Rubber composition for tires and tires

Abstract

The present invention provides 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. This tire rubber composition is characterized by including a rubber component, an amine-based antioxidant represented by prescribed general formula (1), and a quinoline-based antioxidant, wherein the amine-based antioxidant content is 0.1 to 11 parts by mass relative to 100 parts by mass of the rubber component, and the quinoline-based antioxidant content is 0.1 to 0.95 parts by mass relative to 100 parts by mass of the rubber component.

Description

[Technical Field]

[0001] This invention relates to a rubber composition for tires and a tire. [Background technology]

[0002] Generally, the various rubber components that make up a tire can deteriorate due to the influence of external environmental factors such as the presence of ozone, and as this deterioration progresses, cracks and other damage may occur. To address this problem, rubber compositions containing anti-aging agents are often applied to the various rubber components that make up a tire. For example, Patent Document 1 discloses that by applying a rubber composition containing a specific quinoline-based antioxidant and N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (antioxidant 6PPD) to the rubber constituting the surface of a tire, cracks and discoloration of the tire surface can be suppressed. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2018 / 056384 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (anti-aging agent 6PPD) used in the above-mentioned Patent Document 1 may have environmental impacts, and it is desirable to use an anti-aging agent that has a lower environmental impact, including the possibility of future regulations under European laws.Therefore, it is conceivable to not use the anti-aging agent 6PPD in the rubber composition, but the inventors have investigated and found that if only a quinoline-based anti-aging agent is used and the anti-aging agent 6PPD is not used, the ozone resistance of the rubber composition decreases, and the durability of the aged rubber composition (especially elongation at break (EB) and tensile strength (TB)) decreases significantly.

[0005] Therefore, the present invention aims to solve the problems of the above-mentioned prior art and provide a tire rubber composition that exhibits excellent ozone resistance and high retention of elongation at break (EB) and tensile strength (TB) after aging, without the use of the anti-aging agent 6PPD. Furthermore, a further objective of the present invention is to provide a tire that has excellent ozone resistance and excellent durability after aging. [Means for solving the problem]

[0006] The gist of the present invention, which solves the above problems, is as follows.

[0007] [1] Rubber components and, The following general formula (1): [ka] [In the formula, R 1 and R 2 Each of these is an amine-based antioxidant represented by a monovalent saturated hydrocarbon group, It contains a quinoline-based anti-aging agent, The content of the amine-based antioxidant is 0.1 to 11 parts by mass per 100 parts by mass of the rubber component. A rubber composition for tires, characterized in that the content of the quinoline-based antioxidant is 0.1 to 0.95 parts by mass per 100 parts by mass of the rubber component. The rubber composition for tires according to the present invention exhibits excellent ozone resistance and high retention rates of elongation at break (EB) and tensile strength (TB) after aging.

[0008] [2] The tire rubber composition according to [1], wherein the rubber component comprises at least one selected from the group consisting of isoprene backbone rubber, styrene-butadiene rubber, butadiene rubber, and chloroprene rubber. In this case, the rubber composition exhibits excellent rubber elasticity, resulting in a rubber composition more suitable for tire applications, and the effects of the present invention are more readily apparent.

[0009] [3] The tire rubber composition according to [1] or [2], wherein the quinoline-based antioxidant comprises a polymer of 2,2,4-trimethyl-1,2-dihydroquinoline. In this case, the effect of improving the ozone resistance of the rubber composition is enhanced, and the rubber composition becomes less prone to discoloration.

[0010] [4] R in the above general formula (1) 1 and R 2 The tire rubber composition according to any one of [1] to [3], wherein each is independently a chain or cyclic monovalent saturated hydrocarbon group having 1 to 20 carbon atoms. In this case, the ozone resistance of the rubber composition is further improved.

[0011] [5] The tire rubber composition according to any one of [1] to [4], further comprising wax, wherein the amount of wax is 0.1 to 5 parts by mass per 100 parts by mass of the rubber component. In this case, the ozone resistance of the rubber composition is further improved.

[0012] A tire characterized by comprising a rubber member made of a tire rubber composition described in any of [6][1] to [5]. The tire of this invention exhibits excellent ozone resistance and superior durability after aging. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a rubber composition for tires 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.

Embodiments for Carrying Out the Invention

[0014] Hereinafter, the rubber composition for tires and the tire of the present invention will be exemplified and described in detail based on their embodiments. Note that the compounds described in this specification may be partially or entirely derived from fossil resources, may be derived from biological resources such as plant resources, or may be derived from recycled resources such as used tires. Further, they may be derived from a mixture of any two or more of fossil resources, biological resources, and recycled resources.

[0015] <Rubber Composition for Tires> The rubber composition for tires of the present invention contains a rubber component, an amine-based antioxidant represented by the following general formula (1):

Chemical formula

[0016] In the tire rubber composition of the present invention, by using an amine-based antioxidant represented by the above general formula (1) and a quinoline-based antioxidant in combination, and by setting the content of the amine-based antioxidant to 0.1 parts by mass or more per 100 parts by mass of the rubber component, and the content of the quinoline-based antioxidant to 0.1 parts by mass or more per 100 parts by mass of the rubber component, the ozone resistance of the rubber composition can be sufficiently ensured, and the decrease in elongation at break (EB) and tensile strength (TB) of the aged rubber composition can be suppressed. Therefore, the tire rubber composition of the present invention exhibits excellent ozone resistance and high retention of elongation at break (EB) and tensile strength (TB) after aging.

[0017] Furthermore, in the tire rubber composition of the present invention, by setting the content of the amine-based antioxidant to 11 parts by mass or less per 100 parts by mass of the rubber component, and the content of the quinoline-based antioxidant to 0.95 parts by mass or less per 100 parts by mass of the rubber component, adverse effects on rubber properties other than ozone resistance (such as heat generation) can be suppressed, making it suitable for tire applications. Furthermore, the amine-based antioxidant represented by the above general formula (1) contained in the tire rubber composition of the present invention is R in general formula (1). 1 and R 2 Because it is a monovalent saturated hydrocarbon group, it 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 preferable, and an isoprene skeleton rubber, styrene-butadiene rubber (SBR), butadiene rubber (BR), and chloroprene rubber (CR) are more preferable. Here, the isoprene skeleton rubber is a rubber having an isoprene unit as a main skeleton, and specifically, natural rubber (NR), synthetic isoprene rubber (IR), etc. are exemplified. When the rubber component contains at least one selected from the group consisting of an isoprene skeleton rubber, styrene-butadiene rubber, butadiene rubber, and chloroprene rubber, the rubber elasticity of the rubber composition is excellent, and it becomes a rubber composition more suitable for tire applications. Further, when the rubber component contains at least one selected from the group consisting of an isoprene skeleton rubber, styrene-butadiene rubber, butadiene rubber, and chloroprene rubber, the effects of the present invention (the effect of improving ozone resistance by the combined use of an amine-based antioxidant and a quinoline-based antioxidant, the effect of suppressing the decrease in elongation at break (EB) and tensile strength (TB) after aging) are likely to appear remarkably. The content of diene rubbers such as isoprene skeleton rubber, styrene-butadiene rubber, butadiene rubber, and chloroprene rubber in the rubber component is preferably 80% by mass or more, more preferably 90% by mass or more, and may be 100% by mass. The rubber component may be used alone or in a blend of two or more kinds.

[0019] (amine-based antioxidant) The rubber composition for tires of the present invention contains an amine-based antioxidant represented by the above general formula (1). The amine-based antioxidant represented by the general formula (1) contains a phenylenediamine moiety similar to N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (antioxidant 6PPD), but is different from antioxidant 6PPD in that it has no double bond other than the phenylenediamine moiety. Further, the amine-based antioxidant represented by the general formula (1) has an action of improving the ozone resistance of the rubber composition and suppressing the 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 2These are each independently monovalent saturated hydrocarbon groups. 1 and R 2 These may be the same or different, but from a synthesis standpoint, it is preferable that they be 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 and 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. In the above general formula (1), R 1 and R 2 From the viewpoint of further improving the ozone resistance of the rubber composition, it is preferable that each of these is independently a chain or cyclic monovalent saturated hydrocarbon group having 1 to 20 carbon atoms.

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

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

[0024] The content of the amine-based antioxidant is 0.1 to 11 parts by mass per 100 parts by mass of the rubber component. If the content of the amine-based antioxidant is less than 0.1 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 elongation at break (EB) and tensile strength (TB) of the aged rubber composition cannot be sufficiently suppressed. On the other hand, if the content of the amine-based antioxidant exceeds 11 parts by mass per 100 parts by mass of the rubber component, the adverse effects on rubber properties other than ozone resistance (such as heat generation) become significant, making it unsuitable for tire applications. From the viewpoint of ozone resistance, the content of the amine-based antioxidant is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, per 100 parts by mass of the rubber component, and from the viewpoint of affecting other rubber properties, it is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, per 100 parts by mass of the rubber component.

[0025] (Quinoline-based anti-aging agent) The rubber composition for tires of the present invention contains a quinoline-based antioxidant. The quinoline-based antioxidant is an antioxidant having a quinoline portion or a derivative thereof (such as a dihydroquinoline portion). The quinoline-based antioxidant has the effect of improving the ozone resistance of the rubber composition and suppressing the decrease in the maintenance 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. Examples of the aforementioned quinoline-based antioxidants include polymers of 2,2,4-trimethyl-1,2-dihydroquinoline (antioxidant 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 (antioxidant TMDQ). A quinoline-based antioxidant containing a polymer of 2,2,4-trimethyl-1,2-dihydroquinoline has a high effect in improving the ozone resistance of the rubber composition and also has the advantage of being less likely to cause discoloration of the rubber composition. Polymers of 2,2,4-trimethyl-1,2-dihydroquinoline include dimers, trimers, and tetramers of 2,2,4-trimethyl-1,2-dihydroquinoline.

[0027] The content of the quinoline-based antioxidant is 0.1 to 0.95 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 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 elongation at break (EB) and tensile strength (TB) of the aged rubber composition cannot be sufficiently suppressed. On the other hand, if the content of the quinoline-based antioxidant is less than 0.1 parts by mass per 100 parts by mass of the rubber component 0.95If the amount exceeds parts by mass, the adverse effects on rubber properties other than ozone resistance (such as heat generation) become significant, making it 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, and more preferably 0.5 parts by mass or more, per 100 parts by mass of the rubber component. Shii .

[0028] (wax) The rubber composition for tires of the present invention preferably further contains wax. When the rubber composition contains wax, the ozone resistance of the rubber composition is further improved. Examples of the aforementioned waxes include paraffin wax and microcrystalline wax. The amount of wax is preferably 0.1 to 5 parts by mass per 100 parts by mass of the rubber component. If the amount of wax is 0.1 parts by mass or more per 100 parts by mass of the rubber component, the ozone resistance of the rubber composition is further improved. Also, if the amount of wax is 5 parts by mass or less per 100 parts by mass of the rubber component, the effect on rubber properties other than ozone resistance is small. From the viewpoint of ozone resistance, the amount of 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. From the viewpoint of the effect on other rubber properties, it 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 tires of the present invention preferably contains sulfur. The inclusion of sulfur in the rubber composition makes it vulcanizable, which improves the durability of the rubber composition (particularly elongation at break (EB) and tensile strength (TB)). Various types of sulfur can be used as the aforementioned sulfur, but ordinary sulfur (soluble sulfur (powdered sulfur), etc.) is preferred over insoluble sulfur, and oil-treated sulfur is also preferred. Here, insoluble sulfur is sulfur that is insoluble in carbon disulfide (amorphous polymeric sulfur), and soluble sulfur (powdered sulfur) is sulfur that is soluble in carbon disulfide. The sulfur content is preferably in the range of 0.1 to 10 parts by mass per 100 parts by mass of rubber component, and more preferably in the range of 1 to 5 parts by mass. If the sulfur content is 0.1 parts by mass or more per 100 parts by mass of rubber component, the durability of the vulcanized rubber can be ensured, and if it is 10 parts by mass or less per 100 parts by mass of rubber component, sufficient rubber elasticity can be ensured.

[0030] (others) In addition to the rubber components, amine-based antioxidants, quinoline-based antioxidants, waxes, and sulfur described above, the rubber composition for tires of the present invention may optionally 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 oxide), vulcanization accelerators, and vulcanizing agents other than sulfur, selected as appropriate within a range that does not impair the purpose of the present invention. Commercially available products can be suitably used as these compounding agents. The amine-based antioxidant represented by the above general formula (1) may be supported on any carrier. For example, the amine-based antioxidant represented by the above general formula (1) may be supported on an inorganic filler such as silica or calcium carbonate. Furthermore, the amine-based antioxidant represented by the above general formula (1) may also constitute a masterbatch together with the rubber component. The rubber component used when forming the masterbatch is not particularly limited and may be a diene rubber such as natural rubber (NR), or ethylene-propylene-diene rubber (EPDM), etc. Furthermore, the amine-based antioxidant represented by the above general formula (1) may also be in the form of a salt with an organic acid. The organic acid used when forming the salt is not particularly limited, but examples include stearic acid.

[0031] (Method for manufacturing rubber composition) The method for producing the rubber composition is not particularly limited, but for example, it can be produced by mixing the rubber components, amine-based antioxidants, and quinoline-based antioxidants described above with various components as needed, and then kneading, heating, extruding, etc. Furthermore, the obtained rubber composition can be vulcanized to produce vulcanized rubber.

[0032] There are no particular restrictions on the mixing conditions, and various conditions such as the input volume of the mixing device, the rotation speed of the rotor, the ram pressure, as well as the mixing temperature, mixing time, and the type of mixing device can be appropriately selected according to the purpose. Examples of mixing devices include Banbury mixers, intermixes, kneaders, and rolls, which are commonly used for mixing rubber compositions.

[0033] There are no particular restrictions on the heat treatment conditions, and various conditions such as heat treatment temperature, heat treatment time, and heat treatment equipment can be appropriately selected according to the purpose. Examples of such heat treatment equipment include heat treatment roll machines commonly used for heat treatment of rubber compositions.

[0034] There are no particular restrictions on the extrusion conditions, and various conditions such as extrusion time, extrusion speed, extrusion equipment, and extrusion temperature can be appropriately selected according to the purpose. Examples of extrusion equipment include extruders typically used for extruding rubber compositions. The extrusion temperature can be determined as appropriate.

[0035] There are no particular restrictions on the apparatus, method, and conditions for performing the vulcanization, and they can be appropriately selected according to the purpose. Typical vulcanization apparatuses include molding vulcanizers using molds, which are commonly used for vulcanizing rubber compositions. The vulcanization temperature is typically around 100-190°C.

[0036] <Tires> The tire of the present invention is characterized by comprising a rubber member made of the above-described tire rubber composition. Because the tire of the present invention comprises a rubber member made of the above-described tire rubber composition, it has excellent ozone resistance and excellent durability after aging. Furthermore, the tire of the present invention also has the advantage of being environmentally friendly. Suitable rubber components to which the above tire rubber composition is applied include side rubber, tread rubber, and inner liner, which constitute the tire surface. The rubber components to which the above tire rubber composition is applied may also be rubber components that constitute the inside of the tire. Examples of such rubber components include bead fillers and coating rubber for reinforcing members such as carcasses and belts.

[0037] The tire of the present invention may be obtained by molding an unvulcanized rubber composition and then vulcanizing it, depending on the type of tire to be applied, or by molding a semi-vulcanized rubber that has undergone a pre-vulcanization process, and then further vulcanizing it. The tire of the present invention is preferably a pneumatic tire, and as the gas to be filled into the pneumatic tire, in addition to ordinary air or air with adjusted oxygen partial pressure, an inert gas such as nitrogen, argon, or helium can be used. [Examples]

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

[0039] <Example 3> (Preparation of rubber composition) The rubber composition was manufactured according to the formulation shown in Table 1. The amounts of the antioxidants used are shown in Table 2.

[0040] [Table 1]

[0041] *1 NR: Natural rubber *2 SBR: Styrene-butadiene rubber (Total amount of SBR-1: (Styrene-butadiene rubber: amount of bound styrene = 20% by mass, amount of vinyl bound in the butadiene portion = 55% by mass, glass transition temperature (Tg) = -40°C) and SBR-2: (Oil-expanded styrene-butadiene rubber, amount of bound styrene = 45% by mass, amount of vinyl bound in the butadiene portion = 19% by mass, glass transition temperature (Tg) = -30°C). Includes 12 parts by mass of oil-expanded component.) *3 Silica: Manufactured by Tosoh Silica Industry Co., Ltd., product name "NipSeal AQ" *4 Carbon Black: Manufactured by Asahi Carbon Co., Ltd., product name "Asahi #78" *5 Wax: Microcrystalline wax, total amount of "Ozoace 0701" and "Ozoace 0301" manufactured by Nippon Seiro Co., Ltd. *6 Anti-aging agent 77PD: R in general formula (1) 1 and R 2 The amine-based antioxidant, N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine, manufactured by Eastman, has a saturated hydrocarbon group (1,4-dimethylpentyl group) as its base. Trademark: "Santoflex 77PD" *7 Anti-aging agent TMDQ: Quinoline-based anti-aging agent, 2,2,4-trimethyl-1,2-dihydroquinoline polymer *8 Anti-aging agent 6PPD: N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine, manufactured by Sumitomo Chemical Co., Ltd., trade name "Antigen 6C" *9 Sulfur: Manufactured by Hosoi Chemical Industry Co., Ltd., product name "HK200-5", 5% oil *10 Other chemicals: Total amount including at least silane coupling agent (bis(triethoxysilylpropyl) polysulfide, manufactured by Shin-Etsu Chemical Co., Ltd., trade name "ABC-856"), stearic acid (manufactured by NOF Corporation, trade name "Kiri-jirushi Stearic Acid"), zinc oxide manufactured by Hakusui Tech Co., Ltd., trade name "Suncellar CM-G" manufactured by Sanshin Chemical Industry Co., Ltd., and trade name "MS-95" manufactured by Kao Corporation.

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

[0043] (1) Maintenance rate of elongation at break (EB) and tensile strength (TB) after aging Vulcanized rubber test specimens were prepared by vulcanizing the rubber composition. Tensile tests were performed on the test specimens immediately after preparation in accordance with JIS K 6251, and the initial elongation at break (EB) and tensile strength (TB) were measured. Next, vulcanized rubber test pieces were left at 100°C for 24 hours to age. Tensile tests were then performed on the aged test pieces in accordance with JIS K 6251, and the elongation at break (EB) and tensile strength (TB) after aging were measured.

[0044] The maintenance rate of the elongation at break (EB) and tensile strength (TB) after aging was calculated from the initial elongation at break (EB) and tensile strength (TB), as well as the elongation at break (EB) and tensile strength (TB) after aging, according to the following formula. Maintenance rate of rupture elongation (EB) after aging = Relative rupture elongation (EB) after aging / Initial rupture elongation (EB) × 100 (%) Maintenance rate of tensile strength (TB) after aging = Tensile strength after aging (TB) / Initial tensile strength (TB) × 100 (%)

[0045] (2) Ozone resistance In accordance with JIS K 6259-1, dynamic ozone degradation tests (tests involving repeated straining) and static ozone degradation tests (tests involving constant straining and leaving the material unattended) were conducted to evaluate ozone resistance. The evaluation was based on ranking according to the number of cracks, classified according to the following criteria (A-C), and also on ranking according to the size and depth of the cracks, classified according to the following criteria (1-5).

[0046] --Ranking based on the number of cracks-- A: Few cracks B: Numerous cracks C: Numerous cracks

[0047] --Ranking based on crack size and depth-- 1: Something invisible to the naked eye but visible with a 10x magnifying glass. 2: Things that can be seen with the naked eye. 3: Cracks that are deep and relatively large (less than 1 mm). 4. Cracks that are deep and large (1mm to less than 3mm). 5. Items that are likely to develop cracks or breaks of 3 mm or more.

[0048] <Comparative Examples 1-3 and Examples 1, 2, 4> Rubber compositions are manufactured according to the formulations shown in Tables 1 and 2, and the retention rates of elongation at break (EB) and tensile strength (TB) after aging, as well as ozone resistance, are evaluated using the method described above.

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

[0050] [Table 2]

[0051] Table 2 shows that in the examples where the content of the amine-based antioxidant represented by the above general formula (1) is 0.1 to 11 parts by mass per 100 parts by mass of rubber component, and the content of the quinoline-based antioxidant is 0.1 to 0.95 parts by mass per 100 parts by mass of rubber component, excellent ozone resistance and high retention rate of elongation at break (EB) and tensile strength (TB) after aging are achieved even without using the antioxidant 6PPD. Furthermore, Comparative Example 3 shows that when the content of the quinoline-based antioxidant exceeds 0.95 parts by mass per 100 parts by mass of rubber component, the heat generation deteriorates.

Claims

1. Rubber components, The following general formula (1): 【Chemistry 1】 [In the formula, R １ and R ２ Each of these is an amine-based antioxidant represented by a monovalent saturated hydrocarbon group, It contains a quinoline-based anti-aging agent, The content of the amine-based antioxidant is 0.1 to 3.04 parts by mass per 100 parts by mass of the rubber component. A rubber composition for tires, characterized in that the amount of the quinoline-based antioxidant is 0.1 to 0.85 parts by mass per 100 parts by mass of the rubber component.

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

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

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

5. The tire rubber composition according to claim 1, further comprising wax, wherein the amount of wax is 0.1 to 5 parts by mass per 100 parts by mass of the rubber component.

6. A tire characterized by comprising a rubber member made of the tire rubber composition described in claim 1.

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