Rubber material for tire and tire

Abstract

PROBLEM TO BE SOLVED: To provide a rubber material for a tire that has an excellent balance of hardness, breaking strength, elongation at break, wet grip property, tear strength, etc. and a tire that uses the rubber material for a tire. SOLUTION: This rubber material for a tire contains 30-200 mass parts of a reinforcing filler and 1.7-4.0 mass parts of sulfur per 100 mass parts of a rubber component which is at least one selected from the group consisting of natural rubber and synthetic rubber. 20 mass% or more of the reinforcing filler is fumed silica, and the rubber material for a tire is vulcanized.

Description

Rubber material for tires and tires

[0001] The present invention relates to a rubber material for tires and a tire. Specifically, the present invention relates to a rubber material for tires containing fumed silica and having an excellent balance of various properties, and a tire using the same.

[0002] In recent years, with the increasing interest in automobile safety, there has been an increasing demand not only for low fuel consumption but also for driving stability. To meet this demand, there has been a demand for tires that satisfy low heat buildup with reduced rolling resistance, driving stability on both wet and dry roads, and high wear resistance. In response to these demands, efforts have been made to select and improve reinforcing fillers and rubber components.

[0003] Carbon black has traditionally been used as a reinforcing filler in tire rubber materials because it can impart high abrasion resistance to the tire rubber material. However, it is difficult to obtain a tire rubber material that has a high level of balance between wet grip performance, abrasion resistance, and fuel economy by using carbon black alone. To address this problem, wet silica has been compounded in place of carbon black. However, it is known that when wet silica is used as a filler, the amount of carbon black compounded is relatively reduced, inevitably resulting in a decrease in the fracture strength and abrasion resistance of the tire rubber material. In addition, wet silica has poor dispersibility in rubber, which increases the Mooney viscosity of the tire rubber material during kneading, resulting in poor processability in extrusion molding.

[0004] Patent Document 1 proposes the use of dry silica in addition to wet silica, and reports that reinforcing performance, fuel economy, and wet performance are improved by using dry silica with a small primary particle size and dispersing it in a diene rubber.

[0005] JP 2015-183062 A

[0006] However, rubber materials for tires are required to have not only improved reinforcing performance and fuel economy but also an excellent balance of various properties.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a rubber material for tires that has an excellent balance of fuel economy, hardness, breaking strength, breaking elongation, wet grip performance, tear strength, and the like, and a tire using the rubber material for tires.

[0008] The aspects of the present invention are as follows.

[0009] [1] A rubber material for a tire, comprising: 100 parts by mass of a rubber component that is at least one selected from the group consisting of natural rubber and synthetic rubber; 30 to 200 parts by mass of a reinforcing filler; and 1.7 to 4.0 parts by mass of sulfur, wherein 20% by mass or more of the reinforcing filler is fumed silica; and the tire rubber material is vulcanized.

[0010] [2] A tire comprising a tire component made of the rubber material for a tire according to [1] above.

[0011] According to the present invention, it is possible to provide a rubber material for tires that has an excellent balance of hardness, breaking strength, breaking elongation, wet grip performance, tear strength, abrasion resistance, and the like.

[0012] The present invention will be described in detail below based on specific embodiments in the following order: 1. Rubber material for tires 1.1. Rubber component 1.2. Reinforcing filler 1.3. Sulfur and other components 1.4. Properties of rubber material for tires 2. Manufacturing method of rubber material for tires

[0013] (1. Rubber Material for Tire) The rubber material for tire according to the present embodiment is a vulcanizate used to obtain a tire described below. The rubber material for tire contains a rubber component, a reinforcing filler, and sulfur, and contains fumed silica as the reinforcing filler.

[0014] (1.1. Rubber Component) The rubber component contained in the rubber material for a tire according to the present embodiment is at least one selected from the group consisting of natural rubber and synthetic rubber. That is, the rubber component contained in the rubber material for a tire may be only natural rubber, only synthetic rubber, or both natural rubber and synthetic rubber.

[0015] When the rubber components contained in a rubber material for tires are both natural rubber and synthetic rubber, the types and contents of the natural rubber and synthetic rubber may be determined depending on the application of the rubber material, etc.

[0016] Examples of natural rubber include natural rubber (NR) and modified natural rubbers such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), and high-purity natural rubber (HPNR). These natural rubbers may be used alone or in combination of two or more. In this embodiment, NR is preferred as the natural rubber.

[0017] There are no particular limitations on the NR, and those commonly used in the rubber industry, such as SIR20, RSS3, and TSR20, can be used.

[0018] For example, when a rubber material for a tire contains natural rubber and synthetic rubber, the content of NR in the rubber component (100 parts by mass) contained in the rubber material for a tire is preferably 30 parts by mass or more, more preferably 40 parts by mass or more, in order to improve abrasion resistance, and the content of NR is preferably 80 parts by mass or less, more preferably 75 parts by mass or less, in order to achieve the balance of the above-mentioned properties.

[0019] Examples of synthetic rubbers that can be used include isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). These synthetic rubbers may be used alone or in combination of two or more. In this embodiment, SBR and BR are preferred synthetic rubbers.

[0020] The SBR is not particularly limited, and examples thereof include unmodified solution-polymerized SBR (S-SBR), unmodified emulsion-polymerized SBR (E-SBR), and modified SBRs thereof (modified S-SBR, modified E-SBR).

[0021] For example, when a rubber material for a tire contains natural rubber and synthetic rubber, the content of SBR in the rubber component (100 parts by mass) contained in the rubber material for a tire is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, because this provides excellent processability during extrusion. Also, the content of SBR is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, because this can suppress heat generation in the rubber material.

[0022] The BR is not particularly limited, and for example, BR containing syndiotactic polybutadiene crystals can be used. Examples of BR products containing syndiotactic polybutadiene crystals include high-cis BRs such as BR1220 manufactured by Zeon Corporation and BR130B and BR150B manufactured by Ube Industries, Ltd., VCR412 and VCR617 manufactured by Ube Industries, Ltd., and BR01 manufactured by ENEOS Materials Corporation.

[0023] For example, when a rubber material for a tire contains natural rubber and synthetic rubber, the content of BR in the rubber component (100 parts by mass) contained in the rubber material for a tire is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, because this improves abrasion resistance. Also, the content of BR is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, because this can suppress heat generation in the rubber material.

[0024] For example, when the rubber material for a tire contains only synthetic rubber, examples of the synthetic rubber contained in the rubber composition for a tire according to this embodiment include isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). These synthetic rubbers may be used alone or in combination of two or more. In this embodiment, SBR and BR are preferred as the synthetic rubber.

[0025] The SBR is not particularly limited, and examples thereof include unmodified solution-polymerized SBR (S-SBR), unmodified emulsion-polymerized SBR (E-SBR), and modified SBRs thereof (modified S-SBR, modified E-SBR).

[0026] For example, the content of SBR in the synthetic rubber (100 parts by mass) contained in the rubber composition for tires is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, because this provides excellent processability during extrusion. Also, the content of SBR is preferably 90 parts by mass or less, more preferably 80 parts by mass or less, because this can suppress heat generation in the rubber material for tires.

[0027] The BR is not particularly limited, and for example, BR containing syndiotactic polybutadiene crystals can be used. Examples of BR products containing syndiotactic polybutadiene crystals include high-cis BR such as BR1220 manufactured by Zeon Corporation and BR130B and BR150B manufactured by Ube Industries, Ltd., and VCR412 and VCR617 manufactured by Ube Industries, Ltd.

[0028] For example, the content of BR in the synthetic rubber (100 parts by mass) contained in the rubber composition for tires is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, because this improves abrasion resistance, and the content of BR is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, because this can suppress heat generation in the rubber material for tires.

[0029] (1.2. Reinforcing Filler) The rubber material for tires according to this embodiment contains fumed silica, also known as dry silica, as a reinforcing filler. The reinforcing filler is contained in an amount of 30 to 200 parts by mass, preferably 40 to 120 parts by mass, and more preferably 50 to 110 parts by mass, per 100 parts by mass of the rubber component. If the content of the reinforcing filler is too low, the abrasion resistance of the resulting rubber material for tires tends to be insufficient. If the content of the reinforcing filler is too high, the reinforcing filler is not sufficiently dispersed in the rubber component, and a good vulcanizate tends not to be obtained.

[0030] The tire rubber material according to this embodiment is characterized in that the reinforcing filler contains fumed silica in an amount of 20% by mass or more. The proportion of fumed silica in the reinforcing filler is preferably 21% by mass or more, and more preferably 23% by mass or more, and the entire amount of the reinforcing filler may be fumed silica.

[0031] Fumed silica is a fine particle of silicon dioxide produced by high-temperature hydrolysis of silicon tetrachloride in an oxyhydrogen flame. Therefore, the manufacturing method of fumed silica is different from that of wet silica, and the primary particle size of the primary aggregates (smallest constituents) is smaller than that of wet silica, and the nitrogen adsorption BET specific surface area is larger. The particles of fumed silica are aggregated and fused in a beaded shape, forming bulky aggregates. In other words, fumed silica is distinguished from wet silica.

[0032] Fumed silica is divided into hydrophilic and hydrophobic fumed silica based on its properties toward water. Fumed silica has silanol groups on its surface. These silanol groups are chemically active and particularly reactive with water. Therefore, surface treatment (hydrophobic treatment) is sometimes performed to reduce the reactivity with water by reacting the silanol groups with other substances. Hydrophobically treated fumed silica is called hydrophobic fumed silica, while untreated fumed silica is called hydrophilic fumed silica.

[0033] In this embodiment, hydrophobic fumed silica and hydrophilic fumed silica are distinguished by the degree of modified hydrophobicity (M value) shown below. The degree of modified hydrophobicity (M value) is a value obtained by a measurement method utilizing the fact that hydrophobic fumed silica floats in water but is completely suspended in methanol. The method described in the examples of WO 2004 / 099075 can be used to measure the M value. When hydrophobic fumed silica and hydrophilic fumed silica are represented by the M value, hydrophobic fumed silica has an M value of 1 or more, and hydrophilic fumed silica has an M value of less than 1.

[0034] The fumed silica contained in the rubber material for tires according to the present embodiment may be either hydrophilic fumed silica or hydrophobic fumed silica, or a combination of these may be used. Hydrophilic fumed silica is thought to form a structure attributable to fumed silica more easily than hydrophobic fumed silica. The presence of such a structure in the rubber material for tires obtained by vulcanization is thought to improve the abrasion resistance of the rubber material for tires.

[0035] In this embodiment, the tap density of the fumed silica may be, for example, 45 g / L or more and 400 g / L or less. From the viewpoint of production costs, it is preferable that the tap density of the fumed silica is relatively low, and from the viewpoint of productivity, it is preferable that the tap density of the fumed silica is relatively high.

[0036] When the tap density of fumed silica is low, the fumed silica is bulky, and therefore in order to disperse it uniformly in the rubber material for tires, it is necessary to add the compounded amount in divided amounts multiple times, which tends to result in poor productivity. For this reason, the fumed silica may be used after being subjected to a compression treatment to increase the tap density of the fumed silica.

[0037] In this embodiment, the BET specific surface area of ​​the fumed silica is 180 m 2 / g or more, 200m 2 / g or more, 250m 2 / g or more, 300m 2 / g or more, 350m 2 / g or more. In particular, when the BET specific surface area of ​​the hydrophilic fumed silica is within the above range, the number of silanol groups that serve as reaction sites with the rubber component or the silane coupling agent can be sufficiently secured in the hydrophilic fumed silica. As a result, the hydrophilic fumed silica and the rubber component can be well kneaded.

[0038] The upper limit of the BET specific surface area of ​​the fumed silica is not particularly limited, but is, for example, 500 m 2If the BET specific surface area of ​​the fumed silica is too small, the flame temperature during production of the fumed silica must be increased, which tends to result in the loss of the structure unique to the fumed silica and the inability to stably produce the fumed silica.

[0039] The content of fumed silica in the rubber material for tires is as described above. When hydrophilic fumed silica and hydrophobic fumed silica are used in combination, the weight ratio of the hydrophilic fumed silica to the hydrophobic fumed silica (hydrophilic fumed silica / hydrophobic fumed silica) is preferably 100 / 0 to 0 / 100, and more preferably 95 / 5 to 60 / 40.

[0040] If the content of fumed silica is too low, the abrasion resistance of the resulting rubber material for tires tends to be insufficient, whereas if the content of fumed silica is too high, the fumed silica is not sufficiently dispersed in the synthetic rubber, and a good kneaded product tends not to be obtained.

[0041] Furthermore, the rubber material for tires may contain a reinforcing filler other than fumed silica. Examples of reinforcing fillers include carbon black, wet silica, clay, mica, talc, calcium carbonate, aluminum hydroxide, aluminum oxide, and titanium oxide. From the viewpoint of the properties of the rubber material for tires, it is preferable that the content of reinforcing fillers other than fumed silica is small. On the other hand, since fumed silica is more expensive than other reinforcing fillers, from the viewpoint of cost, the rubber material for tires may contain other reinforcing fillers.

[0042] In this embodiment, the rubber material for a tire may contain at least one selected from carbon black and wet silica as a reinforcing filler other than fumed silica.

[0043] The contents of carbon black and wet silica may be set in consideration of costs.

[0044] (1.3. Sulfur and Other Components) The rubber material for tires according to this embodiment is a material obtained by vulcanizing a rubber composition for tires containing the above-described rubber component and fumed silica. Sulfur is used for the vulcanization. The tire rubber material contains 1.7 to 4.0 parts by mass of sulfur per 100 parts by mass of the rubber component. The blended amount of sulfur is preferably 1.8 to 3.5 parts by mass, more preferably 1.9 to 3.0 parts by mass, per 100 parts by mass of the rubber component. If the blended amount of sulfur is too small, a sufficient crosslinked structure is not formed, and the hardness and strength of the vulcanizate decrease. If the blended amount of sulfur is too large, an excessive crosslinked structure is formed, and the elongation of the vulcanizate decreases.

[0045] In this embodiment, a rubber component, fumed silica, and sulfur are used, and the compounding amounts of these are controlled within appropriate ranges to obtain a rubber material for tires that has high hardness and breaking strength, and also has excellent elongation at break, and has a good balance of properties.

[0046] In particular, by controlling the ratio of the amount of sulfur to the surface area of ​​silica within a specific range, a rubber material for tires having particularly good balance of properties can be obtained. The surface area of ​​silica is determined by the average specific surface area (m 2 The amount of sulfur is the weight of sulfur used as a vulcanizing agent.

[0047] The term "surface area of ​​silica / sulfur content" refers to the surface area of ​​silica per unit amount of sulfur as a vulcanizing agent. In a preferred embodiment, the ratio of surface area of ​​silica / sulfur content is 4,500 to 10,000, and more preferably 5,000 to 9,500. If the ratio of surface area of ​​silica / sulfur content is too large (if the sulfur content is too low), the tire rubber material tends not to exhibit a good balance of properties in terms of hardness, tear strength, and fuel economy. Furthermore, if the ratio of specific surface area of ​​silica / sulfur content is too small (if the sulfur content is too high), wear resistance may be significantly impaired.

[0048] In this embodiment, the tire rubber material may contain, in addition to the above-described components (rubber, fumed silica, and sulfur), general-purpose components that are blended into tire rubber materials, such as a silane coupling agent and a lubricant.

[0049] The inclusion of a silane coupling agent in the rubber material for tires facilitates the formation of a crosslinked structure between the rubber component and the fumed silica via the silane coupling agent, thereby improving the dispersibility of the fumed silica in the rubber material for tires and improving the abrasion resistance of the rubber material for tires.

[0050] The silane coupling agent is preferably a sulfur-containing silane coupling agent, such as bis-(3-triethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)disulfide, 3-trimethoxysilylpropylbenzothiazole tetrasulfide, γ-mercaptopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, and mercapto-thiocarboxylate oligomer.

[0051] In this embodiment, from the viewpoint of the fatigue crack resistance of the tire rubber material, the silane coupling agent is preferably a sulfide-based silane coupling agent such as bis-(3-triethoxysilylpropyl) tetrasulfide, bis(3-triethoxysilylpropyl) disulfide, or 3-trimethoxysilylpropyl benzothiazole tetrasulfide.

[0052] When a silane coupling agent is used in a rubber material for tires, the content thereof is 1.5 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the rubber component. If the content of the silane coupling agent is too low, the dispersibility of the fumed silica in the rubber material for tires tends to be insufficient. If the content of the silane coupling agent is too high, the silane coupling agents tend to condense with each other, and the resulting rubber material for tires tends to have insufficient wear resistance.

[0053] In the rubber material for tires, the content of the silane coupling agent is more preferably 2.0 parts by mass or more, and even more preferably 2.5 parts by mass or more, per 100 parts by mass of the rubber component, while the content of the silane coupling agent is more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less, per 100 parts by mass of the rubber component.

[0054] In the rubber material for tires, by setting the contents of the rubber component, fumed silica, sulfur, and silane coupling agent within the above-mentioned ranges, it is possible to easily obtain a rubber material for tires that can achieve good fatigue crack resistance in addition to good abrasion resistance.

[0055] Examples of lubricants include stearic acid and process oil. A lubricant may be used alone, or two or more types may be used in combination. Examples of process oils include aromatic oils made from mineral oils, synthetic oils, paraffin oils, naphthenic oils, etc. These may be used alone, or two or more types may be used in combination.

[0056] The amount of the lubricant is not limited. For example, the amount of the lubricant is preferably 2 parts by mass or more and 60 parts by mass or less per 100 parts by mass of the rubber component. Furthermore, the amount of the lubricant is more preferably 4 parts by mass or more and even more preferably 30 parts by mass or less per 100 parts by mass of the rubber component.

[0057] If the amount of lubricant is too small, the viscosity will be high before vulcanization, resulting in poor kneading properties and the fumed silica may not be sufficiently dispersed in the rubber component, whereas if the amount of lubricant is too large, shearing will not be applied during kneading, resulting in the fumed silica not being sufficiently dispersed in the rubber component.

[0058] Furthermore, the rubber material for tires may contain various additives such as zinc oxide, antioxidants, plasticizers, vulcanization aids, liquid polymers, thermosetting resins, etc. The amounts of these additives to be added are not limited, and may be general amounts.

[0059] (1.4. Properties of Rubber Material for Tire) The rubber material for tire of this embodiment has the above-mentioned unique composition, and therefore has high hardness and breaking strength, and also has excellent elongation at break, resulting in a good balance of properties.

[0060] For example, in one embodiment, a rubber material for tires having an A hardness of 63 to 80 and a tear strength of 19 to 100 kN / m can be obtained.

[0061] Furthermore, when the hardness and breaking strength are high, the material is usually difficult to elongate and therefore has a small breaking elongation, but in one embodiment, a rubber material having a high breaking elongation is obtained, despite its high hardness and breaking strength. That is, in one embodiment, a rubber material for tires having an A hardness of 63 to 80, a breaking strength of 17 to 30 MPa, and a breaking elongation of 400 to 700% is obtained.

[0062] Rubber materials for high-performance tires are required to have a high level of balance between hardness, strength, and elongation. However, materials that achieve high hardness are generally brittle and do not easily exhibit strength or elongation. In the present invention, by using fumed silica as a reinforcing filler, high hardness is achieved with a smaller compounding amount compared to when wet-process silica is compounded. Furthermore, despite the high hardness, superior results are obtained in terms of strength and elongation compared to when the same amount of wet-process silica is compounded. Therefore, the tire rubber material according to this embodiment is suitable for use in the production of high-performance tires (high hardness).

[0063] (2. Method for producing rubber material for tire) The rubber material for tire according to the present embodiment is obtained by kneading the above-described rubber component, fumed silica, sulfur, and other components, and then adding sulfur to the mixture and vulcanizing it.

[0064] In this embodiment, the above-mentioned components are simultaneously or sequentially charged into a known kneading device such as a Banbury mixer or a kneader and kneaded. The kneading conditions may be set so that each component is sufficiently kneaded. Thereafter, appropriate amounts of sulfur and a vulcanization accelerator are added, and the mixture is heated to obtain a vulcanized rubber.

[0065] As described above, the rubber material for a tire according to the present embodiment has high hardness and breaking strength, and also has excellent breaking elongation, and therefore has a good balance of properties, and can therefore be suitably used for various tire components, particularly for the tread, base tread, sidewall, clinch, etc.

[0066] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and may be modified in various ways within the scope of the present invention.

[0067] 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.

[0068] (Preparation of Rubber Composition for Tire) The following components (A-1) to (D-4) were charged into a 0.6 L Plastomill, Model BR600, manufactured by Toyo Seiki Seisakusho, Ltd., so that the compounding amounts per 100 parts by mass of the total of synthetic rubbers (A-1) and (A-2) were as shown in Tables 1 to 5. After charging, the rotor rotation speed was adjusted to within a range of 20 to 100 rpm, and the kneaded mixture was kneaded for approximately 15 minutes while the rotation speed was adjusted so that the temperature of the kneaded mixture was within a range of 140 to 170°C. After completion of kneading, the mixture was cooled to room temperature and removed to obtain a kneaded mixture.

[0069] To the obtained kneaded mixture, (D-5) to (D-7) shown below were added in the amounts shown in Tables 1 to 5 relative to a total of 100 parts by mass of the synthetic rubbers (A-1) and (A-2), and the mixture was mixed using a 6-inch roll tester to obtain a rubber composition for a tire.

[0070] (Preparation of tire rubber material) Subsequently, the obtained tire rubber composition was press-vulcanized at 170°C for about 20 minutes to obtain a tire rubber material. Test specimens for the following evaluations were prepared from the obtained tire rubber material. The obtained test specimens were used to evaluate the following physical properties.

[0071] (A) Synthetic rubber (A-1) SBR (Asahi Kasei Corporation, Asaprene (registered trademark) Y031) (A-2) BR (ENEOS Materials Corporation, BR01) (B) Reinforcing filler (B-1) Carbon black (Tokai Carbon Co., Ltd., Seast 6, nitrogen adsorption BET specific surface area: 119 m2 / g, tap density: 400 g / L) (B-2) Wet silica (manufactured by Tosoh Silica Corporation, Nipsil AQ, nitrogen adsorption BET specific surface area: 200 m 2 / g, tap density: 300 g / L) (B-3) Hydrophilic fumed silica (Tokuyama Corporation, Reolosil QS-30C, nitrogen adsorption BET specific surface area: 300 m 2 / g, tap density: 100 g / L) (B-4) Compressed fumed silica [Preparation of uniaxial opposed compressed fumed silica] Fumed silica compressed using a uniaxial opposed compression press was prepared as follows. That is, the fumed silica of (B-3) was compressed using a Freund Turbo FT-230x80 compactor as a uniaxial opposed compression press. The roller clearance was set to 0.5 mm, the roller rotation speed to 10 rpm, the compression pressure applied to the roll to 0.3 T / cm, and the degree of vacuum of the screw feeder feeding the powder to the roller to -10 kPa, thereby obtaining compressed fumed silica with a powder tap density of 200 g / L. (B-5) Hydrophobic fumed silica (Tokuyama, Reolosil KS-30SC, nitrogen adsorption BET specific surface area: 230 m) 2 / g, tap density: 80g / L, M value: 55) (C) Silane coupling agent (C-1) Bis(triethoxysilylpropyl) disulfide (manufactured by Evonik, Si75) (D) Other components (D-1) Lubricant (Stearic acid: manufactured by NOF Corporation, Beads Stearic Acid YR) (D-2) Process oil (manufactured by Fuji Kosan Co., Ltd., Aromax 3 (TDAE Oil)) (D-3) Lubricant (Zinc oxide: manufactured by Seido Chemical Industry Co., Ltd., Zinc oxide 3 types) (D-4) Antioxidant (manufactured by Seiko Chemical Co., Ltd., Ozonone 6C)

[0072] The nitrogen adsorption BET specific surface area of ​​each of the fillers (B-1) to (B-3) was measured by the nitrogen adsorption BET method using a BELSOP MINI X manufactured by Microtrac.

[0073] (D) Other Components (D-5) Sulfur (Tsurumi Chemical Industry Co., Ltd., Kinkaji Oil-Filled Fine Sulfur) (D-6) Vulcanization Accelerator (N-Cyclohexyl-2-benzothiazole Sulfenamide (CBS): Sanshin Chemical Industry Co., Ltd., Suncerer CM-G) (D-7) Vulcanization Accelerator (Tetrabenzyl Thiuram Sulfide: Sanshin Chemical Industry Co., Ltd., TBzTD)

[0074] In the table below, Comparative Examples 1-1 to 1-6 and Examples 1-1 to 1-12 are examples in which one type of reinforcing filler was used alone, and Comparative Example 2-1 and Examples 2-1 to 2-9 are examples in which two or more types of reinforcing fillers were used in combination.

[0075]

[0076]

[0077]

[0078]

[0079]

[0080] (Shore A Hardness) For the test pieces of the obtained tire rubber material, the hardness (Shore A hardness) was measured using a durometer in accordance with JIS K6253 Type A. The results are shown in Tables 1 to 5.

[0081] (Breaking Strength and Breaking Elongation) The obtained test pieces were processed into the shape of No. 3 dumbbell-shaped test pieces, and tensile tests were carried out in accordance with JIS K6251 at a tensile speed of 500 mm / min. In the tensile test, the tensile breaking strength (MPa) and breaking elongation (%) were measured. The results are shown in Tables 1 to 5.

[0082] (Wet grip performance: tan δ at 0°C) Test pieces of the obtained tire rubber material were measured in accordance with JIS K6394 using a dynamic viscoelasticity tester (VR-7130 manufactured by Ueshima Seisakusho) under the following conditions. Tan δ (0°C) was calculated from the measured value at 0°C. Measurement temperature: 0°C Static strain: 10% Dynamic strain: ±2% Frequency: 10 Hz

[0083] (Fatigue Crack Resistance: Tear Strength) Test pieces of the obtained rubber material were punched out into rectangular shapes with long sides of 130 mm and short sides of 40 mm, and a 70 mm long incision was made from the midpoint of the short side in the long side direction to obtain trouser-shaped test pieces. The thickness of the test pieces was 1 mm. A tensile test was conducted on the trouser-shaped test pieces in accordance with JIS K6252-1 at a tensile speed of 100 mm / min, and the tear strength until the test piece broke was measured. The measured tear strength was analyzed based on JIS K6274 to calculate the tear strength. For examples using one type of reinforcing filler, the tear strength of Comparative Example 1-1 was set to 100 (standard example), and for examples using two or more types of reinforcing fillers, the tear strength of Comparative Example 2-1 was set to 100 (standard example). The tear strength index for the other comparative examples and examples was calculated using the following formula. The higher the index, the better the fatigue crack resistance. The results are shown in Tables 1 to 5. (Tear strength index) = 100 × (tear strength of Examples and Comparative Examples) / (tear strength of Standard Example)

[0084] (Wear Resistance Performance: FPS Abrasion Volume) For the test specimens of the obtained tire rubber material, the FPS abrasion volume was measured using an FPS abrasion tester (AB-2012 manufactured by Ueshima Seisakusho) under conditions of a temperature of 35°C, a load of 40N, a slip ratio of 10%, and a test time of 2 minutes. The volume loss was calculated from the FPS abrasion volume, and for examples using one type of reinforcing filler, the FPS abrasion volume of Comparative Example 1-1 was set to 100 (standard example), and for examples using two or more types of reinforcing fillers, the FPS abrasion volume of Comparative Example 2-1 was set to 100 (standard example). The abrasion index for the other comparative examples and examples was calculated using the following formula. The higher the index, the better the abrasion resistance. The results are shown in Tables 1 to 5. (Wear Index) = 100 × (loss volume of standard example) / (loss volume of examples and comparative examples)

[0085] From Tables 1 to 5, it was confirmed that the present invention can provide a rubber material for tires having an excellent balance of hardness, breaking strength, breaking elongation, wet grip properties, tear strength, abrasion resistance, etc.

Claims

1. A rubber material for tires, comprising 30 to 200 parts by mass of a reinforcing filler and 1.7 to 4.0 parts by mass of sulfur, relative to 100 parts by mass of a rubber component that is at least one selected from the group consisting of natural rubber and synthetic rubber, wherein 20% or more by mass of the reinforcing filler is fumed silica, and the material is vulcanized.

2. A tire comprising a tire component made of the rubber material for tires according to claim 1.

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