Tire

Abstract

The present invention addresses the problem of providing a tire capable of achieving both wear resistance and workability during tire manufacturing. A solution therefor is a tire (1) provided with a pair of bead sections (3), a pair of sidewall sections (4), and a tread section (2) continuous with both sidewall sections (4), the tread section (2) being divided into at least three sections in the tire width direction by a center section (9) including a tire equatorial plane (11) and a pair of shoulder sections (10) including tread edges (12), wherein tread rubber (7) of the center section is made of a rubber composition containing at least a rubber component, a filler, and a softening agent, the rubber component includes at least one selected from styrene-butadiene rubber and butadiene rubber, the softening agent contains a resin, and the resin includes a C5-based resin and a C5-C9-based resin.

Description

tire

[0001] The present invention relates to a tire.

[0002] Conventionally, in the field of motorcycle tire treads, a tire has been developed that divides the tread into three parts in the tire width direction and uses two types of tread rubber to achieve a certain degree of compatibility between the performance required for straight-line driving and the performance required for cornering.

[0003] For example, Patent Document 1 discloses a motorcycle tire that includes a pair of bead portions, a pair of sidewall portions, and a tread portion that is continuous with both sidewall portions, and that the tread portion is divided into three portions in the tire width direction by a center portion that includes the tire equatorial plane and a pair of shoulder portions that include tread ends, in which the tread rubber of the center portion and the tread rubber of the shoulder portions both include a rubber component that includes a styrene-butadiene rubber and a modified conjugated diene polymer, and silica, and that contains 40 to 120 parts by mass of a filler per 100 parts by mass of the rubber component, and the silica content of the filler is 80% by mass or more. Patent Document 2 discloses a rubber composition for tires containing a rubber component, a filler, and a softener, wherein the rubber component contains at least one selected from styrene-butadiene rubber and butadiene rubber, the filler contains silica and carbon black, and the total content of the silica and the carbon black is 65 to 140 parts by mass per 100 parts by mass of the rubber component, the softener contains a liquid softener component and a hydrogenated resin, and the proportion of the hydrogenated resin in the total content of the softener is 40 mass% or more, and the hydrogenated resin has a softening point exceeding 110°C and a weight average molecular weight in terms of polystyrene of 200 to 1600 g / mol. The rubber composition for tires and a tire containing such a rubber composition are also disclosed.

[0004] International Publication No. 2017 / 204236 Japanese Patent Application Laid-Open No. 2022-187976

[0005] The above-mentioned Patent Document 1 aims to provide a tire having excellent wet grip performance and wear resistance of the tread, and the above-mentioned Patent Document 2 aims to provide a tire that achieves both tire grip performance and ease of manufacturing. However, tires are also required to achieve both wear resistance and ease of manufacturing, and no studies have been conducted on a tire that achieves both of these. Therefore, there is a demand for a tire that achieves both wear resistance and ease of manufacturing.

[0006] Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional technology and to provide a tire that can achieve both wear resistance and workability during tire manufacturing.

[0007] The gist of the tire of the present invention that solves the above problems is as follows.

[0008] [1] A tire comprising a pair of bead portions, a pair of sidewall portions, and a tread portion connected to both sidewall portions, the tread portion being divided into at least three portions in the tire width direction by a center portion including the tire equatorial plane and a pair of shoulder portions including tread edges, wherein the tread rubber of the center portion is made of a rubber composition including at least a rubber component, a filler, and a softener, the rubber component including at least one rubber selected from styrene-butadiene rubber and butadiene rubber, the softener including a resin, and the resin including a C5-based resin and a C5C9-based resin.

[0009] [2] The tire according to [1], wherein the filler contains 70 parts by mass or more of silica per 100 parts by mass of the rubber component.

[0010] [3] The tire according to [1] or [2], wherein the filler contains carbon black.

[0011] [4] The tire according to any one of [1] to [3], wherein the amount of the resin is 10 parts by mass or more and 25 parts by mass or less per 100 parts by mass of the rubber component.

[0012] [5] The tire according to any one of [1] to [4], wherein the softener further contains a liquid plasticizer.

[0013] [6] The tire according to any one of [1] to [5], wherein the content of the softener is 40 parts by mass or more per 100 parts by mass of the rubber component.

[0014] [7] The tire according to any one of [1] to [6], wherein the rubber component contains a styrene-butadiene rubber and a butadiene rubber.

[0015] [8] The tire according to any one of [1] to [7], wherein the ratio of the storage modulus at 60°C of the tread rubber of the center portion to the storage modulus at 60°C of the tread rubber of the shoulder portions exceeds 1.72.

[0016] [9] The tire according to any one of [1] to [8], which is for a motorcycle.

[0017] According to the present invention, it is possible to provide a tire that can achieve both wear resistance and workability during tire production.

[0018] 1 is a schematic cross-sectional view showing an example of a tire of the present invention.

[0019] The tire of the present invention will be described in detail below by way of example based on an embodiment thereof.

[0020] <Definitions> The compounds described herein may be derived in whole or in part from fossil resources, from biological resources such as plant resources, from recycled resources such as used tires, or from a mixture of two or more of fossil resources, biological resources, and recycled resources.

[0021] In the present invention, the extender oil contained in the rubber component is included in the softener.

[0022] <Tire> The tire of this embodiment includes a pair of bead portions, a pair of sidewall portions, and a tread portion connected to both sidewall portions, the tread portion being divided into at least three portions in the tire width direction by a center portion including the tire equatorial plane and a pair of shoulder portions including tread edges, wherein the tread rubber of the center portion is made of a rubber composition including at least a rubber component, a filler, and a softener, the rubber component including at least one rubber selected from styrene-butadiene rubber and butadiene rubber, the softener including a resin, the resin including a C5 resin and a C5C9 resin, and the tire achieves both wear resistance and workability during tire fabrication.

[0023] The rubber composition of the tread rubber in the center portion contains at least one rubber component selected from styrene-butadiene rubber and butadiene rubber, thereby providing sufficient fracture properties. Furthermore, the rubber composition of the tread rubber in the center portion contains a filler, thereby improving wear resistance. Furthermore, the rubber composition of the tread rubber in the center portion contains both a C5 resin and a C5C9 resin, which allows the C5 resin to function as an incompatible polymer and to migrate to the surface more easily. Therefore, the tire of this embodiment can achieve both wear resistance and ease of work during tire production.

[0024] (Tire Structure) First, the structure of the tire of this embodiment will be described with reference to Fig. 1. The tire 1 of this embodiment includes a pair of bead portions 3, a pair of sidewall portions 4, and a tread portion 2 continuous with both sidewall portions 4, and the tread portion 2 is divided into at least three portions in the tire width direction by a center portion 9 including a tire equatorial plane 11 and a pair of shoulder portions 10 including tread edges 12.

[0025] Each bead portion 3 normally has a bead core 5, and one or more carcass layers 6 are provided so as to extend in a toroidal shape between the pair of bead cores 5. The carcass layer 6 is made of a plurality of carcass cords coated with rubber.

[0026] The sidewall portion 4 extends radially outward from the bead portion 3 on the side surface of the tire to reinforce and protect the side surface.

[0027] The tread portion 2 extends across both sidewall portions 4. In the tire 1 of this embodiment, the tread portion 2 uses a divided tread divided into a center portion 9 and two shoulder portions 10 sandwiching the center portion 9. In the divided tread, the tread portion 2 is divided into at least three portions by the center portion 9 including the tire equatorial plane 11 and a pair of shoulder portions 10 including a tread edge 12. The divided tread may have an additional portion between the center portion 9 and the shoulder portions 10, or the center portion 9 may be divided into multiple portions. For example, the tread portion 2 may be divided into a first shoulder portion, a second shoulder portion, a first center portion, a second center portion, a third shoulder portion, and a fourth shoulder portion, in that order from the tread edge 12. The divided tread is preferably divided into three portions by the center portion 9 and a pair of shoulder portions 10. The tire equator is a latitude line of the tire that passes through the center of the tire in the width direction, and the surface in the tire circumferential direction that includes the tire equator is called the tire equatorial plane 11 .

[0028] More specifically, the center portion 9 has a widthwise curved length (L Ｃ ) is the maximum length of the curve length in the width direction of the entire tread surface (L Ｔ (=L ｃ +L ｓ +L ｓ The widthwise curve length (L Ｃ ) is the maximum length of the curve length in the width direction of the entire tread surface (L Ｔ ) is 30% to 60%, wear resistance can be ensured.

[0029] The widthwise curve length (L Ｓ) may be different between one shoulder portion 10 and the other shoulder portion 10, but it is usually preferable that they are the same, and the curve length in the width direction of the shoulder portion 10 (one side) is L Ｔ It is preferable that the value is (100-Lc) / 2%.

[0030] Hereinafter, the rubber constituting the tread portion 2 may be referred to as tread rubber. The tread rubber 8 in the shoulder portion is the rubber constituting the shoulder portion and may be simply referred to as "shoulder rubber." The tread rubber 7 in the center portion is the rubber constituting the center portion and may be simply referred to as "center rubber."

[0031] (Tread Rubber) In the tire of this embodiment, the tread rubber in the center portion is made of a rubber composition containing at least a rubber component, a filler, and a softener.

[0032] In the tire of this embodiment, the storage modulus of the tread rubber in the center portion at 60°C is preferably 12 MPa or more, more preferably 13 MPa or more, from the viewpoint of abrasion resistance, and is preferably 15 MPa or less, more preferably 14 MPa or less, from the viewpoint of steering stability.

[0033] In the tire of this embodiment, the storage modulus of the tread rubber in the shoulder portion at 60°C is preferably 5.0 MPa or more, more preferably 7.0 MPa or more, from the viewpoint of abrasion resistance, and is preferably 10 MPa or less, more preferably 8.0 MPa or less, from the viewpoint of handling stability.

[0034] The storage modulus of the center tread rubber and the shoulder tread rubber at 60°C can be measured using a viscoelasticity measuring device under conditions of 60°C, strain of 1.0%, and frequency of 52 Hz.

[0035] In the tire of this embodiment, the ratio of the storage modulus of the center portion tread rubber at 60°C to the storage modulus of the tread rubber of the shoulder portions at 60°C (storage modulus of tread rubber of center portion / storage modulus of tread rubber of shoulder portions) preferably exceeds 1.72. When the ratio of the storage modulus of the center portion tread rubber at 60°C to the storage modulus of the tread rubber of the shoulder portions at 60°C exceeds 1.72, the tire achieves both high levels of wear resistance and workability. From the same viewpoint, the ratio of the storage modulus of the center portion tread rubber at 60°C to the storage modulus of the tread rubber of the shoulder portions at 60°C is more preferably 1.75 or greater, and even more preferably 1.8 or greater.

[0036] (Rubber Composition) In the tire of this embodiment, the rubber composition constituting the tread rubber of the center portion contains at least a rubber component, a filler, and a softener, wherein the rubber component contains at least one selected from styrene-butadiene rubber and butadiene rubber, and the softener contains a resin, and the resin contains a C5 resin and a C5C9 resin. Each component contained in the rubber composition will be described below.

[0037] [Rubber Component] In the tread rubber of the center portion, the rubber component contains at least one selected from styrene-butadiene rubber (SBR) and butadiene rubber (BR). The rubber component preferably contains both styrene-butadiene rubber and butadiene rubber. Styrene-butadiene rubber and butadiene rubber are relatively difficult to adhere to each other and have excellent fracture properties.

[0038] The rubber component may be unmodified or modified, or may be a blend of unmodified and modified rubbers.

[0039] In the rubber component, the total proportion of styrene-butadiene rubber (SBR) and butadiene rubber (BR) is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, and may be 100% by mass.

[0040] -Styrene-butadiene rubber- The rubber component preferably contains styrene-butadiene rubber (SBR). From the viewpoint of improving handling stability, the rubber component preferably contains 50 parts by mass or more of the styrene-butadiene rubber per 100 parts by mass of the rubber component, more preferably 60 parts by mass or more, and even more preferably 65 parts by mass or more. Furthermore, from the viewpoint of improving abrasion resistance, the rubber component preferably contains 90 parts by mass or less of the styrene-butadiene rubber per 100 parts by mass of the rubber component, more preferably 80 parts by mass or less, and even more preferably 70 parts by mass or less.

[0041] The styrene-butadiene rubber preferably has a styrene content of 5 to 50% by mass, more preferably 8 to 45% by mass. If the styrene content of the styrene-butadiene rubber is 5% by mass or more, the abrasion resistance of the rubber composition is further improved. The styrene unit can be determined by an infrared method (Morello method).

[0042] -Butadiene Rubber- From the viewpoint of improving abrasion resistance, the rubber component preferably contains 10 parts by mass or more, more preferably 20 parts by mass or more, and even more preferably 30 parts by mass or more of butadiene rubber per 100 parts by mass of the rubber component. Furthermore, from the viewpoint of improving handling stability, the rubber component preferably contains 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 35 parts by mass or less of styrene-butadiene rubber per 100 parts by mass of the rubber component.

[0043] -Other Rubber- The rubber component may contain other rubbers in addition to styrene-butadiene rubber and butadiene rubber. The content of other rubbers in the rubber component is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 10% by mass or less, and may even be 0% by mass. Examples of such other rubbers include natural rubber (NR), isoprene rubber (IR), chloroprene rubber (CR), styrene-isoprene rubber (SIR), acrylonitrile-butadiene rubber (NBR), butyl rubber (IIR), and halogenated butyl rubber. These other rubbers may be used alone or in combination of two or more.

[0044] The rubber component may be partially or entirely oil-extended. When the rubber component is oil-extended, the extender oil is classified as a softener, which will be described later, and the amount of the extender oil is included as part of the amount of the softener.

[0045] [Filler] The rubber composition constituting the tread rubber of the center portion contains a filler. The filler preferably contains at least one selected from silica and carbon black, and more preferably contains both silica and carbon black. The filler can reinforce the rubber composition and improve the fracture properties of the rubber composition. The filler may also contain fillers other than silica and carbon black.

[0046] Silica: The filler preferably contains silica, which contributes to improving the abrasion resistance of the tire.

[0047] Silica has a nitrogen adsorption specific surface area (BET method) of 80m ２ / g or more 330m ２ The nitrogen adsorption specific surface area (BET method) of silica is preferably less than 80 m ２ / g or more 330m ２ From the viewpoint of further improving the fracture properties of the tire, the nitrogen adsorption specific surface area (BET method) of the silica is 100 m ２ / g or more is more preferable, and 120m ２ / g or more, and 140m ２ / g or more is more preferable, and 150m ２ / g or more is more preferable, and 170m ２ / g or more is more preferable, and 180m ２ / g or more is more preferable, and 190m ２ / g or more, and 195m ２ From the viewpoint of achieving both abrasion resistance and workability during tire production, the nitrogen adsorption specific surface area (BET method) of silica is preferably 300 m ２ / g or less is more preferable, and 280m ２ / g or less, and more preferably 270m２ The nitrogen adsorption specific surface area of ​​silica can be measured by a single point value according to the BET method specified by the method in accordance with ISO 5794 / 1.

[0048] The silica preferably has a cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of 150 m ２ / g or more, more preferably 150 to 300m ２ / g, and even more preferably 150 to 250 m ２ / g, particularly preferably 150 to 220 m ２ / g. CTAB is 150m ２ When the CTAB is 300 m / g or more, a tire to which the rubber composition is applied can be sufficiently reinforced. ２ When the cetyltrimethylammonium bromide adsorption specific surface area (CTAB) is 0.01 / g or less, the workability is less likely to decrease. The cetyltrimethylammonium bromide adsorption specific surface area (CTAB) can be measured in accordance with ASTM D3765-92.

[0049] Examples of silica include wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), calcium silicate, and aluminum silicate, and among these, wet silica is preferred. These silicas may be used alone or in combination of two or more.

[0050] From the viewpoint of improving abrasion resistance, the content of silica in the rubber composition is preferably 70 parts by mass or more, more preferably 75 parts by mass or more, and even more preferably 80 parts by mass or more, per 100 parts by mass of the rubber component. Also, from the viewpoint of achieving both abrasion resistance and workability during tire production, the content of silica in the rubber composition is preferably 110 parts by mass or less, more preferably 100 parts by mass or less, per 100 parts by mass of the rubber component.

[0051] Carbon Black The rubber composition preferably contains carbon black, which reinforces the rubber composition and can improve the fracture properties of the rubber composition, thereby improving the fracture properties of the tire.

[0052] The carbon black is not particularly limited, and examples thereof include GPF, FEF, HAF, ISAF, and SAF grade carbon black. These carbon blacks may be used alone or in combination of two or more.

[0053] From the viewpoints of the fracture properties of the rubber composition and the abrasion resistance of the tire, the content of carbon black in the rubber composition is preferably more than 0 part by mass, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of the rubber component. Furthermore, from the viewpoint of achieving both abrasion resistance and workability, the content of carbon black in the rubber composition is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less, per 100 parts by mass of the rubber component.

[0054] The nitrogen adsorption specific surface area of ​​carbon black (N ２ SA) is not particularly limited and can be selected appropriately depending on the purpose, but ２ / g or more. ２ SA) is 70m ２ / g or more, the abrasion resistance can be improved satisfactorily. ２ SA) can be measured in accordance with JIS K 6217-2:2001.

[0055] When the rubber composition of this embodiment contains both silica and carbon black, the ratio of silica to the total content of silica and carbon black is preferably 50% by mass or more and 95% by mass or less, more preferably 70% by mass or more, and more preferably 90% by mass or less.

[0056] Other Fillers In addition to carbon black and silica, the filler may include other fillers such as clay, talc, calcium carbonate, aluminum hydroxide, etc. The amount of these other fillers can be changed as appropriate within a range that does not impair the effects of the present invention.

[0057] [Softener] In the tire of this embodiment, the rubber composition contains a softener. The softener contains a resin, and the resin contains a C5 resin and a C5C9 resin. The softener is a compounding agent that has the effect of softening the rubber composition, and specific examples include a resin and a liquid plasticizer.

[0058] In the rubber composition, the content of the softener is preferably 40 parts by mass or more per 100 parts by mass of the rubber component. When the content of the softener is 40 parts by mass or more per 100 parts by mass of the rubber component, both abrasion resistance and workability during tire production can be more highly achieved. From the same viewpoint, the content of the softener is more preferably 45 parts by mass or more per 100 parts by mass of the rubber component. Furthermore, from the viewpoint of suppressing a decrease in abrasion resistance, the content of the softener is preferably 60 parts by mass or less, more preferably 50 parts by mass or less per 100 parts by mass of the rubber component. In the present invention, the content of the softener includes not only the content of the softener blended together with the rubber component but also the content of the extender oil previously blended in the rubber component.

[0059] Resin In the rubber composition, the resin includes a C5 resin and a C5C9 resin. By including both a C5 resin and a C5C9 resin, the tire can achieve both wear resistance and workability.

[0060] The amount of the resin is preferably 10 parts by mass or more and 25 parts by mass or less per 100 parts by mass of the rubber component. From the viewpoint of achieving both wear resistance and workability of the tire, the amount of the resin is preferably 15 parts by mass or more and more preferably 20 parts by mass or less per 100 parts by mass of the rubber component.

[0061] The C5 resin refers to a C5 synthetic petroleum resin, and examples of the C5 resin include a C5 fraction obtained by thermal cracking of naphtha in the petrochemical industry, which is decomposed into AlCl ３ , B.F. ３Examples of the C5 resin include aliphatic petroleum resins obtained by polymerization using a Friedel-Crafts catalyst such as Benzene, Ethylenediaminetetraacetic acid, or the like. The C5 fraction typically includes 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. Commercially available C5 resins can be used, including, for example, the "ESCOLETZ (registered trademark) 1000 series" aliphatic petroleum resins manufactured by ExxonMobil Chemical Corporation, the "Quinton (registered trademark) 100 series" aliphatic petroleum resins "A100, B170, M100, R100" of the "Quinton (registered trademark) 100 series" manufactured by Nippon Zeon Corporation, and "T-REZ RA100" manufactured by Tonen Chemical Industry Co., Ltd.

[0062] The C5C9 resin refers to a C5C9 synthetic petroleum resin. For example, a C5 fraction and a C9 fraction derived from petroleum are mixed with AlCl ３ , B.F. ３ Examples of suitable C5C9 resins include solid polymers obtained by polymerization using a Friedel-Crafts catalyst such as styrene, vinyl toluene, α-methyl styrene, indene, etc., and more specifically, copolymers primarily composed of styrene, vinyl toluene, α-methyl styrene, indene, etc. As the C5C9 resin, a resin with a low content of C9 or higher components is preferred from the viewpoint of compatibility with the rubber component. Here, "low content of C9 or higher components" refers to a resin in which the content of C9 or higher components in the total amount of resin is less than 50% by mass, preferably 40% by mass or less. As the C5C9 resin, commercially available products can be used, such as those sold under the trade name "Quinton (registered trademark) G100B" (manufactured by Zeon Corporation), the trade name "ECR213" (manufactured by ExxonMobil Chemical Corporation), and the trade name "T-REZ RD104" (manufactured by Tonen Chemical Industry Co., Ltd.).

[0063] In the rubber composition, the ratio of the content of the C5-based resin to the content of the C5C9-based resin is preferably 0.1 or more and 1.0 or less. When the ratio of the content of the C5-based resin to the content of the C5C9-based resin is 0.1 or more and 1.0 or less, excellent workability is achieved. From the viewpoint of workability, the ratio of the content of the C5-based resin to the content of the C5C9-based resin is more preferably 0.3 or more, even more preferably 0.5 or more, and more preferably 0.7 or less, even more preferably 0.6 or less.

[0064] The resin may contain other resins in addition to the C5 resin and the C5C9 resin, such as a C9 resin, a dicyclopentadiene resin, a terpene phenol resin, a terpene resin, a rosin resin, and an alkylphenol resin.

[0065] C9 resins are resins obtained by polymerizing aromatic compounds having 9 carbon atoms, with vinyltoluene, alkylstyrene, and indene as the main monomers. These C9 fractions are by-produced along with petrochemical base materials such as ethylene and propylene during the thermal decomposition of naphtha in the petrochemical industry. Specific examples of C9 fractions obtained by thermal decomposition of naphtha include vinyltoluene, α-methylstyrene, β-methylstyrene, γ-methylstyrene, o-methylstyrene, p-methylstyrene, and indene. The C9 resins can be obtained by copolymerizing the C8 to C10 fractions as a mixture using, for example, a Friedel-Crafts catalyst, together with the C9 fraction, C8 fractions such as styrene, C10 fractions such as methylindene and 1,3-dimethylstyrene, and even naphthalene, vinylnaphthalene, vinylanthracene, and p-tert-butylstyrene. The C9 resins may also be modified petroleum resins modified with compounds having hydroxyl groups, unsaturated carboxylic acid compounds, and the like. Commercially available products can be used as the C9 resin. Examples of unmodified C9 petroleum resins include those with the trade names "Nippon Oil Neopolymer (registered trademark) L-90," "Nippon Oil Neopolymer (registered trademark) 120," "Nippon Oil Neopolymer (registered trademark) 130," and "Nippon Oil Neopolymer (registered trademark) 140" (manufactured by JX Nippon Oil & Energy Corporation).

[0066] The dicyclopentadiene resin is a petroleum resin produced primarily from dicyclopentadiene obtained by dimerizing cyclopentadiene. Commercially available dicyclopentadiene resins can be used, such as alicyclic petroleum resins manufactured by Zeon Corporation under the trade name Quinton (registered trademark) 1000 Series (product numbers 1105, 1325, and 1340).

[0067] Terpene phenolic resins can be obtained, for example, by reacting terpenes with various phenols using a Friedel-Crafts catalyst, or by further condensing them with formalin. There are no particular limitations on the terpenes used as raw materials; monoterpene hydrocarbons such as α-pinene and limonene are preferred, with those containing α-pinene being more preferred, and α-pinene being particularly preferred. Commercially available terpene phenolic resins are available, including those sold under the trade names "Tamanol 803L" and "Tamanol 901" (manufactured by Arakawa Chemical Industries, Ltd.), and the trade names "YS Polystar (registered trademark) U" series, "YS Polystar (registered trademark) T" series, "YS Polystar (registered trademark) S" series, "YS Polystar (registered trademark) G" series, "YS Polystar (registered trademark) N" series, "YS Polystar (registered trademark) K" series, and "YS Polystar (registered trademark) TH" series (manufactured by Yasuhara Chemical Co., Ltd.).

[0068] Terpene resins are solid resins obtained by blending turpentine oil, which is obtained simultaneously when rosin is obtained from pine trees, or a polymerization component separated from this, and polymerizing the blend using a Friedel-Crafts catalyst, and examples of such resins include β-pinene resin and α-pinene resin. Commercially available terpene resins can be used, and examples include products sold under the trade name "YS Resin" series (PX-1250, TR-105, etc.) manufactured by Yasuhara Chemical Co., Ltd. and products sold under the trade name "Picolite" series (A115, S115, etc.) manufactured by Hercules.

[0069] Rosin resin is the residue remaining after collecting balsams such as pine resin (pine tar), which is the sap of plants in the Pinaceae family, and distilling turpentine essential oil. It includes natural resins whose main component is rosin acid (abietic acid, palustric acid, isopimaric acid, etc.), as well as modified and hydrogenated resins obtained by modifying, hydrogenating, or otherwise processing these. Examples include natural resin rosin, its polymerized rosin, and partially hydrogenated rosin; glycerin ester rosin, its partially hydrogenated rosin, fully hydrogenated rosin, and polymerized rosin; pentaerythritol ester rosin, its partially hydrogenated rosin, and polymerized rosin. Natural resin rosins include gum rosin, tall oil rosin, and wood rosin, which are contained in raw pine tar and tall oil. As the rosin resin, commercially available products can be used, and examples thereof include those under the trade name "Neotol 105" (manufactured by Harima Chemical Co., Ltd.), those under the trade name "SN Tack 754" (manufactured by San Nopco Ltd.), those under the trade name "Lime Resin No. 1," "Pensel A" and "Pensel AD" (manufactured by Arakawa Chemical Industries, Ltd.), those under the trade name "Polypale" and "Pentalin C" (manufactured by Eastman Chemical Co., Ltd.), and those under the trade name "Hirosin (registered trademark) S" (manufactured by Taishamatsu Oil Co., Ltd.).

[0070] The alkylphenol resin can be obtained, for example, by a condensation reaction of an alkylphenol and formaldehyde in the presence of a catalyst. Commercially available alkylphenol resins include those sold under the trade name "Hitanol 1502P" (an alkylphenol formaldehyde resin, manufactured by Hitachi Chemical Co., Ltd.), "Tackirol 201" (an alkylphenol formaldehyde resin, manufactured by Taoka Chemical Co., Ltd.), "Tackirol 250-I" (a brominated alkylphenol formaldehyde resin, manufactured by Taoka Chemical Co., Ltd.), "Tackirol 250-III" (a brominated alkylphenol formaldehyde resin, manufactured by Taoka Chemical Co., Ltd.), and "R7521P," "SP1068," "R7510PJ," "R7572P," and "R7578P" (manufactured by SI GROUP INC.).

[0071] The resin contained in the rubber composition may be hydrogenated.

[0072] Liquid Plasticizer: The softener preferably further contains a liquid plasticizer. When the rubber composition contains a liquid plasticizer, workability during tire production can be improved. The liquid plasticizer is liquid at 25°C (room temperature).

[0073] Examples of liquid plasticizers include oils. Examples of such oils include, but are not limited to, petroleum-based softeners such as aromatic oils, paraffinic oils, and naphthenic oils; and plant-based softeners such as palm oil, castor oil, cottonseed oil, and soybean oil. Among these, petroleum-based softeners such as aromatic oils, paraffinic oils, and naphthenic oils are preferred.

[0074] The content of the liquid plasticizer is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 8 parts by mass or more, per 100 parts by mass of the rubber component from the viewpoint of improving workability during tire production. Moreover, the content of the liquid plasticizer is preferably 10 parts by mass or less, per 100 parts by mass of the rubber component from the viewpoint of suppressing a decrease in abrasion resistance.

[0075] [Other Components] In addition to the rubber component, filler, and softener described above, the rubber composition may contain compounding agents commonly used in the rubber industry, such as silane coupling agents, stearic acid, antioxidants, zinc oxide (zinc white), vulcanization accelerators, and vulcanizing agents, selected appropriately within the scope that does not impair the object of the present invention.

[0076] Examples of the silane coupling agent include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl-N ,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropyl benzothiazolyl tetrasulfide, 3-triethoxysilylpropyl benzothiazolyl tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, bis(3-diethoxymethylsilylpropyl)tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, dimethoxymethylsilylpropyl benzothiazolyl tetrasulfide, etc. The content of the silane coupling agent is preferably in the range of 2 to 20 parts by mass, more preferably in the range of 5 to 15 parts by mass, per 100 parts by mass of silica.

[0077] Examples of the antioxidant include N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6C), 2,2,4-trimethyl-1,2-dihydroquinoline polymer (TMDQ), 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline (AW), N,N'-diphenyl-p-phenylenediamine (DPPD), etc. The content of the antioxidant is not particularly limited, but is preferably in the range of 0.1 to 15 parts by mass, and more preferably in the range of 1 to 10 parts by mass, per 100 parts by mass of the rubber component.

[0078] Examples of the vulcanization accelerator include sulfenamide-based vulcanization accelerators, guanidine-based vulcanization accelerators, thiazole-based vulcanization accelerators, thiuram-based vulcanization accelerators, and dithiocarbamate-based vulcanization accelerators. Examples of the vulcanizing agent include sulfur. The total content of the vulcanization system (vulcanization package) containing the vulcanization accelerator, vulcanizing agent, and stearic acid is not particularly limited, and is preferably in the range of 1 to 25 parts by mass, and more preferably 5 to 20 parts by mass, per 100 parts by mass of the rubber component.

[0079] (Other Constituent Parts) So far, the rubber composition in the tread rubber of the center portion has been described, but the component compositions of other rubber compositions such as the rubber composition in the shoulder portion constituting the tread rubber (shoulder rubber) in the shoulder portion and the rubber compositions constituting other tire parts are not particularly limited.

[0080] The other rubber composition may contain the rubber component, filler, softener, and silane coupling agent that may be contained in the rubber composition in the tread rubber of the center portion, and may also contain stearic acid, an antioxidant, zinc oxide (zinc white), a vulcanization accelerator, a vulcanizing agent, etc.

[0081] From the viewpoint of grip, it is preferable that the total amount of softener in the rubber composition of the tread rubber of the shoulder portion is greater than the total amount of softener in the rubber composition of the tread rubber of the center portion.

[0082] (Method for manufacturing a tire) The tire of this embodiment is obtained by molding and vulcanizing a rubber composition. The method for manufacturing the rubber composition is not particularly limited, but for example, the tire can be manufactured by blending the above-mentioned rubber component, filler, and softener with various components appropriately selected as necessary, and kneading, heating, extruding, etc. Furthermore, the obtained rubber composition can be vulcanized to form a vulcanized rubber.

[0083] The kneading conditions are not particularly limited, and various conditions such as the input volume of the kneading device, the rotation speed of the rotor, the ram pressure, the kneading temperature, the kneading time, the type of kneading device, etc. can be appropriately selected depending on the purpose. Examples of the kneading device include a Banbury mixer, an intermix, a kneader, a roll, etc., which are usually used for kneading rubber compositions.

[0084] The conditions for the heat-in are not particularly limited, and various conditions such as the heat-in temperature, heat-in time, and heat-in device can be appropriately selected depending on the purpose. Examples of the heat-in device include a heat-in roll mill typically used for heat-in of rubber compositions.

[0085] The extrusion conditions are not particularly limited, and various conditions such as extrusion time, extrusion speed, extrusion device, and extrusion temperature can be appropriately selected depending on the purpose. Examples of the extrusion device include an extruder typically used for extruding rubber compositions. The extrusion temperature can be appropriately determined.

[0086] The vulcanization equipment, method, conditions, etc. are not particularly limited and can be appropriately selected depending on the purpose. Examples of equipment for vulcanization include a molding vulcanizer using a mold used for vulcanizing rubber compositions. The vulcanization temperature is, for example, about 100 to 190°C.

[0087] The tire of this embodiment may be obtained by molding an unvulcanized rubber composition and then vulcanizing it, depending on the type of tire to be applied, or by molding a semi-vulcanized rubber that has been subjected to a pre-vulcanization step and then further vulcanizing it. The tire of this embodiment is preferably a pneumatic tire, and the gas to be filled into the pneumatic tire may be normal air or air with an adjusted oxygen partial pressure, or an inert gas such as nitrogen, argon, or helium.

[0088] (Applications) The tire of this embodiment can be used for various purposes, including but not limited to motorcycles and four-wheeled vehicles. However, the effects of the present invention are particularly easily realized when used for motorcycles. When used as a motorcycle tire, it may be a front tire or a rear tire. However, in the present invention, high levels of wear resistance and workability during tire manufacturing can be achieved, so the effects of the present invention are particularly easily realized when applied to a rear tire. The type of motorcycle is not particularly limited and can be appropriately selected depending on the purpose. Examples of types of motorcycles include racing motorcycles, motorcycles for general public roads, motorcycles for on-road use, and motorcycles for off-road use. Among these, motorcycles for which the effects of the present invention are particularly easily realized are preferred for general public roads and motorcycles for on-road use, and more preferably for general public roads.

[0089] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples in any way.

[0090] <Preparation of Rubber Composition for Tread Rubber of Shoulder Portion> A rubber composition for the tread rubber of the shoulder portion (rubber composition for shoulder rubber) was prepared using a normal Banbury mixer according to the compounding recipe shown in Table 1. Note that the "total amount of softener" in Table 1 means the total amount of the softener as a compounding component and the oil-extended amount of the rubber component.

[0091] [Measurement of Rubber Composition in Tread Rubber of Shoulder Portion] -Storage Modulus- The storage modulus of the rubber composition in the tread rubber of the shoulder portion was measured using a viscoelasticity measuring device (manufactured by Ueshima Seisakusho Co., Ltd.) at a temperature of 60°C, a frequency of 52 Hz, and a strain of 1.0%. The measurement results are shown in Table 1.

[0092]

[0093] *1 SBR: Styrene-butadiene rubber, manufactured by ENEOS Materials Corporation, emulsion-polymerized styrene-butadiene rubber, product name "HP755B", containing 37.5 parts by mass of extender oil per 100 parts by mass of rubber component. The middle row shows the rubber component content, and the bottom row shows the extender oil content. *2 BR: Butadiene rubber, manufactured by ENEOS Materials Corporation, trade name "BR01" *3 Carbon black, manufactured by Asahi Carbon Co., Ltd., trade name "ASAHI #107" *4 Silica: Manufactured by Tosoh Silica Corporation, trade name "Nipsil AQ" *5 Oil: Manufactured by JX Nippon Oil & Energy Corporation, trade name "A / O MIX" *6 C5C9 resin: Manufactured by ENEOS Corporation, trade name "T-REZ RD104" *7 Coupling agent: Manufactured by Shin-Etsu Chemical Co., Ltd., trade name "ABC-856" *8 Other chemicals: Total amount including wax, antioxidant and workability improver *9 Vulcanization package: Total amount including vulcanization accelerator, sulfur and stearic acid

[0094] <Preparation of Rubber Composition for Tread Rubber of Center Portion> Rubber compositions for the tread rubber of the center portion (rubber compositions for center rubber) of Example 1 and Comparative Examples 1 to 3 were prepared using a normal Banbury mixer according to the compounding recipes shown in Table 2. Table 2 shows the compounding and evaluation results. Note that the "total amount of softener" in Table 2 means the total amount of the softener as a compounding component and the oil-extended amount of the rubber component.

[0095] [Measurement of Rubber Composition in Tread Rubber of Center Portion] -Storage Modulus- The storage modulus of the rubber composition in the tread rubber of the center portion was measured using a viscoelasticity measuring device (manufactured by Ueshima Seisakusho Co., Ltd.) at a temperature of 60°C, a frequency of 52 Hz, and a strain of 1.0%. In addition, from the measurement results of the storage modulus of the rubber composition in the tread rubber of the shoulder portions and the rubber composition in the tread rubber of the center portion, the ratio of the storage modulus of the tread rubber of the center portion at 60°C to the storage modulus of the tread rubber of the shoulder portions at 60°C (storage modulus (center portion) / storage modulus (shoulder portion)) was calculated. The measurement results and calculation results are shown in Table 2.

[0096] <Production of Tire> Using each of the prepared rubber compositions, motorcycle tires (size: 180 / 55ZR17) were produced in a conventional manner, each of which had a pair of bead portions, a pair of sidewall portions, and a tread portion continuous with both sidewall portions, the tread portion being divided into three portions in the tire width direction by a center portion including the tire equatorial plane and a pair of shoulder portions including the tread ends.

[0097] <Evaluation> Workability during tire production and abrasion resistance were evaluated by the following methods.

[0098] (1) Workability The adhesion between the unvulcanized rubber composition and metal at 90°C was measured using a tack meter and expressed as an index, with the reciprocal of the adhesion of Comparative Example 1 being set to 100. Note that a larger index indicates a smaller adhesion and better workability.

[0099] (2) Wear Resistance A test rider drove the vehicle 3,500 km at 80 km / h on a paved test course. After the run, the remaining groove depth was measured, and the wear resistance of the tire was evaluated based on the remaining groove depth. The evaluation result of Comparative Example 1 was expressed as an index, with 100 being the result. The larger the index, the better the wear resistance.

[0100]

[0101] *10 C5 resin: Manufactured by ENEOS, product name “T-REZ RA100”

[0102] From Table 2, it can be seen that the tire of this embodiment is able to achieve both workability and wear resistance.

[0103] According to the present invention, it is possible to provide a tire that can achieve both high wear resistance and workability during tire production.

[0104] 1: Tire 2: Tread portion 3: Bead portion 4: Sidewall portion 5: Bead core 6: Carcass layer 7: Tread rubber in center portion 8: Tread rubber in shoulder portion 9: Center portion 10: Shoulder portion 11: Equatorial plane 12: Tread edge

Claims

1. A tire comprising a pair of bead portions, a pair of sidewall portions, and a tread portion connected to both sidewall portions, the tread portion being divided into at least three portions in the tire width direction by a center portion including the tire equatorial plane and a pair of shoulder portions including the tread edges, wherein the tread rubber of the center portion is made of a rubber composition including at least a rubber component, a filler, and a softener, the rubber component including at least one rubber selected from styrene-butadiene rubber and butadiene rubber, and the softener includes a resin, the resin including a C5 resin and a C5C9 resin.

2. The tire according to claim 1, wherein the filler contains 70 parts by mass or more of silica per 100 parts by mass of the rubber component.

3. The tire of claim 1, wherein said filler comprises carbon black.

4. The tire according to claim 1, wherein the content of the resin is 10 parts by mass or more and 25 parts by mass or less per 100 parts by mass of the rubber component.

5. The tire of claim 1, wherein said softener further comprises a liquid plasticizer.

6. The tire according to claim 1, wherein the content of the softener is 40 parts by mass or more per 100 parts by mass of the rubber component.

7. The tire of claim 1, wherein the rubber component comprises styrene-butadiene rubber and butadiene rubber.

8. The tire according to claim 1, wherein the ratio of the storage modulus at 60°C of the tread rubber of the center portion to the storage modulus at 60°C of the tread rubber of the shoulder portions exceeds 1.

72.

9. The tire according to claim 1, which is for a motorcycle.

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