Side component rubber composition and tire

Abstract

To provide a side component rubber composition and a tire that achieve sustainability and exhibit high abrasion resistance upon a collision with a curb.SOLUTION: A side component rubber composition contains: a rubber component including an isoprene-based rubber and butadiene rubber and / or styrene-butadiene rubber; carbon black including recycled carbon black; and a hydrazide compound. The ratio (Cc / Ic) of the content Cc (pts.mass) of the carbon black per 100 pts.mass of the rubber component to the content Ic (mass%) of the isoprene-based rubber in 100 mass% of the rubber component is higher than 0.8.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] Side members such as sidewalls are greatly bent when the tire runs, and cracks and the like may cause problems (such as Patent Document 1). As causes, the generation of scratches due to insufficient fracture strength and the propagation rate of cracks are considered, both of which are contrary to the reduction of fuel consumption of rubber.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to solve the above problems, realize sustainability, and provide a rubber composition for side members and a tire having good abrasion resistance when colliding with a curb.

Means for Solving the Problems

[0005] The present invention includes a rubber component containing an isoprene rubber and a butadiene rubber and / or a styrene-butadiene rubber, a carbon black containing recycled carbon black, and a hydrazide compound, and relates to a rubber composition for side members in which the ratio (Cc / Ic) of the content Cc (parts by mass) of the carbon black to 100 parts by mass of the rubber component and the content Ic (mass%) of the isoprene rubber in 100 mass% of the rubber component exceeds 0.8.

Effects of the Invention

[0006] The present invention includes a rubber component containing an isoprene rubber and a butadiene rubber and / or a styrene-butadiene rubber, a carbon black containing recycled carbon black, and a hydrazide compound. The ratio (Cc / Ic) of the content Cc (parts by mass) of the carbon black to 100 parts by mass of the rubber component and the content Ic (mass%) of the isoprene rubber in 100 mass% of the rubber component exceeds 0.8. Since it is a rubber composition for side members, while realizing sustainability, the abrasion resistance when colliding with a curb can be improved.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0008] The rubber composition for side members includes a rubber component containing an isoprene rubber and a butadiene rubber and / or a styrene-butadiene rubber, a carbon black containing recycled carbon black, and a hydrazide compound. The ratio (Cc / Ic) of the content Cc (parts by mass) of the carbon black to 100 parts by mass of the rubber component and the content Ic (mass%) of the isoprene rubber in 100 mass% of the rubber component exceeds 0.8.

[0009] The mechanism by which the above-mentioned effects are obtained with the rubber composition for side members is not necessarily clear, but it is presumed as follows. The application of recycled carbon black and the like is progressing towards sustainability, but there is a concern that the surface functional groups will decrease and the strength will decrease when applying recycled carbon black. Therefore, by further applying a hydrazide compound, it is possible to suppress the decrease in strength and apply recycled carbon black to achieve sustainability. Therefore, it is presumed that the rubber composition for the side member realizes sustainability and improves the abrasion resistance when colliding with the curbstone.

[0010] The rubber composition for the side member contains a rubber component including an isoprene-based rubber and at least one selected from the group consisting of butadiene rubber and styrene-butadiene rubber. The isoprene-based rubber, butadiene rubber, and styrene-butadiene rubber may be used alone or in combination of two or more. Among them, from the viewpoint of obtaining more effects, it is desirable to include an isoprene-based rubber, butadiene rubber, and styrene-butadiene rubber.

[0011] The mechanism by which more effects can be obtained by including both butadiene rubber and styrene-butadiene rubber is not clear, but by using both, the occurrence rate of cracks and the like is reduced, and thereby, it is considered that while realizing sustainability, the abrasion resistance when colliding with the curbstone is improved.

[0012] In this specification, 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 rubber component is in a solid state at normal temperature (25°C).

[0013] 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 it is within the above range, the effect tends to be obtained better.

[0014] In this specification, the weight average molecular weight (Mw) and the number average molecular weight (Mn) can be determined by standard polystyrene conversion based on the measured values by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation).

[0015] The above rubber component 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 (a 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.

[0016] Examples of the above 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 a substituent. 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.

[0017] Examples of isoprene rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, modified IR, etc. As NR, for example, SIR20, RSS#3, TSR20, etc., which are common in the rubber industry, can be used. As IR, there is no particular limitation, and for example, IR2200, etc., which are common in the rubber industry, can be used. Examples of modified NR include deproteinized natural rubber (DPNR), high-purity natural rubber, etc. Examples of modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. Examples of modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, etc. These may be used alone or in combination of two or more.

[0018] BR is not particularly limited, and 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 contains 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 spectrometry.

[0019] The cis amount of BR means the cis amount of the BR when there is one type of BR, and the average cis amount when there are multiple types. 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, when, in 100% by mass of the rubber component, 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] For BR, either non-modified BR or modified BR can be used. Examples of modified BR include modified BR into which the same functional groups as those of modified rubbers are introduced. Also, BR can use hydrogenated butadiene polymer (hydrogenated BR).

[0021] As the BR, for example, products of Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd. and the like can be used.

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

[0023] The styrene content of the SBR is preferably 5% by mass or more, more preferably 20% by mass or more, still more preferably 24% by mass or more. The styrene content is preferably 60% by mass or less, more preferably 40% by mass or less, still more preferably 35% by mass or less. When it is within the above range, the effect tends to be obtained better. In addition, in this specification, the styrene content can be measured by 1 1H-NMR measurement.

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

[0025] The vinyl content of the SBR is preferably 3% by mass or more, more preferably 10% by mass or more, still more preferably 17% by mass or more. The vinyl content is preferably 50% by mass or less, more preferably 40% by mass or less, still more preferably 30% by mass or less. When it is within the above range, the effect tends to be obtained better. In addition, in this specification, the vinyl content (1,2-bonded butadiene unit content) can be measured by infrared absorption spectroscopy.

[0026] The vinyl content (amount of 1,2-bonded butadiene units) of SBR is the ratio of vinyl bonds when the total mass of the butadiene part in SBR is taken as 100 (unit: mass %), and vinyl content [mass %] + cis content [mass %] + trans content [mass %] = 100 [mass %]. When there is one type of SBR, it means the vinyl content of that SBR, and when there are multiple types, it means the average vinyl content. The average vinyl content of SBR can be calculated by Σ{content of each SBR × (100 [mass %] - styrene content of each SBR [mass %]) × vinyl content of each SBR [mass %]} / Σ{content of each SBR × (100 [mass %] - styrene content 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 content of 40 mass % and a vinyl content of 30 mass %, 15 parts by mass of SBR with a styrene content of 25 mass % and a vinyl content of 20 mass %, and the remaining 10 parts by mass are other than SBR, the average vinyl content 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 modified SBR include those with functional groups similar to modified rubbers introduced. Also, as SBR, hydrogenated styrene-butadiene copolymer (hydrogenated SBR) can be used.

[0028] As SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., etc. can be used. Also, those synthesized by known methods can be used.

[0029] The raw materials (monomers) of synthetic rubbers such as IR, SBR, and BR may be derived from underground resources such as petroleum and natural gas, 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 polyisoprene, 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 polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and / or recycled styrene (recycled styrene) as raw materials.

[0030] The method for producing recycled monomers is not particularly limited. For example, it may be synthesized from recycled naphtha obtained by decomposing rubber products such as tires. The method for producing recycled naphtha is not particularly limited. 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 IR, SBR, and BR may be derived from biomass. In this specification, biomass refers to substances derived from natural resources such as plants. The biomass is not particularly limited, and examples include agricultural and forestry products, sugar, wood chips, plant residues after obtaining useful components, ethanol derived from plants, biomass naphtha, and the like.

[0032] The biomass-derived monomers (biomass monomers) are not particularly limited, and examples thereof include biomass-derived butadiene and biomass-derived aromatic vinyls. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl is not particularly limited, and examples thereof include styrene. Further, the method for producing the biomass monomer is not particularly limited, and examples thereof include those by biological and / or chemical and / or physical conversion of animals and plants. Fermentation by microorganisms is typical as the biological conversion, and examples of the chemical and / or physical conversion include those by a catalyst, high heat, high pressure, electromagnetic waves, a critical liquid, and combinations thereof.

[0033] The polymers synthesized from the biomass monomer components (biomass polymers) are not particularly limited, and examples thereof include polybutadiene rubber synthesized from biomass-derived butadiene and aromatic vinyl / butadiene copolymers synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyls. Examples of the aromatic vinyl / butadiene copolymer include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0034] 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.

[0035] 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 is a value used as an index indicating the biomass ratio of a compound. The significance of this value is described below.

[0036] In one mole (6.02×10 23 pieces) of carbon atoms, there are about 6.02×10 11 pieces, which is about one trillionth of ordinary carbon atoms, of 14C exists. 14 C is called a radioactive isotope, and its half-life is 5730 years, decreasing regularly. It takes 226,000 years for all of them to decay. Therefore, after carbon dioxide in the atmosphere is taken up and fixed by plants, etc., in fossil fuels such as coal, oil, and natural gas, which are thought to have passed more than 226,000 years since fixation, 14 all of the C elements have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas 14 contain no C elements at all. Therefore, chemical substances produced using these fossil fuels as raw materials 14 also contain no C elements at all.

[0037] On the other hand, 14 C is constantly generated by nuclear reactions of cosmic rays in the atmosphere, and is balanced with the decrease due to radioactive decay. In the earth's atmospheric environment, 14 the amount of C is constant. Therefore, in the current environment, for substances derived from biomass resources that are cycling 14 the C concentration is about 1×10 -12 mol% with respect to the entire C atoms as described above. Therefore, by utilizing the difference between these values, the biomass ratio of a certain compound can be calculated.

[0038] This 14 C is generally measured as follows. Using accelerator mass spectrometry based on a tandem accelerator, 13 the C concentration ( 13 C / 12 C), 14 the C concentration ( 14 C / 12 C) is measured. In the measurement, 14 as a modern standard reference for the concentration of C, the 14The C concentration is adopted. As a specific reference material, the oxalic acid standard provided by NIST (National Institute of Standards and Technology) is used. The specific activity of carbon in this oxalic acid (radioactivity intensity of 14 C per 1 g of carbon) is separated for each carbon isotope, 13 For 14 C, it is corrected to a constant value, and the value after applying the decay correction from 1950 AD to the measurement date is used as the standard

[0039] C concentration value (100%). The ratio of this value to the value of the actually measured sample is the pMC value. 14 Therefore, if the rubber is made of 100% biomass-derived substances, although there are regional differences, etc., currently in the normal state, it often does not reach 100, so it will show a value of about 110 pMC. On the other hand, for chemical substances derived from fossil fuels such as petroleum, when the

[0040] C concentration is measured, it will show a value of about 0 pMC (for example, 0.3 pMC). This value corresponds to a biomass ratio of 0% mentioned above.

[0041] 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.

[0042] When the rubber composition for the side member contains BR, the content of BR in 100% by mass of the rubber component is preferably 20% by mass or more, more preferably 30% by mass or more, still more preferably 40% by mass or more, and is preferably 80% by mass or less, more preferably 60% by mass or less, still more preferably 50% by mass or less. When it is within the above range, the effect tends to be obtained more favorably.

[0043] When the rubber composition for the side member contains SBR, the content of SBR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, even more preferably 40% by mass or more, and is preferably 80% by mass or less, more preferably 60% by mass or less, still more preferably 50% by mass or less. When it is within the above range, the effect tends to be obtained more favorably.

[0044] Examples of rubber components other than isoprene rubber, BR, and SBR include styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), etc. Also, butyl rubber, fluororubber, etc. are included. These may be used alone or in combination of two or more.

[0045] The above rubber component may be subjected to a modification treatment or a hydrogenation treatment, and an extended rubber stretched by an oil, a resin, a liquid rubber component, etc. may be used.

[0046] The rubber composition for the side member contains carbon black containing recycled carbon black as a filler.

[0047] Examples of the recycled carbon black include recycled carbon black generated through thermal decomposition of waste tires. The thermal decomposition of waste tires can be carried out by a known method, for example, a thermal decomposition method at a temperature of 650°C or higher.

[0048] The nitrogen adsorption specific surface area (N2SA) of the recycled carbon black is preferably 30 m 2 / g or more, more preferably 50 m 2 / g or more, and even more preferably 65 m 2 / g or more. Also, the above N2SA is preferably 150 m 2 / g or less, more preferably 120 m 2 / g or less, even more preferably 100 m 2 / g or less, and particularly preferably 95 m 2 / g or less. When within the above range, the effect tends to be obtained more favorably. In addition, in this specification, the nitrogen adsorption specific surface area of carbon black is determined according to JIS K6217-2:2001.

[0049] Commercially available products can be used as the recycled carbon black. For example, products such as PB365 manufactured by Enrestec can be mentioned. PB365 is recycled carbon black generated through the thermal decomposition of waste tires, and its N2SA is 76 m 2 / g. Also, PB365 contains about 17% by mass of ash content.

[0050] In the rubber composition for the side member, the content of the recycled carbon black is preferably 5 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 50 parts by mass or more with respect to 100 parts by mass of the rubber component. Also, it is preferably 150 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 90 parts by mass or less. When within the above range, the effect tends to be obtained more favorably.

[0051] The rubber composition for the side member may contain ordinary carbon black other than the recycled carbon black. Such carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. The raw material of the carbon black may be a biomass material such as lignin or vegetable oil. Also, the method for producing the carbon black may be by combustion such as the furnace method, by hydrothermal carbonization (HTC), or by thermal decomposition of methane such as the thermal black method. As commercially available products, products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., Columbia Carbon Company, etc. can be used. These may be used alone or in combination of two or more.

[0052] The nitrogen adsorption specific surface area (N2SA) of the above carbon black is preferably 30 m 2 / g or more, more preferably 50 m 2 / g or more, still more preferably 70 m 2 / g or more. Also, the above N2SA is preferably 200 m 2 / g or less, more preferably 150 m 2 / g or less, still more preferably 130 m 2 / g or less, particularly preferably 120 m 2 / g or less. When within the above range, the effect tends to be obtained more favorably. In this specification, the nitrogen adsorption specific surface area of carbon black is determined according to JIS K6217-2:2001.

[0053] In the above rubber composition for side members, the content of carbon black (total amount of recycled carbon black and other carbon black) is preferably 5 parts by mass or more, more preferably 30 parts by mass or more, still more preferably 50 parts by mass or more, based on 100 parts by mass of the rubber component, and is also preferably 150 parts by mass or less, more preferably 100 parts by mass or less, still more preferably 90 parts by mass or less. When within the above range, the effect tends to be obtained more favorably.

[0054] The rubber composition for the side member may contain the recycled carbon black and fillers other than ordinary carbon black. Such fillers are not particularly limited, and materials known in the rubber field can be used. For example, inorganic fillers such as silica, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, mica, biochar (BIO CHAR); poorly dispersible fillers, etc. may be mentioned. Among them, silica is preferable from the viewpoint of obtaining more effects.

[0055] Although the mechanism by which more effects can be obtained by including silica is not clear, using silica as a filler may cause concern about a decrease in strength, but using a hydrazide compound can suppress the decrease in strength, thereby realizing sustainability and improving the abrasion resistance when colliding with the curb.

[0056] In the rubber composition for the side member, the silica that can be used is not particularly limited. For example, silica prepared by the dry method (anhydrous silica), silica prepared by the wet method (hydrous silica), etc., which are common in the tire industry, can be used. The raw material of silica is not particularly limited. For example, it may be a raw material derived from a mineral such as quartz, or a raw material derived from a living organism such as rice husk (for example, silica using a biomass material such as rice husk as a raw material), or silica recycled from a product containing silica may also be used. Among them, hydrous silica prepared by the wet method is preferable because it has many silanol groups. These silicas may be used alone or in combination of two or more.

[0057] Silica using a biomass material as a raw material can be obtained, for example, by extracting a silicate from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and reacting the silicate with sulfuric acid in the same manner as conventional wet silica to precipitate silicon dioxide, followed by filtration, washing with water, drying, and pulverization.

[0058] Silica recycled from products containing silica can be, for example, silica recovered from products containing silica such as electronic components such as semiconductors, tires, desiccants, and filter materials such as diatomaceous earth. The method of recovery is not particularly limited, and examples include thermal decomposition and decomposition by electromagnetic waves. Among them, silica recovered from electronic components such as semiconductors or tires is preferable.

[0059] When silica crystallizes, it does not dissolve in water and the silicic acid that is its component cannot be utilized. By controlling the combustion temperature and combustion time, crystallization of silica in rice husk ash can be suppressed (see, for example, Japanese Patent Application Laid-Open No. 2009-2594, Akita Prefectural University Web Journal B / 2019, vol. 6, p. 216-222, etc.).

[0060] Amorphous silica extracted from rice husks can be those commercially available from companies such as Wilmar.

[0061] When the rubber composition for the side member contains silica, the content of silica is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and preferably 150 parts by mass or less, more preferably 120 parts by mass or less, and still more preferably 100 parts by mass or less with respect to 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0062] The nitrogen adsorption specific surface area (N2SA) of silica is preferably 50 m 2 / g or more, more preferably 70 m 2 / g or more, still more preferably 80 m 2 / g or more. Also, the upper limit of the N2SA of silica is not particularly limited, but is preferably 350 m 2 / g or less, more preferably 300 m 2 / g or less, still more preferably 250 m 2 / g or less. When within the above range, the effect tends to be obtained more favorably. In this specification, the N2SA of silica is a value measured by the BET method in accordance with ASTM D3037-93.

[0063] Examples of the poorly dispersible filler include, for example, microfibrillated plant fibers, short fibrous cellulose, gel-like compounds, etc. Among them, microfibrillated plant fibers are preferred.

[0064] As the above microfibrillated plant fiber, cellulose microfibrils are preferred from the viewpoint 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.

[0065] 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.

[0066] When the rubber composition for the side member 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, and particularly preferably 10 parts by mass or more with respect to 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.

[0067] In the rubber composition for the side member, the content of the filler (total amount of recycled carbon black, normal carbon black, silica, etc.) is preferably 5 parts by mass or more, more preferably 30 parts by mass or more, still more preferably 50 parts by mass or more, and preferably 150 parts by mass or less, more preferably 100 parts by mass or less, still more preferably 90 parts by mass or less, based on 100 parts by mass of the rubber component. When it is within the above range, the effect tends to be obtained more favorably.

[0068] When the rubber composition for the side member contains silica, it is preferable to further contain a silane coupling agent. The silane coupling agent is not particularly limited, and those known in the rubber field can be used. For example, 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, etc. sulfide-based, 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, mercapto-based such as NXT and NXT-Z manufactured by Momentive, vinyl-based such as vinyltriethoxysilane and vinyltrimethoxysilane, amino-based such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane, glycidoxy-based such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane, nitro-based such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane, chloro-based such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane, etc. can be mentioned. As commercially available products, 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. These may be used alone or in combination of two or more kinds.

[0069] In the above rubber composition for side members, the content of the silane coupling agent is preferably 0.1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more with respect to 100 parts by mass of silica. The upper limit of the content is preferably 50 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less. When it is within the above range, the effect tends to be obtained more favorably.

[0070] The above rubber composition for side members contains a hydrazide compound. In this specification, the hydrazide compound refers to a compound having one or more groups represented by -C(=O)-NH-. The hydrazide compound may be used alone or in combination of two or more.

[0071] Among the above hydrazide compounds, from the viewpoint of obtaining more effects, the compound represented by the following formula (1) is desirable.

Chemical formula

[0072] In the above formula (1), the monovalent hydrocarbon groups of R 11 and R 12 may be linear, branched, or cyclic, and may have a substituent. The number of carbon atoms of the monovalent hydrocarbon group, excluding the number of carbon atoms of the substituent, is preferably 1 or more, and is preferably 10 or less, more preferably 8 or less, and still more preferably 4 or less. Examples of the monovalent hydrocarbon group include an alkyl group and an alkenyl group.

[0073] In the above formula (1), R 11 and R 12Specific examples of the monovalent hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, an isoamyl group, a 2-ethylbutyl group, an n-hexyl group, a cyclohexyl group, an n-heptyl group, a cyclohexylmethyl group, a cyclohexylethyl group, an n-octyl group, a 2-ethylhexyl group, a 3-n-propylheptyl group, an adamantyl group, an n-decyl group, a 3,7-dimethyloctyl group, and a 2-ethyloctyl group. Among them, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group are preferable, and a methyl group, an ethyl group, an n-propyl group, and an isobutyl group are more preferable.

[0074] In the above formula (1), R 13 Examples of the halogen group include -F and -Br.

[0075] Among the compounds represented by the above formula (1), from the viewpoint of obtaining more effects, the compound represented by the following formula (1-1) is preferable.

Chemical formula

[0076] The mechanism by which more effects can be obtained by using the compound represented by the formula (1-1) is not clear, but since the compound can suitably suppress the decrease in strength due to regenerated carbon black, it is considered that while realizing sustainability, the wear resistance when colliding with the curb is improved.

[0077] In the above formula (1-1), R 11 and R 12 Examples of the monovalent hydrocarbon group include the same groups as those of the above R 11 , R 12 .

[0078] In the rubber composition for the side member, the content of the hydrazide compound (total amount of the compound represented by formula (1) and other hydrazide compounds) 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, and preferably 10.0 parts by mass or less, more preferably 7.0 parts by mass or less, still more preferably 5.0 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.

[0079] In the rubber composition for the side member, the content of the compound represented by formula (1) 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, and preferably 10.0 parts by mass or less, more preferably 7.0 parts by mass or less, still more preferably 5.0 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.

[0080] In the rubber composition for the side member, the content of the compound represented by formula (1-1) 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, and preferably 10.0 parts by mass or less, more preferably 7.0 parts by mass or less, still more preferably 5.0 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.

[0081] The rubber composition for the side member may contain a plasticizer. In this specification, a plasticizer is a material that imparts plasticity to a rubber component, and is a concept that includes both plasticizers that are liquid at 25°C and plasticizers that are solid at 25°C. Examples of plasticizers include resin components, oils, liquid polymers, ester-based plasticizers, and the like. These plasticizers may be derived from mineral resources such as petroleum and natural gas, 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.

[0082] Specific examples of the above plasticizers include oils, liquid polymers, resins, and the like. These may be used alone or in combination of two or more.

[0083] Examples of oils include mineral oils, vegetable oils, animal oils, and the like. Also, from the perspective of life cycle assessment, waste oils after use in rubber mixers or engines, or refined waste cooking oils used in restaurants may be used.

[0084] In this specification, mineral oil refers to an oil derived from mineral resources such as petroleum and natural gas. Examples of mineral oils include paraffinic oils (mineral oils), naphthenic oils, aromatic oils, and the like. Specific examples of mineral 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), and the like. Also, oils with a low content of polycyclic aromatic (PCA) compounds can be used for environmental measures. Examples of the low-PCA-content oils include MES, TDAE, and heavy naphthenic oils.

[0085] In this specification, vegetable oils include, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice bran 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, as vegetable oils, there are also 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 the vegetable oil may be liquid or solid at 25°C. These vegetable oils may be used alone or in combination of two or more.

[0086] 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 the 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. Furthermore, the acylglycerol may be a monomer, a dimer, or a multimer of three or more units. Note that acylglycerols of two or more units can be obtained by thermal polymerization, oxidation polymerization, etc. Also, the acylglycerol may be liquid or solid at 25°C.

[0087] As a method for confirming whether the above acylglycerol is contained in the rubber composition, although not particularly limited, 1 it can be confirmed by 1H - NMR measurement. For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at 25°C for 24 hours. After removing the rubber composition, at room temperature 1When measuring 1H-NMR and setting the signal of tetramethylsilane (TMS) to 0.00 ppm, signals around 5.26 ppm, around 4.28 ppm, and around 4.15 ppm were 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.

[0088] The fatty acid is not particularly limited and may be an unsaturated fatty acid or a saturated fatty acid. Examples of unsaturated fatty acids include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. Examples of saturated fatty acids include butyric acid and lauric acid.

[0089] Among them, it is desirable that the fatty acid contains 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. In addition, in order to produce a vegetable oil containing such a fatty acid, plants may be improved by variety improvement, genetic recombination, genome editing, etc.

[0090] As the oil, for example, those commercially available from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Co., Ltd., Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kogyo Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0091] 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 a terminal or a main chain modified with a polar group. Further, hydrogenated products thereof can also be used.

[0092] 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 ~5.0×10 4 and more preferably 3.0×10 3 ~1.5×10 4 . Further, the lower limit or the upper limit of Mw of the liquid diene polymer may be 4500 or 8500. In the present specification, Mw of the liquid diene polymer is a polystyrene-reduced value measured by gel permeation chromatography (GPC).

[0093] Examples of the above liquid diene polymer include products of Sartomer Company and Kuraray Co., Ltd.

[0094] As the above resin, as a tire compound, a resin (resin) commonly used can be used, which 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. Further, 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.

[0095] 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 hydrogenated resins, it is desirable that the softening point is the same as above. Incidentally, 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.

[0096] The above aromatic vinyl polymer is a polymer containing an aromatic vinyl monomer as a structural 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.

[0097] The above-mentioned coumarone-indene resin is a resin containing coumarone and indene as the main monomer components constituting the resin skeleton (main chain). Examples of monomer components other than coumarone and indene contained in the skeleton include styrene, α-methylstyrene, methyl indene, vinyl toluene, and the like.

[0098] The above-mentioned coumarone resin is a resin containing coumarone as the main monomer component constituting the resin skeleton (main chain).

[0099] The above-mentioned indene resin is a resin containing indene as the main monomer component constituting the resin skeleton (main chain).

[0100] As the above-mentioned phenol resin, for example, known polymers such as those 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.

[0101] Examples of the above-mentioned rosin resin include rosin-based resins typified by natural rosin, polymerized rosin, modified rosin, ester compounds thereof, and hydrogenated products thereof.

[0102] Examples of the above-mentioned 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.

[0103] 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. As terpene compounds, α-pinene, β-pinene, etc. can be mentioned; as phenolic compounds, phenol, bisphenol A, etc. can be mentioned; and as aromatic compounds, styrene compounds (styrene, α-methylstyrene, etc.) can be mentioned. Among them, aromatic modified terpene resins are preferred.

[0104] 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 having a carboxyl group. Among them, solvent-free carboxyl group-containing styrene acrylic resins can be preferably used.

[0105] As the above resin, for example, 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 Catalyst Co., Ltd., ENEOS Co., Ltd., Arakawa Chemical Industries, Ltd., Tago Chemical Industries, Ltd., etc. can be used.

[0106] 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 plasticizer.

[0107] 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]

[0108] 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.

[0109] 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, 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.

[0110] 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.

[0111] Farnesene-based polymers with a weight average molecular weight (Mw) of 3,000 or more and 300,000 or less can be preferably used. The Mw of the farnesene-based polymer is preferably 8,000 or more, more preferably 10,000 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.

[0112] The farnesene-based polymer may be in a liquid state or a solid state at normal temperature (25°C). Among them, a liquid farnesene-based polymer in a liquid state at normal temperature (25°C) is desirable.

[0113] In the rubber composition for the side member, the content of the plasticizer (total amount of the plasticizer) 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 is preferably 60 parts by mass or less, more preferably 40 parts by mass or less, still more preferably 35 parts by mass or less. When 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 the resin-extended rubber.

[0114] In the rubber composition for the side member, the content of the solid plasticizer in a solid state at room temperature (25°C) 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 is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, still more preferably 10 parts by mass or less. When within the above range, the effect tends to be obtained more favorably.

[0115] In the rubber composition for the side member, the content of the resin in a solid state at room temperature (25°C) 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 is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, still more preferably 10 parts by mass or less. When within the above range, the effect tends to be obtained more favorably.

[0116] In the rubber composition for the side member, the content of the liquid plasticizer in a liquid state at room temperature (25°C) 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 is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, still more preferably 25 parts by mass or less. When 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.

[0117] In the rubber composition for the side member, the oil content 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 is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, still more preferably 25 parts by mass or less. When within the above range, the effect tends to be obtained more favorably. Note that the oil content includes the amount of oil contained in the oil-extended rubber.

[0118] The rubber composition for the side member may further contain vulcanized rubber particles. The vulcanized rubber particles are particles made of vulcanized rubber. Specifically, rubber powder etc. defined in JIS K 6316:2017 can be used. From the viewpoints of environmental consideration and cost, recycled rubber powder produced from crushed waste tires etc. is preferable. These may be used alone or in combination of two or more.

[0119] The vulcanized rubber particles are not particularly limited, and may be non-modified vulcanized rubber particles or modified vulcanized rubber particles.

[0120] As commercially available products of vulcanized rubber particles, for example, products of Lehigh, Murakami Rubber Industry Co., Ltd. etc. can be used.

[0121] In the rubber composition for the side member, the content of the vulcanized rubber particles is preferably 5 parts by mass or more, more preferably 7 parts by mass or more, still more preferably 10 parts by mass or more, based on 100 parts by mass of the rubber component, and is also preferably 30 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 15 parts by mass or less. When within the above range, the effect tends to be obtained more favorably.

[0122] From the viewpoints of crack resistance, ozone resistance etc., the rubber composition for the side member preferably contains an antioxidant.

[0123] 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), and 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, etc. 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., etc. can be used.

[0124] In the above rubber composition for side members, 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 3.4 parts by mass or more, based on 100 parts by mass of the rubber component. The content is preferably 10.0 parts by mass or less, more preferably 6.0 parts by mass or less.

[0125] The above rubber composition for side members preferably contains stearic acid. In the rubber composition for the side member, the content of stearic acid 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, 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.

[0126] 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.

[0127] The rubber composition for the tire preferably contains zinc oxide. In the rubber composition for the side member, the content of zinc oxide 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, and preferably 6.0 parts by mass or less, more preferably 4.0 parts by mass or less, based on 100 parts by mass of the rubber component.

[0128] As the zinc oxide, conventionally known ones can be used. For example, products of Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Sho-Doh Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used.

[0129] The rubber composition for the side member may be blended with wax. In the rubber composition for the side member, the content of wax is preferably 0.5 parts by mass or more, more preferably 1.6 parts by mass or more, and preferably 8.0 parts by mass or less, more preferably 5.0 parts by mass or less, based on 100 parts by mass of the rubber component.

[0130] The wax is not particularly limited, and any wax commonly used in the tire industry can be preferably used. For example, mineral waxes, plant-derived waxes, etc. can be mentioned. Mineral waxes refer to waxes derived from mineral resources such as oil and natural gas. Plant-derived waxes refer to waxes derived from natural resources such as plants. Among them, mineral waxes are preferred. Examples of plant-derived waxes include rice wax, carnauba wax, candelilla wax, etc. Examples of mineral waxes include paraffin wax, microcrystalline wax, these selected special waxes, etc., and paraffin wax is preferred. Note that the wax according to this embodiment does not contain stearic acid. As the wax, for example, those commercially available from Ouchi Shinsei Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramelt Co., etc. can be used. These waxes may be used alone or in combination of two or more.

[0131] In the rubber composition for the side member, it is preferable to compound sulfur as a crosslinking agent in terms of forming appropriate crosslinking chains in the polymer chain and imparting good performance.

[0132] In the above rubber composition for tires, the sulfur content is 1.0 part by mass or more, preferably 1.5 parts by mass or more, more preferably 2.0 parts by mass or more with respect to 100 parts by mass of the rubber component. The sulfur 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. When it is within the above range, the effect tends to be obtained more favorably.

[0133] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, soluble sulfur, etc., which are commonly used in the rubber industry. As commercial products, products of companies such as Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemicals Corporation, Flexsys, Nippon Karyu Industry Co., Ltd., Hosoi Chemical Industry Co., Ltd. can be used. These may be used alone or in combination of two or more.

[0134] The rubber composition for the side member preferably contains a vulcanization accelerator. In the rubber composition for the side member, 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 0.5 parts by mass or more, more preferably 0.8 parts by mass or more, and still more preferably 1.0 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 6.0 parts by mass or less, and still more preferably 5.0 parts by mass or less.

[0135] 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.

[0136] In addition to the above components, the rubber composition for the side member may be appropriately blended with compounding agents commonly used in the tire industry, such as materials such as mold release agents.

[0137] In the rubber composition for the side member, the ratio (Cc / Ic) of the content Cc (parts by mass) of the carbon black to 100 parts by mass of the rubber component and the content Ic (mass%) of the isoprene-based rubber in 100 mass% of the rubber component exceeds 0.80. Preferably, the Cc / Ic exceeds 0.85, more preferably exceeds 0.90, still more preferably exceeds 0.95, and preferably is less than 3.00, more preferably less than 2.50, still more preferably less than 2.00. When it is within the above range, the effect tends to be obtained more favorably.

[0138] In the rubber composition for the side member, it is desirable that the ratio (Cc / Hc) of the content Cc (parts by mass) of the carbon black to 100 parts by mass of the rubber component and the content Hc (parts by mass) of the hydrazide compound to 100 parts by mass of the rubber component is 12.5 or more and 100 or less. Preferably, the Cc / Hc is 17.5 or more, more preferably 22.5 or more, still more preferably 25.0 or more, and preferably 50.0 or less, more preferably 40.0 or less, still more preferably 35.0 or less. When it is within the above range, the effect tends to be obtained more favorably.

[0139] Although the mechanism by which more effects can be obtained by adjusting the Cc / Hc to be 12.5 or more and 100 or less is not clear, the concern about the strength reduction due to the recycled carbon black can be preferably suppressed by the hydrazide compound, so it is considered that the sustainability is realized and the abrasion resistance at the time of collision with the curb is improved.

[0140] In this specification, various materials containing carbon atoms (for example, rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from carbon dioxide in the atmosphere. As a method for obtaining the above-mentioned composition from carbon dioxide, carbon dioxide may be directly converted, or methane obtained through a methanation process for synthesizing methane from carbon dioxide may be converted.

[0141] The rubber composition for the side member is kneaded using a rubber kneading device such as an open roll or a Banbury mixer for each of the above components, and then a crosslinked rubber composition is obtained by a method such as crosslinking.

[0142] As the kneading conditions, in the base kneading step of kneading additives other than the vulcanizing agent and the vulcanization accelerator, the kneading temperature is usually 50 to 200°C, preferably 80 to 190°C, and the kneading time is usually 30 seconds to 30 minutes, preferably 1 minute to 30 minutes. In the finishing kneading step of kneading the vulcanizing agent and the vulcanization accelerator, the kneading temperature is usually 100°C or lower, preferably room temperature to 80°C. 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 usually 120 to 200°C, preferably 140 to 180°C.

[0143] The rubber composition for the side member is used for the side member of a tire. In this specification, the side member is a member that is disposed on the outer side in the tire axial direction of the tread portion and constitutes the outermost surface of the tire. Specifically, examples include the sidewall, the clinch, etc.

[0144] The sidewall is a member disposed on the outside of the case from the shoulder portion to the bead portion. Specifically, it is a member shown in FIG. 1 of JP-A-2005-280612, FIG. 1 of JP-A-2000-185529, etc.

[0145] The clinch is a rubber portion that covers the contact portion with the rim existing at the lower part of the sidewall, and is also referred to as a clinch apex or a rubber chafer. Specifically, for example, it is a member shown in FIG. 1 of JP-A-2008-75066.

[0146] Among others, from the viewpoint of obtaining more effects, it is desirable to apply the rubber composition for the side member to the sidewall.

[0147] The above tire is manufactured by a conventional method using the above rubber composition for side members. That is, a composition blended with various additives as required is extruded into the shape of various side members such as sidewalls at the uncrosslinked or unvulcanized stage, molded 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.

[0148] The above tire is not particularly limited, and examples include pneumatic tires, solid tires, airless tires, etc. Among them, pneumatic tires are preferred.

[0149] 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 stud tire), an all-season tire, a run-flat tire, an aircraft tire, a mining tire, etc.

[0150] In a tire having a side member composed of the above rubber composition for side members, the side member has a maximum thickness T (mm) in the side member. In this specification, the maximum thickness T of the side member means the maximum value of the thicknesses of the rubber layers constituting each side member. The thickness at each point on the outer surface of the tire of each side member is a value measured along the normal line of the outer surface of the tire of each side member at that point, and the maximum thickness T of each side member is the maximum value of the thicknesses at each point. When the side member is composed of two or more rubber layers, the maximum thickness T of the side member refers to the maximum value of the total thickness of the two or more rubber layers.

[0151] In the above tire, the maximum thickness T (mm) of the side member is preferably 2.0 mm or more, more preferably 2.5 mm or more, still more preferably 2.8 mm or more. The upper limit is preferably 20.0 mm or less, more preferably 15.0 mm or less, still more preferably 10.0 mm or less, and particularly preferably 5.0 mm or less. When within the above range, the effect tends to be obtained more favorably.

[0152] Although the mechanism by which more effects can be obtained by adjusting the maximum thickness T of the tire member within a predetermined range is not clear, it is considered that by setting the maximum thickness of the side member within a predetermined range, the rubber strength is ensured, and thereby, while realizing sustainability, the wear resistance during collision with a curb is improved.

[0153] When the side member is a sidewall, the sidewall has a predetermined maximum thickness Ts (mm). In this specification, the maximum thickness Ts of the sidewall means the maximum value of the thickness of the sidewall. The thickness at each point on the outer surface of the tire of the sidewall is a value measured along the normal line of the outer surface of the tire of the sidewall at that point, and the maximum thickness Ts of the sidewall is the maximum value of the thickness at each point.

[0154] In the above tire, the maximum thickness Ts (mm) of the sidewall is preferably 2.0 mm or more, more preferably 2.5 mm or more, still more preferably 2.8 mm or more. The upper limit is preferably 20.0 mm or less, more preferably 6.0 mm or less, still more preferably 5.0 mm or less, and particularly preferably 4.0 mm or less. When within the above range, the effect tends to be obtained more favorably.

[0155] In this specification, dimensions such as thickness are values measured in the normal state. The "normal state" refers to a state where the tire is mounted on a standard rim, filled with the standard internal pressure, and is unloaded. Here, the "standard rim" is the rim defined for each tire in the standard system including the standard on which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Association), it is the standard rim in the applicable size described in the "JATMA YEAR BOOK"; in the case of ETRTO (The European Tyre and Rim Technical Organisation), it is the "Measuring Rim" described in the "STANDARDS MANUAL"; in the case of TRA (The Tire and Rim Association, Inc.), it is the "Design Rim" described in the "YEAR BOOK". Refer to JATMA, ETRTO, and TRA in this order, and follow the standard if there is an applicable size during the reference. In the case of a tire not defined in the standard, it refers to the rim with the smallest rim diameter and then the narrowest rim width among the rims that can be mounted on the tire and can maintain the internal pressure, that is, the rim that does not cause air leakage between the rim and the tire. Also, the "standard internal pressure" refers to the air pressure defined for each tire in the standard system including the standard on which the tire is based. In the case of JATMA, it is the "maximum air pressure"; in the case of ETRTO, it is the "INFLATION PRESSURE"; in the case of TRA, it refers to the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". Refer to JATMA, ETRTO, and TRA in this order, and follow the standard if there is an applicable size during the reference. In the case of a tire not defined in the standard, it refers to the standard internal pressure (however, 250 KPa or more) of another tire size (defined in the standard) with the standard rim described as the standard rim. In the case where multiple standard internal pressures of 250 KPa or more are described, it refers to the minimum value among them.

[0156] In the above tire, the product (Hc × T) of the content Hc (parts by mass) of the hydrazide compound with respect to 100 parts by mass of the rubber component of the rubber composition for the side member constituting the side member and the maximum thickness T (mm) of the side member is preferably 1.0 or more and 200 or less. The above Hc × T is preferably 5.0 or more, more preferably 7.5 or more, and still more preferably 10.0 or more. The upper limit of Hc × T is not particularly limited, but is preferably 150 or less, more preferably 100 or less, still more preferably 70 or less, and particularly preferably 50 or less. When within the above range, the effect tends to be obtained more favorably.

[0157] The mechanism by which a more effective result can be obtained by adjusting to a predetermined Hc × T is not clear, but by setting the maximum thickness of the side member within a predetermined range, good rubber strength can be obtained, and the decrease in strength is suppressed by the hydrazide compound. Thus, it is considered that while realizing sustainability, the wear resistance when colliding with a curb is improved.

[0158] In the above tire, the product (Hc × Ts) of the content Hc (parts by mass) of the hydrazide compound with respect to 100 parts by mass of the rubber component of the rubber composition for the sidewall constituting the sidewall and the maximum thickness Ts (mm) of the sidewall is preferably 1.0 or more and 60 or less. The above Hc × Ts is preferably 5.0 or more, more preferably 7.5 or more, and still more preferably 10.0 or more. The upper limit of Hc × Ts is not particularly limited, but is preferably 50 or less, more preferably 40 or less, and still more preferably 30 or less. When within the above range, the effect tends to be obtained more favorably.

[0159] The tire having a side member composed of the above rubber composition for the side member has a predetermined tread groove depth. The tread groove depth is the distance in the tire meridian direction to the deepest part of the groove extending in an arbitrary direction defining various tread patterns formed on the tread surface of the vulcanized tire. In this specification, the groove depth D of the tread means the distance measured along the normal line of the plane obtained by extending the plane forming the ground contact surface of the outermost surface of the tread in the circumferential groove, from the plane obtained by extending the plane forming the ground contact surface to the deepest groove bottom, and refers to the maximum distance among the groove depths of the provided circumferential grooves.

[0160] In the above tire, the groove depth D (mm) of the circumferential groove formed in the tread is preferably 5.0 mm or more, more preferably 6.0 mm or more, still more preferably 8.0 mm or more, and is preferably 20.0 mm or less, more preferably 15.0 mm or less, still more preferably 10.0 mm or less. When within the above range, the effect tends to be obtained more favorably.

[0161] The mechanism by which a more favorable effect is obtained in the case of the groove depth D within a predetermined range is not clear, but it is considered that by adjusting the groove depth to within a predetermined range, the rubber strength is ensured, and thereby the durability performance is improved.

[0162] In a tire having a tread and a side member, the product (Hc × D) of the content Hc (parts by mass) of the hydrazide compound in the rubber composition for the side member constituting the side member with respect to 100 parts by mass of the rubber component and the groove depth D (mm) of the circumferential groove formed in the tread is preferably 2.5 or more and 200 or less. The above Hc × D is preferably 10 or more, more preferably 15 or more, still more preferably 20 or more. The upper limit of Hc × D is not particularly limited, but is preferably 150 or less, more preferably 120 or less, still more preferably 100 or less. When within the above range, the effect tends to be obtained more favorably.

[0163] The mechanism by which a more favorable effect is obtained by adjusting to a predetermined Hc × D is not clear, but it is considered that a better rubber strength is obtained due to the groove depth within a predetermined range, and the decrease in strength is suppressed by the hydrazide compound, and thereby the durability performance is improved.

[0164] Hereinafter, an example of a tire will be described with reference to the drawings, but the above tire is not limited to such a form.

[0165] In FIG. 1, the vertical direction is the radial direction of the tire 2, the left - right direction is the axial direction of the tire 2, and the direction perpendicular to the paper surface is the circumferential direction of the tire 2. The tire 2 is symmetric about the left - right. The tread 4 is a single - layer - structure tread.

[0166] Note that, in FIG. 1, an example of the single - layer - structure tread 4 is shown, but a two - layer - structure tread composed of a cap tread and a base tread, or a tread having a structure of three or more layers may also be used.

[0167] In the tire 2, each sidewall 6 extends substantially radially inward from the edge of the tread 4. The radially outer portion of this sidewall 6 is joined to the tread 4. The radially inner portion of this sidewall 6 is joined to the clinch 10. This sidewall 6 can prevent damage to the carcass 14.

[0168] In the tire 2 of FIG. 1, the sidewall 6 is composed of the above - mentioned rubber composition for side members. That is, the sidewall 6 contains a rubber component containing isoprene - based rubber and butadiene rubber and / or styrene - butadiene rubber, a carbon black containing recycled carbon black, and a hydrazide compound, and the ratio (Cc / Ic) of the content Cc of the carbon black to 100 parts by mass of the rubber component and the content Ic of the isoprene - based rubber in 100% by mass of the rubber component exceeds 0.8, and is composed of a rubber composition for sidewall.

[0169] In the tire 2 of FIG. 1, the maximum thickness Ts of the sidewall 6 is the maximum dimension among the thicknesses of each sidewall at each point on the surface of the sidewall 6, and in the example of FIG. 1, it is indicated by Ts.

[0170] 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.

[0171] Each clinch 10 is located substantially radially inward of the sidewall 6 and has at least one portion in contact with the rim.

[0172] The carcass 14 includes a carcass ply 36. In this tire 2, the carcass 14 consists of a single carcass ply 36, but it may be composed of two or more plies.

[0173] In this tire 2, the carcass ply 36 is stretched between the bead cores 32 on both sides and extends along the tread 4 and the sidewall 6. The carcass ply 36 is folded back from the axial inner side toward the outer side around each bead core 32. By this folding, a main portion 36a and a pair of folded-back portions 36b are formed in the carcass ply 36. That is, the carcass ply 36 includes the main portion 36a and the pair of folded-back portions 36b.

[0174] Each bead core 32 includes a bead apex 34 extending radially outward from the 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.

[0175] Although not shown, the carcass ply 36 preferably consists of a 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 from 75° to 90°. In other words, this carcass 14 preferably has a radial structure.

[0176] 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 apparent from FIG. 1, it is desirable that in the axial direction, 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 0.6 times or more and preferably 0.9 times or less of the cross-sectional width of the tire 2.

[0177] Each of the inner layer 38 and the outer layer 40 preferably consists of a plurality of parallel single-wire steel cords (steel monofilaments) and topping rubber (coating rubber). In other words, the belt layer 16 contains a plurality of parallel steel monofilaments.

[0178] The band 18 in FIG. 1 is located radially outside the belt layer 16. In the axial direction, the band 18 has the same width as the width of the belt layer 16. This band 18 may have a width larger than the width of this belt layer 16.

[0179] Although not shown, the band 18 preferably consists of a cord and topping rubber. The cord is wound in a spiral. This band 18 has a so-called jointless structure. The cord extends substantially in the circumferential direction. The angle of the cord with respect to the circumferential direction is preferably 5° or less, and further preferably 2° or less. Since the belt layer 16 is constrained by this cord, lifting of the belt layer 16 is suppressed.

[0180] 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.

[0181] FIG. 2 is an enlarged view near the tread 4 of FIG. 1. The tire of FIG. 2 is the tire 2 having a groove 26 on the tire equatorial plane (on the CL).

[0182] 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.

[0183] Each chafer 22 is located near the bead 12. In this embodiment, it is desirable that the chafer 22 consists of cloth and rubber impregnated in the cloth. The chafer 22 may be integrated with the clinch 10.

[0184] In this tire 2, the tread 4 has main grooves 42 as grooves 26. As shown in FIG. 1, a plurality, 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.

[0185] 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. For this reason, even when the road surface is wet, the tire 2 can come into sufficient contact with the road surface.

[0186] D in FIG. 2 indicates the groove depth of the circumferential main groove 42 formed in the tread 4.

[0187] In the tire 2, the content Cc of carbon black with respect to 100 parts by mass of the rubber component of the sidewall rubber composition constituting the sidewall 6, the content Ic of isoprene rubber in 100% by mass of the rubber component, the content Hc of the hydrazide compound with respect to 100 parts by mass of the rubber component, and the maximum thickness Ts of the sidewall 6, and the groove depth D of the circumferential groove are desirably within the aforementioned ranges. Also, Cc / Hc, Hc×T, and Hc×D are desirably within the aforementioned ranges.

Example

[0188] Hereinafter, examples (embodiments) considered preferable in implementation are shown, but the scope of the present invention is not limited to the embodiments.

[0189] Hereinafter, various chemicals used in the production of tires will be collectively described. The chemicals are purified according to established methods as necessary. NR: TSR20 BR: BR150B manufactured by Ube Industries, Ltd. (cis content: 97% by mass) SBR: SBR1502 manufactured by Sumitomo Chemical Co., Ltd. (styrene content: 23.5% by mass) Carbon black: Diablack N550 manufactured by Mitsubishi Chemical Corporation (N2SA: 40 m 2 / g) Recycled carbon black: SS550 manufactured by Streble Green Carbon (recovered carbon black obtained from the thermal decomposition process of tires) Silica: Ultrasil VN3 (manufactured by Evonik, N2SA 175 m 2 / g) Silane coupling agent: Si266 manufactured by Evonik (bis(3-triethoxysilylpropyl) disulfide) Oil: Diana Process NH-70S manufactured by Idemitsu Kosan Co., Ltd. (aromatic process oil) Hydrazide compound: The compound represented by the above formula (1-1) (R 11 : methyl group, R 12 : isobutyl group) Wax: Oz Ace 0355 (manufactured by Nippon Seiro Co., Ltd.) Antioxidant 1: Nocrack 6C manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. (N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine) Antioxidant 2: Nocrack 224 manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. (poly(2,2,4-trimethyl-1,2-dihydroquinoline)) Stearic acid: manufactured by NOF Corporation Zinc oxide: Three types of zinc oxide (manufactured by Hakusuitech Co., Ltd.) Sulfur: Powder sulfur (manufactured by Tsurumi Chemical Industry Co., Ltd.) Vulcanization accelerator: Nocceler CZ-G (N-cyclohexyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

[0190] <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 accelerator are kneaded at 150 °C for 5 minutes to obtain a kneaded product. Sulfur and vulcanization accelerator are added to the kneaded product, and it is kneaded at 80 °C for 5 minutes using an open roll to obtain an unvulcanized rubber composition. The unvulcanized rubber composition is formed into the shape of a sidewall, and on a tire molding machine, it is bonded 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 / 55R16, passenger car tire).

[0191] 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 Table 1. Note that the reference comparative example is as follows. Table 1: Comparative Example 1

[0192] <Abrasion resistance when colliding with a curb> Samples are taken from the sidewall of the test tire, and a tensile test is carried out using a No. 3 dumbbell-shaped test piece in accordance with JIS K6251 "Vulcanized Rubber and Thermoplastic Rubber - Method for Determining Tensile Properties". The breaking strength (TB) and elongation at break (EB) are measured, and the fracture energy (TB × EB / 2) is calculated. Taking the fracture energy of the reference comparative example as 100, the fracture energy of each formulation is expressed as an index. The larger the value, the better the abrasion resistance when colliding with a curb.

[0193]

Table 1

[0194] The present invention (1) includes a rubber component containing an isoprene rubber and a butadiene rubber and / or a styrene-butadiene rubber, a carbon black containing a recycled carbon black, and a hydrazide compound. It is a rubber composition for a side member in which the ratio (Cc / Ic) of the content Cc (parts by mass) of the carbon black to 100 parts by mass of the rubber component and the content Ic (mass%) of the isoprene rubber in 100 mass% of the rubber component exceeds 0.8.

[0195] The present invention (2) is the rubber composition for a side member according to the present invention (1) containing silica.

[0196] The present invention (3) is the rubber composition for a side member according to the present invention (1) or (2) containing a butadiene rubber and a styrene-butadiene rubber.

[0197] The present invention (4) is a rubber composition for a side member which is any combination of the present inventions (1) to (3) in which the ratio (Cc / Hc) of the content Cc (parts by mass) of the carbon black to 100 parts by mass of the rubber component and the content Hc (parts by mass) of the hydrazide compound to 100 parts by mass of the rubber component is 12.5 or more and 100 or less.

[0198] The present invention (5) is a rubber composition for a side member which is any combination of the present inventions (1) to (4) in which the hydrazide compound contains a compound represented by the following formula (1-1).

[0199] The present invention (6) is a tire including a side member composed of a rubber composition for a side member which is any combination of the present inventions (1) to (5).

[0200] The present invention (7) is the tire according to the present invention (6) in which the maximum thickness T of the side member is 2.0 mm or more and 5.0 mm or less.

[0201] The present invention (8) is a tire according to the present invention (6) or (7), wherein the product (Hc×T) of the content Hc (parts by mass) of the hydrazide compound with respect to 100 parts by mass of the rubber component of the rubber composition for side members and the maximum thickness T (mm) of the side member is 5.0 or more and 50 or less.

[0202] The present invention (9) includes a tread, and is a tire in any combination of the present inventions (6) to (8), wherein the groove depth D of the circumferential groove formed in the tread is 8.0 mm or more and 15.0 mm or less.

[0203] The present invention (10) has a tread, and is a tire in any combination of the present inventions (6) to (9), wherein the product (Hc×D) of the content Hc (parts by mass) of the hydrazide compound with respect to 100 parts by mass of the rubber component of the rubber composition for side members and the groove depth D (mm) of the circumferential groove formed in the tread is 15 or more and 100 or less.

Explanation of reference numerals

[0204] 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 32 Bead core 34 Bead apex 36 Carcass ply 36a Main part 36b Turn-up part 38 Inner layer 40 Outer layer 42 Main groove 44 Rib CL Equatorial plane of the tire Maximum thickness of the Ts sidewall Main groove depth of the circumferential main groove formed in the D tread

Claims

1. A rubber composition comprising a rubber component containing an isoprene rubber and a butadiene rubber and / or a styrene-butadiene rubber, a carbon black containing recycled carbon black, and a hydrazide compound, wherein a ratio (Cc / Ic) of a content Cc (parts by mass) of the carbon black to 100 parts by mass of the rubber component and a content Ic (mass %) of the isoprene rubber in 100 mass % of the rubber component exceeds 0.8, the rubber composition for a side member.

2. The rubber composition for a side member according to claim 1, further comprising silica.

3. The rubber composition for a side member according to claim 1, further comprising a butadiene rubber and a styrene-butadiene rubber.

4. The rubber composition for a side member according to claim 1, wherein a ratio (Cc / Hc) of a content Cc (parts by mass) of the carbon black to 100 parts by mass of the rubber component and a content Hc (parts by mass) of the hydrazide compound to 100 parts by mass of the rubber component is 12.5 or more and 100 or less.

5. The rubber composition for a side member according to claim 1, wherein the hydrazide compound includes a compound represented by the following formula (1-1). 【Chemical 1】

6. A tire comprising a side member made of the rubber composition for a side member according to claim 1.

7. The tire according to claim 6, wherein a maximum thickness T of the side member is 2.0 mm or more and 5.0 mm or less.

8. The tire according to claim 6, wherein a product (Hc × T) of a content Hc (parts by mass) of the hydrazide compound per 100 parts by mass of the rubber component of the rubber composition for the side member and a maximum thickness T (mm) of the side member is 5.0 or more and 50 or less.

9. Comprising a tread, The tire according to claim 6, wherein a groove depth D of a circumferential groove formed in the tread is 8.0 mm or more and 15.0 mm or less.

10. Having a tread, The tire according to claim 6, wherein a product (Hc × D) of a content Hc (parts by mass) of the hydrazide compound per 100 parts by mass of the rubber component of the rubber composition for the side member and a groove depth D (mm) of a circumferential groove formed in the tread is 15 or more and 100 or less.

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