Rubber composition and tire

Abstract

To provide a rubber composition that achieves improved overall performances including dry grip performance, wet grip performance and fuel economy, and a tire including the same.SOLUTION: A rubber composition contains modified rubber having at least one selected from the group consisting of carboxylic acid, sulfonic acid, and salts thereof in each molecule, and at least one metal oxide selected from the group consisting of lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, beryllium oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide and the like. The action of water causes a reversible change in complex elastic modulus (E*) and loss tangent (tanδ). The rubber composition satisfies the following formula (1) and / or the following formula (2). E* under water-wet condition / E* under dry condition≤0.90 (1) and tanδ under water-wet condition / tanδ under dry condition≥1.10 (2).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to rubber compositions and tires. [Background technology]

[0002] The grip performance of a tire is important because it is directly linked to safety, and various studies have been conducted to improve the grip performance (see, for example, Patent Document 1). Furthermore, from an environmental perspective, fuel economy is also important, and further improvements in grip performance (dry grip performance and wet grip performance) and fuel economy are required. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-285524 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure aims to solve the above problems and provide a rubber composition that improves the overall performance of dry grip performance, wet grip performance, and fuel economy, and a tire using the same. [Means for solving the problem]

[0005] The present disclosure provides a modified rubber having at least one selected from the group consisting of carboxylic acids, sulfonic acids, and salts thereof in the molecule; at least one metal oxide selected from the group consisting of lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, beryllium oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, scandium oxide, titanium oxide, vanadium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide, yttrium oxide, zirconium oxide, niobium oxide, molybdenum oxide, technetium oxide, ruthenium oxide, rhodium oxide, palladium oxide, silver oxide, hafnium oxide, tantalum oxide, tungsten oxide, osmium oxide, iridium oxide, platinum oxide, gold oxide, aluminum oxide, gallium oxide, cadmium oxide, indium oxide, tin oxide, thallium oxide, lead oxide, bismuth oxide, and polonium oxide; The rubber composition has a complex modulus (E*) and a loss tangent (tan δ) that are reversibly changed by water and that satisfies the following formula (1) and / or formula (2): E* when wet / E* when dry≦0.90 (1) Tan δ when wet / tan δ when dry ≧ 1.10 (2) (In the formula, E* and tanδ are the complex modulus and loss tangent measured 30 minutes after the start of measurement under the following conditions: temperature 30°C, initial strain 10%, dynamic strain 1%, frequency 10 Hz, extension mode, and measurement time 30 minutes.) [Effects of the Invention]

[0006] According to the present disclosure, the rubber composition contains the modified rubber having carboxylic acid or the like in the molecule and a metal oxide such as lithium oxide, and satisfies the formula (1) and / or (2), thereby improving the overall performance of dry grip performance, wet grip performance, and fuel economy. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a cross-sectional view showing a portion of a pneumatic tire. DETAILED DESCRIPTION OF THE INVENTION

[0008] <Rubber composition> The present disclosure provides a rubber composition that contains a modified rubber having at least one selected from the group consisting of carboxylic acid, sulfonic acid, and salts thereof in the molecule, and the metal oxide, and satisfies formulas (1) and / or (2). The rubber composition exhibits improved overall performance in terms of dry grip performance, wet grip performance, and fuel economy.

[0009] The reason why the rubber composition exhibits the above-mentioned effects is not entirely clear, but it is presumed to be due to the following mechanism. When a modified rubber containing carboxylic acid or the like in its molecule is combined with the metal oxide, an ionic bond is formed between the carboxylic acid or the like and the metal of the metal oxide. While this ionic bond is formed when the rubber is dry, the ionic bond dissociates when the rubber is wet (when the rubber comes into contact with water), resulting in a decrease in E* and / or an increase in tan δ of the rubber composition. Therefore, when the rubber is wet (when the rubber comes into contact with water), the contact area with the road surface increases and / or energy loss increases, improving friction (μ) on wet roads and improving wet grip performance. Furthermore, because the dissociation and bonding of the ionic bond is reversible, ionic bonding occurs again when the rubber dries, restoring E* and / or tan δ. This means that wet grip performance can be improved while maintaining good friction (μ) and fuel economy when driving on dry roads. Therefore, it is believed that the rubber composition improves overall performance in terms of dry grip performance, wet grip performance, and fuel economy.

[0010] Thus, the present disclosure solves the problem (objective) of improving the overall performance of dry grip performance, wet grip performance, and fuel economy by configuring a rubber composition that contains a modified rubber having a carboxylic acid or the like in the molecule and the metal oxide, and that satisfies the parameters of the above formulas (1) and / or (2). In other words, the parameters do not define the problem (objective), and the object of the present application is to improve the overall performance of dry grip performance, wet grip performance, and fuel economy, and a configuration that satisfies the parameters of the above formulas (1) and / or (2) is used as a means to achieve this.

[0011] In this specification, E* and tanδ of a rubber composition refer to the E* and tanδ of the rubber composition after vulcanization. Furthermore, E* and tanδ are values ​​obtained by conducting a viscoelasticity test on the rubber composition after vulcanization.

[0012] In this specification, "the complex modulus (E*) and loss tangent (tanδ) change reversibly due to water" means that the E* and tanδ of the rubber composition (after vulcanization) reversibly increase or decrease in the presence of water. Note that, for example, when changing from dry to wet to dry, it is sufficient that E* and tanδ change reversibly, and the E* and tanδ do not have to be the same in the previous drying state and the subsequent drying state, or they may be the same in the previous drying state and the subsequent drying state.

[0013] In this specification, E* and tanδ in a dry state refer to the E* and tanδ of a rubber composition (after vulcanization) in a dry state, and specifically refer to the E* and tanδ of a rubber composition (after vulcanization) dried by the method described in the examples. In this specification, E* and tanδ when wet with water refer to the E* and tanδ of a rubber composition (after vulcanization) in a state wet with water, and specifically refer to the E* and tanδ of a rubber composition (after vulcanization) wet with water by the method described in the examples.

[0014] In this specification, E* and tanδ of a rubber composition (after vulcanization) are the complex modulus and loss tangent measured 30 minutes after the start of measurement under the conditions of a temperature of 30°C, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10 Hz, an extension mode, and a measurement time of 30 minutes.

[0015] The rubber composition (after vulcanization) preferably satisfies the following formula (1). E* when wet / E* when dry≦0.90 (1) (In the formula, E* is the complex modulus 30 minutes after the start of measurement, measured under the conditions of a temperature of 30°C, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10 Hz, an extension mode, and a measurement time of 30 minutes.) The ratio E* when wetted with water / E* when dry is preferably 0.87 or less, more preferably 0.84 or less, even more preferably 0.82 or less, and particularly preferably 0.80 or less. The lower limit of the ratio E* when wetted with water / E* when dry is not particularly limited, but is preferably 0.50 or more, more preferably 0.60 or more, even more preferably 0.70 or more, and particularly preferably 0.75 or more. Within the above range, the effect can be suitably obtained.

[0016] The rubber composition (after vulcanization) has an E* value in a dry state of preferably 4.0 MPa or more, more preferably 4.5 MPa or more, even more preferably 5.0 MPa or more, and particularly preferably 5.4 MPa or more. There is no particular upper limit to the E* value in a dry state, but it is preferably 20.0 MPa or less, more preferably 17.0 MPa or less, even more preferably 16.0 MPa or less, and particularly preferably 15.0 MPa or less. Within the above range, the effects can be suitably obtained.

[0017] The rubber composition (after vulcanization) preferably satisfies the following formula (2). Tan δ when wet / tan δ when dry ≧ 1.10 (2) (In the formula, tanδ is the loss tangent 30 minutes after the start of measurement, measured under the conditions of a temperature of 30°C, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10 Hz, an extension mode, and a measurement time of 30 minutes.) The ratio of wet tan δ to dry tan δ is preferably 1.15 or more, more preferably 1.18 or more, even more preferably 1.20 or more, and particularly preferably 1.21 or more. There are no particular limitations on the upper limit of wet tan δ to dry tan δ, but it is preferably 1.60 or less, more preferably 1.50 or less, even more preferably 1.40 or less, and particularly preferably 1.35 or less. Within the above range, the effects can be suitably obtained.

[0018] The rubber composition (after vulcanization) has a dry tan δ of preferably 0.18 or more, more preferably 0.20 or more, even more preferably 0.21 or more, and particularly preferably 0.22 or more. There is no particular upper limit to the dry tan δ, but it is preferably 0.60 or less, more preferably 0.40 or less, even more preferably 0.30 or less, and particularly preferably 0.25 or less. Within the above range, the effects can be suitably obtained.

[0019] The reversible changes in E* and tan δ of the rubber composition due to water, as represented by the above formulas (1) and / or (2), can be achieved, for example, by compounding a modified rubber having at least one selected from the group consisting of carboxylic acids, sulfonic acids, and salts thereof in the molecule with the metal oxide. Specifically, for example, by combining a modified rubber having at least one selected from the group consisting of carboxylic acids, sulfonic acids, and salts thereof, such as carboxylic acid-modified SBR, with a metal oxide such as magnesium oxide, the reversible changes in E* and tan δ of the rubber composition due to water, as represented by the above formulas (1) and / or (2), can be achieved. This is thought to be achieved by the fact that, when used in combination, an ionic bond is formed between the modified rubber and the metal oxide, for example, by a cation derived from the metal oxide and an anion derived from a carboxylic acid, a sulfonic acid, or a salt thereof, and the ionic bond between the modified rubber and the metal oxide is cleaved by the addition of water, and recombined by drying the water, resulting in a decrease in E* and / or an increase in tan δ when wet with water, and an increase in E* and / or a decrease in tan δ when dry.

[0020] The dry E* can be adjusted by the type and amount of chemicals (especially rubber components, fillers, softeners such as oils) compounded into the rubber composition. For example, the dry E* tends to increase by reducing the amount of softener or increasing the amount of filler.

[0021] The dry tan δ can be adjusted by the type and amount of chemicals (particularly rubber components, fillers, softeners, resins, sulfur, vulcanization accelerators, and silane coupling agents) compounded into the rubber composition. For example, the dry tan δ tends to increase when a softener (e.g., resin) that is poorly compatible with the rubber component is used, when an unmodified rubber is used, when the amount of filler is increased, when oil as a plasticizer is increased, when sulfur is reduced, when vulcanization accelerators are reduced, or when silane coupling agents are reduced.

[0022] Furthermore, the dry E* and tanδ can be adjusted by, for example, the acidic functional group content of the modified rubber or the metal oxide content (in other words, the metal content derived from the metal oxide). Specifically, increasing the acidic functional group content of the modified rubber or the metal oxide content tends to increase the dry E* and decrease the dry tanδ.

[0023] Regarding E* and tan δ when wet, for example, by forming a rubber composition crosslinked by ionic bonds in which the modified rubber and the metal oxide are partially or entirely crosslinked by ionic bonds, the E* when wet can be lowered and / or the tan δ can be increased compared to when dry, making it possible to adjust the E* and tan δ when wet. Specifically, by using the modified rubber in combination with the metal oxide, a rubber composition crosslinked by ionic bonds can be obtained, which can lower the E* when wet and / or increase the tan δ when wet compared to when dry. Furthermore, the E* and tan δ when wet can be adjusted by the type and amount of chemicals blended into the rubber composition. For example, similar trends can be obtained for the E* and tan δ when wet by using the same methods as those for adjusting the dry E* and dry tan δ described above.

[0024] Specifically, by adjusting the dry E* and tanδ to within the desired ranges and then using a modified rubber having at least one selected from the group consisting of carboxylic acid, sulfonic acid, and salts thereof in the molecule in combination with the metal oxide, it is possible to achieve reversible changes in E* and / or tanδ of the rubber composition due to water, as represented by the above formulas (1) and / or (2).

[0025] (rubber component) The rubber composition contains, as a rubber component, carboxylic acid (carboxylic acid group (-COOH)), sulfonic acid (sulfonic acid group (-SO3H)), and salts thereof (carboxylic acid ion (-COO - ) and / or sulfonate ions (-SO3 - The modified rubber includes a modified rubber having at least one selected from the group consisting of: a carboxylic acid group and a salt thereof (a salt formed from a counter cation thereof). The salt is not particularly limited, and examples thereof include monovalent metal salts such as alkali metal salts (sodium salt, potassium salt, etc.) and divalent metal salts such as alkaline earth metal salts (calcium salt, strontium salt, etc.). Among these, a carboxylic acid group is preferred from the viewpoint of obtaining a more effective effect.

[0026] The modified rubber has at least one ionic functional group 1 selected from the group consisting of carboxylic acid, sulfonic acid, and salts thereof in the molecule, and the content of the ionic functional group 1 in 100% by mass of the rubber (100% by mass of rubber having ionic functional group 1 in the molecule) is preferably 0.5% by mass or more, more preferably 0.8% by mass or more, and even more preferably 1.0% by mass or more. There is no particular upper limit, but it is preferably 40% by mass or less, more preferably 35% by mass or less. The content of the ionic functional group 1 can be measured by performing NMR measurement and calculating the content (mass %) based on the peak corresponding to the ionic functional group 1.

[0027] In the rubber composition, the content of the modified rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 20% by mass or more, even more preferably 40% by mass or more, and particularly preferably 50% by mass or more. There is no particular upper limit, but it is preferably 90% by mass or less, more preferably 85% by mass or less, even more preferably 80% by mass or less, and particularly preferably 75% by mass or less. Within the above range, the effects can be suitably obtained.

[0028] From the viewpoint of obtaining the desired effect, the rubber constituting the skeleton of the modified rubber preferably has as its constituent unit at least one monomer selected from the group consisting of styrene, butadiene, and isoprene. Specific examples of such rubber include isoprene-based rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), and styrene-isoprene-butadiene rubber (SIBR). The rubber component may be used alone or in combination of two or more. Among these, SBR, BR, and isoprene-based rubber are preferred from the viewpoint of tire physical properties.

[0029] The SBR is not particularly limited, and examples thereof include emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), etc. These may be used alone or in combination of two or more.

[0030] The styrene content of SBR is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. The styrene content is preferably 60% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. Within the above range, the effect tends to be more favorable. In this specification, the styrene content of SBR is 1 It is calculated by H-NMR measurement.

[0031] The vinyl content of the SBR is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. The vinyl content is preferably 75% by mass or less, and more preferably 70% by mass or less. Within the above range, the effect tends to be more favorable. The vinyl content (amount of 1,2-bonded butadiene units) can be measured by infrared absorption spectroscopy.

[0032] As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., etc. can be used.

[0033] When the rubber composition contains, as the modified rubber, a modified SBR having at least one ionic functional group 1 selected from the group consisting of carboxylic acid, sulfonic acid, and salts thereof in the molecule, the content of the modified SBR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 20% by mass or more, even more preferably 40% by mass or more, and particularly preferably 50% by mass or more. There is no particular upper limit, but it is preferably 90% by mass or less, more preferably 85% by mass or less, even more preferably 80% by mass or less, and particularly preferably 75% by mass or less. Within the above range, the effects can be preferably obtained.

[0034] The BR is not particularly limited, and examples thereof include high-cis BR with a high cis content, BR containing syndiotactic polybutadiene crystals, and BR synthesized using a rare earth catalyst (rare earth BR). These may be used alone or in combination of two or more. Among these, high-cis BR with a cis content of 90% by mass or more is preferred because it improves wear resistance.

[0035] When the rubber composition contains, as the modified rubber, a modified BR having at least one ionic functional group 1 selected from the group consisting of carboxylic acid, sulfonic acid, and salts thereof in the molecule, the content of the modified BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and particularly preferably 20% by mass or more. There is no particular upper limit, but it is preferably 90% by mass or less, more preferably 85% by mass or less, even more preferably 80% by mass or less, and particularly preferably 75% by mass or less. Within the above range, the effects can be preferably obtained.

[0036] Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. NRs such as SIR20, RSS#3, and TSR20 are commonly used in the rubber industry. IRs are not particularly limited, and examples of IRs such as IR2200 are commonly used in the rubber industry. Modified NRs include deproteinized natural rubber (DPNR) and highly purified natural rubber (UPNR). Modified NRs include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Modified IRs include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used alone or in combination of two or more.

[0037] When the rubber composition contains a modified isoprene-based rubber having at least one ionic functional group 1 selected from the group consisting of carboxylic acid, sulfonic acid, and salts thereof in the molecule as the modified rubber, the content of the modified isoprene-based rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and particularly preferably 20% by mass or more. There is no particular upper limit, but it is preferably 80% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, and particularly preferably 35% by mass or less. Within the above range, the effects can be preferably obtained.

[0038] The rubber composition may contain a rubber component other than the modified rubber. The other rubber component preferably contains, for example, at least one selected from the group consisting of SBR, BR, and isoprene-based rubber. The SBR, BR, and isoprene-based rubber may be a modified rubber other than the modified rubber or an unmodified rubber. However, unmodified SBR, unmodified BR, and unmodified isoprene-based rubber are preferred, and unmodified BR and unmodified isoprene-based rubber are more preferred.

[0039] When the rubber composition contains a rubber component other than the modified rubber, the content of the other rubber component in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and particularly preferably 20% by mass or more. There is no particular upper limit, but it is preferably 80% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, and particularly preferably 35% by mass or less. Within the above ranges, the effects can be preferably obtained. Note that when an unmodified isoprene-based rubber or unmodified BR is used as the other rubber component, the content of the unmodified isoprene-based rubber and the content of the unmodified BR are also preferably in the same ranges.

[0040] (metal oxides) The rubber composition contains at least one metal oxide selected from the group consisting of lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, beryllium oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, scandium oxide, titanium oxide, vanadium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide, yttrium oxide, zirconium oxide, niobium oxide, molybdenum oxide, technetium oxide, ruthenium oxide, rhodium oxide, palladium oxide, silver oxide, hafnium oxide, tantalum oxide, tungsten oxide, osmium oxide, iridium oxide, platinum oxide, gold oxide, aluminum oxide, gallium oxide, cadmium oxide, indium oxide, tin oxide, thallium oxide, lead oxide, bismuth oxide, and polonium oxide. These metal oxides may be used alone or in combination of two or more.

[0041] Among these, from the viewpoint of optimally obtaining the effect, it is preferable to contain at least one selected from the group consisting of lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, beryllium oxide, magnesium oxide, calcium oxide, strontium oxide, and barium oxide, it is more preferable to contain at least one selected from the group consisting of beryllium oxide, magnesium oxide, calcium oxide, strontium oxide, and barium oxide, and it is even more preferable to contain magnesium oxide.

[0042] The reason why the above-mentioned effects are more pronounced when these metal oxides are used is not entirely clear, but it is presumed to be due to the following mechanism. When modified rubber containing carboxylic acid or the like in its molecule is combined with a specific metal oxide, an ionic bond is formed between the carboxylic acid or the like and the metal of the metal oxide. A similar ionic bond is also formed with transition metal oxides, resulting in water responsiveness. However, while transition metal oxides have a regular, stable, four-coordinate tetrahedral coordination structure, these specific metal oxides do not have such a structure, which is thought to result in high reinforcing properties and water responsiveness. Furthermore, since these specific metal oxides are easily dissociated by water, it is thought that their water responsiveness is further improved. Therefore, it is expected that rubber compositions using these specific metal oxides will further improve overall performance in terms of dry grip performance, wet grip performance, and fuel economy.

[0043] In the rubber composition, the content of the metal oxides (total amount of the metal oxides) is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, even more preferably 2.0 parts by mass or more, particularly preferably 2.2 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 10.0 parts by mass or less, more preferably 5.0 parts by mass or less, even more preferably 4.0 parts by mass or less, particularly preferably 3.0 parts by mass or less. Within the above ranges, the effects tend to be more favorably obtained. The total amount of at least one selected from the group consisting of lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, beryllium oxide, magnesium oxide, calcium oxide, strontium oxide, and barium oxide, the total amount of at least one selected from the group consisting of beryllium oxide, magnesium oxide, calcium oxide, strontium oxide, and barium oxide, and the content of magnesium oxide are also preferably within the same ranges.

[0044] The apparent specific gravity of the metal oxide is preferably less than 0.4 g / ml, more preferably 0.3 g / ml or less, even more preferably 0.25 g / ml or less, and is preferably 0.05 g / ml or more, more preferably 0.15 g / ml or more. Within the above ranges, the effect tends to be better. It is also preferable that the apparent specific gravity of magnesium oxide is within the same range. The apparent specific gravity of the metal oxide is a value obtained by measuring 30 ml of the apparent volume into a 50 ml measuring cylinder and calculating from the mass.

[0045] The d50 of the metal oxide is preferably less than 10 μm, more preferably 4.5 μm or less, even more preferably 1.5 μm or less, particularly preferably less than 0.75 μm, and is preferably 0.05 μm or more, more preferably 0.45 μm or more. Within the above ranges, better effects tend to be obtained. It is also preferable that the d50 of magnesium oxide is in the same range. The d50 of the metal oxide is the particle size at 50% of the integrated value in the mass-based particle size distribution curve obtained by the laser diffraction scattering method.

[0046] The nitrogen adsorption specific surface area (N2SA) of the metal oxide is preferably 100 m 2 / g or more, more preferably 115m 2 / g or more, and preferably 250m 2 / g or less, more preferably 225m 2 / g or less, more preferably 200m 2 / g or less. Within the above range, the effect tends to be better. Furthermore, it is preferable that the N2SA of magnesium oxide is also within the same range. The N2SA of the metal oxide is a value measured by the BET method in accordance with JIS Z8830:2013.

[0047] Commercially available metal oxides include those manufactured by Kyowa Chemical Industry Co., Ltd., Fujifilm Wako Pure Chemical Industries Co., Ltd., Kishida Chemical Co., Ltd., Kyowa Chemical Industry Co., Ltd., Tateho Chemical Industry Co., Ltd., JHE Co., Ltd., Nippon Chemical Industry Co., Ltd., Ako Kasei Co., Ltd., and the like.

[0048] (filler) The rubber composition preferably contains a filler. Examples of fillers that can be used include inorganic fillers such as silica, carbon black, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, and mica; and poorly dispersible fillers, all of which are well known in the rubber field. Among these, silica and carbon black are preferred.

[0049] The silica is not particularly limited, and examples thereof include dry process silica (anhydrous silica), wet process silica (hydrated silica), etc. Among these, wet process silica is preferred because it has a large number of silanol groups.

[0050] The nitrogen adsorption specific surface area (N2SA) of the silica is preferably 30 m 2 / g or more, more preferably 100m 2 / g or more, more preferably 125m 2 / g or more. The N2SA of the silica is preferably 300m 2 / g or less, more preferably 250m 2 / g or less, more preferably 200m 2 Within the above range, the effect can be suitably obtained. The N2SA of silica is a value measured by the BET method in accordance with ASTM D3037-93.

[0051] As silica, for example, products from Degussa, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., Tokuyama Corporation, etc. can be used.

[0052] In the rubber composition, the content of silica is preferably 20 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 45 parts by mass or more, and particularly preferably 50 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the content is not particularly limited, but is preferably 150 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 80 parts by mass or less. Within the above range, the effects can be suitably obtained.

[0053] When the rubber composition contains silica, it is preferable that the rubber composition further contains a silane coupling agent. The silane coupling agent is not particularly limited, and examples thereof include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)disulfide, bis(4-triethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, 3-trimethoxysilylpropyl-N Examples of such compounds include sulfide-based compounds such as N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based compounds such as 3-mercaptopropyltrimethoxysilane and 2-mercaptoethyltriethoxysilane; vinyl-based compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based compounds such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Commercially available products that can be used include, for example, products from Degussa, Momentive, Shin-Etsu Silicones Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., and Dow Corning Toray Co., Ltd. These may be used alone or in combination of two or more.

[0054] In the rubber composition, the content of the silane coupling agent is preferably 1.0 part by mass or more, more preferably 5.0 parts by mass or more, and even more preferably 8.0 parts by mass or more, per 100 parts by mass of silica. The content is also preferably 20.0 parts by mass or less, more preferably 15.0 parts by mass or less, and even more preferably 10.0 parts by mass or less. Within the above ranges, the effects can be suitably obtained.

[0055] Usable carbon blacks include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. These may be used alone or in combination of two or more. Commercially available carbon blacks include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin-Nichika Carbon Co., Ltd., and Columbia Carbon Co., Ltd.

[0056] The nitrogen adsorption specific surface area (N2SA) of carbon black is 50m 2 / g or more is preferable, and 80m 2 / g or more is more preferable, and 100m 2 / g or more is more preferable. 2 / g or less is preferable, and 150m 2 / g or less is more preferable, and 130m 2 Within the above range, the effect tends to be better. The nitrogen adsorption specific surface area of ​​carbon black can be determined according to JIS K6217-2:2001.

[0057] In the rubber composition, the carbon black content is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above range, the effect tends to be more favorably obtained.

[0058] (plasticizer) The rubber composition preferably contains a plasticizer, which is a material that imparts plasticity to the rubber component, and examples of the plasticizer include a liquid plasticizer (a plasticizer that is in a liquid state at room temperature (25°C)) and a resin (a resin that is in a solid state at room temperature (25°C)).

[0059] In the rubber composition, the content of the plasticizer (total amount of plasticizer) is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 25 parts by mass or more, and particularly preferably 30 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 90 parts by mass or less. Within the above range, the effect tends to be more favorably obtained.

[0060] Liquid plasticizers (plasticizers that are liquid at room temperature (25°C)) that can be used in the rubber composition are not particularly limited, and examples include oils, liquid polymers (liquid resins, liquid diene-based polymers, liquid farnesene-based polymers, etc.), etc. These may be used alone or in combination of two or more.

[0061] In the rubber composition, the content of the liquid plasticizer is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, even more preferably 8 parts by mass or more, and particularly preferably 10 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less. Within the above range, the effect tends to be more favorably obtained. Note that the content of the liquid plasticizer also includes the amount of oil contained in the oil-extended rubber. A similar range is also preferred for the content of the oil.

[0062] Examples of oils include process oils, vegetable oils, and mixtures thereof. Examples of process oils that can be used include paraffin-based process oils, aromatic process oils, and naphthenic process oils. Examples of vegetable oils that can be used include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice bran oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. Commercially available products include those from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Corporation, Oriso Co., Ltd., H&R Corporation, Toyokuni Oil Mills Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kosan Co., Ltd., and Nisshin Oillio Group, Ltd. Among these, process oils (paraffin-based process oils, aromatic process oils, naphthenic process oils, etc.) and vegetable oils are preferred.

[0063] Examples of liquid resins include terpene resins (including terpene phenol resins and aromatic modified terpene resins), rosin resins, styrene resins, C5 resins, C9 resins, C5 / C9 resins, dicyclopentadiene (DCPD) resins, coumarone-indene resins (including coumarone and indene simple resins), phenol resins, olefin resins, polyurethane resins, acrylic resins, etc. Hydrogenated products of these resins can also be used.

[0064] Examples of liquid diene polymers include liquid styrene butadiene copolymers (liquid SBR), liquid butadiene polymers (liquid BR), liquid isoprene polymers (liquid IR), liquid styrene isoprene copolymers (liquid SIR), liquid styrene butadiene styrene block copolymers (liquid SBS block polymers), liquid styrene isoprene styrene block copolymers (liquid SIS block polymers), liquid farnesene polymers, and liquid farnesene butadiene copolymers, all of which are liquid at 25°C. The terminals or main chains of these polymers may be modified with polar groups. Hydrogenated versions of these polymers can also be used.

[0065] Examples of the resins (resins that are solid at room temperature (25°C)) that can be used in the rubber composition include aromatic vinyl polymers, coumarone-indene resins, coumarone resins, indene resins, phenolic resins, rosin resins, petroleum resins, terpene resins, and acrylic resins that are solid at room temperature (25°C). The resins may also be hydrogenated. These may be used alone or in combination of two or more. Of these, aromatic vinyl polymers, petroleum resins, and terpene resins are preferred.

[0066] In the rubber composition, the content of the resin is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, and particularly preferably 20 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 60 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less. Within the above range, the effect tends to be more favorably obtained.

[0067] The softening point of the resin is preferably 50°C or higher, more preferably 55°C or higher, and even more preferably 60°C or higher. The upper limit is preferably 160°C or lower, more preferably 150°C or lower, and even more preferably 145°C or lower. Within the above range, the effect tends to be better obtained. The softening point of the resin is the temperature at which the ball drops when the softening point specified in JIS K6220-1:2001 is measured using a ring and ball softening point tester.

[0068] The aromatic vinyl polymer is a polymer containing an aromatic vinyl monomer as a constituent unit. For example, it may be a resin obtained by polymerizing α-methylstyrene and / or styrene, and specifically may be a homopolymer of styrene (styrene resin), a homopolymer of α-methylstyrene (α-methylstyrene resin), a copolymer of α-methylstyrene and styrene, or a copolymer of styrene and another monomer.

[0069] The coumarone-indene resin is a resin containing coumarone and indene as the main monomer components constituting the resin skeleton (main chain). Other monomer components contained in the skeleton besides coumarone and indene include styrene, α-methylstyrene, methylindene, vinyltoluene, etc.

[0070] The coumarone resin is a resin containing coumarone as a main monomer component constituting the skeleton (main chain) of the resin.

[0071] The indene resin is a resin containing indene as a main monomer component constituting the skeleton (main chain) of the resin.

[0072] The phenolic resin may be a known polymer obtained by reacting phenol with an aldehyde such as formaldehyde, acetaldehyde, or furfural in the presence of an acid or alkali catalyst. Of these, those obtained by reacting with an acid catalyst (such as novolac phenolic resin) are preferred.

[0073] Examples of the rosin resin include rosin-based resins such as natural rosin, polymerized rosin, modified rosin, ester compounds thereof, and hydrogenated products thereof.

[0074] Examples of the petroleum resin include C5 resin, C9 resin, C5 / C9 resin, dicyclopentadiene (DCPD) resin, and hydrogenated versions of these resins. Of these, DCPD resin and hydrogenated DCPD resin are preferred.

[0075] The terpene resin is a polymer containing terpene as a structural unit. Examples include polyterpene resins obtained by polymerizing terpene compounds and aromatic-modified terpene resins obtained by polymerizing terpene compounds and aromatic compounds. Examples of aromatic-modified terpene resins that can be used include terpene phenol resins made from terpene compounds and phenolic compounds, terpene styrene resins made from terpene compounds and styrene compounds, and terpene phenol styrene resins made from terpene compounds, phenolic compounds, and styrene compounds. Examples of terpene compounds include α-pinene and β-pinene, examples of phenolic compounds include phenol and bisphenol A, and examples of aromatic compounds include styrene compounds (styrene, α-methylstyrene, etc.).

[0076] The acrylic resin is a polymer containing an acrylic monomer as a constituent unit. For example, a styrene-acrylic resin having a carboxyl group and obtained by copolymerizing an aromatic vinyl monomer component with an acrylic monomer component can be used. Among them, a solvent-free carboxyl-containing styrene-acrylic resin can be preferably used.

[0077] Examples of plasticizers that can be used include products from Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, Nitto Chemical Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Co., Ltd.

[0078] (Other ingredients) The rubber composition preferably contains an antioxidant from the viewpoint of crack resistance, ozone resistance, and the like.

[0079] The antioxidant is not particularly limited, but examples thereof include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylenediamine, and the like. Examples of suitable antioxidants include p-phenylenediamine antioxidants such as amines; quinoline antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among these, p-phenylenediamine antioxidants and quinoline antioxidants are preferred, with polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline being more preferred. Commercially available products include those from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., and Flexis.

[0080] In the rubber composition, the content of the antioxidant is preferably 0.2 parts by mass or more, more preferably 0.5 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 7.0 parts by mass or less, more preferably 4.0 parts by mass or less.

[0081] The rubber composition may contain stearic acid. The content of stearic acid in the rubber composition is preferably 0.5 to 10 parts by mass or more, and more preferably 0.5 to 5 parts by mass, per 100 parts by mass of the rubber component.

[0082] As the stearic acid, conventionally known products can be used, for example, products available from NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc.

[0083] The rubber composition may contain zinc oxide. The content of zinc oxide in the rubber composition is preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass, per 100 parts by mass of the rubber component.

[0084] As the zinc oxide, conventionally known products can be used, for example, products from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used.

[0085] The rubber composition may contain wax. The content of the wax in the rubber composition is preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass, per 100 parts by mass of the rubber component.

[0086] The wax is not particularly limited, and examples thereof include petroleum waxes, natural waxes, etc. Synthetic waxes obtained by refining or chemically treating multiple waxes can also be used. These waxes may be used alone or in combination of two or more types.

[0087] Examples of petroleum-based waxes include paraffin wax and microcrystalline wax. Natural waxes are not particularly limited as long as they are derived from non-petroleum resources, and include, for example, plant-based waxes such as candelilla wax, carnauba wax, Japan wax, rice wax, and jojoba wax; animal-based waxes such as beeswax, lanolin, and spermaceti; mineral-based waxes such as ozokerite, ceresin, and petrolactam; and refined products thereof. Commercially available products include those from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Seiko Chemical Co., Ltd.

[0088] The rubber composition may contain sulfur in order to form appropriate crosslinked chains in polymer chains and to provide a good balance of the above performances.

[0089] In the rubber composition, the sulfur content is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and even more preferably 0.7 part by mass or more, per 100 parts by mass of the rubber component, and is preferably 6.0 parts by mass or less, more preferably 4.0 parts by mass or less, and even more preferably 3.0 parts by mass or less.

[0090] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, etc., which are commonly used in the rubber industry. Commercially available products include those from Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanzuri Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. These may be used alone or in combination of two or more.

[0091] The rubber composition may contain a vulcanization accelerator. In the rubber composition, the content of the vulcanization accelerator is usually 0.3 to 10 parts by mass, and preferably 0.5 to 7 parts by mass, per 100 parts by mass of the rubber component.

[0092] The type of vulcanization accelerator is not particularly limited, and commonly used ones can be used. Examples of the vulcanization accelerator include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazyl sulfenamide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, Nt-butyl-2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, di-orthotolylguanidine, and orthotolylbiguanidine. These may be used alone or in combination of two or more. Among these, sulfenamide vulcanization accelerators and guanidine vulcanization accelerators are preferred.

[0093] Among the vulcanization accelerators, sulfenamide vulcanization accelerators and guanidine vulcanization accelerators are preferred. The content of the sulfenamide vulcanization accelerator is not particularly limited, but is preferably 0.3 to 4.0 parts by mass, preferably 0.5 to 2.5 parts by mass, and more preferably 0.7 to 1.6 parts by mass, per 100 parts by mass of the rubber component. The content of the guanidine vulcanization accelerator is not particularly limited, but is preferably 0.5 to 5.0 parts by mass, preferably 0.8 to 3.0 parts by mass, and more preferably 1.0 to 2.3 parts by mass, per 100 parts by mass of the rubber component.

[0094] In addition to the above components, the rubber composition may contain additives such as a mold release agent and a pigment, which are commonly used in accordance with the field of application.

[0095] The rubber composition can be produced by a known method. For example, the rubber composition can be produced by kneading the components using a rubber kneading device such as an open roll or a Banbury mixer, and optionally crosslinking the components. The kneading conditions are as follows: the kneading temperature is usually 50 to 200°C, preferably 80 to 190°C, and the kneading time is usually 30 seconds to 30 minutes, preferably 1 minute to 30 minutes.

[0096] The tire component for which the rubber composition is used is not particularly limited, but it can be suitably used for the tread (cap tread).

[0097] <Tires> The rubber composition can be suitably used for tires. Examples of tires include pneumatic tires and non-pneumatic tires, with pneumatic tires being preferred. In particular, the rubber composition can be suitably used as summer tires and winter tires (studless tires, snow tires, studded tires, etc.). Tires can be used for passenger car tires, large passenger car tires, large SUV tires, heavy-duty tires for trucks, buses, etc., light truck tires, motorcycle tires, racing tires (high-performance tires), etc.

[0098] A tire is manufactured by a conventional method using the above rubber composition. For example, a rubber composition containing various materials is extruded to fit the shape of tire components while still unvulcanized, and molded together with other tire components in a tire building machine by a conventional method to form an unvulcanized tire. The unvulcanized tire is then heated and pressurized in the vulcanizer to obtain a tire.

[0099] An example of a tire using the rubber composition will be described with reference to FIG. 1, the up-down direction is the radial direction of the tire 2, the left-right direction is the axial direction of the tire 2, and the direction perpendicular to the paper surface is the circumferential direction of the tire 2. The tread 4 includes a cap layer 30 and a base layer 28, and it is preferable that the cap layer 30 is made of the rubber composition.

[0100] Although FIG. 1 shows an example of a two-layer tread 4 consisting of a cap layer 30 and a base layer 28, a single-layer tread or a tread having a structure of three or more layers may also be used. In either case, it is desirable that the outermost layer that comes into contact with the road surface is made of the rubber composition.

[0101] In the tire 2, each sidewall 6 extends substantially radially inward from an end of the tread 4. A radially outer portion of each sidewall 6 is joined to the tread 4. A radially inner portion of each sidewall 6 is joined to a clinch 10. The sidewall 6 can prevent damage to the carcass 14.

[0102] Each wing 8 is located between the tread 4 and the sidewall 6. The wing 8 is joined to each of the tread 4 and the sidewall 6.

[0103] Each clinch 10 is located approximately radially inward of the sidewall 6. The clinches 10 are located axially outward of the beads 12 and the carcass 14.

[0104] Each bead 12 is located axially inward of the clinch 10. The bead 12 includes a core 32 and an apex 34 extending radially outward from the core 32. The core 32 is preferably ring-shaped and includes a wound non-extensible wire. The apex 34 tapers radially outward.

[0105] The carcass 14 includes a carcass ply 36. In the tire 2, the carcass 14 is made up of one carcass ply 36, but may be made up of two or more carcass plies.

[0106] In the tire 2, the carcass ply 36 is laid between the beads 12 on both sides and extends along the tread 4 and the sidewall 6. The carcass ply 36 is folded back from the inside to the outside in the axial direction around each core 32. This folding back forms a main portion 36a and a pair of folded back portions 36b in the carcass ply 36. That is, the carcass ply 36 includes the main portion 36a and the pair of folded back portions 36b.

[0107] Although not shown, the carcass ply 36 preferably comprises a large number of parallel cords and a topping rubber. The absolute value of the angle that each cord forms with respect to the equator plane is preferably 75° to 90°. In other words, the carcass 14 preferably has a radial structure.

[0108] The belt 16 is located radially inward of the tread 4. The belt 16 is laminated with the carcass 14. The belt 16 reinforces the carcass 14. The belt 16 is made up of an inner layer 38 and an outer layer 40. As is clear from FIG. 1 , it is desirable that the width of the inner layer 38 is slightly larger than the width of the outer layer 40 in the axial direction. In this tire 2, the axial width of the belt 16 is preferably 0.6 times or more and 0.9 times or less the cross-sectional width of the tire 2 (see JATMA).

[0109] Although not shown, each of the inner layer 38 and the outer layer 40 preferably comprises a large number of cords arranged in parallel and a topping rubber. In other words, the belt 16 includes a large number of cords arranged in parallel. Each cord is inclined with respect to the equatorial plane. The absolute value of the inclination angle is generally 10° or more and 35° or less. The inclination direction of the cords of the inner layer 38 with respect to the equatorial plane is opposite to the inclination direction of the cords of the outer layer 40 with respect to the equatorial plane.

[0110] The band 18 is located radially outside the belt 16. In the axial direction, the band 18 has a width equal to the width of the belt 16. The band 18 may also have a width greater than the width of the belt 16.

[0111] Although not shown, the band 18 is preferably made of a cord and a topping rubber. The cord is wound spirally. The band 18 has a so-called jointless structure. The cord extends substantially in the circumferential direction. The angle of the cord with respect to the circumferential direction is preferably 5° or less, and more preferably 2° or less. The cord restrains the belt 16, thereby suppressing lifting of the belt 16.

[0112] The belt 16 and the band 18 form a reinforcing layer. The reinforcing layer may be formed of the belt 16 alone.

[0113] The inner liner 20 is located inside the carcass 14. The inner liner 20 is bonded to the inner surface of the carcass 14. A typical base rubber of the inner liner 20 is butyl rubber or halogenated butyl rubber. The inner liner 20 maintains the internal pressure of the tire 2.

[0114] Each chafer 22 is located near a bead 12. In this embodiment, the chafer 22 is preferably made of a cloth with rubber impregnated into the cloth. The chafer 22 may be integral with the clinch 10.

[0115] In this tire 2, the tread 4 has main grooves 42 as the grooves 26. As shown in FIG. 1 , a plurality of main grooves 42, specifically three main grooves 42, are formed in the tread 4. These main grooves 42 are spaced apart in the axial direction. The three main grooves 42 formed in the tread 4 form four ribs 44 extending in the circumferential direction. In other words, the spaces between the ribs 44 constitute the main grooves 42.

[0116] Each main groove 42 extends in the circumferential direction. The main grooves 42 are continuous and uninterrupted in the circumferential direction. The main grooves 42 facilitate the drainage of water present between the road surface and the tire 2, for example, in rainy weather. This allows the tire 2 to maintain sufficient contact with the road surface even when the road surface is wet.

[0117] In the tire 2 having the tread 4 made of the rubber composition, the negative ratio (S) of the tread 4 is preferably 50% or less. The negative ratio (S) of the tread 4 is preferably 40% or less, more preferably 35% or less, and even more preferably 30% or less. The negative ratio is preferably 5% or more, more preferably 10% or more, and even more preferably 15% or more. When it is within the above range, better effects tend to be obtained.

[0118] The reason why such an effect is obtained is not entirely clear, but it is presumed to be due to the following mechanism. As mentioned above, by satisfying the above formulas (1) and (2), when the tire is wet, the friction (μ) on a wet road surface is improved due to an increase in the contact area with the road surface and / or an increase in energy loss, improving wet grip performance. When the tire is dry, ionic bonding occurs again, and the complex modulus E* returns to its original state, presumably maintaining good friction (μ) and fuel economy when traveling on dry roads. However, it is believed that a low negative ratio of the tread further improves friction (μ) on a wet road surface and further improves wet grip performance. Therefore, it is presumed that a tire having a tread made of the above rubber composition will have improved overall performance in terms of dry grip performance, wet grip performance, and fuel economy.

[0119] In a tire 2 having a tread 4 made of the rubber composition, it is preferable that the wet E* and dry E* of the rubber composition and the negative rate S (%) of the tread 4 satisfy the following formula (3). (E* when wet / E* when dry) × S≦30.0 (3) (E* when wet / E* when dry) x S is preferably 27.0% or less, more preferably 26.0% or less, and even more preferably 25.0% or less. There is no particular lower limit, but it is preferably 5.0% or more, more preferably 10.0% or more, and even more preferably 15.0% or more. Within the above range, better effects tend to be obtained.

[0120] The reason why such an effect is obtained is not entirely clear, but it is presumed to be due to the following mechanism. As mentioned above, it is presumed that by satisfying the formula (1), when the tire is wet, the contact area with the road surface increases, improving friction (μ) on wet roads and improving wet grip performance, and when the tire is dry, ionic bonding occurs again, restoring E*, thereby maintaining good friction (μ) and fuel economy when traveling on dry roads. However, it is believed that a low negative ratio of the tread further improves friction (μ) on wet roads and further improves wet grip performance. Therefore, it is presumed that a tire having a tread made of a rubber composition that satisfies the formula (3) will have improved overall performance in terms of dry grip performance, wet grip performance, and fuel economy.

[0121] In a tire 2 having a tread 4 made of the rubber composition, it is preferable that the tan δ of the rubber composition when wet and when dry, and the negative rate S (%) of the tread 4 satisfy the following formula (4). (tanδ when wet / tanδ when dry) / S≧0.030 (4) (tan δ when wet with water / tan δ when dry) / S is preferably 0.035 (1 / %) or more, more preferably 0.040 (1 / %) or more, and even more preferably 0.042 (1 / %) or more. There is no particular upper limit, but it is preferably 0.100 (1 / %) or less, more preferably 0.060 (1 / %) or less, and even more preferably 0.050 (1 / %) or less. Within the above range, better effects tend to be obtained.

[0122] The reason why such an effect is obtained is not entirely clear, but it is presumed to be due to the following mechanism. As mentioned above, it is presumed that by satisfying the formula (2), when the tire is wet, the friction (μ) on a wet road surface increases due to increased energy loss, improving wet grip performance, and when the tire is dry, ionic bonding occurs again, restoring tan δ, thereby maintaining good friction (μ) and fuel economy when traveling on dry roads. However, it is believed that a low negative ratio of the tread further improves the friction (μ) on a wet road surface, further improving wet grip performance. Therefore, it is presumed that a tire having a tread made of a rubber composition that satisfies the formula (4) will have improved overall performance in terms of dry grip performance, wet grip performance, and fuel economy.

[0123] The negative ratio (negative ratio within the contact area of ​​the tread portion) is the ratio of the total groove area within the contact area to the total area of ​​the contact area, and is measured by the following method. In this specification, if the tire is a pneumatic tire, the land ratio is calculated from the contact shape under normal load conditions with a normal rim and normal internal pressure. In the case of a non-pneumatic tire, the land ratio can be measured in the same way without requiring normal internal pressure. "Genuine rim" means a rim that is specified for each tire by the standard system that includes the standard on which the tire is based. For example, it means a standard rim in the case of JATMA, a "Design Rim" in the case of TRA, or a "Measuring Rim" in the case of ETRTO. "Normal internal pressure" refers to the air pressure specified for each tire by the above standards. In the case of JATMA, this means the maximum air pressure, in the case of TRA, it means the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", and in the case of ETRTO, it means "INFLATION PRESSURE". In the case of passenger car tires, it is 180kPa. "Normal load" refers to the load specified for each tire by the above standards, and means the load obtained by multiplying the maximum load capacity in the case of JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the case of TRA, and the "LOAD CAPACITY" in the case of ETRTO by 0.88. The contact shape is obtained by assembling the tire on a standard rim, applying the standard internal pressure, and leaving it to stand at 25°C for 24 hours. Then, ink is applied to the surface of the tire tread, and the tire is pressed against cardboard under a standard load (camber angle 0°) and transferred to the paper. The tire is rotated 72° in the circumferential direction and the pattern is transferred at five locations. In other words, the contact shape is obtained five times. For the five contact shapes, the average value of the maximum length in the tire axial direction is defined as L, and the average value of the length in the direction perpendicular to the axial direction is defined as W. The negative rate (%) is calculated as follows: [1-{average area of ​​five transferred contact shapes (ink areas) on cardboard / (L x W)}] x 100 (%). Here, the average value of the length or area is the simple average of the five values. [Example]

[0124] The present disclosure will be specifically described based on examples, but the present disclosure is not limited to these examples.

[0125] The various chemicals used in the examples and comparative examples will be collectively described below. Carboxylic acid-modified SBR: synthesized according to Production Example 1 below (carboxylic acid group content: 5% by mass, styrene content: 23% by mass, butadiene content: 72% by mass) Carboxylic acid-modified BR: synthesized according to Production Example 2 below (carboxylic acid group content: 5% by mass, butadiene content: 95% by mass) NR:TSR20 SBR: Nipol 1502 (E-SBR) manufactured by ZEON Corporation BR: BR150B manufactured by Ube Industries, Ltd. Carbon black: Diablack I (N220, N2SA114m) manufactured by Mitsubishi Chemical Corporation 2 / g, DBP 114ml / 100g) Silica 1: Ultrasil VN3 (N2SA175m) manufactured by Evonik Degussa 2 / g) Silica 2: 9000GR (N2SA235m) manufactured by Evonik Degussa 2 / g) Stearic acid: NOF Corporation's "Tsubaki" stearic acid Magnesium oxide 1: Kyowamag 150 (apparent specific gravity 0.36 g / ml, d50: 4.46 μm, N2SA: 145 m) manufactured by Kyowa Chemical Industry Co., Ltd. 2 / g) Magnesium oxide 2: Kyowamag 150MF (apparent specific gravity: 0.23 g / ml, d50: 0.72 μm, N2SA: 119 m) manufactured by Kyowa Chemical Industry Co., Ltd. 2 / g) Calcium oxide: Calcium oxide manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Oil: H&R VIVATEC 400 / 500 (TDAE oil) Silane coupling agent: Si69 (bis(3-triethoxysilylpropyl)tetrasulfide) manufactured by EVONIK-DEGUSSA Resin: SYLVARES SA85 (copolymer of α-methylstyrene and styrene, Tg 43°C, softening point 85°C) manufactured by Arizona Chemical Antiaging agent: Antigen 6C (antiaging agent, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd. Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. Vulcanization accelerator DPG: Noccela D (1,3-diphenylguanidine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator NS: Noccela NS (N-tert-butyl-2-benzothiazylsulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0126] <Production Example 1: Synthesis of Carboxylic Acid-Modified SBR> (Latex Preparation) A pressure-resistant reactor equipped with a stirrer was charged with 2000 g of distilled water, 45 g of emulsifier (1), 1.5 g of emulsifier (2), 8 g of electrolyte, 250 g of styrene, 50 g of methacrylic acid, 700 g of butadiene, and 2 g of molecular weight modifier. The reactor temperature was adjusted to 5°C, and an aqueous solution containing 1 g of radical initiator and 1.5 g of SFS, and an aqueous solution containing 0.7 g of EDTA and 0.5 g of catalyst were added to the reactor to initiate polymerization. Five hours after the start of polymerization, 2 g of polymerization terminator was added to terminate the reaction, yielding a latex. (Rubber Preparation) Unreacted monomers were removed from the obtained latex by steam distillation. Then, the latex was added to alcohol and coagulated while adjusting the pH to 3 to 5 with saturated sodium chloride aqueous solution or formic acid to obtain a crumb-like polymer. The polymer was dried in a vacuum dryer at 40°C to obtain a solid rubber (emulsion polymerized rubber).

[0127] <Production Example 2: Synthesis of Carboxylic Acid-Modified BR> (Latex Preparation) A pressure reactor equipped with a stirrer was charged with 2000 g of distilled water, 45 g of emulsifier (1), 1.5 g of emulsifier (2), 8 g of electrolyte, 50 g of methacrylic acid, 950 g of butadiene, and 2 g of molecular weight modifier. The reactor temperature was adjusted to 5°C, and an aqueous solution containing 1 g of radical initiator and 1.5 g of SFS, and an aqueous solution containing 0.7 g of EDTA and 0.5 g of catalyst were added to the reactor to initiate polymerization. Five hours after the start of polymerization, 2 g of polymerization terminator was added to terminate the reaction, yielding a latex. (Rubber Preparation) Unreacted monomers were removed from the obtained latex by steam distillation. Then, the latex was added to alcohol and coagulated while adjusting the pH to 3 to 5 with saturated sodium chloride aqueous solution or formic acid to obtain a crumb-like polymer. The polymer was dried in a vacuum dryer at 40°C to obtain a solid rubber (emulsion polymerized rubber).

[0128] The materials used in Production Examples 1 and 2 are as follows: Emulsifier (1): Rosin acid soap manufactured by Harima Chemical Co., Ltd. Emulsifier (2): Fatty acid soap manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Electrolyte: Sodium phosphate manufactured by FUJIFILM Wako Pure Chemical Corporation Styrene: Styrene manufactured by FUJIFILM Wako Pure Chemical Corporation Methacrylic acid: Methacrylic acid manufactured by FUJIFILM Wako Pure Chemical Corporation Butadiene: 1,3 - Butadiene manufactured by Takachiho Chemical Industry Co., Ltd. Molecular weight regulator: tert - Dodecyl mercaptan manufactured by FUJIFILM Wako Pure Chemical Corporation Radical initiator: Paramethane hydroperoxide manufactured by NOF Corporation SFS: Sodium formaldehyde sulfoxylate manufactured by FUJIFILM Wako Pure Chemical Corporation EDTA: Sodium ethylenediaminetetraacetate manufactured by FUJIFILM Wako Pure Chemical Corporation Catalyst: Ferric sulfate manufactured by FUJIFILM Wako Pure Chemical Corporation Polymerization terminator: N,N’ - Dimethyldithiocarbamate manufactured by FUJIFILM Wako Pure Chemical Corporation Alcohol: Methanol and ethanol manufactured by Kanto Chemical Co., Inc. Formic acid: Formic acid manufactured by Kanto Chemical Co., Inc. Sodium chloride: Sodium chloride manufactured by FUJIFILM Wako Pure Chemical Corporation

[0129] <NMR measurement> 1 The content of carboxylic acid groups in the modified rubber was calculated using 1H - NMR.

[0130] (Examples and Comparative Examples) According to the formulation shown in each table, using a 16L Banbury mixer manufactured by Kobe Steel, Ltd., chemicals other than sulfur and vulcanization accelerators were kneaded at 160 °C for 4 minutes to obtain a kneaded product. Next, sulfur and vulcanization accelerators were added to the obtained kneaded product, and it was kneaded at 80 °C for 4 minutes using an open roll to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was formed into the shape of a tread and laminated together with other tire members on a tire molding machine to form an unvulcanized tire, and then vulcanized at 170 °C for 12 minutes to manufacture a test tire (size: 195 / 65R15).

[0131] <Negative rate> The negative rate of the obtained test tires was measured by the following method (the measured negative rates are shown in Tables 1 and 2). The tread contact profile of a test tire was obtained by assembling it onto a standard rim, applying standard internal pressure, and leaving it at 25°C for 24 hours. Then, ink was applied to the tire tread surface, and the tire was pressed against cardboard under a standard load (camber angle 0°) and transferred to the paper. The tire was rotated 72° circumferentially, and the transfer was performed at five locations, obtaining five contact profiles. For the five contact profiles, the average maximum length in the tire axial direction was defined as L, and the average length in the direction perpendicular to the axial direction was defined as W. The negative rate (%) was measured using the following formula. The average values ​​for length and area were calculated by simply averaging the five values. Negative rate (%) = [1-{average area of ​​five transferred contact shapes (ink areas) on cardboard / (L × W)}] × 100

[0132] The obtained test tires were subjected to the following physical property measurements and evaluations. The results are shown in the tables. The reference comparative example in Table 1 is Comparative Example 1-1, and the reference comparative example in Table 2 is Comparative Example 2-1.

[0133] <Viscoelasticity test> A viscoelasticity measurement sample measuring 40 mm in length, 3 mm in width, and 0.5 mm in thickness was taken from inside the rubber layer of the tread of each test tire, with the long side facing the tire circumferential direction. The tan δ and E* of the tread rubber were measured using an RSA series made by TA Instruments under the following conditions: temperature 30°C, initial strain 10%, dynamic strain 1%, frequency 10 Hz, extension mode, and measurement time 30 minutes, and the measured value was obtained 30 minutes after the start of measurement. The thickness direction of the sample was the radial direction of the tire.

[0134] <E* and tanδ when dry> The viscoelasticity measurement sample (length 40 mm × width 3 mm × thickness 0.5 mm) was dried at room temperature and normal pressure until it reached a constant weight. The complex modulus E* and loss tangent tanδ of the resulting dried vulcanized rubber composition (rubber piece) were measured using the viscoelasticity test method described above, and these were defined as E* and tanδ in the dry state.

[0135] <E* and tanδ when wet> The viscoelasticity was measured in water using the RSA immersion measurement jig according to the viscoelasticity test method described above, and the E* and tan δ when wet with water were determined. The water temperature was set at 30°C.

[0136] <Wet grip performance> Each test tire was mounted on all wheels of a vehicle (domestic FF 2000cc) and the braking distance from an initial speed of 100 km / h on a wet asphalt road surface was measured. The braking distance of the reference comparative example was set to 100, and each compounding was expressed as an index. The higher the index, the better the wet grip performance.

[0137] <Dry grip performance> Each test tire was mounted on all wheels of a vehicle (domestic FF 2000cc) and the braking distance from an initial speed of 100 km / h on a dry asphalt road was measured. The braking distance of the reference comparative example was set to 100, and each compounding was expressed as an index. The higher the index, the better the dry grip performance.

[0138] <Fuel efficiency (rolling resistance)> Using a rolling resistance tester, the rolling resistance was measured when the test tire was run on a rim (15x6JJ), with an internal pressure (230kPa), a load (3.43kN), and at a speed (80km / h), and the result was expressed as an index, with the reference comparative example being set at 100. The higher the index, the better the fuel economy on dry roads.

[0139] [Table 1]

[0140] [Table 2]

[0141] From each table, it can be seen that the tires of the examples having treads made of rubber compositions containing modified rubber having at least one selected from the group consisting of carboxylic acids, sulfonic acids, and salts thereof in the molecule and the metal oxide, and satisfying formula (1) and / or (2), had significantly superior overall performance in dry grip performance, wet grip performance, and fuel economy (expressed as the sum of three indices of dry grip performance, wet grip performance, and fuel economy).

[0142] The present disclosure (1) relates to a modified rubber having at least one selected from the group consisting of carboxylic acids, sulfonic acids, and salts thereof in the molecule; at least one metal oxide selected from the group consisting of lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, beryllium oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, scandium oxide, titanium oxide, vanadium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide, yttrium oxide, zirconium oxide, niobium oxide, molybdenum oxide, technetium oxide, ruthenium oxide, rhodium oxide, palladium oxide, silver oxide, hafnium oxide, tantalum oxide, tungsten oxide, osmium oxide, iridium oxide, platinum oxide, gold oxide, aluminum oxide, gallium oxide, cadmium oxide, indium oxide, tin oxide, thallium oxide, lead oxide, bismuth oxide, and polonium oxide; The rubber composition has a complex modulus (E*) and a loss tangent (tan δ) that are reversibly changed by water and satisfy the following formula (1) and / or formula (2): E* when wet / E* when dry≦0.90 (1) Tan δ when wet / tan δ when dry ≧ 1.10 (2) (In the formula, E* and tanδ are the complex modulus and loss tangent measured 30 minutes after the start of measurement under the following conditions: temperature 30°C, initial strain 10%, dynamic strain 1%, frequency 10 Hz, extension mode, and measurement time 30 minutes.)

[0143] The present disclosure (2) is the rubber composition according to the present disclosure (1) that satisfies the following formula: E*≧4.5MPa when dry

[0144] The present disclosure (3) is a rubber composition according to the present disclosure (1) or (2) that satisfies the following formula: Dry tan δ≧0.20

[0145] The present disclosure (4) is a rubber composition according to any one of the present disclosures (1) to (3), wherein the rubber constituting the skeleton of the modified rubber has at least one monomer selected from the group consisting of styrene, butadiene, and isoprene as a constituent unit.

[0146] The present disclosure (5) includes a rubber component other than the modified rubber, The rubber component is the rubber composition according to any one of the present disclosures (1) to (3), which contains at least one rubber selected from the group consisting of styrene-butadiene rubber, butadiene rubber, and isoprene-based rubber.

[0147] The present disclosure (6) is the rubber composition according to any one of the present disclosures (1) to (5), wherein the metal oxide includes at least one selected from the group consisting of lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, beryllium oxide, magnesium oxide, calcium oxide, strontium oxide, and barium oxide.

[0148] The present disclosure (7) is the rubber composition according to any one of the present disclosures (1) to (6), wherein the metal oxide includes at least one selected from the group consisting of beryllium oxide, magnesium oxide, calcium oxide, strontium oxide, and barium oxide.

[0149] The present disclosure (8) is the rubber composition according to any one of the present disclosures (1) to (7), which contains 5 parts by mass or more of a resin per 100 parts by mass of the rubber component.

[0150] The present disclosure (9) is a tire having a tread made of the rubber composition according to any one of the present disclosures (1) to (8).

[0151] The present disclosure (10) is the tire according to the present disclosure (9), wherein the wet E* and dry E* of the rubber composition and the negative rate S (%) of the tread satisfy the following formula (3): (E* when wet / E* when dry) × S≦30.0 (3)

[0152] The present disclosure (11) is the tire according to the present disclosure (9) or (10), in which the tan δ when wet and the tan δ when dry of the rubber composition, and the negative rate S (%) of the tread satisfy the following formula (4): (tanδ when wet / tanδ when dry) / S≧0.030 (4)

[0153] The present disclosure (12) is the tire according to any one of the present disclosures (9) to (11), wherein the negative ratio of the tread is 40% or less. [Explanation of symbols]

[0154] 2. Pneumatic tires 4 Tread 6 Sidewall 8 Wing 10 Clinch 12 beads 14 Carcass 16 Belt 18 bands 20 Inner liner 22 Chafer 24 Tread surface 26 Groove 28 base layer 30 cap layers 32 cores 34 Apex 36 Carcass ply 36a Main part 36b Folded part 38 Inner layer 40 outer layer 42 Main groove 44 Ribs CL Equatorial plane of tire 2

Claims

1. A tire having a tread made of a vulcanized rubber composition, The vulcanized rubber composition comprises a modified rubber having at least one selected from the group consisting of carboxylic acid, sulfonic acid, and salts thereof in the molecule; at least one metal oxide selected from the group consisting of lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, beryllium oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, scandium oxide, titanium oxide, vanadium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide, yttrium oxide, zirconium oxide, niobium oxide, molybdenum oxide, technetium oxide, ruthenium oxide, rhodium oxide, palladium oxide, silver oxide, hafnium oxide, tantalum oxide, tungsten oxide, osmium oxide, iridium oxide, platinum oxide, gold oxide, aluminum oxide, gallium oxide, cadmium oxide, indium oxide, tin oxide, thallium oxide, lead oxide, bismuth oxide, and polonium oxide; The complex modulus (E*) and loss tangent (tan δ) of the vulcanized rubber composition are reversibly changed by water, and satisfy the following formula (1) and / or the following formula (2): E* when wet / E* when dry ≦ 0.90 (1) Tan δ when wet with water / tan δ when dry ≧1.10 (2) (In the formula, E* and tanδ are the complex modulus and loss tangent measured 30 minutes after the start of measurement under the conditions of a temperature of 30°C, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10 Hz, an extension mode, and a measurement time of 30 minutes.) A tire in which the wet E* and dry E* of the vulcanized rubber composition and the negative rate S (%) of the tread satisfy the following formula (3): (E* when wet / E* when dry) x S≦30.0 (3)

2. A tire having a component made of a vulcanized rubber composition, The vulcanized rubber composition comprises a modified rubber having at least one selected from the group consisting of carboxylic acid, sulfonic acid, and salts thereof in the molecule; at least one metal oxide selected from the group consisting of lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, beryllium oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, scandium oxide, titanium oxide, vanadium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide, yttrium oxide, zirconium oxide, niobium oxide, molybdenum oxide, technetium oxide, ruthenium oxide, rhodium oxide, palladium oxide, silver oxide, hafnium oxide, tantalum oxide, tungsten oxide, osmium oxide, iridium oxide, platinum oxide, gold oxide, aluminum oxide, gallium oxide, cadmium oxide, indium oxide, tin oxide, thallium oxide, lead oxide, bismuth oxide, and polonium oxide; a resin; The content of the resin is 5 parts by mass or more per 100 parts by mass of the rubber component, The vulcanized rubber composition has a complex modulus (E*) and a loss tangent (tan δ) that are reversibly changed by water, and the tire satisfies the following formula (1) and / or formula (2): E* when wet / E* when dry ≦ 0.90 (1) Tan δ when wet with water / tan δ when dry ≧1.10 (2) (In the formula, E* and tanδ are the complex modulus and loss tangent measured 30 minutes after the start of measurement under the conditions of a temperature of 30°C, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10 Hz, an extension mode, and a measurement time of 30 minutes.)

3. 3. The tire according to claim 1, wherein the vulcanized rubber composition satisfies the following formula: E*≧4.5 MPa when dry

4. The tire according to any one of claims 1 to 3, wherein the vulcanized rubber composition satisfies the following formula: tan δ when dry ≧0.20

5. 5. The tire according to claim 1, wherein the rubber constituting the skeleton of the modified rubber has as a constituent unit at least one monomer selected from the group consisting of styrene, butadiene, and isoprene.

6. the vulcanized rubber composition contains a rubber component other than the modified rubber, The tire according to any one of claims 1 to 4, wherein the rubber component contains at least one rubber selected from the group consisting of styrene-butadiene rubber, butadiene rubber, and isoprene-based rubber.

7. The tire according to any one of claims 1 to 6, wherein the metal oxide includes at least one selected from the group consisting of lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, beryllium oxide, magnesium oxide, calcium oxide, strontium oxide, and barium oxide.

8. 8. The tire according to claim 1, wherein the metal oxide comprises at least one selected from the group consisting of beryllium oxide, magnesium oxide, calcium oxide, strontium oxide, and barium oxide.

9. The tire according to claim 1, wherein the vulcanized rubber composition contains 5 parts by mass or more of a resin per 100 parts by mass of the rubber component.

10. 3. The tire of claim 2, wherein said component is a tread.

11. The tire according to claim 10, wherein E* in a water-wet state and E* in a dry state of the vulcanized rubber composition, and the negative rate S (%) of the tread satisfy the following formula (3): (E* when wet / E* when dry) x S≦30.0 (3)

12. The tire according to claim 1, 10 or 11, wherein the wet tan δ and dry tan δ of the vulcanized rubber composition and the negative rate S (%) of the tread satisfy the following formula (4): (tan δ when wet with water / tan δ when dry) / S≧0.030 (4)

13. The tire according to any one of claims 1 and 10 to 12, wherein the negative ratio of the tread is 40% or less.

Images