Rubber composition and tires

Abstract

To provide a rubber composition which achieves both fracture strength and anisotropy at a high level.SOLUTION: The rubber composition contains a rubber component, an inorganic fiber material, carbon black, and a coupling agent. The inorganic fiber material is one or more inorganic fiber materials selected from the group consisting of magnesium sulfate fibers, calcium silicate fibers, aluminum borate fibers, and glass fibers. The inorganic fiber material is contained in an amount of 1-50 pts.mass based on 100 pts.mass of the rubber component. The inorganic fiber material has an average diameter D of 1.0-2,000 nm, an average length L of 0.10-100 μm, and an aspect ratio L / D of 2-1,000. The content of the carbon black is 30 pts.mass or more based on 100 pts.mass of the rubber component.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a rubber composition containing an inorganic fiber material and a tire having an internal component composed of the rubber composition. [Background technology]

[0002] A technique is known for introducing anisotropy to the modulus of rubber by incorporating bio-derived nanomaterials such as cellulose fibers into tire components (for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 5691463 [Overview of the project] [Problems that the invention aims to solve]

[0004] Rubber gains strength by forming a network structure, and in the case of fibrous materials, it is thought that anisotropy can be easily obtained. However, if the dispersion state of the fibrous material within the rubber matrix is ​​poor, the fibrous material will aggregate, making it difficult to obtain anisotropy, and sufficient reinforcement to the rubber matrix will not be obtained, so the fracture strength is thought to decrease. Furthermore, conventional rubber compositions that incorporate fibrous materials have a high elastic modulus, and currently do not fully satisfy market requirements in terms of ride comfort and vibration.

[0005] The present invention aims to provide a rubber composition that achieves a high degree of balance between fracture strength and anisotropy. [Means for solving the problem]

[0006] As a result of diligent research, the inventors discovered that a rubber composition with a high degree of balance between fracture strength and anisotropy can be obtained by blending inorganic fiber materials and coupling agents, and thus completed the present invention.

[0007] In other words, the present invention is [1] A rubber composition containing rubber components, inorganic fiber materials, and a coupling agent. [2] The rubber composition described in [1] above, wherein the ratio of the 100% modulus M100a in the spinning direction to the 100% modulus M100b in the anti-spinning direction (M100a / M100b) is 1.10 or more. [3] The rubber composition according to [1] or [2] above, further containing carbon black (preferably 1 to 100 parts by mass, more preferably 5 to 80 parts by mass, per 100 parts by mass of the rubber component) [4] A rubber composition according to any one of [1] to [3] above, further containing a plasticizer (preferably 1 to 90 parts by mass, more preferably 3 to 70 parts by mass, per 100 parts by mass of the rubber component) [5] The rubber composition according to any one of [1] to [4] above, wherein the rubber component contains (preferably 5% by mass or more, more preferably 10 to 90% by mass) isoprene rubber. [6] The rubber composition according to any one of [1] to [5] above, wherein the coupling agent is a silane coupling agent. [7] A rubber composition according to any one of [1] to [6] above, containing 1 to 40 parts by mass of the coupling agent per 100 parts by mass of the rubber component. [8] The rubber composition according to any one of [1] to [7] above, wherein the coupling agent is a silane coupling agent having a sulfide group. [9] Furthermore, the adsorption specific surface area (CTAB) of cetyltrimethylammonium bromide is 180 m². 2 A rubber composition according to any one of the above [1] to [8], containing carbon black of 1g or less (preferably 1 to 100 parts by mass, more preferably 5 to 80 parts by mass per 100 parts by mass of rubber component),

[10] A rubber composition according to any one of [1] to [9] above, wherein the inorganic fiber material is contained in 1 to 50 parts by mass per 100 parts by mass of the rubber component, and the average diameter D of the inorganic fiber material is 1.0 to 2000 nm, the average length L is 0.10 to 100 μm, and the aspect ratio L / D is 2 to 1000. 〔11〕The rubber composition according to any one of the above [1] to

[10] , wherein the inorganic fiber material is one or more inorganic fiber materials selected from the group consisting of magnesium sulfate fiber, calcium silicate fiber, potassium titanate fiber, aluminum borate fiber, and sepiolite. 〔12〕A tire internal member composed of the rubber composition according to any one of the above [1] to

[11] . 〔13〕A tire provided with the tire internal member according to the above

[12] . 〔14〕Relates to the tire according to the above

[13] , wherein the tire is a passenger car tire.

Advantages of the Invention

[0008] According to the present invention, by blending an inorganic fiber material and a coupling agent, a rubber composition that highly balances fracture strength and anisotropy is provided. Further, a tire provided with a tire internal member composed of the rubber composition has improved ride comfort and handling stability in a well-balanced manner.

Embodiments for Carrying Out the Invention

[0009] The rubber composition of the present disclosure contains a rubber component, an inorganic fiber material, and a coupling agent, and thus exhibits excellent fracture strength and anisotropy.

[0010] Although not intended to be bound by theory, the following is considered as a mechanism by which the rubber composition of the present disclosure can exhibit excellent fracture strength and anisotropy.

[0011] By blending an inorganic fiber material into the rubber composition, anisotropy can be imparted to the modulus of the rubber. However, it is considered that the inorganic fiber material is more difficult to disperse in the rubber component than fillers such as carbon black. Therefore, it is considered that the entire rubber matrix cannot be reinforced, and sufficient fracture strength and anisotropy are difficult to obtain. Therefore, by blending a coupling agent together with the inorganic fiber material, the dispersibility of the inorganic fiber material in the rubber matrix is improved, the entire matrix is reinforced, and it becomes possible to orient in a uniform state. Therefore, it is considered that the anisotropy is also improved.

[0012] The rubber composition (vulcanized rubber) disclosed herein preferably has a ratio of 1.10 or higher, more preferably 1.15 or higher, and even more preferably 1.20 or higher, as an indicator of anisotropy, of 100% modulus M100a in the row direction to 100% modulus M100b in the anti-row direction (M100a / M100b, sometimes referred to as the "modulus ratio" in this specification), from the viewpoint of excellent anisotropy. On the other hand, there is no particular upper limit to the modulus ratio, but it is usually 2.00 or lower, and may be 1.80 or lower, 1.60 or lower, or 1.50 or lower. By setting the modulus ratio to 1.10 or higher, it is possible to achieve a flexible response in the anti-row direction of the inorganic fiber material oriented in a highly dispersed state by the coupling agent, while increasing the rigidity in the row direction and improving responsiveness. In this specification, "row direction" means the rolling direction when forming a sheet by extrusion or shearing, and "anti-row direction" means the direction perpendicular to the row direction.

[0013] Furthermore, when the rubber composition is used as a tire, the arrangement direction of the inorganic fibers may be in the circumferential, radial, or widthwise directions of the tire. However, from the viewpoint of improving ride comfort and handling stability in a balanced manner, it is preferable that the fibers are arranged along the circumferential direction of the tire. By oriented the inorganic fibers in the circumferential direction of the tire, a flexible response is achieved to input (vibration) from the vertical direction of the tire during rolling, and by increasing the rigidity in the orientation direction (circumferential direction of the tire), responsiveness to input during steering is improved. As a result, it is believed that ride comfort and handling stability are improved in a balanced manner.

[0014] A tire manufacturing procedure, including the preparation of a rubber composition, which is one embodiment of this disclosure, will be described in detail below. However, the following description is illustrative for the purpose of illustrating this disclosure and is not intended to limit the technical scope of the present invention to this scope only. In this specification, when a numerical range is indicated using "~", it includes the numerical values ​​at both ends of the range.

[0015] <Rubber components> Examples of rubber components that can be used in this disclosure include isoprene rubber, diene rubbers such as styrene-butadiene rubber (SBR), butadiene rubber (BR), styrene-isoprene-butadiene rubber (SIBR), chloroprene rubber (CR), and acrylonitrile-butadiene rubber (NBR); and non-diene rubbers such as ethylene-propylene-diene rubber (EPDM), butyl rubber (IIR), and halogenated butyl rubber (X-IIR). These may be used individually or in combination of two or more. The rubber component may be a rubber component containing at least one selected from the group consisting of isoprene rubber, SBR, and BR; it may be a rubber component containing isoprene rubber; it may be a rubber component containing isoprene rubber and BR; it may be a rubber component consisting only of isoprene rubber and BR; it may be a rubber component containing BR; it may be a rubber component containing BR and SBR; it may be a rubber component consisting only of BR and SBR; it may be a rubber component containing isoprene rubber, SBR, and BR-isoprene rubber; or it may be a rubber component consisting only of isoprene rubber, SBR, and BR.

[0016] The content of diene rubber in 100% by mass of the rubber component is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 85% by mass or more. Alternatively, the rubber component may consist solely of diene rubber.

[0017] (Isoprene rubber) As isoprene-based rubbers, for example, isoprene rubber (IR) and natural rubber, which are common in the tire industry, can be used. Natural rubber includes not only unmodified natural rubber (NR), but also modified natural rubbers such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), high-purity natural rubber, and grafted natural rubber. These isoprene-based rubbers may be used individually or in combination of two or more types.

[0018] NR is not particularly limited and can be any tire that is common in the tire industry, such as SIR20, RSS#3, and TSR20.

[0019] When an isoprene-based compound is included, its content 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 20% by mass or more, and particularly preferably 30% by mass or more, from the viewpoint of fracture strength. On the other hand, there is no particular upper limit to the content of isoprene-based compound in the rubber component, 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.

[0020] (SBR) SBR is not particularly limited and examples include solution-polymerized SBR (S-SBR), emulsion-polymerized SBR (E-SBR), and modified SBRs thereof (modified S-SBR, modified E-SBR), with S-SBR being preferred. Modified SBRs include SBRs with modified terminals and / or main chains, and modified SBRs coupled with tin, silicon compounds, etc. (condensates, branched structures, etc.). SBRs can be oil-expanded types with added spreading oil to adjust flexibility, or non-oil-expanded types without added spreading oil; both are usable. Examples of SBRs include those manufactured and sold by JSR Corporation, Asahi Kasei Chemicals Corporation, Nippon Zeon Corporation, etc. These SBRs may be used individually or in combination of two or more types.

[0021] From the viewpoint of grip performance, the styrene content of SBR is preferably 15% by mass or more, more preferably 18% by mass or more, and even more preferably 20% by mass or more. Furthermore, from the viewpoint of polymer dispersibility and low fuel consumption performance, it is preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 50% by mass or less. In this specification, the styrene content of SBR is as follows: 1 It is calculated by 1H-NMR measurement.

[0022] When SBR is included, its content 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, from the viewpoint of wear resistance performance. Furthermore, there is no particular upper limit to the content of SBR in the rubber component, 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.

[0023] (BR) BR is not particularly limited, and for example, BR with a cis-1,4 bond content (cis content) of less than 50% (low-cis BR), BR with a cis-1,4 bond content of 90% or more (high-cis BR), rare-earth butadiene rubber synthesized using a rare-earth element catalyst (rare-earth BR), BR containing syndiotactic polybutadiene crystals (SPB-containing BR), modified BR (high-cis modified BR, low-cis modified BR), etc., which are common in the tire industry, can be used. These BRs may be used individually or in combination of two or more types.

[0024] The cis-1,4 bond content of high-cis BR is preferably 95% or more, and more preferably 97% or more. Including high-cis BR can improve low-temperature properties and wear resistance. Examples of high-cis BR include those manufactured and sold by companies such as Nippon Zeon Co., Ltd., Ube Industries, Ltd., and JSR Corporation. Examples of rare-earth BR include those manufactured and sold by companies such as Lanxess Corporation.

[0025] SPB-containing BR refers to a type of BR in which 1,2-syndiotactic polybutadiene crystals are not simply dispersed in BR, but are chemically bonded to and dispersed in BR. Examples of SPB-containing BR include those manufactured and sold by Ube Industries, Ltd., among others.

[0026] Modified BRs include those obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, with the ends of the modified BR molecule being linked by a tin-carbon bond (tin-modified BR), and butadiene rubber having a condensed alkoxysilane compound at the active end of the butadiene rubber (modified BR for silica). Examples of such modified BRs include tin-modified polymers and S-modified polymers (modified for silica) manufactured by ZS Elastomer Co., Ltd.

[0027] When BR is included, its content 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, even more preferably 20% by mass or more, and particularly preferably 25% by mass or more, from the viewpoint of wear resistance performance. There is no particular upper limit to the content of BR in the rubber component, 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.

[0028] <Inorganic fiber materials> The rubber composition according to this disclosure contains an inorganic fiber material. By providing anisotropy in strength and rigidity with inorganic fiber material oriented in the circumferential direction of the tire, a flexible response to input (vibration) from the vertical direction of the tire during rolling is achieved, and by increasing rigidity in the orientation direction (circumferential direction of the tire), responsiveness to input during steering is improved.

[0029] The inorganic fiber materials usable in this disclosure are not particularly limited, but include, for example, magnesium sulfate fibers, calcium silicate fibers, potassium titanate fibers, aluminum borate fibers, sepiolite, glass fibers, etc. Preferably, one or more inorganic fiber materials selected from the group consisting of magnesium sulfate fibers, calcium silicate fibers, potassium titanate fibers, aluminum borate fibers, and sepiolite are used, and magnesium sulfate fibers are more preferred. The inorganic fiber materials may be used individually or in combination of two or more.

[0030] As magnesium sulfate fibers, basic magnesium sulfate fibers represented by MgSO4·5Mg(OH)2·3H2O are preferred. As calcium silicate fibers, calcium silicate fibers represented by 6CaO·6SiO2·H2O are preferred. As potassium titanate fibers, potassium titanate fibers represented by K2O·6TiO2 or K2O·8TiO2 are preferred. As aluminum borate fibers, aluminum borate represented by 9Al2O3·2B2O3 is preferred. As sepiolite, Mg8Si 12 O 30 Sepiolite represented by (OH)4(H2O)4·8H2O is preferred.

[0031] The inorganic fiber material may be a commercially available product or one manufactured by a known manufacturing method. Specific examples of inorganic fiber materials include those manufactured and sold by companies such as Ube Materials Co., Ltd., Otsuka Chemical Co., Ltd., Shikoku Chemicals Co., Ltd., and Omi Mining Co., Ltd.

[0032] From the viewpoint of the anisotropy of the rubber composition, the content of inorganic fiber material per 100 parts by mass of rubber component is preferably 1.0 part by mass or more, more preferably 1.5 parts by mass or more, even more preferably 2.0 parts by mass or more, and particularly preferably 2.5 parts by mass or more. Furthermore, from the viewpoint of the fracture strength of the rubber composition, it is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, even more preferably 40 parts by mass or less, and particularly preferably 30 parts by mass or less.

[0033] The average diameter (also called the average fiber diameter or average width) D of the inorganic fiber material is preferably 1.0 nm or more, more preferably 2.0 nm or more, and even more preferably 3.0 nm or more, from the viewpoint of the rigidity and processability of the rubber composition. Furthermore, from the viewpoint of the rigidity and fracture strength of the rubber composition, it is preferably 2000 nm or less, more preferably 1000 nm or less, even more preferably 500 nm or less, and particularly preferably 100 nm or less.

[0034] From the viewpoint of the anisotropy of the rubber composition, the average length (also called the average fiber length) L of the inorganic fiber material is preferably 0.10 μm or more, more preferably 0.15 μm or more, even more preferably 0.20 μm or more, and particularly preferably 0.50 μm or more. Furthermore, from the viewpoint of the rigidity and fracture strength of the rubber composition, it is preferably 100 μm or less, more preferably 80 μm or less, even more preferably 60 μm or less, and particularly preferably 40 μm or less.

[0035] In this disclosure, the average diameter D and average length L can be measured by scanning electron microscopy image analysis, transmission microscopy image analysis, X-ray scattering data analysis, pore electrical resistance method (Culter principle method), etc.

[0036] From the viewpoint of the anisotropy of the rubber composition, the aspect ratio L / D of the inorganic fiber material is preferably 2 or more, more preferably 4 or more, even more preferably 6 or more, and particularly preferably 8 or more. Furthermore, from the viewpoint of the fracture strength of the rubber composition, it is preferably 1000 or less, more preferably 500 or less, even more preferably 250 or less, and particularly preferably 100 or less.

[0037] <Coupling agent> The rubber composition relating to this disclosure contains a coupling agent. Inorganic fiber materials are less easily dispersed in rubber components compared to fillers such as carbon black, but the inclusion of a coupling agent improves the dispersibility of the inorganic fiber materials and also improves their anisotropy.

[0038] The coupling agents usable in this disclosure are not particularly limited, but include silane coupling agents that bond with silica and rubber components, and carbon coupling agents that bond with carbon black and rubber components.

[0039] (Silane coupling agent) The silane coupling agent is not particularly limited, and in the rubber industry, any silane coupling agent that has been conventionally used in combination with silica can be used. For example, a silane coupling agent having a mercapto group as described below; a silane coupling agent having a sulfide group such as bis(3-triethoxysilylpropyl)disulfide and bis(3-triethoxysilylpropyl)tetrasulfide; a silane coupling agent having a vinyl group such as vinyltriethoxysilane and vinyltrimethoxysilane; a silane coupling agent having an amino group such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and 3-(2-aminoethyl)aminopropyltriethoxysilane; a glycidoxy-based silane coupling agent such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; a nitro-based silane coupling agent such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; a chloro-based silane coupling agent such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane, etc. Among them, a silane coupling agent having a sulfide group and / or a silane coupling agent having a mercapto group is preferable, and a silane coupling agent having a sulfide group is more preferable. These silane coupling agents may be used alone or in combination of two or more.

[0040] The silane coupling agent having a mercapto group is preferably a compound represented by the following formula (1) and / or a compound containing a bonding unit A represented by the following formula (2) and a bonding unit B represented by the following formula (3).

Chemical formula

[0041] Examples of compounds represented by formula (1) include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and the compound represented by the following chemical formula (4) (Si363 manufactured by Evonik Degussa). The compound represented by the following chemical formula (4) can be preferably used. These may be used individually or in combination of two or more. [ka]

[0042] Compounds containing the bonding unit A shown in formula (2) and the bonding unit B shown in formula (3) include, for example, those manufactured and sold by Momentive, Inc. These may be used individually or in combination of two or more types.

[0043] (Carbon coupling agent) Examples of carbon coupling agents, though not particularly limited, include tetrasulfide compounds such as bis(dimethylaminoethyl)tetrasulfide (DME) and bis(dimethylaminopropyl)tetrasulfide (DMP); benzimidazole compounds such as 1,2-bis(benzimidazol-2)ethane (EBZ) and 1,4'-bis(mercaptobenzimidazol-2)butane (C4SBZ); and pyrithione metal salts. These carbon coupling agents may be used individually or in combination of two or more.

[0044] From the viewpoint of improving the dispersibility of the inorganic fiber material, the content of the coupling agent (preferably a silane coupling agent) per 100 parts by mass of the rubber component is preferably 1.0 part by mass or more, more preferably 1.5 parts by mass or more, and even more preferably 2.0 parts by mass or more. Furthermore, from the viewpoint of fracture strength, it is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less.

[0045] When the content of inorganic fiber material is A (parts by mass) per 100 parts by mass of rubber component, the content of silica is B (parts by mass), and the content of coupling agent (preferably silane coupling agent) is X (parts by mass), it is preferable that A, B, and X satisfy the following formula (5). 0.09A+0.08B≦X≦0.35A+0.08B (5)

[0046] <Filler> The aforementioned rubber composition may contain fillers commonly used in the rubber industry, such as carbon black, silica, aluminum hydroxide, calcium carbonate, alumina, clay, and talc. It is preferable to include carbon black, and more preferable to include both carbon black and silica.

[0047] Because carbon black generates a high amount of heat during mixing, it is thought to promote plasticization during mixing and facilitate the reaction of inorganic fiber materials with the coupling agent, allowing them to disperse easily within the rubber matrix. At the same time, unlike inorganic fiber materials, it can provide a reinforcing effect without anisotropy, making it possible to impart the minimum necessary fracture strength in the anti-array direction of the inorganic fibers. On the other hand, silica has a less effective reinforcing effect than carbon black and inorganic fiber materials, but it can provide flexible reinforcement, making it possible to reinforce the entire rubber matrix while ensuring flexibility in the anti-array direction.

[0048] (Carbon Black) The carbon black used is not particularly limited and can be any that is common in the tire industry, such as GPF, FEF, HAF, ISAF, SAF, etc. Specifically, N110, N115, N120, N125, N134, N135, N219, N220, N231, N234, N293, N299, N326, N330, N339, N343, N347, N351, N356, N358, N375, N539, N550, N582, N630, N642, N650, N660, N683, N754, N762, N765, N772, N774, N787, N907, N908, N990, N991, etc. can be suitably used, as can other proprietary synthetic products. These carbon blacks may be used individually or in combination of two or more types.

[0049] The nitrogen adsorption specific surface area (N2SA) of carbon black is 30m², considering its weather resistance and reinforcing properties. 2 Preferably 35m / g or more. 2 More preferably 40m 2 A value of 250m / g or higher is even more preferable. Furthermore, from the viewpoint of dispersibility, low fuel consumption, fracture characteristics, and durability, 250m is preferable. 2 Preferably less than / g, 220m 2A value of less than / g is more preferable. In this specification, the N2SA of carbon black is the value measured in accordance with Method A of JIS K 6217-2:2017 "Carbon black for rubber - Basic properties - Part 2: Method for determining specific surface area - Nitrogen adsorption method - Single point method".

[0050] The specific surface area (CTAB) of carbon black adsorbing cetyltrimethylammonium bromide is set at 180 m² from the viewpoint of ensuring the anisotropy of the rubber composition without the rubber network becoming excessively rigid. 2 Preferably less than / g, 165m 2 More preferably less than / g, 150m 2 A value of less than / g is even more preferable. On the other hand, there is no particular limit to the lower limit of the CTAB of carbon black, but from the viewpoint of reinforcing properties, 30m is preferable. 2 Preferably 40m / g or more. 2 More preferably 50m 2 A value of 1 / g or higher is even more preferable. Here, CTAB is a value that correlates with the particle size of the carbon black, and a larger CTAB indicates smaller carbon black particle size. In this specification, the CTAB of carbon black is a value measured in accordance with JIS K 6217-3:2001 "Carbon black for rubber - Basic properties - Part 3: Method for determining specific surface area - CTAB adsorption method".

[0051] When carbon black is included, the content per 100 parts by mass of rubber component is preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, and particularly preferably 15 parts by mass or more, from the viewpoint of weather resistance and reinforcing properties. Furthermore, from the viewpoint of low fuel consumption performance, it is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, and even more preferably 60 parts by mass or less.

[0052] (silica) The silica used is not particularly limited, and common types used in the tire industry can be used, such as silica prepared by the dry method (anhydrous silica) or silica prepared by the wet method (hydrated silica). Among these, hydrated silica prepared by the wet method is preferred because it contains a large number of silanol groups. These silicas may be used individually or in combination of two or more types.

[0053] The nitrogen adsorption specific surface area (N2SA) of silica is 140 m², from the perspective of low fuel consumption and wear resistance. 2 Preferably 150m / g or more 2 More preferably 160m / g or more, 2 More preferably 170m / g or more. 2 A value of 350m or more is particularly preferable. Furthermore, from the viewpoint of low fuel consumption and processability, 350m 2 Preferably less than / g, 300m 2 More preferably less than / g, 250m 2 A value of less than or equal to / g is even more preferable. The N2SA of silica as used herein is the value measured by the BET method in accordance with ASTM D3037-93.

[0054] When silica is included, the silica content per 100 parts by mass of rubber component 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, from the viewpoint of low fuel consumption performance. Furthermore, from the viewpoint of processability, it is preferably 110 parts by mass or less, more preferably 100 parts by mass or less, even more preferably 90 parts by mass or less, and particularly preferably 80 parts by mass or less.

[0055] From the viewpoint of reinforcing properties, the total content of silica and carbon black per 100 parts by mass of rubber component is preferably 20 parts by mass or more, more preferably 25 parts by mass or more, even more preferably 30 parts by mass or more, and particularly preferably 35 parts by mass or more. From the viewpoint of processability, it is preferably 200 parts by mass or less, more preferably 170 parts by mass or less, even more preferably 150 parts by mass or less, and particularly preferably 130 parts by mass or less.

[0056] The silica content in the total silica and carbon black content is preferably 50% or more, more preferably 70% or more, and even more preferably 80% or more.

[0057] The inorganic fiber material content in the total content of inorganic fiber material, silica, and carbon black is preferably 5% by mass or more, and more preferably 8% by mass or more. This makes it easier to obtain the anisotropic effect of the inorganic fiber material. On the other hand, the inorganic fiber material content in the total content of inorganic fiber material, silica, and carbon black is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less. This makes it possible to reinforce the rubber phase only in the grain direction and prevent the strength from becoming extremely weak in the non-grain direction.

[0058] <Other compounding agents> In addition to the components mentioned above, the rubber composition may appropriately contain compounding agents commonly used in the tire industry, such as plasticizers, waxes, antioxidants, vulcanizing agents such as stearic acid, zinc oxide, and sulfur, and vulcanization accelerators. It is preferable to include a plasticizer. The inclusion of a plasticizer tends to improve anisotropy and fracture strength by reducing the viscosity of the rubber during mixing and facilitating the dispersion of inorganic fiber materials. Examples of plasticizers include oils, resin components, and liquid rubber.

[0059] Examples of oils include aromatic oils, process oils, and mineral oils such as paraffin oil. Among these, process oils are preferable for the reason of reducing the burden on the environment.

[0060] When oil is included, the oil content per 100 parts by mass of rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more, from the viewpoint of processability. Furthermore, from the viewpoint of wear resistance, it is preferably 80 parts by mass or less, more preferably 70 parts by mass or less, even more preferably 60 parts by mass or less, and particularly preferably 50 parts by mass or less. In this specification, the oil content also includes the amount of oil contained in the oil-spread rubber.

[0061] The resin components are not particularly limited, but examples include petroleum resins, terpene resins, rosin resins, and phenolic resins commonly used in the tire industry. Examples of petroleum resins include C5 petroleum resins, aromatic petroleum resins, and C5C9 petroleum resins. These resin components may be used individually or in combination of two or more.

[0062] In this specification, "C5 petroleum resin" refers to a resin obtained by polymerizing a C5 fraction. Examples of C5 fractions include petroleum fractions with 4 to 5 carbon atoms, such as cyclopentadiene, pentene, pentadiene, and isoprene. Dicyclopentadiene resin (DCPD resin) is preferably used as the C5 petroleum resin.

[0063] In this specification, "aromatic petroleum resin" refers to a resin obtained by polymerizing a C9 fraction, which may be hydrogenated or modified. Examples of C9 fractions include petroleum fractions with 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. Specific examples of aromatic petroleum resins include, for example, Coumaron indene resin, coumaron resin, indene resin, and aromatic vinyl resins are suitably used. As aromatic vinyl resins, homopolymers of α-methylstyrene or styrene, or copolymers of α-methylstyrene and styrene are preferred, and copolymers of α-methylstyrene and styrene are more preferred, for reasons of being economical, easy to process, and having excellent heat generation properties. As aromatic vinyl resins, commercially available products from companies such as Kraton and Eastman Chemical can be used.

[0064] In this specification, "C5C9 petroleum resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be hydrogenated or modified. Examples of the C5 fraction and C9 fraction include the petroleum fractions mentioned above. As C5C9 petroleum resin, commercially available products from companies such as Tosoh Corporation and LUHUA can be used.

[0065] Examples of terpene resins include polyterpene resins consisting of at least one terpene compound selected from α-pinene, β-pinene, limonene, dipentene, etc.; aromatically modified terpene resins made from the terpene compound and an aromatic compound; terpene-phenol resins made from the terpene compound and a phenolic compound; and these terpene resins that have been hydrogenated (hydrogenated terpene resins). Examples of aromatic compounds used as raw materials for aromatically modified terpene resins include styrene, α-methylstyrene, vinyltoluene, and divinyltoluene. Examples of phenolic compounds used as raw materials for terpene-phenol resins include phenol, bisphenol A, cresol, and xylenol.

[0066] Rosin-based resins are not particularly limited, but examples include natural resin rosin and rosin-modified resins obtained by hydrogenation, disproportionation, dimerization, esterification, etc.

[0067] Phenolic resins are not particularly limited, but examples include phenol-formaldehyde resin, alkylphenol-formaldehyde resin, alkylphenol-acetylene resin, and oil-modified phenol-formaldehyde resin.

[0068] When a resin component is included, its content per 100 parts by mass of the rubber component 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. Furthermore, the content of the resin component is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 20 parts by mass or less.

[0069] Liquid rubber is not particularly limited as long as it is a polymer that is in a liquid state at room temperature (25°C), but examples include liquid butadiene rubber (liquid BR), liquid styrene butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene isoprene rubber (liquid SIR), liquid farnesene rubber, etc. These liquid rubbers may be used individually or in combination of two or more.

[0070] When liquid rubber is included, its content per 100 parts by mass of rubber component 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. Furthermore, the liquid rubber content is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 20 parts by mass or less.

[0071] The content of plasticizer per 100 parts by mass of rubber component (total amount if multiple plasticizers are used in combination) is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more. Furthermore, the plasticizer content is preferably 90 parts by mass or less, more preferably 70 parts by mass or less, even more preferably 50 parts by mass or less, and particularly preferably 30 parts by mass or less. If the plasticizer content exceeds 90 parts by mass, it leads to softening of the entire rubber matrix due to the plasticizer, and sufficient reinforcement from the inorganic fiber material cannot be obtained, so anisotropy and fracture strength tend to decrease.

[0072] When wax is included, the amount of wax per 100 parts by mass of rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, from the viewpoint of weather resistance of the rubber. Furthermore, from the viewpoint of preventing whitening of the tire due to bloom, it is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less.

[0073] Anti-aging agents are not particularly limited, but examples include amine-based, quinoline-based, quinone-based, phenol-based, and imidazole-based compounds, as well as metal carbamate salts, such as N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N-isopropyl-N'-phenyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, N,N'-bis(1-methylheptyl)-p-phenylenediamine, and N,N'-bis(1,4-dimethylbutyl) Phenylenediamine-based antioxidants such as tylpentyl)-p-phenylenediamine, N,N'-bis(1-ethyl-3-methylpentyl)-p-phenylenediamine, N-4-methyl-2-pentyl-N'-phenyl-p-phenylenediamine, N,N'-diaryl-p-phenylenediamine, hindereddiaryl-p-phenylenediamine, phenylhexyl-p-phenylenediamine, and phenyloctyl-p-phenylenediamine, as well as quinoline-based antioxidants such as 2,2,4-trimethyl-1,2-dihydroquinoline polymer and 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, are preferred. These antioxidants may be used individually or in combination of two or more.

[0074] When an anti-aging agent is included, the content per 100 parts by mass of rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, from the viewpoint of the rubber's resistance to ozone cracking. Furthermore, from the viewpoint of wear resistance and wet grip performance, it is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less.

[0075] When stearic acid is included, its content per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, from the viewpoint of processability. Furthermore, from the viewpoint of vulcanization rate, it is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less.

[0076] When zinc oxide is included, its content per 100 parts by mass of rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, from the viewpoint of processability. Furthermore, from the viewpoint of wear resistance, it is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less.

[0077] Sulfur is preferably used as a vulcanizing agent. Suitable sulfur varieties include powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur.

[0078] When sulfur is included as a vulcanizing agent, the amount of sulfur per 100 parts by mass of rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, from the viewpoint of ensuring a sufficient vulcanization reaction and obtaining good grip performance and abrasion resistance. Furthermore, from the viewpoint of preventing deterioration, it is preferably 5.0 parts by mass or less, more preferably 4.5 parts by mass or less, and even more preferably 4.0 parts by mass or less.

[0079] Other examples of vulcanizing agents besides sulfur include sulfur-containing vulcanizing agents such as Takkirol V-200 manufactured by Taoka Chemical Industries, Ltd., DURALINK HTS (1,6-hexamethylene-dithiosulfate sodium dihydrate) manufactured by Flexis, and KA9188 (1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane) manufactured by Lanxess K.K., as well as organic peroxides such as dicumyl peroxide.

[0080] While there are no particular limitations on the vulcanization accelerators, examples include sulfenamide, thiazole, thiram, thiourea, guanidine, dithiocarbamate, aldehyde-amine or aldehyde-ammonia, imidazoline, and xanthate vulcanization accelerators. Among these, sulfenamide and guanidine vulcanization accelerators are preferred because they more favorably produce the desired effects, and using these two in combination is even more preferable.

[0081] Examples of sulfenamide-based vulcanization accelerators include CBS (N-cyclohexyl-2-benzothiazolyl sulfenamide), TBBS (Nt-butyl-2-benzothiazolyl sulfenamide), N-oxyethylene-2-benzothiazolyl sulfenamide, N,N'-diisopropyl-2-benzothiazolyl sulfenamide, and N,N-dicyclohexyl-2-benzothiazolyl sulfenamide. Examples of thiazole-based vulcanization accelerators include 2-mercaptobenzothiazole and dibenzothiazolyl disulfide. Examples of thiuram-based vulcanization accelerators include tetramethylthiuram monosulfide, tetramethylthiuram disulfide, and tetrabenzylthiuram disulfide (TBzTD). Examples of guanidine-based vulcanization accelerators include 1,3-diphenylguanidine (DPG), diortotolylguanidine, and orthotolylbiguanidine. These vulcanization accelerators may be used individually or in combination of two or more.

[0082] When a vulcanization accelerator is included, its content per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more. Furthermore, the content of the vulcanization accelerator per 100 parts by mass of the rubber component is preferably 8 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 6 parts by mass or less. By keeping the content of the vulcanization accelerator within the above range, it tends to be possible to ensure fracture strength and elongation.

[0083] [Method for manufacturing rubber compositions and tires] The rubber composition of this disclosure can be manufactured by known methods, for example, by kneading the components other than the vulcanizing agent and vulcanization accelerator in a known kneader commonly used in the rubber industry, such as a Banbury mixer, kneader, or open roll, then adding the vulcanizing agent and vulcanization accelerator and kneading further, and then vulcanizing. For example, in the kneading step, kneading is performed at 80°C to 170°C for 1 to 30 minutes, and in the vulcanization step, vulcanization is performed at 130°C to 190°C for 3 to 20 minutes.

[0084] The rubber composition disclosed herein is thought to achieve a flexible response to input (vibration) from the vertical direction of the tire during rolling by orienting inorganic fibers in the circumferential direction of the tire, and to improve responsiveness to steering input by increasing rigidity in the orientation direction (circumferential direction of the tire). For this reason, it is thought that it can be suitably used in continuous components in the circumferential direction of the tire, such as the cap tread, base tread, sidewall, inner sidewall layer, inner liner, strip apex, bead apex, clinch apex, bead reinforcement layer, insulation, and insert, and that similar effects can be obtained in all of them. In particular, it is suitably used as a rubber composition for internal tire components such as the base tread, inner sidewall layer, inner liner, strip apex, bead apex, bead reinforcement layer, insulation, and insert. By using the rubber composition disclosed herein as such internal tire components, it is thought that the elasticity (responsiveness) of the tire in the rolling direction can be improved while maintaining cushioning, thereby improving handling stability and ride comfort.

[0085] In this specification, "internal components" are not limited to the aforementioned components, but refer to tire components other than those that form the outer surface when the tire is mounted on the rim and inflated with air.

[0086] The tire of this disclosure can be manufactured by conventional methods using the rubber composition described above. Specifically, an unvulcanized rubber composition, in which the above components are blended with the rubber component as needed, is extruded to match the shape of the corresponding tire member to obtain a rubber composition in which the inorganic fiber material is oriented in the grain direction. Then, the rubber composition is bonded together with other tire members on a tire molding machine so that the inorganic fiber material is oriented in the circumferential direction of the tire, and molded in conventional methods to form an unvulcanized tire. This unvulcanized tire can then be manufactured by heating and pressurizing it in a vulcanizing machine. The tire of this disclosure can be either a pneumatic or non-pneumatic tire. It is also suitable for racing tires, passenger car tires, large passenger car tires, large SUV tires, and motorcycle tires, and can be used as summer tires, winter tires, and studless tires, respectively. [Examples]

[0087] This disclosure will be described based on examples, but this disclosure is not limited to the examples.

[0088] The various chemicals used in the examples and comparative examples are summarized below. NR:TSR20 BR: Ubepol BR150B (cis content: 97%) from Ube Industries, Ltd. SBR1: Toughden 3830 manufactured by Asahi Kasei Corporation (unmodified S-SBR, styrene content: 32% by mass, oil-based product containing 37.5 parts by mass of oil per 100 parts by weight of rubber component) SBR2: Asahi Kasei Corporation's Asaprene 1205 (unmodified S-SBR, styrene content: 25% by mass) Carbon Black: Cabot Japan Co., Ltd. Show Black N220 (CTAB: 110m 2 / g, N2SA:111m 2 / g) Silica: ULTRASIL(registered trademark) VN3 (N2SA: 175m) manufactured by Evonik Degussa. 2 / g) Inorganic fiber material 1: Mosshydee (basic magnesium sulfate fiber, average fiber diameter: 500-1000 nm, average fiber length: 8-30 μm) manufactured by Ube Materials Co., Ltd. Inorganic fiber material 2: Sepiolite (average fiber diameter: 5-30 nm, average fiber length: 0.2-2.0 μm) Inorganic fiber material 3: Zonohydee (calcium silicate fiber, average fiber diameter: 100-500 nm, average fiber length: 1-5 μm) manufactured by Ube Materials Co., Ltd. Silane coupling agent: Si69 (bis(3-triethoxysilylpropyl)tetrasulfide) manufactured by Evonik Degussa. Oil: Process oil X-140 manufactured by ENEOS Corporation Anti-aging agent: Ozonon 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Seiko Chemical Co., Ltd. Stearic acid: Stearic acid "Tsubaki" manufactured by NOF Corporation Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Wax: Ozoace 0355 manufactured by Nippon Seiro Co., Ltd. Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industries Co., Ltd. Vulcanization accelerator 1: Soxinol CZ (N-cyclohexyl-2-benzothiazolyl sulfenamide) manufactured by Sumitomo Chemical Co., Ltd. Vulcanization accelerator 2: Soxinol D (1,3-diphenylguanidine) manufactured by Sumitomo Chemical Co., Ltd.

[0089] (Examples and Comparative Examples) According to the formulations shown in Tables 1 and 2, materials other than sulfur and vulcanization accelerator were mixed using a Banbury mixer manufactured by Kobe Steel, Ltd. to obtain a mixture. Next, sulfur and vulcanization accelerator were added to the mixture and kneaded using an open roll to obtain an unvulcanized rubber composition. A 0.5 mm thick sheet was prepared from the obtained unvulcanized rubber composition using an open roll. The obtained unvulcanized rubber sheets were stacked to make a 1.5 mm thick sheet and press-vulcanized at 150°C for 15 minutes to produce a test vulcanized rubber sheet. Furthermore, the unvulcanized rubber composition was extruded using an extruder equipped with a die of a predetermined shape to match the shape of the sidewall inner layer, and a sidewall inner layer in which the inorganic fiber material was oriented in the grain direction was obtained. Then, the sidewall inner layer was bonded together with other tire components on a tire molding machine so that the inorganic fiber material was oriented in the circumferential direction of the tire to form an unvulcanized tire, and the tire (size: 205 / 65R15) was manufactured by press vulcanization at 170°C for 12 minutes.

[0090] <Anisotropy Test> From the vulcanized rubber sheet described above, a die was punched out in the grain direction (the direction of roll rotation when manufacturing the unvulcanized rubber sheet before vulcanization) using a JIS No. 3 dumbbell, and the tensile stress (M100a) at 100% elongation in the grain direction was measured under conditions of a tensile speed of 500 mm / min in accordance with JIS K 6251:2017. Similarly, a die was punched out in the anti-grain direction (perpendicular to the direction of roll rotation when manufacturing the unvulcanized rubber sheet before vulcanization) using a JIS No. 3 dumbbell, and the tensile stress (M100b) at 100% elongation in the anti-grain direction was measured under conditions of a tensile speed of 500 mm / min in accordance with JIS K 6251:2017. The calculated modulus ratio (M100a / M100b) is shown in Tables 1 and 2.

[0091] <Tensile Test> Using a No. 3 dumbbell-shaped test specimen made of vulcanized rubber composition, the elongation EB (%) at break and the tensile strength TB (MPa) at break of the vulcanized rubber sheet were measured in accordance with JIS K 6251:2017. From the obtained values, the fracture strength was calculated using the following formula and expressed as an index with the reference comparative example (Comparative Example 1 in Table 1, Comparative Example 3 in Table 2; the same applies hereafter) set to 100 (Fracture Strength Index). A larger index indicates superior fracture strength. Breaking strength = EB × TB / 2

[0092] <Evaluation of handling stability and ride comfort> A prototype tire was mounted on a standard rim (size = 16 x 6.5J), and the tire was inflated to an internal pressure of 210 kPa. This tire was then mounted on a 2000cc automobile. The automobile was driven on an asphalt test course, and a test driver subjectively evaluated the ride comfort and steering stability. The evaluation was on a scale of 10 points, with a baseline comparison score of 6.0 points, and a relative evaluation was used. A higher score indicates superior handling stability and ride comfort.

[0093] [Table 1]

[0094] [Table 2]

[0095] The results in Tables 1 and 2 show that the rubber composition of this disclosure, which contains inorganic fiber material and coupling agent, can achieve a high degree of balance between fracture strength and anisotropy. Furthermore, it can be seen that the tire of this disclosure equipped with an internal component made of this rubber composition has a well-balanced improvement in ride comfort and handling stability.

Claims

1. A rubber composition containing rubber components, inorganic fiber material, carbon black, and a coupling agent, The inorganic fiber material is one or more inorganic fiber materials selected from the group consisting of calcium silicate fibers, aluminum borate fibers, and glass fibers. The inorganic fiber material is contained in 1 to 50 parts by mass per 100 parts by mass of the rubber component. The inorganic fiber material has an average diameter D of 1.0 to 2000 nm, an average length L of 0.10 to 100 μm, and an aspect ratio L / D of 2 to 1000. A rubber composition wherein the carbon black content is 30 parts by mass or more per 100 parts by mass of the rubber component.

2. A rubber composition containing rubber components, inorganic fiber material, carbon black, and a coupling agent, The inorganic fiber material is one or more inorganic fiber materials selected from the group consisting of calcium silicate fibers, aluminum borate fibers, and glass fibers. The inorganic fiber material is contained in 1 to 50 parts by mass per 100 parts by mass of the rubber component. The inorganic fiber material has an average diameter D of 1.0 to 2000 nm, an average length L of 0.10 to 100 μm, and an aspect ratio L / D of 2 to 1000. The rubber component contains 5% by mass or more of butadiene rubber, A rubber composition wherein the carbon black content is 30 parts by mass or more per 100 parts by mass of the rubber component.

3. The rubber composition according to claim 2, wherein the ratio of the 100% modulus M100a in the spindle direction to the 100% modulus M100b in the anti-spindle direction (M100a / M100b) is 1.10 or more.

4. A rubber composition containing rubber components, inorganic fiber material, carbon black, and a coupling agent, The inorganic fiber material is one or more inorganic fiber materials selected from the group consisting of calcium silicate fibers, aluminum borate fibers, and glass fibers. The inorganic fiber material is contained in 1 to 50 parts by mass per 100 parts by mass of the rubber component. The inorganic fiber material has an average diameter D of 1.0 to 2000 nm, an average length L of 0.10 to 100 μm, and an aspect ratio L / D of 2 to 1000. The carbon black content is 30 parts by mass or more per 100 parts by mass of the rubber component. A rubber composition in which the ratio of the 100% modulus M100a in the spindle direction to the 100% modulus M100b in the anti-spindle direction (M100a / M100b) is 1.10 or greater.

5. The rubber composition according to any one of claims 1 to 4, further containing a plasticizer.

6. The rubber composition according to any one of claims 1 to 5, wherein the rubber component includes isoprene-based rubber.

7. The rubber composition according to any one of claims 1 to 6, wherein the coupling agent is a silane coupling agent.

8. The rubber composition according to any one of claims 1 to 7, comprising 1 to 40 parts by mass of the coupling agent per 100 parts by mass of the rubber component.

9. The rubber composition according to any one of claims 1 to 8, wherein the coupling agent is a silane coupling agent having a sulfide group.

10. Furthermore, the adsorption specific surface area (CTAB) of cetyltrimethylammonium bromide is 180 m². 2 A rubber composition according to any one of claims 1 to 9, comprising carbon black of 1 g or less.

11. The rubber composition according to any one of claims 1 to 10, wherein the inorganic fiber material is one or more inorganic fiber materials selected from the group consisting of calcium silicate fibers and aluminum borate fibers.

12. A tire using the rubber composition described in any one of claims 1 to 11 as a tire component.

13. The tire according to claim 12, wherein the tire is a passenger car tire.

Images