solution. In one set of embodiments, 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 as an aqueous emulsion. Such methods are well known and understood by those skilled in the art.

[0043] In the present invention, the tread band may comprise and / or 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 from 10% to 40% by weight (by weight of the first SBR copolymer), preferably from 10% to 30% by weight, more preferably from 15% to 25% by weight, and even more preferably from 21% to 24% by weight, for example about 21% by weight. 1 It can be determined by H-NMR.

[0045] The first styrene-butadiene copolymer may preferably be an end-group functionalized copolymer that can have an interactive and / or synergistic effect on the properties of the tread band, resulting in advantageous properties. Specifically, when a silica filler system is present, the interaction between the end-group functionalized styrene-butadiene copolymer and the silica, which may be synergistic, can result in improved dispersion of the filler system in the rubber composition and products made therefrom. An "end-group functionalized" SBR is sometimes referred to as an "end-modified" SBR. In some embodiments, the styrene-butadiene copolymer may be an end-group functionalized SSBR. Preferably, the first styrene-butadiene copolymer is functionalized with a terminal carboxyl group. The end-group functionalized SSBR copolymer was prepared according to Example 3 of International Patent Application No. 2014 / 173706 A1, as described below.

[0046] A 20-liter inerted reactor was charged with 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), 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 butyllithium, and the reactor contents were then heated to 60°C for an additional 20 minutes to cap the anionic ends of the polymer chains. Twenty minutes after the addition of the hexamethylcyclotrisiloxane, an equimolar amount of 2,2-dimethyl-1-oxa-4-thia-2-silacyclohexan-6-one (as a solution in toluene) was added to the butyllithium and hexamethylcyclotrisiloxane, and the mixture was heated to 60°C for an additional 20 minutes. The rubber solution was drained and stabilized by the addition of Irganox® 1520 (2,4-bis(octyllithiomethyl)-6-methylphenol) (3 g), and the solvent was removed by steam stripping. The rubber crumb was dried under vacuum 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 parts 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 comprises the first styrene-butadiene copolymer in an amount of at least 30 phr, more preferably from 40 phr to 70 phr, more preferably from 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 from 25% to 50%, preferably from 32% to 42%, 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-extended and thus may have an oil content of from 10 to 35 parts per 100 parts of the second styrene-butadiene copolymer, preferably from 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 comprise the second styrene-butadiene copolymer in an amount of at least 10 phr, more preferably from 15 phr to 35 phr, more preferably from 20 phr to 30 phr, for example 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 phr.

[0056] The tread band may further comprise a second elastomer component comprising natural rubber. Natural rubber is well known for its use in the manufacture of tires. The natural rubber used in the present 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 Singapore Rubber (SSR), Standard Lankan 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 from 10 phr to 30 phr, more preferably from 15 phr to 25 phr, for example 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 phr.

[0058] Other rubber components that may be present 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 Fillers The tread band of the present invention may include one or more reinforcing filler components. The tread band may be formed from, prepared from, or prepared with a rubber composition including 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, aluminosilicates, and any mixtures thereof. The use of silica, carbon black, and blends of silica and carbon black is generally preferred.

[0060] The term "silica filler" as used herein refers to particulate silica. Any known type of particulate silica capable of reinforcing styrene-butadiene rubber-based compositions 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). Silica may be used alone or in combination of two or more types. Silica is used in the form of discrete particles, i.e., as highly dispersible granules.

[0061] The silica may be preferably selected according to its specific surface area. The surface area of ​​the functionalized silica described herein is measured by the CTAB method according to ASTM D6845 and / or by the BET method according to the method described in the Journal of the American Chemical Society, Vol. 60, p. 309, February 1938, which corresponds to standard NF ISO 5794-1, Appendix D (June 2010). The tread band may comprise a first silica having a very high surface area, i.e., the first silica has a surface area of ​​230 m to 285 m. 2 / g, preferably 240m to 270m 2 / g CTAB specific surface area and / or 260m to 310m 2 / g, preferably 270m to 300m 2The first silica may have a BET surface area of ​​0.1 to 0.25 g / g. Advantageously, the first silica may be a functionalized ultra-high surface area silica, the surface of which is functionalized with one or more carboxyl groups. The carboxyl groups may be present as carboxylic acids and / or as derivatives thereof, such as salts or esters. The functionalized silica may be prepared according to Example 6 of International Patent Application No. 2015 / 121333 (A1), in which the amount of methyl glutaric acid (MGA) added was 0.40 wt. % (expressed as MGA mixture / SiO2 weight ratio) and the pH was adjusted to between 3 and 4.2. The tread band may comprise the first silica in an amount of at least 40 phr, more preferably 50 phr to 80 phr, more preferably 60 phr to 70 phr, for example 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, or 70 phr.

[0062] The tread band may include a second silica. The second silica may have a very low surface area, i.e., between 60 and 100 m 2 / g, preferably 65m to 95m 2 / g CTAB specific surface area and / or 60m to 120m 2 / g, preferably 70m to 110m 2 The tread band may comprise the second silica in an amount of from 1 phr to 30 phr, more preferably from 5 phr to 25 phr, more preferably from 10 phr to 20 phr, for example 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 phr.

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

[0064] In a particular embodiment, the tread band comprises: two shoulder regions at the axially outer ends of the tread band; a central region identified between the shoulder regions; a row of shoulder elements disposed along the first circumferential rib in each of the shoulder regions; at least two rows of central elements disposed along the second circumferential rib in a central region; at least three circumferential grooves separating the first and second circumferential ribs from one another; the central elements are separated along their entire axial width by transverse sipes, the transverse sipes defining two end points at their respective axially outer ends where they intersect the circumferential grooves; The tread band is 1. A hydrocarbon polymer additive component comprising: (i) a first hydrocarbon polymer additive that is a partially hydrogenated C5 resin in an amount of 1 phr to 30 phr; (ii) a second hydrocarbon polymer additive which is a fully hydrogenated C9 resin in an amount of from 1 phr to 30 phr; a hydrocarbon polymer additive component, wherein 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; a first styrene butadiene copolymer functionalized with terminal carboxyl groups, the first styrene butadiene copolymer 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; Its surface is functionalized with one or more carboxyl groups, present in an amount of 60 phr to 70 phr, and has a surface area of ​​240 m to 270 m 2 / g CTAB specific surface area and / or 270m-300m 2 a first silica having a BET surface area of ​​1 / g; 65m~95m 2 / g CTAB specific surface area and / or 70m to 110m 2and a second silica having a BET surface area of ​​10 phr to 20 phr.

[0065] Additional ingredients The tread band according to the present invention may be made from or prepared from the rubber composition using methods known in the art for making rubber compositions, such as compounding with other ingredients. These additional ingredients may include additional polymers, additional processing aids (such as oils, waxes, and plasticizers), cure systems (such as vulcanizing agents, vulcanization accelerators, and vulcanization accelerator co-agents), antidegradants (such as antioxidants or antiozonants), pigments, fillers (such as the silica and / or carbon black fillers described herein), compatibilizers for fillers (such as the silane coupling agents or coating agents described herein), fibers, etc.

[0066] Processing aids improve the processability of the composition and include oils such as mineral oils, vegetable oils, synthetic oils, or any mixture thereof. These may be used in amounts of about 5 phr to 75 phr (including any oils that may be used to extend the polymer), preferably about 10 phr to 50 phr. Typical processing aids include oils such as aromatic oils. Examples of such oils include treated distillate aromatic extract (TDAE), residual aromatic extract (RAE), mild extract solvate (MES), and bio-based oilseed derivatives. For example, the oil may be one or more selected from the group consisting of processed oils such as aromatic oils, naphthenic oils, 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 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 to achieve satisfactory cure of the composition can be readily selected by one skilled in the art. The vulcanizing agent (e.g., sulfur) may be used in an amount ranging from about 0.1 phr to about 10 phr, preferably from about 0.1 phr to about 5 phr, for example, from about 0.2 phr to about 3 phr. For example, the 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 the 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, thiurams, guanidines, and sulfonamides. Preferably, the vulcanization accelerator is a combination of dibenzothiazyl disulfide (MBTS), N-cyclohexyl-2-benzothiazyl sulfenamide (CBS), and 1,3-diphenylguanidine (DPG). The amount of the vulcanization accelerator 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, and more preferably about 2 phr to about 6 phr. Preferably, the vulcanization accelerator may include dibenzothiazyl disulfide (MBTS) in an amount of 1 phr to 2 phr, N-cyclohexyl-2-benzothiazyl sulfenamide (CBS) in an amount of 0.5 phr to 2 phr, and 1,3-diphenylguanidine (DPG) in an amount of 1 phr to 3 phr.

[0069] The vulcanization acceleration aid is not particularly limited and may be any vulcanization acceleration aid known to those skilled in the art. For example, the vulcanization acceleration aid may be zinc oxide (ZnO) and a fatty acid. Preferably, the vulcanization acceleration aid of the present invention is zinc oxide (ZnO) and stearic acid. The total amount of the vulcanization acceleration aid 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 is 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 can 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, which functions to bond to the silanol groups of the silica to inhibit silica aggregation and 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 phr to 20 phr, preferably 5 phr to 18 phr, more preferably 7 phr to 16 phr, for example, 9 phr to 15 phr.

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

[0072] According to a further aspect, the present invention provides a method of manufacturing a tread band, the method comprising compounding a rubber composition as described herein to form a rubber compound, forming (e.g., molding) the rubber compound into a desired shape, and vulcanizing the rubber compound. The method may further comprise forming (e.g., by cutting) one or more circumferential grooves, lateral grooves, and / or sipes to form tread features, as described below.

[0073] When preparing the tread band of the present invention, the method for combining the components in the rubber composition from which it is prepared 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 presses can be used. Mixing of the components is usually carried out in stages in which the components can be added. A multi-stage mixing process is generally preferred to optimize dispersion of the silica filler system and may include 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 prepared, followed by one or more additional non-productive mixing stages, and finally a productive mixing stage in which the curatives (i.e., sulfur or sulfur donors and accelerators) are added. Mixers that can be used are well known in the art and include, for example, open mills or Banbury-type mixers with tangential or intermeshing rotors.

[0074] Typically, the first and second elastomers, hydrocarbon polymer additive components, fillers (if present), additional processing aids (if present), zinc oxide, stearic acid, antidegradants (e.g., antioxidants, antiozonants), pigments, compatibilizers, and coupling agents (if present) are mixed to produce an initial masterbatch. This initial masterbatch may be followed by a non-productive mix stage in which no additional components are added. An optional non-productive mix stage 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. In producing the initial masterbatch, mixing can be carried out at a temperature of, for example, about 80°C to about 110°C, e.g., about 100°C. During the non-productive mix stage, the temperature can be increased, for example, to about 150°C, e.g., 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 filler is present). Mixing times may vary and can be easily determined by one 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 stage involves the addition of curatives, including accelerators and antidegradants. The temperature in this stage is generally lower, for example, in the range of about 40°C to about 60°C, e.g., about 50°C. This final mixing may be followed by a further non-productive mixing stage in which no additional ingredients are added. The most appropriate type of mixing can be readily selected to achieve a vulcanizable rubber compound. The mixing speed can be easily determined, but may range, for example, from about 20 rpm to about 100 rpm, e.g., from about 30 rpm to about 80 rpm, preferably about 50 rpm. Curing to crosslink the rubber component can be carried out by well-known methods.In the tire industry, for example, uncured rubber (so-called "green body") is produced and subsequently cured in a press mold, which simultaneously crosslinks the rubber component and shapes the component into a finished tire. Vulcanization cures the rubber by crosslinking, primarily via sulfur crosslinking. Vulcanization methods and conditions for curing rubber compositions are well known to those skilled in the art. Suitable vulcanization conditions typically include heating to a temperature ranging from 120°C to 200°C, e.g., 140°C to 180°C, for a duration of 5 to 180 minutes, e.g., 5 to 120 minutes.

[0075] Tread band features According to the present invention, the central elements are separated along their entire axial width by transverse sipes that define two endpoints at their respective axially 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 hereinabove, additional beneficial and / or synergistic effects are seen on wet performance, wear resistance, and rolling resistance, as well as the balance between these properties.

[0076] Preferably, an imaginary linear extension between the two end points defines an inclination angle of the transverse sipe relative to the axial direction of the tire, the absolute value of which is in the range of 25° to 50°, more preferably in the range of 25° to 45°, and even more preferably in the range of 30° to 40°. The absolute value may be approximately 35°. The sipes are thus positioned to improve the lateral and circumferential connection of the central element, resulting in improved cornering performance and circumferential stiffness. Furthermore, because the sipes are inclined, they move gradually and progressively into the tire's contact patch without simultaneously moving along the entire length of the sipe. This reduces noise emissions.

[0077] Preferably, the imaginary linear extensions of the transverse sipes of the two rows of central elements are inclined in opposite directions to balance the direction and magnitude of the lateral force.

[0078] Preferably, the extension of the transverse sipe along the axial direction between the two end points of the transverse sipe is non-linear, and 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 end points of the transverse sipe is substantially S-shaped. The sipes are thus arranged 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 providing a more gradual 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, resulting in a three-dimensional shape of the transverse sipe. (The wavy profile can be visible on the tread surface, or it can terminate inside the tread at a certain distance below the tread surface.) This results in a local increase in contact area, which leads to improved braking, and may also lead to localized wear reduction.

[0081] Preferably, the transverse sipes have a total length along their extension between two endpoints, and the total length of the transverse sipes having a wavy profile superimposed on the S-shaped extension is at least 20% greater than a transverse sipe extending along a straight line between the two endpoints, such that the sipes have minimal performance improvement compared to sipes that follow a straight line between the endpoints.

[0082] As the axially wavy profile extends radially (i.e., in the depth direction of the sipe), another wavy profile may be superimposed on the radial extension. In this way, the profile undulates in two directions. Therefore, as a first block moves radially, it contacts an adjacent second block on the other side of the sipe, limiting the first block's radial movement. This further enhances the above-mentioned effect of the axially wavy profile.

[0083] Preferably, each end point of the transverse sipes in each row of the central element is offset circumferentially relative to each circumferentially closest end point of the transverse sipes in one or more adjacent rows. In this manner, the end points of adjacent rows are not aligned along the tire axial direction. This results in reduced tire noise. The impacts of the different end points with the road surface are arranged so that they do not all occur simultaneously; if all the end points impact simultaneously, the result would be interference with noise generation.

[0084] Preferably, each of the end points is circumferentially offset relative to a respective circumferentially closest end point of each transverse sipe in the row.

[0085] Preferably, the transverse sipes have a radial extension inward of the tread band along a radial profile which becomes wavy or zigzag as the sipe extends axially.

[0086] Preferably, in the footprint region, 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 tire. This helps balance the stiffness of the tire's shoulders and center, avoid rib "bumps," and reduce tire wear. This arrangement can also reduce tire noise by reducing the synchronization of impacts of the center and shoulder elements with the road surface.

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

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

[0089] In one preferred form, the central elements are free of cuts and are preferably separated only by transverse sipes.

[0090] Preferably, the shoulder elements are separated by lugs extending substantially in the axial direction of the tire, the lugs having a width in the circumferential direction and having, along their longitudinal extension, a first portion intersecting the circumferential groove and a second portion extending axially outward of the tire.

[0091] Preferably, the width of the lug at the first portion intersecting the circumferential groove is smaller than the width of the lug at the second portion. This helps to reduce noise caused by the impact of the shoulder element or block on the road surface. More specifically, this helps to reduce so-called air pumping within the lug, which generates noise emissions. Tire noise can be measured using a pass-by noise test. Conversely, the fact that the lug intersects the circumferential groove means that adjacent blocks can move relative to each other as they exit the tire's 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, which helps to reduce so-called air pumping within the lug, which generates noise emissions.

[0093] The width of the first portion may be about 0.4 mm.

[0094] Preferably, the sidewalls of the first portion are configured to contact each other as the first portion passes through the tire's contact patch with the road surface. In this way, the first portion is closed when it is within the contact patch, which helps reduce noise caused by the block's 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 intersections between the lugs and the circumferential grooves are circumferentially offset relative to the circumferentially closest end points of the transverse sipes in each row of the center element, which arrangement can reduce tire noise by reducing synchronization of the center element and shoulder elements with the road surface.

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

[0097] In one preferred form, the shoulder elements are free of notches and are preferably separated only by lugs.

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

[0099] As best seen in Figure 2, the tread band 2 has two shoulder regions 10, 11 at the axially outer ends of the tread band 2 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, 11 has a shoulder (first) circumferential rib 20, 21 extending along the circumferential direction of the tire 1. Also, each of the shoulder regions 10, 11 has a row of shoulder elements or blocks 20A, 21A arranged along the shoulder circumferential rib 20, 21.

[0101] In this embodiment, the central region 15 has three central (second) circumferential ribs 25, 26, 27 that extend circumferentially around the tire 1. Also in this embodiment, the central region 15 has three rows of central elements or blocks 25A, 26A, 27A arranged along the central circumferential ribs 25, 26, 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 separating the shoulder ribs 20, 21 and the central rib 25, 26, 27 from the other circumferential ribs 20, 21, 25, 26, 27.

[0104] In the footprint region, the axial width of each of the shoulder blocks 20A, 21A is greater than the axial width of each of the central blocks 25A, 26A, 27A.

[0105] Additionally, the total number of shoulder blocks 20A, 21A in each row is greater than the total number of center blocks 25A, 26A, 27A in each row around the tire 1. This helps balance the stiffness of the tire's shoulders and center, avoiding rib "bumps" and reducing tire wear. This arrangement also reduces tire noise by reducing the synchronization of center and shoulder elements with the road.

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

[0107] The shoulder blocks 20A, 21A are separated by a lug 40 that extends substantially in the axial direction of the tire 1.

[0108] As best shown in FIG. 3 , the lug 40 has a width in the circumferential direction and, along its longitudinal extension, a first portion 40A that intersects the circumferential groove 33 and a second portion 40B that extends axially outward from the first portion 40A. The width of the lug 40 at the first portion 40A is smaller than the width of the lug 40 at the second portion 40B. In particular, the width of the first portion 40A is small enough so that the sidewalls of the first portion 40A contact each other when the first portion 40A passes through the tire's contact patch with the road surface. In this manner, the first portion 40A is closed when it is within the contact patch, which helps reduce noise generated by the impact of the blocks 20A, 21A on the road surface.

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

[0110] An imaginary straight extension 60 between the two end points defines the inclination angle θ of the transverse sipe 52 relative to the axial direction of the tire 1. The absolute value of the angle θ ranges from 25° to 50°, and in this embodiment is 35°. The sipes are thus positioned to improve the lateral and circumferential connection of the central elements, resulting in improved cornering performance and circumferential stiffness.

[0111] In Figure 3, an imaginary linear extension line 60 is shown for sipe 52 separating central blocks 27A. It can be seen that sipe 51 separating central blocks 26A is angled in the same direction as sipe 52. However, it can be seen that sipe 50 separating central blocks 25A is angled in the opposite direction to sipes 51 and 52.

[0112] The sipes 50, 51, 52 do not extend in a straight line, this is done to improve the lateral and circumferential connection of the central elements, resulting in improved cornering performance and circumferential stiffness.

[0113] The axial extension between the two end points of the transverse sipes 50, 51, 52 is substantially S-shaped in plan view. The sipes are thus arranged 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 providing a more gradual block impact with the road surface.

[0114] Furthermore, a wave-like profile (a zigzag profile in this embodiment) is superimposed on the S-shaped extension of the transverse sipes 50, 51, 52 in the axial direction in a plan view.

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

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

[0117] In this embodiment, the central blocks 25A, 26A, 27A are not notched and are separated only by transverse sipes 50, 51, 52. The central blocks 25A, 26A, 27A also have smooth radially outer surfaces.

[0118] In this embodiment, the intersections of the lugs 40 with the circumferential grooves 30, 33 are offset circumferentially relative to the circumferentially closest end points of the transverse sipes 50, 51, 52 in each row of the center blocks 25A, 26A, 27A. This arrangement can reduce tire noise by reducing the synchronization of impact between the center and shoulder blocks 25A, 26A, 27A, 20A, 21A and the road surface. Taking the lower lug 40 shown in FIG. 3 as an example, it can be seen that its intersection with the circumferential groove 33 is offset from the end point of the upper sipe 51 in block 26A. The intersections of the lower lugs 40 are also offset from the end points of the sipes 50, 52 in the other blocks 25A, 27A. In this embodiment, this is the case for at least some of the lugs 40 in the right shoulder region shown in FIG. 3. This is also the case for at least some of the lugs 40 in the left shoulder region shown in FIG. 3.

[0119] As shown in Figure 3, the lower lugs 40 extend in a substantially straight line. Furthermore, in this embodiment, although not required, the inclination angle of the lugs 40 relative to the tire axial direction is less than the inclination angle of an imaginary straight line extension between the two end points of the transverse sipes 50, 51, 52. However, it is not required that all of the lugs 40 and all of the transverse sipes 50, 51, 52 have this relationship, and it is possible that only some of the lugs 40 and the transverse sipes 50, 51, 52 have this relationship. In this embodiment, although not required, the inclination angle of the lugs 40 relative to the tire axial direction 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 required and the number of ribs, rows, and circumferential grooves may be different.

[0121] Figure 4 shows a transverse sipe forming portion 100 of a mold for tire 1. The shape of the transverse sipe forming portion 100 corresponds to the sipes to be formed, such as sipes 50, 51, and 52. As can be seen in Figure 4, as the axially oriented wavy profile extends radially (i.e., in the direction of the sipe depth), 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 have been described purely by way of example and various modifications, additions and / or omissions may be suggested to those skilled in the art, all of which form part of the present invention.

[0123] In a particular embodiment, the tread band comprises two shoulder regions at the axially outer ends of the tread band; a central region identified between the shoulder regions; a row of shoulder elements disposed along the first circumferential rib in each of the shoulder regions; at least two rows of central elements disposed along the second circumferential rib in a central region; at least three circumferential grooves separating the first and second circumferential ribs from one another; the central elements are separated along their entire axial width by transverse sipes, the transverse sipes defining two end points at their respective axially outer ends where they intersect the circumferential grooves; the axial extensions of the transverse sipes between their two end points are substantially S-shaped, a wavy profile is superimposed on the axial S-shaped extensions of the transverse sipes, the transverse sipes have total lengths along their extensions between their two end points, the total length of the transverse sipes having the wavy profile superimposed on the S-shaped extensions being at least 20% greater than the transverse sipes extending along a straight line between their two end points, the transverse sipes have radial extensions inward of the tread band along their radial profiles, the radial profile becoming wavy or zigzag as the sipes extend axially; The tread band is (i) a first hydrocarbon polymer additive that is a partially hydrogenated C5 resin; and (ii) a second hydrocarbon polymer additive that 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.

[0124] In a particular embodiment, the tread band comprises two shoulder regions at the axially outer ends of the tread band; a central region identified between the shoulder regions; a row of shoulder elements disposed along the first circumferential rib in each of the shoulder regions; at least two rows of central elements disposed along the second circumferential rib in a central region; at least three circumferential grooves separating the first and second circumferential ribs from one another; the central elements are separated along their entire axial width by transverse sipes, the transverse sipes defining two end points at their respective axially outer ends where they intersect the circumferential grooves; the axial extensions of the transverse sipes between their two end points are substantially S-shaped, a wavy profile is superimposed on the axial S-shaped extensions of the transverse sipes, the transverse sipes have total lengths along their extensions between their two end points, the total length of the transverse sipes having the wavy profile superimposed on the S-shaped extensions being at least 20% greater than the transverse sipes extending along a straight line between their two end points, the transverse sipes have radial extensions inward of the tread band along their radial profiles, the radial profile becoming wavy or zigzag as the sipes extend axially; The tread band is 1. A hydrocarbon polymer additive component comprising: (i) a first hydrocarbon polymer additive that is a partially hydrogenated C5 resin in an amount of 1 phr to 30 phr; (ii) a second hydrocarbon polymer additive which is a fully hydrogenated C9 resin in an amount of from 1 phr to 30 phr; a hydrocarbon polymer additive component, wherein 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; a first styrene butadiene copolymer functionalized with terminal carboxyl groups, the first styrene butadiene copolymer 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; Natural rubber in an amount of 10 phr to 30 phr; Its surface is functionalized with one or more carboxyl groups, present in an amount of 60 phr to 70 phr, and has a surface area of ​​240 m to 270 m 2 / g CTAB specific surface area and / or 270m-300m 2 a first silica having a BET surface area of ​​1 / g; 65m~95m 2 / g CTAB specific surface area and / or 70m to 110m 2 / g BET surface area and a second silica 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 elements may be separated by lugs extending substantially in the axial direction of the tire, the lugs having a width in the circumferential direction and having, along their longitudinal extension, a first portion intersecting the circumferential groove and a second portion extending axially outward of the tire, the width of the lug at the first portion intersecting the circumferential groove being smaller than the width of the lug at the second portion.

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

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

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

[0130] Example Measurement method Elastic modulus (E') The elastic modulus (E') is used to evaluate grip performance. Dynamic physical testing to determine E' at 30°C is performed according to ISO 4664 standard.

[0131] Loss factor (tanδ) The loss factor (tangent delta, or tan delta) at different temperatures is used to assess rolling resistance and wet traction.

[0132] Tan δ at lower temperatures is an indicator of wet traction. An increase in tan δ at lower temperatures compared to a control compound correlates with improved wet traction of the tread compound. When developing a rubber composition for a tire tread to improve the rolling resistance of the tire, the loss tangent (tan δ) around 60°C is typically considered as an indicator. By using a rubber composition with a low tan δ around 60°C as the tread rubber, tire heat generation can be suppressed, rolling resistance can be reduced, and tire fuel economy can be improved. Therefore, tan δ at 60°C is an indicator of rolling resistance (RR). A lower result compared to a control compound indicates a decrease in rolling resistance. Dynamic physical tests to determine tan δ are performed according to the ISO 4664 standard.

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

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

[0135] General method Tire compounds were prepared according to the following general method: The following ingredients were blended in the amounts set forth 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-polymerized SBR (s-SBR) (EUROPRENE® SOL RX 74618) natural rubber Emulsion-polymerized styrene-butadiene rubber (e-SBR) (EUROPRENE® 1739 BA, extended with 37.5 phr 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®) Octyl Oleate Residual Aromatic Extracted Oil (RAE) sulfur 1,3-diphenylguanidine (DPG) Dibenzothiazyl disulfide (MBTS) N-Cyclohexyl-2-benzothiazylsulfenamide (CBS) Zinc oxide (ZnO) Stearic acid.

[0137] [Table 1]

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

[0139] The compounds in Table 1 were used to prepare tire treads by extrusion molding as known to those skilled in the art. The abrasion resistance, wet performance, and rolling resistance of these tires were measured using the methods described above. The results of these measurements are shown in Table 2 for Comparative Example 1, for which all values ​​of the listed properties were normalized to 100. A value of a viscoelastic property greater than 100 indicates an improvement in that property, and a value of a property less than 100 indicates a reduction in that property.

[0140] [Table 2]

[0141] The results in Table 2 demonstrate significant improvements in performance (particularly wear resistance) when tires having the third alternative (third alternative) sipes of the present invention are prepared from compounds containing both the preferred C5 and C9 resins. As can be seen from Table 2, tires prepared from compounds containing both C5 and C9 resins but with sipes different from the third alternative do not perform as well, nor do tires prepared from compounds containing the third alternative sipes but only one of the resins. This demonstrates the synergistic improvement when C5 and C9 resins are combined with the sipes of the present invention.

Claims

1. A tread band (2) for a tire (1) suitable for engaging a road surface in a footprint area, comprising: two shoulder regions (10, 11) at the axially outer ends of the tread band (2); a central region (15) identified between said shoulder regions (10, 11); a row of shoulder elements (20A, 21A) arranged along the first circumferential rib (20, 21) in each of the shoulder regions (10, 11); at least two rows of central elements (25A, 26A, 27A) arranged along the second circumferential ribs (25, 26, 27) in the central region (15); at least three circumferential grooves (30, 31, 32, 33) separating the first circumferential rib and the second circumferential rib (20, 21, 25, 26, 27) from another circumferential rib (20, 21, 25, 26, 27); said central elements (25A, 26A, 27A) are separated along their entire axial width by transverse sipes (50, 51, 52) that define two endpoints at their respective axially outer ends where they intersect with said circumferential grooves (30, 31, 32, 33); The tread band is (i) Partially hydrogenated C ５ a first hydrocarbon polymer additive that is a resin; (ii) Hydrogenated C ５ Resin, hydrogenated C ５ / C ９ Copolymer Resin, Hydrogenated C ９ a second hydrocarbon polymer additive which is a fully hydrogenated resin selected from the group consisting of: a tread band (2), a tread band (3), a tread band (4), a tread band (5), a tread band (6), a tread band (7), a tread band (8), a tread band (9), a tread band (10), a tread band (11), a tread band (12), a tread band (13), a tread band (14), a tread band (15), a tread band (16), a tread band (17), a tread band (18), a tread band (19), a tread band (2 ...30), a tread band (31), a tread band (32), a tread band (33), a tread band (34), a

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

3. The first hydrocarbon polymer additive is a partially hydrogenated C ５ and dicyclopentadiene (DCPD) copolymer, preferably DCPD is ５ and DCPD monomer is present in an amount of less than 5% by weight.

4. The first hydrocarbon polymer additive has the following characteristics: an olefinic proton content of less than 10 mol %, preferably between 2 mol % and 8 mol %; a softening point of 110°C or higher, preferably 120°C to 140°C; a weight average molecular weight of 200 g / mol to 2000 g / mol, preferably 800 g / mol to 1400 g / mol, and / or A glass transition temperature (T) of 50°C or higher, preferably 60°C to 90°C ｇ ), partially hydrogenated C ５ A tread band (2) according to any one of claims 1 to 3, which is made of resin.

5. The second hydrocarbon polymer additive is a fully hydrogenated C ９ A tread band (2) according to any one of claims 1 to 4, which is made of resin.

6. The hydrogenation C ９ The resin has the following characteristics: A softening point of 100°C or higher, preferably 110°C to 135°C, a weight average molecular weight (Mw) of 700 g / mol to 1500 g / mol, and / or A glass transition temperature (T) of at least 50°C, preferably 60°C to 80°C ｇ 6. A tread band (2) according to any one of claims 1 to 5, comprising one or more of the following:

7. 7. A tread band (2) according to any one of claims 1 to 6, wherein the ratio of the amount of said first hydrocarbon polymer additive to said second hydrocarbon polymer additive is between 10:1 and 1:10, preferably between 5:1 and 1:5, more preferably between 2:1 and 1:2, and even more preferably 1:

1.

8. 8. The tread band (2) according to any one of claims 1 to 7, wherein an imaginary straight extension (60) between the two end points defines an inclination angle (θ) of the transverse sipes (52) relative to the axial direction of the tire (1), the absolute value of which is in the range of 25° to 50°.

9. 9. A tread band (2) according to claim 8, wherein the extension along the axial direction between the two end points of the transverse sipes (50, 51, 52) is substantially S-shaped, preferably a wavy profile is superimposed on the S-shaped extension along the axial direction of the transverse sipes (50, 51, 52), more preferably the transverse sipes (50, 51, 52) have a total length along their extension between the two end points, the total length of the transverse sipes (50, 51, 52) having a wavy profile superimposed on the S-shaped extension being at least 20% greater than that of transverse sipes extending along a straight line between the two end points.

10. 10. A tread band (2) according to any one of claims 1 to 9, wherein each end point of the transverse sipes (50, 51, 52) in each row of the central element (25A, 26A, 27A) is circumferentially offset relative to each circumferentially nearest end point of the transverse sipes (50, 51, 52) in one or more adjacent rows.

11. 11. A tread band (2) according to any one of claims 1 to 10, wherein the transverse sipes (50, 51, 52) have a radial extension inside the tread band (2) along a radial profile, the radial profile becoming wavy or zigzag as the sipes (50, 51, 52) extend in the axial direction.

12. A tread band (2) according to any one of claims 1 to 11, wherein said tread band further comprises a first elastomer component comprising one or more styrene-butadiene copolymers, preferably wherein said first elastomer component comprises a first styrene-butadiene copolymer and a second styrene-butadiene copolymer.

13. A tread band (2) according to claim 12, wherein said first styrene-butadiene copolymer is functionalized with terminal carboxyl groups.

14. The first styrene-butadiene copolymer has a glass transition temperature (T) in the range of -40°C to -15°C, preferably -30°C to -20°C. ｇ 14. A tread band (2) according to claim 12 or 13, comprising:

15. A tread band (2) according to any one of the preceding claims, wherein said tread band further comprises a second elastomeric component comprising natural rubber.

16. A tread band (2) according to any one of the preceding claims, wherein said tread band comprises a first silica functionalized with one or more carboxyl groups.

17. The first silica is 230 m to 285 m ２ 17. The tread band (2) according to claim 16, having a CTAB specific surface area of ​​1 / g.

18. The tread band comprises a second silica, preferably the second silica is 60 to 100 mm ２ 18. A tread band (2) according to any one of the preceding claims, having a CTAB specific surface area of ​​1 / g.

19. The tread band is a first styrene butadiene copolymer functionalized with terminal carboxyl groups, the first styrene butadiene copolymer 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 said second styrene butadiene copolymer and present in an amount of 20 phr to 30 phr; natural rubber in an amount of 10 phr to 30 phr; its surface functionalized with one or more carboxyl groups present in an amount of 60 phr to 70 phr, and 240 m to 270 m ２ / g CTAB specific surface area and / or 270 m to 300 m ２ a first silica having a BET surface area of ​​0.05g / g; 65m to 95m ２ / g CTAB specific surface area and / or 70 m to 110 m ２ / g and a second silica present in an amount of from 10 phr to 20 phr.

20. A pneumatic tyre (1) comprising a tread band (2) according to any one of claims 1 to 19.

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