Rubber composition for tires and tires

Abstract

The present invention provides a tire rubber composition that utilizes sustainable materials while simultaneously achieving workability and improved fuel efficiency and wear resistance when applied to tires. [Solution] The solution comprises a rubber component and a filler, wherein the rubber component is cyclopentene and formula (1): TIFF2026105799000006.tif54168 [R 1 ~R 4 R independently represents a hydrogen atom, a hydrocarbon group, or a substituent containing a halogen atom, a silicon atom, an oxygen atom, or a nitrogen atom. 2 and R 3 The rubber composition for tires contains a copolymer with a norbornene compound represented by [ ], which may be bonded to each other to form a ring, and m is an integer from 0 to 2, and the filler contains recycled carbon black.

Description

[Technical Field]

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

[0002] In recent years, from the perspective of social sustainability, there has been a growing demand for the use of so-called sustainable materials, such as materials derived from biological resources (biomass resources) and recycled resources, in the components used in tires. Furthermore, technological development is desired to increase the usage rate of sustainable materials in rubber compositions applied to tires.

[0003] Furthermore, in line with the growing global concern for environmental issues and the resulting global movement towards carbon dioxide emission regulations, there is a growing demand for more fuel-efficient automobiles. To meet this demand, tire performance is also required to improve fuel efficiency (i.e., reduce losses). In response to this, Patent Documents 1 and 2 below disclose rubber compounding for passenger car tires and rubber compounding for heavy-duty truck and bus tires, which include a specific long-chain branched cyclopentene ring-opening rubber (LCB-CPR). These rubber compoundings are said to be effective in reducing tire rolling resistance, improving wet skid resistance, and improving wear resistance. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2021 / 178233 [Patent Document 2] International Publication No. 2021 / 178235 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, when components manufactured by replacing fossil fuel-derived materials with sustainable materials are applied to tires, a problem arises in that the tire's performance cannot be maintained. Furthermore, the inventors have investigated and found that even with the technologies described in Patent Documents 1 and 2, it is difficult to apply sustainable materials while simultaneously achieving workability of the rubber composition and low fuel consumption and wear resistance of the tire to which the rubber composition is applied, and there is still room for improvement.

[0006] Therefore, the present invention aims to solve the problems of the above-mentioned prior art and provide a tire rubber composition that uses sustainable materials while achieving both workability and low fuel consumption and wear resistance when applied to tires. Furthermore, a further objective of the present invention is to provide a tire that achieves both productivity, low fuel consumption, and wear resistance while using sustainable materials. [Means for solving the problem]

[0007] The gist of the rubber composition for tires and the tire of the present invention, which solves the above problems, is as follows.

[0008] [1] Containing rubber components and fillers, The aforementioned rubber component is cyclopentene and the following general formula (1): [ka] [In the formula, R 1 ~R 4 Each of these 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, and R 2 and R 3 These may be bonded together to form a ring, and m is an integer from 0 to 2. The copolymer includes a norbornene compound represented by ]. A rubber composition for tires, characterized in that the filler contains recycled carbon black. The rubber composition for tires described in [1] above can achieve both workability and low fuel consumption and wear resistance of the tire when applied to a tire, while using sustainable materials.

[0009] [2] The tire rubber composition according to [1], wherein the content of the copolymer of cyclopentene and norbornene compound is 20 to 90 parts by mass per 100 parts by mass of the rubber component. The tire rubber composition described in [2] above can be applied to tires to improve the balance between fuel efficiency and wear resistance of the tires.

[0010] [3] The rubber composition for tires according to [1] or [2], wherein the copolymer of cyclopentene and norbornene compound has a weight-average molecular weight (Mw) of 200,000 to 1,000,000. The tire rubber composition described in [3] above can be applied to tires to further improve their fuel efficiency and wear resistance.

[0011] [4] The tire rubber composition according to any one of [1] to [3], wherein the copolymer of cyclopentene and norbornene compound has a content of 20 to 75% by mass of structural units derived from cyclopentene. The tire rubber composition described in [4] above can be applied to tires to further improve the fuel efficiency and wear resistance of the tires.

[0012] [5] The tire rubber composition according to any one of [1] to [4], wherein the copolymer of cyclopentene and norbornene-based compound has a content of 10 to 60% by mass of structural units derived from 2-norbornene. The tire rubber composition described in [5] above can be applied to tires to further improve the fuel efficiency and wear resistance of the tires.

[0013] [6] The tire rubber composition according to any one of [1] to [5], wherein the copolymer of cyclopentene and norbornene-based compound has a content of dicyclopentadiene-derived structural units of 10 to 60% by mass. The tire rubber composition described in [6] above can be applied to tires to further improve their fuel efficiency and wear resistance.

[0014] [7] The tire rubber composition according to any one of [1] to [6], wherein the content of the filler is 5 to 150 parts by mass per 100 parts by mass of the rubber component. The tire rubber composition described in [7] above offers improved workability and, when applied to tires, can further improve the tire's fuel efficiency and wear resistance.

[0015] [8] The tire rubber composition according to any one of [1] to [7], wherein the proportion of recycled carbon black in the filler is 10 to 100% by mass. The tire rubber compositions described in [8] above have a high rate of sustainable material use, improved workability, and can further improve the fuel efficiency and wear resistance of tires when applied to them.

[0016] [9] The rubber composition for tires according to any one of [1] to [8], wherein the rubber component further comprises butadiene rubber. The tire rubber composition described in [9] above can be applied to tires to further improve the fuel efficiency and wear resistance of the tires.

[0017] A tire characterized by comprising a tire rubber composition described in any one of [1] to [9]. The tire of the present invention described in

[10] above can achieve productivity, low fuel consumption, and wear resistance while applying sustainable materials. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a tire rubber composition that uses sustainable materials while achieving both workability and low fuel consumption and wear resistance when applied to tires. Furthermore, according to the present invention, it is possible to provide a tire that achieves both productivity, low fuel consumption, and wear resistance while using sustainable materials. [Modes for carrying out the invention]

[0019] The rubber composition for tires and the tires of the present invention will be described in detail below, based on embodiments thereof.

[0020] <Definition> The compounds described herein may be derived in part or in whole from fossil resources, from biological resources such as plant resources, or from recycled resources such as used tires. They may also be derived from a mixture of two or more of fossil resources, biological resources, and recycled resources.

[0021] In this specification, "sustainable materials" refers to materials derived from biological resources (biomass resources) and materials derived from recycled resources.

[0022] In this specification, the term "biomass resources" refers to carbon-neutral organic resources of biological origin, including, for example, those stored in the form of starch and cellulose, the bodies of animals that feed on plants, and products obtained by processing plants and animals, excluding fossil resources (petroleum, coal, natural gas, etc.). These biological resources may be edible or inedible, but it is preferable that they are inedible so as not to compete with food and from the viewpoint of efficient resource utilization.

[0023] In this specification, the term "recycled resources" refers to resources obtained by recycling products that have been used, collected without being used, or discarded. For example, recycled resources include resources obtained by recycling used rubber products such as used tires.

[0024] <Rubber composition for tires> The tire rubber composition of this embodiment comprises a rubber component and a filler. In the tire rubber composition of this embodiment, the rubber component comprises cyclopentene and the following general formula (1): [ka] [In the formula, R 1 ~R 4 Each of these 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, and R 2 and R 3 The compounds may bond to each other to form a ring, and m is an integer from 0 to 2. The compound contains a copolymer of a norbornene compound represented by [ ] (also simply called a "polymer of cyclopentene and a norbornene compound" or "polymer"), and the filler is characterized in that it contains recycled carbon black.

[0025] In the tire rubber composition of this embodiment, the copolymer of cyclopentene and norbornene-based compound is characterized not only by having crosslinking points but also by the entanglement of polymer chains. Generally, when a filler is blended with a rubber component, a reinforcing layer consisting of the filler and the rubber component is formed around the filler, and this reinforcing layer contributes to improving the reinforcing properties of the rubber composition, thereby improving abrasion resistance and other properties. Furthermore, in the tire rubber composition of this embodiment, the reinforcing layer formed around the filler is specifically increased due to the entanglement of the polymer chains as described above, thereby further improving wear resistance and other properties. In addition, in the tire rubber composition of this embodiment, the specific increase in the reinforcing layer due to the entanglement of the polymer chains of the copolymer of cyclopentene and norbornene compound reduces hysteresis loss and improves fuel efficiency. On the other hand, in the tire rubber composition of this embodiment, since recycled carbon black is a material derived from recycled resources, incorporating the recycled carbon black into the rubber composition can increase the use rate of sustainable materials in tires to which the rubber composition is applied. While the use of recycled carbon black instead of regular unused carbon black tends to worsen the workability of the rubber composition and reduce its abrasion resistance, the tire rubber composition of this embodiment exhibits high affinity between the copolymer of cyclopentene and norbornene-based compounds and recycled carbon black. This improves the dispersibility of the recycled carbon black in the rubber composition, resulting in lower unvulcanized viscosity and improved workability (particularly improved rollability and extrusion). Furthermore, the improved dispersibility of recycled carbon black further reduces hysteresis loss, leading to improved fuel efficiency. Therefore, the tire rubber composition of this embodiment can achieve both workability and low fuel consumption and wear resistance when applied to tires, while using sustainable materials. Furthermore, according to the tire rubber composition of this embodiment, as described above, the dispersibility of recycled carbon black is improved, allowing the reinforcing effect of recycled carbon black to be fully realized and improving fracture characteristics.

[0026] (Rubber component) The tire rubber composition of this embodiment contains a rubber component, which provides the composition with rubber elasticity. The rubber component of the tire rubber composition of this embodiment contains a copolymer of cyclopentene and a norbornene-based compound represented by the above general formula (1), and may further contain other rubbers.

[0027] -Copolymer of cyclopentene and norbornene-based compounds- The copolymer of the cyclopentene and the norbornene-based compound contains a structural unit derived from cyclopentene and a structural unit derived from the norbornene-based compound represented by the general formula (1). Further, in one preferred embodiment, the copolymer of the cyclopentene and the norbornene-based compound is a ring-opening copolymer, and particularly, it is a cyclopentene ring-opening copolymer. Further, in one preferred embodiment, the copolymer of the cyclopentene and the norbornene-based compound is a linear polymer or a branched polymer, and particularly, it is a linear polymer.

[0028] In the general formula (1) above, R 1 ~R 4 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, and R 2 and R 3 may be bonded to each other to form a ring, and m is an integer of 0 to 2. Here, examples of the hydrocarbon group having 1 to 20 carbon atoms include an alkyl group such as 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 neopentyl group, a hexyl group, an octyl group; an alkenyl group such as a vinyl group, an allyl group, a 2-pentenyl group, a 3-pentenyl group, a 4-methyl-3-pentenyl group; an aryl group such as a phenyl group, a tolyl group, a 2,6-dimethylphenyl group, a 2,6-diisopropylphenyl group, a naphthyl group; an aralkyl group such as a benzyl group, a phenethyl group; etc.

[0029] Examples of the norbornene-based compound 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 Also called "deca-8-ene". Bicyclo[2.2.1]hepto-2-enes, which are unsubstituted or have hydrocarbon substituents, such as ) Tetracyclo[6.2.1.1 3,6 .0 2,7 ] Dodeca-4-ene, 9-methyltetracyclo[6.2.1.1 3,6 .0 2,7 ] Dodeca-4-ene, 9-ethyltetracyclo[6.2.1.1 3,6 .0 2,7 ] Dodeca-4-ene, 9-cyclohexyltetracyclo[6.2.1.1 3,6 .0 2,7 ] Dodeca-4-ene, 9-cyclopentyltetracyclo[6.2.1.1 3,6 .0 2,7 ] Dodeca-4-ene, 9-methylenetetracyclo[6.2.1.1 3,6 .0 2,7 ] Dodeca-4-ene, 9-ethylidenetetracyclo[6.2.1.1 3,6 .0 2,7 ] Dodeca-4-ene, 9-vinyltetracyclo[6.2.1.1 3,6 .0 2,7 ] Dodeca-4-ene, 9-propenyltetracyclo[6.2.1.1 3,6 .0 2,7 ] Dodeca-4-ene, 9-cyclohexenyltetracyclo[6.2.1.1 3,6 .0 2,7 ] Dodeca-4-ene, 9-cyclopentenyltetracyclo[6.2.1.1 3,6 .0 2,7 ] Dodeca-4-ene, 9-phenyltetracyclo[6.2.1.1 3,6.0 2,7 ] Tetracyclo[6.2.1.1] unsubstituted or hydrocarbon substituents such as dodeca-4-ene 3,6 .0 2,7 Dodeca-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 ] Dodeca-9-ene-4-carboxylate methyl, 4-methyltetracyclo[6.2.1.1 3,6 .0 2,7 ] Tetracyclo[6.2.1.1 3,6 .0 2,7 Dodeca-4-enes; Bicyclo[2.2.1]hept-2-ene compounds 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 ] Dodeca-9-ene-4-carboxylic acid, tetracyclo[6.2.1.1 3,6 .0 2,7 ] Dodeca-9-ene-4,5-dicarboxylic acid, tetracyclo[6.2.1.1 3,6 .0 2,7 ] Tetracyclo[6.2.1.1 3,6 .0 2,7 Dodeca-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 ] Dodeca-9-ene-4-methanol, tetracyclo[6.2.1.1 3,6 .0 2,7 ] Tetracyclo[6.2.1.1 3,6 .0 2,7 Dodeca-4-enes; Bicyclo[2.2.1]hept-2-ene compounds having a hydrocarbonyl group, such as 5-norbornene-2-carbaldehyde; Tetracyclo[6.2.1.1 3,6 .0 2,7 ] Tetracyclo[6.2.1.1] such as dodeca-9-ene-4-carbaldehyde, which have a hydrocarbonyl group. 3,6 .0 2,7 Dodeca-4-enes; Bicyclo[2.2.1]hept-2-ene compounds having an alkoxycarbonyl group and a hydroxycarbonyl group, such as 3-methoxycarbonyl-5-norbornene-2-carboxylic acid; Bicyclo[2.2.1]hept-2-ene compounds having a carbonyloxy group, such as 5-norbornene-2-yl acetate, 2-methyl-5-norbornene-2-yl acetate, 5-norbornene-2-yl acrylate, and 5-norbornene-2-yl methacrylate; 9-tetracycloacetic acid [6.2.1.1 3,6 .0 2,7 ] Dodeca-4-enyl, 9-tetracycloacrylate [6.2.1.1 3,6 .0 2,7 ] Dodeca-4-enyl, 9-tetracyclomethacrylate [6.2.1.1 3,6 .0 2,7Tetracyclo[6.2.1.1 3,6 .0 2,7 dodeca - 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, 5 - norbornene - 2,3 - dicarboxylic acid imide; Tetracyclo[6.2.1.1 3,6 .0 2,7 dodeca - 9 - ene - 4 - carbonitrile, tetracyclo[6.2.1.1 3,6 .0 2,7 dodeca - 9 - ene - 4 - carboxamide, tetracyclo[6.2.1.1 3,6 .0 2,7 dodeca - 9 - ene - 4,5 - dicarboxylic acid imide and the like having a functional group containing a nitrogen atom, tetracyclo[6.2.1.1 3,6 .0 2,7 dodeca - 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 dodeca - 4 - ene and the like having a halogen atom, tetracyclo[6.2.1.1 3,6 .0 2,7 dodeca - 4 - enes; Bicyclo[2.2.1]hept - 2 - enes having a functional group containing a silicon atom such as 5 - trimethoxysilyl - 2 - norbornene, 5 - triethoxysilyl - 2 - norbornene; 4 - trimethoxysilyltetracyclo[6.2.1.1 3,6 .0 2,7 dodeca - 9 - ene, 4 - triethoxysilyltetracyclo[6.2.1.1 3,6 .0 2,7 dodeca - 9 - ene and the like having a functional group containing a silicon atom, tetracyclo[6.2.1.1 3,6 .0 2,7Dodeca-4-enes; etc. are exemplified. The norbornene compound may be used alone or in combination of two or more.

[0030] As the norbornene compound represented by the above general formula (1), in the above general formula (1), those in which m is 0 or 1 are preferred, and those in which m is 0 are more preferred. Also, in the above general formula (1), R 1 ~R 4 may be the same or different.

[0031] Among the norbornene compounds represented by the above general formula (1), from the viewpoints of low fuel consumption and abrasion resistance of the rubber composition, R 1 ~R 4 in the above general formula (1) is preferably a hydrogen atom, a linear 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. In this case, R 1 ~R 4 only needs to be a group that does not bond to each other and does not form a ring, is not particularly limited, may be the same or different, and R 1 ~R 4 is preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Also, in this case too, those in which m is 0 or 1 are preferred, and those in which m is 0 are more preferred. R 1 ~R 4 As the norbornene compound in which is a hydrogen atom, a linear 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, bicyclo[2.2.1]hept-2-enes having an unsubstituted or hydrocarbon substituent are preferred, and among them, 2-norbornene is particularly preferred.

[0032] Also, as the norbornene compound represented by the above general formula (1), a compound in which R 2 and R 3 are bonded to each other to form a ring is also preferred. Here, R 2 and R 3Specific examples of ring structures formed by the bonding of these rings include cyclopentane rings, cyclopentene rings, cyclohexane rings, cyclohexene rings, and benzene rings, which may form polycyclic structures and may also have substituents. Among these, cyclopentane rings, cyclopentene rings, and benzene rings are preferred, and compounds having a cyclopentene ring alone, or compounds having a polycyclic structure of a cyclopentane ring and a benzene ring are particularly preferred. 2 , R 3 Other than R 1 , R 4 R may be the same or different, and is preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. In this case, it is also preferable that m is 0. 2 and R 3 As norbornene compounds in which these are bonded to each other to form a ring, bicyclo[2.2.1]hepto-2-enes are preferred, either unsubstituted or having hydrocarbon substituents, and among these, dicyclopentadiene is particularly preferred.

[0033] The copolymer of cyclopentene and norbornene compound preferably contains cyclopentene-derived structural units in a proportion of 20 to 75% by mass, more preferably 25 to 70% by mass, even more preferably 30 to 65% by mass, and particularly preferably 35 to 60% by mass, relative to the total repeating structural units of the copolymer. By setting the proportion of cyclopentene-derived structural units in the copolymer to a range of 20 to 75% by mass, the fuel efficiency and wear resistance of the rubber composition containing the copolymer can be further improved, and by applying the rubber composition to a tire, the fuel efficiency and wear resistance of the tire can be further improved.

[0034] The copolymer of cyclopentene and norbornene compound has a content of structural units derived from the norbornene compound represented by the general formula (1) that is preferably 10 to 80% by mass, more preferably 20 to 70% by mass, even more preferably 25 to 65% by mass, and particularly preferably 40 to 65% by mass, relative to the total repeating structural units of the copolymer. By setting the content of structural units derived from the norbornene compound represented by the general formula (1) in the copolymer to a range of 10 to 80% by mass, the fuel efficiency and wear resistance of the rubber composition containing the copolymer can be further improved, and by applying the rubber composition to a tire, the fuel efficiency and wear resistance of the tire can be further improved.

[0035] In the copolymer of cyclopentene and norbornene-based compound, the norbornene-based compound represented by the above 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 readily available. Therefore, tire rubber compositions containing copolymers of cyclopentene and 2-norbornene and / or dicyclopentadiene are advantageous in terms of cost.

[0036] When 2-norbornene is used as the norbornene-based compound represented by the above general formula (1), the copolymer of cyclopentene and the norbornene-based compound preferably has a content of 2-norbornene-derived structural units of 10 to 60% by mass, and more preferably 20 to 60% by mass, relative to the total repeating structural units of the copolymer. By setting the content of 2-norbornene-derived structural units in the copolymer to a range of 10 to 60% by mass, the fuel efficiency and wear resistance of the rubber composition containing the copolymer can be further improved, and by applying the rubber composition to a tire, the fuel efficiency and wear resistance of the tire can be further improved.

[0037] When dicyclopentadiene is used as the norbornene compound represented by the above general formula (1), the copolymer of cyclopentene and the norbornene compound preferably has a content of dicyclopentadiene-derived structural units of 10 to 60% by mass, and more preferably 20 to 50% by mass, relative to the total repeating structural units of the copolymer. By setting the content of dicyclopentadiene-derived structural units in the copolymer to a range of 10 to 60% by mass, the fuel efficiency and wear resistance of the rubber composition containing the copolymer can be further improved, and by applying the rubber composition to a tire, the fuel efficiency and wear resistance of the tire can be further improved.

[0038] In one preferred embodiment, the copolymer of cyclopentene and norbornene-based compound may be a terpolymer of cyclopentene (CP), 2-norbornene (NB), and dicyclopentadiene (DCPD). Since the terpolymer of cyclopentene, 2-norbornene, and dicyclopentadiene has a significant effect in improving fuel efficiency, the rubber composition containing this terpolymer exhibits further improved fuel efficiency.

[0039] The copolymer of cyclopentene and norbornene compound may be copolymerized with other monomers that can copolymerize with cyclopentene and the norbornene compound represented by the general formula (1) above. 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 aromatic rings such as phenylcyclooctene, 5-phenyl-1,5-cyclooctadiene, and phenylcyclopentene. The content of structural units derived from other monomers in the copolymer of cyclopentene and norbornene compound is preferably 40% by mass or less, more preferably 30% by mass or less, relative to the total repeating structural units of the copolymer, and it is particularly preferable that structural units derived from other monomers are substantially absent.

[0040] The copolymer of cyclopentene and norbornene 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. Copolymers with a weight-average molecular weight (Mw) in the range of 200,000 to 1,000,000 are easy to manufacture and have good processability (workability). Furthermore, by setting the weight-average molecular weight (Mw) of the copolymer to the range of 200,000 to 1,000,000, the fuel efficiency and wear resistance of the rubber composition containing the copolymer can be further improved, and by applying the rubber composition to a tire, the fuel efficiency and wear resistance of the tire can be further improved. Furthermore, the copolymer of cyclopentene and norbornene-based compound preferably has a ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) (Mw / Mn, also called "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. Here, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the copolymer are polystyrene-converted values ​​measured by gel permeation chromatography (GPC).

[0041] The copolymer of cyclopentene and 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 is the ratio of cis to trans structures of double bonds present in the repeating units constituting the copolymer of cyclopentene and norbornene-based compound. By setting the cis / trans ratio of the copolymer within the above range, the fuel efficiency and wear resistance of the rubber composition containing the copolymer can be further improved, and by applying the rubber composition to a tire, the fuel efficiency and wear resistance of the tire can be further improved.

[0042] The copolymer of cyclopentene and norbornene compound has a glass transition temperature (Tg) preferably -80°C to 10°C, more preferably -75°C to 0°C, and even more preferably -70°C to -10°C. By setting the glass transition temperature (Tg) of the copolymer within the above range, the fuel efficiency and wear resistance of the rubber composition containing the copolymer can be further improved, and by applying the rubber composition to a tire, the fuel efficiency and wear resistance of the tire can be further improved. The glass transition temperature of the copolymer can be controlled, for example, by adjusting the type and amount of norbornene compound used. Here, the glass transition temperature (Tg) of the copolymer was measured using a differential scanning calorimeter (DSC) with a heating rate of 10°C / min.

[0043] The copolymer of cyclopentene and norbornene compound may have a modifying group at the end of the polymer chain. Having such a terminal modifying group can further increase the affinity to the filler, improve the dispersibility of the filler in the rubber composition, and as a result, further improve the processability (workability), fuel efficiency, and abrasion resistance of the rubber composition. The modifying group to be introduced at the end of the polymer chain of the copolymer is not particularly limited, but a modifying group containing an atom selected from the group consisting of atoms of Group 15 of the periodic table, atoms of Group 16 of the periodic table, and silicon atoms is preferred. As a modifying group for forming the terminal modifying group, a modifying group containing an atom selected from the group consisting of nitrogen atoms, oxygen atoms, phosphorus atoms, sulfur atoms, and silicon atoms is more preferred from the viewpoint of increasing the affinity to the filler, and among these, a modifying group containing an atom selected from the group consisting of nitrogen atoms, oxygen atoms, and silicon atoms is even more preferred.

[0044] Modified groups containing a nitrogen atom include amino groups, pyridyl groups, imino groups, amide groups, nitro groups, urethane bonding groups, or hydrocarbon groups containing any of these groups. Modified groups containing an oxygen atom include hydroxyl groups, carboxylic acid groups, ether groups, ester groups, carbonyl groups, aldehyde groups, epoxy groups, or hydrocarbon groups containing any of these groups. Modified groups containing a silicon atom include alkylsilyl groups, oxysilyl groups, or hydrocarbon groups containing any of these groups. Modified groups containing a phosphorus atom include phosphoric acid groups, phosphino groups, or hydrocarbon groups containing any of these groups. Modified groups containing a sulfur atom include sulfonyl groups, thiol groups, thioether groups, or hydrocarbon groups containing any of these groups. Furthermore, the modified group may contain multiple of the above-mentioned groups. Among these, from the viewpoint of further improving the processability (workability), fuel efficiency, and abrasion resistance of the rubber composition, amino groups, pyridyl groups, imino groups, amide groups, hydroxyl groups, carboxylic acid groups, aldehyde groups, epoxy groups, oxysilyl groups, or hydrocarbon groups containing any of these groups are preferred, and from the viewpoint of affinity to fillers (especially silica, etc.), oxysilyl groups are particularly preferred. Here, an oxysilyl group refers to a group having a silicon-oxygen bond.

[0045] Examples of the oxysilyl group include alkoxysilyl groups, aryloxysilyl groups, acyloxy groups, alkylsiloxysilyl groups, and arylsiloxysilyl groups. Furthermore, hydroxysilyl groups obtained by hydrolysis of alkoxysilyl groups, aryloxysilyl groups, or acyloxy groups can also be mentioned. Among these, alkoxysilyl groups are preferred from the viewpoint of affinity for silica. The alkoxysilyl group is a group formed by one or more alkoxy groups bonded to a silicon atom. Specific examples include trimethoxysilyl groups, dimethoxymethylsilyl groups, methoxydimethylsilyl groups, methoxydichlorosilyl groups, triethoxysilyl groups, diethoxymethylsilyl groups, ethoxydimethylsilyl groups, dimethoxyethoxysilyl groups, methoxydiethoxysilyl groups, and tripropoxysilyl groups.

[0046] The proportion of modified groups introduced at the polymer chain ends of the copolymer of cyclopentene and norbornene-based compound is not particularly limited, but it is preferably 10% or more, more preferably 20% or more, even more preferably 30% or more, and particularly preferably 40% or more, as a percentage of the number of copolymer chain ends with modified groups / total number of copolymer chain ends. A higher proportion of terminal modified groups is preferable because it increases the affinity to the filler. The method for measuring the proportion of modified groups introduced at the polymer chain ends is not particularly limited, but an example is when an oxysilyl group is introduced as the terminal modified group. 1 It can be determined from the peak area ratio corresponding to the oxysilyl group, which is obtained by 1H-NMR spectroscopy, and the number-average molecular weight (Mn) obtained from gel permeation chromatography (GPC).

[0047] The copolymer of cyclopentene and norbornene-based compound has a Mooney viscosity (ML). 1+4 The temperature (100°C) is preferably 20 to 150°C, more preferably 22 to 120°C, and particularly preferably 25 to 90°C. Here, the Mooney viscosity of the copolymer (ML) 1+4 The values ​​(100°C) were measured according to JIS K6300.

[0048] The method for producing the copolymer of cyclopentene and norbornene compound is not particularly limited, but one example is a method of copolymerizing cyclopentene and a norbornene compound represented by the above general formula (1) in the presence of a ring-opening polymerization catalyst.

[0049] The ring-opening polymerization catalyst is not particularly limited as long as it can perform ring-opening copolymerization between cyclopentene and a norbornene-based compound represented by the general formula (1) above, but ruthenium carbene complexes and Group 6 transition metal compounds of the periodic table containing halogen atoms (hereinafter also referred to as "Group 6 transition metal compounds of the periodic table") are preferred. These ring-opening polymerization catalysts may be used individually or in combination of two or more.

[0050] The ruthenium carbene complexes include bis(tricyclohexylphosphine)benzylidene ruthenium dichloride, bis(triphenylphosphine)-3,3-diphenylpropenylidene ruthenium dichloride, bis(tricyclohexylphosphine)t-butylvinylidene ruthenium dichloride, dichloro-(3-phenyl-1H-indene-1-ylidene)bis(tricyclohexylphosphine)ruthenium, bis(1,3-diisopropylimidazoline-2-ylidene)benzylidene ruthenium dichloride, and bis(1,3-dicyclohexylimidazoline-2-ylidene). Examples include (dazoline-2-ylidene)benzylidene ruthenium dichloride, (1,3-dimethylimidazoline-2-ylidene)(tricyclohexylphosphine)benzylidene ruthenium dichloride, (1,3-dimethylimidazolidin-2-ylidene)(tricyclohexylphosphine)benzylidene ruthenium dichloride, bis(tricyclohexylphosphine)ethoxymethylidene ruthenium dichloride, and (1,3-dimethylimidazolidin-2-ylidene)(tricyclohexylphosphine)ethoxymethylidene ruthenium dichloride.

[0051] The aforementioned Group 6 transition metal compounds are compounds having a Group 6 transition metal atom of the periodic table (long-period periodic table, the same applies hereinafter), specifically, compounds having a chromium atom, a molybdenum atom, or a tungsten atom. Compounds having a molybdenum atom or a tungsten atom are preferred, and compounds having a tungsten atom are more preferred from the viewpoint of high solubility in cyclopentene. Specific examples of the aforementioned Group 6 transition metal compounds include molybdenum compounds such as molybdenum pentachloride, molybdenum oxotetrachloride, and molybdenum (phenylimide) tetrachloride; and tungsten compounds such as tungsten hexachloride, tungsten oxotetrachloride, tungsten (phenylimide) tetrachloride, monocatecollate tungsten tetrachloride, bis(3,5-diter-butyl)catecollate tungsten dichloride, and bis(2-chloroetherate) tetrachloride.

[0052] The amount of the ring-opening polymerization catalyst used is typically 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, in terms of the molar ratio of (ring-opening polymerization catalyst: monomer used for copolymerization). When using a Group 6 transition metal compound, the amount of the Group 6 transition metal compound used 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, in terms of the molar ratio of "Group 6 transition metal atom in the ring-opening polymerization catalyst: monomer used for ring-opening polymerization".

[0053] When using the Group 6 transition metal compound of the periodic table as the ring-opening polymerization catalyst, it is preferable to use it in combination with the organoaluminum compound represented by the following general formula (2). The organoaluminum compound acts as a ring-opening polymerization catalyst together with the Group 6 transition metal compound of the periodic table described above. (R 5 ) 3-x Al(OR 6 ) x ... (2) In the above general formula (2), R5 and R 6 are each independently a hydrocarbon group having 1 to 20 carbon atoms, preferably a hydrocarbon group having 1 to 10 carbon atoms. Also, x satisfies 0 < x < 3.

[0054] In the general formula (2) above, R 5 and R 6 Examples 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, n-decyl group; aryl groups such as phenyl group, 4-methylphenyl group, 2,6-dimethylphenyl group, 2,6-diisopropylphenyl group, naphthyl group; and the like.

[0055] Also, in the general formula (2) above, x satisfies 0 < x < 3. That is, in the general formula (2), the composition ratios of R 5 and OR 6 can each take any value within the ranges of 0 < 3 - x < 3 and 0 < x < 3, respectively. From the perspective of enhancing the polymerization activity, it is preferable that x satisfies 0.5 < x < 1.5.

[0056] The organoaluminum compound represented by the general formula (2) above can be synthesized, for example, by reacting a trialkylaluminum with an alcohol as shown in the following general formula (3). (R 5 )3Al + xR<…>​​​​​​​​​​​​​​​​​​​​The amount of the organoaluminum compound used varies depending on the type of organoaluminum compound used, but is preferably 0.1 to 100 moles, more preferably 0.2 to 50 moles, and even more preferably 0.5 to 20 moles, relative to the Group 6 transition metal atoms constituting the Group 6 transition metal compound. If the amount of organoaluminum compound used is too small, the polymerization activity may be insufficient, and if it is too large, side reactions tend to occur more easily during ring-opening polymerization.

[0059] The polymerization reaction may be carried out in a solvent-free environment or in a solution. When copolymerizing in a solution, the solvent used is not particularly limited as long as it is inert in the polymerization reaction and capable of dissolving cyclopentene, norbornene compounds represented by the general formula (1) above, polymerization catalysts, etc. used in copolymerization, but it is preferable to use a hydrocarbon solvent or a halogen solvent. Examples of hydrocarbon solvents 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 halogen solvents include haloalkanes such as dichloromethane and chloroform; and aromatic halogens such as chlorobenzene and dichlorobenzene. These solvents may be used individually or in mixtures of two or more.

[0060] When copolymerizing cyclopentene with a norbornene-based compound represented by the above general formula (1), an olefin compound or diolefin compound may be added to the polymerization reaction system as a molecular weight adjuster to adjust the molecular weight of the resulting copolymer, if necessary. The olefin compound is not particularly limited as long as it is an organic compound having an ethylenically unsaturated bond, and examples 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. In addition, 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, and 2,5-dimethyl-1,5-hexadiene. The amount of olefin and diolefin compounds used as molecular weight adjusters can be appropriately selected according to the molecular weight of the copolymer to be produced, but the molar ratio 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, relative to the monomer used in copolymerization.

[0061] Furthermore, when the copolymer of cyclopentene and norbornene-based compounds has a modifying group at the polymer chain end, it is preferable to use a modifying group-containing olefinic unsaturated hydrocarbon compound as a molecular weight adjuster instead of the olefin or diolefin compounds mentioned above. By using a modifying group-containing olefinic unsaturated hydrocarbon compound, the modifying group can be suitably introduced at the polymer chain end of the copolymer obtained by copolymerization. The modifying group-containing olefinic unsaturated hydrocarbon compound is not particularly limited and can be any compound that has a modifying group and one olefinic carbon-carbon double bond that is metathesis reactive. For example, if it is desired to introduce an oxysilyl group at the polymer chain end of the copolymer, an oxysilyl group-containing olefinic unsaturated hydrocarbon can be present in the polymerization reaction system.

[0062] Examples of the oxysilyl group-containing olefinic unsaturated hydrocarbons include alkoxysilane compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, allylmethoxydimethylsilane, allyltriethoxysilane, allylethoxydimethylsilane, styryltrimethoxysilane, styryltriethoxysilane, styrylethyltriethoxysilane, allyltriethoxysilylmethyl ether, and allyltriethoxysilylmethylethylamine, which introduce a modifying group to only one end (one end) of the polymer chain of the copolymer; vinyltriphenoxysilane, allyltriphenoxysilane, ali Examples include aryloxysilane compounds such as ruphenoxydimethylsilane; asiloxilane 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. Furthermore, modifying groups are introduced to both ends (both terminals) of the polymer chain of the copolymer, such as alkoxysilane compounds like 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 like 2-butene-1,4-di(triphenoxysilane); and 2-butene Examples include acyloxysilane compounds such as -1,4-di(triacetoxysilane); alkylsiloxysilane compounds such as 2-buten-1,4-di[tris(trimethylsiloxy)silane]; arylsiloxysilane compounds such as 2-buten-1,4-di[tris(triphenylsiloxy)silane]; and polysiloxane compounds such as 2-buten-1,4-di(heptamethyltrisiloxane) and 2-buten-1,4-di(undecamethylcyclohexasiloxane).

[0063] The aforementioned olefinic unsaturated hydrocarbon compound containing the modifying group acts not only to introduce the modifying group to the polymer chain ends of the copolymer, but also as a molecular weight adjuster. Therefore, the amount of the olefinic unsaturated hydrocarbon compound containing the modifying group used can be appropriately selected according to the molecular weight of the copolymer to be produced, but the molar ratio with respect to the monomer used in copolymerization 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.

[0064] 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 especially 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 especially preferably less than 80°C. The polymerization reaction time is not particularly limited, but is preferably 1 minute to 72 hours, more preferably 10 minutes to 20 hours.

[0065] The copolymer obtained by the polymerization reaction may optionally contain antioxidants such as phenolic stabilizers, phosphorus-based stabilizers, or sulfur-based stabilizers. The amount of antioxidant added should be determined appropriately depending on its type and other factors. Furthermore, the copolymer may optionally contain a spreading oil. When the copolymer is obtained as a polymerization solution, known recovery methods can be used to recover the copolymer from the polymerization solution. For example, a method can be employed in which the solvent is separated by steam stripping, the solid is filtered off, and then the solid is dried to obtain a solid copolymer.

[0066] The content of the copolymer of cyclopentene and norbornene 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. When the content of the copolymer of cyclopentene and norbornene compound is in the range of 20 to 90 parts by mass per 100 parts by mass of the rubber component, the balance between the low fuel consumption and wear resistance of the rubber composition is further improved, and by applying this rubber composition to a tire, the balance between the low fuel consumption and wear resistance of the tire can be improved.

[0067] -Butadiene rubber- Preferably, the rubber component further contains butadiene rubber (BR). Butadiene rubber has a low glass transition temperature (Tg), and by including butadiene rubber in addition to the copolymer of cyclopentene and norbornene-based compound mentioned above, the fuel efficiency and wear resistance of the rubber composition can be further improved. Therefore, a tire rubber composition containing the copolymer of cyclopentene and norbornene-based compound and butadiene rubber has further improved fuel efficiency and wear resistance, and by applying this rubber composition to a tire, the fuel efficiency and wear resistance of the tire can be further improved.

[0068] When the rubber component includes butadiene rubber, the amount of butadiene rubber is preferably in the range of 10 to 80 parts by mass, and more preferably in the range of 15 to 70 parts by mass, per 100 parts by mass of the rubber component. When the amount of butadiene rubber is in the range of 10 to 80 parts by mass per 100 parts by mass of the rubber component, the balance between the low fuel consumption and abrasion resistance of the rubber composition is further improved.

[0069] -Other rubber- The aforementioned rubber component may further contain other rubbers. Examples of such other rubbers include natural rubber (NR), synthetic isoprene rubber (IR), 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 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.

[0070] (Filler) The tire rubber composition of this embodiment includes a filler. The inclusion of the filler improves the reinforcing properties of the rubber composition.

[0071] The content of the filler is preferably in the range of 5 to 150 parts by mass per 100 parts by mass of the rubber component. If the filler content is 5 parts by mass or more per 100 parts by mass of the rubber component, the wear resistance of the rubber composition is further improved, and if it is 150 parts by mass or less, the fuel efficiency and workability of the rubber composition are further improved. Therefore, a tire rubber composition with a filler content of 5 to 150 parts by mass per 100 parts by mass of the rubber component has further improved workability, fuel efficiency and wear resistance, and by applying this rubber composition to a tire, the fuel efficiency and wear resistance of the tire can be further improved. Furthermore, from the viewpoint of wear resistance, the filler content is more preferably 10 parts by mass or more per 100 parts by mass of the rubber component, and more preferably 20 parts by mass or more. From the viewpoint of fuel efficiency and workability, it is more preferably 120 parts by mass or less, more preferably 100 parts by mass or less, more preferably 80 parts by mass or less, more preferably 70 parts by mass or less, and more preferably 60 parts by mass or less.

[0072] -Recycled Carbon Black- In the tire rubber composition of this embodiment, the filler contains recycled carbon black. Since recycled carbon black is a material derived from recycled resources, incorporating recycled carbon black into the rubber composition can increase the use of sustainable materials in tires to which this rubber composition is applied.

[0073] In this specification, "recycled carbon black" refers to carbon black obtained by recovering from raw materials that are waste materials submitted for recycling. Examples of such waste materials include waste rubber, used tires, and waste oil. Waste rubber refers to all discarded rubber, including not only rubber generated from rubber products but also unwanted scraps generated during the production or repair of rubber products. Examples of scraps include buffing powder and peeling rubber. Buffing powder is fine rubber generated, for example, in the buffing process of retreading tires, where the tread portion remaining on the base tire is scraped off. Peeling rubber is long pieces of rubber, for example, 1 to 2 cm wide, that are peeled off from the surface of rubber products such as tires. Peeling rubber is generated by scraping the surface of rubber products such as tires using a U-shaped or V-shaped knife like a peeler. Furthermore, waste rubber includes not only cross-linked rubber but also unvulcanized rubber. Rubber products include, for example, final products such as tires and rubber hoses, and rubber parts or components at the manufacturing stage of final products. Used tires may include, for example, tires that have been retreaded, tires generated from tire replacement or vehicle scrapping, and End-of-Life Tires (ELTs) that have reached the end of their lifespan, or any other type of tire that has been discarded for any reason. Waste oil is not limited to that generated when plastics and rubber are broken down, but also includes used oils discharged from industry, such as animal and vegetable oils, lubricating oils, insulating oils, and cutting oils. Among these, waste oil that does not contain any non-organic components, such as those derived from silicone rubber or polyvinyl chloride, is preferable. Furthermore, waste oil that contains carbon black or rubber containing carbon black is preferable. "Recycled carbon black" is different from carbon black that is not recycled, which is manufactured directly using hydrocarbons such as petroleum, natural gas, and coal as raw materials. Furthermore, "used" here includes not only carbon black that has been discarded after actual use, but also carbon black that was manufactured but discarded without actually being used.

[0074] Furthermore, it is preferable that the recycled carbon black is obtained by thermal decomposition of a vulcanized rubber product containing carbon black. Recycled carbon black obtained by thermal decomposition of a vulcanized rubber product containing carbon black is readily available because a large amount of vulcanized rubber products containing carbon black exist and it can be easily obtained by thermal decomposition. Moreover, it is preferable that the recycled carbon black is obtained from the solid residue generated by the thermal decomposition of the vulcanized rubber product containing carbon black. When a rubber product containing carbon black is thermally decomposed, solid residue and volatile components (oil) are obtained, and recycled carbon black can be recovered from either. Furthermore, when recovering carbon black from volatile components, it is possible to recover oil with a specific gravity suitable for carbon black production and use it to produce carbon black using existing carbon black production methods (for example, Japanese Patent Publication No. 2015-520259). In this case, unlike carbon black recovered from solid residues, there are advantages such as the absence of impurities and the absence of mixtures of different grades. In addition, in the production of low-environmental-impact carbon black, there are various options other than using oil obtained by recovering volatile components from the aforementioned rubber pyrolysis, such as using vegetable oil or oil derived from waste plastics. However, edible resources such as vegetable oil present challenges in securing sufficient quantities due to other uses such as food, and the environmental impact associated with the expansion of cultivated land must also be considered. Similarly, oil derived from waste plastics is also used for other purposes such as horizontal recycling of plastics, so supply issues are also likely to arise. On the other hand, when using vulcanized rubber products, particularly volatile components (oils) produced by the thermal decomposition of tires, the tire industry has a system in place to continue using existing materials. This allows for the continued use of existing materials, reducing the consumption of new materials in new tire manufacturing and contributing to a reduction in the industry's environmental impact. The grades of carbon black mentioned above are not particularly limited, but include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc.

[0075] The solid residue obtained by thermally decomposing waste materials such as used rubber and used tires contains ash in addition to carbon black. The ash originates from non-volatile components contained in rubber and tires. Therefore, the recycled carbon black obtained from this solid residue has a relatively low carbon black content. On the other hand, considering the various physical properties required for tires manufactured using recycled carbon black, a higher carbon content in recycled carbon black is preferable. In the recycled carbon black, the carbon content 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 in the recycled carbon black is preferably 97% by mass or less. Note that the carbon content does not include adsorbed water.

[0076] The aforementioned ash content specifically includes zinc oxide, zinc sulfide, silica, iron compounds (iron oxide), calcium oxide, aluminum oxide, magnesium oxide, and the like. In the case of recycled carbon black produced from solid residue obtained by thermal decomposition of waste, a certain amount of ash remains even after various processes to remove it. In this embodiment, the presence of ash in recycled carbon black is permitted. In one embodiment, the lower limit of the ash content of the recycled carbon black may be 0.5% by mass.

[0077] Furthermore, the recycled carbon black can be obtained from the pyrolysis process of used pneumatic tires. For example, European Patent Application Publication No. 3427975, referring to "Rubber Chemistry and Technology," Vol. 85, No. 3, pp. 408-449 (2012), particularly pp. 438, 440, and 442, states that it can be obtained by the 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 usually lacks functional groups on its surface, as referred to in paragraph

[0004] of Japanese Patent Publication No. 6856781 (Comparison of Surface Morphology and Chemistry of Pyrolysis Carbon Black and Commercial Carbon Black, Powder Technology 160 (2005) 190-193).

[0078] The recycled carbon black may lack functional groups on its surface, or it may have been treated to include functional groups on its surface. 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. 3173251, carbon black obtained from a thermal decomposition process is treated with potassium permanganate under acidic conditions to obtain carbon black containing hydroxyl groups and / or carboxyl groups on its surface. In addition, in Japanese Patent Publication No. 6856781, carbon black obtained from a thermal decomposition process is treated with an amino acid compound containing at least one thiol group or disulfide group to obtain carbon black with an activated surface. The recycled carbon black according to this embodiment also includes carbon black that has been treated to include functional groups on its surface.

[0079] Furthermore, for the thermal decomposition of cross-linked rubber products (vulcanized rubber products) such as used tires, one example is a thermal decomposition method at a temperature of 650°C or higher.

[0080] The cross-linked rubber products used in the aforementioned decomposition may be grouped by the type of rubber component they contain beforehand, and the decomposition process may be carried out for each group separately. Alternatively, they may be grouped by the type of filler they contain beforehand (for example, the type of carbon black, the type of silica, the mixing ratio of carbon black and silica, etc.), and the decomposition process may be carried out for each group separately. Furthermore, they may be grouped by both the type of rubber component and the type of filler, and the decomposition process may be carried out for each group separately. When the decomposition process is carried out for each group in this way, recycled carbon black with more uniform physical properties can be obtained, and when it is again incorporated into the rubber component, a rubber composition with better performance can be obtained.

[0081] Furthermore, if the cross-linked rubber product used in the decomposition is derived from a tire, it may be grouped in advance by tire type (for example, for passenger cars, trucks and buses, heavy vehicles such as off-road vehicles, aircraft, agricultural vehicles, etc.) and then the decomposition process may be carried out for each group. Alternatively, it may be grouped in advance by tire component (for example, tread rubber, sidewall rubber, bead rubber, steel cord coated rubber, organic fiber coated rubber, pad rubber, cushion rubber, etc.) and then the decomposition process may be carried out for each group. In addition, it may be possible to group by tire type and by tire component and then carry out the decomposition process for each group. When the decomposition process is carried out for each group in this way, recycled carbon black with more uniform physical properties can be obtained, and when it is again blended into the rubber component, a rubber composition with better performance can be obtained.

[0082] The recycled carbon black can also be prepared in accordance with the method for preparing paste as a measurement sample in grind gauge measurement described in JIS K5101-1-5, and when measured in accordance with JIS K5400, it can have three or more lines with a length of 10 mm or more, and the particle size of the third largest particle among the particles that give rise to such lines of 10 mm or more is 20 μm or less. In the aforementioned grind gauge measurement, it is preferable to use a grind gauge with a range of 0 to 25 μm. From the viewpoint of the durability of the rubber composition, it is important whether the particle size of the third largest particle in the recycled carbon black being measured is 20 μm or less. Therefore, from the viewpoint of accurately measuring particle sizes around 20 μm, and from the viewpoint of ease of measurement, it is preferable to use a grind gauge with a range of 0 to 25 μm. Note that a grind gauge with an upper limit of the range greater than 20 μm can also be used, as it is possible to determine whether the particle size of the third largest particle is 20 μm or less. Furthermore, when used for other purposes (performance other than the durability of the rubber composition containing recycled carbon black), the range of the grind gauge used can be appropriately selected according to the purpose.

[0083] As described above, JIS K5101-1-5 describes a method for preparing a paste of recycled carbon black as a measurement sample in grind gauge measurement. In this embodiment, it is preferable to prepare the paste of recycled carbon black in accordance with JIS K5101-1-5 as a measurement sample for measurement using a grind gauge. By preparing the paste of recycled carbon black in accordance with JIS K5101-1-5, the accuracy of evaluating the quality of recycled carbon black can be further improved. In one embodiment, the accuracy of grind gauge measurement can be further improved by appropriately adjusting the viscosity of the paste. In one embodiment, it is preferable to prepare a paste (measurement sample) containing recycled carbon black by blending recycled carbon black and zinc oxide with epoxidized soybean oil. Here, the blending ratio of the paste is not particularly limited, but it is preferable to use about 8 to 12 g of recycled carbon black and about 160 to 200 g of zinc oxide per 100 mL of epoxidized soybean oil.

[0084] Furthermore, when preparing the recycled carbon black paste in accordance with JIS K5101-1-5, it is preferable to apply a load of 0.4 to 0.5 kN and rotate the glass plate at a speed of 90 to 110 r / min, from the viewpoint of improving evaluation accuracy.

[0085] In this embodiment, recycled carbon black having three or more lines of 10 mm or longer in length, as measured by a grind gauge, and the particle size of the third largest particle among those particles having a length of 10 mm or longer being 20 μm or less, can be produced by various methods. For example, recycled carbon black with a particle size of 20 μm or less can be produced by further grinding for a longer period or increasing the grinding intensity of recycled carbon black produced by a general method from recycled waste.

[0086] The aforementioned recycled carbon black has a nitrogen adsorption specific surface area of ​​40-100 m² as determined by the BET method. 2 It is preferable that the amount be / g, and 50-90m 2 It is more preferable that the amount be / g, which is 55-75m 2 It is particularly preferable that the value be / g. Herein, in this specification, the nitrogen adsorption specific surface area of ​​recycled carbon black by the BET method is the statistical thickness specific surface area (STSA), which is determined according to ASTM D6556.

[0087] The recycled carbon black preferably has a pH of 4 to 12, more preferably 5 to 11, and particularly preferably 6 to 10. Herein, in this specification, the pH of recycled carbon black is determined according to ASTM D1512.

[0088] The recycled carbon black preferably has a toluene color transmission rate of 60% or more, more preferably 70% or more, and particularly preferably 80% or more. Herein, in this specification, the toluene staining transmittance of recycled carbon black is determined according to ASTM D1618.

[0089] The recycled carbon black preferably has a heating loss of 3% by mass or less at 125°C, more preferably 2.5% by mass or less, and particularly preferably 2% by mass or less. Herein, in this specification, the heating loss of recycled carbon black at 125°C is determined according to ASTM D1509.

[0090] 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.

[0091] The recycled carbon black preferably has a residue of 20 ppm by mass or less after sieving with a 35 mesh, more preferably 15 ppm by mass or less, and particularly preferably 10 ppm by mass or less. Herein, in this specification, the 35-mesh sieve residue of recycled carbon black is determined according to ASTM D1514.

[0092] The recycled carbon black preferably has a residue of 1,000 ppm by mass or less after sieving with a 325 mesh (44 μm), more preferably 700 ppm by mass or less, and particularly preferably 300 ppm by mass or less. Herein, in this specification, the 325-mesh (44 μm) sieve residue of recycled carbon black is determined according to ASTM D1514.

[0093] 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, in this specification, the pellet hardness of recycled carbon black is determined according to ASTM D5230.

[0094] The recycled carbon black preferably has a pelletized 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, in this specification, the amount of recycled carbon black pellets is determined according to ASTM D1508.

[0095] The recycled carbon black preferably has a particle size (D97) of 25 μm or less, more preferably 15 μm or less, and particularly preferably 10 μm or less. In this specification, the particle size (D97) of recycled carbon black is determined using a laser diffraction particle size analyzer, with a refractive index of 1.33 for water and 1.75 for the filler.

[0096] The recycled carbon black preferably contains 50% or more by volume of particles 5 μm or smaller, more preferably 70% or more by volume, and particularly preferably 80% or more by volume.

[0097] 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 various physical properties of rubber products to which the rubber composition is applied can be improved. Herein, in this specification, the ash content of recycled carbon black is determined according to ASTM D8474·D1506.

[0098] The recycled carbon black preferably has an oil adsorption capacity (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, in this specification, the OAN of recycled carbon black is determined according to ASTM D2414.

[0099] The recycled carbon black preferably has a compressed oil adsorption capacity (COAN) 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, in this specification, the COAN of recycled carbon black is determined according to ASTM D3493.

[0100] Commercially available recycled carbon black can be used. Examples of such commercially available products include "PB365" manufactured by Enrestec. PB365 is recycled carbon black produced by the thermal decomposition of used tires, and has a nitrogen adsorption specific surface area of ​​73.6 m² according to the BET method. 2 It is [value] / g and also contains approximately 17% by mass of ash.

[0101] The recycled carbon black content 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, even 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. When the recycled carbon black content is 5 parts by mass or more per 100 parts by mass of the rubber component, it has a significant effect on improving the ratio of sustainable materials in the tire to which the rubber composition is applied, and when it is 50 parts by mass or less, the fracture resistance of the rubber composition can be maintained more reliably.

[0102] The proportion of recycled carbon black in the filler is preferably in the range of 10 to 100% by mass. When the proportion of recycled carbon black in the filler is 10% by mass or more, the effect of increasing the utilization rate of sustainable materials is greatly enhanced, as is the extent to which the workability, fuel efficiency, and fracture characteristics of the rubber composition are improved. Therefore, a tire rubber composition in which the proportion of recycled carbon black in the filler is 10 to 100% by mass has a high utilization rate of sustainable materials, as well as further improvements in workability, fuel efficiency, and fracture characteristics. By applying this rubber composition to a tire, the fuel efficiency and wear resistance of the tire can be further improved. Furthermore, from the viewpoint of the utilization rate of sustainable materials, the workability, fuel efficiency, and fracture characteristics of the rubber composition, the proportion of recycled carbon black in the filler is more preferably 20% by mass or more, and even more preferably 30% by mass or more.

[0103] -Other fillers- The filler may include, in addition to the recycled carbon black described above, other fillers. Examples of such other fillers include carbon black other than recycled carbon black, silica, clay, talc, calcium carbonate, aluminum hydroxide, etc. Among these, carbon black other than recycled carbon black is preferred as the other filler. The proportion of fillers other than recycled carbon black in the filler is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or more.

[0104] (others) In addition to the rubber components and fillers described above, the tire rubber composition of this embodiment may optionally contain various components commonly used in the rubber industry, such as silane coupling agents, antioxidants, hardened fatty acids, zinc oxide (zinc oxide), tackifiers, vulcanization accelerators, vulcanizing agents, etc., selected as appropriate within a range that does not impair the purpose of the present invention. Commercially available products can be suitably used as these compounding agents.

[0105] Examples of the aforementioned antioxidants include N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6C) and 2,2,4-trimethyl-1,2-dihydroquinoline polymer (TMDQ). These antioxidants may be used individually or in combination of two or more. There are no particular restrictions on the content of the antioxidant, but it 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.

[0106] Examples of the hardened fatty acid include stearic acid. 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.

[0107] The content of the zinc oxide (zinc oxide) is not particularly limited, but is preferably in the range of 0.1 to 10 parts by mass, and more preferably 1 to 8 parts by mass, per 100 parts by mass of the rubber component.

[0108] Examples of the tackifier include rosin resins, terpene resins, petroleum resins, phenolic resins, coal resins, and xylene resins, among which petroleum resins are preferred. Examples of petroleum resins include C5 resins, C5-C9 resins, C9 resins, and dicyclopentadiene resins. There are no particular restrictions on the content of the tackifier, but it 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.

[0109] Examples of the vulcanization accelerator include sulfenamide-based vulcanization accelerators, guanidine-based vulcanization accelerators, thiazole-based vulcanization accelerators, thiram-based vulcanization accelerators, and dithiocarbamate-based vulcanization accelerators. These vulcanization accelerators may be used individually or in combination of two or more. There are no particular restrictions on the content of the vulcanization accelerator, but it is preferably in the range of 0.1 to 5 parts by mass, and more preferably in the range of 0.2 to 4 parts by mass, per 100 parts by mass of the rubber component.

[0110] Examples of the vulcanizing agent include sulfur. The content of the vulcanizing agent is preferably in the range of 0.1 to 6 parts by mass, and more preferably in the range of 0.5 to 3 parts by mass, as sulfur, per 100 parts by mass of the rubber component.

[0111] (Method for manufacturing rubber composition for tires) The method for producing the aforementioned tire rubber composition is not particularly limited, but for example, it can be produced by mixing the rubber components and fillers described above with various components as needed, and then kneading, heating, extruding, etc. Furthermore, the obtained rubber composition can be vulcanized to produce vulcanized rubber.

[0112] There are no particular restrictions on the mixing conditions, and various conditions such as the input volume of the mixing device, the rotation speed of the rotor, the ram pressure, as well as the mixing temperature, mixing time, and the type of mixing device can be appropriately selected according to the purpose. Examples of mixing devices include Banbury mixers, intermixes, kneaders, and rolls, which are commonly used for mixing rubber compositions.

[0113] There are no particular restrictions on the heat treatment conditions, and various conditions such as heat treatment temperature, heat treatment time, and heat treatment equipment can be appropriately selected according to the purpose. Examples of such heat treatment equipment include heat treatment roll machines commonly used for heat treatment of rubber compositions.

[0114] There are no particular restrictions on the extrusion conditions, and various conditions such as extrusion time, extrusion speed, extrusion equipment, and extrusion temperature can be appropriately selected according to the purpose. Examples of extrusion equipment include extruders typically used for extruding rubber compositions. The extrusion temperature can be determined as appropriate.

[0115] There are no particular restrictions on the apparatus, method, and conditions for performing the vulcanization, and they can be appropriately selected according to the purpose. Typical vulcanization apparatuses include molding vulcanizers using molds, which are commonly used for vulcanizing rubber compositions. The vulcanization temperature is typically around 100-190°C.

[0116] <Tires> The tire of this embodiment is characterized by containing the above-described tire rubber composition. Because the tire of this embodiment contains the above-described tire rubber composition, it is possible to achieve productivity, low fuel consumption, and wear resistance while applying sustainable materials. The part of the tire to which the rubber composition is applied is the tread rubber.

[0117] 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 undergone a pre-vulcanization process, and then further vulcanizing it. The tire of this embodiment is preferably a pneumatic tire, and as the gas to fill the pneumatic tire, in addition to ordinary air or air with adjusted oxygen partial pressure, an inert gas such as nitrogen, argon, or helium can be used. [Examples]

[0118] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way to the following examples.

[0119] <Method for synthesizing copolymers> 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-indene-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 stopped by adding an excess of vinyl ethyl ether. The polymerization solution was poured into a large excess of methanol containing 2,6-di-t-butyl-p-cresol (BHT), 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.

[0120] <Analysis of copolymers> The molecular weight of the synthesized copolymer and the proportion of structural units derived from each monomer were measured using the method described below. The results are shown in Table 1.

[0121] (1) Weight average molecular weight (Mw) A gel permeation chromatography (GPC) system "HLC-8220" (manufactured by Tosoh Corporation) was used, with two H-type columns "HZ-M" (manufactured by Tosoh Corporation) connected in series, using tetrahydrofuran as the solvent, and measurements were taken 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.

[0122] (2) The proportion of structural units derived from each monomer The proportion of structural units derived from each monomer constituting the copolymer is 1 This was determined from 1H-NMR spectroscopy measurements.

[0123] [Table 1]

[0124] <Preparation of rubber composition> Each component was blended and kneaded according to the formulation shown in Table 2 to prepare the rubber compositions for the Examples and Comparative Examples.

[0125] In addition to the components shown in Table 2, each rubber composition was further formulated with the following additives per 100 parts by mass of rubber component: 2 parts by mass of hardened fatty acid, 3.5 parts by mass of zinc oxide, 2.5 parts by mass of antioxidants (total amount of two types), 1 part by mass of resin, 1.4 parts by mass of sulfenamide-based vulcanization accelerator, and 1.05 parts by mass of sulfur.

[0126] <Evaluation of rubber compositions> The obtained rubber compositions were evaluated for workability, toughness, filler dispersibility, fuel efficiency, and abrasion resistance using the following methods. The results are shown in Table 2.

[0127] (3) Workability The dynamic storage (shear) modulus G' was measured using the unvulcanized viscoelastic device "RPA2000 (manufactured by ALPHA TECHNOLOGIES)" under conditions of a temperature of 130°C, a strain (torsion angle) of 1°, and a frequency of 100 cpm. The evaluation results were indexed, with the reciprocal of the value from Comparative Example 1 set to 100. A larger index value indicates lower viscosity of the unvulcanized rubber and better workability.

[0128] (4) Toughness Vulcanized rubber was processed into ring-shaped test pieces, and tensile tests were performed at 25°C in accordance with JIS K6251:2017 to measure elongation at break (Eb) and tensile stress at break (TSb). Toughness (TF) was calculated using the following formula. The evaluation results were indexed with the value of Comparative Example 1 set to 100. A higher index value indicates that the vulcanized rubber has superior rigidity and good abrasion resistance. Toughness (TF) = Elongation at break (Eb) × Tensile stress at break (TSb)

[0129] (5) Dispersibility of fillers Viscoelasticity measurements were performed using a viscoelasticity measuring device (TA Instruments) at a temperature of 50°C and a frequency of 15Hz. The values ​​of G' (10%G') at a strain of 10% and G' (0.1%G') at a strain of 0.1% were measured, and ΔG' was calculated using the following formula. The evaluation results were indexed with the value of Comparative Example 1 set to 100. A larger index indicates superior dispersibility of the filler and better wear resistance. ΔG'=0.1%G'-10%G'

[0130] (6) Fuel efficiency The loss tangent (tanδ) of test specimens prepared from the obtained rubber composition was measured using a viscoelasticity measuring instrument (TA Instruments) under conditions of 50°C, 10% strain, and 15Hz frequency. The modulus (M50) [MPa] of the test specimens at 50% strain was also measured at room temperature. The evaluation results were indexed by setting the reciprocal of tanδ / M50 for Comparative Example 1 to 100. A larger index value indicates superior fuel efficiency.

[0131] (7) Abrasion resistance In accordance with JIS K 6264-2:2005, a Lambourn wear tester manufactured by Ueshima Seisakusho was used to measure the amount of wear at room temperature with sandpaper attached to the abrasive wheel and a slip ratio of 12%. The evaluation results were indexed with the reciprocal of the wear amount of Comparative Example 1 set to 100. A larger index value indicates less wear and superior wear resistance.

[0132] [Table 2]

[0133] *1 NR: Natural rubber *2 BR: Butadiene rubber, manufactured by UBE Elastomers, product name "BR150L" *3 Copolymer: A copolymer of cyclopentene synthesized by the above method and a norbornene-based compound. *4 Carbon Black 1: CTAB adsorption specific surface area is 130 m² 2 Unused carbon black, N330, / g *5 Carbon Black 2: CTAB adsorption specific surface area is 82 m² 2 Unused carbon black, N330, / g *6 Carbon Black 3: Recycled carbon black, manufactured by Enrestec, product name "PB365"

[0134] As shown in Table 2, for the rubber compositions of Comparative Examples 1 to 3, which do not contain a copolymer of cyclopentene and norbornene compounds, replacing some of the unused carbon black with recycled carbon black worsens workability and significantly deteriorates abrasion resistance.

[0135] On the other hand, for the rubber compositions of Comparative Examples 3, 4, and 1, in which the rubber component is a copolymer of cyclopentene and norbornene-based compounds, it can be seen that workability and fuel efficiency are improved by replacing a portion of the unused carbon black with recycled carbon black.

[0136] Furthermore, as can be seen from the comparison between Comparative Example 1 and Comparative Example 4, and between Comparative Example 2 and Comparative Example 5, the inclusion of a copolymer of cyclopentene and norbornene-based compounds in the rubber component improves abrasion resistance. Therefore, it can be seen that the rubber composition of Example 1 can suppress deterioration of abrasion resistance even when some of the unused carbon black is replaced with recycled carbon black.

[0137] These results show that, according to the present invention, by combining a copolymer of cyclopentene and norbornene-based compounds with recycled carbon black, it is possible to achieve both workability, low fuel consumption, and abrasion resistance in the rubber composition while applying sustainable materials.

[0138] Furthermore, according to the present invention, it is found that by combining a copolymer of cyclopentene and norbornene-based compounds with recycled carbon black, the dispersibility of the filler is improved, and the toughness (fracture properties) of the rubber composition is also improved.

[0139] [Contribution to the United Nations-led Sustainable Development Goals (SDGs)] The SDGs have been proposed to realize a sustainable society. One embodiment of the present invention is considered to be a technology that can contribute to "No. 7 Affordable and Clean Energy," "No. 12 Responsible Consumption and Production," and "No. 13 Climate Action."

Claims

1. It contains rubber components and fillers. The aforementioned rubber component is cyclopentene and the following general formula (1): 【Chemistry 1】 [In the formula, R １ ~R ４ Each of these 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, and R ２ and R ３ These may be bonded together to form a ring, and m is an integer from 0 to 2. The copolymer includes a norbornene compound represented by [ ]. A rubber composition for tires, characterized in that the filler contains recycled carbon black.

2. The tire rubber composition according to claim 1, wherein the content of the copolymer of cyclopentene and norbornene compound is 20 to 90 parts by mass per 100 parts by mass of the rubber component.

3. The rubber composition for tires according to claim 1, wherein the copolymer of cyclopentene and norbornene compound has a weight-average molecular weight (Mw) of 200,000 to 1,000,000.

4. The tire rubber composition according to claim 1, wherein the copolymer of cyclopentene and norbornene-based compound has a content of cyclopentene-derived structural units of 20 to 75% by mass.

5. The tire rubber composition according to claim 1, wherein the copolymer of cyclopentene and norbornene-based compound has a content of 10 to 60% by mass of structural units derived from 2-norbornene.

6. The tire rubber composition according to claim 1, wherein the copolymer of cyclopentene and norbornene-based compound has a content of dicyclopentadiene-derived structural units of 10 to 60% by mass.

7. The tire rubber composition according to claim 1, wherein the content of the filler is 5 to 150 parts by mass per 100 parts by mass of the rubber component.

8. The tire rubber composition according to claim 1, wherein the proportion of recycled carbon black in the filler is 10 to 100% by mass.

9. The tire rubber composition according to claim 1, wherein the rubber component further comprises butadiene rubber.

10. A tire characterized by comprising the tire rubber composition described in any one of claims 1 to 9.

Images