Tire rubber composition and tire

Abstract

The present invention addresses the problem of providing a tire rubber composition with which it is possible to suppress the occurrence of cracks while also achieving better tire fuel efficiency and wear resistance. As a means for solving said problem, this tire rubber composition is characterized by including a rubber component (A) and an anti-aging agent (B), wherein the rubber component (A) includes a copolymer (A1) of cyclopentene and a norbornene-based compound, which has a specific structure, and a modified polymer (A2), and the anti-aging agent (B) includes a triphenylamine-based anti-aging agent (B1) represented by a specific structural formula.

Description

Rubber composition for tires and tires

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

[0002] In connection with the recent trend toward global carbon dioxide emission regulations accompanying growing interest in environmental issues, there is an increasing demand for improved fuel economy in automobiles. To meet such demands, tire performance is also required to improve fuel economy (i.e., reduce rolling resistance). Furthermore, from the viewpoint of tire economics, in the development of rubber compositions for tires, it is also required to improve wear resistance in addition to fuel economy.

[0003] However, since fuel economy and abrasion resistance are generally in a trade-off relationship, it is difficult to achieve both. For example, a known method for improving abrasion resistance is to increase the amount of filler blended, but increasing the amount of filler blended results in a problem that the dispersion state of the filler deteriorates, resulting in a deterioration of fuel economy.

[0004] In response to this, Patent Documents 1 and 2 listed below disclose rubber compounds for passenger car tires and rubber compounds for heavy-duty truck and bus tires, each containing a specific long-chain branched cyclopentene ring-opening rubber (LCB-CPR), and these rubber compounds are said to be effective in reducing the rolling resistance of tires, improving wet skid resistance, and improving abrasion resistance.

[0005] 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 3 listed 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.

[0006] International Publication No. 2021 / 178233 International Publication No. 2021 / 178235 International Publication No. 2018 / 056384

[0007] However, after investigations by the present inventors, it was found that even with the techniques described in Patent Documents 1 and 2, it is difficult to achieve both low fuel consumption and wear resistance in a tire, and that there is still room for improvement.

[0008] Furthermore, N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (antioxidant 6PPD) used in the above-mentioned Patent Document 3 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 or barely use the antioxidant 6PPD in the rubber that constitutes the tire surface, the inventors' investigations have revealed that when the antioxidant 6PPD is not used or barely used, the ozone resistance of the rubber that constitutes the tire surface decreases, making it more susceptible to cracking.

[0009] Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional technology and to provide a rubber composition for a tire that can suppress the occurrence of cracks while achieving both low fuel consumption and high wear resistance for the tire.A further object of the present invention is to provide a tire that suppresses the occurrence of cracks while achieving both low fuel consumption and high wear resistance.

[0010] The rubber composition for a tire and the tire of the present invention that solve the above problems are summarized as follows.

[0011] [1] A rubber composition comprising a rubber component (A) and an antioxidant (B), wherein the rubber component (A) is a rubber component containing cyclopentene and a compound represented by the following general formula (1): [In the formula, R １１ ~R １４ each independently represents a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a substituent containing a halogen atom, a silicon atom, an oxygen atom, or a nitrogen atom; R １２ and R １３may be bonded to each other to form a ring, and m1 is an integer of 0 to 2.], and a modified polymer (A2), wherein the antioxidant (B) is a compound represented by the following general formula (2): [In the formula, R ２１ and R ２２ each independently represents a linear or branched alkyl group having 1 to 12 carbon atoms or a cycloalkyl group having 5 to 8 carbon atoms; R ２３ represents hydrogen, a linear or branched alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, -NH-R ２３１ , or -O-R ２３２ where R ２３１ and R ２３２ and each independently represent a linear or branched alkyl group having 1 to 12 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms.].

[0012] [2] The rubber composition for tires according to [1], wherein the norbornene-based compound represented by the general formula (1) is 2-norbornene and / or dicyclopentadiene.

[0013] [3] The rubber composition for a tire according to [1] or [2], wherein the content of the copolymer (A1) of cyclopentene and a norbornene-based compound is 20 to 90 parts by mass per 100 parts by mass of the rubber component (A).

[0014] [4] The rubber composition for a tire according to any one of [1] to [3], wherein the copolymer (A1) of cyclopentene and a norbornene-based compound has a content of cyclopentene-derived structural units of 20 to 75 mass%.

[0015] [5] The rubber composition for a tire according to [2], wherein the copolymer (A1) of cyclopentene and a norbornene-based compound has a content of structural units derived from 2-norbornene of 10 to 60 mass %.

[0016] [6] The rubber composition for a tire according to [2] or [5], wherein the copolymer (A1) of cyclopentene and a norbornene-based compound has a content of structural units derived from dicyclopentadiene of 10 to 60 mass%.

[0017] [7] The rubber composition for a tire according to any one of [1] to [6], wherein the modified polymer (A2) is a modified butadiene rubber or a modified styrene-butadiene rubber having a nitrogen-containing functional group.

[0018] [8] The rubber composition for a tire according to any one of [1] to [7], wherein a mass ratio (B / A1C) of the antioxidant (B) to the structural unit (A1C) derived from cyclopentene in the copolymer (A1) is 0.006 to 0.5.

[0019] [9] The rubber composition for a tire according to [2] or [5], wherein a mass ratio (B / A1N) of the antioxidant (B) to the structural unit (A1N) derived from 2-norbornene in the copolymer (A1) is 0.008 to 1.

[0020]

[10] The rubber composition for a tire according to [2] or [6], wherein a mass ratio (B / A1D) of the antioxidant (B) to the structural unit (A1D) derived from dicyclopentadiene in the copolymer (A1) is 0.008 to 1.

[0021]

[11] R in the above general formula (2) ２１ and R ２２ is an alkyl group selected from the group consisting of an isopropyl group, a 1,3-dimethylbutyl group, a 2-octyl group, and a 1,4-dimethylpentyl group.

[0022]

[12] R in the above general formula (2) ２１ and R ２２ The rubber composition for a tire according to any one of [1] to

[11] , wherein the number of carbon atoms is 2 to 8.

[0023]

[13] The rubber composition for a tire according to any one of [1] to

[12] , wherein the content of the antioxidant (B) is 0.5 to 10 parts by mass per 100 parts by mass of the rubber component (A), the antioxidant (B) further contains a quinoline-based antioxidant (B2), and a proportion of the quinoline-based antioxidant (B2) in the antioxidant (B) is 5 to 50% by mass.

[0024]

[14] The antioxidant (B) further comprises a compound represented by the following general formula (3): [In the formula, R ３１ and R ３２ are each independently a monovalent saturated hydrocarbon group.], and a proportion of the amine-based antioxidant (B3) in the antioxidant (B) is 0.1 to 80 mass %.

[0025]

[15] The antioxidant (B) further comprises a compound represented by the following general formula (4): [In the formula, R ４１ and R ４２ represents a phenyl group, and m4 represents an integer of 7 or greater.], and a proportion of the amine-based antioxidant (B4) in the antioxidant (B) is 0.1 to 80 mass %.

[0026]

[16] The rubber composition for a tire according to any one of [1] to

[15] , which is for use in a tire tread.

[0027]

[17] A tire comprising the rubber composition for a tire according to any one of [1] to

[15] .

[0028] According to the present invention, it is possible to provide a rubber composition for a tire that can suppress the occurrence of cracks while achieving both fuel economy and wear resistance of the tire. Also, according to the present invention, it is possible to provide a tire that suppresses the occurrence of cracks while achieving both fuel economy and wear resistance.

[0029] 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.

[0030] <Definitions> The compounds described herein may be derived in whole or in part from fossil resources, from biological resources such as plant resources, from recycled resources such as used tires, or from a mixture of two or more of fossil resources, biological resources, and recycled resources.

[0031] <Rubber composition for tire> The rubber composition for tire of this embodiment includes a rubber component (A) and an antioxidant (B). In the rubber composition for tire of this embodiment, the rubber component (A) contains cyclopentene and a compound represented by the following general formula (1): [In the formula, R １１ ~R １４ each independently represents a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a substituent containing a halogen atom, a silicon atom, an oxygen atom, or a nitrogen atom; R １２ and R １３ may be bonded to each other to form a ring, and m1 is an integer of 0 to 2.] and a modified polymer (A2) (also simply referred to as a "modified polymer"), [In the formula, R ２１ and R ２２ each independently represents a linear or branched alkyl group having 1 to 12 carbon atoms or a cycloalkyl group having 5 to 8 carbon atoms; R ２３ represents hydrogen, a linear or branched alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, -NH-R ２３１ , or -O-R ２３２ where R ２３１ and R ２３２ and each independently represent a linear or branched alkyl group having 1 to 12 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms.

[0032] In the rubber composition for tires of this embodiment, the copolymer of cyclopentene and a norbornene-based compound is characterized by having crosslinking points and by entanglement of polymer chains. Generally, when a filler is compounded with a rubber component, a reinforcing layer composed of the filler and the rubber component is formed around the filler, and this reinforcing layer contributes to improving the reinforcement properties of the rubber composition, thereby improving abrasion resistance, etc. In contrast, in the rubber composition for tires of this embodiment, since the rubber component (A) contains the copolymer (A1) of cyclopentene and a norbornene-based compound, the reinforcing layer formed around the filler is specifically increased by the entanglement of the polymer chains, thereby sufficiently improving abrasion resistance. Furthermore, in the rubber composition for tires of this embodiment, the reinforcing layer is developed by the entanglement of the polymer chains, thereby reducing hysteresis loss and improving fuel economy. Furthermore, in the rubber composition for tires of this embodiment, the rubber component (A) contains a modified polymer (A2), which has high affinity with fillers and can improve the dispersibility of the fillers, thereby improving the fuel economy and wear resistance of the rubber composition. Furthermore, the rubber composition for tires of this embodiment contains the triphenylamine-based antioxidant (B1) represented by the above general formula (2), thereby ensuring sufficient ozone resistance and suppressing the occurrence of cracks. Therefore, when the rubber composition for tires of this embodiment is applied to tires, it is possible to suppress the occurrence of cracks while achieving both fuel economy and wear resistance of the tires.

[0033] - Rubber Component (A) - The rubber composition for a tire of this embodiment includes a rubber component (A), which provides rubber elasticity to the composition. The rubber component (A) of the rubber composition for a tire of this embodiment includes a copolymer (A1) of cyclopentene and a norbornene-based compound represented by the above general formula (1), a modified polymer (A2), and may further include another rubber (A3).

[0034] --Copolymer (A1) of Cyclopentene and Norbornene-Based Compound-- The copolymer (A1) of cyclopentene and a norbornene-based compound contains a structural unit derived from cyclopentene and a structural unit derived from a norbornene-based compound represented by the above general formula (1). In a preferred embodiment, the copolymer (A1) of cyclopentene and a norbornene-based compound is a ring-opening copolymer, and in particular, a cyclopentene ring-opening copolymer.

[0035] In the above general formula (1), R １１ ~R １４ each independently represents a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a substituent containing a halogen atom, a silicon atom, an oxygen atom, or a nitrogen atom; R １２ and R １３ may be bonded to each other to form a ring, and m1 is an integer of 0 to 2. Here, examples of the hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, neopentyl, hexyl, and octyl groups; alkenyl groups such as vinyl, allyl, 2-pentenyl, 3-pentenyl, and 4-methyl-3-pentenyl groups; aryl groups such as phenyl, tolyl, 2,6-dimethylphenyl, 2,6-diisopropylphenyl, and naphthyl groups; and aralkyl groups such as benzyl and phenethyl groups.

[0036] Examples of the norbornene compounds represented by the general formula (1) include 2-norbornene, 5-methyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene, 5-hexyl-2-norbornene, 5-decyl-2-norbornene, 5-cyclohexyl-2-norbornene, 5-cyclopentyl-2-norbornene, 5-ethylidene-2-norbornene, 5-vinyl-2-norbornene, 5-propenyl-2-norbornene, 5-cyclohexenyl-2-norbornene, 5-cyclopentenyl-2-norbornene, 5-phenyl-2-norbornene, tetracyclo[9.2.1.0] ２，１０ .0 ３，８]tetradeca-3,5,7,12-tetraene (also called "1,4-methano-1,4,4a,9a-tetrahydro-9H-fluorene"), tetracyclo[10.2.1.0 ２，１１ .0 ４，９ ]pentadeca-4,6,8,13-tetraene (also called "1,4-methano-1,4,4a,9,9a,10-hexahydroanthracene"), dicyclopentadiene, methyldicyclopentadiene, dihydrodicyclopentadiene ("tricyclo[5.2.1.0 ２，６ Bicyclo[2.2.1]hept-2-enes, such as unsubstituted or hydrocarbon-substituted bicyclo[2.2.1]hept-2-enes, such as tetracyclo[6.2.1.1]dec-8-enes; ３，６ .0 ２，７ ] dodec-4-ene, 9-methyltetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, 9-ethyltetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, 9-cyclohexyltetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, 9-cyclopentyltetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, 9-methylenetetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, 9-ethylidenetetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, 9-vinyltetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, 9-propenyltetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, 9-cyclohexenyltetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, 9-cyclopentenyltetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, 9-phenyltetracyclo[6.2.1.1 ３，６ .0 ２，７] tetracyclo[6.2.1.1] dodec-4-ene and the like, which are unsubstituted or have hydrocarbon substituents; ３，６ .0 ２，７ ] dodec-4-enes; bicyclo[2.2.1]hept-2-enes having an alkoxycarbonyl group such as methyl 5-norbornene-2-carboxylate, ethyl 5-norbornene-2-carboxylate, methyl 2-methyl-5-norbornene-2-carboxylate, and ethyl 2-methyl-5-norbornene-2-carboxylate; tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-9-ene-4-carboxylate methyl, 4-methyltetracyclo[6.2.1.1 ３，６ .0 ２，７ ] tetracyclo[6.2.1.1] having an alkoxycarbonyl group, such as methyl dodec-9-ene-4-carboxylate ３，６ .0 ２，７ ] dodec-4-enes; bicyclo[2.2.1]hept-2-enes having a hydroxycarbonyl group or an acid anhydride group, such as 5-norbornene-2-carboxylic acid, 5-norbornene-2,3-dicarboxylic acid, and 5-norbornene-2,3-dicarboxylic acid anhydride; tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-9-ene-4-carboxylic acid, tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-9-ene-4,5-dicarboxylic acid, tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-9-ene-4,5-dicarboxylic anhydride, or other tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-enes; bicyclo[2.2.1]hept-2-enes having a hydroxyl group such as 5-hydroxy-2-norbornene, 5-hydroxymethyl-2-norbornene, 5,6-di(hydroxymethyl)-2-norbornene, 5,5-di(hydroxymethyl)-2-norbornene, 5-(2-hydroxyethoxycarbonyl)-2-norbornene, and 5-methyl-5-(2-hydroxyethoxycarbonyl)-2-norbornene; tetracyclo[6.2.1.1 ３，６.0 ２，７ ] dodec-9-ene-4-methanol, tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-9-en-4-ol and other hydroxyl group-containing tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-enes; bicyclo[2.2.1]hept-2-enes having a hydrocarbonyl group such as 5-norbornene-2-carbaldehyde; tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-9-ene-4-carbaldehyde, and the like. ３，６ .0 ２，７ ] dodec-4-enes; bicyclo[2.2.1]hept-2-enes having an alkoxycarbonyl group and a hydroxycarbonyl group, such as 3-methoxycarbonyl-5-norbornene-2-carboxylic acid; bicyclo[2.2.1]hept-2-enes having a carbonyloxy group, such as 5-norbornen-2-yl acetate, 2-methyl-5-norbornen-2-yl acetate, 5-norbornen-2-yl acrylate, and 5-norbornen-2-yl methacrylate; 9-tetracyclo[6.2.1.1] acetate ３，６ .0 ２，７ ] dodec-4-enyl acrylate, 9-tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-enyl, methacrylic acid 9-tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] tetracyclo[6.2.1.1] having a carbonyloxy group such as dodec-4-enyl ３，６ .0 ２，７ ] dodec-4-enes; bicyclo[2.2.1]hept-2-enes having a functional group containing a nitrogen atom, such as 5-norbornene-2-carbonitrile, 5-norbornene-2-carboxamide, and 5-norbornene-2,3-dicarboxylic acid imide; tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-9-ene-4-carbonitrile, tetracyclo[6.2.1.1 ３，６ .0 ２，７] dodec-9-ene-4-carboxamide, tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-9-ene-4,5-dicarboxylic acid imide, or the like. ３，６ .0 ２，７ ] dodec-4-enes; bicyclo[2.2.1]hept-2-enes having a halogen atom such as 5-chloro-2-norbornene; 9-chlorotetracyclo[6.2.1.1 ３，６ .0 ２，７ ] tetracyclo[6.2.1.1] dodec-4-ene having a halogen atom, ３，６ .0 ２，７ ] dodec-4-enes; bicyclo[2.2.1]hept-2-enes having a functional group containing a silicon atom, such as 5-trimethoxysilyl-2-norbornene and 5-triethoxysilyl-2-norbornene; 4-trimethoxysilyltetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-9-ene, 4-triethoxysilyltetracyclo[6.2.1.1 ３，６ .0 ２，７ ] tetracyclo[6.2.1.1] having a functional group containing a silicon atom, such as dodec-9-ene ３，６ .0 ２，７ ] dodec-4-enes; etc. The norbornene-based compounds may be used singly or in combination of two or more.

[0037] The norbornene-based compound represented by the general formula (1) is preferably one in which m1 is 0 or 1, more preferably one in which m1 is 0. １１ ~R １４ may be the same or different.

[0038] Among the norbornene compounds represented by the general formula (1), from the viewpoint of fuel economy and wear resistance of the rubber composition, R １１ ~R １４is preferably a hydrogen atom, a chain hydrocarbon group having 1 to 20 carbon atoms, or a substituent containing a halogen atom, a silicon atom, an oxygen atom, or a nitrogen atom. １１ ~R １４ are not particularly limited as long as they are groups that do not bond to each other and do not form a ring, and may be the same or different. R １１ ~R １４ is preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. In this case, m1 is preferably 0 or 1, and more preferably 0. R in the above general formula (1) １１ ~R １４ However, as the norbornene-based compound having a substituent containing a hydrogen atom, a chain hydrocarbon group having 1 to 20 carbon atoms, or a halogen atom, a silicon atom, an oxygen atom, or a nitrogen atom, unsubstituted or hydrocarbon-substituted bicyclo[2.2.1]hept-2-enes are preferred, and among these, 2-norbornene is particularly preferred.

[0039] Furthermore, as the norbornene-based compound represented by the general formula (1), R １２ and R １３ Also preferred are compounds in which R and R are bonded to each other to form a ring. １２ and R １３ Specific examples of the ring structure formed by bonding together include a cyclopentane ring, a cyclopentene ring, a cyclohexane ring, a cyclohexene ring, a benzene ring, etc., which may form a polycyclic structure and may further have a substituent. Among these, a cyclopentane ring, a cyclopentene ring, and a benzene ring are preferred, and a compound having a single cyclopentene ring or a polycyclic structure of a cyclopentane ring and a benzene ring is particularly preferred. １２ , R １３ Other than R １１ , R １４ may be the same or different, and are preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. In this case, m1 is preferably 0. １２ and R １３As the norbornene-based compound in which the above are bonded to each other to form a ring, unsubstituted or hydrocarbon-substituted bicyclo[2.2.1]hept-2-enes are preferred, and among these, dicyclopentadiene is particularly preferred.

[0040] The copolymer (A1) of cyclopentene and a norbornene compound preferably contains cyclopentene-derived structural units in an amount of 20 to 75 mass%, more preferably 25 to 70 mass%, even more preferably 30 to 65 mass%, and particularly preferably 35 to 60 mass%, based on the total repeating structural units of the copolymer (A1). By controlling the content of cyclopentene-derived structural units in the copolymer (A1) to fall within the range of 20 to 75 mass%, the fuel economy and wear resistance of a rubber composition containing the copolymer (A1) can be further improved.

[0041] The copolymer (A1) of cyclopentene and a norbornene compound preferably contains structural units derived from the norbornene compound represented by the general formula (1) in an amount of 10 to 80 mass%, more preferably 20 to 70 mass%, even more preferably 25 to 65 mass%, and particularly preferably 40 to 65 mass%, based on the total repeating structural units of the copolymer (A1). By controlling the content of structural units derived from the norbornene compound represented by the general formula (1) in the copolymer (A1) to fall within the range of 10 to 80 mass%, the fuel economy and wear resistance of a rubber composition containing the copolymer (A1) can be further improved.

[0042] In the copolymer (A1) of cyclopentene and a norbornene-based compound, the norbornene-based compound represented by the general formula (1) is preferably 2-norbornene and / or dicyclopentadiene. Since 2-norbornene and dicyclopentadiene are readily available, copolymers of cyclopentene and 2-norbornene and / or dicyclopentadiene are also readily available. Therefore, rubber compositions for tires containing copolymers of cyclopentene and 2-norbornene and / or dicyclopentadiene are advantageous in terms of cost.

[0043] When 2-norbornene is used as the norbornene compound represented by the general formula (1), the copolymer (A1) of cyclopentene and a norbornene compound preferably contains 10 to 60 mass% of structural units derived from 2-norbornene, and more preferably 20 to 60 mass%, of all repeating structural units in the copolymer (A1). By controlling the content of structural units derived from 2-norbornene in the copolymer (A1) to fall within the range of 10 to 60 mass%, the fuel economy and wear resistance of a rubber composition containing the copolymer (A1) can be further improved.

[0044] When dicyclopentadiene is used as the norbornene compound represented by the general formula (1), the copolymer (A1) of cyclopentene and a norbornene compound preferably contains 10 to 60 mass% of dicyclopentadiene-derived structural units, more preferably 20 to 50 mass%, of all repeating structural units in the copolymer (A1). By controlling the content of dicyclopentadiene-derived structural units in the copolymer (A1) to fall within the range of 10 to 60 mass%, the fuel economy and wear resistance of a rubber composition containing the copolymer (A1) can be further improved.

[0045] In one embodiment, the copolymer (A1) of cyclopentene and a norbornene-based compound may be a terpolymer of cyclopentene (CP), 2-norbornene (NB), and dicyclopentadiene (DCPD). The terpolymer of cyclopentene, 2-norbornene, and dicyclopentadiene is highly effective in improving the fuel economy of the rubber composition.

[0046] The copolymer (A1) of cyclopentene and a norbornene-based compound may be obtained by copolymerizing, in addition to cyclopentene and the norbornene-based compound represented by the general formula (1), other monomers copolymerizable therewith. Examples of such other monomers include cyclic monoolefins such as cyclopropene, cyclobutene, methylcyclopentene, cyclohexene, methylcyclohexene, cycloheptene, and cyclooctene; cyclic diolefins such as cyclohexadiene, methylcyclohexadiene, cyclooctadiene, and methylcyclooctadiene; and polycyclic cycloolefins having an aromatic ring such as phenylcyclooctene, 5-phenyl-1,5-cyclooctadiene, and phenylcyclopentene. The content of structural units derived from other monomers in the copolymer (A1) of cyclopentene and a norbornene-based compound is preferably 40% by mass or less, more preferably 30% by mass or less, based on the total repeating structural units of the copolymer (A1). It is particularly preferred that the copolymer (A1) is substantially free of structural units derived from other monomers.

[0047] The copolymer (A1) of cyclopentene and a norbornene-based compound preferably has a weight-average molecular weight (Mw) of 200,000 to 1,000,000, more preferably 200,000 to 800,000, even more preferably 200,000 to 700,000, and particularly preferably 200,000 to 600,000. A copolymer (A1) having a weight-average molecular weight (Mw) in the range of 200,000 to 1,000,000 is easy to produce and has good processability (workability). Furthermore, by setting the weight-average molecular weight (Mw) of the copolymer (A1) in the range of 200,000 to 1,000,000, the fuel economy and wear resistance of a rubber composition containing the copolymer (A1) can be further improved. The copolymer (A1) of cyclopentene and a norbornene compound preferably has a ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw / Mn, also referred to as "molecular weight distribution") of 1.0 to 5.0, more preferably 1.5 to 2.9, even more preferably 1.5 to 2.5, and particularly preferably 1.5 to 2.3. The weight average molecular weight (Mw) and number average molecular weight (Mn) of the copolymer (A1) are values ​​measured by gel permeation chromatography (GPC) in terms of polystyrene.

[0048] The copolymer (A1) of cyclopentene and a norbornene-based compound preferably has a cis / trans ratio of 0 / 100 to 60 / 40, more preferably 5 / 95 to 55 / 45, even more preferably 10 / 90 to 50 / 50, and particularly preferably 15 / 85 to 39 / 61. The cis / trans ratio refers to the ratio of cis-structures to trans-structures of double bonds present in the repeating units constituting the copolymer (A1) of cyclopentene and a norbornene-based compound (cis / trans ratio). By setting the cis / trans ratio of the copolymer (A1) within the above range, the fuel economy and wear resistance of a rubber composition containing the copolymer (A1) can be further improved.

[0049] The copolymer (A1) of cyclopentene and a norbornene-based compound preferably has a glass transition temperature (Tg) of -80°C to 10°C, more preferably -75°C to 0°C, and even more preferably -70°C to -10°C. By adjusting the glass transition temperature (Tg) of the copolymer (A1) within the above range, the fuel economy and abrasion resistance of a rubber composition containing the copolymer (A1) can be further improved. The glass transition temperature of the copolymer (A1) can be controlled, for example, by adjusting the type and amount of the norbornene-based compound used.

[0050] The copolymer (A1) of cyclopentene and a norbornene compound may have a modifying group at the polymer chain end. The presence of such a terminal modifying group can further enhance the affinity for silica and the like, thereby improving the dispersibility of silica and the like in the rubber composition, and as a result, the processability (workability), fuel economy, and abrasion resistance of the rubber composition can be further improved. The modifying group introduced into the polymer chain end of the copolymer (A1) is not particularly limited, but is preferably a modifying group containing an atom selected from the group consisting of atoms in Group 15 of the periodic table, atoms in Group 16 of the periodic table, and silicon atoms. From the viewpoint of enhancing affinity for silica and the like, the modifying group for forming the terminal modifying group is more preferably a modifying group containing an atom selected from the group consisting of nitrogen, oxygen, phosphorus, sulfur, and silicon atoms, and among these, a modifying group containing an atom selected from the group consisting of nitrogen, oxygen, and silicon atoms is even more preferred.

[0051] Examples of modifying groups containing nitrogen atoms include amino groups, pyridyl groups, imino groups, amide groups, nitro groups, urethane bond groups, and hydrocarbon groups containing any of these groups. Examples of modifying groups containing oxygen atoms include hydroxyl groups, carboxylic acid groups, ether groups, ester groups, carbonyl groups, aldehyde groups, epoxy groups, and hydrocarbon groups containing any of these groups. Examples of modifying groups containing silicon atoms include alkylsilyl groups, oxysilyl groups, and hydrocarbon groups containing any of these groups. Examples of modifying groups containing phosphorus atoms include phosphate groups, phosphino groups, and hydrocarbon groups containing any of these groups. Examples of modifying groups containing sulfur atoms include sulfonyl groups, thiol groups, thioether groups, and hydrocarbon groups containing any of these groups. The modifying group may also be a modifying group containing multiple of the above groups. Among these, from the viewpoint of further improving the processability (workability), fuel economy, and abrasion resistance of the rubber composition, an amino group, a pyridyl group, an imino group, an amide group, a hydroxyl group, a carboxylic acid group, an aldehyde group, an epoxy group, an oxysilyl group, or a hydrocarbon group containing any of these groups is preferred, and from the viewpoint of affinity for silica, etc., an oxysilyl group is particularly preferred. Here, the oxysilyl group refers to a group having a silicon-oxygen bond.

[0052] Examples of the oxysilyl group include an alkoxysilyl group, an aryloxysilyl group, an acyloxy group, an alkylsiloxysilyl group, and an arylsiloxysilyl group.Other examples include a hydroxysilyl group obtained by hydrolyzing an alkoxysilyl group, an aryloxysilyl group, or an acyloxy group.Among these, an alkoxysilyl group is preferred from the viewpoint of affinity with silica.The alkoxysilyl group is a group in which one or more alkoxy groups are bonded to a silicon atom, and specific examples thereof include a trimethoxysilyl group, a dimethoxymethylsilyl group, a methoxydimethylsilyl group, a methoxydichlorosilyl group, a triethoxysilyl group, a diethoxymethylsilyl group, an ethoxydimethylsilyl group, a dimethoxyethoxysilyl group, a methoxydiethoxysilyl group, and a tripropoxysilyl group.

[0053] The introduction rate of the modified group at the polymer chain end of the copolymer (A1) of cyclopentene and norbornene compound is not particularly limited, but the percentage value of the number of copolymer chain ends into which the modified group is introduced / the total number of copolymer chain ends is preferably 10% or more, more preferably 20% or more, even more preferably 30% or more, and particularly preferably 40% or more.The higher the introduction rate of the terminal modified group, the higher the affinity for silica and the like, so it is preferable.In addition, the method for measuring the introduction rate of the modified group at the polymer chain end is not particularly limited, but the case of introducing an oxysilyl group as the terminal modified group is exemplified as follows: １ It can be determined from the peak area ratio corresponding to the oxysilyl group determined by H-NMR spectrum measurement and the number average molecular weight (Mn) determined by gel permeation chromatography (GPC).

[0054] The copolymer (A1) of cyclopentene and a norbornene-based compound has a Mooney viscosity (ML １＋４ , 100°C) is preferably 20 to 150, more preferably 22 to 120, and particularly preferably 25 to 90.

[0055] The method for producing the copolymer (A1) of cyclopentene and a norbornene-based compound is not particularly limited, and examples thereof include a method in which cyclopentene and a norbornene-based compound represented by the general formula (1) are copolymerized in the presence of a ring-opening polymerization catalyst.

[0056] The ring-opening polymerization catalyst is not particularly limited as long as it can ring-open copolymerize cyclopentene with the norbornene-based compound represented by the general formula (1), but a ruthenium carbene complex or a halogen atom-containing Group 6 transition metal compound of the periodic table (hereinafter also referred to as "Group 6 transition metal compound of the periodic table") is preferred. These ring-opening polymerization catalysts may be used alone or in combination of two or more.

[0057] Examples of the ruthenium carbene complex include bis(tricyclohexylphosphine)benzylideneruthenium dichloride, bis(triphenylphosphine)-3,3-diphenylpropenylideneruthenium dichloride, bis(tricyclohexylphosphine)t-butylvinylideneruthenium dichloride, dichloro-(3-phenyl-1H-inden-1-ylidene)bis(tricyclohexylphosphine)ruthenium, bis(1,3-diisopropylimidazolin-2-ylidene)benzylideneruthenium dichloride, and bis(1,3-dicyclohexylimidazolin-2-ylidene)benzylideneruthenium dichloride. (1,3-dimesitylimidazolin-2-ylidene)benzylideneruthenium dichloride, (1,3-dimesitylimidazolin-2-ylidene)(tricyclohexylphosphine)benzylideneruthenium dichloride, (1,3-dimesitylimidazolin-2-ylidene)(tricyclohexylphosphine)benzylideneruthenium dichloride, (1,3-dimesitylimidazolidin-2-ylidene)(tricyclohexylphosphine)benzylideneruthenium dichloride, bis(tricyclohexylphosphine)ethoxymethylideneruthenium dichloride, (1,3-dimesitylimidazolidin-2-ylidene)(tricyclohexylphosphine)ethoxymethylideneruthenium dichloride, and the like.

[0058] The Group 6 transition metal compound of the periodic table is a compound having a Group 6 transition metal atom of the periodic table (long period periodic table, the same applies hereinafter), specifically a compound having a chromium atom, a molybdenum atom, or a tungsten atom, with a compound having a molybdenum atom or a compound having a tungsten atom being preferred, and a compound having a tungsten atom being more preferred in terms of high solubility in cyclopentene. Specific examples of the Group 6 transition metal compound of the periodic table include molybdenum compounds such as molybdenum pentachloride, molybdenum oxotetrachloride, and molybdenum(phenylimido)tetrachloride; and tungsten compounds such as tungsten hexachloride, tungsten oxotetrachloride, tungsten(phenylimido)tetrachloride, monocatecholatetungsten tetrachloride, bis(3,5-ditertiarybutyl)catecholatetungsten dichloride, and bis(2-chloroetherate)tetrachloride.

[0059] The amount of the ring-opening polymerization catalyst used, in terms of the molar ratio of (ring-opening polymerization catalyst:monomer used in copolymerization), is usually in the range of 1:500 to 1:2,000,000, preferably 1:700 to 1:1,500,000, and more preferably 1:1,000 to 1:1,000,000. When the Group 6 transition metal compound of the periodic table is used, the amount of the Group 6 transition metal compound used, in terms of the molar ratio of "Group 6 transition metal atom in the ring-opening polymerization catalyst:monomer used in ring-opening polymerization," is preferably in the range of 1:100 to 1:200,000, more preferably 1:200 to 1:150,000, and even more preferably 1:500 to 1:100,000.

[0060] When the above-mentioned transition metal compound of Group 6 of the periodic table is used as the ring-opening polymerization catalyst, it is preferable to use it in combination with an organoaluminum compound represented by the following general formula (5). The organoaluminum compound acts as a ring-opening polymerization catalyst together with the above-mentioned transition metal compound of Group 6 of the periodic table. (R ５１ ) ３－ｘ Al (OR ５２ ) ｘ ... (5) In the above general formula (5), R ５１ and R ５２ are each independently a hydrocarbon group having 1 to 20 carbon atoms, preferably a hydrocarbon group having 1 to 10 carbon atoms, and x is 0<x<3.

[0061] In the above general formula (5), R ５１ and R ５２ Examples of the alkyl group include alkyl groups such as methyl group, ethyl group, isopropyl group, n-propyl group, isobutyl group, n-butyl group, t-butyl group, n-hexyl group, cyclohexyl group, n-octyl group, and n-decyl group; and aryl groups such as phenyl group, 4-methylphenyl group, 2,6-dimethylphenyl group, 2,6-diisopropylphenyl group, and naphthyl group.

[0062] In the general formula (5), x is 0<x<3. That is, in the general formula (5), R ５１ and OR ５２The composition ratio of x to x can take any value within the ranges of 0<3-x<3 and 0<x<3, respectively. However, from the viewpoint of increasing the polymerization activity, x is preferably 0.5<x<1.5.

[0063] The organoaluminum compound represented by the general formula (5) can be synthesized, for example, by reacting trialkylaluminum with an alcohol, as shown in the following reaction formula: (R ５１ ) ３ Al + xR ５２ OH → (R ５１ ) ３－ｘ Al (OR ５２ ) ｘ + (R ５２ ) ｘ H

[0064] As shown in the above reaction formula, x in the general formula (5) can be arbitrarily controlled by specifying the reaction ratio of the corresponding trialkylaluminum and alcohol.

[0065] The amount of the organoaluminum compound used varies depending on the type of organoaluminum compound used, but is preferably 0.1 to 100 times by mole, more preferably 0.2 to 50 times by mole, and even more preferably 0.5 to 20 times by mole, relative to the Group 6 transition metal atoms constituting the Group 6 transition metal compound. If the amount of the organoaluminum compound used is too small, the polymerization activity may be insufficient, whereas if it is too large, side reactions tend to occur more easily during ring-opening polymerization.

[0066] The polymerization reaction may be carried out in a solventless state or in a solution. When copolymerization is carried out in a solution, the solvent used is not particularly limited as long as it is inert to the polymerization reaction and can dissolve the cyclopentene used in the copolymerization, the norbornene-based compound represented by the general formula (1), the polymerization catalyst, and the like. However, it is preferable to use a hydrocarbon solvent or a halogen-based solvent. Examples of the hydrocarbon solvent include aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; aliphatic hydrocarbons such as hexane, n-heptane, and n-octane; and alicyclic hydrocarbons such as cyclohexane, cyclopentane, and methylcyclohexane. Examples of the halogen-based solvent include haloalkanes such as dichloromethane and chloroform; and aromatic halogens such as chlorobenzene and dichlorobenzene. These solvents may be used alone or in combination of two or more.

[0067] When copolymerizing cyclopentene with a norbornene-based compound represented by the general formula (1), an olefin compound or a diolefin compound may be added to the polymerization reaction system as a molecular weight modifier, if necessary, to adjust the molecular weight of the resulting copolymer (A1). The olefin compound is not particularly limited as long as it is an organic compound having an ethylenically unsaturated bond, and examples thereof include α-olefins such as 1-butene, 1-pentene, 1-hexene, and 1-octene; styrenes such as styrene and vinyltoluene; halogen-containing vinyl compounds such as allyl chloride; alkenyl alcohols such as allyl alcohol and 5-hexenol; silicon-containing vinyl compounds such as allyltrimethoxysilane, allyltriethoxysilane, allyltrichlorosilane, and styryltrimethoxysilane; and disubstituted olefins such as 2-butene and 3-hexene. Examples of the diolefin compound include non-conjugated diolefins such as 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 1,6-heptadiene, 2-methyl-1,4-pentadiene, 2,5-dimethyl-1,5-hexadiene, etc. The amount of the olefin compound or diolefin compound used as a molecular weight modifier may be appropriately selected depending on the molecular weight of the copolymer (A1) to be produced, and is typically in the range of 1 / 100 to 1 / 100,000, preferably 1 / 200 to 1 / 50,000, and more preferably 1 / 500 to 1 / 10,000, in terms of molar ratio relative to the monomers used in copolymerization.

[0068] Furthermore, when the copolymer (A1) of cyclopentene and a norbornene-based compound is intended to have a modifying group at the polymer chain end, it is preferable to use a modifying group-containing olefinically unsaturated hydrocarbon compound as the molecular weight modifier instead of the above-mentioned olefin compound or diolefin compound. By using a modifying group-containing olefinically unsaturated hydrocarbon compound, the modifying group can be suitably introduced at the polymer chain end of the copolymer (A1) obtained by copolymerization. The modifying group-containing olefinically unsaturated hydrocarbon compound is not particularly limited as long as it has a modifying group and one metathesis-reactive olefinic carbon-carbon double bond. For example, when it is desired to introduce an oxysilyl group at the polymer chain end of the copolymer, an oxysilyl group-containing olefinically unsaturated hydrocarbon can be present in the polymerization reaction system.

[0069] Examples of the oxysilyl group-containing olefinically unsaturated hydrocarbon include those which introduce a modifying group into only one end (one end) of the polymer chain of the copolymer (A1), such as alkoxysilane compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, allylmethoxydimethylsilane, allyltriethoxysilane, allylethoxydimethylsilane, styryltrimethoxysilane, styryltriethoxysilane, styrylethyltriethoxysilane, allyltriethoxysilylmethyl ether, and allyltriethoxysilylmethylethylamine; vinyltriphenoxysilane, allyltriphenoxysilane, aryloxysilane compounds such as allylphenoxydimethylsilane; acyloxysilane compounds such as vinyltriacetoxysilane, allyltriacetoxysilane, allyldiacetoxymethylsilane, and allylacetoxydimethylsilane; alkylsiloxysilane compounds such as allyltris(trimethylsiloxy)silane; arylsiloxysilane compounds such as allyltris(triphenylsiloxy)silane; and polysiloxane compounds such as 1-allylheptamethyltrisiloxane, 1-allylnonamethyltetrasiloxane, 1-allylnonamethylcyclopentasiloxane, and 1-allylundecamethylcyclohexasiloxane. Examples of compounds for introducing modifying groups into both ends (both ends) of the polymer chain of the copolymer (A1) include alkoxysilane compounds such as bis(trimethoxysilyl)ethylene, bis(triethoxysilyl)ethylene, 2-butene-1,4-di(trimethoxysilane), 2-butene-1,4-di(triethoxysilane), and 1,4-di(trimethoxysilylmethoxy)-2-butene; aryloxysilane compounds such as 2-butene-1,4-di(triphenoxysilane); acyloxysilane compounds such as 2-butene-1,4-di(triacetoxysilane); alkylsiloxysilane compounds such as 2-butene-1,4-di[tris(trimethylsiloxy)silane]; arylsiloxysilane compounds such as 2-butene-1,4-di[tris(triphenylsiloxy)silane]; polysiloxane compounds such as 2-butene-1,4-di(heptamethyltrisiloxane) and 2-butene-1,4-di(undecamethylcyclohexasiloxane); and the like.

[0070] The modifying group-containing olefinically unsaturated hydrocarbon compound functions as a molecular weight modifier in addition to the function of introducing a modifying group into the polymer chain terminal of the copolymer (A1). Therefore, the amount of the modifying group-containing olefinically unsaturated hydrocarbon compound used may be appropriately selected depending on the molecular weight of the copolymer (A1) to be produced, and is usually in the range of 1 / 100 to 1 / 100,000, preferably 1 / 200 to 1 / 50,000, and more preferably 1 / 500 to 1 / 10,000, in terms of molar ratio relative to the monomers used in the copolymerization.

[0071] The polymerization reaction temperature is not particularly limited, but is preferably −100° C. or higher, more preferably −50° C. or higher, even more preferably 0° C. or higher, and particularly preferably 20° C. or higher. The upper limit of the polymerization reaction temperature is not particularly limited, but is preferably less than 120° C., more preferably less than 100° C., even more preferably less than 90° C., and particularly preferably less than 80° C. The polymerization reaction time is not particularly limited, but is preferably 1 minute to 72 hours, and more preferably 10 minutes to 20 hours.

[0072] If desired, a stabilizer such as a phenol-based stabilizer, a phosphorus-based stabilizer, or a sulfur-based stabilizer may be added to the copolymer (A1) obtained by the polymerization reaction. The amount of stabilizer added may be determined appropriately depending on the type of stabilizer. Furthermore, if desired, an extender oil may be blended into the copolymer (A1). When the copolymer (A1) is obtained as a polymerization solution, a known recovery method may be used to recover the copolymer (A1) from the polymerization solution. For example, a method may be used in which the solvent is separated by steam stripping or the like, the solid is filtered off, and then the solid is dried to obtain the solid copolymer (A1).

[0073] The content of the copolymer (A1) of cyclopentene and a norbornene-based compound is preferably 20 to 90 parts by mass, and more preferably 30 to 85 parts by mass, per 100 parts by mass of the rubber component (A). When the content of the copolymer (A1) of cyclopentene and a norbornene-based compound is in the range of 20 to 90 parts by mass per 100 parts by mass of the rubber component (A), the balance between fuel economy and abrasion resistance of the rubber composition is further improved.

[0074] --Modified Polymer (A2)-- The rubber component (A) contains a modified polymer (modified polymer) (A2). The modified polymer (A2) has high affinity with fillers and can improve the dispersibility of the fillers, thereby improving the fuel economy and wear resistance of the rubber composition. In this specification, the "modified polymer" excludes the above-mentioned copolymer (A1) of cyclopentene and a norbornene-based compound represented by the general formula (1). That is, the rubber component (A) of the rubber composition for tires of this embodiment contains the above-mentioned copolymer (A1) of cyclopentene and a norbornene-based compound and a modified polymer (A2) other than the copolymer (A1).

[0075] The modified functional group in the modified polymer (A2) can be, for example, a nitrogen-containing functional group, a silicon-containing functional group, a tin-containing functional group, an oxygen-containing functional group, etc., and among these, a nitrogen-containing functional group is preferred.When the modified polymer (A2) has a nitrogen-containing functional group, its affinity with the filler is further increased, and the dispersibility of the filler can be further improved, so that the fuel economy, abrasion resistance and processability of the rubber composition can be further improved.

[0076] The nitrogen atom-containing functional group is preferably selected from the following: a monovalent hydrocarbon group having a straight-chain, branched, alicyclic, or aromatic ring and having 1 to 30 carbon atoms, and having a functional group selected from the group consisting of a primary amino group, a primary amino group protected with a hydrolyzable protecting group, an onium salt residue of a primary amine, an isocyanate group, a thioisocyanate group, an imine group, an imine residue, an amide group, a secondary amino group protected with a hydrolyzable protecting group, a cyclic secondary amino group, an onium salt residue of a cyclic secondary amine, an acyclic secondary amino group, an onium salt residue of an acyclic secondary amine, an isocyanuric acid triester residue, a cyclic tertiary amino group, an acyclic tertiary amino group, a nitrile group, a pyridine residue, an onium salt residue of a cyclic tertiary amine, and an onium salt residue of an acyclic tertiary amine, or a monovalent hydrocarbon group having a straight-chain, branched, alicyclic, or aromatic ring and having 1 to 30 carbon atoms, which may contain at least one heteroatom selected from an oxygen atom, a sulfur atom, and a phosphorus atom.

[0077] The modified polymer (A2) may be a polymer obtained by using a conjugated diene compound, or a conjugated diene compound and an aromatic vinyl compound as a monomer, and modifying the molecular terminals and / or main chain of a polymer or copolymer of the conjugated diene compound, or a copolymer of a conjugated diene compound and an aromatic vinyl compound, with a modifying agent; or a polymer obtained by using a conjugated diene compound, or a conjugated diene compound and an aromatic vinyl compound as monomers, and polymerizing or copolymerizing these monomers using a polymerization initiator having a modifying functional group.

[0078] Regarding the monomers used in the synthesis of the modified polymer (A2), examples of conjugated diene compounds include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1,3-butadiene, and 1,3-hexadiene. Examples of aromatic vinyl compounds include styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, 4-cyclohexylstyrene, and 2,4,6-trimethylstyrene.

[0079] Examples of the modified polymer (A2) include modified synthetic isoprene rubber (IR), modified butadiene rubber (BR), modified styrene-butadiene rubber (SBR), and modified styrene-isoprene rubber (SIR). Among these, modified butadiene rubber (BR) and modified styrene-butadiene rubber (SBR) are preferred, with modified butadiene rubber (BR) being particularly preferred. Modified butadiene rubber (BR) has a low glass transition temperature (Tg), and by combining it with the above-mentioned copolymer of cyclopentene and a norbornene compound, the fuel economy and wear resistance of the rubber composition can be further improved. In addition, modified styrene-butadiene rubber (SBR) has a high glass transition temperature (Tg), excellent processability, and also has the effect of suppressing uneven wear of the rubber composition.

[0080] Furthermore, as the modified polymer (A2), modified butadiene rubber and modified styrene-butadiene rubber having a nitrogen-containing functional group are particularly preferred. When the modified polymer (A2) is a modified butadiene rubber or modified styrene-butadiene rubber having a nitrogen-containing functional group, affinity with the filler is further increased, and the dispersibility of the filler can be further improved, thereby further improving the fuel economy and abrasion resistance of the rubber composition.

[0081] The modifying agent is preferably a hydrocarbyloxysilane compound, and the hydrocarbyloxysilane compound is preferably a compound represented by the following general formula (6): ６１ ａ -Si-(OR ６２ ) ４－ａ ... (6)

[0082] In general formula (6), R ６１ and R ６２ each independently represents a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, a is an integer of 0 to 2, and OR ６２ If there are multiple, each OR ６２ may be the same or different, and the molecule does not contain any active protons.

[0083] The hydrocarbyloxysilane compound is also preferably an aminoalkoxysilane compound represented by the following general formula (7).

[0084] In the general formula (7), n1+n2+n3+n4=4 (wherein n2 is an integer of 1 to 4, and n1, n3, and n4 are integers of 0 to 3). １ is at least one functional group selected from a saturated cyclic tertiary amine compound residue, an unsaturated cyclic tertiary amine compound residue, a ketimine residue, a nitrile group, a (thio)isocyanate group, an isocyanuric acid trihydrocarbyl ester group, a pyridine group, a (thio)ketone group, an amide group, and a primary or secondary amino group having a hydrolyzable group. １ may be the same or different, and A１ may be a divalent group that bonds with Si to form a cyclic structure. ７１ represents a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and when n1 is 2 or more, they may be the same or different. ７２ is a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, both of which may contain a nitrogen atom and / or a silicon atom. ７２ may be the same or different, or may be joined together to form a ring. ７３ represents a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, or a halogen atom, and when n3 is 2 or greater, may be the same or different. ７４ represents a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and may be the same or different when n4 is 2 or greater. As the hydrolyzable group in the primary or secondary amino group having a hydrolyzable group, a trimethylsilyl group or a tert-butyldimethylsilyl group is preferred, and a trimethylsilyl group is particularly preferred.

[0085] The aminoalkoxysilane compound represented by the above general formula (7) is preferably an aminoalkoxysilane compound represented by the following general formula (7-1):

[0086] In the general formula (7-1), p1+p2+p3=2 (wherein p2 is an integer of 1 or 2, and p1 and p3 are integers of 0 or 1). ２ is NRa (Ra is a monovalent hydrocarbon group, a hydrolyzable group, or a nitrogen-containing organic group). ７５ is a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ７６is a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, or a nitrogen-containing organic group, any of which may contain a nitrogen atom and / or a silicon atom. ７６ may be the same or different, or may be joined together to form a ring. ７７ R is a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, or a halogen atom. ７８ is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. As the hydrolyzable group, a trimethylsilyl group or a tert-butyldimethylsilyl group is preferred, and a trimethylsilyl group is particularly preferred.

[0087] The aminoalkoxysilane compound represented by the above general formula (7) is also preferably an aminoalkoxysilane compound represented by the following general formula (7-2) or (7-3).

[0088] In the general formula (7-2), q1+q2=3 (wherein q1 is an integer of 0 to 2, and q2 is an integer of 1 to 3). ８１ is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ８２ and R ８３ are each independently a hydrolyzable group, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ８４ are monovalent aliphatic or alicyclic hydrocarbon groups having 1 to 20 carbon atoms or monovalent aromatic hydrocarbon groups having 6 to 18 carbon atoms, and when q1 is 2, they may be the same or different. ８５represents a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and may be the same or different when q2 is 2 or greater. A specific example of the aminoalkoxysilane compound represented by general formula (7-2) is N,N-bis(trimethylsilyl)-3-[diethoxy(methyl)silyl]propylamine (also referred to as "N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane").

[0089]

[0090] In the general formula (7-3), r1+r2=3 (where r1 is an integer of 1 to 3, and r2 is an integer of 0 to 2). ８６ is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ８７ represents a dimethylaminomethyl group, a dimethylaminoethyl group, a diethylaminomethyl group, a diethylaminoethyl group, a methylsilyl(methyl)aminomethyl group, a methylsilyl(methyl)aminoethyl group, a methylsilyl(ethyl)aminomethyl group, a methylsilyl(ethyl)aminoethyl group, a dimethylsilylaminomethyl group, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and when r1 is 2 or more, they may be the same or different. R ８８ represents a hydrocarbyloxy group having 1 to 20 carbon atoms, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and may be the same or different when r2 is 2. A specific example of the aminoalkoxysilane compound represented by general formula (7-3) is N-(1,3-dimethylbutylidene)-3-triethoxysilyl-1-propanamine.

[0091] The aminoalkoxysilane compound represented by the above general formula (7) is also preferably an aminoalkoxysilane compound represented by the following general formula (7-4) or (7-5).

[0092] In general formula (7-4), R９０ is a trimethylsilyl group, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ９１ R is a hydrocarbyloxy group having 1 to 20 carbon atoms, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ９２ is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms, where TMS represents a trimethylsilyl group (the same applies hereinafter).

[0093]

[0094] In general formula (7-5), R ９３ and R ９４ are each independently a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ９５ is a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and each R ９５ may be the same or different.

[0095] The aminoalkoxysilane compound represented by the above general formula (7) is also preferably an aminoalkoxysilane compound represented by the following general formula (7-6) or (7-7).

[0096] In the general formula (7-6), s1+s2 is 3 (wherein s1 is an integer of 0 to 2, and s2 is an integer of 1 to 3). ９６ is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ９７ and R ９８ are each independently a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ９７ or R ９８ may be the same or different.

[0097]

[0098] In the general formula (7-7), X is a halogen atom. ９９ is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. １００ and R １０１ are each independently a hydrolyzable group, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, or R １００ and R １０１ are bonded to form a divalent organic group. １０２ and R １０３ are each independently a halogen atom, a hydrocarbyloxy group, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms. １００ and R １０１ As the hydrolyzable group, a hydrolyzable group is preferred, and as the hydrolyzable group, a trimethylsilyl group or a tert-butyldimethylsilyl group is preferred, and a trimethylsilyl group is particularly preferred.

[0099] The aminoalkoxysilane compound represented by the general formula (7) is also preferably an aminoalkoxysilane compound represented by the following general formula (7-8), the following general formula (7-9), the following general formula (7-10), or the following general formula (7-11).

[0100] In the general formulas (7-8) to (7-10), the symbols u and v are integers of 0 to 2 and satisfy u+v=2. １０４ ~R １４２ may be the same or different and are monovalent or divalent aliphatic or alicyclic hydrocarbon groups having 1 to 20 carbon atoms, or monovalent or divalent aromatic hydrocarbon groups having 6 to 18 carbon atoms. t1 and t2 in general formula (7-11) are integers of 0 to 5.

[0101] Among the compounds satisfying the general formula (7-8), the general formula (7-9), and the general formula (7-10), N1,N1,N7,N7-tetramethyl-4-((trimethoxysilyl)methyl)heptane-1,7-diamine, 2-((hexyl-dimethoxysilyl)methyl)-N1,N1,N3,N3-2-pentamethylpropane-1,3-diamine, N1-(3-(dimethylamino)propyl)-N3,N3-dimethyl-N1-(3-(trimethoxysilyl)propyl)propane-1,3-diamine, and 4-(3-(dimethylamino)propyl)-N1,N1,N7,N7-tetramethyl-4-((trimethoxysilyl)methyl)heptane-1,7-diamine are particularly preferred. Among the compounds satisfying general formula (7-11), N,N-dimethyl-2-(3-(dimethoxymethylsilyl)propoxy)ethanamine, N,N-bis(trimethylsilyl)-2-(3-(trimethoxysilyl)propoxy)ethanamine, N,N-dimethyl-2-(3-(trimethoxysilyl)propoxy)ethanamine, and N,N-dimethyl-3-(3-(trimethoxysilyl)propoxy)propan-1-amine are particularly preferable.

[0102] The hydrocarbyloxysilane compound is also preferably a compound represented by the following general formula (8).

[0103] In the above general formula (8), A ３is a monovalent group having at least one functional group selected from (thio)epoxy, (thio)isocyanate, (thio)ketone, (thio)aldehyde, imine, amide, isocyanuric acid trihydrocarbyl ester, (thio)carboxylic acid ester, metal salt of (thio)carboxylic acid, carboxylic acid anhydride, carboxylic acid halide, and carbonic acid dihydrocarbyl ester. Here, "(thio)epoxy" refers to epoxy and thioepoxy, "(thio)isocyanate" refers to isocyanate and thioisocyanate, "(thio)ketone" refers to ketone and thioketone, "(thio)aldehyde" refers to aldehyde and thioaldehyde, "(thio)carboxylic acid ester" refers to carboxylic acid ester and thiocarboxylic acid ester, and "metal salt of (thio)carboxylic acid" refers to metal salt of carboxylic acid and metal salt of thiocarboxylic acid. R １５１ R is a single bond or a divalent inert hydrocarbon group, and the divalent inert hydrocarbon group preferably has 1 to 20 carbon atoms. １５２ and R １５３ each independently represents a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, n is an integer of 0 to 2, R １５２ If there are multiple R １５２ may be the same or different, OR １５３ If there are multiple, multiple OR １５３ may be the same or different. The molecule of the hydrocarbyloxysilane compound represented by the general formula (8) does not contain an active proton or an onium salt.

[0104] In the general formula (8), A ３ Among the functional groups in R, imine includes ketimine, aldimine, and amidine, and (thio)carboxylic acid ester includes unsaturated carboxylic acid ester such as acrylate and methacrylate. In addition, examples of the metal in the metal salt of (thio)carboxylic acid include alkali metals, alkaline earth metals, Al, Sn, and Zn. １５１Among these, preferred divalent inert hydrocarbon groups are alkylene groups having 1 to 20 carbon atoms. The alkylene groups may be linear, branched, or cyclic, with linear groups being particularly preferred. Examples of linear alkylene groups include methylene, ethylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, octamethylene, decamethylene, and dodecamethylene. R １５２ and R １５３ Examples of the alkyl group include an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms, and an aralkyl group having 7 to 18 carbon atoms. Here, the alkyl group and the alkenyl group may be linear, branched, or cyclic, and examples thereof 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 pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a cyclopentyl group, a cyclohexyl group, a vinyl group, a propenyl group, an allyl group, a hexenyl group, an octenyl group, a cyclopentenyl group, and a cyclohexenyl group. The aryl group may have a substituent such as a lower alkyl group on the aromatic ring, and examples thereof include a phenyl group, a tolyl group, a xylyl group, and a naphthyl group. Furthermore, the aralkyl group may have a substituent such as a lower alkyl group on the aromatic ring, examples of which include a benzyl group, a phenethyl group, a naphthylmethyl group, etc. n is an integer of 0 to 2, preferably 0, and the molecule must be free of active protons and onium salts.

[0105] Examples of the hydrocarbyloxysilane compound represented by the general formula (8) include (thio)epoxy group-containing hydrocarbyloxysilane compounds such as 2-glycidoxyethyltrimethoxysilane, 2-glycidoxyethyltriethoxysilane, (2-glycidoxyethyl)methyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane (hereinafter also referred to as "GPMOS"), 3-glycidoxypropyltriethoxysilane, (3-glycidoxypropyl)methyldimethoxysilane, 2-(3,4-epoxysilane), Preferred examples of the silane include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl(methyl)dimethoxysilane, 2-(3,4-epoxycyclohexyl)trimethoxysilane, and compounds in which the epoxy groups are replaced with thioepoxy groups. Of these, 3-glycidoxypropyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)trimethoxysilane are particularly preferred. Furthermore, examples of the imine group-containing hydrocarbyloxycyanide compound include N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, N-(1-methylethylidene)-3-(triethoxysilyl)-1-propanamine, N-ethylidene-3-(triethoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-(triethoxysilyl)-1-propanamine, N-(4-N,N-dimethylaminobenzylidene)-3-(triethoxysilyl)-1-propanamine, N-(cyclohex ... Preferred examples of the triethoxysilyl compounds include N-(1-methylpropylidene)-3-(triethoxysilyl)-1-propanamine and trimethoxysilyl compounds, methyldiethoxysilyl compounds, ethyldiethoxysilyl compounds, methyldimethoxysilyl compounds, and ethyldimethoxysilyl compounds corresponding to these triethoxysilyl compounds. Of these, N-(1-methylpropylidene)-3-(triethoxysilyl)-1-propanamine and N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine are particularly preferred.

[0106] The modifying agent is preferably a coupling agent represented by the following general formula (9).

[0107] In the above general formula (9), R １６１ , R １６２ and R １６３ R each independently represents a single bond or an alkylene group having 1 to 20 carbon atoms. １６４ , R １６５ , R １６６ , R １６７ and R １６９ R each independently represents an alkyl group having 1 to 20 carbon atoms. １６８ and R １７１ R each independently represents an alkylene group having 1 to 20 carbon atoms. １７０ represents an alkyl group or a trialkylsilyl group having 1 to 20 carbon atoms, m represents an integer of 1 to 3, and p represents 1 or 2. R １６１ ~R １７１ When there are a plurality of m and p, each is independent, and each of i, j and k independently represents an integer of 0 to 6, provided that (i+j+k) is an integer of 3 to 10. ４ represents a hydrocarbon group having 1 to 20 carbon atoms, or an organic group having at least one atom selected from the group consisting of an oxygen atom, a nitrogen atom, a silicon atom, a sulfur atom, and a phosphorus atom, and having no active hydrogen. ４ The hydrocarbon group represented by includes saturated, unsaturated, aliphatic, and aromatic hydrocarbon groups. Examples of organic groups without active hydrogen include a hydroxyl group (—OH), a secondary amino group (>NH), a primary amino group (—NH ２ ), a functional group having an active hydrogen such as a sulfhydryl group (-SH), or an organic group not having such a functional group.

[0108] The coupling agent represented by the general formula (9) is preferably at least one selected from the group consisting of tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, and tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane.

[0109] As the modifying agent, a coupling agent represented by the following general formula (10) is also preferred: (R １７６ ) ｂ ZX ｃ ... (10)

[0110] In the above general formula (10), Z is tin or silicon, and X is chlorine or bromine. １７６ is selected from the group consisting of alkyl groups having 1 to 20 carbon atoms, cycloalkyl groups having 3 to 20 carbon atoms, aryl groups having 6 to 20 carbon atoms, and aralkyl groups having 7 to 20 carbon atoms, where R １７６ Specific examples of the alkyl group include a methyl group, an ethyl group, an n-butyl group, a neophyl group, a cyclohexyl group, an n-octyl group, and a 2-ethylhexyl group. b is an integer of 0 to 3, and c is an integer of 1 to 4, where b+c=4.

[0111] The coupling agent represented by the general formula (10) includes tin tetrachloride, (R １７６ ) SnCl ３ , (R １７６ ) ２ SnCl ２ , (R １７６ ) ３ SnCl, silicon tetrachloride, etc. are preferred, and among these, tin tetrachloride is particularly preferred.

[0112] The polymerization initiator having a modified functional group is preferably a lithium amide compound, such as lithium hexamethyleneimide, lithium pyrrolidide, lithium piperidide, lithium heptamethyleneimide, lithium dodecamethyleneimide, lithium dimethylamide, lithium diethylamide, lithium dibutylamide, lithium dipropylamide, lithium diheptylamide, lithium dihexylamide, lithium dioctylamide, lithium di-2-ethylhexylamide, lithium didecylamide, lithium-N-methylpiperazide, lithium ethylpropylamide, lithium ethylbutylamide, lithium ethylbenzylamide, and lithium methylphenethylamide.

[0113] The lithium amide compound may also be a compound represented by the formula: Li-AM [wherein AM is represented by the following formula (11)]: (In the formula, R １８１ and R １８２ are each independently an alkyl group, a cycloalkyl group, or an aralkyl group having 1 to 12 carbon atoms, or a substituted amino group represented by the following formula (12): (In the formula, R １８３ represents an alkylene group, a substituted alkylene group, an oxyalkylene group, or an N-alkylamino-alkylene group having 3 to 16 methylene groups. is a cyclic amino group represented by the formula (11). By using a lithium amide compound represented by the formula (12), a modified polymer having introduced therein at least one nitrogen-containing functional group selected from the group consisting of a substituted amino group represented by the formula (11) and a cyclic amino group represented by the formula (12) can be obtained.

[0114] In the above formula (11), R １８１ and R １８２ is an alkyl group, a cycloalkyl group or an aralkyl group having 1 to 12 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, a butyl group, an octyl group, a cyclohexyl group, a 3-phenyl-1-propyl group and an isobutyl group. 1８１ and R １８２ may be the same or different.

[0115] In the above formula (12), R１８３ is an alkylene group, a substituted alkylene group, an oxyalkylene group, or an N-alkylamino-alkylene group having 3 to 16 methylene groups. Here, the substituted alkylene group includes mono- to octa-substituted alkylene groups, and the substituents include linear or branched alkyl groups, cycloalkyl groups, bicycloalkyl groups, aryl groups, and aralkyl groups having 1 to 12 carbon atoms. １８３ Specifically, a trimethylene group, a tetramethylene group, a hexamethylene group, an oxydiethylene group, an N-alkylazadiethylene group, a dodecamethylene group, a hexadecamethylene group, and the like are preferred.

[0116] The lithium amide compound may be prepared in advance from a secondary amine and a lithium compound and used in the polymerization reaction, or may be generated in the polymerization system. Examples of the secondary amine include dimethylamine, diethylamine, dibutylamine, dioctylamine, dicyclohexylamine, diisobutylamine, and the like, as well as azacycloheptane (also referred to as "hexamethyleneimine (HMI)"), 2-(2-ethylhexyl)pyrrolidine, 3-(2-propyl)pyrrolidine, 3,5-bis(2-ethylhexyl)piperidine, 4-phenylpiperidine, 7-decyl-1-azacyclotridecane, 3,3-dimethyl-1-azacyclotetradecane, 4-dodecyl-1-azacyclooctane, 4-(2-phenylbutyl)-1-azacyclooctane, 3-ethyl-5-cyclohexyl-1-azacycloheptane, 4-hexyl-1-azacycloheptane, 9-methyl-1-azacyclopentane, 10-methyl-1-azacyclopentane, 11-methyl-1-azacyclopentane, 12-methyl-1-azacyclopentane, 13-methyl-1-azacyclopentane, 14-methyl-1-azacyclopentane, 15-methyl-1-azacyclopentane, 16-methyl-1-azacyclopentane, 17-methyl-1-azacyclopentane, 18-methyl-1-azacyclopentane, 19-methyl-1-azacyclopentane, 20-methyl-1-azacyclopentane, 21-methyl-1-azacyclopentane, 22-methyl-1-azacyclopentane, 23-methyl-1-azacyclopentane, 24-methyl-1-azacyclopentane, 25-methyl-1-azacyclopentane, 26-methyl-1-azacyclopentane, 27- -isoamyl-1-azacycloheptadecane, 2-methyl-1-azacycloheptadec-9-ene, 3-isobutyl-1-azacyclododecane, 2-methyl-7-tert-butyl-1-azacyclododecane, 5-nonyl-1-azacyclododecane, 8-(4'-methylphenyl)-5-pentyl-3-azabicyclo[5.4.0]undecane, 1-butyl-6-azabicyclo[3.2.1]octane, 8-ethyl-3-azabicyclo[3.2.1]octane, 1-propyl-3-azabicyclo[3.2.2]nonane, 3-(tert-butyl)-7-azabicyclo[4.3.0]nonane, 1,5,5-trimethyl-3-azabicyclo[4.4.0]decane and other cyclic amines. Furthermore, examples of the lithium compound that can be used include hydrocarbyl lithium such as ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-octyl lithium, n-decyl lithium, phenyl lithium, 2-naphthyl lithium, 2-butyl-phenyl lithium, 4-phenyl-butyl lithium, cyclohexyl lithium, cyclopentyl lithium, and a reaction product of diisopropenyl benzene with butyl lithium.

[0117] In the production of the modified polymer (A2), anionic polymerization using the polymerization initiator having the above-mentioned modifying functional group or the lithium compound (i.e., a polymerization initiator not having a modifying functional group) may be used, but the polymerization reaction mechanism is not limited thereto, and for example, coordination polymerization may be used. Here, when the modified polymer (A2) is produced by coordination polymerization, it is preferable to use a rare earth metal compound as the polymerization initiator, and it is more preferable to use the following components (a), (b), and (c) in combination.

[0118] The component (a) used in the coordination polymerization is selected from rare earth metal compounds and complex compounds of rare earth metal compounds and Lewis bases. Examples of rare earth metal compounds include carboxylates, alkoxides, β-diketone complexes, phosphates, and phosphites of rare earth elements. Examples of Lewis bases include acetylacetone, tetrahydrofuran, pyridine, N,N-dimethylformamide, thiophene, diphenyl ether, triethylamine, organic phosphorus compounds, and monohydric or dihydric alcohols. Preferred rare earth elements in the rare earth metal compounds are lanthanum, neodymium, praseodymium, samarium, and gadolinium, with neodymium being particularly preferred. Specific examples of component (a) include neodymium versatate, neodymium tri-2-ethylhexanoate and its complex compound with acetylacetone, neodymium trineodecanoate and its complex compound with acetylacetone, and neodymium tri-n-butoxide.

[0119] The component (b) used in the coordination polymerization is selected from organoaluminum compounds. Specific examples of the organoaluminum compound include trihydrocarbylaluminum compounds, hydrocarbylaluminum hydrides, and hydrocarbylaluminoxane compounds having a hydrocarbon group having 1 to 30 carbon atoms. Specific examples of the organoaluminum compound include trialkylaluminums, dialkylaluminum hydrides, alkylaluminum dihydrides, and alkylaluminoxanes. It is preferable to use aluminoxane in combination with another organoaluminum compound as the component (b).

[0120] The component (c) used in the coordination polymerization is selected from compounds having a hydrolyzable halogen or complex compounds of these with a Lewis base; organic halides having a tertiary alkyl halide, benzyl halide, or allyl halide; ionic compounds comprising a non-coordinating anion and a counter cation, etc. Specific examples of the component (c) include alkylaluminum dichlorides, dialkylaluminum chlorides, silicon tetrachloride, tin tetrachloride, complexes of zinc chloride with a Lewis base such as an alcohol, complexes of magnesium chloride with a Lewis base such as an alcohol, benzyl chloride, t-butyl chloride, benzyl bromide, t-butyl bromide, triphenylcarbonium tetrakis(pentafluorophenyl)borate, etc.

[0121] The modified polymer (A2) may be reacted with a modifier such as a hydrocarbyloxysilane compound and then with a condensation accelerator containing a metal element, or at least one selected from the group consisting of an inorganic acid and a metal halide. By reacting the modified polymer (A2) with the condensation accelerator containing a metal element, or at least one selected from the group consisting of an inorganic acid and a metal halide, a modified polymer (A2) having a high Mooney viscosity and excellent shape stability can be produced.

[0122] As the condensation accelerator containing a metal element, it is preferable to use a metal compound containing at least one metal selected from metals in Groups 2 to 15 of the periodic table. Specific metal elements include titanium, zirconium, aluminum, bismuth, tin, etc. Furthermore, as the condensation accelerator containing a metal element, an alkoxide, carboxylate, or acetylacetonate complex salt of the above metal is preferable. Specifically, preferred examples of the condensation accelerator include tetrakis(2-ethyl-1,3-hexanediolato)titanium, tetrakis(2-ethylhexyloxy)titanium (hereinafter also referred to as "tetra 2-ethylhexyl titanate" or "EHOTi"), tetra(octanediolate)titanium, tris(2-ethylhexanoate)bismuth, tetra-n-propoxyzirconium, tetra-n-butoxyzirconium, bis(2-ethylhexanoate)zirconium oxide, bis(oleate)zirconium oxide, tri-i-propoxyaluminum, tri-sec-butoxyaluminum, tris(2-ethylhexanoate)aluminum, tris(stearate)aluminum, zirconium tetrakis(acetylacetonate), aluminum tris(acetylacetonate), bis(2-ethylhexanoate)tin, and di-n-octyltin bis(2-ethylhexyl maleate).

[0123] On the other hand, examples of the inorganic acid include hydrochloric acid, sulfuric acid, and phosphoric acid. Furthermore, as the metal halide, a metal halide containing at least one metal selected from Groups 2 to 15 of the periodic table can be suitably used. For example, a halide containing at least one metal atom selected from the group consisting of silicon, tin, aluminum, zinc, titanium, and zirconium is more preferred. Specifically, the metal halide is preferably trimethylsilyl chloride, dimethyldichlorosilane, methyltrichlorosilane, silicon tetrachloride, methyldichlorosilane, tin tetrachloride, diethylaluminum chloride, ethylaluminum sesquichloride, ethylaluminum dichloride, zinc chloride, titanium tetrachloride, titanocene dichloride, zirconium tetrachloride, or zirconocene dichloride. The reaction with the inorganic acid or metal halide is preferably carried out in the presence of water. The water may be used in the form of a pure substance, a solution such as an alcohol, or a micelle dispersion in a hydrocarbon solvent.

[0124] The modified polymer (A2) may be stabilized by reacting it with a modifying agent such as a hydrocarbyloxysilane compound and then reacting it with a carboxylic acid partial ester of a polyhydric alcohol. Here, the carboxylic acid partial ester of a polyhydric alcohol refers to an ester of a polyhydric alcohol and a carboxylic acid, which has one or more hydroxyl groups. Specifically, esters of sugars or modified sugars having 4 or more carbon atoms and fatty acids are preferably used. More preferred examples of this ester include (1) fatty acid partial esters of polyhydric alcohols, particularly partial esters (monoesters, diesters, or triesters) of saturated or unsaturated higher fatty acids having 10 to 20 carbon atoms and polyhydric alcohols, and (2) ester compounds in which 1 to 3 partial esters of polycarboxylic acids and higher alcohols are bonded to a polyhydric alcohol. The polyhydric alcohol used as a raw material for the partial ester is preferably a sugar having 5 or 6 carbon atoms and at least three hydroxyl groups (which may be hydrogenated or not), glycol, or polyhydroxy compound. The raw material fatty acid is preferably a saturated or unsaturated fatty acid having 10 to 20 carbon atoms, such as stearic acid, lauric acid, or palmitic acid. Among the fatty acid partial esters of the polyhydric alcohols, sorbitan fatty acid esters are preferred, and specific examples include sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, and sorbitan trioleate.

[0125] The content of the modified polymer (A2) is preferably 5 to 90 parts by mass, more preferably 10 to 80 parts by mass, and even more preferably 15 to 70 parts by mass, per 100 parts by mass of the rubber component (A). When the content of the modified polymer (A2) is 5 to 90 parts by mass or more per 100 parts by mass of the rubber component (A), the balance between fuel economy and wear resistance of the rubber composition is further improved.

[0126] -Other Rubber (A3)- The rubber component (A) may further contain another rubber (A3). Examples of such other rubber (A3) include natural rubber (NR), unmodified synthetic isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), butyl rubber (IIR), halogenated butyl rubber, ethylene-propylene rubber (EPR, EPDM), fluororubber, silicone rubber, and urethane rubber. The content of these other rubbers (A3) is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of the rubber component (A).

[0127] —Antiaging Agent (B)—The rubber composition for a tire of this embodiment contains an antioxidant (B), which has the effect of preventing aging of a tire using the rubber composition.

[0128] The content of the antioxidant (B) is preferably 0.5 to 10 parts by mass, more preferably 1 to 8 parts by mass, per 100 parts by mass of the rubber component (A). When the content of the antioxidant (B) is 0.5 parts by mass or more per 100 parts by mass of the rubber component (A), the ozone resistance of the rubber composition can be sufficiently ensured. Furthermore, when the content of the antioxidant (B) is 10 parts by mass or less per 100 parts by mass of the rubber component (A), adverse effects on rubber properties other than ozone resistance (such as heat buildup) are reduced, making the rubber composition suitable for use as a tire tread rubber.

[0129] The mass ratio (B / A1C) of the antioxidant (B) to the cyclopentene-derived structural unit (A1C) in the copolymer (A1) is preferably 0.006 to 0.5, more preferably 0.01 to 0.5. When the mass ratio (B / A1C) of the antioxidant (B) to the cyclopentene-derived structural unit (A1C) in the copolymer (A1) is 0.006 to 0.5, an excellent balance is achieved between the effect of improving the fuel economy and abrasion resistance of the rubber composition and the effect of suppressing crack generation.

[0130] The mass ratio (B / A1N) of the antioxidant (B) to the structural unit (A1N) derived from 2-norbornene in the copolymer (A1) is preferably 0.008 to 1, and more preferably 0.01 to 1. When the mass ratio (B / A1N) of the antioxidant (B) to the structural unit (A1N) derived from 2-norbornene in the copolymer (A1) is 0.008 to 1, an excellent balance is achieved between the effect of improving the fuel economy and abrasion resistance of the rubber composition and the effect of suppressing the occurrence of cracks.

[0131] The mass ratio (B / A1D) of the antioxidant (B) to the dicyclopentadiene-derived structural unit (A1D) in the copolymer (A1) is preferably 0.008 to 1, and more preferably 0.01 to 1. When the mass ratio (B / A1D) of the antioxidant (B) to the dicyclopentadiene-derived structural unit (A1D) in the copolymer (A1) is 0.008 to 1, an excellent balance is achieved between the effect of improving the fuel economy and abrasion resistance of the rubber composition and the effect of suppressing the occurrence of cracks.

[0132] --Triphenylamine-based antioxidant (B1) of formula (2)-- The antioxidant (B) is a triphenylamine-based antioxidant represented by the following general formula (2): [In the formula, R ２１ and R ２２ each independently represents a linear or branched alkyl group having 1 to 12 carbon atoms or a cycloalkyl group having 5 to 8 carbon atoms; R ２３ represents hydrogen, a linear or branched alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, -NH-R ２３１ , or -O-R ２３２ where R ２３１ and R ２３２each independently represent a linear or branched alkyl group having 1 to 12 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms. The triphenylamine-based antioxidant (B1) represented by general formula (2) has the effect of improving the ozone resistance of the rubber composition and can suppress the occurrence of cracks in tires using the rubber composition. Furthermore, the triphenylamine-based antioxidant (B1) represented by general formula (2) has a low environmental impact.

[0133] R in the above general formula (2) ２１ and R ２２ R each independently represents a linear or branched alkyl group having 1 to 12 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms. ２１ and R ２２ As the alkyl group, a linear or branched alkyl group having 2 to 8 carbon atoms or a cycloalkyl group having 5 to 8 carbon atoms is preferred.

[0134] R in the above general formula (2) ２３ represents hydrogen, a linear or branched alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, -NH-R ２３１ , or -O-R ２３２ where R ２３１ and R ２３２ R each independently represents a linear or branched alkyl group having 1 to 12 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms. ２３ is hydrogen, a linear or branched alkyl group having 1 to 10 carbon atoms, -NH-R ２３１ , and -O-R ２３２ is preferable. ２３１ As R, a linear or branched alkyl group having 2 to 8 carbon atoms and a cycloalkyl group having 5 to 8 carbon atoms are preferred. ２３２ As the alkyl group, a linear or branched alkyl group having 1 to 10 carbon atoms is preferred.

[0135] R ２１ , R ２２ and R ２３１With regard to the above, examples of the linear or branched alkyl group having 2 to 8 carbon atoms include an ethyl group, a propyl group (i.e., an n-propyl group, an isopropyl group), a butyl group (i.e., an n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group), a pentyl group, a hexyl group, a heptyl group, and an octyl group.

[0136] R ２３ and R ２３２ With regard to (1), examples of the linear or branched alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group (i.e., an n-propyl group, an isopropyl group), a butyl group (i.e., an n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group), a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, and a decyl group. Among these, a methyl group, an ethyl group, and a propyl group (i.e., an n-propyl group, an isopropyl group) are preferred, a methyl group and an ethyl group are more preferred, and a methyl group is particularly preferred.

[0137] Also, R ２１ , R ２２ , R ２３ , R ２３１ and R ２３２ Regarding the above, examples of the cycloalkyl group having 5 to 8 carbon atoms include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group, and among these, a cyclohexyl group is preferred.

[0138] The synthesis method of the triphenylamine-based antioxidant (B1) represented by the above general formula (2) is described in French Patent No. 1,354,536 and US Pat. No. 3,277,174. For example, (i) an aromatic amine compound such as aniline, p-toluidine, or p-anisidine is reacted with a halogenated nitrobenzene such as 4-fluoronitrobenzene or 4-chloronitrobenzene to obtain a dinitrotriphenylamine compound such as 4,4'-dinitrotriphenylamine, 4,4'-dinitro-4''-methyltriphenylamine, or 4,4'-dinitro-4''-methoxytriphenylamine, and the dinitrotriphenylamine compound is reduced to obtain a diaminotriphenylamine compound such as 4,4'-diaminotriphenylamine, 4,4'-diamino-4''-methyltriphenylamine, or 4,4'-diamino-4''-methoxytriphenylamine, and the diaminotriphenylamine compound is reacted with a ketone such as acetone, methyl isobutyl ketone, or 2-octanone, or (ii) tris(p-aminophenyl)amine is reacted with a ketone such as acetone, methyl isobutyl ketone, or 2-octanone, The triphenylamine antioxidant represented by the above general formula (2) can be synthesized.

[0139] R in the above general formula (2) ２１ and R ２２ is preferably an isopropyl group, a 1,3-dimethylbutyl group, a 2-octyl group, or a 1,4-dimethylpentyl group. ２１ and R ２２ A triphenylamine-based antioxidant in which R is an isopropyl group, a 1,3-dimethylbutyl group, a 2-octyl group, or a 1,4-dimethylpentyl group can further improve the ozone resistance of the rubber composition and can further suppress the occurrence of cracks in a tire to which the rubber composition is applied.

[0140] R in the above general formula (2) ２３ is preferably a hydrogen atom, an isopropylamino group, a 1,3-dimethylbutylamino group, a 1,4-dimethylpentylamino group, or a methoxy group. ２３A triphenylamine-based antioxidant in which R is hydrogen, an isopropylamino group, a 1,3-dimethylbutylamino group, a 1,4-dimethylpentylamino group, or a methoxy group can further improve the ozone resistance of the rubber composition and can further suppress the occurrence of cracks in a tire to which the rubber composition is applied.

[0141] R in the above general formula (2) ２１ and R ２２ Preferably, R in general formula (2) has 2 to 8 carbon atoms. ２１ and R ２２ The triphenylamine-based antioxidant having 2 to 8 carbon atoms can further improve the ozone resistance of the rubber composition and can further suppress the occurrence of cracks in a tire to which the rubber composition is applied.

[0142] The triphenylamine-based antioxidant (B1) is preferably a compound represented by the following general formula (2-1) or (2-2): [In the formula, R ２１ , R ２２ and R ２３１ each independently represents a linear or branched alkyl group having 1 to 12 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms.] [In the formula, R ２１ and R ２２ each independently represent a linear or branched alkyl group having 1 to 12 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms.] is preferred. The compound represented by general formula (2-1) or (2-2) can further improve the ozone resistance of the rubber composition, and can further suppress the occurrence of cracks in a tire to which the rubber composition is applied.

[0143] R in the above general formula (2-1) ２１ , R ２２ and R ２３１ , and R in the above general formula (2-2) ２１ and R ２２are each independently a linear or branched alkyl group having 1 to 12 carbon atoms or a cycloalkyl group having 5 to 8 carbon atoms, and are preferably a linear or branched alkyl group having 2 to 8 carbon atoms or a cycloalkyl group having 5 to 8 carbon atoms. Examples of the linear or branched alkyl group having 2 to 8 carbon atoms include an ethyl group, a propyl group (i.e., an n-propyl group, an isopropyl group), a butyl group (i.e., an n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group), a pentyl group, a hexyl group, a heptyl group, and an octyl group. Examples of the cycloalkyl group having 5 to 8 carbon atoms include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group, and among these, a cyclohexyl group is preferred.

[0144] R in the above general formula (2-1) ２１ , R ２２ and R ２３１ , and R in the above general formula (2-2) ２１ and R ２２ is preferably an isopropyl group, a 1,3-dimethylbutyl group, a 2-octyl group, or a 1,4-dimethylpentyl group. ２１ , R ２２ and R ２３１ is an isopropyl group, a 1,3-dimethylbutyl group, a 2-octyl group, or a 1,4-dimethylpentyl group, and a triphenylamine-based antioxidant represented by the general formula (2-2), ２１ and R ２２ A triphenylamine-based antioxidant in which R is an isopropyl group, a 1,3-dimethylbutyl group, a 2-octyl group, or a 1,4-dimethylpentyl group can further improve the ozone resistance of the rubber composition and can further suppress the occurrence of cracks in a tire to which the rubber composition is applied.

[0145] R in the above general formula (2-1) ２１ , R ２２ and R ２３１ , and R in the above general formula (2-2) ２１ and R ２２ Preferably, R in the general formula (2-1) has 2 to 8 carbon atoms. ２１ , R２２ and R ２３１ and a triphenylamine-based antioxidant having 2 to 8 carbon atoms, ２１ and R ２２ The triphenylamine-based antioxidant having 2 to 8 carbon atoms can further improve the ozone resistance of the rubber composition and can further suppress the occurrence of cracks in a tire to which the rubber composition is applied.

[0146] The triphenylamine-based antioxidant (B1) is preferably a compound represented by the following general formula (2-3): The compound represented by general formula (2-3) can also further improve the ozone resistance of the rubber composition, and can further suppress the occurrence of cracks in a tire to which the rubber composition is applied.

[0147] In the above general formula (2-3), R ２１１ , R ２１２ , R ２２１ and R ２２２ are each independently an alkyl group, provided that R ２１１ and R ２１２ The total number of carbon atoms in R is 2 to 11, preferably 2 to 7. ２２１ and R ２２２ The total number of carbon atoms in R in the general formula (2-3) is 2 to 11, and preferably 2 to 7. ２３ represents R in the general formula (2) ２３ and is synonymous with hydrogen, a linear or branched alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, -NH-R ２３１ , or -O-R ２３２ where R ２３１ and R ２３２ are each independently a linear or branched alkyl group having 1 to 12 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms. ２３ With respect to -NH-R ２３１ Examples of the group include —NH—CHR ２３１１ R ２３１２ is preferred, where R ２３１１ and R ２３１２are each independently an alkyl group, provided that R ２３１１ and R ２３１２ The total number of carbon atoms is 2 to 11, preferably 2 to 7.

[0148] The triphenylamine-based antioxidant (B1) is preferably a compound represented by the following general formula (2-1-1) or (2-2-1): In the above general formula (2-1-1), a compound represented by R ２１１ , R ２１２ , R ２２１ , R ２２２ , R ２３１１ and R ２３１２ are each independently an alkyl group, provided that R ２１１ and R ２１２ The total number of carbon atoms in R is 2 to 11, preferably 2 to 7. ２２１ and R ２２２ The total number of carbon atoms in R is 2 to 11, preferably 2 to 7. ２３１１ and R ２３１２ The total number of carbon atoms in R is 2 to 11, and preferably 2 to 7. ２１１ , R ２１２ , R ２２１ and R ２２２ are each independently an alkyl group, provided that R ２１１ and R ２１２ The total number of carbon atoms in R is 2 to 11, preferably 2 to 7. ２２１ and R ２２２ The total number of carbon atoms is 2 to 11, preferably 2 to 7.

[0149] Specific examples of the triphenylamine-based antiaging agent represented by the general formula (2) include 4,4'-bis(isopropylamino)triphenylamine, 4,4'-bis(1,3-dimethylbutylamino)triphenylamine, 4,4'-bis(2-octylamino)triphenylamine, 4,4'-bis(1,4-dimethylpentylamino)triphenylamine, 4,4'-bis(isopropylamino)-4''-methyltriphenylamine, 4,4'-bis(1,3-dimethylbutylamino)-4''-methyltriphenylamine, 4,4'-bis(2-octylamino)-4''-methyltriphenylamine, 4,4'-bis(1,4-dimethylpentylamino)-4''-methyltriphenylamine, Preferred are 4,4',4''-tris(isopropylamino)triphenylamine, 4,4',4''-tris(1,3-dimethylbutylamino)triphenylamine, 4,4',4''-tris(2-octylamino)triphenylamine, 4,4',4''-tris(1,4-dimethylpentylamino)triphenylamine, 4,4'-bis(isopropylamino)-4''-methoxytriphenylamine, 4,4'-bis(1,3-dimethylbutylamino)-4''-methoxytriphenylamine, 4,4'-bis(2-octylamino)-4''-methoxytriphenylamine, and 4,4'-bis(1,4-dimethylpentylamino)-4''-methoxytriphenylamine. These triphenylamine-based antioxidants (B1) may be used alone or in combination of two or more.

[0150] The proportion of the triphenylamine-based antioxidant (B1) represented by the general formula (2) in the antioxidant (B) is preferably 10 to 100 mass%, more preferably 20 to 100 mass%. When the proportion of the triphenylamine-based antioxidant (B1) represented by the general formula (2) in the antioxidant (B) is 10 to 100 mass%, the ozone resistance of the rubber composition can be further improved, and the occurrence of cracks in tires using the rubber composition can be further suppressed.

[0151] Quinoline-Based Antiaging Agent (B2) The antioxidant (B) preferably further contains a quinoline-based antioxidant (B2). The quinoline-based antioxidant (B2) is an antioxidant having a quinoline moiety or a derivative thereof (e.g., a dihydroquinoline moiety, a tetrahydroquinoline moiety, etc.). The quinoline-based antioxidant (B2) has the effect of improving the ozone resistance of the rubber composition, and a rubber composition containing both the triphenylamine-based antioxidant (B1) represented by the above general formula (2) and the quinoline-based antioxidant (B2) can further suppress the occurrence of cracks in tires.

[0152] The quinoline-based antioxidant (B2) preferably has a dihydroquinoline moiety, and more preferably has a 1,2-dihydroquinoline moiety. Specific examples of the quinoline-based antioxidant (B2) include a polymer of 2,2,4-trimethyl-1,2-dihydroquinoline (antiaging agent TMDQ) and 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline. The quinoline-based antioxidant (B2) preferably contains a polymer of 2,2,4-trimethyl-1,2-dihydroquinoline (antiaging agent TMDQ). Quinoline-based antioxidants (B2) 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. Therefore, a rubber composition containing a polymer of 2,2,4-trimethyl-1,2-dihydroquinoline can further suppress the occurrence of cracks in tires and is also less susceptible to discoloration. Examples of the polymer of 2,2,4-trimethyl-1,2-dihydroquinoline include a dimer, trimer, and tetramer of 2,2,4-trimethyl-1,2-dihydroquinoline.

[0153] The proportion of the quinoline-based antioxidant (B2) in the antioxidant (B) is preferably 5 to 50 mass%, more preferably 10 to 40 mass%. When the proportion of the quinoline-based antioxidant (B2) in the antioxidant (B) is 5 to 50 mass%, the ozone resistance of the rubber composition can be further improved, and the occurrence of cracks in tires using the rubber composition can be further suppressed.

[0154] --Amine-based antioxidant (B3) of formula (3)-- The antioxidant (B) can further be an amine-based antioxidant represented by the following general formula (3): [In the formula, R ３１ and R ３２ are each independently a monovalent saturated hydrocarbon group. It is preferable to include an amine-based antioxidant (B3) represented by the following general formula (3): The amine-based antioxidant (B3) represented by the following general formula (3) contains a phenylenediamine moiety, just like the general-purpose antioxidant 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 the phenylenediamine moiety. The amine-based antioxidant (B3) represented by the general formula (3) has the effect of improving the ozone resistance of the rubber composition.

[0155] In the above general formula (3), R ３１ and R ３２ are each independently a monovalent saturated hydrocarbon group. ３１ and R ３２ may be the same or different, but from the viewpoint of synthesis, they are preferably the same.

[0156] 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 further improves the ozone resistance of the rubber composition. ３１ and R ３２ 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.

[0157] 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. Of these, a cyclohexyl group is preferred.

[0158] Specific examples of the amine-based antioxidant (B3) represented by the general formula (3) 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 (antiaging agent CCPD) are preferred, with N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (antiaging agent 77PD) being particularly preferred. The amine-based antioxidant (B3) represented by the formula (3) may be used alone or in combination of two or more.

[0159] The proportion of the amine-based antioxidant (B3) represented by the general formula (3) in the antioxidant (B) is preferably 0.1 to 80 mass%, more preferably 1 to 70 mass%. When the proportion of the amine-based antioxidant (B3) represented by the formula (3) in the antioxidant (B) is 0.1 to 80 mass%, the ozone resistance of the rubber composition can be further improved, and the occurrence of cracks in tires using the rubber composition can be further suppressed.

[0160] --Amine-based antioxidant (B4) of formula (4)-- The antioxidant (B) can further be an amine-based antioxidant represented by the following general formula (4): [In the formula, R ４１ and R ４２ represents a phenyl group, and m4 represents an integer of 7 or more. The amine-based antioxidant (B4) represented by the above general formula (4) has a higher molecular weight than conventional antioxidants, and as shown in the above formula (4), it has a bridge moiety having a unique and relatively long chain length, i.e., "-NH-CH(CH ３ )-(CH ２ ) ｍ４ -CH(CH ３ )-NH-". It is believed that the high molecular weight and the presence of specific bridge moieties of the amine-based antiaging agent (B4) reduce the diffusion rate in the rubber composition, and migration to the rubber surface is further suppressed. Furthermore, the amine-based antiaging agent (B4) has a moiety composed of "-CH(CH ３ )-(CH ２ ) ｍ４ -CH(CH ３ One hydrogen atom is bonded to each of the two nitrogen atoms present at both ends of "(2-amino-2-methyl-2-methyl-2-propanol)-" (forming a so-called secondary amino group), and the presence of this bond in the structure represented by formula (4) is thought to contribute to the specific effect of improving ozone resistance (weather resistance).

[0161] In the above general formula (4), R ４１ and R ４２ is a phenyl group. ４１ and R ４２When is a phenyl group, the ozone resistance of the rubber composition can be further improved, and discoloration of the rubber composition can be more reliably prevented.

[0162] In the general formula (4), m4 is an integer of 7 or more, and from the viewpoint of improving the ozone resistance of the rubber composition and preventing discoloration, it is preferably an integer of 8 to 16, and more preferably an integer of 10 to 14.

[0163] Examples of the amine-based antioxidant (B4) of the above formula (4) include N,N'-bis(4-anilinophenyl)dodecane-2,11-diamine, N,N'-bis(4-anilinophenyl)tetradecane-2,13-diamine, N,N'-bis(4-anilinophenyl)hexadecane-2,15-diamine, N,N'-bis(4-anilinophenyl)octadecane-2,17-diamine, etc. Of these, N,N'-bis(4-anilinophenyl)tetradecane-2,13-diamine and N,N'-bis(4-anilinophenyl)octadecane-2,17-diamine are particularly preferred.

[0164] The proportion of the amine-based antioxidant (B4) represented by the general formula (4) in the antioxidant (B) is preferably 0.1 to 80 mass%, more preferably 1 to 70 mass%. When the proportion of the amine-based antioxidant (B4) represented by the formula (4) in the antioxidant (B) is 0.1 to 80 mass%, the ozone resistance of the rubber composition can be further improved, and the occurrence of cracks in tires using the rubber composition can be further suppressed.

[0165] --Other Antiaging Agents (B5)-- The rubber composition of this embodiment may or may not contain an antioxidant (B5) other than the triphenylamine-based antioxidant (B1) of formula (2), the quinoline-based antioxidant (B2), the amine-based antioxidant (B3) of formula (3), and the amine-based antioxidant (B4) of formula (4). Examples of the other antioxidant (B5) include N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) and N,N'-diphenyl-p-phenylenediamine (DPPD). However, it is preferable to exclude N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD). Commercially available antioxidants can be used, including those from Ouchi Shinko Chemical Industry Co., Ltd., Sumitomo Chemical Co., Ltd., Seiko Chemical Co., Ltd., and Flexis. These antioxidants (B5) may be used alone or in combination of two or more. The proportion of the other antioxidants (B5) in the antioxidant (B) is preferably 0 to 20% by mass, more preferably 0 to 10% by mass.

[0166] Filler (C) The rubber composition for a tire of this embodiment preferably contains a filler (C). By containing the filler (C), the reinforcement property of the rubber composition is improved. Examples of the filler (C) include carbon black, silica, clay, talc, calcium carbonate, and aluminum hydroxide. Among these, carbon black is preferred.

[0167] The content of the filler (C) is preferably in the range of 5 to 80 parts by mass per 100 parts by mass of the rubber component (A). When the content of the filler (C) is 5 parts by mass or more per 100 parts by mass of the rubber component (A), the abrasion resistance of the rubber composition is further improved, and when the content is 80 parts by mass or less, the fuel economy of the rubber composition is further improved. From the viewpoint of abrasion resistance, the content of the filler (C) is more preferably 10 parts by mass or more, and even more preferably 20 parts by mass or more, per 100 parts by mass of the rubber component (A). From the viewpoint of fuel economy, the content of the filler (C) is more preferably 70 parts by mass or less, and even more preferably 60 parts by mass or less.

[0168] --Carbon Black-- The filler (C) preferably contains carbon black. The carbon black reinforces the rubber composition and can improve the abrasion resistance of the rubber composition. As the carbon black, plant-derived carbon black and recycled carbon black (also called "recycled carbon black") are preferred. Examples of plant-derived carbon black include those derived from castor oil and pine oil. Recycled carbon black will be described in detail below.

[0169] From the viewpoint of further improving the abrasion resistance of the rubber composition and a tire using the same, the content of carbon black (total of recycled carbon black and carbon black other than recycled carbon black) 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 rubber component (A). Also, from the viewpoint of workability of the rubber composition, the content of carbon black in the rubber composition is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, and even more preferably 70 parts by mass or less, per 100 parts by mass of rubber component (A).

[0170] ---Recycled Carbon Black--- In this specification, "recycled carbon black" refers to carbon black recovered from recycled waste raw materials. Examples of such waste include waste rubber, used tires, and waste oil. Waste rubber refers to all discarded rubber, including not only that generated from rubber products but also unwanted scraps generated during the production or repair of rubber products. Examples of scraps include buffing powder and peeled rubber. Buffing powder is fine rubber generated during the buffing process, for example, in tire retreading, where the tread portion remaining on the base tire is scraped off. Peeled rubber is a long piece of rubber, e.g., 1 to 2 cm wide, peeled from the surface of a rubber product such as a tire. Peeled rubber is generated by scraping the surface of a rubber product such as a tire using a U- or V-shaped knife like a peeler. Furthermore, waste rubber is not limited to crosslinked rubber but also includes unvulcanized rubber. Rubber products include, for example, final products such as tires and rubber hoses, as well as rubber parts or components during the manufacturing process of final products. Used tires may be tires to be retreaded, or may be tires discarded for some reason, such as tires generated during tire replacement or scrapping, or ELTs (End-of-Life Tires) that have reached the end of their service life. Waste oils are not limited to those generated during the decomposition of plastics and rubber, but also include used oils discharged from industry, such as animal and vegetable oils, lubricating oils, insulating oils, and cutting oils. Among these, waste oils that contain no non-organic components, such as those derived from silicone rubber or polyvinyl chloride, are desirable. Furthermore, waste oils containing carbon black or rubber containing carbon black are desirable. "Recycled carbon black" differs from carbon black produced directly from hydrocarbons such as petroleum, natural gas, and coal, i.e., non-recycled carbon black. Note that "used" here refers not only to waste oils discarded after actual use, but also to waste oils that were produced but discarded without actually being used.

[0171] The recycled carbon black is preferably obtained by pyrolysis of a vulcanized rubber product containing carbon black. Recycled carbon black obtained by pyrolysis of a vulcanized rubber product containing carbon black is readily available because vulcanized rubber products containing carbon black are readily available and can be easily obtained by pyrolysis. Furthermore, the recycled carbon black is preferably obtained from the solid residue produced by the pyrolysis of the vulcanized rubber product containing carbon black. When a rubber product containing carbon black is pyrolyzed, a solid residue and a volatile component (oil) are obtained, and recycled carbon black can be recovered from either of them. When recovering carbon black from the volatile component, the oil component with a specific gravity suitable for producing carbon black can be recovered and used to produce carbon black using existing carbon black production methods (e.g., JP 2015-520259 A). Unlike carbon black recovered from solid residues, this method offers advantages such as no impurities and no mixing of different grades. In addition, in the production of environmentally friendly carbon black, various options are available, including oils obtained by recovering volatile components from rubber pyrolysis, as described above, as well as vegetable oils and oils derived from waste plastics. However, edible resources such as vegetable oils are needed for other uses, such as food, and there are challenges in securing sufficient quantities, as well as the environmental impact of expanding cultivated land. Furthermore, oils derived from waste plastics are also used for other purposes, such as horizontal plastic recycling, so supply issues are also a concern. On the other hand, using volatile components (oils) produced by the pyrolysis of vulcanized rubber products, particularly tires, allows for the continued use of existing materials due to the tire industry's ongoing system of using existing materials, thereby reducing the consumption of new materials in new tire production and contributing to a reduction in the industry's environmental impact. The grade of carbon black is not particularly limited, and examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762.

[0172] Solid residues obtained by pyrolysis of waste materials such as used rubber and used tires contain ash in addition to carbon black. The ash is derived from non-volatile components contained in the rubber and tires. Therefore, recycled carbon black obtained from the solid residues has a relatively low carbon black content. On the other hand, considering the various physical properties required for tires manufactured using recycled carbon black, the higher the carbon content of the recycled carbon black, the better. The carbon content of the recycled carbon black is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 87% by mass or more, and particularly preferably 89% by mass or more. Furthermore, the carbon content of the recycled carbon black is preferably 97% by mass or less. Note that the carbon content does not include adsorbed moisture.

[0173] Specific examples of the ash include zinc oxide, zinc sulfide, silica, iron compounds (iron oxide), calcium oxide, aluminum oxide, and magnesium oxide. In the case of recycled carbon black produced from solid residue obtained by pyrolysis of waste, a certain amount of ash remains even after various processes for removing the ash. In this embodiment, the recycled carbon black is allowed to contain ash. In one embodiment, the lower limit of the ash content of the recycled carbon black may be 0.5% by mass.

[0174] The recycled carbon black can also be obtained from a pyrolysis process of used pneumatic tires. For example, European Patent Application Publication No. 3,427,975, citing "Rubber Chemistry and Technology," Vol. 85, No. 3, pp. 408-449 (2012), particularly pp. 438, 440, and 442, describes that recycled carbon black can be obtained by pyrolysis of organic materials at 550-800°C in the absence of oxygen, or by vacuum pyrolysis at relatively low temperatures (paragraph

[0027] ). Carbon black obtained from such pyrolysis processes typically lacks functional groups on its surface, as mentioned in paragraph

[0004] of Japanese Patent Publication No. 6,856,781 (Comparison of the Surface Morphology and Chemistry of Pyrolytic Carbon Black and Commercially Available Carbon Black, Powder Technology 160 (2005) pp. 190-193).

[0175] The recycled carbon black may lack functional groups on its surface, or may be treated to include functional groups on its surface. The treatment to include functional groups on the surface of recycled carbon black can be carried out by conventional methods. For example, in European Patent Application Publication No. 3,173,251, carbon black obtained by a pyrolysis process is treated with potassium permanganate under acidic conditions to obtain carbon black containing hydroxyl and / or carboxyl groups on its surface. Furthermore, in Japanese Patent Publication No. 6,856,781, carbon black obtained by a pyrolysis process is treated with an amino acid compound containing at least one thiol or disulfide group to obtain surface-activated carbon black. The recycled carbon black according to this embodiment also includes carbon blacks treated to include functional groups on their surfaces.

[0176] Furthermore, examples of thermal decomposition of crosslinked rubber products (vulcanized rubber products) such as used tires include thermal decomposition methods at temperatures of 650° C. or higher.

[0177] The crosslinked rubber products used for the decomposition may be grouped by the type of rubber component previously compounded, and then the decomposition step may be performed for each group. Alternatively, the crosslinked rubber products may be grouped by the type of filler previously compounded (e.g., type of carbon black, type of silica, mixing ratio of carbon black and silica, etc.), and then the decomposition step may be performed for each group. Furthermore, the crosslinked rubber products may be grouped by both type of rubber component and type of filler, and then the decomposition step may be performed for each group. When the decomposition step is performed for each group in this way, recycled carbon black with more uniform physical properties can be obtained, and when the recycled carbon black is compounded again into a rubber component, a rubber composition with better performance can be obtained.

[0178] Furthermore, when the crosslinked rubber product used in the degradation is derived from tires, the tires may be grouped in advance by type (e.g., for passenger cars, for trucks and buses, for large vehicles such as off-road vehicles, for aircraft, for agricultural vehicles, etc.), and the degradation step may be carried out for each group. Alternatively, the tires may be grouped in advance by tire component (e.g., tread rubber, sidewall rubber, bead rubber, steel cord-coated rubber, organic fiber-coated rubber, pad rubber, cushion rubber, etc.), and the degradation step may be carried out for each group. Furthermore, the tires may be grouped both by type and by tire component, and the degradation step may be carried out for each group. When the degradation step is carried out for each group in this way, recycled carbon black with more uniform physical properties can be obtained, and therefore, when the recycled carbon black is blended again into a rubber component, a rubber composition with better performance can be obtained.

[0179] The recycled carbon black has a nitrogen adsorption specific surface area of ​​40 to 100 m as measured by the BET method. ２ / g, and 50 to 90m ２ / g, and more preferably 55 to 75m ２ In this specification, the nitrogen adsorption specific surface area of ​​recycled carbon black measured by the BET method is a statistical thickness specific surface area (STSA) determined in accordance with ASTM D6556.

[0180] The pH of the recycled carbon black is preferably 4 to 12, more preferably 5 to 11, and particularly preferably 6 to 10. In this specification, the pH of the recycled carbon black is determined in accordance with ASTM D1512.

[0181] The recycled carbon black preferably has a toluene color transmittance of 60% or more, more preferably 70% or more, and particularly preferably 80% or more. Herein, the toluene color transmittance of recycled carbon black is determined in accordance with ASTM D1618.

[0182] The recycled carbon black preferably has a heat loss of 3% by mass or less, more preferably 2.5% by mass or less, and particularly preferably 2% by mass or less at 125°C. Herein, the heat loss of recycled carbon black at 125°C is determined in accordance with ASTM D1509.

[0183] The recycled carbon black preferably has a sulfur content of 5% by mass or less, more preferably 3.5% by mass or less, and particularly preferably 3% by mass or less.

[0184] The recycled carbon black preferably has a 35 mesh sieve residue of 20 mass ppm or less, more preferably 15 mass ppm or less, and particularly preferably 10 mass ppm or less. Herein, the 35 mesh sieve residue of recycled carbon black is determined in accordance with ASTM D1514.

[0185] The recycled carbon black preferably has a 325 mesh (44 μm) sieve residue of 1000 mass ppm or less, more preferably 700 mass ppm or less, and particularly preferably 300 mass ppm or less. Herein, the 325 mesh (44 μm) sieve residue of the recycled carbon black is determined in accordance with ASTM D1514.

[0186] The recycled carbon black preferably has a pellet hardness of 100 cN or less, more preferably 90 cN or less, and particularly preferably 80 cN or less. Herein, the pellet hardness of recycled carbon black is determined in accordance with ASTM D5230.

[0187] The recycled carbon black preferably has a pellet fine powder content of 10% by mass or less, more preferably 7% by mass or less, and particularly preferably 5% by mass or less. Herein, the pellet fine powder content of recycled carbon black is determined in accordance with ASTM D1508.

[0188] The particle size (D97) of the recycled carbon black is preferably 25 μm or less, more preferably 15 μm or less, and particularly preferably 10 μm or less. Here, in this specification, the particle size (D97) of the recycled carbon black is determined using a laser diffraction particle size distribution analyzer, assuming a refractive index of 1.33 for water and a refractive index of 1.75 for the filler.

[0189] The recycled carbon black preferably contains particles of 5 μm or less in a proportion of 50% by volume or more, more preferably 70% by volume or more, and particularly preferably 80% by volume or more.

[0190] The recycled carbon black preferably has an ash content of 25% by mass or less, more preferably 20% by mass or less, and particularly preferably 15% by mass or less. When the ash content of the recycled carbon black is 25% by mass or less, the physical properties of the rubber product to which the rubber composition is applied can be improved. Herein, the ash content of the recycled carbon black is determined in accordance with ASTM D8474 and D1506.

[0191] The recycled carbon black preferably has an oil absorption number (OAN) of 70 to 120 mL / 100 g, more preferably 75 to 110 mL / 100 g, and particularly preferably 80 to 100 mL / 100 g. Herein, the OAN of recycled carbon black is determined in accordance with ASTM D2414.

[0192] The recycled carbon black preferably has an oil absorption (COAN) of a compressed sample of 50 to 110 mL / 100 g, more preferably 60 to 100 mL / 100 g, and particularly preferably 70 to 90 mL / 100 g. Herein, the COAN of the recycled carbon black is determined in accordance with ASTM D3493.

[0193] Commercially available recycled carbon black can be used. For example, Enrestec's product name "PB365" can be mentioned as such a commercially available product. PB365 is a recycled carbon black produced through the thermal decomposition of used tires, and has a nitrogen adsorption specific surface area of ​​73.6 m2 as measured by the BET method. ２ / g and contains about 17% by mass of ash.

[0194] The content of the recycled carbon black is preferably 1 to 100 parts by mass, more preferably 5 to 80 parts by mass, even more preferably 5 to 50 parts by mass, still more preferably 5 to 30 parts by mass, and particularly preferably 5 to 20 parts by mass, per 100 parts by mass of the rubber component (A). When the content of the recycled carbon black is 5 parts by mass or more per 100 parts by mass of the rubber component (A), the effect of improving the proportion of sustainable materials in rubber products to which the rubber composition is applied is significant, and when the content is 50 parts by mass or less, the fracture resistance of the rubber composition can be more reliably maintained.

[0195] The proportion of carbon black in the filler (C) is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and may be 100% by mass, from the viewpoint of the abrasion resistance of the rubber composition.

[0196] Others In addition to the rubber component (A), antioxidant (B), and filler (C) described above, the rubber composition for a tire of this embodiment may contain various components commonly used in the rubber industry, such as a silane coupling agent, hardened fatty acid, zinc oxide (zinc white), a tackifier, a vulcanization accelerator, and a vulcanizing agent, as needed, selected appropriately within the scope of the present invention. Commercially available products can be suitably used as these compounding ingredients.

[0197] Examples of the hardened fatty acid include stearic acid, etc. The content of the hardened fatty acid is not particularly limited, but is preferably in the range of 0.1 to 5 parts by mass, and more preferably 1 to 4 parts by mass, per 100 parts by mass of the rubber component (A).

[0198] The content of the zinc oxide (zinc white) is not particularly limited, but is preferably in the range of 0.1 to 10 parts by mass, more preferably 1 to 8 parts by mass, per 100 parts by mass of the rubber component (A).

[0199] Examples of the tackifier include rosin-based resins, terpene-based resins, petroleum-based resins, phenol-based resins, coal-based resins, and xylene-based resins, and among these, petroleum-based resins are preferred. ５ based resin, C ５ -C ９ based resin, C ９ The content of the tackifier is not particularly limited, and is preferably in the range of 0.1 to 5 parts by mass, and more preferably 0.5 to 3 parts by mass, per 100 parts by mass of the rubber component (A).

[0200] Examples of the vulcanization accelerator include sulfenamide vulcanization accelerators, guanidine vulcanization accelerators, thiazole vulcanization accelerators, thiuram vulcanization accelerators, and dithiocarbamate vulcanization accelerators. These vulcanization accelerators may be used alone or in combination of two or more. The content of the vulcanization accelerator is not particularly limited, and is preferably in the range of 0.1 to 5 parts by mass, more preferably 0.2 to 4 parts by mass, per 100 parts by mass of the rubber component (A).

[0201] The vulcanizing agent may be sulfur, etc. The content of the vulcanizing agent is preferably in the range of 0.1 to 6 parts by mass, more preferably 0.5 to 3 parts by mass, in terms of sulfur content, per 100 parts by mass of the rubber component (A).

[0202] -Method for producing rubber composition for tire- The method for producing the rubber composition for tire is not particularly limited, but the rubber composition for tire can be produced, for example, by blending various components appropriately selected as necessary with the above-mentioned rubber component (A) and antioxidant (B), and kneading, heating, extruding, etc. The obtained rubber composition can be vulcanized to produce a vulcanized rubber.

[0203] 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.

[0204] 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.

[0205] 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.

[0206] 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.

[0207] -Application- The rubber composition for a tire of this embodiment is particularly suitable for use in a tire tread. By using the rubber composition for a tire of this embodiment in a tire tread, it is possible to improve the fuel economy and abrasion resistance of the tire while suppressing the occurrence of cracks on the tread surface.

[0208] <Tire> The tire of this embodiment is characterized by including the above-described rubber composition for a tire. Since the tire of this embodiment includes the above-described rubber composition for a tire, the occurrence of cracks is suppressed while achieving both low fuel consumption and wear resistance. The rubber composition is applied to the tread rubber of the tire.

[0209] The tire of this embodiment 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 been subjected to a pre-vulcanization step or the like and then further vulcanizing it. The tire of this embodiment 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.

[0210] 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.

[0211] <Method for Synthesizing Modified BR-1> 283 g of cyclohexane, 50 g of 1,3-butadiene, 0.0057 mmol of 2,2-ditetrahydrofurylpropane, and 0.513 mmol of hexamethyleneimine (HMI) were added to a dried, nitrogen-purged, approximately 900 mL pressure-resistant glass vessel, and 0.57 mmol of n-butyllithium (BuLi) was then added. Polymerization was then carried out for 4.5 hours in a 50°C warm water bath equipped with a stirrer. The polymerization conversion rate was nearly 100%. Next, 0.100 mmol of tin tetrachloride was quickly added to this polymerization reaction system as a modifier (coupling agent), and the mixture was stirred at 50°C for an additional 30 minutes to carry out the modification reaction. Thereafter, 0.5 mL of an isopropanol solution of 2,6-di-t-butyl-p-cresol (BHT) (BHT concentration: 5% by mass) was added to the polymerization reaction system to terminate the reaction, and the mixture was further dried in a conventional manner to obtain a modified butadiene rubber having tin atoms (HMI-BR-Sn: Modified BR-1). １ The amount of vinyl bonds in the butadiene moiety was measured from the integral ratio of the H-NMR spectrum and was found to be 14%. The glass transition temperature (Tg) was calculated from the inflection point of the DSC curve and was found to be −95° C. The coupling rate was calculated from the ratio of the peak area on the highest molecular weight side to the entire area of ​​the molecular weight distribution curve by gel permeation chromatography (GPC) and was found to be 65%.

[0212] <Method for synthesizing modified BR-2> A 5-L autoclave purged with nitrogen was charged with 2.4 kg of cyclohexane and 300 g of 1,3-butadiene under nitrogen. A catalyst prepared by reacting and aging the catalyst components (a cyclohexane solution of neodymium versatate (0.09 mmol), a toluene solution of methylalumoxane (MAO) (1.8 mmol), a toluene solution of diisobutylaluminum hydride (DIBAH) (5.0 mmol) and diethylaluminum chloride (0.18 mmol) and 1,3-butadiene (4.5 mmol) at 50°C for 30 minutes at 50°C was then added, and polymerization was carried out at 80°C for 60 minutes. The reaction conversion of 1,3-butadiene was nearly 100%. 200 g of this polymer solution was withdrawn, and a methanol solution containing 1.5 g of 2,4-di-tert-butyl-p-cresol was added to terminate the polymerization. The solvent was then removed by steam stripping, and the mixture was dried on a roll at 110°C to obtain a pre-modified polymer (butadiene rubber). Analysis of the obtained pre-modified polymer revealed that the 1,4-cis bond content was 97.0% and the 1,2-vinyl bond content was 1.1% by infrared spectroscopy (Morello method), the molecular weight distribution (Mw / Mn) determined by gel permeation chromatography (GPC) was 2.3, and the Mooney viscosity (ML １＋４ , 100°C) was 18. Furthermore, the remaining polymer solution was kept at a temperature of 60°C, and a toluene solution of 3-glycidoxypropyltrimethoxysilane (GPMOS) (4.5 mmol) was added, followed by reaction for 30 minutes. Subsequently, a toluene solution of tetra 2-ethylhexyl titanate (EHOTi) (13.5 mmol) was added, and the mixture was mixed for 30 minutes. Thereafter, a methanol solution containing 1.5 g of 2,4-di-tert-butyl-p-cresol was added, yielding 2.5 kg of a modified polymer solution. Next, the modified polymer solution was added to 20 L of an aqueous solution adjusted to pH 10 with sodium hydroxide, and a condensation reaction was carried out at 110°C for 2 hours, with removal of the solvent, and the mixture was dried on a roll at 110°C to yield a modified butadiene rubber (modified BR-2). Analysis of the resulting modified butadiene rubber (modified BR-2) revealed that the molecular weight distribution (Mw / Mn) determined by GPC was 2.7, and the Mooney viscosity (ML １＋４ , 125°C) was 43.

[0213] <Synthesis Method of Modified BR-3> A cyclohexane solution of 1.4 kg, 250 g of 1,3-butadiene, and 0.285 mmol of 2,2-ditetrahydrofurylpropane was poured into a nitrogen-purged 5-L autoclave under nitrogen. 2.85 mmol of n-butyllithium (BuLi) was added to the mixture, and polymerization was carried out for 4.5 hours in a 50°C warm water bath equipped with a stirrer. The reaction conversion of 1,3-butadiene was nearly 100%. A portion of the polymer solution was withdrawn into a methanol solution containing 1.3 g of 2,6-di-tert-butyl-p-cresol to terminate the polymerization. The solvent was then removed by steam stripping, and the mixture was dried on a roll at 110°C to obtain unmodified polybutadiene. The microstructure (vinyl bond content) of the obtained unmodified polybutadiene was measured, and the vinyl bond content was found to be 30% by mass. The resulting polymer solution was maintained at 50°C without deactivating the polymerization catalyst, and 1129 mg (3.364 mmol) of N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane with protected primary amino groups was added, and the modification reaction was carried out for 15 minutes. Subsequently, 8.11 g of tetrakis(2-ethyl-1,3-hexanediolato)titanium, a condensation accelerator, was added, and the mixture was stirred for an additional 15 minutes. Finally, 242 mg of silicon tetrachloride as a metal halide compound and 2,6-di-tert-butyl-p-cresol were added to the polymer solution after the reaction. Next, the solvent was removed and the protected primary amino groups were deprotected by steam stripping, and the rubber was dried using a roll heated to 110°C to obtain a primary amine-modified butadiene rubber (Modified BR-3). The microstructure (vinyl bond content) of the resulting modified butadiene rubber (Modified BR-3) was measured, and the vinyl bond content was found to be 30% by mass.

[0214] <Synthesis Method of Copolymer-1> Under a nitrogen atmosphere, 65 parts by mass of cyclopentene, 35 parts by mass of 2-norbornene, 300 parts by mass of cyclohexane, and 0.066 parts by mass of 1-hexene were added to a glass reaction vessel equipped with a stirrer. Next, 0.024 parts by mass of the ring-opening polymerization catalyst dichloro-(3-phenyl-1H-inden-1-ylidene)bis(tricyclohexylphosphine)ruthenium(II) dissolved in 1 part by mass of toluene was added, and the polymerization reaction was carried out at 20°C for 2 hours. After the polymerization reaction, the polymerization was terminated by adding excess vinyl ethyl ether. The polymerization solution was poured into a large excess of methanol containing 2,6-di-t-butyl-p-cresol (BHT), and the precipitated polymer was recovered, washed with methanol, and then vacuum-dried at 50°C for 24 hours to obtain 67 parts by mass of Copolymer-1.

[0215] <Synthesis Method of Copolymer-2> Under a nitrogen atmosphere, 77 parts by mass of cyclopentene, 23 parts by mass of dicyclopentadiene, 300 parts by mass of cyclohexane, and 0.069 parts by mass of 1-hexene were added to a glass reaction vessel equipped with a stirrer. Next, 0.024 parts by mass of the ring-opening polymerization catalyst dichloro-(3-phenyl-1H-inden-1-ylidene)bis(tricyclohexylphosphine)ruthenium(II) dissolved in 1 part by mass of toluene was added, and the polymerization reaction was carried out at 40°C for 2 hours. After the polymerization reaction, the polymerization was terminated by adding excess vinyl ethyl ether. The polymerization solution was poured into a large excess of methanol containing 2,6-di-t-butyl-p-cresol (BHT), and the precipitated polymer was recovered, washed with methanol, and then vacuum-dried at 50°C for 24 hours to obtain 60 parts by mass of Copolymer-2.

[0216] <Analysis of Copolymers> The molecular weight of each synthesized copolymer and the proportion of structural units derived from each monomer were measured by the following method. The results are shown in Table 1.

[0217] (1) Molecular Weight Measurement was performed using a gel permeation chromatography (GPC) system "HLC-8220" (manufactured by Tosoh Corporation) with two H-type columns "HZ-M" (manufactured by Tosoh Corporation) connected in series, with tetrahydrofuran as the solvent, at a column temperature of 40°C. A differential refractometer "RI-8320" (manufactured by Tosoh Corporation) was used as the detector. The weight average molecular weight (Mw) of the copolymer was measured as a polystyrene equivalent value.

[0218] (2) Proportion of structural units derived from each monomer The proportion of structural units derived from each monomer constituting the copolymer is １ It was determined by H-NMR spectrum measurement.

[0219]

[0220] Comparative Examples 1 and 2 Each rubber composition was prepared by blending and kneading the components according to the formulation shown in Table 2. Each rubber composition further contained the following compounding ingredients in addition to the components shown in Table 2: 2 parts by mass of hardened fatty acid, 3.5 parts by mass of zinc oxide, 1 part by mass of resin, 1.4 parts by mass of sulfenamide vulcanization accelerator, and 1.05 parts by mass of sulfur, per 100 parts by mass of the rubber component. The resulting rubber compositions were evaluated for fuel economy and abrasion resistance using the methods described below. Furthermore, each rubber composition was evaluated for ozone resistance using the method described below.

[0221] (3) Fuel Economy The loss tangent (tan δ) of a test piece made from the obtained rubber composition was measured using a viscoelasticity measuring device (TA Instruments) under conditions of a temperature of 50°C, a strain of 10%, and a frequency of 15 Hz. In addition, the modulus at 50% strain (M50) [MPa] of a test piece made from the obtained rubber composition was measured at room temperature. The evaluation results were indexed, with tan δ / M50 of Comparative Example 1 set to 100. The smaller the index value, the smaller the tan δ and the better the fuel economy. The index values ​​were classified according to the following criteria, and the evaluation results of each example are shown in Table 2. A: Index value is 90 or less B: Index value is more than 90 and less than 100 C: Index value is 100 or more

[0222] (4) Abrasion Resistance According to JIS K 6264-2:2005, sandpaper was attached to the grinding wheel using a Lambourn abrasion tester manufactured by Ueshima Seisakusho, and the amount of abrasion was measured at room temperature with a slip rate of 12%. The evaluation results were indexed, with the reciprocal of the amount of abrasion in Comparative Example 1 set as 100. The larger the index value, the smaller the amount of abrasion and the more excellent the abrasion resistance. The index values ​​were classified according to the following criteria, and the evaluation results for each example are shown in Table 2. A: Index value of 160 or more B: Index value greater than 100 and less than 160 C: Index value of 100 or less

[0223] (5) Ozone Resistance A dynamic ozone degradation test (a test in which repeated strain is applied) is conducted in accordance with ISO 1431 (JIS K 6259), and the sample is observed at 20x magnification using a microscope. The observed samples are ranked according to the size and depth of cracks and classified according to the following criteria (1 to 5), with smaller numbers indicating better results. (Ranking by crack size and depth) 1: Not visible to the naked eye but visible with a 10x magnifying glass. 2: Visible to the naked eye. 3: Deep and relatively large cracks (less than 1 mm). 4: Deep and large cracks (1 mm or more but less than 3 mm). 5: Cracks of 3 mm or more or likely to cause breakage.

[0224] Examples 1 to 8 and Comparative Example 3 Each rubber composition was produced according to a conventional method with the formulation shown in Table 2. Each rubber composition further contained the following compounding ingredients per 100 parts by mass of the rubber component in addition to the components shown in Table 2: 2 parts by mass of hardened fatty acid, 3.5 parts by mass of zinc oxide, 1 part by mass of resin, 1.4 parts by mass of sulfenamide vulcanization accelerator, and 1.05 parts by mass of sulfur. Each rubber composition was evaluated for fuel economy, wear resistance, and ozone resistance using the methods described above.

[0225]

[0226] *1 NR: Natural rubber *2 BR: Butadiene rubber, manufactured by UBE Elastomers, product name "BR150L" *3 Modified BR-1: Modified butadiene rubber synthesized by the above method *4 Modified BR-2: Modified butadiene rubber synthesized by the above method *5 Modified SBR: Manufactured by ENEOS Material Corporation, product name "SL563", solution polymerization styrene-butadiene rubber, Sn modified *6 Modified BR-3: Modified butadiene rubber synthesized by the above method *7 Copolymer-1: Copolymer of cyclopentene and norbornene-based compound synthesized by the above method *8 Copolymer-2: Copolymer of cyclopentene and norbornene-based compound synthesized by the above method *9 Antioxidant-1: N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (6PPD), Ouchi Shinko Chemical Industry Co., Ltd. "Nocrac (registered trademark) 6C" *10 Antioxidant-2: 4,4'-bis(2-octylamino)triphenylamine, a triphenylamine-based antioxidant represented by the following structural formula (2-a): *11 Antioxidant-3: 4,4'-bis(2-octylamino)-4''-methoxytriphenylamine, a triphenylamine-based antioxidant represented by the following structural formula (2-b) *12 Antioxidant-4: 4,4',4''-tris(1,3-dimethylbutylamino)triphenylamine, a triphenylamine-based antioxidant represented by the following structural formula (2-c) *13 Carbon Black-1: Cetyltrimethylammonium bromide (CTAB) adsorption specific surface area is 130 m ２ / g and dibutyl phthalate (DBP) absorption capacity of 140 mL / 100 g *14 Carbon black-2: N234, manufactured by Tokai Carbon Co., Ltd., trade name "SEAST 7HM", CTAB adsorption specific surface area = 119 m ２ / g

[0227] Table 2 shows that when a rubber composition containing the copolymer (A1) of cyclopentene and a norbornene-based compound, the modified polymer (A2), and the triphenylamine-based antioxidant (B1) of formula (2) is applied to a tire, it is possible to suppress the occurrence of cracks while achieving both low fuel consumption and wear resistance of the tire.

Claims

1. A rubber composition comprising a rubber component (A) and an antioxidant (B), wherein the rubber component (A) is a rubber component containing cyclopentene and a compound represented by the following general formula (1): [In the formula, R １１ ~R １４ each independently represents a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a substituent containing a halogen atom, a silicon atom, an oxygen atom, or a nitrogen atom; R １２ and R １３ may be bonded to each other to form a ring, and m1 is an integer of 0 to 2.], and a modified polymer (A2), wherein the antioxidant (B) is a compound represented by the following general formula (2): [In the formula, R ２１ and R ２２ each independently represents a linear or branched alkyl group having 1 to 12 carbon atoms or a cycloalkyl group having 5 to 8 carbon atoms; R ２３ represents hydrogen, a linear or branched alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, -NH-R ２３１ , or -O-R ２３２ where R ２３１ and R ２３２ and each independently represent a linear or branched alkyl group having 1 to 12 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms.].

2. The rubber composition for tires according to claim 1, wherein the norbornene compound represented by the general formula (1) is 2-norbornene and / or dicyclopentadiene.

3. The rubber composition for tires according to claim 1, wherein the content of the copolymer (A1) of cyclopentene and a norbornene-based compound is 20 to 90 parts by mass per 100 parts by mass of the rubber component (A).

4. The rubber composition for tires according to claim 1, wherein the copolymer (A1) of cyclopentene and a norbornene-based compound contains 20 to 75 mass % of structural units derived from cyclopentene.

5. The rubber composition for tires according to claim 2, wherein the copolymer (A1) of cyclopentene and a norbornene-based compound contains 10 to 60 mass % of structural units derived from 2-norbornene.

6. The rubber composition for tires according to claim 2, wherein the copolymer (A1) of cyclopentene and a norbornene-based compound contains 10 to 60 mass % of structural units derived from dicyclopentadiene.

7. The rubber composition for tires according to claim 1, wherein the modified polymer (A2) is a modified butadiene rubber or a modified styrene-butadiene rubber having a nitrogen-containing functional group.

8. The rubber composition for tires according to claim 1, wherein the mass ratio (B / A1C) of the antioxidant (B) to the structural unit (A1C) derived from cyclopentene in the copolymer (A1) is 0.006 to 0.

5.

9. The rubber composition for tires according to claim 2, wherein the mass ratio (B / A1N) of the antioxidant (B) to the structural units (A1N) derived from 2-norbornene in the copolymer (A1) is 0.008 to 1.

10. The rubber composition for tires according to claim 2, wherein the mass ratio (B / A1D) of the antioxidant (B) to the structural units (A1D) derived from dicyclopentadiene in the copolymer (A1) is 0.008 to 1.

11. R in the above general formula (2) ２１ and R ２２ The rubber composition for a tire according to claim 1, wherein is an alkyl group selected from the group consisting of an isopropyl group, a 1,3-dimethylbutyl group, a 2-octyl group, and a 1,4-dimethylpentyl group.

12. R in the above general formula (2) ２１ and R ２２ The rubber composition for a tire according to claim 1, wherein has 2 to 8 carbon atoms.

13. The rubber composition for tires according to claim 1, wherein the content of the antioxidant (B) is 0.5 to 10 parts by mass per 100 parts by mass of the rubber component (A), the antioxidant (B) further contains a quinoline-based antioxidant (B2), and the proportion of the quinoline-based antioxidant (B2) in the antioxidant (B) is 5 to 50% by mass.

14. The antioxidant (B) further comprises a compound represented by the following general formula (3): [In the formula, R ３１ and R ３２ are each independently a monovalent saturated hydrocarbon group, and a proportion of the amine-based antioxidant (B3) in the antioxidant (B) is 0.1 to 80 mass %.

15. The antioxidant (B) further comprises a compound represented by the following general formula (4): [In the formula, R ４１ and R ４２ represents a phenyl group, and m4 represents an integer of 7 or greater.], and a proportion of the amine-based antioxidant (B4) in the antioxidant (B) is 0.1 to 80 mass %.

16. The rubber composition for tires according to claim 1, which is used for tire treads.

17. A tire comprising the rubber composition for tires according to claim 1.

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