Tire rubber composition, and tire

Abstract

The present invention addresses the problem of providing a tire rubber composition that has excellent resistance to ozone, and high retention rates for elongation at break (EB) and tensile strength (TB) after aging. The means for solving said problem is a tire rubber composition characterized by including a rubber component, an amine-based antioxidant represented by general formula (1) (in the formula, R1 and R2 are each independently a monovalent saturated hydrocarbon group), and a quinoline-based antioxidant, wherein the amine-based antioxidant content is 5 to 10 parts by mass relative to 100 parts by mass of the rubber component, and the quinoline-based antioxidant content is 0.1 to 5 parts by mass relative to 100 parts by mass of the rubber component.

Description

Rubber composition for tires and tires

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

[0002] In general, various rubber components constituting tires may deteriorate due to the influence of external environments such as the presence of ozone, and as this deterioration progresses, cracks and other defects may occur. To address this problem, rubber compositions containing antioxidants are often applied to the various rubber components constituting tires. For example, Patent Document 1 below discloses that cracks and discoloration of the tire surface can be suppressed by applying a rubber composition containing a selected blend of a specific quinoline-based antioxidant and N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (antiaging agent 6PPD) to the rubber constituting the tire surface.

[0003] International Publication No. 2018 / 056384

[0004] However, the N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (antiaging agent 6PPD) used in Patent Document 1 may have an impact on the environment, and it is desirable to use an antioxidant that places less strain on the environment, taking into account the possibility of future restrictions under European regulations. While it may be possible to avoid using the antiaging agent 6PPD in the rubber composition, the inventors' investigations have revealed that using only a quinoline-based antiaging agent without the antiaging agent 6PPD reduces the ozone resistance of the rubber composition, and significantly reduces the durability of the rubber composition after aging (particularly the elongation at break (EB) and tensile strength (TB)).

[0005] Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional art and to provide a rubber composition for a tire that has excellent ozone resistance and a high retention rate of elongation at break (EB) and tensile strength (TB) after aging even without using the antioxidant 6PPD.A further object of the present invention is to provide a tire that has excellent ozone resistance and excellent durability after aging.

[0006] The rubber composition for a tire and the tire of the present invention that solve the above problems are summarized as follows.

[0007] [1] A rubber component and a compound represented by the following general formula (1): [In the formula, R １ and R ２ and each independently represent a monovalent saturated hydrocarbon group, and a quinoline antioxidant, wherein the amount of the amine antioxidant is 5 to 10 parts by mass per 100 parts by mass of the rubber component, and the amount of the quinoline antioxidant is 0.1 to 5 parts by mass per 100 parts by mass of the rubber component.

[0008] [2] The rubber composition for a tire according to [1], wherein the rubber component contains at least one rubber selected from the group consisting of an isoprene skeleton rubber, a styrene-butadiene rubber, a butadiene rubber, and a chloroprene rubber.

[0009] [3] The rubber composition for a tire according to [1] or [2], wherein the quinoline-based antioxidant contains a polymer of 2,2,4-trimethyl-1,2-dihydroquinoline.

[0010] [4] R in the above general formula (1) １ and R ２ are each independently a linear or cyclic monovalent saturated hydrocarbon group having 1 to 20 carbon atoms.

[0011] [5] The rubber composition for a tire according to any one of [1] to [4], further comprising a wax, and the content of the wax is 0.1 to 5 parts by mass per 100 parts by mass of the rubber component.

[0012] [6] A tire comprising a rubber member made of the rubber composition for a tire according to any one of [1] to [5].

[0013] According to the present invention, it is possible to provide a rubber composition for a tire that has excellent ozone resistance and a high retention rate of elongation at break (EB) and tensile strength (TB) after aging. Also, according to the present invention, it is possible to provide a tire that has excellent ozone resistance and excellent durability after aging.

[0014] The rubber composition for a tire and the tire of the present invention will be described in detail below by way of example based on embodiments thereof.

[0015] <Rubber Composition for Tire> The rubber composition for tire of the present invention comprises a rubber component and a compound represented by the following general formula (1): [In the formula, R １ and R ２ and each independently represent a monovalent saturated hydrocarbon group], and a quinoline-based antioxidant. The rubber composition for a tire of the present invention is characterized in that the amount of the amine-based antioxidant is 5 to 10 parts by mass per 100 parts by mass of the rubber component, and the amount of the quinoline-based antioxidant is 0.1 to 5 parts by mass per 100 parts by mass of the rubber component.

[0016] In the rubber composition for a tire of the present invention, the amine-based antioxidant represented by the above general formula (1) is used in combination with a quinoline-based antioxidant, and the content of the amine-based antioxidant is set to 5 parts by mass or more per 100 parts by mass of the rubber component, and the content of the quinoline-based antioxidant is set to 0.1 parts by mass or more per 100 parts by mass of the rubber component, thereby ensuring sufficient ozone resistance of the rubber composition and suppressing decreases in the elongation at break (EB) and tensile strength (TB) of the rubber composition after aging. Therefore, the rubber composition for a tire of the present invention has excellent ozone resistance and a high retention rate of elongation at break (EB) and tensile strength (TB) after aging.

[0017] In addition, in the rubber composition for tires of the present invention, by controlling the content of the amine-based antioxidant to 10 parts by mass or less per 100 parts by mass of the rubber component and the content of the quinoline-based antioxidant to 5 parts by mass or less per 100 parts by mass of the rubber component, it is possible to suppress adverse effects on rubber physical properties other than ozone resistance (heat buildup, etc.), making the composition suitable for tire applications. Furthermore, the amine-based antioxidant represented by the above general formula (1) contained in the rubber composition for tires of the present invention is preferably a quinone-based antioxidant represented by the general formula (1) １ and R ２ is a monovalent saturated hydrocarbon group, which also has the advantage of being environmentally friendly.

[0018] (Rubber Component) The rubber composition for tires of the present invention contains a rubber component, and the rubber component provides rubber elasticity to the composition. As the rubber component, a diene rubber is preferred, and an isoprene-skeleton rubber, a styrene-butadiene rubber (SBR), a butadiene rubber (BR), or a chloroprene rubber (CR) is more preferred. Here, the isoprene-skeleton rubber is a rubber having an isoprene unit as the main skeleton, and specific examples include natural rubber (NR) and synthetic isoprene rubber (IR). When the rubber component contains at least one selected from the group consisting of an isoprene-skeleton rubber, a styrene-butadiene rubber, a butadiene rubber, and a chloroprene rubber, the rubber composition has excellent rubber elasticity and is more suitable for tire applications. Furthermore, when the rubber component contains at least one rubber selected from the group consisting of isoprene-skeleton rubber, styrene-butadiene rubber, butadiene rubber, and chloroprene rubber, the effects of the present invention (the effect of improving ozone resistance by using an amine-based antioxidant in combination with a quinoline-based antioxidant, and the effect of suppressing decreases in elongation at break (EB) and tensile strength (TB) after aging) are more likely to be significantly exhibited. The content of diene rubber, such as isoprene-skeleton rubber, styrene-butadiene rubber, butadiene rubber, or chloroprene rubber, in the rubber component is preferably 80% by mass or more, more preferably 90% by mass or more, and may even be 100% by mass. The rubber component may contain one type alone or a blend of two or more types.

[0019] (Amine-Based Antiaging Agent) The rubber composition for tires of the present invention contains an amine-based antiaging agent represented by the above general formula (1). The amine-based antiaging agent represented by general formula (1) contains a phenylenediamine moiety, just like N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (antiaging agent 6PPD), but differs from antioxidant 6PPD in that it does not contain a double bond outside of the phenylenediamine moiety. The amine-based antiaging agent represented by general formula (1) improves the ozone resistance of the rubber composition and has the effect of suppressing a decrease in the retention rate of elongation at break (EB) and tensile strength (TB) after aging.

[0020] In the above general formula (1), R １ and R ２ are each independently a monovalent saturated hydrocarbon group. １and R ２ may be the same or different, but from the viewpoint of synthesis, they are preferably the same.

[0021] The number of carbon atoms in the monovalent saturated hydrocarbon group is preferably 1 to 20, more preferably 3 to 10, and particularly preferably 6 or 7. When the number of carbon atoms in the saturated hydrocarbon group is 20 or less, the number of moles per unit mass increases, which enhances the anti-aging effect and improves the ozone resistance of the rubber composition. １ and R ２ From the viewpoint of further improving the ozone resistance of the rubber composition, it is preferable that each of the groups independently represents a linear or cyclic monovalent saturated hydrocarbon group having 1 to 20 carbon atoms.

[0022] Examples of the monovalent saturated hydrocarbon group include an alkyl group and a cycloalkyl group. The alkyl group may be linear or branched, and the cycloalkyl group may further have an alkyl group or the like bonded thereto as a substituent. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a 1,2-dimethylbutyl group, a 1,3-dimethylbutyl group, a 2,3-dimethylbutyl group, an n-pentyl group, an isopentyl group, a neopentyl group, a 1-methylpentyl group, a 2-methylpentyl group, a 3-methylpentyl group, a 4-methylpentyl group, a 1,2-dimethylpentyl group, a 1,3-dimethylpentyl group, a 1,4-dimethylpentyl group, a 2,3-dimethylpentyl group, a 2,4-dimethylpentyl group, a 3,4-dimethylpentyl group, an n-hexyl group, a 1-methylhexyl group, a 2-methylhexyl group, various octyl groups, various decyl groups, and various dodecyl groups. Of these, a 1,4-dimethylpentyl group is preferred. Examples of the cycloalkyl group include a cyclopentyl group, a methylcyclopentyl group, a cyclohexyl group, a methylcyclohexyl group, a cycloheptyl group, and a cyclooctyl group, and among these, a cyclohexyl group is preferred.

[0023] Specific examples of the amine-based antioxidant represented by the general formula (1) include N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (antiaging agent 77PD), N,N'-bis(1-ethyl-3-methylpentyl)-p-phenylenediamine, and N,N'-dicyclohexyl-p-phenylenediamine (antiaging agent CCPD). Of these, N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (antiaging agent 77PD) and N,N'-dicyclohexyl-p-phenylenediamine (CCPD) are preferred, with N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (antiaging agent 77PD) being particularly preferred. The amine-based antioxidants may be used alone or in combination of two or more.

[0024] The content of the amine-based antioxidant is 5 to 10 parts by mass per 100 parts by mass of the rubber component. If the content of the amine-based antioxidant is less than 5 parts by mass per 100 parts by mass of the rubber component, the ozone resistance of the rubber composition cannot be sufficiently ensured, and the decrease in the elongation at break (EB) and tensile strength (TB) of the rubber composition after aging cannot be sufficiently suppressed. On the other hand, if the content of the amine-based antioxidant exceeds 10 parts by mass per 100 parts by mass of the rubber component, adverse effects on rubber physical properties other than ozone resistance (heat buildup, etc.) become significant, making the rubber unsuitable for tire applications. From the viewpoint of ozone resistance, the content of the amine-based antioxidant is preferably 5.5 parts by mass or more, more preferably 6 parts by mass or more, per 100 parts by mass of the rubber component. Furthermore, from the viewpoint of the influence on other rubber physical properties, the content is preferably 9.5 parts by mass or less, more preferably 9 parts by mass or less, per 100 parts by mass of the rubber component.

[0025] (Quinoline-Based Antiaging Agent) The rubber composition for a tire of the present invention contains a quinoline-based antioxidant. The quinoline-based antioxidant is an antioxidant having a quinoline moiety or a derivative thereof (such as a dihydroquinoline moiety). The quinoline-based antioxidant has the effect of improving the ozone resistance of the rubber composition and suppressing a decrease in the retention rate of elongation at break (EB) and tensile strength (TB) after aging.

[0026] The quinoline-based antioxidant preferably has a dihydroquinoline moiety, and more preferably has a 1,2-dihydroquinoline moiety. Specific examples of the quinoline-based antioxidant include a polymer of 2,2,4-trimethyl-1,2-dihydroquinoline (antiaging agent TMDQ), 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, and 6-anilino-2,2,4-trimethyl-1,2-dihydroquinoline. The quinoline-based antioxidant preferably contains a polymer of 2,2,4-trimethyl-1,2-dihydroquinoline (antiaging agent TMDQ). Quinoline-based antioxidants containing a polymer of 2,2,4-trimethyl-1,2-dihydroquinoline are highly effective in improving the ozone resistance of rubber compositions and also have the advantage of being less likely to discolor the rubber composition. The polymer of 2,2,4-trimethyl-1,2-dihydroquinoline includes a dimer, trimer, tetramer, etc. of 2,2,4-trimethyl-1,2-dihydroquinoline.

[0027] The content of the quinoline-based antioxidant is 0.1 to 5 parts by mass per 100 parts by mass of the rubber component. If the content of the quinoline-based antioxidant is less than 0.1 part by mass per 100 parts by mass of the rubber component, the ozone resistance of the rubber composition cannot be sufficiently ensured, and the decrease in the elongation at break (EB) and tensile strength (TB) of the rubber composition after aging cannot be sufficiently suppressed. On the other hand, if the content of the quinoline-based antioxidant exceeds 5 parts by mass per 100 parts by mass of the rubber component, adverse effects on rubber physical properties other than ozone resistance (heat buildup, etc.) become significant, making the rubber unsuitable for tire applications. From the viewpoint of ozone resistance, the content of the quinoline-based antioxidant is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, per 100 parts by mass of the rubber component. Furthermore, from the viewpoint of the influence on other rubber physical properties, the content is preferably 4 parts by mass or less, more preferably 3 parts by mass or less, per 100 parts by mass of the rubber component.

[0028] (Wax) The rubber composition for a tire of the present invention preferably further contains a wax. When the rubber composition contains a wax, the ozone resistance of the rubber composition is further improved. Examples of the wax include paraffin wax and microcrystalline wax. The content of the wax is preferably 0.1 to 5 parts by mass per 100 parts by mass of the rubber component. When the content of the wax is 0.1 part by mass or more per 100 parts by mass of the rubber component, the ozone resistance of the rubber composition is further improved. Furthermore, when the content of the wax is 5 parts by mass or less per 100 parts by mass of the rubber component, the influence on rubber physical properties other than ozone resistance is small. From the viewpoint of ozone resistance, the content of the wax is more preferably 0.5 parts by mass or more per 100 parts by mass of the rubber component, and even more preferably 1 part by mass or more. Furthermore, from the viewpoint of the influence on other rubber physical properties, the content of the wax is more preferably 4 parts by mass or less per 100 parts by mass of the rubber component, and even more preferably 3 parts by mass or less.

[0029] (Sulfur) The rubber composition for a tire of the present invention preferably contains sulfur. The inclusion of sulfur in the rubber composition makes it possible to vulcanize the rubber composition, improving its durability (particularly, elongation at break (EB) and tensile strength (TB)). Various types of sulfur can be used as the sulfur; however, ordinary sulfur (soluble sulfur (powdered sulfur), etc.) is preferred over insoluble sulfur, and oil treat sulfur is also preferred. Here, insoluble sulfur refers to sulfur insoluble in carbon disulfide (amorphous polymeric sulfur), and soluble sulfur (powdered sulfur) refers to sulfur soluble in carbon disulfide. The sulfur content is preferably in the range of 0.1 to 10 parts by mass, more preferably 1 to 5 parts by mass, per 100 parts by mass of the rubber component. When the sulfur content is 0.1 part by mass or more per 100 parts by mass of the rubber component, the durability of the vulcanized rubber can be ensured. When the sulfur content is 10 parts by mass or less per 100 parts by mass of the rubber component, sufficient rubber elasticity can be ensured.

[0030] (Others) In addition to the rubber component, amine-based antioxidant, quinoline-based antioxidant, wax, and sulfur described above, the rubber composition for tires of the present invention may contain various components commonly used in the rubber industry, such as fillers (silica, carbon black, calcium carbonate, etc.), silane coupling agents, softeners, processing aids, resins, surfactants, organic acids (stearic acid, etc.), zinc oxide (zinc white), vulcanization accelerators, and vulcanizing agents other than sulfur, as needed, as long as they do not impair the objectives of the present invention. Commercially available products can be suitably used as these compounding ingredients. The amine-based antioxidant represented by the general formula (1) may be supported on any carrier. For example, the amine-based antioxidant represented by the general formula (1) may be supported on an inorganic filler such as silica or calcium carbonate. The amine-based antioxidant represented by the general formula (1) may also be used as a masterbatch with the rubber component. The rubber component used in preparing the masterbatch is not particularly limited, and may be a diene rubber such as natural rubber (NR), or an ethylene-propylene-diene rubber (EPDM). The amine-based antioxidant represented by the general formula (1) may be a salt with an organic acid. The organic acid used in preparing the salt is not particularly limited, but examples thereof include stearic acid.

[0031] (Method for Producing Rubber Composition) The method for producing the rubber composition is not particularly limited, but the rubber composition can be produced, for example, by blending the above-mentioned rubber component, amine-based antioxidant, and quinoline-based antioxidant with various components appropriately selected as necessary, followed by kneading, heating, extrusion, etc. The obtained rubber composition can be vulcanized to produce a vulcanized rubber.

[0032] The conditions for the kneading are not particularly limited, and various conditions such as the input volume of the kneading device, the rotation speed of the rotor, the ram pressure, the kneading temperature, the kneading time, the type of kneading device, etc. can be appropriately selected depending on the purpose. Examples of the kneading device include a Banbury mixer, an intermix, a kneader, a roll, etc. that are usually used for kneading rubber compositions.

[0033] The conditions for the heat-in are not particularly limited, and various conditions such as the heat-in temperature, heat-in time, and heat-in device can be appropriately selected depending on the purpose. Examples of the heat-in device include a heat-in roll mill typically used for heat-in of rubber compositions.

[0034] The extrusion conditions are not particularly limited, and various conditions such as extrusion time, extrusion speed, extrusion device, and extrusion temperature can be appropriately selected depending on the purpose. Examples of the extrusion device include an extruder typically used for extruding rubber compositions. The extrusion temperature can be appropriately determined.

[0035] The vulcanization apparatus, method, conditions, etc. are not particularly limited and can be appropriately selected depending on the purpose. Examples of vulcanization apparatus include a molding vulcanizer using a mold used for vulcanizing rubber compositions. The vulcanization temperature is, for example, about 100 to 190°C.

[0036] <Tire> The tire of the present invention is characterized by comprising a rubber component made of the above-described rubber composition for a tire. The tire of the present invention comprises a rubber component made of the above-described rubber composition for a tire, and therefore has excellent ozone resistance and durability after aging. The tire of the present invention also has the advantage of being environmentally friendly. Suitable rubber components to which the above-described rubber composition for a tire is applied include side rubber, tread rubber, inner liner, and the like that constitute the tire surface. Note that the rubber component to which the above-described rubber composition for a tire is applied may also be a rubber component that constitutes the interior of the tire, and examples of such rubber components include bead fillers and coating rubbers for reinforcing components such as carcasses and belts.

[0037] Depending on the type of tire to be applied, the tire of the present invention may be obtained by molding an unvulcanized rubber composition and then vulcanizing it, or by molding a semi-vulcanized rubber that has been subjected to a pre-vulcanization step or the like and then further vulcanizing it. The tire of the present invention is preferably a pneumatic tire, and the gas to be filled into the pneumatic tire may be normal air or air with an adjusted oxygen partial pressure, or an inert gas such as nitrogen, argon, or helium.

[0038] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples in any way.

[0039] Comparative Example 1 (Preparation of Rubber Composition) A rubber composition of Comparative Example 1 was produced according to the compounding recipe shown in Table 1. Table 2 shows the compounding amount of the antioxidant used.

[0040]

[0041] * 1 NR: Natural rubber * 2 SBR: Styrene-butadiene rubber [bound styrene amount = 20% by mass, vinyl bond amount in butadiene portion = 55% by mass, glass transition temperature (Tg) = -40 ° C.] and styrene-butadiene rubber oil-extended rubber [bound styrene amount = 45% by mass, vinyl bond amount in butadiene portion = 19% by mass, glass transition temperature (Tg) = -30 ° C.], total amount (including 12 parts by mass of oil extension) * 3 Silica: Tosoh Silica Industry Co., Ltd., trade name "Nipsil AQ" * 4 Carbon black: Asahi Carbon Co., Ltd., trade name "Asahi # 78" * 5 Wax: Microcrystalline wax, total amount of Nippon Seiro Co., Ltd. trade name "Ozoace 0701" and Nippon Seiro Co., Ltd. trade name "Ozoace 0301" * 6 Antioxidant 77PD: R in general formula (1) １ and R ２ *6 Antioxidant TMDQ: quinoline-based antioxidant, 2,2,4-trimethyl-1,2-dihydroquinoline polymer *7 Sulfur: Hosoi Chemical Industry Co., Ltd., trade name "HK200-5", 5% oil *8 Other chemicals: a total amount including at least Shin-Etsu Chemical Co., Ltd., trade name "ABC-856" (silane coupling agent), NOF Corporation, trade name "Kiri Stearic Acid" (stearic acid), Hakusui Tech Co., Ltd., Sanshin Chemical Industry Co., Ltd., trade name "Suncerer CM-G" (accelerator), and Kao Corporation, trade name "MS-95"

[0042] (Evaluation of Rubber Composition) The obtained rubber compositions were evaluated for the retention of elongation at break (EB) and tensile strength (TB) after aging, and for ozone resistance, by the following methods. The results are shown in Table 2.

[0043] (1) Retention Rate of Elongation at Break (EB) and Tensile Strength (TB) After Aging A rubber composition was vulcanized to prepare a vulcanized rubber test piece. Immediately after preparation, the test piece was subjected to a tensile test in accordance with JIS K 6251 to measure the initial elongation at break (EB) and tensile strength (TB). Next, the vulcanized rubber test piece was left to age at 100°C for 24 hours, and the aged test piece was subjected to a tensile test in accordance with JIS K 6251 to measure the elongation at break (EB) and tensile strength (TB) after aging.

[0044] The retention rates of elongation at break (EB) and tensile strength (TB) after aging were calculated from the initial elongation at break (EB) and tensile strength (TB) and the elongation at break (EB) and tensile strength (TB) after aging according to the following formula: Retention rate of elongation at break (EB) after aging = elongation at break (EB) after aging / initial elongation at break (EB) × 100 (%) Retention rate of tensile strength (TB) after aging = tensile strength after aging (TB) / initial tensile strength (TB) × 100 (%)

[0045] (2) Ozone Resistance A dynamic ozone degradation test (a test in which repeated strain is applied) and a static ozone degradation test (a test in which a constant strain is applied and left to stand) were conducted in accordance with JIS K 6259-1 to evaluate ozone resistance. The evaluation involved ranking the number of cracks and classifying them according to the following criteria (A to C), as well as ranking the size and depth of the cracks and classifying them according to the following criteria (1 to 5).

[0046] --Ranking by number of cracks-- A: Few cracks B: Many cracks C: Numerous cracks

[0047] --Ranking by size and depth of cracks-- 1: Not visible to the naked eye but visible with a 10x magnifying glass. 2: Visible to the naked eye. 3: Relatively large, deep crack (less than 1 mm). 4: Large, deep crack (1 mm or more but less than 3 mm). 5: Cracks of 3 mm or larger or likely to cause cuts.

[0048] Examples 1 and 2 and Comparative Example 2 Rubber compositions were produced according to the compounding recipes shown in Tables 1 and 2, and the retention rates of elongation at break (EB) and tensile strength (TB) after aging and ozone resistance were evaluated using the methods described above.

[0049] <Evaluation of Heat Buildup> Using an ARES-G2 (manufactured by TA Instruments), the tan δ (50°C) of each vulcanized rubber (cylindrical shape with Φ = 8 mm and height = 6 mm) was measured under conditions of a shear deformation strain rate of 10%, a frequency of 15 Hz, and a temperature of 50°C. The evaluation results of tan δ (50°C) of each vulcanized rubber are shown in the "Heat Buildup" column as an index, with the tan δ (50°C) of the standard example (Comparative Example 1) set to 100. A smaller heat buildup index indicates better rolling performance (low rolling resistance).

[0050]

[0051] From Table 2, it can be seen that when the content of the amine-based antioxidant represented by the general formula (1) is 5 to 10 parts by mass per 100 parts by mass of the rubber component and the content of the quinoline-based antioxidant is 0.1 to 5 parts by mass per 100 parts by mass of the rubber component, excellent ozone resistance and high retention rates of elongation at break (EB) and tensile strength (TB) after aging are achieved even without the use of antioxidant 6PPD. Also, from Comparative Example 2, it can be seen that when the content of the amine-based antioxidant represented by the general formula (1) exceeds 10 parts by mass per 100 parts by mass of the rubber component, heat buildup deteriorates.

Claims

1. a rubber component, the following general formula (1): 【Chemical 1】 [In the formula, R １ and R ２ are each independently a monovalent saturated hydrocarbon group], and an amine-based antioxidant represented by a quinoline-based antioxidant, and contains, the content of the amine-based antioxidant is 5 to 10 parts by mass with respect to 100 parts by mass of the rubber component, the content of the quinoline-based antioxidant is 0.1 to 5 parts by mass with respect to 100 parts by mass of the rubber component, a rubber composition for a tire, characterized in that.

2. The rubber composition for a tire according to claim 1, wherein the rubber component contains at least one selected from the group consisting of isoprene skeleton rubber, styrene-butadiene rubber, butadiene rubber, and chloroprene rubber.

3. The rubber composition for a tire according to claim 1, wherein the quinoline-based antioxidant contains a polymer of 2,2,4-trimethyl-1,2-dihydroquinoline.

4. R in the general formula (1) above １ and R ２ The rubber composition for tires according to claim 1, wherein each is independently a linear or cyclic monovalent saturated hydrocarbon group having 1 to 20 carbon atoms.

5. The rubber composition for a tire according to claim 1, further comprising wax, and the content of the wax is 0.1 to 5 parts by mass with respect to 100 parts by mass of the rubber component.

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

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