Rubber composition and tire

Abstract

To provide a rubber composition and a tire having enhanced fuel economy.SOLUTION: A rubber composition comprises a rubber component, silica containing biomass-derived silica, and a silane coupling agent, wherein the silica content C is 50 pts.mass or more relative to 100 pts.mass of the rubber component, the average particle diameter A of the silica is 15 nm or less, and the silica content C, the average particle diameter A of the silica, and the average carbon number E of the silane coupling agent satisfy the following formula (1): E×A / C>2.5.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a rubber composition and a tire.

Background Art

[0002] Conventionally, various performances have been required for tires, and from the viewpoint of recent environmental considerations, improvement in low fuel consumption and the like has been desired.

Summary of the Invention

Problems to be Solved by the Invention

[0003] An object of the present invention is to solve the above problems and provide a rubber composition and a tire with improved low fuel consumption.

Means for Solving the Problems

[0004] The present invention includes a rubber component, silica containing biomass-derived silica, and a silane coupling agent, the content C of the silica with respect to 100 parts by mass of the rubber component is 50 parts by mass or more, the average particle diameter A of the silica is 15 nm or less, and relates to a rubber composition in which the content C of the silica, the average particle diameter A of the silica, and the average carbon number E of the silane coupling agent satisfy the following formula (1). (1) E × A / C > 2.5

Effects of the Invention

[0005] Since the present invention is a rubber composition including a rubber component, silica containing biomass-derived silica, and a silane coupling agent, the content C of the silica with respect to 100 parts by mass of the rubber component is 50 parts by mass or more, the average particle diameter A of the silica is 15 nm or less, and the above formula (1) is satisfied, the low fuel consumption can be improved.

Brief Description of the Drawings

[0006]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0007] The rubber composition includes a rubber component, silica containing biomass-derived silica, and a silane coupling agent. The content C of the silica with respect to 100 parts by mass of the rubber component is 50 parts by mass or more, the average particle diameter A of the silica is 15 nm or less, and the content C of the silica, the average particle diameter A of the silica, and the average carbon number E of the silane coupling agent satisfy the above formula (1).

[0008] The reason why the above rubber composition exhibits the aforementioned effects is not necessarily clear, but it is presumed as follows. Biomass-derived silica has many silanol groups and strong cohesive force between silicas, so it tends to have high heat generation. Also, when using silica with a small average particle diameter or blending a large amount of silica, the heat generation tends to increase. In the above rubber composition, by adjusting the content C of silica, the average particle diameter A of silica, and the carbon number E of the silane coupling agent so as to satisfy the formula (1) “E×A / C>2.5”, even when a large amount of small particle diameter silica containing biomass-derived silica is used, the surface of the silica is hydrophobized, so it is considered that the heat generation can be reduced. Therefore, it is presumed that the above rubber composition can improve fuel efficiency.

[0009] In this way, by adopting a configuration that satisfies the relationship of “E×A / C>2.5”, the problem (objective) of improving fuel efficiency is solved. That is, the parameter of “E×A / C>2.5” does not define the problem (objective). The problem of the present application is to improve fuel efficiency, and as a solution means, a configuration that satisfies the parameter is adopted.

[0010] The above rubber composition contains a rubber component. Here, the rubber component is a component that contributes to crosslinking. Generally, a polymer having a weight average molecular weight (Mw) of 10,000 or more, and a polymer component that is not extracted by acetone corresponds to the rubber component. The elastomer component is in a solid state at normal temperature (25°C).

[0011] The weight average molecular weight of the rubber component is preferably 50,000 or more, more preferably 150,000 or more, still more preferably 200,000 or more, particularly preferably 270,000 or more, and is preferably 2,000,000 or less, more preferably 1,500,000 or less, still more preferably 1,000,000 or less. When within the above range, the effect tends to be obtained better.

[0012] In this specification, the weight average molecular weight (Mw) can be determined by standard polystyrene conversion based on the measured value by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation). Also, in the case of a polymer having a modifying group, since the modifying group and the silica gel of the column interact and an accurate Mw cannot be obtained, Mw is measured before the modification treatment is carried out.

[0013] The rubber component that can be used in the above rubber composition may be an unmodified rubber or a modified rubber. Examples of the modified rubber include rubbers having a functional group that interacts with a filler such as silica. For example, a terminal-modified rubber (terminal-modified rubber having the above functional group at the terminal) in which at least one terminal of the rubber is modified with a compound (modifying agent) having the above functional group, a main-chain modified rubber having the above functional group in the main chain, a main-chain terminal-modified rubber having the above functional group in the main chain and at the terminal (for example, a main-chain terminal-modified rubber having the above functional group in the main chain and at least one terminal modified with the above modifying agent), and a terminal-modified rubber modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and having a hydroxyl group or an epoxy group introduced therein, etc. can be mentioned.

[0014] Examples of the functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imide group, a hydrazo group, an azo group, a diazo group, a carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group, an epoxy group, etc. These functional groups may have substituents. Among them, an amino group (preferably an amino group in which a hydrogen atom of the amino group is substituted with an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), and an alkoxysilyl group (preferably an alkoxysilyl group having 1 to 6 carbon atoms) are preferred.

[0015] Examples of the rubber component include diene rubbers. Examples of the diene rubber include isoprene rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), etc. In addition, examples of the rubber component include butyl rubber, fluororubber, etc. These may be used alone or in combination of two or more. Further, these rubber components may be subjected to modification treatment or hydrogenation treatment, and extended rubber extended with oil, resin, liquid rubber component, etc. may also be used. Among them, isoprene rubber, BR, and SBR are preferred, BR and SBR are more preferred, and it is even more preferred to use BR and SBR in combination. Desirable.

[0016] Examples of isoprene rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, denatured NR, denatured IR, etc. As NR, for example, those commonly used in the rubber industry such as SIR20, RSS#3, TSR20, etc. can be used. IR is not particularly limited, and for example, those commonly used in the rubber industry such as IR2200, etc. can be used. Examples of modified NR include deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc. Examples of denatured NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. Examples of denatured IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, etc. These may be used alone or in combination of two or more.

[0017] In the above rubber composition, the content of isoprene rubber in 100% by mass of the rubber component is preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 10% by mass or less, and may be 0% by mass. When within the above range, the effect tends to be preferably obtained.

[0018] BR is not particularly limited. For example, high-cis BR with a high cis content, BR containing syndiotactic polybutadiene crystals, BR synthesized using a rare-earth catalyst (rare-earth BR), etc. can be used. These may be used alone or in combination of two or more. Among them, BR preferably includes high-cis BR with a cis content of 90% by mass or more. The cis content is more preferably 95% by mass or more. The cis content can be measured by infrared absorption spectroscopy analysis.

[0019] When BR is of one type, the cis amount of BR means the cis amount of that BR. When there are multiple types, it means the average cis amount. The average cis amount of BR can be calculated by {Σ(content of each BR × cis amount of each BR)} / total content of all BRs. For example, in 100% by mass of the rubber component, when BR with a cis amount of 90% by mass is 20% by mass and BR with a cis amount of 40% by mass is 10% by mass, the average cis amount of BR is 73.3% by mass (=(20×90 + 10×40) / (20 + 10)).

[0020] In addition, either non-modified BR or modified BR can be used. Examples of the modified BR include modified BR into which a functional group similar to that of modified rubber has been introduced. Also, hydrogenated butadiene polymer (hydrogenated BR) can be used as BR.

[0021] In the above rubber composition, the content of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more, and is preferably 50% by mass or less, more preferably 40% by mass or less, still more preferably 30% by mass or less. When within the above range, the effect tends to be preferably obtained.

[0022] SBR is not particularly limited. For example, emulsion polymerization styrene-butadiene rubber (E-SBR), solution polymerization styrene-butadiene rubber (S-SBR), etc. can be used. These may be used alone or in combination of two or more.

[0023] The styrene content of SBR is preferably 5% by mass or more, more preferably 20% by mass or more, still more preferably 25% by mass or more. The styrene content is preferably 45% by mass or less, more preferably 40% by mass or less, still more preferably 35% by mass or less. When within the above range, the effect tends to be obtained better. In addition, in this specification, the styrene content 1 can be measured by 1H-NMR measurement.

[0024] The styrene amount of SBR means the styrene amount of the SBR when there is one type of SBR, and means the average styrene amount when there are multiple types. The average styrene amount of SBR can be calculated by {Σ (content of each SBR × styrene amount of each SBR)} / total content of all SBRs. For example, in 100% by mass of the rubber component, when SBR with a styrene amount of 40% by mass is 85% by mass and SBR with a styrene amount of 25% by mass is 5% by mass, the average styrene amount of SBR is 39.2% by mass (=(85×40 + 5×25) / (85 + 5)).

[0025] The vinyl bond content of SBR is preferably 3% by mass or more, more preferably 5% by mass or more, still more preferably 7% by mass or more. The vinyl bond content is preferably 25% by mass or less, more preferably 15% by mass or less, still more preferably 13% by mass or less. When it is within the above range, the effect tends to be obtained more favorably. In the present specification, the vinyl bond content (1,2-bonded butadiene unit amount) can be measured by infrared absorption spectroscopy.

[0026] The vinyl amount (1,2-bonded butadiene unit amount) of SBR is the ratio of vinyl bonds when the total mass of the butadiene part in SBR is 100 (unit: mass%), and vinyl amount [mass%] + cis amount [mass%] + trans amount [mass%] = 100 [mass%]. When there is one type of SBR, it means the vinyl amount of the SBR, and when there are multiple types, it means the average vinyl amount. The average vinyl amount of SBR can be calculated by Σ{content of each SBR × (100 [mass%] - styrene amount of each SBR [mass%]) × vinyl amount of each SBR [mass%]} / Σ{content of each SBR × (100 [mass%] - styrene amount of each SBR [mass%])}. For example, in 100 parts by mass of the rubber component, if there are 75 parts by mass of SBR with a styrene amount of 40 mass% and a vinyl amount of 30 mass%, 15 parts by mass of SBR with a styrene amount of 25 mass% and a vinyl amount of 20 mass%, and the remaining 10 parts by mass are other than SBR, the average vinyl amount of SBR is 28 mass% (={75×(100 [mass%]-40 [mass%])×30 [mass%]+15×(100 [mass%]-25 [mass%])×20 [mass%])} / {75×(100 [mass%]-40 [mass%])+15×(100 [mass%]-25 [mass%])}).

[0027] As SBR, either non-modified SBR or modified SBR can be used. Examples of the modified SBR include modified SBR into which functional groups similar to those of modified rubber are introduced. Also, as SBR, a hydrogenated styrene-butadiene copolymer (hydrogenated SBR) can also be used.

[0028] In the above rubber composition, the content of SBR in 100% by mass of the rubber component is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, and is preferably 95% by mass or less, more preferably 85% by mass or less, still more preferably 80% by mass or less. When it is within the above range, the effect tends to be preferably obtained.

[0029] The raw materials (monomers) of synthetic rubbers such as SBR and BR may be derived from petroleum, or may be recycled from rubber products such as tires and non-rubber products such as polystyrene. The monomers obtained by recycling (recycled monomers) are not particularly limited, and examples include recycled butadiene and recycled aromatic vinyl. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl is not particularly limited, and examples include styrene. Among them, it is preferable to use recycled butadiene (recycled butadiene) and / or recycled styrene (recycled styrene) as raw materials.

[0030] The method for producing recycled monomers is not particularly limited, and examples include being synthesized from recycled naphtha obtained by decomposing rubber products such as tires. Also, the method for producing recycled naphtha is not particularly limited, and for example, rubber products such as tires may be decomposed under high temperature and high pressure, decomposed by microwaves, or extracted after mechanical pulverization.

[0031] Furthermore, the raw materials (monomers) of synthetic rubbers such as SBR and BR may be derived from biomass. The monomers derived from biomass (biomass monomers) are not particularly limited, and examples include butadiene derived from biomass and aromatic vinyl derived from biomass. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl is not particularly limited, and examples include styrene. Also, the method for producing biomass monomers is not particularly limited, and examples include those by biological and / or chemical and / or physical conversion of animals and plants. Fermentation by microorganisms is typical as biological conversion, and examples of chemical and / or physical conversion include those by catalysts, high heat, high pressure, electromagnetic waves, supercritical fluids, and combinations thereof. Examples of the biomass sources of these monomers include sugars, wood, plant residues after obtaining useful components, ethanol derived from plants, biomass naphtha, and the like.

[0032] The polymers synthesized from biomass monomer components (biomass polymers) are not particularly limited, and examples include polybutadiene rubber synthesized from butadiene derived from biomass, and aromatic vinyl / butadiene copolymers synthesized from butadiene derived from biomass and / or aromatic vinyl derived from biomass. Examples of the aromatic vinyl / butadiene copolymers include styrene-butadiene rubber synthesized from butadiene derived from biomass and / or styrene derived from biomass.

[0033] Whether the raw material of the polymer is derived from biomass can be determined by pMC (percent Modern Carbon) measured in accordance with ASTM D6866-10.

[0034] pMC is the ratio of the 14 C concentration of the sample to the 14 C concentration of the standard modern carbon (modern standard reference), and this value is used as an index indicating the biomass ratio of the compound (rubber). The significance of this value will be described below.

[0035] One mole (6.02 × 10 23 atoms) of carbon atoms contains approximately 6.02 × 10 11 atoms of 14 C, which is about one trillionth of ordinary carbon atoms. 14 C is called a radioactive isotope, and its half-life is 5730 years and it decreases regularly. It takes 226,000 years for all of these to decay. Therefore, in fossil fuels such as coal, oil, and natural gas, which are considered to have passed more than 226,000 years after carbon dioxide in the atmosphere was taken up and fixed by plants, etc., all of the 14 C element has decayed. Therefore, at present in the 21st century, fossil fuels such as coal, oil, and natural gas do not contain 14 any C element at all. Therefore, chemical substances produced from these fossil fuels also do not contain 14 any C element.

[0036] On the other hand, 14 C is constantly generated by nuclear reactions of cosmic rays in the atmosphere, and is in balance with the decrease due to radioactive decay. In the earth's atmospheric environment, 14 the amount of 14 C is constant. Therefore, the -12 C concentration of substances derived from biomass resources that are circulating in the current environment is about 1 × 10

[0037] This 14 C is generally measured as follows. Using accelerator mass spectrometry based on a tandem accelerator, 13 the 13 C concentration ( 12 C / 14 C) and 14 the 12 C concentration ( 14As a modern standard reference for the concentration standard of C, the 14 C concentration in the circulating carbon in nature as of 1950 is adopted. As a specific reference substance, the oxalic acid standard provided by NIST (National Institute of Standards and Technology) is used. The specific radioactivity of carbon in this oxalic acid (the 14 radioactivity intensity of 14 C per gram of carbon) is fractionated for each carbon isotope, and 13 for 13 C, it is corrected to a constant value, and the value obtained by applying the decay correction from 1950 AD to the measurement date is used as the standard 14 14 C concentration value (100%). The ratio of this value to the value of the sample actually measured is the pMC value.

[0038] Therefore, if the rubber is made of a 100% biomass (natural-based) material, although there are regional differences, it will generally show a value of about 110 pMC (currently, in the normal state, it often does not reach 100). On the other hand, for chemical substances derived from fossil fuels such as petroleum, when this 14 14 C concentration is measured, it will show approximately 0 pMC (for example, 0.3 pMC). This value corresponds to a biomass ratio of 0% mentioned above.

[0039] From the above, using materials such as rubber with a high pMC value, that is, materials such as rubber with a high biomass ratio, in the rubber composition is suitable in terms of environmental protection.

[0040] The above rubber composition contains silica, and the silica contains biomass-derived silica.

[0041] Examples of the biomass-derived silica include plant-derived silica. Examples of the plant-derived silica include silica derived from plants containing silica content. Examples of plants containing silica include rice, corn, sugarcane, nettle, wheat, barley, rye, adlay, millet, panic grass, Japanese millet, pampas grass, and Miscanthus. In addition, saccharification residues of plants containing silica can also be used. Among these, rice husks and straw with a high silica content are preferred, and rice husks are more preferred (rice husk silica). In addition, plants containing silica may be those that have been incinerated to ash or carbonized. These may be used alone or in combination of two or more.

[0042] Silica that can be used in addition to biomass-derived silica (hereinafter also referred to as "other silica") includes dry-process silica (anhydrous silica), wet-process silica (hydrous silica), and the like. Among these, wet-process silica is preferred because of its large number of silanol groups. As commercially available products, products of Degussa, Rhodia, Tosoh Silica Corporation, Solvay Japan, Inc., Tokuyama Corporation, etc. can be used. These may be used alone or in combination of two or more.

[0043] The silica contained in the rubber composition has an average particle size A of 15 nm or less. The average particle size A of the silica is preferably 14 nm or less, more preferably 13 nm or less, and is preferably 6 nm or more, more preferably 9 nm or more, still more preferably 10 nm or more. When within the above range, the effect tends to be obtained more favorably. Note that the average particle size A of the silica is the average particle size of all types of silica (biomass-derived silica and other silica) contained in the rubber composition. The average particle size of the biomass-derived silica is preferably in the same range.

[0044] In this specification, the method for measuring the average particle diameter A of silica uses transmission electron microscope (TEM) observation. Specifically, silica particles are photographed with a transmission electron microscope. When the shape of the particles is spherical, the diameter of the sphere is taken as the particle diameter; when the shape is needle-like or rod-like, the minor axis is taken as the particle diameter; when the shape is amorphous, the average particle diameter from the center is taken as the particle diameter, and the average value of the particle diameters of 100 fine particles is taken as the average particle diameter.

[0045] The nitrogen adsorption specific surface area (N 2 SA) of silica is preferably 100 m 2 / g or more, more preferably 130 m 2 / g or more, still more preferably 150 m 2 / g or more. The upper limit is preferably 250 m 2 / g or less, more preferably 220 m 2 / g or less, still more preferably 200 m 2 / g or less. When within the above range, the effect tends to be obtained more favorably. The average particle diameter of biomass-derived silica is also preferably in the same range. In this specification, the N 2 SA of silica is a value measured by the BET method in accordance with ASTM D3037-93.

[0046] The CTAB specific surface area (cetyltrimethylammonium bromide adsorption specific surface area, CTAB) of silica is preferably 100 m 2 / g or more, more preferably 130 m 2 / g or more, still more preferably 150 m 2 / g or more. The upper limit is preferably 250 m 2 / g or less, more preferably 220 m 2 / g or less, still more preferably 200 m 2 / g or less. When within the above range, the effect tends to be obtained more favorably. The average particle diameter of biomass-derived silica is also preferably in the same range. In this specification, the CTAB specific surface area of silica is a value measured in accordance with JIS K6217-3.

[0047] In the above rubber composition, the content C of silica (total amount of biomass-derived silica and other silica) is 50 parts by mass or more, preferably 60 parts by mass or more, more preferably 70 parts by mass or more, still more preferably 80 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content C is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, still more preferably 100 parts by mass or less. When within the above range, the effect tends to be obtained more favorably.

[0048] In the above rubber composition, the content of biomass-derived silica is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, still more preferably 70 parts by mass or more, particularly preferably 80 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 150 parts by mass or less, more preferably 100 parts by mass or less, still more preferably 80 parts by mass or less. When within the above range, the effect tends to be obtained more favorably.

[0049] The biomass-derived silica content rate in 100% by mass of the silica contained in the above rubber composition is preferably 60% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, particularly preferably 100% by mass. When within the above range, the effect tends to be obtained more favorably.

[0050] The above rubber composition contains a silane coupling agent. In the above rubber composition, the content C of the above silica, the average particle diameter A of the above silica, and the average carbon number E of the above silane coupling agent satisfy the following formula (1). (1) E × A / C > 2.5 The right side of formula (1) is preferably 2.8, more preferably 3.0, still more preferably 3.1. The upper limit of E × A / C is preferably 6.0 or less, more preferably 5.0 or less, still more preferably 4.7 or less. When within the above range, the effect tends to be obtained more favorably.

[0051] The average carbon number E (the average carbon number of all silane coupling agents contained in the rubber composition) of the silane coupling agent contained in the above rubber composition is preferably 10.0 or more, more preferably 12.0 or more, still more preferably 13.0 or more, and is preferably 50.0 or less, more preferably 30.0 or less, still more preferably 20.0 or less. When it is within the above range, the effect tends to be obtained more favorably.

[0052] The carbon number of each silane coupling agent (silane coupling agent compound) used in the above rubber composition is preferably 10 or more, more preferably 12 or more, still more preferably 13 or more, and is preferably 50 or less, more preferably 30 or less, still more preferably 20 or less. When it is within the above range, the effect tends to be obtained more favorably.

[0053] In this specification, the carbon number of the silane coupling agent (silane coupling agent compound) is the total number of carbon atoms in the longest chain (skeleton) composed of a plurality of elements containing carbon in the compound of the silane coupling agent. For example, the carbon number E of the silane coupling agent (bis(3-(triethoxysilyl)propyl)tetrasulfide) represented by the following formula (A) is 10, and the carbon number E of the silane coupling agent (3-octanoylthiopropyltriethoxysilane) represented by the following formula (B) is 13.

Chemical formula

[0054] In this specification, the average carbon number E of the silane coupling agent is a value calculated by {Σ(carbon number of each silane coupling agent × content of each silane coupling agent)} / total content of all silane coupling agents. For example, when 3 parts by mass of a silane coupling agent having a carbon number of 10 and 5 parts by mass of a silane coupling agent having a carbon number of 30 are used per 100 parts by mass of the rubber component, the average carbon number E of the silane coupling agent is 22.5 (= (10×3 + 30×5) / (3 + 5)).

[0055] As the silane coupling agent, for example, a mercapto-based silane coupling agent can be preferably used.

[0056] Examples of the mercapto-based silane coupling agent include a silane coupling agent having a mercapto group and a silane coupling agent in which the mercapto group is protected. These may be used alone or in combination of two or more.

[0057] Preferable mercapto-based silane coupling agents include (i) a silane coupling agent represented by the following formula (2-1), (ii) a silane coupling agent containing a bonding unit A represented by the following formula (2-2) and a bonding unit B represented by the following formula (2-3), and the like. [Chemical formula] (In formula (2-1), R 101 is -Cl, -Br, -OR 106 , -O(O=)CR 106 , -ON=CR 106 R 107 , -NR 106 R 107 and -(OSiR 106 R 107 ) h (OSiR 106 R 107 R 108 )-selected monovalent groups (R 106 , R 107 and R 108 may be the same or different and are each a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, and h has an average value of 1 to 4.) And R 102 is R 101 , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, R 103 is -[O(R 109 O) j -group (R 109 is an alkylene group having 1 to 18 carbon atoms, and j is an integer of 1 to 4.), R 104 is a divalent hydrocarbon group having 1 to 18 carbon atoms, R 105represents a monovalent hydrocarbon group having 1 to 18 carbon atoms, and xa, ya, and za are numbers that satisfy the relationships xa + ya + 2za = 3, 0 ≦ xa ≦ 3, 0 ≦ ya ≦ 2, and 0 ≦ za ≦ 1.)

Chem.

Chem.

[0058] In R 102 , R 105 , R 106 , R 107 and R 108 in the above Formula (2-1), specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a cyclopentyl group, a cyclohexyl group, a vinyl group, a propenyl group, an allyl group, a hexenyl group, an octenyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a tolyl group, a xylyl group, a naphthyl group, a benzyl group, a phenethyl group, a naphthylmethyl group, and the like.) In R 109As an example, linear alkylene groups include a methylene group, an ethylene group, an n-propylene group, an n-butylene group, a hexylene group, etc., and branched alkylene groups include an isopropylene group, an isobutylene group, a 2-methylpropylene group, etc.

[0059] Specific examples of the silane coupling agent represented by the above formula (2-1) include 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltriethoxysilane, 3-lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane, 3-hexanoylthiopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2-octanoylthioethyltrimethoxysilane, 2-decanoylthioethyltrimethoxysilane, 2-lauroylthioethyltrimethoxysilane, etc. Among them, 3-octanoylthiopropyltriethoxysilane (NXT manufactured by Momentive) is particularly preferred. The above silane coupling agent may be used alone or in combination of two or more.

[0060] The silane coupling agent containing the bonding unit A represented by the formula (2-2) and the bonding unit B represented by the formula (2-3) suppresses the increase in viscosity during processing compared with polysulfide silanes such as bis-(3-triethoxysilylpropyl)tetrasulfide. This is presumably because the sulfide moiety of the bonding unit A is a C-S-C bond, which is thermally more stable than tetrasulfide or disulfide, resulting in less increase in Mooney viscosity.

[0061] Further, compared with mercaptosilanes such as 3-mercaptopropyltrimethoxysilane, the shortening of the scorch time is suppressed. This is because although the linking unit A has the structure of mercaptosilane, the -C 7 H 15 portion of the linking unit A covers the -SH group of the linking unit B, making it difficult to react with the polymer and less likely to cause scorch.

[0062] In the silane coupling agent having the above structure, the content of the linking unit A is preferably 30 mol% or more, more preferably 50 mol% or more, preferably 99 mol% or less, and more preferably 90 mol% or less. Also, from the viewpoint of reactivity with silica, the content of the linking unit B is preferably 1 mol% or more, more preferably 5 mol% or more, still more preferably 10 mol% or more, preferably 70 mol% or less, more preferably 65 mol% or less, and still more preferably 55 mol% or less. Further, the total content of the linking units A and B is preferably 95 mol% or more, more preferably 98 mol% or more, and particularly preferably 100 mol%. Note that the contents of the linking units A and B are amounts including the case where the linking units A and B are located at the terminals of the silane coupling agent. The form when the linking units A and B are located at the terminals of the silane coupling agent is not particularly limited as long as the units corresponding to the formulas (2-2) and (2-3) indicating the linking units A and B are formed.

[0063] R 201 Examples of the halogen of R include chlorine, bromine, and fluorine.

[0064] R 201 Examples of the branched or unbranched alkyl group having 1 to 30 carbon atoms of R include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, iso-butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, 2-ethylhexyl group, octyl group, nonyl group, decyl group, etc. The number of carbon atoms of the alkyl group is preferably 1 to 12.

[0065] R 201Examples of the branched or unbranched alkenyl group having 2 to 30 carbon atoms include vinyl group, 1-propenyl group, 2-propenyl group, 1-butenyl group, 2-butenyl group, 1-pentenyl group, 2-pentenyl group, 1-hexenyl group, 2-hexenyl group, 1-octenyl group and the like. The number of carbon atoms of the alkenyl group is preferably 2 to 12.

[0066] R 201 Examples of the branched or unbranched alkynyl group having 2 to 30 carbon atoms include ethynyl group, propynyl group, butynyl group, pentynyl group, hexynyl group, heptynyl group, octynyl group, nonynyl group, decynyl group, undecynyl group, dodecynyl group and the like. The number of carbon atoms of the alkynyl group is preferably 2 to 12.

[0067] R 202 Examples of the branched or unbranched alkylene group having 1 to 30 carbon atoms include ethylene group, propylene group, butylene group, pentylene group, hexylene group, heptylene group, octylene group, nonylene group, decylene group, undecylene group, dodecylene group, tridecylene group, tetradecylene group, pentadecylene group, hexadecylene group, heptadecylene group, octadecylene group and the like. The number of carbon atoms of the alkylene group is preferably 1 to 12.

[0068] R 202 Examples of the branched or unbranched alkenylene group having 2 to 30 carbon atoms include vinylene group, 1-propenylene group, 2-propenylene group, 1-butenylene group, 2-butenylene group, 1-pentenylene group, 2-pentenylene group, 1-hexenylene group, 2-hexenylene group, 1-octenylene group and the like. The number of carbon atoms of the alkenylene group is preferably 2 to 12.

[0069] R 202 Examples of the branched or unbranched alkynylene group having 2 to 30 carbon atoms include ethynylene group, propynylene group, butynylene group, pentynylene group, hexynylene group, heptynylene group, octynylene group, nonynylene group, decynylene group, undecynylene group, dodecynylene group and the like. The number of carbon atoms of the alkynylene group is preferably 2 to 12.

[0070] In a silane coupling agent containing a bonding unit A represented by formula (2-2) and a bonding unit B represented by formula (2-3), the total number of repetitions (xb + yb) of the number of repetitions (xb) of the bonding unit A and the number of repetitions (yb) of the bonding unit B is preferably in the range of 3 to 300. When within this range, the mercaptosilane of the bonding unit B is covered by -C 7 H 15 so that it is possible to suppress the shortening of the scorch time and ensure good reactivity with silica and rubber components.

[0071] As the silane coupling agent containing the bonding unit A represented by formula (2-2) and the bonding unit B represented by formula (2-3), for example, NXT-Z30, NXT-Z45, NXT-Z60, etc. manufactured by Momentive can be used. These may be used alone or in combination of two or more.

[0072] As the mercapto-based silane coupling agent, the silane coupling agent represented by the following formula (2-4) can also be preferably used.

[0073]

Chemical formula

[0074] R 6 ~R 8 represent a branched or unbranched alkyl group having 1 to 12 carbon atoms, a branched or unbranched alkoxy group having 1 to 12 carbon atoms, or a group represented by -O-(R 111 -O) z -R 112 R 6 ~R 8 at least one of which is preferably a group represented by -O-(R 111 -O) z -R 112 more preferably two of which are groups represented by -O-(R 111 -O) z -R 112 and one of which is a branched or unbranched alkoxy group having 1 to 12 carbon atoms.

[0075] R 6 ~R 8 Examples of the branched or unbranched alkyl group having 1 to 12 (preferably 1 to 5) carbon atoms for R

[0076] R 6 ~R 8 Examples of the branched or unbranched alkoxy group having 1 to 12 (preferably 1 to 5) carbon atoms for R

[0077] R 6 ~R8 -O-(R 111 -O) z -R 112 In -O-(R 111 -O)-R R represents a divalent hydrocarbon group having 1 to 30 carbon atoms (preferably 1 to 15 carbon atoms, more preferably 1 to 3 carbon atoms), which may be branched or unbranched.

[0078] R 111 Examples of the branched or unbranched alkylene group having 1 to 30 carbon atoms (preferably 1 to 15 carbon atoms, more preferably 1 to 3 carbon atoms) of R include methylene group, ethylene group, propylene group, butylene group, pentylene group, hexylene group, heptylene group, octylene group, nonylene group, decylene group, undecylene group, dodecylene group, tridecylene group, tetradecylene group, pentadecylene group, hexadecylene group, heptadecylene group, octadecylene group and the like.

[0079] R 111 Examples of the branched or unbranched alkenylene group having 2 to 30 carbon atoms (preferably 2 to 15 carbon atoms, more preferably 2 to 3 carbon atoms) of R include vinylene group, 1-propenylene group, 2-propenylene group, 1-butenylene group, 2-butenylene group, 1-pentenylene group, 2-pentenylene group, 1-hexenylene group, 2-hexenylene group, 1-octenylene group and the like.

[0080] R 111 Examples of the branched or unbranched alkynylene group having 2 to 30 carbon atoms (preferably 2 to 15 carbon atoms, more preferably 2 to 3 carbon atoms) of R include ethynylene group, propynylene group, butynylene group, pentynylene group, hexynylene group, heptynylene group, octynylene group, nonynylene group, decynylene group, undecynylene group, dodecynylene group and the like.

[0081] R 111 Examples of the arylene group having 6 to 30 carbon atoms (preferably 6 to 15 carbon atoms) include a phenylene group, a tolylene group, a xylylene group, and a naphthylene group.

[0082] z represents an integer of 1 to 30 (preferably 2 to 20, more preferably 3 to 7, and even more preferably 5 to 6).

[0083] R 112 R represents a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an aralkyl group having 7 to 30 carbon atoms. Among them, a branched or unbranched alkyl group having 1 to 30 carbon atoms is preferable.

[0084] R 112 Examples of the branched or unbranched alkyl group having 1 to 30 carbon atoms (preferably 3 to 25 carbon atoms, more preferably 10 to 15 carbon atoms) of R include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an iso-butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, an octadecyl group, and the like.

[0085] R 112 Examples of the branched or unbranched alkenyl group having 2 to 30 carbon atoms (preferably 3 to 25 carbon atoms, more preferably 10 to 15 carbon atoms) of R include a vinyl group, a 1-propenyl group, a 2-propenyl group, a 1-butenyl group, a 2-butenyl group, a 1-pentenyl group, a 2-pentenyl group, a 1-hexenyl group, a 2-hexenyl group, a 1-octenyl group, a decenyl group, an undecenyl group, a dodecenyl group, a tridecenyl group, a tetradecenyl group, a pentadecenyl group, an octadecenyl group, and the like.

[0086] R 112Examples of the aryl group having 6 to 30 carbon atoms (preferably 10 to 20 carbon atoms) include a phenyl group, a tolyl group, a xylyl group, a naphthyl group, a biphenyl group and the like.

[0087] R 112 Examples of the aralkyl group having 7 to 30 carbon atoms (preferably 10 to 20 carbon atoms) include a benzyl group, a phenethyl group and the like.

[0088] -O-(R 111 -O) z -R 112 Specific examples of the group represented by -O-(C 2 H 4 -O) 5 -C 11 H 23 、-O-(C 2 H 4 -O) 5 -C 12 H 25 、-O-(C 2 H 4 -O) 5 -C 13 H 27 、-O-(C 2 H 4 -O) 5 -C 14 H 29 、-O-(C 2 H 4 -O) 5 -C 15 H 31 、-O-(C 2 H 4 -O) 3 -C 13 H 27 、-O-(C 2 H 4 -O) 4 -C 13 H 27 、-O-(C 2 H 4 -O) 6 -C 13 H 27 、-O-(C 2 H 4 -O) 7 -C 13 H 27etc. Among them, -O-(C 2 H 4 -O) 5 -C 11 H 23 、-O-(C 2 H 4 -O) 5 -C 13 H 27 、-O-(C 2 H 4 -O) 5 -C 15 H 31 、-O-(C 2 H 4 -O) 6 -C 13 H 27 are preferred.

[0089] R 9 Examples of the branched or unbranched alkylene group having 1 to 6 carbon atoms (preferably 1 to 5 carbon atoms) of R include the same groups as the branched or unbranched alkylene group having 1 to 30 carbon atoms of R. 111 can be given.

[0090] Examples of the compound represented by the above formula (2-4) include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and the compound represented by the following formula (Si363 manufactured by EVONIK-DEGUSSA), etc. The compound represented by the following formula can be preferably used. These may be used alone or in combination of two or more.

Chemical formula

[0091] Examples of the silane coupling agent include sulfur-containing silane coupling agents such as bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)disulfide, bis(4-triethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide; vinyl-based silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based silane coupling agents such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane; polymer-type alkoxy oligomer type and polyfunctional type silane coupling agents; etc. These may be used alone or in combination of two or more kinds.

[0092] Among these, from the viewpoint of low fuel consumption, polymer-type alkoxy oligomer type or polyfunctional type silane coupling agents are preferred. Specifically, methoxy / ethoxy group-containing oligomer type silane coupling agents having an epoxy group (such as KR-517 manufactured by Shin-Etsu Silicone Co., Ltd.), methoxy group-containing oligomer type silane coupling agents having an epoxy group (such as KR-516 manufactured by Shin-Etsu Silicone Co., Ltd.), methoxy / ethoxy group-containing oligomer type silane coupling agents having a mercapto group (such as X-41-1805 manufactured by Shin-Etsu Silicone Co., Ltd.), methoxy group-containing oligomer type silane coupling agents having a mercapto group (such as X-41-1810 manufactured by Shin-Etsu Silicone Co., Ltd.), ethoxy group-containing polyfunctional type silane coupling agents having an amino group (such as X-12-972F manufactured by Shin-Etsu Silicone Co., Ltd.), ethoxy group-containing polyfunctional type silane coupling agents having an epoxy group (such as X-12-981S manufactured by Shin-Etsu Silicone Co., Ltd.), ethoxy group-containing polyfunctional type silane coupling agents having an epoxy group (such as X-12-984S manufactured by Shin-Etsu Silicone Co., Ltd.), methoxy group-containing polyfunctional type silane coupling agents having a mercapto group (such as X-12-1154 manufactured by Shin-Etsu Silicone Co., Ltd.), methoxy group-containing polyfunctional type silane coupling agents having an isocyanate group (such as X-12-1252 manufactured by Shin-Etsu Silicone Co., Ltd.), and the like can be mentioned.

[0093] In addition, as commercially available products of silane coupling agents, products of Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Admax Co., Ltd., Toray Dow Corning Co., Ltd., etc. can be used.

[0094] The content Sc (total amount of silane coupling agent) of the silane coupling agent contained in the above rubber composition is preferably 2 parts by mass or more, more preferably 6 parts by mass or more, and still more preferably 10 parts by mass or more with respect to 100 parts by mass of silica. Also, the above content is preferably 25 parts by mass or less, more preferably 20 parts by mass or less, and still more preferably 15 parts by mass or less. When it is below the upper limit, there is a tendency to obtain an effect commensurate with the blending amount. In addition, the content of the mercapto-based silane coupling agent is preferably in the same range.

[0095] In the above rubber composition, the content of the silane coupling agent having 10 or more carbon atoms (total amount of the silane coupling agent having 10 or more carbon atoms) is preferably 2 parts by mass or more, more preferably 6 parts by mass or more, and still more preferably 10 parts by mass or more with respect to 100 parts by mass of silica. Also, the above content is preferably 25 parts by mass or less, more preferably 20 parts by mass or less, and still more preferably 15 parts by mass or less. When it is below the upper limit, there is a tendency to obtain an effect commensurate with the blending amount. In addition, the content of the silane coupling agent having 13 to 30 carbon atoms is also preferably in the same range.

[0096] The above rubber composition may contain a filler other than silica. The filler is not particularly limited, and materials known in the rubber field can be used. For example, inorganic fillers such as carbon black, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, mica, bio char (BIO CHAR); difficult-to-disperse fillers, etc. can be mentioned. Among them, from the viewpoint of obtaining more effects, carbon-derived fillers (carbon-containing fillers) such as carbon black are preferred.

[0097] In the above rubber composition, the content of the filler (total amount of fillers such as silica and carbon black) is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, and still more preferably 65 parts by mass or more with respect to 100 parts by mass of the rubber component, and is also preferably 150 parts by mass or less, more preferably 110 parts by mass or less, and still more preferably 85 parts by mass or less. When it is within the above range, there is a tendency to obtain better effects.

[0098] In the above rubber composition, carbon black that can be used is not particularly limited, and examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. As commercial products, products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin Nippon Carbon Co., Ltd., Columbia Carbon Company, etc. can be used. These may be used alone or in combination of two or more. In addition to carbon black made from conventional mineral oil or the like as a raw material, carbon black made from biomass materials such as lignin may also be used. Further, recycled carbon black obtained by decomposing rubber products, plastic products, etc. containing carbon black such as tires may be appropriately used by substituting an equal amount for the above carbon black.

[0099] The nitrogen adsorption specific surface area (N 2 SA) of carbon black is preferably 50 m 2 / g or more, more preferably 80 m 2 / g or more, and still more preferably 100 m 2 / g or more. Also, the above N 2 SA is preferably 150 m 2 / g or less, more preferably 130 m 2 / g or less, and still more preferably 120 m 2 / g or less. When within the above range, the effect tends to be obtained more favorably. Note that the nitrogen adsorption specific surface area of carbon black is determined according to JIS K6217-2:2001.

[0100] The dibutyl phthalate absorption amount (DBP) of carbon black is preferably 40 ml / 100 g or more, more preferably 60 ml / 100 g or more, and still more preferably 70 ml / 100 g or more. Also, the above DBP is preferably 200 ml / 100 g or less, more preferably 150 ml / 100 g or less, and still more preferably 130 ml / 100 g or less. When within the above range, the effect tends to be obtained more favorably. Note that the DBP of carbon black is determined by the measurement method of JIS K6217-4:2001.

[0101] In the above rubber composition, the content of carbon black is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, and preferably 50 parts by mass or less, more preferably 30 parts by mass or less, still more preferably 10 parts by mass or less, based on 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0102] Examples of the difficult-to-disperse filler include microfibrillated plant fibers, short fiber-like cellulose, gel-like compounds, etc. Among them, microfibrillated plant fibers are preferred.

[0103] As the above microfibrillated plant fiber, cellulose microfibrils are preferred in terms of obtaining good reinforcing properties. The cellulose microfibrils are not particularly limited as long as they are derived from natural products. For example, resource biomass such as fruits, grains, and root vegetables, wood, bamboo, hemp, jute, kenaf, and pulp, paper, cloth, agricultural crop residues, food waste, and sewage sludge obtained from these as raw materials, waste biomass, unused biomass such as rice straw, wheat straw, and thinned wood, and cellulose produced by sea squirts, acetic acid bacteria, etc. These microfibrillated plant fibers may be used alone or in combination of two or more.

[0104] In this specification, cellulose microfibrils typically mean cellulose fibers having an average fiber diameter within the range of 10 μm or less, and more typically, cellulose fibers having a micro-structure with an average fiber diameter of 500 nm or less formed by the aggregation of cellulose molecules. A typical cellulose microfibril is formed, for example, as an aggregate of cellulose fibers having the above average fiber diameter.

[0105] When the above rubber composition contains a poorly dispersible filler, the content of the poorly dispersible filler is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, still more preferably 20 parts by mass or less, and particularly preferably 10 parts by mass or less. When within the above range, the effect tends to be obtained more favorably.

[0106] It is desirable that the above rubber composition contains a plasticizer. In this specification, a plasticizer is a material that imparts plasticity to the rubber component, and is a concept including both a plasticizer that is liquid (liquid state) at normal temperature (25°C) and a plasticizer that is solid at normal temperature (25°C). Examples of plasticizers include resin components, oils, liquid polymers, ester-based plasticizers, etc. These plasticizers may be derived from petroleum, may be derived from biomass, or may be derived from naphtha recycled from rubber products or non-rubber products. Also, low-molecular-weight hydrocarbon components obtained by thermally decomposing and extracting used tires and products containing various components may be used as plasticizers. These plasticizers may be used alone or in combination of two or more.

[0107] Specific examples of the above plasticizer include oils, liquid polymers, resins, etc. These may be used alone or in combination of two or more.

[0108] Examples of oils include process oils, vegetable oils, animal oils, etc. Examples of process oils include paraffinic process oils (mineral oils), naphthenic process oils, aromatic process oils, etc. Specific examples of process oils include, for example, MES (Mild Extract Solvated), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), RAE (Residual Aromatic Extract), etc. Also, process oils with a low content of polycyclic aromatic (PCA) compounds can be used for environmental protection. Examples of the low-PCA-content process oils include MES, TDAE, heavy naphthenic oils, etc. From the perspective of life cycle assessment, it is also possible to use waste oils after being used in rubber mixers or engines, or refined waste cooking oils used in restaurants.

[0109] In this specification, vegetable oils include, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grape seed oil, wood wax, etc. Furthermore, vegetable oils include refined oils (such as salad oil) obtained by refining the above oils, transesterified oils obtained by transesterifying the above oils, hydrogenated oils obtained by hydrogenating the above oils, thermally polymerized oils obtained by thermally polymerizing the above oils, oxidation-polymerized oils obtained by oxidizing the above oils, waste cooking oils recovered from those used as edible oils, etc. Note that vegetable oils may be liquid or solid at normal temperature (25°C). These vegetable oils may be used alone or in combination of two or more.

[0110] The vegetable oil according to this embodiment preferably contains acylglycerol, and more preferably contains triacylglycerol. In this specification, acylglycerol refers to a compound in which a hydroxy group of glycerin and a fatty acid are ester-bonded. The acylglycerol is not particularly limited, and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Further, the acylglycerol may be a monomer, a dimer, or a multimer of trimer or higher. Note that acylglycerols of dimer or higher can be obtained by thermal polymerization, oxidative polymerization, or the like. Also, the acylglycerol may be liquid or solid at room temperature (25°C).

[0111] As a method for confirming whether the acylglycerol is contained in the rubber composition, it is not particularly limited, but 1 it can be confirmed by 1H-NMR measurement. For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at room temperature (25°C) for 24 hours. After removing the rubber composition, 1 1H-NMR is measured. When the signal of tetramethylsilane (TMS) is set to 0.00 ppm, signals around 5.26 ppm, around 4.28 ppm, and around 4.15 ppm are observed, and these signals are presumed to be signals derived from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group. In this paragraph, "around" means a range of ±0.10 ppm.

[0112] The fatty acid is not particularly limited, and may be an unsaturated fatty acid or a saturated fatty acid. Examples of the unsaturated fatty acid include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. Examples of the saturated fatty acid include butyric acid and lauric acid.

[0113] Among these, as the fatty acid, it is desirable to contain a fatty acid with few double bonds, that is, a saturated fatty acid or a monounsaturated fatty acid, and oleic acid is preferred. As the vegetable oil containing such a fatty acid, for example, a vegetable oil containing a saturated fatty acid or a monounsaturated fatty acid may be used, or a vegetable oil subjected to modification such as transesterification may be used. Further, in order to produce a vegetable oil containing such a fatty acid, plants may be improved by variety improvement, genetic recombination, genome editing, or the like.

[0114] As the oil, for example, those commercially available from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Co., Ltd., Olisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kogyo Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0115] Examples of the liquid polymer include a liquid diene polymer (liquid rubber) and a liquid farnesene polymer at 25°C. Examples of the liquid rubber include a liquid styrene-butadiene copolymer (liquid SBR), a liquid butadiene polymer (liquid BR), a liquid isoprene polymer (liquid IR), a liquid styrene-isoprene copolymer (liquid SIR), a liquid styrene-butadiene-styrene block copolymer (liquid SBS block polymer), a liquid styrene-isoprene-styrene block copolymer (liquid SIS block polymer), etc. These may have their terminals or main chains modified with polar groups. Also, hydrogenated products thereof can be used.

[0116] The above liquid diene polymer preferably has a polystyrene-reduced weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) of 1.0×10 3 or more, more preferably 3.0×10 3 or more, and preferably 5.0×10 4 or less, more preferably 1.5×10 4 or less. Also, the lower limit or upper limit of Mw of the liquid diene polymer may be 4500 or 8500. In this specification, the Mw of the liquid diene polymer is a polystyrene equivalent value measured by gel permeation chromatography (GPC).

[0117] As the above liquid diene polymer, for example, products of Sartomer Co., Kuraray Co., Ltd. etc. can be used.

[0118] As the above resin, as a tire compounding material, resins (resins) commonly used can be used, and they may be liquid or solid at normal temperature (25°C). For example, aromatic vinyl polymers, coumarone-indene resins, coumarone resins, indene resins, phenolic resins, rosin resins, petroleum resins, terpene resins, acrylic resins, etc. can be mentioned. Also, the resin may be a hydrogenated resin (hydrogenated resin). These may be used alone or in combination of two or more. Also, the resin itself may be a copolymer of monomer components from a plurality of sources. Among them, aromatic vinyl polymers, petroleum resins, terpene resins, and hydrogenated resins thereof are desirable.

[0119] When using a resin that is solid at normal temperature, the softening point of the above resin is preferably 50°C or higher, more preferably 55°C or higher, still more preferably 60°C or higher, and particularly preferably 85°C or higher. Also, it is preferably 160°C or lower, more preferably 150°C or lower, still more preferably 140°C or lower, and particularly preferably 100°C or lower. When within the above range, the effect tends to be obtained more favorably. When the resin is liquid at normal temperature, the softening point is preferably 20°C or lower, preferably 10°C or lower, and preferably 0°C or lower. In the case of a hydrogenated resin, it is desirable that the softening point is the same as above. Note that the softening point of the above resin is measured with a ring and ball softening point measuring device for the softening point defined in JIS K6220-1:2001, and is the temperature at which the ball drops.

[0120] The above aromatic vinyl polymer is a polymer containing an aromatic vinyl monomer as a constituent unit. For example, resins obtained by polymerizing α-methylstyrene and / or styrene can be mentioned. Specifically, homopolymers of styrene (styrene resins), homopolymers of α-methylstyrene (α-methylstyrene resins), copolymers of α-methylstyrene and styrene, copolymers of styrene and other monomers, etc. can be mentioned.

[0121] The above coumarone-indene resin is a resin containing coumarone and indene as the main monomer components constituting the resin skeleton (main chain). As monomer components contained in the skeleton other than coumarone and indene, styrene, α-methylstyrene, methyl indene, vinyl toluene, etc. can be mentioned.

[0122] The above coumarone resin is a resin containing coumarone as the main monomer component constituting the resin skeleton (main chain).

[0123] The above indene resin is a resin containing indene as the main monomer component constituting the resin skeleton (main chain).

[0124] As the above phenol resin, for example, known ones such as polymers obtained by reacting phenol with aldehydes such as formaldehyde, acetaldehyde, and furfural in the presence of an acid or alkali catalyst can be used. Among them, those obtained by reacting with an acid catalyst (such as novolak-type phenol resins) are preferred.

[0125] Examples of the above rosin resin include rosin-based resins typified by natural rosin, polymerized rosin, modified rosin, ester compounds thereof, and hydrogenated products thereof.

[0126] Examples of the above petroleum resin include C5-based resins, C9-based resins, C5 / C9-based resins, dicyclopentadiene (DCPD) resins, C9 / DCPD resins, and hydrogenated products thereof. Among them, DCPD resins, hydrogenated DCPD resins, C9 / DCPD resins, and C9 / hydrogenated DCPD resins are preferred.

[0127] The above terpene resin is a polymer containing terpenes as constituent units. For example, there are polyterpene resins obtained by polymerizing terpene compounds, aromatic modified terpene resins obtained by polymerizing terpene compounds and aromatic compounds, and the like. Examples of aromatic modified terpene resins include terpene phenol resins using terpene compounds and phenolic compounds as raw materials, terpene styrene resins using terpene compounds and styrene compounds as raw materials, and terpene phenol styrene resins using terpene compounds, phenolic compounds and styrene compounds as raw materials. Examples of terpene compounds include α-pinene, β-pinene, etc., examples of phenolic compounds include phenol, bisphenol A, etc., and examples of aromatic compounds include styrene compounds (styrene, α-methylstyrene, etc.). Among them, aromatic modified terpene resins are preferred.

[0128] The above acrylic resin is a polymer containing acrylic monomers as constituent units. For example, there are styrene acrylic resins such as styrene acrylic resins obtained by copolymerizing an aromatic vinyl monomer component and an acrylic monomer component and having a carboxyl group. Among them, a solvent-free carboxyl group-containing styrene acrylic resin can be preferably used.

[0129] Examples of the above resins include products of Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical, ExxonMobil, KRATON, Nippon Paint Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Co., Ltd., Arakawa Chemical Industries, Ltd., Tago Chemical Industry Co., Ltd., etc.

[0130] From the perspective of sustainability, it is desirable to use plant-derived plasticizers such as the above plant-derived oils and farnesene-based polymers as the above plasticizers.

[0131] The farnesene-based polymer is a polymer obtained by polymerizing farnesene and has a structural unit based on farnesene. Farnesene has isomers such as α-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecatetraene) and β-farnesene (7,11-dimethyl-3-methylene-1,6,10-dodecatriene), but (E)-β-farnesene having the following structure is preferred. [Chemical formula]

[0132] The farnesene-based polymer may be a homopolymer of farnesene (farnesene homopolymer) or a copolymer of farnesene and a vinyl monomer (farnesene-vinyl monomer copolymer). These may be used alone or in combination of two or more. Among them, a copolymer of farnesene and a vinyl monomer is preferred.

[0133] Examples of vinyl monomers include aromatic vinyl compounds such as styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-tert-butylstyrene, 5-t-butyl-2-methylstyrene, vinyl ethylbenzene, divinylbenzene, trivinylbenzene, divinylnaphthalene, tert-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl)dimethylaminoethyl ether, N,N-dimethylaminoethylstyrene, N,N-dimethylaminomethylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-t-butylstyrene, 3-t-butylstyrene, 4-t-butylstyrene, vinylxylene, vinylnaphthalene, vinyltoluene, vinylpyridine, diphenylethylene, and tertiary amino group-containing diphenylethylene, and conjugated diene compounds such as butadiene and isoprene. These may be used alone or in combination of two or more. Among them, butadiene is preferred. That is, as the farnesene-vinyl monomer copolymer, a copolymer of farnesene and butadiene (farnesene-butadiene copolymer) is preferred.

[0134] In the farnesene-vinyl monomer copolymer, the copolymerization ratio (farnesene / vinyl monomer) based on the mass of farnesene and the vinyl monomer is preferably 40 / 60 to 90 / 10.

[0135] Farnesene-based polymers with a weight average molecular weight (Mw) of 3000 or more and 300,000 or less can be preferably used. The Mw of the farnesene-based polymer is preferably 8000 or more, more preferably 10000 or more, and preferably 100,000 or less, more preferably 60,000 or less, and even more preferably 50,000 or less. When within the above range, the effects tend to be more preferably obtained.

[0136] The farnesene-based polymer may be in a liquid state or a solid state at room temperature (25°C). Among them, a liquid farnesene-based polymer in a liquid state at room temperature (25°C) is desirable.

[0137] In the above rubber composition, the content of the plasticizer (total amount of the plasticizer) is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, still more preferably 10 parts by mass or less, based on 100 parts by mass of the rubber component. The upper limit is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, still more preferably 8 parts by mass or more. When it is within the above range, the effect tends to be obtained more favorably. Note that the content of the plasticizer includes the amount of oil and resin contained in the oil-extended rubber and resin-extended rubber.

[0138] In the above rubber composition, the content of the solid plasticizer in a solid state at room temperature (25 °C) is preferably 30 parts by mass or less, more preferably 10 parts by mass or less, still more preferably 5 parts by mass or less, based on 100 parts by mass of the rubber component, and may be 0 parts by mass. When it is within the above range, the effect tends to be obtained more favorably. Note that the content of the resin in a solid state at room temperature (25 °C) is preferably in the same range.

[0139] In the above rubber composition, the content of the liquid plasticizer in a liquid state at room temperature (25 °C) is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, still more preferably 10 parts by mass or less, based on 100 parts by mass of the rubber component. The upper limit is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, still more preferably 8 parts by mass or more. When it is within the above range, the effect tends to be obtained more favorably. Note that the content of the liquid plasticizer includes the amount of oil contained in the oil-extended rubber and the amount of liquid resin of the resin-extended rubber extended with the liquid resin. The content of the oil in a liquid state at room temperature (25 °C) is preferably in the same range.

[0140] From the viewpoint of obtaining more effects, the above rubber composition preferably contains a compound represented by the following formula (I). The compound represented by the formula (I) may be used alone or in combination of two or more.

Chemical formula

[0141] R 1 ~R 3 The hydrocarbon groups of R

[0142] ~R

[0143] may be linear, branched, or cyclic, and examples include aliphatic hydrocarbon groups, alicyclic hydrocarbon groups, aromatic hydrocarbon groups, etc. Among them, aliphatic hydrocarbon groups are preferred. The carbon number of the hydrocarbon group is preferably 1 or more, more preferably 5 or more, still more preferably 8 or more, particularly preferably 12 or more, and preferably 30 or less, more preferably 25 or less, still more preferably 22 or less, particularly preferably 20 or less. When within the above range, the effect tends to be more preferably obtained.

[0142] Examples of the aliphatic hydrocarbon group include an alkyl group, an alkylene group, an alkenyl group, an alkenylene group, an alkynyl group, an alkynylene group, etc. Among them, the alkyl group having the above carbon number is preferred. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, an octadecyl group, etc.

[0143] As the alicyclic hydrocarbon group, those having 3 to 8 carbon atoms are preferred. Specifically, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclopropenyl group, cyclobutenyl group, cyclopentenyl group, cyclohexenyl group, cycloheptenyl group, cyclooctenyl group and the like can be mentioned.

[0144] As the aromatic hydrocarbon group, those having 6 to 10 carbon atoms are preferred. Specifically, phenyl group, benzyl group, phenethyl group, tolyl group, xylyl group, naphthyl group and the like can be mentioned. In the tolyl group and xylyl group, the substitution position of the methyl group on the benzene ring may be any of the ortho position, meta position and para position.

[0145] R 2 、R 3 's -(AO) n -H group (n represents an integer of 1 or more, and each n of R 2 、R 3 may be the same or different from each other.) The AO represents an oxyalkylene group having 2 or more carbon atoms. The number of carbon atoms is preferably 3 or more, and the upper limit is not particularly limited, but is preferably 7 or less, more preferably 6 or less, and still more preferably 5 or less. When within the above range, the effect tends to be more suitably obtained.

[0146] The alkylene group A in the oxyalkylene group AO may be either linear or branched. For the reason that the effect is more suitably obtained, AO is preferably a group in which a branched chain R 4 (R 4 represents a hydrocarbon group.) is bonded to an oxyalkylene group having 2 to 3 carbon atoms (oxyethylene group (EO), oxypropylene group (PO)). The -(AO) n -H group is more preferably a group represented by the following formulas (A) and (B), and still more preferably a group represented by the following formula (A). Further, the branched chain R 4 is preferably bonded to the carbon atom adjacent to the oxygen atom. [Chemical formula] (In formulas (A) and (B), R 4 represents a hydrocarbon group. n is -(AO) n -H group is the same as n of the -H group.)

[0147] R 4 's hydrocarbon group is the same as the hydrocarbon group of R 1 ~ R 3 's hydrocarbon group. Among them, an aliphatic hydrocarbon group is preferable, and an alkyl group is more preferable. The number of carbon atoms of the hydrocarbon group (preferably an aliphatic hydrocarbon group, more preferably an alkyl group) is preferably 1 or more, more preferably 2 or more, preferably 6 or less, more preferably 5 or less, still more preferably 4 or less, and particularly preferably 3 or less. When within the above range, the effect tends to be more preferably obtained.

[0148] (AO) n contains two or more kinds of oxyalkylene groups, the arrangement of the oxyalkylene groups may be block or random.

[0149] n represents the number of moles of addition of AO. n is preferably 1 or more, more preferably 2 or more, preferably 20 or less, more preferably 16 or less, still more preferably 10 or less, particularly preferably 5 or less, and most preferably 3 or less. When within the above range, the effect tends to be more preferably obtained.

[0150] In formula (I), at least one of R 2 , R 3 is a -(AO) n -H group, but it is more preferable that all of R 2 , R 3 are -(AO) n -H groups. That is, the compound represented by the above formula (I) is more preferably a compound represented by the following formula (I-1). Thereby, the effect tends to be more preferably obtained. [Chemical formula] (Except for the case where n1 and n2 in the formula (I-1) represent integers of 1 or more (the same integers as n), it is the same as the formula (I).)

[0151] In the formulas (I) and (I-1), the total number of moles of addition of AO (n1 + n2) is preferably 2 or more, more preferably 3 or more, still more preferably 4 or more, preferably 40 or less, more preferably 32 or less, still more preferably 20 or less, particularly preferably 10 or less, and most preferably 6 or less. When within the above range, the effect tends to be more preferably obtained.)

[0152] Specific examples of the compound represented by the formula (I) include, for example, liponols manufactured by Lion Specialty Chemicals Co., Ltd. (in the formula (I), R 2 :-(CH 2 CH 2 )x-H, R 3 :-(CH 2 CH 2 )y-H), etc. These may be used alone or in combination of two or more.)

[0153] Specific examples of the compound represented by the above formula (I-1) include, for example, POE(2) octylamine, POE(4) decylamine, POE(2) dodecylamine, POE(5) dodecylamine, POE(15) dodecylamine, POE(2) tetradecylamine, POE(2) hexadecylamine, POE(2) octadecylamine, POE(20) octadecylamine, POE(2) octadecenylamine, etc. Note that POE(m) indicates that polyoxyethylene is added in an average of m moles. As commercially available products, Amite 102 (POE(2) dodecylamine), Amite 105 (POE(5) dodecylamine), Amite 302 (POE(2) octadecylamine), Amite 320 (POE(20) octadecylamine), etc. manufactured by Kao Corporation can be used.)

[0154] As the compound represented by the formula (I), the above-mentioned commercially available products or the like may be used, or those produced separately from these commercially available products or the like may be used. As a production method, for example, it is conceivable to allow an alkylene oxide to act on a polyvalent amine compound in the presence or absence of a catalyst, but the method is not limited thereto.

[0155] In the above rubber composition, the content of the compound represented by the formula (I) is preferably 0.1 part by mass or more, more preferably 0.2 part by mass or more, based on 100 parts by mass of the rubber component. Further, the content is preferably 10.0 parts by mass or less, more preferably 8.0 parts by mass or less, still more preferably 6.0 parts by mass or less, based on 100 parts by mass of the rubber component. When the content of the compound is within the above range, the effect can be obtained more suitably.

[0156] From the viewpoints of crack resistance, ozone resistance, etc., the above composition preferably contains an antioxidant.

[0157] The anti-aging agent is not particularly limited, but examples include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; p-phenylenediamine-based anti-aging agents such as N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-ditoly-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline-based anti-aging agents such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based anti-aging agents such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; bis, tris, polyphenol-based anti-aging agents such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among them, p-phenylenediamine-based anti-aging agents and quinoline-based anti-aging agents are preferred, and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and polymers of 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. As commercially available products, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinsei Chemical Industry Co., Ltd., Flexsys Co., Ltd. can be used.

[0158] In the above rubber composition, the content of the anti-aging agent is preferably 0.2 parts by mass or more, more preferably 2.0 parts by mass or more, still more preferably 2.5 parts by mass or more, based on 100 parts by mass of the rubber component. The content is preferably 7.0 parts by mass or less, more preferably 3.5 parts by mass or less.

[0159] The above rubber composition preferably contains stearic acid. In the above rubber composition, the content of stearic acid is preferably 0.5 parts by mass or more, more preferably 2.0 parts by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, based on 100 parts by mass of the rubber component.

[0160] As the stearic acid, conventionally known ones can be used. For example, products of NOF Corporation, Kao Corporation, FUJIFILM Wako Pure Chemical Corporation, Chiba Fatty Acids Co., Ltd., etc. can be used.

[0161] The above rubber composition preferably contains zinc oxide. In the above rubber composition, the content of zinc oxide is preferably 0.5 parts by mass or more, more preferably 2.0 parts by mass or more, and preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, based on 100 parts by mass of the rubber component.

[0162] As the zinc oxide, conventionally known ones can be used. For example, products of Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusuitech Co., Ltd., Sho-Doh Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used.

[0163] The above rubber composition may be blended with wax. In the above rubber composition, the content of wax is preferably 1.0 parts by mass or more, more preferably 2.0 parts by mass or more, and preferably 10.0 parts by mass or less, more preferably 5.0 parts by mass or less, based on 100 parts by mass of the rubber component.

[0164] The wax is not particularly limited, and examples include petroleum waxes and natural waxes. Synthetic waxes obtained by refining or chemically treating a plurality of waxes can also be used. These waxes may be used alone or in combination of two or more.

[0165] Examples of petroleum waxes include paraffin wax and microcrystalline wax. Natural waxes are not particularly limited as long as they are waxes derived from non-petroleum resources. For example, plant waxes such as candelilla wax, carnauba wax, wood wax, rice wax, and jojoba wax; animal waxes such as beeswax, lanolin, and sperm whale wax; mineral waxes such as ozokerite, ceresin, and petrolactam; and refined products thereof. As commercially available products, for example, products of Ouchi Shinsei Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Seiko Chemical Co., Ltd., etc. can be used.

[0166] In the above rubber composition, it is preferable to compound sulfur in terms of forming appropriate crosslinked chains in the polymer chain and imparting good performance.

[0167] In the above rubber composition, the sulfur content is preferably 0.5 parts by mass or more, more preferably 1.5 parts by mass or more, still more preferably 2.0 parts by mass or more, based on 100 parts by mass of the rubber component. The content is preferably 7.0 parts by mass or less, more preferably 5.0 parts by mass or less, still more preferably 4.0 parts by mass or less.

[0168] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, soluble sulfur, etc., which are generally used in the rubber industry. As commercially available products, products of Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexsys, Nippon Karyu Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

[0169] The above rubber composition preferably contains a vulcanization accelerator. In the above rubber composition, the content of the vulcanization accelerator is not particularly limited and may be freely determined according to the desired vulcanization rate and crosslink density. However, based on 100 parts by mass of the rubber component, it is preferably 3.0 parts by mass or more, more preferably 5.0 parts by mass or more, still more preferably 5.3 parts by mass or more. The upper limit is preferably 8.0 parts by mass or less, more preferably 7.0 parts by mass or less, still more preferably 6.0 parts by mass or less.

[0170] In the above rubber composition, the content of the vulcanization accelerator is not particularly limited and may be freely determined according to the desired vulcanization rate and crosslink density. However, it is preferably 2.0 parts by mass or more, more preferably 4.0 parts by mass or more, and still more preferably 4.9 parts by mass or more with respect to 100 parts by mass of the rubber component. The upper limit is preferably 8.0 parts by mass or less, more preferably 7.0 parts by mass or less, and still more preferably 6.0 parts by mass or less.

[0171] The type of the vulcanization accelerator is not particularly limited, and those commonly used can be used. Examples of the vulcanization accelerator include benzothiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyldisulfide, and N-cyclohexyl-2-benzothiazylsulfenamide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, N-t-butyl-2-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, diorthotolylguanidine, and orthotolylbiguanidine. These may be used alone or in combination of two or more. Among them, sulfenamide-based, guanidine-based, and benzothiazole-based vulcanization accelerators are preferred.

[0172] In addition to the above components, the above rubber composition may be appropriately blended with compounding agents generally used in the tire industry, such as materials such as mold release agents.

[0173] In this specification, various materials containing carbon atoms (such as rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from carbon dioxide in the atmosphere. As a method for obtaining the formulation of the present invention from carbon dioxide, carbon dioxide may be directly converted, or methane obtained through the methanation process of synthesizing methane from carbon dioxide may be converted.

[0174] The above rubber composition can be produced, for example, by kneading the above components using a rubber kneading device such as an open roll or a Banbury mixer, and then vulcanizing.

[0175] As the kneading conditions, in the base kneading step of kneading additives other than the crosslinking agent (vulcanizing agent) and the vulcanization accelerator, the kneading temperature is preferably 100 °C or higher, more preferably 120 °C or higher, and preferably 180 °C or lower, more preferably 170 °C or lower. In the finishing kneading step of kneading the vulcanizing agent and the vulcanization accelerator, the kneading temperature is preferably 80 °C or higher, and preferably 120 °C or lower, more preferably 110 °C or lower. Further, the composition kneaded with the vulcanizing agent and the vulcanization accelerator is usually subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is preferably 140 °C or higher, more preferably 150 °C or higher, and preferably 190 °C or lower, more preferably 185 °C or lower.

[0176] The above rubber composition can be applied (as a rubber composition for tires) to tire members such as cap treads, sidewalls, base treads, undertreads, clinches, bead apexes, breaker cushion rubbers, carcass cord coatings, insulations, chafers, inner liners, etc., and side reinforcement layers of run-flat tires. Among them, it is preferably used for cap treads.

[0177] The tire of the present invention is manufactured by a conventional method using the above rubber composition. That is, a composition blended with various additives as required is extruded into the shape of various tire members such as a cap tread at the unvulcanized stage, formed by a conventional method on a tire molding machine, bonded together with other tire members to form an unvulcanized tire, and then heated and pressurized in a vulcanizer to manufacture the tire.

[0178] The above tire is not particularly limited, and examples thereof include pneumatic tires, solid tires, airless tires, etc. Among them, pneumatic tires are preferred.

[0179] The above tire is preferably used as a passenger car tire, a large passenger car tire, a large SUV tire, a truck / bus tire, a motorcycle tire, a racing tire, a winter tire (a studless tire, a snow tire, a studded tire), an all-season tire, a run-flat tire, an aircraft tire, a mining tire, etc.

[0180] The above tire preferably has a cap tread made of the above rubber composition.

[0181] In the above tire, the thickness Tc (mm) of the cap tread is preferably 2.0 mm or more, more preferably 3.0 mm or more, still more preferably 4.0 mm or more, and preferably 10.0 mm or less, more preferably 9.0 mm or less, still more preferably 8.0 mm or less. When within the above range, the effect tends to be preferably obtained.

[0182] In this specification, the cap tread is a rubber layer that forms the outermost layer in the tire radial direction among the rubber layers constituting the tread. When the tread is a single-layer structure tread, it is the tread itself of the single-layer structure. When the tread is a two-layer structure tread of a cap tread and a base tread, it is the rubber layer that forms the surface layer. When the tread has a structure of three or more layers, the rubber layer that forms the outermost layer corresponds to the cap tread, respectively.

[0183] The cap tread thickness Tc refers to the thickness of the cap tread on the tire equatorial plane in the radial cross-section of the tire, and in the radial cross-section of the tire, it is the straight-line distance from the tread surface (the surface of the cap tread) to the inner surface of the cap tread in the radial direction of the tire.

[0184] The thickness of the cap tread on the tire equatorial plane is the respective value measured along the tire equatorial plane from the outermost surface of the cap tread and the outermost surface of the base tread on the tire equatorial plane. When there is an energizing member or the like on the tire equatorial plane, it is the value measured along the tire equatorial plane from the straight line connecting the ends of the interface blocked by the energizing member. When there is a groove on the tire equatorial plane, it is the thickness measured at the center in the tire width direction of the land portion closest to the tire equatorial plane, and is the thickness measured in the normal direction of the outer surface of the cap tread in the radial direction of the tire and the outer surface of the base tread in the radial direction of the tire.

[0185] In the above tire, the groove depth D (mm) of the circumferential groove formed in the tread is preferably 3.5 mm or more, more preferably 4.0 mm or more, still more preferably 4.5 mm or more, and is preferably 8.5 mm or less, more preferably 8.0 mm or less, still more preferably 7.5 mm or less. When within the above range, the effect tends to be obtained better.

[0186] In this specification, the groove depth D of the circumferential groove means the distance measured along the normal line of the plane formed by extending the grounding surface of the outermost surface of the tread from the deepest groove bottom to the plane formed by extending the grounding surface, and refers to the maximum distance among the groove depths of the provided circumferential grooves.

[0187] In the above tire, the ratio (Sc / Tc) of the content Sc (parts by mass) of the silane coupling agent to 100 parts by mass of the rubber component in the rubber composition for the cap tread and the thickness Tc (mm) of the cap tread is preferably 0.6 or more, more preferably 0.8 or more, still more preferably 1.0 or more. The upper limit is preferably 2.5 or less, more preferably 2.2 or less, still more preferably 2.0 or less. When within the above range, the effect tends to be suitably obtained.

[0188] When Sc / Tc is adjusted to a predetermined value or more, the mechanism by which a more remarkable effect is obtained is not clear, but it is considered that the hydrophobization by the silane coupling agent becomes good and the heat generation property decreases. Therefore, it is presumed that the low fuel consumption property is improved.

[0189] In the above tire, the ratio (Sc / D) of the content Sc (parts by mass) of the silane coupling agent to 100 parts by mass of the rubber component in the rubber composition for the cap tread and the groove depth D (mm) of the circumferential groove formed in the tread is preferably 0.7 or more, more preferably 0.9 or more, still more preferably 1.0 or more. The upper limit is preferably 2.5 or less, more preferably 2.2 or less, still more preferably 2.0 or less. When within the above range, the effect tends to be suitably obtained.

[0190] When Sc / D is adjusted to a predetermined value or more, the mechanism by which a more remarkable effect is obtained is not clear, but it is considered that the hydrophobization by the silane coupling agent becomes good and the heat generation property decreases. Therefore, it is presumed that the low fuel consumption property is improved.

[0191] In this specification, dimensions such as thickness are measured with the bead portion of the tire adjusted to the normal rim width. At the time of measurement, the tire is cut out in the tire radial direction, and both bead end portions of the sample are fixed in a state where they are adjusted to the width of the normal rim.

[0192] In this specification, unless otherwise specified, the dimensions of each part of the tire are values measured in the normal state. In this specification, the "normal state" refers to a no-load state in which the tire is mounted on a normal rim (not shown) and filled with the normal internal pressure.

[0193] When it cannot be measured in the state where the tire is mounted on the normal rim, the dimensions and angles of each part in the meridian cross-section of the tire are measured in the cross-section of the tire obtained by cutting the tire along the plane including the rotation axis, by making the distance between the left and right beads coincide with the distance between the beads in the tire mounted on the normal rim.

[0194] The "normal rim" is the rim defined for each tire in the standard system including the standard based on the tire. For example, in JATMA, it means the standard rim, in TRA, it means "Design Rim", or in ETRTO, it means "Measuring Rim". The "normal internal pressure" is the air pressure defined for each tire by the above standard. In JATMA, it is the maximum air pressure, in TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", and in ETRTO, it refers to "INFLATION PRESSURE". The "normal load" is the load defined for each tire by the above standard. In JATMA, it is the maximum load capacity, in TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", and in ETRTO, it means "LOAD CAPACITY".

[0195] Hereinafter, an example of the tire of the present invention will be described with reference to the drawings, but the present invention is not limited to such a form.

[0196] In FIG. 1, the vertical direction is the radial direction of the tire 2, the horizontal direction is the axial direction of the tire 2, and the direction perpendicular to the paper surface is the circumferential direction of the tire 2. The tire 2 is symmetric about the left and right. The tread 4 includes a cap layer 30 (cap tread) and a base layer 28 (base tread).

[0197] In FIG. 1, an example of a two-layer tread 4 composed of a cap layer 30 and a base layer 28 is shown, but a single-layer tread or a tread having a structure of three or more layers may also be used.

[0198] In the tire 2 of FIG. 1, it is desirable that the cap layer 30 is composed of the above rubber composition. In this case, the cap layer 30 contains a rubber component, silica, and a silane coupling agent, the content C of the silica with respect to 100 parts by mass of the rubber component is 50 parts by mass or more, the average particle diameter A of the silica is 15 nm or less, the content C of the silica, the average particle diameter A of the silica, and the average carbon number E of the silane coupling agent satisfy the formula (1) "E×A / C>2.5", and further the silica contains biomass-derived silica.

[0199] In the tire 2, each sidewall 6 extends substantially inward in the radial direction from the end of the tread 4. The outer portion of the sidewall 6 in the radial direction is joined to the tread 4. The inner portion of the sidewall 6 in the radial direction is joined to the clinch 10. This sidewall 6 can prevent damage to the carcass 14.

[0200] Each wing 8 in FIG. 1 is located between the tread 4 and the sidewall 6. The wing 8 is joined to each of the tread 4 and the sidewall 6.

[0201] Each clinch 10 is located substantially inside the sidewall 6 in the radial direction and has a portion that contacts the rim at at least one location.

[0202] The carcass 14 includes a carcass ply 36. In this tire 2, the carcass 14 is composed of a single carcass ply 36, but it may also be composed of two or more plies.

[0203] In this tire 2, the carcass ply 36 is stretched between the bead cores 32 on both sides and runs along the tread 4 and the sidewall 6. The carcass ply 36 is folded back from the axial inner side to the outer side around each bead core 32. Due to this folding, a main part 36a and a pair of folded parts 36b are formed on the carcass ply 36. That is, the carcass ply 36 includes the main part 36a and the pair of folded parts 36b.

[0204] Each bead core 32 is provided with a bead apex 34 that extends radially outward from this bead core 32. The bead core 32 is ring-shaped and preferably includes a wound non-stretchable wire. The bead apex 34 tapers radially outward.

[0205] Although not shown in the figure, the carcass ply 36 preferably consists of a large number of parallel cords and topping rubber. The absolute value of the angle formed by each cord with respect to the equatorial plane CL is preferably 75° to 90°. In other words, this carcass 14 preferably has a radial structure.

[0206] The belt layer 16 in FIG. 1 is located radially inside the tread 4. The belt layer 16 is laminated with the carcass 14. The belt layer 16 reinforces the carcass 14. In the tire 2 of FIG. 1, the belt layer 16 consists of an inner layer 38 and an outer layer 40. As is clear from FIG. 1, in the axial direction, it is desirable that the width of the inner layer 38 is slightly larger than the width of the outer layer 40. In this tire 2, the axial width of the belt layer 16 is preferably not less than 0.6 times and not more than 0.9 times the cross-sectional width of the tire 2.

[0207] Each of the inner layer 38 and the outer layer 40 preferably consists of a large number of parallel single-wire steel cords (steel monofilaments) and topping rubber (coating rubber). In other words, the belt layer 16 includes a large number of parallel steel monofilaments.

[0208] The band 18 in FIG. 1 is located radially outside the belt layer 16. In the axial direction, the band 18 has a width equal to the width of the belt layer 16. This band 18 may have a width larger than the width of the belt layer 16.

[0209] Although not shown, the band 18 preferably consists of cords and topping rubber. The cords are wound spirally. This band 18 has a so-called jointless structure. The cords extend substantially in the circumferential direction. The angle of the cords with respect to the circumferential direction is preferably 5° or less, more preferably 2° or less. Since the belt layer 16 is restrained by these cords, lifting of the belt layer 16 is suppressed.

[0210] The belt layer 16 and the band 18 in FIG. 1 constitute a reinforcing layer. The reinforcing layer may be constituted only by the belt layer 16.

[0211] FIG. 2 is an enlarged view near the tread 4 in FIG. 1. The tire in FIG. 2 is a tire 2 having a groove 26 on the tire equatorial plane (CL). In this case, the cap tread thickness (Tc) is the thickness measured at the center in the tire width direction of the land portion closest to the groove 26 on the tire equatorial plane in the radial cross section of the tire, and is the thickness measured in the normal direction of the surface of the cap layer 30 (cap tread), specifically, the linear distance in the normal direction from the outer surface of the cap layer 30 in the tire radial direction to the interface on the outermost surface side of the tire of the base layer 28.

[0212] The inner liner 20 is located inside the carcass 14. The inner liner 20 is joined to the inner surface of the carcass 14. A typical base rubber of the inner liner 20 is butyl rubber or halogenated butyl rubber. The inner liner 20 retains the internal pressure of the tire 2.

[0213] Each chafing strip 22 is located near the bead 12. In this embodiment, it is desirable that the chafing strip 22 is made of cloth and rubber impregnated in the cloth. This chafing strip 22 may be integrated with the clinch 10.

[0214] In this tire 2, the tread 4 has main grooves 42 as grooves 26. As shown in FIG. 1, a plurality of, specifically, three main grooves 42 are engraved in this tread 4. These main grooves 42 are arranged at intervals in the axial direction. By engraving three main grooves 42 in this tread 4, four ribs 44 extending in the circumferential direction are formed. That is, the main groove 42 is between the ribs 44.

[0215] Each main groove 42 extends in the circumferential direction. The main groove 42 is continuous without interruption in the circumferential direction. The main groove 42 promotes the drainage of water existing between the road surface and the tire 2, for example, in rainy weather. Therefore, even when the road surface is wet, the tire 2 can sufficiently contact the road surface. D in FIG. 2 indicates the groove depth of the circumferential main groove 42 formed in the tread 4.

[0216] In the tire 2, regarding the content Sc (parts by mass) of the silane coupling agent with respect to 100 parts by mass of the rubber component in the cap layer 30, the thickness Tc (mm) of the cap layer 30, and the groove depth D (mm) of the main groove 42, it is desirable that Sc / Tc and Sc / D are within the aforementioned ranges.

Example

[0217] Hereinafter, examples (examples) considered preferable in implementation will be shown, but the scope of the present disclosure is not limited to the examples.

[0218] Hereinafter, various chemicals used in the manufacture of the tire will be collectively described. The chemicals are purified according to a conventional method as necessary. SBR: HPR850 manufactured by JSR Corporation (styrene content: 27.5% by mass, vinyl bond amount: 59.0% by mass) BR: BR730 manufactured by JSR Corporation (cis content: 95% by mass) Carbon black: Show Black N220 manufactured by Cabot Japan Limited (N 2 SA114m 2 / g) Silica 1: Ultrasil VN3 manufactured by Evonik Degussa GmbH (average particle size: 19 nm, N 2 SA: 175m 2 / g) Silica 2: K160 manufactured by Wilmar Corporation (average particle size: 15 nm, rice husk silica, N 2 SA: 154m 2 / g, CTAB: 152m 2 / g) Silane coupling agent 1: Si266 manufactured by Evonik Degussa GmbH (bis(3-triethoxysilylpropyl) disulfide, carbon number E: 10) Silane coupling agent 2: NXT manufactured by Momentive Performance Materials Inc. (3-octanoylthio-1-propyltriethoxysilane, carbon number E: 13) Dispersant: Liponol HT / 14 manufactured by Lion Specialty Chemicals Co., Ltd. (compound represented by the above formula (I-1)) Stearic acid: Tsubaki manufactured by NOF Corporation Zinc oxide: Zinc white No. 2 manufactured by Mitsui Mining & Smelting Co., Ltd. Wax: Sunoc N manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. Antioxidant 1: No Crack 6C manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. (N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine) Antioxidant 2: Antage RD manufactured by Kawaguchi Chemical Industry Co., Ltd. (polymer of 2,2,4-trimethyl-1,2-dihydroquinoline) Oil: Diana Process AH-24 manufactured by Idemitsu Kosan Co., Ltd. Sulfur: Powder sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. Vulcanization accelerator 1: Nocceler NS manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. (N-tert-butyl-2-benzothiazolylsulfenamide) Vulcanization accelerator 2: Nocceler D manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. (1,3-diphenylguanidine)

[0219] <Preparation of Test Tires> According to the compounding content shown in Table 1, using a 1.7L Banbury mixer manufactured by Kobe Steel, Ltd., materials other than sulfur and vulcanization accelerators are kneaded at 150°C for 5 minutes to obtain a kneaded product. Sulfur and vulcanization accelerators are added to the kneaded product, and it is kneaded using an open roll at 80°C for 5 minutes to obtain an unvulcanized rubber composition. The unvulcanized rubber composition for the cap tread is formed into the shape of a cap tread, and on a tire molding machine, it is laminated together with other tire members to form an unvulcanized tire, which is vulcanized at 170°C for 10 minutes to manufacture a test tire (size 205 / 70R15, passenger car tire).

[0220] Assuming test tires obtained from compositions with formulations and specifications changed according to Table 1, the results calculated based on the following evaluation methods are shown in each table. Note that the reference comparative example is as follows. Table 1: Comparative Example 1

[0221] <60°C tanδ Measurement> Samples with a size of 4 mm in width, 20 mm in length, and 1 mm in thickness are taken from the tread of the test tire (the circumferential direction of the tire is aligned with the longitudinal direction of the sample). Using an Iplexer manufactured by GABO, the loss tangent tanδ is measured under the conditions of a temperature of 60°C, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10 Hz, and an elongation mode, and it is expressed as an index with the reference comparative example set to 100. The larger the index, the lower the heat generation and the better the low fuel consumption performance.

[0222] <Low Fuel Consumption Performance> Using a rolling resistance tester, the rolling resistance when each test tire is running at a speed of 80 km / h is measured, and it is expressed as an index with the reference comparative example set to 100. The larger the index, the smaller the rolling resistance and the better the low fuel consumption performance.

[0223]

Table 1

[0224] The present invention (1) includes a rubber component, silica containing biomass-derived silica, and a silane coupling agent, wherein the content C of the silica relative to 100 parts by mass of the rubber component is 50 parts by mass or more, the average particle diameter A of the silica is 15 nm or less, and the rubber composition satisfies the following formula (1) for the content C of the silica, the average particle diameter A of the silica, and the average carbon number E of the silane coupling agent. (1) E×A / C>2.5

[0225] The present invention (2) is the rubber composition according to the present invention (1), which satisfies E×A / C>3.0.

[0226] The present invention (3) is the rubber composition according to the present invention (1) or (2), wherein E×A / C is 5.0 or less.

[0227] The present invention (4) is such that the rubber component includes butadiene rubber and styrene-butadiene rubber, and the rubber composition is an arbitrary combination of any one of the present inventions (1) to (3), wherein the content of the butadiene rubber in 100% by mass of the rubber component is 15 to 40% by mass, and the content of the styrene-butadiene rubber is 60 to 85% by mass.

[0228] The present invention (5) is the rubber composition according to any one of the present inventions (1) to (4), wherein the silane coupling agent includes a mercapto-based silane coupling agent.

[0229] The present invention (6) is the rubber composition according to any one of the present inventions (1) to (5), wherein the content of the plasticizer relative to 100 parts by mass of the rubber component is 10 parts by mass or less.

[0230] The present invention (7) is a tire having a cap tread composed of the rubber composition according to any one of the present inventions (1) to (6).

[0231] The present invention (8) is a tire according to the present invention (7), wherein the ratio (Sc / Tc) of the content Sc (parts by mass) of the silane coupling agent to 100 parts by mass of the rubber component in the cap tread and the thickness Tc (mm) of the cap tread is 0.8 or more.

[0232] The present invention (9) is a tire according to the present invention (7) or (8), wherein the ratio (Sc / D) of the content Sc (parts by mass) of the silane coupling agent to 100 parts by mass of the rubber component in the cap tread and the groove depth D (mm) of the circumferential groove formed in the tread is 0.9 or more.

Explanation of Signs

[0233] 2 Tire 4 Tread 6 Sidewall 8 Wing 10 Clincher 12 Bead 14 Carcass 16 Belt layer 18 Band 20 Inner liner 22 Chafer 24 Tread surface 26 Groove 28 Base layer 30 Cap layer 32 Bead core 34 Apex 36 Carcass ply 36a Main part 36b Turned-back part 38 Inner layer 40 Outer layer 42 Main groove 44 Rib CL Equatorial plane of the tire Tc Thickness of the cap tread D Main groove depth of the circumferential main groove formed in the tread

Claims

1. A rubber composition comprising a rubber component, silica containing biomass-derived silica, and a silane coupling agent, wherein the content C of the silica relative to 100 parts by mass of the rubber component is 50 parts by mass or more, the average particle size A of the silica is 15 nm or less, and the content C of the silica, the average particle size A of the silica, and the average carbon number E of the silane coupling agent satisfy the following formula (1). (1) E×A / C > 2.5

2. The rubber composition according to claim 1, satisfying E×A / C > 3.

0.

3. The rubber composition according to claim 1, wherein E×A / C is 5.0 or less.

4. wherein the rubber component includes butadiene rubber and styrene-butadiene rubber, and the content of the butadiene rubber in 100% by mass of the rubber component is 15% by mass or more and 40% by mass or less, and the content of the styrene-butadiene rubber is 60% by mass or more and 85% by mass or less. The rubber composition according to claim 1.

5. The rubber composition according to claim 1, wherein the silane coupling agent includes a mercapto-based silane coupling agent.

6. The rubber composition according to claim 1, wherein the content of the plasticizer relative to 100 parts by mass of the rubber component is 10 parts by mass or less.

7. A tire having a cap tread composed of the rubber composition according to claim 1.

8. The tire according to claim 7, wherein the ratio (Sc / Tc) of the content Sc (parts by mass) of the silane coupling agent to 100 parts by mass of the rubber component in the cap tread and the thickness Tc (mm) of the cap tread is 0.8 or more.

9. The tire according to claim 7, wherein the ratio (Sc / D) of the content Sc (parts by mass) of the silane coupling agent to 100 parts by mass of the rubber component in the cap tread and the groove depth D (mm) of the circumferential groove formed in the tread is 0.9 or more.

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