Tire

Abstract

To provide a tire that is excellent in integrated performance of steering stability, abrasion resistance and fuel efficiency.SOLUTION: A tire comprises a tire member composed of rubber compositions including rubber components and carbon black including regenerated carbon black. The rubber compositions include nitrogen compounds. Nitrogen amounts with respect to 100 parts by mass of the rubber components are above 0.20 parts by mass. Contents A (parts by mass) of the carbon black with respect to 100 parts by mass of the rubber components, the nitrogen amounts B (parts by mass) and a maximum thickness C (mm) of the tire member satisfy the following formula: (1) A×B / C>0.5.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] Recently, from the viewpoints such as environmental consideration, improvement in low fuel consumption, handling stability, wear resistance, etc. has been desired for tires.

Summary of the Invention

Problems to be Solved by the Invention

[0003] However, since low fuel consumption and handling stability and wear resistance are generally contradictory performances, it is difficult to improve them in a well-balanced manner.

[0004] An object of the present invention is to solve the above problems and provide a tire excellent in the overall performance of handling stability, wear resistance, and low fuel consumption.

Means for Solving the Problems

[0005] The present invention is a tire including a tire member composed of a rubber composition containing a rubber component and carbon black including recycled carbon black, wherein the rubber composition contains a nitrogen compound, the amount of nitrogen with respect to 100 parts by mass of the rubber component is 0.20 parts by mass or more, the content A (parts by mass) of the carbon black, the amount B (parts by mass) of the nitrogen, and the maximum thickness C (mm) of the tire member with respect to 100 parts by mass of the rubber component relate to a tire satisfying the following formula (1). (1) A×B / C > 0.5

Effects of the Invention

[0006] The present invention relates to a tire comprising a tire member composed of a rubber composition containing a rubber component and carbon black including recycled carbon black, wherein the rubber composition contains a nitrogen compound, the amount of nitrogen with respect to 100 parts by mass of the rubber component is 0.20 parts by mass or more, and the content A (parts by mass) of the carbon black, the amount of nitrogen B (parts by mass), and the maximum thickness C (mm) of the tire member with respect to 100 parts by mass of the rubber component satisfy the above formula (1). Therefore, a tire excellent in the overall performance of low fuel consumption and wear resistance can be provided.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0008] The above tire includes a tire member composed of a rubber composition containing a rubber component and carbon black including recycled carbon black, the rubber composition contains a nitrogen compound, the amount of nitrogen with respect to 100 parts by mass of the rubber component is 0.20 parts by mass or more, and the content A (parts by mass) of the carbon black, the amount of nitrogen B (parts by mass), and the maximum thickness C (mm) of the tire member with respect to 100 parts by mass of the rubber component satisfy the formula (1) "A × B / C > 0.5".

[0009] The mechanism (reason) by which the above-described effects are obtained by the above tire is not necessarily clear, but is presumed as follows. When recycled carbon black and a nitrogen compound are used, the total acid amount of recycled carbon black is larger than that of general-purpose carbon black, and the reactivity with basic substituents is high. Therefore, basic substituents (such as isocyanate) react more with the acidic groups of recycled carbon black, and substituents (such as aromatic rings) that interact with the polymer are modified on the surface of the recycled carbon black, improving the affinity with the polymer and greatly improving the reinforcing property. In addition, by improving the compatibility with the polymer, the dispersibility of carbon black is improved, and the low fuel consumption performance can be enhanced. Furthermore, by enhancing the reinforcing property, it becomes possible to reduce the thickness of the tire member, and the low fuel consumption performance can be further improved by weight reduction. Therefore, when the recycled carbon black and the nitrogen compound are contained in a predetermined composition, and the carbon black content A, the nitrogen amount B, and the maximum thickness C of the tire member satisfy the formula (1) "A × B / C > 0.5", based on the above mechanisms, it is presumed that the reinforcing property and the low fuel consumption property are improved in a well-balanced manner, and the overall performance of handling stability, wear resistance, and low fuel consumption performance is enhanced.

[0010] Thus, the above tire solves the problem (objective) of improving the overall performance of handling stability, wear resistance, and low fuel consumption performance by having a configuration that satisfies the relationship of "A × B / C > 0.5". That is, the parameter of "A × B / C > 0.5" does not define the problem (objective). The problem of the present application is to improve the overall performance of handling stability, wear resistance, and low fuel consumption performance, and as a solution means therefor, it has a configuration that satisfies the said parameter.

[0011] The above tire has a tire member composed of a rubber composition. Hereinafter, the chemicals that can be used in the above rubber composition will be described.

[0012] The above rubber composition contains a rubber component. Here, the rubber component is a component that contributes to crosslinking. Generally, a polymer having a weight average molecular weight (Mw) of 10,000 or more, and a polymer component that is not extracted by acetone corresponds to the rubber component. The elastomer component is in a solid state at normal temperature (25°C).

[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 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 more favorably.

[0014] In addition, in this specification, the weight average molecular weight (Mw) can be determined by standard polystyrene conversion based on the measured value by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation). Also, in the case of a polymer having a modifying group, since the modifying group and the silica gel of the column interact with each other and an accurate Mw cannot be obtained, Mw is measured before the modification treatment is carried out.

[0015] The rubber component that can be used in the above rubber composition may be an unmodified rubber or a modified rubber. Examples of the modified rubber include rubbers having a functional group that interacts with a filler such as silica. For example, a terminal-modified rubber (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, etc. are mentioned.

[0016] Examples of the functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imide group, a hydrazo group, an azo group, a diazo group, a carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group, an epoxy group, etc. These functional groups may have substituents. Among them, an amino group (preferably an amino group in which a hydrogen atom of the amino group is substituted with an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), and an alkoxysilyl group (preferably an alkoxysilyl group having 1 to 6 carbon atoms) are preferable.

[0017] Examples of the rubber component include diene rubbers. Examples of the diene rubber include isoprene rubbers, butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), etc. In addition, examples of the rubber component also include butyl rubbers, fluororubbers, etc. These may be used alone or in combination of two or more. Further, these rubber components may be subjected to modification treatment or hydrogenation treatment, and extended rubbers extended with oils, resins, liquid rubber components, etc. may also be used. Among them, it is preferable to contain at least one of isoprene rubbers, BR, and SBR, and it is more preferable to contain at least an isoprene rubber.

[0018] Examples of isoprene rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, denatured NR, denatured IR, etc. As NR, for example, those commonly used in the rubber industry such as SIR20, RSS#3, TSR20, etc. can be used. IR is not particularly limited, and for example, those commonly used in the rubber industry such as IR2200, etc. can be used. Examples of modified NR include deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc. Examples of denatured NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. Examples of denatured IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, etc. These may be used alone or in combination of two or more.

[0019] In the above rubber composition, the content of isoprene rubber in 100% by mass of the rubber component is preferably 50% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and may be 100% by mass. When within the above range, the effect tends to be obtained more favorably.

[0020] 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 spectroscopy analysis.

[0021] When BR is a single type, the cis amount of BR means the cis amount of that BR, and when there are multiple types, it means the average cis amount. The average cis amount of BR can be calculated by {Σ(content of each BR × cis amount of each BR)} / total content of all BRs. For example, in 100% by mass of the rubber component, when the BR with a cis amount of 90% by mass is 20% by mass and the 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)).

[0022] In addition, either non-modified BR or modified BR can be used. Examples of the modified BR include modified BR into which a functional group similar to that of modified rubber has been introduced. Also, hydrogenated butadiene polymer (hydrogenated BR) can be used as BR.

[0023] As the BR, for example, products of Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., etc. can be used.

[0024] When the rubber composition contains BR, the content of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more, and is preferably 50% by mass or less, more preferably 40% by mass or less, still more preferably 30% by mass or less. When within the above range, the effect tends to be obtained more favorably.

[0025] SBR is not particularly limited. For example, emulsion polymerization styrene butadiene rubber (E-SBR), solution polymerization styrene butadiene rubber (S-SBR), etc. can be used. These may be used alone or in combination of two or more.

[0026] The styrene content of SBR is preferably 5% by mass or more, more preferably 20% by mass or more, still more preferably 25% by mass or more. The styrene content is preferably 60% by mass or less, more preferably 40% by mass or less, still more preferably 35% by mass or less. When within the above range, the effect tends to be obtained more favorably. In the present specification, the styrene content 1 can be measured by 1H-NMR measurement.

[0027] The amount of styrene in SBR means the amount of styrene in the case where SBR is one type, and means the average amount of styrene in the case of multiple types. The average styrene content of SBR can be calculated by {Σ(content of each SBR × styrene content of each SBR)} / total content of all SBRs. For example, when in 100% by mass of the rubber component, 85% by mass of SBR has a styrene content of 40% by mass and 5% by mass of SBR has a styrene content of 25% by mass, the average styrene content of SBR is 39.2% by mass (=(85×40 + 5×25) / (85 + 5)).

[0028] The vinyl bond content of SBR is preferably 3% by mass or more, more preferably 5% by mass or more, and still more preferably 7% by mass or more. When the vinyl bond content is within the range of preferably 50% by mass or less, more preferably 40% by mass or less, and still more preferably 30% by mass or less, the effects tend to be obtained more favorably. In this specification, the vinyl bond content (1,2 - bonded butadiene unit content) can be measured by infrared absorption spectroscopy.

[0029] The vinyl content (1,2 - bonded butadiene unit content) of SBR is the ratio of vinyl bonds when the total mass of the butadiene part in SBR is set to 100 (unit: % by mass), and vinyl content [% by mass] + cis content [% by mass] + trans content [% by mass] = 100 [% by 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 [% by mass] - styrene content of each SBR [% by mass]) × vinyl content of each SBR [% by mass]} / Σ{content of each SBR × (100 [% by mass] - styrene content of each SBR [% by mass])}. For example, when in 100 parts by mass of the rubber component, 75 parts by mass of SBR has a styrene content of 40% by mass and a vinyl content of 30% by mass, 15 parts by mass of SBR has a styrene content of 25% by mass and a vinyl content of 20% by mass, and the remaining 10 parts by mass are other than SBR, the average vinyl content of SBR is 28% by mass (={75×(100 [% by mass] - 40 [% by mass])×30 [% by mass] + 15×(100 [% by mass] - 25 [% by mass])×20 [% by mass])} / {75×(100 [% by mass] - 40 [% by mass]) + 15×(100 [% by mass] - 25 [% by mass])}.

[0030] Either non-modified SBR or modified SBR can be used. Examples of the modified SBR include those with functional groups similar to modified rubbers introduced. Also, as SBR, hydrogenated styrene-butadiene copolymer (hydrogenated SBR) can be used.

[0031] 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.

[0032] When the above rubber composition contains SBR, the content of SBR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, still more preferably 30% by mass or less. When within the above range, the effect tends to be obtained more favorably.

[0033] Incidentally, the raw materials (monomers) of synthetic rubbers such as SBR and BR may be petroleum-derived or recycled from rubber products such as tires and non-rubber products such as polystyrene. The monomers obtained by recycling (recycled monomers) are not particularly limited, and examples include recycled butadiene and recycled aromatic vinyl. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl is not particularly limited, and examples include styrene. Among them, it is preferable to use recycled butadiene (recycled butadiene) and / or recycled styrene (recycled styrene) as raw materials.

[0034] The method for producing the recycled monomer is not particularly limited, and for example, it can be synthesized from recycled naphtha obtained by decomposing rubber products such as tires. Also, the method for producing recycled naphtha is not particularly limited, and for example, rubber products such as tires may be decomposed under high temperature and high pressure, decomposed by microwaves, or extracted after mechanical pulverization.

[0035] Furthermore, the raw materials (monomers) of synthetic rubbers such as SBR and BR may be derived from biomass. The monomer derived from biomass (biomass monomer) is not particularly limited, and examples include biomass-derived butadiene and biomass-derived 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. Also, the method for producing the biomass monomer is not particularly limited, and for example, it can be obtained by biological and / or chemical and / or physical conversion of animals and plants. Fermentation by microorganisms is typical of biological conversion, and chemical and / or physical conversion includes those by catalysts, high heat, high pressure, electromagnetic waves, supercritical fluids, and combinations thereof. Examples of the biomass sources of these monomers include sugars, wood, plant residues after obtaining useful components, ethanol derived from plants, and biomass naphtha.

[0036] The polymer synthesized from the biomass monomer component (biomass polymer) is not particularly limited, and examples include polybutadiene rubber synthesized from biomass-derived butadiene, and aromatic vinyl / butadiene copolymer synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl. Examples of the aromatic vinyl / butadiene copolymer include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0037] 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.

[0038] pMC is the ratio of the 14 C concentration of the sample to the 14 C concentration of the standard modern reference, and this value is used as an index indicating the biomass ratio of the compound (rubber). The significance of this value is described below.

[0039] In one mole (6.02×10 23 pieces) of carbon atoms, there are approximately 6.02×10 11 pieces of 14 C, which is about one trillionth of the normal carbon atoms. 14 14 C is called a radioactive isotope, and its half-life is 5730 years and it decreases regularly. It takes 226,000 years for all of these to decay. Therefore, after carbon dioxide in the atmosphere and the like are taken up and fixed by plants and the like, in fossil fuels such as coal, oil, and natural gas that are considered to have passed more than 226,000 years, 14 all of the 14 C elements contained in them at the beginning of fixation have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas do not contain 14 any 14 C elements. Therefore, chemical substances produced from these fossil fuels as raw materials also do not contain 14 any 14 C elements.

[0040] On the other hand, 14 14 C is constantly generated by nuclear reactions of cosmic rays in the atmosphere, and the decrease due to radioactive decay is balanced. In the earth's atmospheric environment, 14 the amount of 14 C is a certain amount. Therefore, the 14 14 C concentration of substances derived from biomass resources circulating in the current environment is about 1×10 -12It becomes a value on the order of mol%. Therefore, by using the difference between these values, the ratio (biomass ratio) of the compound derived from natural resources (compound derived from biomass resources) in a certain compound (rubber) can be calculated.

[0041] This 14 C is generally measured as follows. Using accelerator mass spectrometry based on a tandem accelerator, 13 C concentration ( 13 C / 12 C), 14 C concentration ( 14 C / 12 C) is measured. In the measurement, 14 As a modern standard reference for the concentration of 14 C, the concentration of 14 C in the circulating carbon in nature in 1950 is adopted. As a specific standard substance, 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 13 C per gram of carbon) is separated for each carbon isotope, 14 C 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 value of the standard 14 C concentration (100%). The ratio of this value to the value of the sample actually measured is the pMC value.

[0042] Therefore, if the rubber is manufactured from a substance derived entirely from biomass (natural system), although there are regional differences, it will show a value of approximately 110 pMC (currently, in the normal state, it often does not reach 100). On the other hand, for chemical substances derived from fossil fuels such as petroleum, when the concentration of 14 C is measured, it will show approximately 0 pMC (for example, 0.3 pMC). This value corresponds to a biomass ratio of 0% mentioned above.

[0043] From the above, it is preferable in terms of environmental protection to use a material such as rubber with a high pMC value, that is, a material such as rubber with a high biomass ratio, in the rubber composition.

[0044] The above rubber composition contains at least recycled carbon black (recycled carbon black) as carbon black. The carbon black may be used alone or in combination of two or more. In this specification, recycled carbon black means carbon black recovered by subjecting a rubber product containing used carbon black to pyrolysis.

[0045] Examples of recycled carbon black include recycled carbon black produced through pyrolysis of waste tires. The pyrolysis of waste tires can be carried out by known methods, such as pyrolysis methods at a temperature of 650°C or higher. Specifically, examples include recycled carbon black obtained by pyrolysis of tires and containing hydroxyl groups and / or carboxyl groups on its surface, as disclosed in European Patent Application Publication No. 3173251. The recycled carbon black may be used alone or in combination of two or more.

[0046] The average primary particle diameter of the recycled carbon black is preferably 30 nm or more, more preferably 35 m or more, and preferably 65 nm or less, more preferably 60 nm or less, and still more preferably 55 nm or less. When within the above range, the effect tends to be obtained more favorably. In this specification, the average primary particle diameter of carbon black can be observed by a transmission or scanning electron microscope, and more than 400 primary particles of carbon black observed in the field of view are measured, and the average is obtained thereby.

[0047] Commercially available products can be used as recycled carbon black, for example, the product named PB365 manufactured by Enrestec. PB365 is recycled carbon black produced through pyrolysis of waste tires, and N2SA is 76 m 2It is / g. Also, PB365 contains about 17% by mass of ash.

[0048] In the above rubber composition, the content of recycled carbon black is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, still more preferably 30 parts by mass or more, particularly preferably 40 parts by mass or more, and preferably 150 parts by mass or less, more preferably 100 parts by mass or less, still more preferably 80 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.

[0049] The above rubber composition may contain carbon black other than recycled carbon black (hereinafter also referred to as general-purpose carbon black). Such general-purpose carbon black (new carbon black) is not particularly limited, but examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. As commercially available products, products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin Nippon Carbon Co., Ltd., Columbian Carbon Co., etc. can be used. These may be used alone or in combination of two or more. Also, in addition to carbon black made from conventional mineral oil and the like as raw materials, carbon black made from biomass materials such as lignin can also be used.

[0050] The nitrogen adsorption specific surface area (N2SA) of the general-purpose carbon black is preferably 5 m 2 / g or more, more preferably 10 m 2 / g or more, still more preferably 15 m 2 / g or more. Also, the above N2SA is preferably 130 m 2 / g or less, more preferably 120 m 2 / g or less, still more preferably 100 m 2 / g or less. When within the above range, the effect tends to be obtained more favorably. Note that the nitrogen adsorption specific surface area of carbon black is determined according to JIS K6217-2:2001.

[0051] The average primary particle diameter of the general-purpose carbon black is preferably 10 nm or more, more preferably 30 nm or more, and preferably 100 nm or less, more preferably 80 nm or less, still more preferably 70 nm or less. When it is within the above range, the effect tends to be obtained better.

[0052] In the above rubber composition, the content of the general-purpose carbon black is preferably 1 part by mass or more, more preferably 3 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 preferably 100 parts by mass or less, more preferably 50 parts by mass or less, still more preferably 30 parts by mass or less. When it is within the above range, the effect tends to be obtained better.

[0053] In the above rubber composition, the content A of the carbon black (total content of the recycled carbon black and other carbon blacks) is preferably 2 parts by mass or more, more preferably 20 parts by mass or more, still more preferably 30 parts by mass or more, based on 100 parts by mass of the rubber component, and preferably 150 parts by mass or less, more preferably 100 parts by mass or less, still more preferably 80 parts by mass or less. When it is within the above range, the effect tends to be obtained better.

[0054] When the carbon black contains 30 parts by mass or more, particularly 30 parts by mass or more, the mechanism by which more effects are obtained is not clear. However, when the recycled carbon black is not blended, the reduction in reinforcement is significant. Therefore, it is considered that by blending a predetermined amount of the carbon black containing the recycled carbon black, a remarkable effect of improving the reinforcement is exhibited. Accordingly, it is presumed that the comprehensive performance of the handling stability, wear resistance, and low fuel consumption is improved.

[0055] In the above rubber composition, the content of recycled carbon black in 100% by mass of carbon black (in 100% by mass of the total amount of recycled carbon black and other carbon blacks) is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more. The upper limit is not particularly limited and may be 100% by mass, but is preferably 95% by mass or less, more preferably 90% by mass or less. When within the above range, the effect tends to be obtained more favorably.

[0056] In the above rubber composition, the average primary particle diameter of carbon black (the average primary particle diameter of the entire carbon black) is preferably 10 nm or more, more preferably 30 nm or more, and is preferably 100 nm or less, more preferably 60 nm or less, still more preferably 40 nm or less. When within the above range, the effect tends to be obtained more favorably.

[0057] In addition, in this specification, the average primary particle diameter of carbon black (the average primary particle diameter of the entire carbon black) can be calculated by {Σ (content of each carbon black × average primary particle diameter of each carbon black)} / total content of all carbon blacks. For example, when 10 parts by mass of a general-purpose carbon black with an average primary particle diameter of 66 nm and 40 parts by mass of recycled carbon black with an average primary particle diameter of 35 nm are used per 100 parts by mass of the rubber component, the average primary particle diameter of the entire carbon black is 41 nm (=(66×10 + 35×40) / (10 + 40)).

[0058] The mechanism by which more effects are obtained in a predetermined range, particularly when the average primary particle diameter of the entire carbon black is 30 nm or more and 60 nm or less, is not clear. However, the larger the average primary particle diameter of the recycled carbon black, the greater the decrease in reinforcing property when not compounded. Therefore, it is considered that by compounding carbon black containing recycled carbon black, a remarkable effect of improving the reinforcing property is exhibited. Accordingly, it is inferred that the comprehensive performance of handling stability, abrasion resistance, and low fuel consumption is improved.

[0059] The above rubber composition may contain a filler other than 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, etc., biochar (BIO CHAR); poorly dispersible fillers, etc. can be mentioned. Among them, silica is preferred from the viewpoint of obtaining more effects.

[0060] In the above rubber composition, the content of the filler (total amount of fillers such as carbon black, silica, etc.) is preferably 2 parts by mass or more, more preferably 30 parts by mass or more, still more preferably 50 parts by mass or more, and preferably 200 parts by mass or less, more preferably 150 parts by mass or less, still more preferably 100 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.

[0061] In the above rubber composition, 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., those 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 minerals such as quartz, or a raw material derived from organisms such as rice husks (for example, silica using biomass materials such as rice husks as raw materials), or silica recycled from products containing silica may also be used. Among them, hydrous silica prepared by the wet method is preferred because it has many silanol groups. These silicas may be used alone or in combination of two or more.

[0062] Silica using biomass materials as raw materials can be obtained, for example, by extracting 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.

[0063] 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 these, silica recovered from electronic components such as semiconductors or tires is preferable.

[0064] When silica crystallizes, it becomes insoluble 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.).

[0065] Amorphous silica extracted from rice husks can be those commercially available from companies such as Wilmar.

[0066] When the above rubber composition contains silica, the content of silica is preferably 2 parts by mass or more, more preferably 6 parts by mass or more, still more preferably 20 parts by mass or more, and preferably 200 parts by mass or less, more preferably 150 parts by mass or less, still more preferably 100 parts by mass or less, based on 100 parts by mass of the rubber component. When within the above range, the effects tend to be obtained more favorably.

[0067] The nitrogen adsorption specific surface area (N2SA) of silica is preferably 50 m 2 / g or more, more preferably 100 m 2 / g or more, still more preferably 150 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 effects tend to be obtained more favorably. Note that the N2SA of silica is a value measured by the BET method in accordance with ASTM D3037-93.

[0068] Examples of the hardly dispersible filler include microfibrillated plant fibers, short fibrous cellulose, gel-like compounds, etc. Among them, microfibrillated plant fibers are preferred.

[0069] As the above-mentioned microfibrillated plant fibers, 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 such as rice straw, wheat straw, and thinned wood, and cellulose produced by organisms such as jellyfish and acetic acid bacteria. These microfibrillated plant fibers may be used alone or in combination of two or more.

[0070] In the present specification, the cellulose microfibril typically means a cellulose fiber having an average fiber diameter within the range of 10 μm or less, and more typically, a cellulose fiber having a fine structure with an average fiber diameter of 500 nm or less formed by an aggregation of cellulose molecules. A typical cellulose microfibril is formed, for example, as an aggregate of cellulose fibers having the above-mentioned average fiber diameter.

[0071] When the above rubber composition contains a hardly dispersible filler, the content of the hardly dispersible filler is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, still more preferably 20 parts by mass or less, and particularly preferably 10 parts by mass or less. When within the above range, the effect tends to be obtained more favorably.

[0072] When the above rubber composition contains silica, it is preferably further contained with 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. of the sulfide series, 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, mercapto series such as NXT and NXT-Z manufactured by Momentive, vinyl series such as vinyltriethoxysilane and vinyltrimethoxysilane, amino series such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane, glycidoxy series such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane, nitro series such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane, chloro series 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., Azmax Co., Ltd., Toray Dow Corning Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

[0073] In the above rubber composition, 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 within the above range, the effect tends to be obtained more favorably.

[0074] The above rubber composition contains a nitrogen compound. The above nitrogen compound is not particularly limited as long as it is a compound having nitrogen in the molecule. The nitrogen compound may be used alone or in combination of two or more.

[0075] In the above rubber composition, the content of the above nitrogen compound is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, still more preferably 30 parts by mass or more, and particularly preferably 33 parts by mass or more with respect to 100 parts by mass of carbon black. The upper limit of the content is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, still more preferably 50 parts by mass or less. When within the above range, the effect tends to be obtained more favorably.

[0076] From the viewpoint of obtaining a better effect, it is desirable that the nitrogen compound contains an isocyanate compound.

[0077] When an isocyanate compound is included, the mechanism by which a better effect is obtained is not clear, but isocyanate has a high reactivity with a hydroxyl group. Therefore, it is presumed that the affinity with the polymer is improved, the reinforcing property and the dispersibility of carbon black are improved, and the overall performance of handling stability, wear resistance and low fuel consumption is improved.

[0078] Examples of the isocyanate compound include compounds having at least one isocyanate group. Compounds having at least one isocyanate group include monofunctional isocyanates and polyfunctional isocyanates. Among them, monofunctional isocyanates are desirable from the viewpoint of obtaining a better effect.

[0079] Examples of monofunctional isocyanates include methyl isocyanate, ethyl isocyanate, propyl isocyanate, butyl isocyanate, octyl isocyanate, decyl isocyanate, octadecyl isocyanate, stearyl isocyanate, cyclohexyl isocyanate, phenyl isocyanate, benzyl isocyanate, p-chlorophenyl isocyanate, p-nitrophenyl isocyanate, (R)-(+)-α-methylbenzyl isocyanate, (R)-(+)-1-phenylethyl isocyanate, (S)-(-)-1-phenylethyl isocyanate, p-toluenesulfonyl isocyanate, and the like. Among them, from the viewpoint of obtaining better effects, benzyl isocyanate and (R)-(+)-α-methylbenzyl isocyanate are preferred, and benzyl isocyanate is more preferred.

[0080] Examples of polyfunctional isocyanates include aromatic polyisocyanates, aliphatic polyisocyanates, araliphatic polyisocyanates, alicyclic polyisocyanates, and the like.

[0081] Examples of aromatic polyisocyanates include 1,3-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4',4''-triphenylmethane triisocyanate, and the like.

[0082] Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (also known as HDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, and the like.

[0083] Examples of the araliphatic polyisocyanate include ω,ω'-diisocyanate-1,3-dimethylbenzene, 1,4-tetramethylxylylene diisocyanate, and the like.

[0084] Examples of the alicyclic polyisocyanate include 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,4-bis(isocyanatomethyl)cyclohexane, and the like.

[0085] In the above rubber composition, the content of the above isocyanate compound is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, still more preferably 30 parts by mass or more, and particularly preferably 33 parts by mass or more, based on 100 parts by mass of carbon black. The upper limit of the content is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, and still more preferably 50 parts by mass or less. When within the above range, the effect tends to be obtained more favorably. In addition, the content of the above monofunctional isocyanate and the content of benzyl isocyanate are also preferably in the same range.

[0086] From the viewpoint of obtaining a better effect, the above nitrogen compound preferably contains a compound represented by the following formula (A).

Chemical formula

[0087] Ring Q 1 is preferably a benzene ring which may be substituted with 1 to 3 groups selected from the group consisting of a halogen atom, a hydroxyl group, an amino group, a C 1-4 alkyl group, a C 1-4 alkoxy group, and an acetyl group; more preferably, it is a benzene ring which may be substituted with 1 to 3 groups selected from the group consisting of a halogen atom, a C 1-4 alkyl group, and a C 1-4 alkoxy group.

[0088] Ring Q 2 is preferably an imidazole ring which may be substituted with 1 to 2 groups selected from the group consisting of a halogen atom, a hydroxyl group, an amino group, a C 1-4 alkyl group, a C 1-4 alkoxy group, and an acetyl group; more preferably, it is an imidazole ring which may be substituted with 1 to 2 groups selected from the group consisting of a halogen atom, an amino group, and a C 1-4 alkyl group; still more preferably, it is an imidazole ring substituted with 1 to 2 C 1-4 alkyl groups. Note that the bond to the carbonyl group on the imidazole ring may be either a carbon atom or a nitrogen atom constituting the ring.

[0089] In the above rubber composition, the content of the compound represented by the above formula (A) is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, still more preferably 30 parts by mass or more, and particularly preferably 33 parts by mass or more, based on 100 parts by mass of carbon black. The upper limit of the content is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, and still more preferably 50 parts by mass or less. When within the above range, the effect tends to be obtained more favorably.

[0090] When bonding carbon black and the compound represented by the above formula (A), the amide bond of the compound represented by the formula (A) undergoes a hydrolysis reaction and cleavage during the kneading process, and the compound having an amino group resulting therefrom binds to the functional group on the carbon black surface. On the other hand, the carboxylic acid represented by the following formula (A1) generated as a result of hydrolysis can be recovered by Soxhlet extraction of the vulcanized rubber.

Chemical formula

[0091] Ring Q 2 is preferably an imidazole ring which may be substituted with 1 to 2 groups selected from the group consisting of a halogen atom, a hydroxyl group, an amino group, a C 1-4 alkyl group, a C 1-4 alkoxy group, and an acetyl group; more preferably an imidazole ring which may be substituted with 1 to 2 groups selected from the group consisting of a halogen atom, an amino group, and a C 1-4 alkyl group; still more preferably an imidazole ring substituted with 1 to 2 C 1-4 alkyl groups. The bond to the carbonyl group on the imidazole ring may be either a carbon atom or a nitrogen atom constituting the ring.

[0092] When the vulcanized rubber composition is subjected to Soxhlet extraction at 80°C for 72 hours using acetone as a solvent in accordance with Method A described in JIS K 6229:2015 "Rubber - Method for Determination of Solvent Extracts (Quantitative)", the extraction amount of the compound represented by formula (A1) is preferably 0.10 part by mass or more, more preferably 0.20 part by mass or more, still more preferably 0.30 part by mass or more, and particularly preferably 0.40 part by mass or more with respect to 100 parts by mass of carbon black. Further, the upper limit of the extraction amount of the compound represented by formula (A1) is not particularly limited, but is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, and still more preferably 30 parts by mass or less.

[0093] In the above rubber composition, from the viewpoint of obtaining more effects, it is desirable that the recycled carbon black and the nitrogen compound are those in which the recycled carbon black has been surface - treated in advance with the nitrogen compound (hereinafter, also referred to as nitrogen - treated recycled carbon black).

[0094] When nitrogen - treated recycled carbon black is included, the mechanism by which more effects are obtained is not clear, but by using the pre - treated nitrogen - treated recycled carbon black, the reaction between the carbon black surface and the nitrogen compound is likely to occur. Therefore, it is presumed that the affinity with the polymer is improved, the reinforcing property and the dispersibility of the carbon black are improved, and the overall performance of handling stability, abrasion resistance and low fuel consumption is improved.

[0095] The above rubber composition 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 (in a liquid state) at normal temperature (25°C) and plasticizers that are solid at normal temperature (25°C). Examples of plasticizers include resin components, oils, liquid polymers, ester-based plasticizers, etc. These plasticizers may be derived from petroleum, may be derived from biomass, or may be derived from naphtha recycled from rubber products or non-rubber products. Also, low-molecular-weight hydrocarbon components obtained by pyrolyzing 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.

[0096] Specific examples of the above plasticizers include oils, liquid polymers, resins, etc. These may be used alone or in combination of two or more.

[0097] Examples of oils include, for example, process oils, vegetable oils, animal oils, etc. Examples of process oils include paraffinic process oils (mineral oils), naphthenic process oils, aromatic process oils, etc. Specific examples of process oils include, for example, MES (Mild Extract Solvated), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), RAE (Residual Aromatic Extract), etc. Also, process oils with a low content of polycyclic aromatic (PCA) compounds can be used for environmental measures. Examples of the low-PCA content process oils include MES, TDAE, heavy naphthenic oils, etc. Also, from the perspective of life cycle assessment, waste oils after being used in rubber mixers or engines, or refined waste cooking oils used in restaurants may be used.

[0098] 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 rosin, and the like. Further, as vegetable oils, there may be mentioned 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, heat-polymerized oils obtained by heat-polymerizing the above oils, oxidative polymerized oils obtained by oxidizing the above oils, waste cooking oils recovered from those used as edible oils, and the like. Note that the vegetable oil may be liquid or solid at normal temperature (25°C). These vegetable oils may be used alone or in combination of two or more.

[0099] The vegetable oil according to this embodiment preferably contains acylglycerol, and more preferably contains triacylglycerol. In this specification, acylglycerol refers to a compound in which a hydroxy group of glycerin and a fatty acid are ester-bonded. The acylglycerol is not particularly limited, and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Further, the acylglycerol may be a monomer, a dimer, or a multimer of trimer or higher. Note that acylglycerols of dimer or higher can be obtained by heat polymerization, oxidative polymerization, or the like. Also, the acylglycerol may be liquid or solid at normal temperature (25°C).

[0100] The method for confirming whether the acylglycerol is contained in the rubber composition is not particularly limited, but 1 it can be confirmed by 1H-NMR measurement. For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at normal temperature (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.

[0101] 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.

[0102] Among them, as the fatty acid, it is desirable to contain a fatty acid with few double bonds, that is, a saturated fatty acid or a monounsaturated fatty acid, and oleic acid is preferred. As the vegetable oil containing such a fatty acid, for example, a vegetable oil containing a saturated fatty acid or a monounsaturated fatty acid may be used, or a vegetable oil subjected to modification such as transesterification may be used. Further, in order to produce such a vegetable oil containing a fatty acid, plants may be improved by variety improvement, genetic recombination, genome editing, etc.

[0103] As the oil, for example, those commercially available from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Co., Ltd., Olisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kogyo Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0104] 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. Also, hydrogenated products thereof can be used.

[0105] The weight average molecular weight (Mw) in terms of polystyrene measured by gel permeation chromatography (GPC) of the liquid diene polymer is preferably 1.0×10 3 ~5.0×10 4 and more preferably 3.0×10 3 ~1.5×10 4 . The lower limit or the upper limit of Mw of the liquid diene polymer may also be 4500 or 8500. In the present specification, Mw of the liquid diene polymer is a polystyrene-converted value measured by gel permeation chromatography (GPC).

[0106] Examples of the liquid diene polymer include products of Sartomer Company, Kuraray Co., Ltd., etc.

[0107] As the above resin, as a tire compound, resins (resins) 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.

[0108] When using a resin that is solid at normal temperature, the softening point of the above resin is preferably 50°C or higher, more preferably 55°C or higher, still more preferably 60°C or higher, and particularly preferably 85°C or higher. Also, it is preferably 160°C or lower, more preferably 150°C or lower, still more preferably 140°C or lower, and particularly preferably 100°C or lower. When within the above range, the effect tends to be obtained more favorably. When the resin is liquid at normal temperature, the softening point is preferably 20°C or lower, preferably 10°C or lower, and preferably 0°C or lower. In the case of a hydrogenated resin, it is desirable that the softening point is the same as above. Note that the softening point of the above resin is the temperature at which the ball drops, measured with a ring and ball softening point measuring device for the softening point defined in JIS K6220-1:2001.

[0109] 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.

[0110] 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 contained in the skeleton other than coumarone and indene include styrene, α-methylstyrene, methyl indene, vinyl toluene, and the like.

[0111] The above-mentioned coumarone resin is a resin containing coumarone as the main monomer component constituting the resin skeleton (main chain).

[0112] The above-mentioned indene resin is a resin containing indene as the main monomer component constituting the resin skeleton (main chain).

[0113] 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.

[0114] 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.

[0115] Examples of the above-mentioned petroleum resin include C5-based resin, C9-based resin, C5 / C9-based resin, dicyclopentadiene (DCPD) resin, C9 / DCPD resin, and hydrogenated products thereof. Among them, DCPD resin, hydrogenated DCPD resin, C9 / DCPD resin, and C9 / hydrogenated DCPD resin are preferred.

[0116] The above terpene resin is a polymer containing terpenes as constituent units. For example, there are polyterpene resins obtained by polymerizing terpene compounds, aromatic modified terpene resins obtained by polymerizing terpene compounds and aromatic compounds, and the like. Examples of aromatic modified terpene resins include terpene phenol resins using terpene compounds and phenolic compounds as raw materials, terpene styrene resins using terpene compounds and styrene compounds as raw materials, and terpene phenol styrene resins using terpene compounds, phenolic compounds and styrene compounds as raw materials. Examples of terpene compounds include α-pinene, β-pinene, etc., examples of phenolic compounds include phenol, bisphenol A, etc., and examples of aromatic compounds include styrene compounds (styrene, α-methylstyrene, etc.). Among them, aromatic modified terpene resins are preferred.

[0117] The above acrylic resin is a polymer containing acrylic monomers as constituent units. For example, there are styrene acrylic resins such as styrene acrylic resins obtained by copolymerizing an aromatic vinyl monomer component and an acrylic monomer component and having a carboxyl group. Among them, a solventless carboxyl group-containing styrene acrylic resin can be preferably used.

[0118] 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 Industry Co., Ltd., etc. can be used.

[0119] 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.

[0120] 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]

[0121] 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.

[0122] Examples of vinyl monomers include aromatic vinyl compounds such as styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-tert-butylstyrene, 5-t-butyl-2-methylstyrene, vinyl ethylbenzene, divinylbenzene, trivinylbenzene, divinylnaphthalene, tert-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl)dimethylaminoethyl ether, N,N-dimethylaminoethylstyrene, N,N-dimethylaminomethylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-t-butylstyrene, 3-t-butylstyrene, 4-t-butylstyrene, vinylxylene, vinylnaphthalene, vinyltoluene, vinylpyridine, diphenylethylene, and tertiary amino group-containing diphenylethylene, and conjugated diene compounds such as butadiene and isoprene. These may be used alone or in combination of two or more. Among them, butadiene is preferred. That is, as the farnesene-vinyl monomer copolymer, a copolymer of farnesene and butadiene (farnesene-butadiene copolymer) is preferred.

[0123] In the farnesene-vinyl monomer copolymer, the copolymerization ratio by mass (farnesene / vinyl monomer) of farnesene and the vinyl monomer is preferably 40 / 60 to 90 / 10.

[0124] Farnesene-based polymers can preferably be those having a weight average molecular weight (Mw) of 3000 or more and 300,000 or less. The Mw of the farnesene-based polymer is preferably 8000 or more, more preferably 10,000 or more, and preferably 100,000 or less, more preferably 60,000 or less, and still more preferably 50,000 or less. When within the above range, the effects tend to be more preferably obtained.

[0125] The farnesene-based polymer may be either in a liquid state or a solid state at room temperature (25°C). Among them, a liquid farnesene-based polymer in a liquid state at room temperature (25°C) is desirable.

[0126] When the above rubber composition contains a plasticizer, the content of the plasticizer (total amount of the plasticizer) is preferably 20 parts by mass or more, more preferably 35 parts by mass or more, still more preferably 40 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, still more preferably 50 parts by mass or less. When it is within the above range, the effect tends to be obtained more favorably. Note that the content of the plasticizer also includes the amount of oil and resin contained in the oil-extended rubber and resin-extended rubber.

[0127] In the above rubber composition, the content of the solid plasticizer in a solid state at normal temperature (25°C) is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, still more preferably 20 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 40 parts by mass or less, still more preferably 30 parts by mass or less. When it is within the above range, the effect tends to be obtained more favorably. Note that the content of the above resin in a solid state at normal temperature (25°C) is preferably in the same range.

[0128] In the above rubber composition, the content of the liquid plasticizer in a liquid state at normal temperature (25°C) is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, still more preferably 20 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 40 parts by mass or less, still more preferably 30 parts by mass or less. When it is within the above range, the effect tends to be obtained more favorably. Note that the content of the liquid plasticizer also includes the amount of oil contained in the oil-extended rubber and the amount of liquid resin of the resin-extended rubber extended with the liquid resin. The content of the oil in a liquid state at normal temperature (25°C) is preferably in the same range.

[0129] From the viewpoints of crack resistance, ozone resistance, etc., the above rubber composition preferably contains an antioxidant.

[0130] 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, etc. can be used.

[0131] In the above rubber composition, the content of the anti-aging agent is preferably 0.2 parts by mass or more, more preferably 0.7 parts by mass or more, and still more preferably 1.0 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, and more preferably 6.0 parts by mass or less.

[0132] The above rubber composition preferably contains stearic acid. In the above rubber composition, the content of stearic acid is preferably 0.5 parts by mass or more, more preferably 2.0 parts by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, based on 100 parts by mass of the rubber component.

[0133] 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.

[0134] The above rubber composition preferably contains zinc oxide. In the above rubber composition, the content of zinc oxide is preferably 0.5 parts by mass or more, more preferably 2.0 parts by mass or more, and preferably 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.

[0135] As the zinc oxide, conventionally known ones can be used. For example, products of Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusuitech Co., Ltd., Shoindo Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used.

[0136] The above rubber composition may be blended with wax. In the above rubber composition, the content of wax is preferably 0.5 parts by mass or more, more preferably 1.2 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.

[0137] The wax is not particularly limited, and any wax commonly used in the tire industry can be preferably used. For example, petroleum waxes, mineral waxes, synthetic waxes, plant-derived waxes, etc. can be mentioned. Among them, petroleum waxes and plant-derived waxes are preferred, and petroleum waxes are more preferred. Examples of plant-derived waxes include rice wax, carnauba wax, candelilla wax, etc. Examples of petroleum waxes include paraffin wax, microcrystalline wax, and their 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 Shinko 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.

[0138] In the above rubber composition, it is preferable to compound sulfur in terms of forming appropriate crosslinked chains in the polymer chain and imparting good performance.

[0139] In the above rubber composition, the sulfur content is preferably 1.0 part by mass or more, more preferably 1.5 part by mass or more, still more preferably 2.0 part by mass or more, based on 100 parts by mass of the rubber component. The content is preferably 7.0 part by mass or less, more preferably 5.0 part by mass or less, still more preferably 4.0 part by mass or less.

[0140] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, soluble sulfur, etc., which are generally used in the rubber industry. As commercially available products, products of Tsuruami Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexis Co., Ltd., Nippon Karyu Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

[0141] The above rubber composition preferably contains a vulcanization accelerator. In the above rubber composition, the content of the vulcanization accelerator is not particularly limited and may be freely determined according to the desired vulcanization rate and crosslink density. However, based on 100 parts by mass of the rubber component, it is preferably 0.1 part by mass or more, more preferably 0.3 part by mass or more, and still more preferably 0.5 part by mass or more. The upper limit is preferably 8.0 parts by mass or less, more preferably 5.0 parts by mass or less, and still more preferably 4.0 parts by mass or less.

[0142] 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.

[0143] In addition to the above components, the above rubber composition may be appropriately blended with compounding agents commonly used in the tire industry, such as mold release agents and other materials.

[0144] In this specification, various materials containing carbon atoms (such as rubber, oil, resin, vulcanization accelerator, anti-aging agent, surfactant, etc.) may be derived from carbon dioxide in the atmosphere. As a method for obtaining the above-mentioned blend from carbon dioxide, carbon dioxide may be directly converted, or methane obtained through a methanation process of synthesizing methane from carbon dioxide may be converted.

[0145] The above rubber composition is used for tire members. In addition to the above components, the above rubber composition may be appropriately blended with compounding agents generally used in the tire industry, such as materials such as mold release agents.

[0146] The above rubber composition can be produced, for example, by kneading the above components using a rubber kneading device such as an open roll or a Banbury mixer, and then vulcanizing.

[0147] As the kneading conditions, in the base kneading step of kneading additives other than the crosslinking agent (vulcanizing agent) and the vulcanization accelerator, the kneading temperature is preferably 100 °C or higher, more preferably 120 °C or higher, and preferably 180 °C or lower, more preferably 170 °C or lower. In the finishing kneading step of kneading the vulcanizing agent and the vulcanization accelerator, the kneading temperature is preferably 80 °C or higher, and preferably 120 °C or lower, more preferably 110 °C or lower. Further, the composition kneaded with the vulcanizing agent and the vulcanization accelerator is usually subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is preferably 140 °C or higher, more preferably 150 °C or higher, and preferably 190 °C or lower, more preferably 185 °C or lower.

[0148] The above rubber composition can be applied (as a rubber composition for tires) to, for example, cap treads, sidewalls, base treads, undertreads, clinches, bead apexes, breaker cushion rubbers, carcass cord coating rubbers, insulations, chafers, inner liners, etc., and side reinforcement layers of run-flat tires and other tire members. Among them, from the viewpoint of obtaining more effects, it is desirable that the tire member is an internal tire member. In this specification, the internal tire member refers to a member other than the cap tread that contacts the road surface during driving (such as carcass ply, base tread, breaker, sidewall, clinch apex, bead apex, etc.). In particular, the sidewall and the base tread are preferred.

[0149] The above tire is manufactured by a conventional method using the above rubber composition. That is, a composition blended with various additives as needed is extruded in an unvulcanized state to fit the shape of various tire members such as sidewalls, 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.

[0150] The above tire is not particularly limited, and examples include pneumatic tires, solid tires, airless tires, etc. Among them, pneumatic tires are preferred.

[0151] The above tire is suitably used as a passenger car tire, a large passenger car tire, a large SUV tire, a truck / bus tire, a two-wheeler 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 mine tire, etc.

[0152] The above tire includes a tire member made from the above rubber composition. In the above tire, the content A (parts by mass) of the carbon black with respect to 100 parts by mass of the rubber component of the above rubber composition, the amount B (parts by mass) of nitrogen with respect to 100 parts by mass of the rubber component of the above rubber composition, and the maximum thickness C (mm) of the above tire member satisfy the following formula (1). (1) A × B / C > 0.5 A × B / C is preferably 1.0 or more, more preferably 1.6 or more, still more preferably 2.5 or more, and particularly preferably 3.0 or more. The upper limit of A × B / C is preferably 8.0 or less, more preferably 5.0 or less, and still more preferably 4.0 or less. When within the above range, the effect tends to be obtained more favorably.

[0153] In the above rubber composition, the amount B (content B of nitrogen atoms) of nitrogen with respect to 100 parts by mass of the rubber component is 0.20 parts by mass or more. B is preferably 0.25 parts by mass or more, more preferably 0.28 parts by mass or more, still more preferably 0.30 parts by mass or more. The upper limit of B is preferably 0.50 or less, more preferably 0.40 or less, still more preferably 0.33 or less. When within the above range, the effect tends to be obtained more favorably. In this specification, the amount of nitrogen B relative to 100 parts by mass of the rubber component means the content of nitrogen atoms in the compounds containing nitrogen in the rubber composition relative to 100 parts by mass of the rubber component in the rubber composition. Note that the amount of nitrogen B does not include the amount of nitrogen atoms of the modified rubber modified with a nitrogen-containing modifier and the amount of nitrogen atoms of fillers such as the nitrogen-treated recycled carbon black. That is, for example, in the case of a rubber composition composed of 100 parts by mass of a modified rubber modified with a nitrogen-containing modifier, 10 parts by mass of a general-purpose carbon black, 10 parts by mass of the nitrogen-treated recycled carbon black, 1 part by mass of the nitrogen compound, 2 parts by mass of stearic acid, 2 parts by mass of zinc oxide, 2 parts by mass of sulfur, 1 part by mass of an antioxidant containing nitrogen, and 0.5 part by mass of a vulcanization accelerator containing nitrogen, the amount of nitrogen B relative to 100 parts by mass of the rubber component is the total content of the amount of nitrogen (parts by mass) in the above nitrogen compound, the amount of nitrogen (parts by mass) in the antioxidant containing nitrogen, and the amount of nitrogen (parts by mass) in the vulcanization accelerator containing nitrogen relative to 100 parts by mass of the rubber component.

[0154] In the above tire, the maximum thickness C of the above tire member is preferably 8.0 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. The lower limit of the thickness C of the above tire member is preferably 0.5 mm or more, more preferably 0.8 mm or more, still more preferably 1.0 mm or more, and when within the above range, the effect tends to be obtained suitably.

[0155] In this specification, the maximum thickness C of the tire member means the maximum value of the thickness of each tire member (sidewall, base tread, etc.). The thickness at each point on the surface of each tire member is the linear distance measured along the normal line of the surface of each tire member at that point, and the maximum thickness C of each tire member is the maximum value of the thickness at each point.

[0156] In the above tire, the maximum thickness Ts (mm) of the sidewall is preferably 8.0 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. The lower limit of Ts is preferably 2.0 mm or more, more preferably 2.5 mm or more, and still more preferably 3.0 mm or more. Also, when within the above range, there is a tendency that the effects can be suitably obtained.

[0157] 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 sidewall surface is the linear distance measured along the normal line of the sidewall surface at that point, and the maximum thickness Ts of the sidewall is the maximum value of the thickness at each point.

[0158] In the above tire, it is desirable that the ratio (A / C) of the content A (parts by mass) of the above carbon black to 100 parts by mass of the rubber component of the above rubber composition and the maximum thickness C (mm) of the above tire member exceeds 21.0. A / C is preferably 22.0 or more, more preferably 24.0 or more, and still more preferably 25.0 or more. Also, the lower limit of A / C is preferably 50.0 or less, more preferably 40.0 or less, and still more preferably 35.0 or less. When within the above range, there is a tendency that the effects can be obtained more favorably.

[0159] When A / C exceeds a predetermined value, particularly when it exceeds 21.0, the mechanism by which more effects can be obtained is not clear, but it becomes possible to increase the amount of carbon black in a sufficient amount to enhance the reinforcing property with respect to the thickness of the tire member. Therefore, it is presumed that the comprehensive performance of handling stability, wear resistance, and low fuel consumption is improved.

[0160] In the above tire, it is desirable that the ratio (B / C) of the amount B (parts by mass) of nitrogen to 100 parts by mass of the rubber component of the above rubber composition and the maximum thickness C (mm) of the above tire member is less than 0.15. B / C is preferably 0.14 or less, more preferably 0.13 or less, and still more preferably 0.12 or less. Also, the lower limit of B / C is preferably 0.01 or more, more preferably 0.05 or more, and still more preferably 0.08 or more. When within the above range, the effect tends to be obtained more favorably.

[0161] When B / C is less than a predetermined value, particularly less than 0.15, the mechanism by which a more effective result is obtained is not clear, but the balance between the thickness of the tire member and the amount of nitrogen becomes good. Therefore, it is presumed that the overall performance of handling stability, wear resistance, and low fuel consumption is improved.

[0162] In the above tire, the groove depth D (mm) of the circumferential groove formed in the tread is preferably 5.5 mm or more, more preferably 5.8 mm or more, and still more preferably 6.0 mm or more, and is preferably 8.5 mm or less, more preferably 8.0 mm or less, and still more preferably 7.5 mm or less. When within the above range, the effect tends to be obtained more favorably.

[0163] When the groove depth D of the circumferential groove formed in the tread is adjusted within a predetermined range, the mechanism by which a more effective result is obtained is not clear, but by adjusting the groove depth, weight reduction and elongation maintenance are balanced, and as a result, it is presumed that the overall performance of handling stability, wear resistance, and low fuel consumption is improved.

[0164] In this specification, the groove depth D of the circumferential groove means the distance measured along the normal line of the surface obtained by extending the surface forming the ground contact surface of the outermost surface of the tread, from the surface obtained by extending the surface 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.

[0165] It is desirable that the ratio (A / D) of the content A (parts by mass) of the carbon black to 100 parts by mass of the rubber component to the groove depth D (mm) of the circumferential groove formed in the tread is 3.0 or more and 10.0 or less with respect to 100 parts by mass of the rubber component of the above rubber composition. A / D is preferably 4.5 or more, more preferably 5.0 or more, and still more preferably 5.5 or more. Also, the upper limit of A / D is preferably 9.0 or less, more preferably 8.5 or less, and still more preferably 8.0 or less. When within the above range, the effect tends to be obtained more favorably.

[0166] When A / D is adjusted to a predetermined range, the mechanism by which a more effective result is obtained is not clear. However, by adjusting the groove depth, weight reduction and elongation maintenance are balanced, and by containing a sufficient amount of carbon, the affinity with the polymer is improved, and the reinforcing property and low fuel consumption property can be improved. Therefore, it is presumed that the overall performance of handling stability, wear resistance and low fuel consumption is improved.

[0167] It is desirable that the ratio (B / D) of the amount of nitrogen B (parts by mass) to 100 parts by mass of the rubber component of the rubber composition to the groove depth D (mm) of the circumferential groove formed in the tread of the above tire is 0.03 or more and 0.08 or less. B / D is preferably 0.04 or more, more preferably 0.05 or more. Also, the upper limit of B / D is preferably 0.08 or less, more preferably 0.07 or less, and still more preferably 0.06 or less. When within the above range, the effect tends to be obtained more favorably.

[0168] When B / D is adjusted to a predetermined range, the mechanism by which a more effective result is obtained is not clear. However, by adjusting the groove depth, weight reduction and elongation maintenance are balanced, and by containing a sufficient amount of nitrogen atoms, the affinity with the polymer is improved, and the reinforcing property and low fuel consumption property can be improved. Therefore, it is presumed that the overall performance of handling stability, wear resistance and low fuel consumption is improved.

[0169] In this specification, dimensions such as thickness are measured with the bead portion of the tire adjusted to the regular rim width. At the time of measurement, the tire is cut out in the tire radial direction, and both bead ends of the sample are fixed in a state where they are adjusted to the width of the regular rim.

[0170] In this specification, unless otherwise specified, the dimensions of each part of the tire are values measured in the normal state. The "normal state" refers to a state in which the tire is mounted on a standard rim and filled with the standard internal pressure, and is in a non-loaded state. 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 by 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 hold the internal pressure, that is, the rim that does not cause air leakage between the rim / 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 is 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 by the standard, it refers to the standard internal pressure (however, 250 KPa or more) of another tire size (defined by 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.

[0171] Hereinafter, an example of the above tire will be described with reference to the drawings, but it is not limited to such a form.

[0172] 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 bilaterally symmetric. The tread 4 includes a cap layer 30 (cap tread) and a base layer 28 (base tread).

[0173] Note that in FIG. 1, an example of a two - layer - structure tread 4 composed of a cap layer 30 and a base layer 28 is shown, but a single - layer - structure tread or a tread having a structure of three or more layers may also be used.

[0174] In the tire 2, each sidewall 6 extends substantially radially inward from the end 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.

[0175] In the tire 2 of FIG. 1, the sidewall 6 is composed of the above - mentioned rubber composition. The sidewall 6 is composed of a rubber composition containing a rubber component and carbon black including recycled carbon black, the rubber composition contains a nitrogen compound, the amount of nitrogen relative to 100 parts by mass of the rubber component is 0.20 parts by mass or more, and the content A of carbon black, the amount of nitrogen B, and the maximum thickness Ts (mm) of the sidewall 6 relative to 100 parts by mass of the rubber component satisfy the formula (1) "A×B / C>0.5".

[0176] 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.

[0177] Each clinch 10 is located substantially radially inside the sidewall 6 and has a portion in contact with the rim at at least one location or more.

[0178] The carcass 14 is provided with a carcass ply 36. In this tire 2, the carcass 14 consists of a single carcass ply 36, but it may also be composed of two or more plies.

[0179] In this tire 2, the carcass ply 36 is spanned between the bead cores 32 on both sides and runs along the tread 4 and the sidewall 6. The carcass ply 36 is folded back from the axial inner side to the outer side around each bead core 32. Due to this folding, a main part 36a and a pair of folded parts 36b are formed on the carcass ply 36. That is, the carcass ply 36 is provided with a main part 36a and a pair of folded parts 36b.

[0180] Each bead core 32 is provided with a bead apex 34 that extends radially outward from this bead core 32. The bead core 32 is ring-shaped and preferably includes a wound non-stretchable wire. The bead apex 34 tapers radially outward.

[0181] 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.

[0182] The belt layer 16 in FIG. 1 is located radially inside the tread 4. The belt layer 16 is laminated with the carcass 14. The belt layer 16 reinforces the carcass 14. In the tire 2 of FIG. 1, the belt layer 16 consists of an inner layer 38 and an outer layer 40. As is clear from FIG. 1, in the axial direction, it is desirable that the width of the inner layer 38 is slightly larger than the width of the outer layer 40. In this tire 2, the axial width of the belt layer 16 is preferably not less than 0.6 times and not more than 0.9 times the cross-sectional width of the tire 2.

[0183] Each of the inner layer 38 and the outer layer 40 desirably consists of a large number of parallel single-wire steel cords (steel monofilaments) and topping rubber (coating rubber). In other words, the belt layer 16 includes a large number of parallel steel monofilaments.

[0184] The band 18 in FIG. 1 is located radially outside the belt layer 16. In the axial direction, the band 18 has a width equivalent to the width of the belt layer 16. This band 18 may have a width larger than the width of this belt layer 16.

[0185] Although not shown, the band 18 desirably consists of cords and topping rubber. The cords are wound in a spiral. This band 18 has a so-called jointless structure. The cords extend substantially in the circumferential direction. The angle of the cords with respect to the circumferential direction is preferably 5° or less, and further preferably 2° or less. Since the belt layer 16 is constrained by these cords, the lifting of the belt layer 16 is suppressed.

[0186] The belt layer 16 and the band 18 in FIG. 1 constitute a reinforcing layer. The reinforcing layer may be constituted by only the belt layer 16.

[0187] FIG. 2 is an enlarged view near the tread 4 in FIG. 1. The tire in FIG. 2 is the tire 2 having a groove 26 on the tire equatorial plane (on the CL).

[0188] In FIG. 2, the symbol P is a point on the sidewall surface 46. T is the thickness of the sidewall 6 at the point P. This thickness T is measured along the normal line of the sidewall surface 46 at the point P. The maximum thickness Ts of the sidewall 6 is the maximum dimension among the thicknesses at each point on the sidewall surface 46 of the sidewall 6.

[0189] 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.

[0190] 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 this cloth. This chafer 22 may be integrated with the clinch 10.

[0191] In this tire 2, the tread 4 has main grooves 42 as grooves 26. As shown in FIG. 1, a plurality of, specifically three, main grooves 42 are engraved in this tread 4. These main grooves 42 are arranged at intervals in the axial direction. By engraving three main grooves 42 in this tread 4, four ribs 44 extending in the circumferential direction are formed. That is, the main groove 42 is between the ribs 44.

[0192] 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 sufficiently contact the road surface. D in FIG. 2 indicates the groove depth of the circumferential main groove 42 formed in the tread 4.

[0193] In the tire 2, regarding the carbon black content A per 100 parts by mass of the rubber component of the sidewall 6, the nitrogen amount B per 100 parts by mass of the rubber component of the sidewall 6, the maximum thickness C (mm) of the sidewall 6, and the groove depth D of the circumferential groove formed in the tread, it is desirable that A / C, B / C, A / D, B / D, C, and D are within the aforementioned ranges.

Example

[0194] Examples (embodiments) considered preferable for implementation are shown below, but the scope of the present disclosure is not limited to the embodiments.

[0195] 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 Carbon black: N660 (average primary particle diameter: 66 nm) manufactured by Asahi Carbon Co., Ltd. Recycled carbon black 1: Commercial product (manufactured by Klean Industires, average primary particle diameter: 35 nm) Recycled carbon black 2: Recycled carbon black obtained by dispersing the above recycled carbon black 1 in dehydrated toluene and further reacting it with benzyl isocyanate (nitrogen compound 2) Nitrogen compound 1: The compound shown below (described in JP 2020-70302 A)

Chemical formula

[0196] <Preparation of test tires> According to the compounding contents shown in each table, using a 1.7 L Banbury mixer manufactured by Kobe Steel, Ltd., materials other than sulfur and the vulcanization accelerator are kneaded at 150 °C for 5 minutes to obtain a kneaded product. Sulfur and the 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 laminated together with other tire members on a tire molding machine to form an unvulcanized tire, which is then vulcanized at 170 °C for 10 minutes to produce a test tire (size 205 / 70R15, passenger car tire).

[0197] Assuming test tires obtained from compositions with formulations and specifications changed according to each table, the results calculated based on the following evaluation methods are shown in each table. Note that the reference comparative examples are as follows. Table 1: Comparative Example 1-1 Table 2: Comparative Example 2-1 Table 3: Comparative Example 3-1

[0198] <Handling stability> The test tire is mounted on a vehicle, and the control stability when driving on a test course is subjectively evaluated on a 5-point scale (maximum 5 points). The evaluation is performed by 20 test drivers, and the total value is displayed as an index with the evaluation criterion set to 100. The larger the index, the higher the control stability and the better the handling stability.

[0199] <Wear resistance> The test tire is mounted on a vehicle, and the groove depth of the tread after a driving distance of 8000 km is measured. Then, the driving distance when the groove depth decreases by 1 mm is calculated and displayed as an index according to the following formula. The larger the numerical value, the better the wear resistance. (Wear resistance index) = (Driving distance when the groove depth of each formulation decreases by 1 mm) / (Driving distance when the groove depth of the reference comparative example decreases by 1 mm) × 100

[0200] <Low fuel consumption> Using a rolling resistance tester, the rolling resistance when the test tire is run at an internal pressure of (230 kPa) and a speed of (80 km / h) is measured and displayed as an index with the reference comparative example set to 100. The larger the numerical value, the better the low fuel consumption.

[0201]

Table 1

[0202]

Table 2

[0203]

Table 3

[0204] The tire of the present invention (1) includes a tire member composed of a rubber composition containing a rubber component and carbon black including recycled carbon black, and the rubber composition contains a nitrogen compound, the amount of nitrogen with respect to 100 parts by mass of the rubber component is 0.20 part by mass or more, the content A (parts by mass) of the carbon black, the amount of nitrogen B (parts by mass), and the maximum thickness C (mm) of the tire member with respect to 100 parts by mass of the rubber component satisfy the following formula (1). (1) A × B / C > 0.5

[0205] The tire of the present invention (2) is the tire according to the present invention (1), wherein the content A (parts by mass) of the carbon black with respect to 100 parts by mass of the rubber component is 30 parts by mass or more.

[0206] The tire of the present invention (3) is the tire according to the present invention (1) or (2), wherein the nitrogen compound contains an isocyanate compound.

[0207] The tire of the present invention (4) is a tire in any combination with any one of the present inventions (1) to (3), wherein the average primary particle diameter of the carbon black is 30 nm or more and 60 nm or less.

[0208] The tire of the present invention (5) is a tire in any combination with any one of the present inventions (1) to (4), wherein the recycled carbon black and the nitrogen compound are those obtained by previously surface-treating the recycled carbon black with the nitrogen compound.

[0209] The tire of the present invention (6) is a tire in any combination of the present inventions (1) to (5) in which the ratio (A / C) of the content A (parts by mass) of the carbon black to 100 parts by mass of the rubber component and the maximum thickness C (mm) of the tire member exceeds 21.0.

[0210] The tire of the present invention (7) is a tire in any combination of the present inventions (1) to (6) in which the ratio (B / C) of the nitrogen amount B (parts by mass) to 100 parts by mass of the rubber component and the maximum thickness C (mm) of the tire member is less than 0.15.

[0211] The tire of the present invention (8) is a tire in any combination of the present inventions (1) to (7) in which the groove depth D of the circumferential groove formed in the tread is 5.5 mm or more and 8.5 mm or less.

[0212] The tire of the present invention (9) is the tire according to the present invention (8), in which the ratio (A / D) of the content A (parts by mass) of the carbon black to 100 parts by mass of the rubber component and the groove depth D (mm) of the circumferential groove formed in the tread is 3.0 or more and 9.0 or less.

[0213] The tire of the present invention (10) is the tire according to the present invention (8) or (9), in which the ratio (B / D) of the nitrogen amount B (parts by mass) to 100 parts by mass of the rubber component and the groove depth D (mm) of the circumferential groove formed in the tread is 0.04 or more and 0.08 or less.

Explanation of Signs

[0214] 2 Tire 4 Tread 6 Sidewall 8 Wing 10 Clincher 12 Bead 14 Carcass 16 Belt layer 18 Band 20 Inner liner 22 Chafer 26 Groove 28 Base layer 30 Cap layer 32 Bead core 34 Bead apex 36 Carcass ply 36a Main part 36b Folded-back part 38 Inner layer 40 Outer layer 42 Main groove 44 Rib 46 Sidewall surface CL Equatorial plane of the tire T Thickness of the sidewall D Depth of the main groove of the circumferential main groove formed in the tread

Claims

1. A tire comprising a tire member composed of a rubber composition containing a rubber component and carbon black including recycled carbon black, wherein the rubber composition contains a nitrogen compound, the amount of nitrogen relative to 100 parts by mass of the rubber component is 0.20 parts by mass or more, and a tire in which the content A (parts by mass) of the carbon black, the amount of nitrogen B (parts by mass), and the maximum thickness C (mm) of the tire member relative to 100 parts by mass of the rubber component satisfy the following formula (1). (1) A × B / C > 0.5

2. The tire according to claim 1, wherein the content A (parts by mass) of the carbon black relative to 100 parts by mass of the rubber component is 30 parts by mass or more.

3. The tire according to claim 1, wherein the nitrogen compound contains an isocyanate compound.

4. The tire according to claim 1, wherein the average primary particle diameter of the carbon black is 30 nm or more and 60 nm or less.

5. The tire according to claim 1, wherein the recycled carbon black and the nitrogen compound are those obtained by previously surface-treating the recycled carbon black with the nitrogen compound.

6. The tire according to claim 1, wherein the ratio (A / C) of the content A (parts by mass) of the carbon black to the maximum thickness C (mm) of the tire member relative to 100 parts by mass of the rubber component exceeds 21.

0.

7. The tire according to claim 1, wherein the ratio (B / C) of the amount of nitrogen B (parts by mass) to the maximum thickness C (mm) of the tire member relative to 100 parts by mass of the rubber component is less than 0.

15.

8. The tire according to claim 1, wherein the groove depth D of the circumferential groove formed in the tread is 5.5 mm or more and 8.5 mm or less.

9. The tire according to claim 8, wherein the ratio (A / D) of the content A (parts by mass) of the carbon black to 100 parts by mass of the rubber component and the groove depth D (mm) of the circumferential groove formed in the tread is 3.0 or more and 9.0 or less.

10. The tire according to claim 8, wherein the ratio (B / D) of the nitrogen amount B (parts by mass) to 100 parts by mass of the rubber component and the groove depth D (mm) of the circumferential groove formed in the tread is 0.04 or more and 0.08 or less.

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