Rubber composition for tires and tires

Abstract

To provide a rubber composition that enables overall improvement in rubber strength and grip performance, and provide a tire.SOLUTION: A tire rubber composition comprises a rubber component, microfibrillated vegetable fibers, and at least one selected from the group consisting of fat, biomass-derived wax, and lower fatty acid esters with 12 or less carbon atoms.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to rubber compositions for tires and tires using the same. [Background technology]

[0002] Techniques have been proposed for compounding fillers such as carbon black and silica to reinforce rubber compositions and improve physical properties such as modulus (complex modulus of elasticity), and various filler dispersion techniques have been disclosed, such as a method for producing a specific silica-natural rubber composite (see Patent Document 1, etc.). However, further improvements in rubber strength, grip performance, etc. are desired. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-107211 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure aims to solve the above problems and provide a rubber composition and a tire that improve the overall performance of rubber strength and grip performance. [Means for solving the problem]

[0005] The present disclosure relates to a rubber composition for tires, which comprises a rubber component, microfibrillated plant fibers, and at least one selected from the group consisting of fat, biomass-derived wax, and lower fatty acid esters having 12 or less carbon atoms. [Effects of the Invention]

[0006] The present disclosure provides a rubber composition for tires that includes a rubber component, microfibrillated plant fibers, and at least one selected from the group consisting of fats, biomass-derived waxes, and lower fatty acid esters having 12 or less carbon atoms, thereby improving the overall performance of rubber strength and grip performance. DETAILED DESCRIPTION OF THE INVENTION

[0007] <Rubber composition> The present disclosure relates to a rubber composition for tires, which comprises a rubber component, microfibrillated plant fibers, and at least one selected from the group consisting of fats, biomass-derived waxes, and lower fatty acid esters having 12 or less carbon atoms.

[0008] The reason why the above-mentioned effects can be obtained with the above rubber composition is presumed to be as follows. It is believed that in the rubber composition, at least one selected from the group consisting of fats, biomass-derived waxes, and lower fatty acid esters having 12 or less carbon atoms reacts with the hydroxyl groups and carbonyl groups of the microfibrillated plant fibers, improving the reinforcement properties. Therefore, it is presumed that the overall performance of rubber strength and grip performance is improved.

[0009] (rubber component) The rubber composition includes a rubber component. In the rubber composition, the rubber component is a component that contributes to crosslinking, and is generally a polymer having a weight average molecular weight (Mw) of 10,000 or more.

[0010] The weight average molecular weight of the rubber component is preferably 50,000 or more, more preferably 150,000 or more, and even more preferably 200,000 or more, and is preferably 2,000,000 or less, more preferably 1,500,000 or less, and even more preferably 1,000,000 or less. Within the above ranges, the effect tends to be more favorably obtained.

[0011] In this specification, the weight average molecular weight (Mw) can be determined in terms of standard polystyrene based on measurements obtained using a gel permeation chromatograph (GPC) (GPC-8000 series, manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M, manufactured by Tosoh Corporation).

[0012] The rubber component is not particularly limited, and any rubber known in the tire field can be used. Examples include diene rubbers such as isoprene rubber, butadiene rubber (BR), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), and styrene-isoprene-butadiene copolymer rubber (SIBR). These may be used alone or in combination of two or more. Among these, isoprene rubber, BR, and SBR are preferred from the viewpoint of obtaining better effects.

[0013] Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. NRs such as SIR20, RSS#3, and TSR20 are commonly used in the tire industry. IRs are not particularly limited, and examples of IRs such as IR2200 are commonly used in the tire industry. Modified NRs include deproteinized natural rubber (DPNR) and highly purified natural rubber (UPNR). Modified NRs include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Modified IRs include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used alone or in combination of two or more. NR is preferred.

[0014] When the rubber composition contains an isoprene-based rubber, the content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 50% by mass or more, even more preferably 70% by mass or more, particularly preferably 80% by mass or more, and may be 100% by mass. When the content is within the above range, better effects tend to be obtained.

[0015] The BR is not particularly limited, and examples thereof include BRs with a high cis content such as BR1220 manufactured by Zeon Corporation, BR150B manufactured by Ube Industries, Ltd., and BR1280 manufactured by LG Chem, BRs containing 1,2-syndiotactic polybutadiene crystals (SPB) such as VCR412 and VCR617 manufactured by Ube Industries, Ltd., and butadiene rubbers synthesized using a rare earth catalyst (rare earth BR), which are commonly used in the tire industry. These may be used alone or in combination of two or more.

[0016] The cis amount (cis content) of the BR is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more, and is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97% by mass or less. Within the above ranges, the effect tends to be more favorably obtained. The cis content of BR can be measured by infrared absorption spectroscopy.

[0017] When the rubber composition contains BR, the BR content, relative to 100% by mass of the rubber component, is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and particularly preferably 20% by mass or more, and is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 35% by mass or less, and particularly preferably 30% by mass or less. Within the above ranges, the effects tend to be more favorably obtained.

[0018] The SBR is not particularly limited, and examples thereof include emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), etc. Commercially available products include those from Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, and Zeon Corporation.

[0019] The styrene content of SBR is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and particularly preferably 20% by mass or more. The styrene content is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. Within the above range, the effect tends to be more favorable. In this specification, the styrene content of SBR is 1 It is calculated by H-NMR measurement.

[0020] The vinyl content of the SBR is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more. The vinyl content is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less. Within the above range, the effect tends to be more favorable. In this specification, the vinyl content (amount of 1,2-bonded butadiene units) of SBR can be measured by infrared absorption spectroscopy.

[0021] When the 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 50% by mass or more, even more preferably 60% by mass or more, particularly preferably 70% by mass or more, and is preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 85% by mass or less, particularly preferably 80% by mass or less. When the content is within the above range, better effects tend to be obtained.

[0022] When the rubber composition contains SBR and BR, the total content of SBR and BR in 100% by mass of the rubber component is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, and may be 100% by mass. When it is within the above range, the effect tends to be more favorably obtained.

[0023] The rubber component may be oil-extended rubber. These may be used alone or in combination of two or more. Examples of oils used in oil-extended rubber include those described below. The amount of oil in the oil-extended rubber is not particularly limited, but is usually about 10 to 50 parts by mass per 100 parts by mass of rubber solids.

[0024] The rubber component may be modified to introduce a functional group that interacts with a filler such as silica. Examples of the functional group include a silicon-containing group (-SiR3 (R may be the same or different and is hydrogen, a hydroxyl group, a hydrocarbon group, an alkoxy group, or the like), an amino group, an amido 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 imido 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, or the like. These functional groups may have a substituent. Of these, a silicon-containing group is preferred, and -SiR3 (R may be the same or different and is hydrogen, a hydroxyl group, a hydrocarbon group (preferably a hydrocarbon group having 1 to 6 carbon atoms (more preferably an alkyl group having 1 to 6 carbon atoms)), or an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms)), and at least one R is a hydroxyl group) is more preferred.

[0025] Specific examples of compounds (modifiers) that introduce the above-mentioned functional groups include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane.

[0026] (filler) The rubber composition contains microfibrillated plant fibers as a filler.

[0027] In the rubber composition, the content of the microfibrillated plant fibers is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 3 parts by mass or more, and particularly preferably 4 parts by mass or more, per 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, even more preferably 20 parts by mass or less, and particularly preferably 10 parts by mass or less. Within the above range, better effects tend to be obtained.

[0028] As the microfibrillated plant fiber, cellulose microfibrils are preferred from the viewpoints of breaking strength, abrasion resistance, etc. Cellulose microfibrils are not particularly limited as long as they are derived from natural products, and examples include those derived from resource biomass such as fruits, grains, and root vegetables, wood, bamboo, hemp, jute, and kenaf, as well as pulp, paper, and cloth obtained from these as raw materials, waste biomass such as agricultural waste, food waste, and sewage sludge, unused biomass such as rice straw, wheat straw, and thinned wood, as well as cellulose produced by sea squirts, acetic acid bacteria, etc. These microfibrillated plant fibers may be used alone or in combination of two or more.

[0029] In this specification, cellulose microfibrils typically refer to cellulose fibers having an average fiber diameter of several tens of μm (e.g., 20 to 30 μm or less), preferably 10 μm or less, and more typically refer to cellulose fibers having a microstructure formed by the aggregation of cellulose molecules with an average fiber diameter of 500 nm or less (microfibrillated plant fibers having an average fiber diameter of several tens of μm or less, 10 μm or less, or 500 nm or less).Typical cellulose microfibrils can be formed, for example, as an aggregate of cellulose fibers having the above-mentioned average fiber diameter.

[0030] The method for producing microfibrillated plant fibers is not particularly limited, but examples include a method in which a raw cellulose microfibril material is chemically treated with an alkali such as sodium hydroxide as necessary, and then mechanically ground or beaten using a refiner, twin-screw kneader (twin-screw extruder), twin-screw kneader / extruder, high-pressure homogenizer, media stirring mill, millstone, grinder, vibrating mill, sand grinder, or the like. These methods separate lignin from the raw material by chemical treatment, thereby obtaining microfibrillated plant fibers that are substantially free of lignin. Another example is a method in which the raw cellulose microfibril material is subjected to ultra-high pressure treatment.

[0031] As the microfibrillated plant fibers, for example, products manufactured by Sugino Machine Ltd., Daicel FineChem Ltd., etc. can be used.

[0032] As described above, unmodified microfibrillated plant fibers obtained by the above-mentioned production methods can be sufficiently oriented in a polymer. However, in addition to unmodified microfibrillated plant fibers, it is also possible to use microfibrillated plant fibers that have been subjected to oxidation treatment or various chemical modification treatments, or microfibrillated plant fibers that have been subjected to oxidation treatment or various chemical modification treatments using natural products that can be used to produce cellulose microfibrils (e.g., wood, pulp, bamboo, hemp, jute, kenaf, agricultural waste, cloth, paper, sea squirt cellulose, etc.) as cellulose raw materials, followed by defibration treatment as necessary (e.g., chemically modified microfibrillated plant fibers).

[0033] Examples of chemical modifications of microfibrillated plant fibers include esterification, etherification, acetalization, etc. Specific examples include acylation such as acetylation, cyanoethylation, amination, sulfone esterification, phosphate esterification, alkyl esterification, alkyl etherification, complex esterification, β-keto esterification, alkylation such as butylation, chlorination, etc. Further examples include alkyl carbamate and aryl carbamate.

[0034] The chemically modified microfibrillated plant fibers are preferably chemically modified to have a degree of substitution in the range of 0.2 to 2.5. Here, the degree of substitution refers to the average number of hydroxyl groups per glucose ring unit of cellulose that have been chemically modified and substituted with other functional groups, with a theoretical maximum value of 3. The degree of substitution is more preferably in the range of 0.3 to 2.5, even more preferably in the range of 0.5 to 2.3, and particularly preferably in the range of 0.5 to 2.0. When the chemically modified microfibrillated plant fibers are a combination of two or more types of fibers, the degree of substitution is calculated as the average for the entire chemically modified microfibrillated plant fiber.

[0035] The degree of substitution in chemically modified microfibrillated plant fibers can be confirmed, for example, by titration using 0.5N-NaOH and 0.2N-HCl, or by measurement such as NMR or infrared absorption spectroscopy.

[0036] Suitable chemically modified microfibrillated plant fibers include aminated microfibrillated plant fibers with a degree of substitution in the range of 0.3 to 2.5, preferably 0.3 to 2.3, more preferably 0.5 to 2.3, even more preferably 0.7 to 2.0, and particularly preferably 0.9 to 1.8.

[0037] When the chemically modified microfibrillated plant fiber is an acetylated microfibrillated plant fiber, the degree of substitution is preferably within the range of 0.3 to 2.5; when it is a sulfone-esterified microfibrillated plant fiber, the degree of substitution is preferably within the range of 0.3 to 1.8; when it is an alkyl-esterified microfibril cellulose, the degree of substitution is preferably within the range of 0.3 to 1.8; when it is a complex-esterified microfibril cellulose, the degree of substitution is preferably within the range of 0.4 to 1.8; when it is a β-keto-esterified microfibril cellulose, the degree of substitution is preferably within the range of 0.3 to 1.8; when it is an alkyl-carbamated microfibril cellulose, the degree of substitution is preferably within the range of 0.3 to 1.8; and when it is an aryl-carbamated microfibril cellulose, the degree of substitution is preferably within the range of 0.3 to 1.8.

[0038] Acetylation can be carried out, for example, by adding acetic acid, concentrated sulfuric acid, or acetic anhydride to the microfibrillated plant fiber to cause a reaction. Specifically, the acetylation can be carried out by a conventionally known method, such as by reacting the microfibrillated plant fiber with acetic anhydride in a mixed solvent of acetic acid and toluene in the presence of a sulfuric acid catalyst to cause the acetylation reaction to proceed, and then replacing the solvent with water.

[0039] The amination can be carried out by, for example, a method in which an oxidation treatment using an N-oxyl compound such as 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) is performed, followed by a reaction with an amine compound (for example, a primary amine compound having 1 to 30 carbon atoms such as oleylamine (preferably a primary amine compound having 3 to 25 carbon atoms having a saturated or unsaturated bond, more preferably a primary amine compound having 6 to 23 carbon atoms having an unsaturated bond, and even more preferably a primary amine compound having 10 to 20 carbon atoms having an unsaturated double bond)) or a quaternary alkylammonium salt (preferably a quaternary alkylammonium salt having 1 to 30 carbon atoms, more preferably a quaternary alkylammonium halide having 1 to 20 carbon atoms such as hexadecyltrimethylammonium chloride) in an alcohol (for example, an alcohol having 1 to 10 carbon atoms such as ethanol (preferably an alcohol having 1 to 5 carbon atoms, more preferably a primary alcohol having 1 to 4 carbon atoms)) to cause a nucleophilic substitution reaction, or by a known method such as tosyl esterification.

[0040] Sulfonation can be carried out by a simple procedure, for example, by dissolving the microfibrillated plant fibers in sulfuric acid and then adding the resulting solution to water. Other methods include treatment with anhydrous sulfuric acid gas, or treatment with chlorosulfonic acid and pyridine.

[0041] Phosphate esterification can be carried out, for example, by treating microfibrillated plant fibers that have been treated with dimethylamine or the like with phosphoric acid and urea.

[0042] Alkyl esterification can be carried out, for example, by the Schotten-Baumann method, in which microfibrillated plant fibers are reacted with a carboxylic acid chloride under basic conditions, while alkyl etherification can be carried out by the Williamson method, in which microfibrillated plant fibers are reacted with an alkyl halide under basic conditions.

[0043] Chlorination can be carried out, for example, by adding thionyl chloride to DMF (dimethylformamide) and heating.

[0044] Complex esterification can be carried out, for example, by reacting microfibrillated plant fibers with two or more types of carboxylic acid anhydrides or carboxylic acid chlorides under basic conditions.

[0045] β-Ketoesterification can be carried out, for example, by reacting microfibrillated plant fibers with diketene or alkylketene dimer, or by transesterification of microfibrillated plant fibers with a β-ketoester compound such as alkylacetoacetate.

[0046] The alkylcarbamation can be carried out, for example, by reacting the microfibrillated plant fibers with an alkyl isocyanate in the presence of a basic catalyst or a tin catalyst.

[0047] The aryl carbamation can be carried out, for example, by reacting the microfibrillated plant fiber with an aryl isocyanate in the presence of a basic catalyst or a tin catalyst.

[0048] The rubber composition may contain fillers other than the microfibrillated plant fibers. The other fillers (filling materials) are not particularly limited, and materials known in the rubber field can be used, including, for example, inorganic fillers such as silica, carbon black, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, mica, etc. Among these, carbon black and silica are preferred from the viewpoint of obtaining better effects.

[0049] Carbon black that can be used in the rubber composition is not particularly limited, but examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available products that can be used include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin-Nichika Carbon Co., Ltd., Columbia Carbon Co., Ltd., and the like. These may be used alone or in combination of two or more types.

[0050] The nitrogen adsorption specific surface area (N2SA) of carbon black is 30m 2 / g or more is preferable, and 50m 2 / g or more is more preferable, and 70m 2 / g or more is more preferable. 2 / g or less is preferable, and 150m 2 / g or less is more preferable, and 130m 2 / g or less is more preferable, and 120m 2 Within the above range, the effect tends to be better.

[0051] In the rubber composition, the carbon black content is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 20 parts by mass or more, and particularly preferably 30 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the content is preferably 150 parts by mass or less, more preferably 100 parts by mass or less, even more preferably 80 parts by mass or less, and particularly preferably 60 parts by mass or less. Within the above range, the effect tends to be more favorably obtained.

[0052] Usable silica includes dry-process silica (anhydrous silica) and wet-process silica (hydrated silica). Among these, wet-process silica is preferred because it has a large number of silanol groups. Commercially available products include those from Degussa, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan, and Tokuyama Corporation. These may be used alone or in combination of two or more.

[0053] The nitrogen adsorption specific surface area (N2SA) of the silica is preferably 50 m 2 / g or more, more preferably 100m 2 / g or more, more preferably 150m 2 / g or more, particularly preferably 170m 2 The upper limit of the N2SA of silica is not particularly limited, but is preferably 350 m 2 / g or less, more preferably 300m 2 / g or less, more preferably 250m 2 Within the above range, there is a tendency for the effect to be better obtained. The N2SA of silica is a value measured by the BET method in accordance with ASTM D3037-93.

[0054] In the rubber composition, the content of silica is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 20 parts by mass or more, and particularly preferably 30 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the content is preferably 150 parts by mass or less, more preferably 100 parts by mass or less, even more preferably 80 parts by mass or less, and particularly preferably 60 parts by mass or less. Within the above range, the effect tends to be more favorably obtained.

[0055] When the rubber composition contains silica, it is preferable that the rubber composition further contains 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, Examples include sulfide-based compounds such as N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based compounds such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and NXT and NXT-Z manufactured by Momentive; vinyl-based compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based compounds such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Commercially available products include those from Degussa, Momentive, Shin-Etsu Silicones Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., and Dow Corning Toray Co., Ltd. These may be used alone or in combination of two or more.

[0056] In the rubber composition, the content of the silane coupling agent is preferably 0.1 parts by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more, relative to 100 parts by mass of silica. The upper limit of the content is preferably 50 parts by mass, more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less. By keeping the content within the above range, handling stability during high-speed driving tends to be improved.

[0057] In the rubber composition, the content of the filler (total amount of fillers such as microfibrillated plant fibers, carbon black, and silica) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 20 parts by mass or more, and particularly preferably 30 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the content is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, even more preferably 100 parts by mass or less, and particularly preferably 80 parts by mass or less. Within the above range, better effects tend to be obtained.

[0058] (Fats, biomass-derived waxes, lower fatty acid esters with 12 or fewer carbon atoms) In the present disclosure, "fat" refers to fat that is solid at room temperature (25°C). "Fat" may be a biomass-derived material or a non-biomass-derived material. "Fat" may be used alone or in combination of two or more types.

[0059] In the present disclosure, the "biomass-derived wax" refers to a biomass-derived wax that is liquid at room temperature (25°C) or a biomass-derived wax that is solid at room temperature (25°C), and any wax derived from biomass can be used. The "biomass-derived wax" may be used alone or in combination of two or more types.

[0060] In the rubber composition, the total content of the fat, biomass-derived wax, and lower fatty acid ester having 12 or less carbon atoms is preferably 100 parts by mass or more, more preferably 300 parts by mass or more, even more preferably 400 parts by mass or more, and particularly preferably 500 parts by mass or more, per 100 parts by mass of the microfibrillated plant fibers. The upper limit of the content is preferably 1000 parts by mass or less, more preferably 900 parts by mass or less, even more preferably 800 parts by mass or less, and particularly preferably 700 parts by mass or less. Within the above range, better effects tend to be obtained. When the rubber composition contains the fat and biomass-derived wax in the above-mentioned amounts, the reaction between the fat or biomass-derived wax and the hydroxyl groups and carbonyl groups of the microfibrillated plant fibers proceeds more rapidly in the rubber composition, resulting in improved reinforcement, and it is presumed that the overall performance of the rubber, including the strength and grip performance, is significantly improved.

[0061] In the rubber composition, the total content of the fat, biomass-derived wax, and lower fatty acid ester having 12 or less carbon atoms is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the content is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 8 parts by mass or less. Within the above range, better effects tend to be obtained.

[0062] Examples of the fat (fats in a solid state at room temperature) include fats (lipids) having a melting point of 25°C or higher. Specific examples of such fats include milk fat, cocoa butter, palm fat, illipe butter, shea butter, kokum butter, sal fat, coconut fat, palm kernel oil, and fractions thereof. Such fats may be cocoa butter or milk fat. Among these, shea butter and palm kernel oil are preferred from the viewpoint of obtaining better effects.

[0063] In the rubber composition, the content of the fat (total amount of fat in a solid state at room temperature) is preferably 100 parts by mass or more, more preferably 300 parts by mass or more, even more preferably 400 parts by mass or more, and particularly preferably 500 parts by mass or more, per 100 parts by mass of the microfibrillated plant fibers. The upper limit of the content is preferably 1000 parts by mass or less, more preferably 900 parts by mass or less, even more preferably 800 parts by mass or less, and particularly preferably 700 parts by mass or less. Within the above ranges, better effects tend to be obtained. The content of shea butter is also preferably within a similar range.

[0064] In addition, in the rubber composition, the content of the fat (total amount of fat in a solid state at room temperature) is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the content is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 8 parts by mass or less. Within the above range, better effects tend to be obtained. The content of shea butter is also preferably within a similar range.

[0065] The biomass-derived wax is not particularly limited as long as it is produced by refining the raw biomass without chemical synthesis. For example, plant-based waxes such as carnauba wax, candelilla wax, rice wax, Japan wax, and jojoba wax (jojoba oil) can be used; and animal-based waxes such as beeswax, lanolin, and spermaceti can be used. Among these, beeswax and jojoba wax (jojoba oil) are preferred from the viewpoint of obtaining better effects.

[0066] In the rubber composition, the content of the biomass-derived wax is preferably 100 parts by mass or more, more preferably 300 parts by mass or more, even more preferably 400 parts by mass or more, and particularly preferably 500 parts by mass or more, per 100 parts by mass of the microfibrillated plant fibers. The upper limit of the content is preferably 1000 parts by mass or less, more preferably 900 parts by mass or less, even more preferably 800 parts by mass or less, and particularly preferably 700 parts by mass or less. Within the above ranges, better effects tend to be obtained. Note that the content of beeswax and the content of jojoba wax (jojoba oil) are also desirably in the same ranges.

[0067] In addition, the content of the biomass-derived wax in the rubber composition is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the content is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 8 parts by mass or less. Within the above ranges, better effects tend to be obtained. The contents of beeswax and jojoba wax (jojoba oil) are also preferably within the same ranges.

[0068] In the lower fatty acid ester having 12 or less carbon atoms, the number of carbon atoms is preferably 6 or more, more preferably 7 or more, and even more preferably 8 or more, and is preferably 11 or less, more preferably 10 or less, and even more preferably 9 or less.

[0069] The lower fatty acid esters include acetates, propionates, butyrates, valerates, caproates, enanthates, caprates, octynecarboxylates, 2-pentyloxyglycolates, ketoates, benzoates, phenylacetates, salicylates, and the like, each having 6 to 12 carbon atoms. Specific examples include ethyl acetoacetate ethylene glycol ketal, allyl amyl glycolate, methyl benzoate, ethyl benzoate, ethyl isovalerate, and isobutyrate. Examples thereof include benzyl, isoamyl acetate, ethyl octanoate, methyl octynecarboxylate, cis-3-hexenyl acetate, o-tert-butylcyclohexyl acetate, bornyl acetate, lavandulyl acetate, styrallyl acetate, phenylethyl acetate, hexyl acetate, benzyl acetate, linalyl acetate, ethyl salicylate, methyl salicylate, ethyl phenylacetate, methyl phenylacetate, isoamyl propionate, benzyl propionate, ethyl hexanoate, ethyl heptanoate, allyl heptanoate, butyl butyrate, hexyl butyrate, etc. Among these, from the viewpoint of obtaining better effects, methyl salicylate (carbon number 8) is preferred, and methyl salicylate is more preferred.

[0070] In the rubber composition, the content of the lower fatty acid ester having 12 or less carbon atoms is preferably 100 parts by mass or more, more preferably 300 parts by mass or more, even more preferably 400 parts by mass or more, and particularly preferably 500 parts by mass or more, per 100 parts by mass of the microfibrillated plant fibers. The upper limit of the content is preferably 1000 parts by mass or less, more preferably 900 parts by mass or less, even more preferably 800 parts by mass or less, and particularly preferably 700 parts by mass or less. Within the above range, better effects tend to be obtained. The content of shea butter is also preferably within a similar range.

[0071] In addition, in the rubber composition, the content of the lower fatty acid ester having 12 or less carbon atoms is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the content is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 8 parts by mass or less. Within the above range, better effects tend to be obtained. The content of shea butter is also preferably within the same range.

[0072] (plasticizer) The rubber composition may contain a plasticizer capable of imparting plasticity to the rubber component. Examples of the plasticizer include liquid plasticizers (plasticizers that are liquid (liquid) at 25°C) and solid plasticizers (plasticizers that are solid at 25°C). The plasticizers may be used alone or in combination of two or more. In the present disclosure, the fats and the biomass-derived waxes are not included in the plasticizer.

[0073] The liquid plasticizer is not particularly limited, and examples thereof include oil, liquid resin, liquid diene polymer, etc. Among them, oil is preferred from the viewpoint of obtaining a more effective effect.

[0074] The oil is not particularly limited, and examples thereof include known oils such as process oil, vegetable oil, or a mixture thereof. Examples of process oils that can be used include paraffin-based process oil (mineral oil), aromatic process oil, naphthenic process oil, and low-PCA (polycyclic aromatic) process oils such as TDAE and MES. Examples of vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil (canola oil), soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice bran oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, macadamia nut oil, and tung oil. These oils may be used alone or in combination of two or more. Among these, vegetable oils and process oils are preferred, and vegetable oils and paraffin-based process oils (mineral oils) are more preferred, from the viewpoint of obtaining better effects.

[0075] In the rubber composition, the content of the liquid plasticizer is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 13 parts by mass or more, and particularly preferably 15 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less.

[0076] Examples of solid plasticizers include aromatic vinyl polymers that are solid at room temperature (25°C), coumarone-indene resins, coumarone resins, indene resins, phenolic resins, rosin resins, petroleum resins, terpene resins, and acrylic resins. The resins may be hydrogenated. These may be used alone or in combination of two or more.

[0077] In the rubber composition, the content of the solid plasticizer is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 13 parts by mass or more, and particularly preferably 15 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less.

[0078] (Other ingredients) The rubber composition may contain an antioxidant. Examples of the antioxidant include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, and N,N'-di-2-naphthyl-p-phenylenediamine. Examples of antioxidants include p-phenylenediamine antioxidants such as quinolone; quinoline antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol-based antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Commercially available products include those from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., and Flexis. These antioxidants may be used alone or in combination of two or more.

[0079] In the rubber composition, the content of the antioxidant is preferably 0.5 parts by mass or more, more preferably 0.8 parts by mass or more, and even more preferably 1.0 part by mass or more, and is preferably 10.0 parts by mass or less, more preferably 6.0 parts by mass or less, and even more preferably 4.0 parts by mass or less, per 100 parts by mass of the rubber component. Within the above ranges, the effect tends to be more favorable.

[0080] The rubber composition may contain a wax other than the biomass-derived wax. The wax is not particularly limited, and examples thereof include petroleum waxes such as paraffin wax and microcrystalline wax; and synthetic waxes such as polymers of ethylene, propylene, etc. Commercially available products that can be used include those from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Seiko Chemical Co., Ltd., etc. These may be used alone or in combination of two or more.

[0081] In the rubber composition, the content of the wax other than the biomass-derived wax is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 6 parts by mass or less, per 100 parts by mass of the rubber component. When the content is within the above range, better effects tend to be obtained.

[0082] The rubber composition may contain stearic acid. As the stearic acid, conventionally known ones can be used, and commercially available products that can be used include products from NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc. These may be used alone or in combination of two or more.

[0083] In the rubber composition, the content of stearic acid is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 10.0 parts by mass or less, and more preferably 6.0 parts by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0084] The rubber composition may contain zinc oxide. As the zinc oxide, conventionally known ones can be used, and commercially available products include those available from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. These may be used alone or in combination of two or more.

[0085] In the rubber composition, the content of zinc oxide is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 10.0 parts by mass or less, and more preferably 6.0 parts by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0086] The rubber composition may contain sulfur. Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur, which are commonly used as crosslinking agents in the rubber industry. Commercially available products include those from Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanzuri Kogyo Co., Ltd., and Hosoi Chemical Industry Co., Ltd. These may be used alone or in combination of two or more.

[0087] In the rubber composition, the sulfur content is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 1.5 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 3.5 parts by mass or less, more preferably 2.8 parts by mass or less, and even more preferably 2.5 parts by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0088] The rubber composition may contain a vulcanization accelerator. Examples of vulcanization accelerators include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole and di-2-benzothiazolyl disulfide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD) and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazyl sulfenamide (CBS), N-tert-butyl-2-benzothiazolyl sulfenamide (TBBS), N-oxyethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, di-orthotolylguanidine, and orthotolylbiguanidine. Commercially available products include those from Sumitomo Chemical Co., Ltd. and Ouchi Shinko Chemical Industry Co., Ltd. These may be used alone or in combination.

[0089] In the rubber composition, the content of the vulcanization accelerator is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 4 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 7 parts by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0090] In addition to the above components, the rubber composition may further contain additives commonly used in the tire industry, such as organic peroxides, etc. The content of these additives is preferably 0.1 to 200 parts by mass per 100 parts by mass of the rubber component.

[0091] The rubber composition can be produced, for example, by kneading the above-mentioned components using a rubber kneading device such as an open roll or a Banbury mixer, followed by vulcanization.

[0092] As for kneading conditions, in the base kneading step in which additives other than the vulcanizing agent and vulcanization accelerator are kneaded, the kneading temperature is usually 100 to 180°C, preferably 120 to 170°C. In the finish kneading step in which the vulcanizing agent and vulcanization accelerator are kneaded, the kneading temperature is usually 120°C or lower, preferably 85 to 110°C. Furthermore, the composition kneaded with the vulcanizing agent and vulcanization accelerator is usually subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 140 to 190°C, preferably 150 to 185°C. The vulcanization time is usually 5 to 15 minutes.

[0093] In particular, when the rubber composition contains at least one selected from the group consisting of the vegetable oil and the process oil, it is desirable to produce the rubber composition by a production method including step 1 of mixing the ester compound and at least one selected from the group consisting of the vegetable oil and the process oil, step 2 of mixing the mixture 1 produced in step 1 in a molten state with the microfibrillated plant fibers, and step 3 of mixing the mixture 2 produced in step 2 with the rubber component. This can improve the overall performance of the rubber composition, including rubber strength and grip performance.

[0094] The mixing steps 1 to 3 can be carried out by a known method, for example, by using a rubber kneading device such as an open roll or a Banbury mixer.

[0095] In step 2, the molten mixture 1 can be prepared by appropriately adjusting the temperature, and can be made molten by adjusting the temperature, for example, preferably to 50° C. or higher, more preferably to 60° C. or higher, and even more preferably to 70° C. or higher. The upper limit of the temperature is not particularly limited, and may be adjusted to, for example, 100° C. or lower.

[0096] In order to obtain a better effect in step 2, it is desirable to mix the microfibrillated plant fibers in the form of an aqueous solution (aqueous solution of microfibrillated plant fibers) dispersed in water with the molten mixture 1.

[0097] The aqueous solution of microfibrillated plant fibers can be produced by known methods, for example, by dispersing microfibrillated plant fibers in water using a homogenizer (such as a high-speed homogenizer or an ultrasonic homogenizer), a colloid mill, a blender mill, etc. The temperature and time during preparation can also be appropriately set so that the microfibrillated plant fibers are sufficiently dispersed in water.

[0098] The content (solid content) of microfibrillated plant fibers in the aqueous solution of microfibrillated plant fibers is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 3.0% by mass or less, and particularly preferably 1.0% by mass or less.

[0099] In each step, other components (such as the other fillers described above) may be mixed as appropriate. After step 3, for example, a finishing kneading step of kneading a vulcanizing agent and a vulcanization accelerator, and a vulcanization step of performing vulcanization treatment such as press vulcanization are carried out, thereby making it possible to prepare a vulcanized rubber composition.

[0100] The rubber composition can be suitably used for various components of a pneumatic tire, such as a cap tread, a base tread, a sidewall, a bead apex, a clinch apex, an inner liner, an undertread, a breaker topping, a brite topping, an insert (sidewall reinforcing layer), etc. In particular, the rubber composition can be suitably used for a cap tread.

[0101] <Tires> A tire is manufactured by a conventional method using a rubber composition. That is, the rubber composition containing the above components is extruded in an unvulcanized state to match the shape of a cap tread or the like, and then molded together with other tire components in a tire building machine by a conventional method to form an unvulcanized tire. The unvulcanized tire is then heated and pressurized in the vulcanizer to obtain a tire.

[0102] Examples of the tire include pneumatic tires and non-pneumatic tires. Among these, pneumatic tires are preferred. The tire can be used for passenger car tires, large passenger car tires, large SUV tires, heavy-duty tires such as trucks and buses, light truck tires, motorcycle tires, racing tires (high-performance tires), run-flat tires, etc. Among these, the tire can be suitably used for passenger car tires. [Example]

[0103] The present disclosure will be specifically described based on examples, but the present disclosure is not limited to these examples.

[0104] The various chemicals used in the examples and comparative examples will be collectively described below. Microfibrillated plant fiber: Biomass nanofiber manufactured by Sugino Machine Co., Ltd. (product name: "BiNFi-s Cellulose", solid content 2% by mass, moisture 98% by mass, average fiber diameter 20 nm, average fiber length 2000 nm) Vegetable oil: soybean oil manufactured by Nisshin Oillio Co., Ltd. Mineral oil: PS-32 manufactured by Idemitsu Kosan Co., Ltd. Biomass-derived wax 1: Beeswax (beeswax (solid wax at room temperature), manufactured by Sin) Biomass-derived wax 2: Jojoba oil (additive-free, unrefined golden jojoba oil (liquid wax at room temperature), manufactured by Sin) Fat: Shea butter (certified organic refined shea butter (solid fat at room temperature), made by Sin) Lower fatty acid ester: Methyl salicylate (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.) ) NR:TSR20 SBR: Nipol 1502 (E-SBR, styrene content 23.5% by mass) manufactured by Zeon Corporation BR: BR150B (cis content 98% by mass) manufactured by Ube Industries, Ltd. Carbon black: Diablack N220 (N2SA111m) manufactured by Mitsubishi Chemical Corporation 2 / g) Silica: Ultrasil VN3 (N2SA175m) manufactured by Evonik Degussa 2 / g) Silane coupling agent: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa Wax: Ozoace wax manufactured by Nippon Seiro Co., Ltd. Antioxidant: Nocrac 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Stearic acid: NOF Corporation's "Tsubaki" stearic acid Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Co., Ltd. Vulcanization accelerator 1: Noccela NS (N-tert-butyl-2-benzothiazolyl sulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: Noccela D (diphenyl guanidine) manufactured by Ouchi Shinko Chemical Co., Ltd.

[0105] <Preparation of a mixture of at least one selected from the group consisting of fats, biomass-derived waxes, and lower fatty acid esters having 12 or less carbon atoms, vegetable oil or mineral oil, and microfibrillated plant fibers> According to the formulations in Tables 1 and 2, fat, biomass-derived wax, or lower fatty acid ester having 12 or less carbon atoms was mixed with vegetable oil or mineral oil using an IKA high-speed homogenizer T25. The prepared mixture was adjusted to 70°C and brought into a molten state, and then microfibrillated plant fibers were added and mixed according to the formulations in Tables 1 and 2. After mixing, the temperature of the resulting mixture was adjusted to 40°C, and after further stirring, the temperature was adjusted to 23°C to obtain a solid mixture.

[0106] <Preparation of Rubber Composition> Chemicals other than sulfur and vulcanization accelerators were kneaded using a 1.7 L Banbury mixer according to the compounding recipes in Tables 3 to 5. Next, sulfur and vulcanization accelerators were added to the resulting kneaded mixture using a roll and kneaded to obtain an unvulcanized rubber composition, which was then press-vulcanized at 170°C for 15 minutes to obtain a vulcanized rubber composition.

[0107] <Tire manufacturing> According to the compounding formulations in Tables 3 to 5, chemicals other than sulfur and vulcanization accelerator were kneaded for 4 minutes at 150°C using a 1.7L Banbury mixer manufactured by Kobe Steel, Ltd., then sulfur and vulcanization accelerator were added, and the mixture was kneaded for 5 minutes at 80°C using an open roll to prepare an unvulcanized rubber composition. The unvulcanized rubber composition was then molded into the shape of a cap tread, bonded together with other tire components on a tire building machine, and press-vulcanized for 20 minutes at 170°C to prepare a test tire (195 / 65R15).

[0108] The properties of the vulcanized rubber compositions and test tires prepared were measured as follows, and the results are shown in Tables 3, 4 and 5. In the following evaluations, the evaluation criteria for calculating the index are as follows: Table 3: Comparative Example 1-1 Table 4: Comparative Example 2-1 Table 5: Comparative Example 3-1

[0109] <Rubber strength> For each M100 vulcanized rubber composition, a tensile test was conducted at 23°C and 500 mm / min in accordance with JIS K6251:2010 "Vulcanized rubber and thermoplastic rubber - Determination of tensile properties," and the stress (MPa) at 100% elongation was measured. The M100 of the reference comparative example was set to 100, and each formulation was expressed as an index. The higher the index, the better the rubber strength.

[0110] <Dry grip performance> Each test tire was mounted on all wheels of a vehicle (domestic FF 2000cc) and the braking distance from an initial speed of 100 km / h on a dry asphalt road was measured. The braking distance of the reference comparative example was set to 100, and each compounding was expressed as an index. The higher the index, the better the dry grip performance.

[0111] [Table 1]

[0112] [Table 2]

[0113] [Table 3]

[0114] [Table 4]

[0115] [Table 5]

[0116] From each table, it can be seen that the rubber compositions and tires of the examples containing a rubber component, microfibrillated plant fibers, and an ester-based compound had significantly superior overall performance in terms of rubber strength and grip performance (expressed as the sum of two indices, rubber strength and dry grip performance).

[0117] The present disclosure (1) is a rubber composition for tires, comprising a rubber component, microfibrillated plant fibers, and at least one selected from the group consisting of fat, biomass-derived wax, and lower fatty acid esters having 12 or less carbon atoms.

[0118] The present disclosure (2) is the rubber composition for a tire according to the present disclosure (1), which contains at least one selected from the group consisting of the fat and the biomass-derived wax.

[0119] The present disclosure (3) is a rubber composition for tires according to the present disclosure (1) or (2), which contains shea butter.

[0120] The present disclosure (4) is a rubber composition for a tire according to any one of the present disclosures (1) to (3), which contains at least one wax selected from the group consisting of beeswax and jojoba wax.

[0121] The present disclosure (5) is a rubber composition for a tire according to any one of the present disclosures (1) to (4), wherein the total content of the fat, the biomass-derived wax, and the lower fatty acid ester having 12 or less carbon atoms is 100 parts by mass or more per 100 parts by mass of the microfibrillated plant fibers.

[0122] The present disclosure (6) is a rubber composition for a tire according to any one of the present disclosures (1) to (5), which contains vegetable oil or mineral oil.

[0123] The present disclosure (7) is a rubber composition for a tire according to any one of the present disclosures (1) to (6), wherein the content of the isoprene-based rubber in 100% by mass of the rubber component is 50% by mass or more.

[0124] The present disclosure (8) includes styrene butadiene rubber and butadiene rubber. The rubber composition for a tire according to any one of the present disclosures (1) to (7), wherein the total content of the styrene-butadiene rubber and the butadiene rubber in 100% by mass of the rubber component is 50% by mass or more.

[0125] The present disclosure (9) is a tire using the rubber composition of any one of the present disclosures (1) to (8).

Claims

1. The rubber composition comprises a rubber component, microfibrillated plant fibers, and at least one selected from the group consisting of fat, a biomass-derived wax, and a lower fatty acid ester having 12 or less carbon atoms, A rubber composition for tires containing shea butter.

2. A rubber composition comprising a rubber component, microfibrillated plant fibers, and at least one selected from the group consisting of fats, biomass-derived waxes, and lower fatty acid esters having 12 or less carbon atoms, Styrene butadiene rubber and butadiene rubber, The rubber composition for tires has a total content of the styrene-butadiene rubber and the butadiene rubber of 50% by mass or more based on 100% by mass of the rubber component.

3. A rubber composition comprising a rubber component, microfibrillated plant fibers, and at least one selected from the group consisting of fats, biomass-derived waxes, and lower fatty acid esters having 12 or less carbon atoms, A rubber composition for tires containing a wax other than the biomass-derived wax.

4. 4. The rubber composition for a tire according to claim 1, further comprising at least one selected from the group consisting of the fat and the wax derived from biomass.

5. The rubber composition for a tire according to any one of claims 2 to 4, which contains shea butter.

6. The rubber composition for a tire according to any one of claims 1 to 5, which contains at least one wax selected from the group consisting of beeswax and jojoba wax.

7. 7. The rubber composition for a tire according to claim 1, wherein the total content of the fat, the biomass-derived wax, and the lower fatty acid ester having 12 or less carbon atoms is 100 parts by mass or more relative to 100 parts by mass of the microfibrillated plant fibers.

8. The rubber composition for a tire according to any one of claims 1 to 7, which contains vegetable oil or mineral oil.

9. 9. The rubber composition for a tire according to claim 1, wherein the content of the isoprene-based rubber in 100% by mass of the rubber component is 50% by mass or more.

10. Styrene butadiene rubber and butadiene rubber The rubber composition for tires according to any one of claims 1 and 3 to 9, wherein the total content of the styrene-butadiene rubber and the butadiene rubber in 100% by mass of the rubber component is 50% by mass or more.

11. A tire using the rubber composition of any one of claims 1 to 10.

Images