Rubber composition and tires

Abstract

To provide a rubber composition and tire with excellent heat resistance. [Solution] The present invention relates to a rubber composition comprising a rubber component containing an epoxidized diene rubber, a pyridine compound represented by the following general formula (1), and a carboxylic acid compound with a valency of 2 or higher. [C1] TIFF2026068251000007.tif35156(In formula (1), R bonded to the pyridine ring) 1 ~R 5 R represents a hydrogen atom or a monovalent organic group, either identical or different. 1 ~R 5 They may be bonded to each other, or they may form a ring structure.

Description

Technical Field

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

Background Art

[0002] Various performances are required for tires, and performances such as low fuel consumption are required (see Patent Document 1). In addition, improvement in heat resistance and the like is also required.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to solve the above problems and provide a rubber composition and a tire having excellent heat resistance.

Means for Solving the Problems

[0005] The present invention relates to a rubber composition containing an epoxidized diene rubber, a pyridine compound represented by the following general formula (1), and a polyvalent carboxylic acid compound.

[0006]

Chemical Formula

[0007] In the above formula (1), R bonded to the pyridine ring 1 ~R 5 represent the same or different hydrogen atoms or monovalent organic groups. R 1 ~R 5 may be bonded to each other or may form a ring structure.

Effects of the Invention

[0008] The present invention provides a rubber composition comprising a rubber component containing an epoxidized diene rubber, a pyridine compound represented by the above general formula (1), and a divalent or higher carboxylic acid compound, thereby improving heat resistance. [Modes for carrying out the invention]

[0009] The above rubber composition is characterized by containing a rubber component including an epoxidized diene rubber, a pyridine compound represented by the above general formula (1), and a divalent or higher carboxylic acid compound.

[0010] The mechanism by which the above rubber composition produces the aforementioned effects is not entirely clear, but it can be inferred as follows. It is believed that ionic bonds and / or hydrogen bonds can be formed by using a rubber component containing an epoxidized diene rubber, a pyridine compound represented by the above general formula (1), and a divalent or higher carboxylic acid compound in combination. In particular, it is thought that the reaction is initiated by the reaction between the epoxy moiety in the rubber and the pyridine compound in the initial stage. However, a wide range of substituents can be introduced into the pyridine compound, and the reactivity of the pyridine compound can be easily controlled by the type of substituent. Since ionic bonds and hydrogen bonds are reversible bonds, they can be reformed even if they are broken by heat. Therefore, it is presumed that the heat resistance can be improved by using the above rubber composition containing such components in combination.

[0011] The above rubber composition contains rubber components. Here, the rubber component is a component that contributes to crosslinking, and generally, it is a polymer with a weight-average molecular weight (Mw) of 10,000 or more that is not extracted by acetone. The rubber component is in a solid state at 1 atmosphere and room temperature (25°C).

[0012] The weight-average molecular weight of the above rubber component is preferably 50,000 or more, more preferably 150,000 or more, even more preferably 200,000 or more, particularly preferably 270,000 or more, and also preferably 2,000,000 or less, more preferably 1,500,000 or less, and even more preferably 1,000,000 or less. When it is within the above range, the effect tends to be better obtained.

[0013] In this specification, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) can be determined by converting the measured values ​​obtained by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation) to standard polystyrene equivalents.

[0014] The above rubber component may be either unmodified rubber or modified rubber. Examples of modified rubbers include rubbers having functional groups that interact with fillers such as silica. For example, end-modified rubber (end-modified rubber having the functional group at the end) is obtained by modifying at least one end of the rubber with a compound (modifier) ​​having the functional group; main-chain modified rubber having the functional group in the main chain; main-chain end-modified rubber having the functional group in both the main chain and the end (for example, main-chain end-modified rubber having the functional group in the main chain and at least one end modified with the modifier); and end-modified rubber that has been modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule, and into which hydroxyl groups or epoxy groups have been introduced.

[0015] Examples of the above functional groups include amino groups, amide groups, silyl groups, alkoxysilyl groups, isocyanate groups, imino groups, imidazole groups, urea groups, ether groups, carbonyl groups, oxycarbonyl groups, mercapto groups, sulfide groups, disulfide groups, sulfonyl groups, sulfinyl groups, thiocarbonyl groups, ammonium groups, imide groups, hydrazo groups, azo groups, diazo groups, carboxyl groups, nitrile groups, pyridyl groups, alkoxy groups, hydroxyl groups, oxy groups, epoxy groups, and the like. These functional groups may have substituents. Among these, amino groups (preferably amino groups in which the hydrogen atoms of the amino group are substituted with C1-C6 alkyl groups), alkoxy groups (preferably alkoxy groups having C1-C6), and alkoxysilyl groups (preferably alkoxysilyl groups having C1-C6) are preferred.

[0016] The above rubber composition contains epoxidized diene rubber as a rubber component. The above-mentioned epoxidized diene rubbers are not particularly limited and include, for example, epoxidized natural rubber (ENR), epoxidized isoprene rubbers such as epoxidized isoprene rubber, epoxidized butadiene rubber, epoxidized butadiene acrylonitrile rubber, epoxidized styrene-butadiene rubber, and epoxidized isoprene-butadiene rubber. The epoxidized diene rubbers may be used alone or in combination of two or more types.

[0017] The epoxidized diene rubber mentioned above is not particularly limited; for example, commercially available products such as ENR25 or ENR50 from Kumpulan Guthrie, or diene rubber that has been epoxidized may also be used. The epoxidization of diene rubber can be carried out in accordance with the epoxidization of natural rubber.

[0018] Methods for epoxidizing natural rubber include, for example, the chlorhydrin method, direct oxidation method, hydrogen peroxide method, alkyl hydroperoxide method, and peracid method (Japanese Patent Publication No. 4-26617, Japanese Patent Application Publication No. 2-110182, British Patent No. 2113692, etc.). Examples of the peracid method include reacting natural rubber with organic peracids such as peracetic acid or performic acid. By adjusting the amount of organic peracid and the reaction time, epoxidized natural rubber with various epoxidation rates can be prepared. The natural rubber to be epoxidized is not particularly limited; for example, SIR20, RSS#3, TSR20, deproteinized natural rubber (DPNR), and high-purity natural rubber, which are common in the tire industry, can be used.

[0019] Among the above epoxidized diene rubbers, epoxidized isoprene rubber and epoxidized butadiene rubber are preferred from the viewpoint of obtaining better effects, epoxidized isoprene rubber is more preferred, and epoxidized natural rubber is even more preferred.

[0020] When epoxidized isoprene rubber is used as the epoxidized diene rubber mentioned above, the mechanism by which the greater effect is obtained is not clear, but by using epoxidized isoprene rubber, only pyridine compounds can selectively react with the epoxy moieties in the epoxidized isoprene rubber. The epoxy moieties of isoprene rubber have a methyl group adjacent to the epoxy moiety, making them less reactive with nucleophiles. Therefore, by using pyridine compounds, other reactive reagents do not react, and only the pyridine compounds can react, which is presumed to significantly improve heat resistance.

[0021] The epoxidation rate of the above-mentioned epoxidized diene rubber is preferably 15 mol% or more, more preferably 20 mol% or more, and even more preferably 25 mol% or more. On the other hand, the epoxidation rate is preferably 75 mol% or less, more preferably 60 mol% or less, and even more preferably 50 mol% or less. When the rate is within the above range, a better effect tends to be obtained. In this specification, the epoxidation rate is the ratio (mol%) of the number of epoxidized double bonds to the total number of double bonds in the rubber before epoxidation for epoxidized diene rubbers, and can be measured using an NMR spectrometer of the JNM-ECA series manufactured by JEOL Ltd.

[0022] In the above rubber composition, the content of the epoxidized diene rubber in 100% by mass of the rubber component is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more, and may be 100% by mass. When the content is within the above range, a better effect tends to be obtained.

[0023] The above rubber composition may contain rubber components other than the above-mentioned epoxidized diene rubber. Other rubber components besides the epoxidized diene rubbers mentioned above include, for example, non-epoxidized diene rubbers. Examples of non-epoxidized diene rubbers include non-epoxidized isoprene rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), and polynorbornene rubber. Non-diene rubbers such as butyl rubber, hydrogenated nitrile rubber, ethylene-propylene rubber, silicone rubber, polyethylene chloride rubber, fluororubber, acrylic rubber, and hydrin rubber are also included. These may be used individually or in combination of two or more. Furthermore, these rubber components may be subjected to modification treatment or hydrogenation treatment, and stretched rubbers, which have been stretched with oil, resin, or liquid rubber components, may also be used. In particular, from the viewpoint of obtaining better effects, it is preferable to include at least one of isoprene-based rubber, BR, or SBR that is not epoxidized.

[0024] The raw materials (monomers) for synthetic rubbers such as IR, SBR, and BR may be derived from underground resources such as petroleum and natural gas, or they may be recycled from rubber products such as tires or non-rubber products such as polystyrene. The monomers obtained by recycling (recycled monomers) are not particularly limited, but examples include recycled polyisoprene, recycled butadiene, and recycled aromatic vinyl. Examples of butadiene include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl include styrene, but are not particularly limited. In particular, it is preferable to use recycled polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and / or recycled styrene (recycled styrene) as raw materials.

[0025] The method for producing recycled monomer is not particularly limited, and for example, it can be synthesized from recycled naphtha obtained by decomposing rubber products such as tires. Furthermore, the method for producing recycled naphtha is not particularly limited, and for example, rubber products such as tires may be decomposed under high temperature and pressure, decomposed by microwaves, or extracted after mechanical grinding.

[0026] Furthermore, the raw materials (monomers) of synthetic rubbers such as IR, SBR, and BR may be derived from biomass. In this specification, biomass refers to substances derived from natural resources such as plants. Biomass is not particularly limited, but examples include agricultural, forestry, and fishery products, sugars, wood chips, plant residues after obtaining useful components, plant-derived ethanol, and biomass naphtha.

[0027] The biomass-derived monomers (biomass monomers) are not particularly limited, and examples include biomass-derived butadiene and biomass-derived aromatic vinyls. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl is not particularly limited, and examples include styrene. Further, the method for producing the biomass monomer is not particularly limited, and examples include those by biological and / or chemical and / or physical conversion of animals and plants. Fermentation by microorganisms is typical as the biological conversion, and examples of the chemical and / or physical conversion include those by a catalyst, by high heat, by high pressure, by electromagnetic waves, by a critical liquid, and combinations thereof.

[0028] The polymers synthesized from the biomass monomer components (biomass polymers) are not particularly limited, and examples include polybutadiene rubber synthesized from biomass-derived butadiene, and aromatic vinyl / butadiene copolymers synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyls. Examples of the aromatic vinyl / butadiene copolymer include styrene butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0029] Whether the raw material of the polymer is derived from biomass can be determined by pMC (percent Modern Carbon) measured in accordance with ASTM D6866-10.

[0030] pMC is the ratio of the 14 C concentration of the sample to the 14 C concentration of the standard modern carbon (modern standard reference), and is a value used as an index indicating the biomass ratio of a compound. The significance of this value will be described below.

[0031] In one mole (6.02 × 10 23 pieces) of carbon atoms, there are about 6.02 × 10 11 pieces, which is about one trillionth of ordinary carbon atoms, of 14C exists. 14 Carbon dioxide is called a radioactive isotope, and its half-life is 5730 years, decreasing regularly. It takes 226,000 years for all of them to decay. Therefore, in fossil fuels such as coal, oil, and natural gas, which are thought to have been fixed for more than 226,000 years after atmospheric carbon dioxide was taken in by plants, etc., it was initially contained within these materials. 14 All elements of C have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas are no longer viable. 14 It contains absolutely no element C. Therefore, chemical substances produced using these fossil fuels as raw materials also contain C. 14 It contains absolutely no element C.

[0032] on the other hand, 14 C is continuously produced when cosmic rays undergo nuclear reactions in the atmosphere, and this is balanced by the decrease due to radioactive decay, resulting in a constant supply of C in the Earth's atmospheric environment. 14 The amount of C is constant. Therefore, the amount of biomass resource-derived substances currently circulating in the environment 14 As mentioned above, the carbon concentration is approximately 1 × 10¹⁶ of the total carbon atoms. -12 The values ​​are approximately in the range of mol%. Therefore, the difference between these values ​​can be used to calculate the biomass ratio of a particular compound.

[0033] this 14 C is typically measured as follows: Using accelerator mass spectrometry based on a tandem accelerator, 13 C concentration ( 13 C / 12 C), 14 C concentration ( 14 C / 12 Perform measurement C). In the measurement, 14 As a modern standard reference for the concentration of C, the amount of cyclic carbon in nature as of 1950 14The C concentration will be used. The specific standard material will be the oxalic acid standard provided by NIST (National Institute of Standards and Technology). The specific radioactivity of carbon in this oxalic acid (per gram of carbon) will be used. 14 The radioactivity intensity of C is separated by carbon isotope, 13 The standard value is obtained by correcting C to a constant value and applying decay correction from 1950 AD to the measurement date. 14 This value is used as the C concentration value (100%). The ratio of this value to the value of the sample actually measured is the pMC value.

[0034] Therefore, if rubber is made from 100% biomass-derived materials, although there are regional differences, under normal conditions it will often not reach 100, and will show a value of approximately 110 pMC. On the other hand, regarding chemical substances derived from fossil fuels such as petroleum, 14 When the C concentration is measured, it will show a value of approximately 0 pMC (for example, 0.3 pMC). This value corresponds to a biomass ratio of 0% as mentioned above.

[0035] For the reasons stated above, using materials such as rubber with a high pMC value, that is, materials such as rubber with a high biomass ratio, in rubber compositions is preferable from an environmental protection standpoint.

[0036] Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, denatured NR, and denatured IR. For NR, common types used in the rubber industry can be used, such as SIR20, RSS#3, and TSR20. For IR, there are no particular limitations; common types used in the rubber industry can be used, such as IR2200. Examples of modified NR include deproteinized natural rubber (DPNR) and high-purity natural rubber. Examples of denatured NR include hydrogenated natural rubber (HNR) and grafted natural rubber. Examples of denatured IR include hydrogenated isoprene rubber and grafted isoprene rubber. These may be used individually or in combination of two or more types.

[0037] The butadiene rubber (BR) described above is not particularly limited, and for example, high-cis BR with a high cis content, BR containing syndiotactic polybutadiene crystals, and BR synthesized using a rare-earth catalyst (rare-earth BR) can be used. These may be used individually or in combination of two or more. In particular, it is preferable that the BR contains high-cis BR with a cis content of 90% by mass or more. The cis content is more preferably 95% by mass or more. The cis content can be measured by infrared absorption spectroscopy.

[0038] In this specification, the cis amount of BR refers to the cis amount of a single type of BR, and the average cis amount when there are multiple types of BR. The average cis content of BR can be calculated using the formula {Σ(content of each BR × cis content of each BR)} / total BR content. For example, if 20% of BR has a cis content of 90% and 10% has a cis content of 40% out of 100% of rubber components, the average cis content of BR is 73.3% (=(20 × 90 + 10 × 40) / (20 + 10)).

[0039] Both unmodified and modified BR can be used. Modified BR includes BR in which functional groups similar to those of modified rubber have been introduced. Hydrogenated butadiene polymers (hydrogenated BR) can also be used.

[0040] For example, products from companies such as Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Corporation can be used as BRs.

[0041] The styrene-butadiene rubber (SBR) mentioned above is not particularly limited, and for example, emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), etc., can be used. These may be used individually or in combination of two or more types.

[0042] The total styrene content of SBR is preferably 5% by mass or more, more preferably 20% by mass or more, and even more preferably 24% by mass or more. The total styrene content is preferably 60% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less. When the content is within the above range, a better effect tends to be obtained. In this specification, the total styrene content of SBR is defined as follows: 1 It can be measured by 1H-NMR.

[0043] The total styrene content of SBR refers to the styrene content of a single type of SBR if it is one type, and to the average styrene content if it is one of multiple types. The average styrene content of SBR can be calculated using the formula {Σ(content of each SBR × styrene content of each SBR)} / total content of all SBR. For example, if 85% of the rubber component is SBR with 40% styrene content and 5% is SBR with 25% styrene content, the average styrene content of the SBR is 39.2% (=(85 × 40 + 5 × 25) / (85 + 5)).

[0044] The total vinyl content of SBR is preferably 3% by mass or more, more preferably 10% by mass or more, and even more preferably 17% by mass or more. The total vinyl content is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. When the content is within the above range, the effect tends to be better. In this specification, the total vinyl content of SBRs can be measured by infrared absorption spectroscopy, where the vinyl content (1,2-bonded butadiene unit content) of each SBR is determined.

[0045] The total vinyl content (1,2-bonded butadiene unit content) of SBR is the ratio of vinyl bonds when the total mass of the butadiene portion in SBR is set to 100 (unit: mass%), where vinyl content [mass%] + cis content [mass%] + trans content [mass%] = 100 [mass%]. If there is only one type of SBR, it represents the vinyl content of that SBR; if there are multiple types, it represents the average vinyl content. The average vinyl content of SBR can be calculated using the formula: Σ{Content of each SBR × (100 [mass%] - Styrene content of each SBR [mass%]) × Vinyl content of each SBR [mass%]} / Σ{Content of each SBR × (100 [mass%] - Styrene content of each SBR [mass%])}. For example, if 100 parts by mass of rubber component, 75 parts by mass of SBR contain 40% by mass of styrene and 30% by mass of vinyl, and 25% by mass of vinyl, If 15 parts by mass of SBR have a 20% vinyl content and the remaining 10 parts by mass are other than SBR, the average vinyl content of the SBR is 28% by mass (= {75 × (100 [mass%] - 40 [mass%]) × 30 [mass%] + 15 × (100 [mass%] - 25 [mass%]) × 20 [mass%])} / {75 × (100 [mass%] - 40 [mass%]) + 15 × (100 [mass%] - 25 [mass%])}.

[0046] Both unmodified and modified SBR can be used. Modified SBR includes SBR with functional groups similar to those introduced in modified rubber. Hydrogenated styrene-butadiene copolymer (hydrogenated SBR) can also be used as SBR.

[0047] For example, SBR manufactured and sold by companies such as Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Co., Ltd. can be used. Alternatively, SBR synthesized by known methods can also be used.

[0048] When the above rubber composition contains an isoprene-based rubber that has not been epoxidized, the content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and also preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. When the content is within the above range, the effect tends to be better obtained.

[0049] When the above rubber composition contains unepoxidized BR, the content of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and also preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. When the content is within the above range, the effect tends to be better obtained.

[0050] When the above rubber composition contains unepoxidized SBR, the content of SBR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and also preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. When the content is within the above range, the effect tends to be better obtained.

[0051] The above rubber composition contains a pyridine compound represented by the following general formula (1). The pyridine compound is not particularly limited as long as it is represented by the following general formula (1) and exhibits the above-mentioned effects, and various types can be used.

[0052] [ka]

[0053] In formula (1) above, R bonded to the pyridine ring 1 ~R 5 R represents a hydrogen atom or a monovalent organic group, either identical or different. 1 ~R 5 They may be bonded to each other, or they may form a ring structure.

[0054] In the above equation (1), R 1 ~R 5If it is a monovalent organic group, the monovalent organic group may be an aryl group, heterocyclic group, alkyl group (preferably having 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms), alkenyl group (preferably having 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms), alkynyl group (preferably having 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms), alkoxy group (preferably having 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms), aryloxy group, arylalkoxy group, silyl group, hydroxyl group, amino group, halogen atom, carboxyl group, thiol group, epoxy group, acyl group, oligoaryl group, monovalent oligoheterocyclic group, alkylthio group, arylthio group, arylalkyl group, aryl Examples include alkoxy groups, arylalkylthio groups, azo groups, staniyl groups, phosphino groups, silyloxy groups, aryloxycarbonyl groups, alkoxycarbonyl groups, carbamoyl groups, arylcarbonyl groups, alkylcarbonyl groups, arylsulfonyl groups, alkylsulfonyl groups, arylsulfinyl groups, alkylsulfinyl groups, formyl groups, cyano groups, nitro groups, arylsulfonyloxy groups, alkylsulfonyloxy groups, alkylsulfonate groups, arylsulfonate groups, arylalkylsulfonate groups, boryl groups, sulfonium methyl groups, phosphonium methyl groups, phosphonate methyl groups, arylsulfonate groups, aldehyde groups, acetonitrile groups, etc. 1 ~R 5 If the monovalent organic group has substituents, it may have one substituent or two or more substituents.

[0055] The above R 1 ~R 5When a monovalent organic group has substituents, the substituents include halogen atoms such as fluorine, chlorine, bromine, and iodine; haloalkyl groups such as methyl chloride, methyl bromide, methyl iodide, fluoromethyl, difluoromethyl, and trifluoromethyl; linear or branched alkyl groups having 1 to 20 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, and tert-butyl; cyclic alkyl groups having 5 to 7 carbon atoms such as cyclopentyl, cyclohexyl, and cycloheptyl; methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, tert-butoxy, and pentyl groups. Examples include linear or branched alkoxy groups having 1 to 20 carbon atoms, such as xy group, hexyloxy group, heptyloxy group, and octyloxy group; hydroxyl group; thiol group; nitro group; cyano group; amino group; azo group; acyl group; alkenyl groups having 2 to 20 carbon atoms, such as vinyl group, 1-propenyl group, allyl group, butenyl group, and styryl group; alkynyl groups having 2 to 20 carbon atoms, such as ethynyl group, 1-propynyl group, propargyl group, and phenylacetylyl group; alkenyloxy groups such as vinyloxy group and allyloxy group; alkynyloxy groups such as ethynyloxy group and phenylacetyloxy group; and aryloxy groups such as phenoxy group, naphthoxy group, biphenyloxy group, and pyrenyloxy group. These groups may also be bonded to each other at any point to form a ring.

[0056] Among the monovalent organic groups mentioned above, electron-donating groups such as aryl groups, heterocyclic groups, alkyl groups, alkoxy groups, aryloxy groups, hydroxyl groups, silyl groups, boryl groups, amino groups, thiol groups, alkylthio groups, and arylthio groups, which may have substituents, are preferred from the viewpoint of the strength of the basicity of the pyridine compound represented by the general formula (1) above, with amino groups being particularly preferred. When the pyridine compound is strongly basic, it can form stronger ionic bonds and / or hydrogen bonds with the epoxidized diene rubber and carboxylic acid compound used in combination, and the effect tends to be better obtained. Here, an electron-donating group is, in organic electron theory, an atomic group that donates electrons to a substituted atomic group through inductive or resonance effects, and is one example of a group whose substituent constant (σp (para)) in Hammett's rule takes a negative value. The substituent constant (σp (para)) in Hammett's rule can be quoted from the Chemical Handbook Basic Edition, 5th Revised Edition (II-380; edited by the Chemical Society of Japan, Maruzen Co., Ltd.).

[0057] In other words, the pyridine compound represented by the above general formula (1) has R bonded to the pyridine ring in general formula (1). 1 ~R 5 at least one of (preferably R) 1 ~R 5 It is preferable that one or two of these groups are electron-donating groups, and particularly preferable that they are amino groups.

[0058] Examples of the above-mentioned amino groups include primary amino groups, secondary amino groups, and tertiary amino groups. Note that a primary amino group refers to a monovalent substituent represented by -NH2. A secondary amino group is represented by -NHR 11 (R 11 represents a hydrocarbon group which may have substituents. ) represents a monovalent substituent. A tertiary amino group is represented as -NR 12 R 13 (R 12 and R 13 ) represents a hydrocarbon group that may have substituents, either identical or different. ) refers to a monovalent substituent.

[0059] The R bonded to the pyridine ring in the general formula (1) above 1 ~R 5 While the mechanism by which the effect is enhanced when at least one of the groups is an amino group is not clear, it is presumed that the presence of an amino group increases the basicity of the pyridine compound, allowing it to react more readily with the epoxy moiety and significantly improving its heat resistance.

[0060] Specific examples of pyridine compounds represented by the above general formula (1) include pyridine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 3-isobutylpyridine, 2-n-hexylpyridine, 3-n-hexylpyridine, 3,5-dimethylpyridine, 2-benzylpyridine, 3-phenylpyridine, 2,6-diphenylpyridine, 2-(3-phenylpropyl)pyridine, 2-methoxypyridine, 3,5-dimethoxypyridine, 2-aminopyridine, 3-aminopyridine, 4-aminopyridine, 4-(methylamino)pyridine, 2,3-diaminopyridine, 2,6-diaminopyridine, and 3,4-di Suitable examples include aminopyridine, 4-dimethylaminopyridine, 2-amino-3-methylpyridine, 2-amino-4-methylpyridine, 2-amino-4-ethylpyridine, 2-benzylaminopyridine, 5-amino-2-methoxypyridine, 2-amino-5-methoxypyridine, 2-amino-3-methoxypyridine, 2-amino-4-methoxypyridine, 2-amino-6-methoxypyridine, 2-amino-3-ethoxypyridine, pyridine-2-thiol, pyridine-2,4-diol, 4-pyrrolidinopyridine, 2-hydroxypyridine, 3-hydroxypyridine, and 3,4-dihydroxypyridine. These may be used individually or in combination of two or more. Among these, 4-dimethylaminopyridine and 2,6-diaminopyridine are preferred, and 2,6-diaminopyridine is more preferred, from the viewpoint of the strength of the basicity of the pyridine compounds represented by the above general formula (1).

[0061] As the pyridine compound represented by the above general formula (1), for example, products from Tokyo Chemical Industry Co., Ltd. and others can be used.

[0062] In the above rubber composition, the content of the pyridine compound represented by the above general formula (1) is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, even more preferably 0.5 parts by mass or more, and even more preferably 1.0 part by mass or more, per 100 parts by mass of the rubber component, and also preferably 10.0 parts by mass or less, more preferably 7.0 parts by mass or less, even more preferably 5.0 parts by mass or less, and even more preferably 3.0 parts by mass or less. When the content is within the above range, a better effect tends to be obtained. The effect is actually confirmed when the content is 10 parts by mass or less. On the other hand, from the viewpoint of crosslinking density, per 100 parts by mass of the rubber component, 1.0 part by mass or less is preferred, 0.5 parts by mass or less is more preferred, 0.05 parts by mass or more is preferred, and 0.1 parts by mass or more is even more preferred.

[0063] The above rubber composition contains a divalent or greater carboxylic acid compound. In this specification, a divalent or greater carboxylic acid compound means a compound having two or more carboxyl groups.

[0064] The above-mentioned divalent or higher carboxylic acid compound is not particularly limited as long as it exhibits the above-mentioned effects, and may be, for example, any of divalent or higher aliphatic carboxylic acid compounds, alicyclic carboxylic acid compounds, or aromatic carboxylic acid compounds. Furthermore, the divalent or higher carboxylic acid compound may have substituents. Examples of such substituents include hydroxyl groups, alkoxy groups, amino groups, etc. The number of substituents may be one or two or more. Furthermore, the types of substituents may be one or two or more.

[0065] Examples of the divalent or higher carboxylic acid compounds mentioned above include divalent carboxylic acid compounds such as maleic acid, fumaric acid, phthalic acid, malic acid, tartaric acid, and suberic acid; trivalent carboxylic acid compounds such as citric acid; tetravalent carboxylic acid compounds such as pyromellitic acid; and hexavalent carboxylic acid compounds such as mellitic acid. These divalent or higher carboxylic acid compounds may be used individually or in combination of two or more.

[0066] Among the above-mentioned divalent or greater carboxylic acid compounds, divalent carboxylic acid compounds are preferred from the viewpoint of obtaining better effects. A compound represented by the following formula (I) can be suitably used as the divalent carboxylic acid compound. Because this compound has carboxyl groups at both ends, it is possible to form a strong network between polymers. HOOC-A-COOH (I) (In formula (I), A is a divalent hydrocarbon group having 1 to 10 carbon atoms, and may have substituents.)

[0067] In formula (I) above, the hydrocarbon group A may be aliphatic, alicyclic, or aromatic, and the aliphatic and alicyclic hydrocarbon groups may be saturated or unsaturated. Furthermore, the hydrogen atoms of the alicyclic and aromatic hydrocarbon groups may be substituted with alkyl groups. In addition, the aliphatic hydrocarbon group may be linear or branched.

[0068] From the viewpoint of obtaining a better effect, the number of carbon atoms in the hydrocarbon group A in formula (I) above is preferably 2 or more, more preferably 5 or more, even more preferably 7 or more, and even more preferably 10 or more. Furthermore, the number of carbon atoms is preferably 20 or less, more preferably 17 or less, even more preferably 15 or less, and even more preferably 12 or less. On the other hand, from the viewpoint of improving the crosslinking rate, it is preferably 10 or less, more preferably 7 or less, even more preferably 5 or less, and preferably 1 or more.

[0069] Specific examples of hydrocarbon groups in A of formula (I) above include alkylene groups, alkenylene groups, cycloalkylene groups, and arylene groups, but alkylene groups are preferred. Examples of such alkylene groups include linear alkylene groups such as ethylene groups, n-propylene groups, n-butylene groups, n-hexylene groups, and n-dodecylen groups, and branched alkylene groups such as isopropylene groups, isobutylene groups, and 2-methylpropylene groups. From the viewpoint of obtaining a better effect, linear alkylene groups are preferred, ethylene groups, n-propylene groups, n-hexylene groups, and n-dodecylen groups are more preferred, and n-dodecylen groups are even more preferred.

[0070] The hydrocarbon group A in formula (I) above may have substituents. Examples of substituents include hydroxyl groups, alkoxy groups, amino groups, etc. The number of substituents may be one or two or more. Furthermore, the types of substituents may be one or two or more.

[0071] In the above rubber composition, the content of the divalent or greater carboxylic acid compound is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, even more preferably 0.5 parts by mass or more, even more preferably 1.0 part by mass or more, even more preferably 2.0 parts by mass or more, per 100 parts by mass of the rubber component, and also preferably 10.0 parts by mass or less, more preferably 7.0 parts by mass or less, even more preferably 5.0 parts by mass or less, and even more preferably 3.0 parts by mass or less. When the content is within the above range, a better effect tends to be obtained. The effect is actually confirmed when the content is 10 parts by mass or less. On the other hand, from the viewpoint of crosslinking density, per 100 parts by mass of the rubber component, 2.0 parts by mass or less is preferred, 1.0 part by mass or less is more preferred, 0.5 parts by mass or less is even preferred, and 0.05 parts by mass or more is preferred, and 0.1 parts by mass or more is even preferred.

[0072] The above rubber composition preferably contains a filler. The above-mentioned fillers are not particularly limited, and materials known in the rubber field can be used. Examples include inorganic fillers such as carbon black, silica, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, and mica, as well as biochar (BIO CHAR); and poorly dispersible fillers. Among these, carbon black and silica are preferred from the viewpoint of obtaining better effects, and the inclusion of carbon black is particularly preferred.

[0073] While the mechanism by which carbon black is more effective when included as a filler is not clear, it is presumed that the inclusion of carbon black improves the thermal conductivity of the rubber, allowing for effective dissipation of heat generated within the rubber. This suppresses the generation of localized high temperatures, slows down the progression of thermal decomposition, and significantly improves heat resistance.

[0074] The carbon black used is not particularly limited and includes N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. The raw materials for carbon black may be biomass materials such as lignin and vegetable oil, or pyrolysis oil obtained by thermal decomposition of waste tires. The manufacturing method for carbon black may be combustion such as the furnace method, hydrothermal carbonization (HTC), or thermal decomposition of methane such as the thermal black method. Commercially available products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., and Columbia Carbon Corporation. Carbon black may be used alone or in combination of two or more types.

[0075] The specific surface area (N2SA) of carbon black for nitrogen adsorption is 5m². 2 Preferably 20m / g or more. 2 More preferably 40m 2 More preferably 75m / g or more. 2 More than / g is even more preferable. Also, the above N2SA is 200m2 Preferably less than / g, 130m 2 / g or less is more preferable, 120m 2 A value of less than / g is even more preferable. Within the above range, the effect tends to be better. On the other hand, from the viewpoint of processability, 75m 2 Preferably less than / g, 60m 2 More preferably less than / g, 40m 2 It is even more preferable that the amount be less than / g, and also 3m 2 Preferably 10m / g or more, 2 A value of / g or higher is more preferable. The specific surface area for nitrogen adsorption of carbon black is determined according to JIS K6217-2:2001.

[0076] In the above rubber composition, the silica that can be used is not particularly limited, and common silica used in the tire industry can be used, such as silica prepared by a dry process (anhydrous silica) or silica prepared by a wet process (hydrated silica). The raw material for silica is not particularly limited, and may be a mineral-derived raw material such as quartz, or a biological-derived raw material such as rice husks (for example, silica made from biomass materials such as rice husks), or silica recycled from silica-containing products may be used. Among these, hydrated silica prepared by a wet process is preferred because it has a high silanol group content. These silicas may be used individually or in combination of two or more types.

[0077] Silica derived from biomass materials can be obtained, for example, by extracting silicates from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and then using these silicates to react with sulfuric acid in the same way as conventional wet silica, the precipitate of silicon dioxide is filtered, washed with water, dried, and pulverized.

[0078] The silica recycled from silica-containing products can be, for example, silica recovered from products containing silica such as semiconductors and other electronic components, tires, desiccants, and diatomaceous earth and other filter materials. The recovery method is not particularly limited and can include thermal decomposition and decomposition by electromagnetic waves. Among these, silica recovered from semiconductors and other electronic components or tires is preferred.

[0079] When silica crystallizes, it becomes insoluble in water, and its component, silicic acid, cannot be utilized. By controlling the combustion temperature and combustion time, the crystallization of silica in rice husk ash can be suppressed (see Japanese Patent Publication No. 2009-2594, Akita Prefectural University Web Journal B / 2019, vol.6, pp.216-222, etc.).

[0080] Amorphous silica extracted from rice husks can be commercially available from companies such as Wilmar.

[0081] The nitrogen adsorption specific surface area (N2SA) of silica is preferably 50 m². 2 / g or more, more preferably 80m 2 / g or more, more preferably 100m 2 It is 1 / g or more. Furthermore, the upper limit of N2SA in silica is not particularly limited, but preferably 350m 2 Less than / g, more preferably 300m 2 / g or less, more preferably 250m 2 It is less than / g. Within the above range, better effects tend to be obtained. Note that the N2SA value of silica is measured by the BET method in accordance with ASTM D3037-93.

[0082] Examples of poorly dispersible fillers include microfibrillated plant fibers, short fibrous cellulose, and gel-like compounds. Among these, microfibrillated plant fibers are preferred.

[0083] As the above-mentioned microfibrillated plant fiber, cellulose microfibrils are preferred in that they provide good reinforcing properties. The cellulose microfibrils are not particularly limited as long as they are derived from natural products, and examples include resource biomass such as fruits, grains, and root vegetables; wood, bamboo, hemp, jute, and kenaf, as well as waste biomass such as pulp, paper, cloth, agricultural residues, food waste, and sewage sludge obtained from these raw materials, unused biomass such as rice straw, wheat straw, and thinned wood, and cellulose produced by sea squirts, acetic acid bacteria, etc. One type of these microfibrillated plant fiber may be used, or two or more types may be used in combination.

[0084] In this specification, cellulose microfibrils typically refer to cellulose fibers having an average fiber diameter of 10 μm or less, and more typically, cellulose fibers having a microstructure with an average fiber diameter of 500 nm or less, formed by an aggregate of cellulose molecules. Typical cellulose microfibrils are formed, for example, as aggregates of cellulose fibers having the average fiber diameter described above.

[0085] In the above rubber composition, the filler content (total amount of fillers such as carbon black and silica) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 25 parts by mass or more, even more preferably 40 parts by mass or more, even more preferably 50 parts by mass or more, per 100 parts by mass of the rubber component, and also preferably 200 parts by mass or less, more preferably 150 parts by mass or less, even more preferably 120 parts by mass or less, even more preferably 100 parts by mass or less, and even more preferably 80 parts by mass or less. When the content is within the above range, the effect tends to be better obtained. On the other hand, from the viewpoint of processability, per 100 parts by mass of the rubber component, 50 parts by mass or less is preferred, 40 parts by mass or less is more preferred, 25 parts by mass or less is even more preferred, 10 parts by mass or less is even more preferred, 5 parts by mass or less is even more preferred, and 1 part by mass or more is preferred, and 3 parts by mass or more is even more preferred.

[0086] In the above rubber composition, when the filler content is 50 parts by mass or more per 100 parts by mass of rubber component, although the mechanism by which a greater effect is obtained is not clear, it is presumed that by incorporating a predetermined amount or more of filler, the thermal conductivity of the rubber is improved, and the heat generated inside the rubber can be effectively diffused. This suppresses the generation of localized high temperatures, slows down the progress of thermal decomposition, and significantly improves heat resistance.

[0087] When the above rubber composition contains carbon black, the carbon black content is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 25 parts by mass or more, even more preferably 40 parts by mass or more, even more preferably 50 parts by mass or more, per 100 parts by mass of the rubber component, and also preferably 200 parts by mass or less, more preferably 150 parts by mass or less, even more preferably 120 parts by mass or less, even more preferably 100 parts by mass or less, and even more preferably 80 parts by mass or less. When the content is within the above range, the effect tends to be better obtained. On the other hand, from the viewpoint of processability, per 100 parts by mass of the rubber component, 50 parts by mass or less is preferred, 40 parts by mass or less is more preferred, 25 parts by mass or less is even more preferred, 10 parts by mass or less is even more preferred, 5 parts by mass or less is even more preferred, and 1 part by mass or more is preferred, and 3 parts by mass or more is even more preferred.

[0088] When the above rubber composition contains silica, the silica content is preferably 5 parts by mass or more, more preferably 25 parts by mass or more, even more preferably 30 parts by mass or more, and also preferably 150 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 70 parts by mass or less, per 100 parts by mass of the rubber component. When the silica content is within the above range, the effect tends to be better obtained.

[0089] If the above rubber composition contains silica, it is preferable that it further contains a silane coupling agent. The silane coupling agent is not particularly limited and any known in the rubber field can be used, for example, bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl) trisulfide, bis(4-trimethoxysilylbutyl) trisulfide, bis(3-triethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl) disulfide, bis(4-triethoxysilylbutyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(2-trimethoxysilylethyl) disulfide, bis(4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N, Examples include sulfide-based compounds such as N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based compounds such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and Momentive's NXT and NXT-Z; vinyl-based compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based compounds such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Commercially available products from companies such as Evonik, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., and Toray Dow Corning Co., Ltd. can be used. These can be used individually or in combination of two or more types.

[0090] In the above rubber composition, the content of the silane coupling agent is preferably 0.1 parts by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more, per 100 parts by mass of silica. The upper limit of the content is preferably 50 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0091] The above rubber composition may contain a plasticizer. In this specification, "plasticizer" refers to a material that imparts plasticity to rubber components, and is a concept that includes both liquid plasticizers at 1 atmosphere and room temperature (25°C) and solid plasticizers at 1 atmosphere and room temperature (25°C). Examples of plasticizers include resin components, oils, liquid polymers, and ester-based plasticizers. These plasticizers may be derived from mineral resources such as petroleum and natural gas, from biomass, or from naphtha recycled from rubber or non-rubber products. In addition, low molecular weight hydrocarbon components obtained by thermal decomposition and extraction of used tires or products containing various components may be used as plasticizers. These plasticizers may be used individually or in combination of two or more.

[0092] Examples of the plasticizers mentioned above include oils, liquid polymers, and resins. These may be used individually or in combination of two or more.

[0093] Examples of oils include mineral oil, vegetable oil, and animal oil. From a life cycle assessment perspective, waste oil used in rubber mixers and engines, or refined waste cooking oil used in restaurants, may also be used. In this specification, mineral oil refers to oil derived from mineral resources such as petroleum and natural gas. Examples of mineral oil include paraffinic oils (mineral oil), naphthenic oils, and aromatic oils. Specific examples of mineral oil include MES (Mild Extract Solvated), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), and RAE (Residual Aromatic Extract). Furthermore, for environmental reasons, oils with a low content of polycyclic aromatic compounds (PCA) can be used. Examples of such low-PCA oils include MES, TDAE, and heavy naphthenic oils.

[0094] In this specification, vegetable oils include, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grapeseed oil, and wood wax. Furthermore, vegetable oils may also include refined oils (such as salad oil) obtained by refining the above oils, transesterified oils obtained by transesterifying the above oils, hydrogenated oils obtained by hydrogenating the above oils, thermally polymerized oils obtained by thermally polymerizing the above oils, oxidized polymerized oils obtained by oxidizing the above oils, and waste cooking oils recovered from use as edible oils. Note that vegetable oils may be liquid or solid at 1 atmosphere and room temperature (25°C). These vegetable oils may be used individually or in combination of two or more types.

[0095] The vegetable oil according to this embodiment preferably contains acylglycerol, and more preferably contains triacylglycerol. In this specification, acylglycerol refers to a compound in which a hydroxyl group of glycerin and a fatty acid are ester-bonded. The acylglycerol is not particularly limited and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Furthermore, the acylglycerol may be a monomer, a dimer, or a polymer of three or more. Note that acylglycerols of two or more can be obtained by thermal polymerization, oxidative polymerization, etc. Also, the acylglycerol may be a liquid or a solid at 1 atmosphere and room temperature (25°C).

[0096] The method for confirming whether the rubber composition contains the acylglycerol is not particularly limited, 1 This can be confirmed by 1H-NMR measurement. For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at 1 atmosphere and room temperature (25°C) for 24 hours, and after removing the rubber composition, it is measured at room temperature. 1 When 1H-NMR was measured and the tetramethylsilane (TMS) signal was set to 0.00 ppm, signals were observed around 5.26 ppm, 4.28 ppm, and 4.15 ppm. These signals are presumed to originate from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group. In this paragraph, "around" refers to a range of ±0.10 ppm.

[0097] The aforementioned fatty acids are not particularly limited and may be either unsaturated or saturated fatty acids. Examples of unsaturated fatty acids include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. Examples of saturated fatty acids include butyric acid and lauric acid.

[0098] In particular, it is desirable that the fatty acid contains fatty acids with few double bonds, i.e., saturated fatty acids or monounsaturated fatty acids, and oleic acid is preferred. As a vegetable oil containing such fatty acids, for example, a vegetable oil containing saturated fatty acids or monounsaturated fatty acids may be used, or a vegetable oil that has been modified by transesterification or other means may be used. Furthermore, in order to produce a vegetable oil containing such fatty acids, plants may be improved by breeding, genetic modification, genome editing, etc.

[0099] As for the oil, commercially available products from companies such as Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kosan Co., Ltd., and Nisshin Oillio Group Ltd. can be used.

[0100] Examples of the above-mentioned liquid polymers include liquid diene polymers (liquid rubber) and liquid farnesene polymers that are liquid at 1 atmosphere and 25°C. Examples of liquid rubbers include liquid styrene-butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), liquid styrene-isoprene copolymer (liquid SIR), liquid styrene-butadiene-styrene block copolymer (liquid SBS block polymer), and liquid styrene-isoprene-styrene block copolymer (liquid SIS block polymer). These polymers may have polar groups modified at the ends or main chain. Hydrogenated versions of these polymers can also be used.

[0101] The above liquid diene polymer has a weight-average molecular weight (Mw) on a polystyrene basis, measured by gel permeation chromatography (GPC), of 1.0 × 10⁻⁶. 3 ~5.0×10 4 Preferably, 3.0 × 10 3 ~1.5×10 4 It is more preferable that this is the case. Furthermore, the lower or upper limit of Mw for the liquid diene polymer may be 4500 or 8500. In this specification, the Mw of liquid diene polymers is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0102] Examples of liquid diene polymers that can be used include products from companies such as Sartomer and Kuraray.

[0103] The above-mentioned resin can be any resin commonly used in tire compounding, and may be either liquid or solid at 1 atmosphere and room temperature (25°C). Examples include aromatic vinyl polymers, coumarone indene resins, coumarone resins, indene resins, phenolic resins, rosin resins, petroleum resins, terpene resins, and acrylic resins. The resin may also be a hydrogenated resin. These may be used individually or in combination of two or more. The resin itself may also be a copolymer of monomer components of multiple origins. Among these, aromatic vinyl polymers, petroleum resins, terpene resins, and their hydrogenated resins are particularly desirable.

[0104] When using a resin that is solid at 1 atmosphere and room temperature, the softening point of the above-mentioned resin is preferably 50°C or higher, more preferably 55°C or higher, even more preferably 60°C or higher, and particularly preferably 85°C or higher. Furthermore, it is preferably 160°C or lower, more preferably 150°C or lower, even more preferably 140°C or lower, and particularly preferably 100°C or lower. When the softening point is within the above range, the effect tends to be better obtained. When the resin is liquid at 1 atmosphere and room temperature, the softening point is preferably 20°C or lower, preferably 10°C or lower, and preferably 0°C or lower. In the case of hydrogenated resins, it is desirable that the softening point be the same as described above. The softening point of the above resin is determined by measuring the softening point specified in JIS K6220-1:2001 using a ring-type softening point measuring device, and the temperature at which the sphere descends is the softening point.

[0105] The above-mentioned aromatic vinyl polymer is a polymer containing aromatic vinyl monomers as constituent units. Examples include resins obtained by polymerizing α-methylstyrene and / or styrene, specifically, homopolymers of styrene (styrene resin), homopolymers of α-methylstyrene (α-methylstyrene resin), copolymers of α-methylstyrene and styrene, copolymers of styrene and other monomers.

[0106] The above-mentioned coumarone-indene resin is a resin that contains coumarone and indene as the main monomer components that make up the resin's backbone (main chain). Other monomer components that can be included in the backbone besides coumarone and indene include styrene, α-methylstyrene, methylindene, and vinyltoluene.

[0107] The coumarone resin described above is a resin that contains coumarone as the main monomer component that constitutes the resin's backbone (main chain).

[0108] The above-mentioned indene resin is a resin that contains indene as the main monomer component that constitutes the resin's backbone (main chain).

[0109] As the phenolic resin mentioned above, known polymers such as those obtained by reacting phenol with aldehydes such as formaldehyde, acetaldehyde, and furfural using an acid or alkali catalyst can be used. Among these, those obtained by reaction with an acid catalyst (such as novolac-type phenolic resins) are preferred.

[0110] Examples of the rosin resins mentioned above include natural rosin, polymerized rosin, modified rosin, their ester compounds, and rosin-based resins represented by their hydrogenated products.

[0111] Examples of the above petroleum resins include C5 resins, C9 resins, C5 / C9 resins, dicyclopentadiene (DCPD) resins, C9 / DCPD resins, and hydrogenated versions thereof. Among these, DCPD resins, hydrogenated DCPD resins, C9 / DCPD resins, and C9 / hydrogenated DCPD resins are preferred.

[0112] The above-mentioned terpene resins are polymers containing terpenes as constituent units. Examples include polyterpene resins obtained by polymerizing terpene compounds, and aromatically modified terpene resins obtained by polymerizing terpene compounds and aromatic compounds. As aromatically modified terpene resins, terpene-phenol resins made from terpene compounds and phenolic compounds, terpene-styrene resins made from terpene compounds and styrene compounds, and terpene-phenol-styrene resins made from terpene compounds, phenolic compounds, and styrene compounds can also be used. Examples of terpene compounds include α-pinene and β-pinene, examples of phenolic compounds include phenol and bisphenol A, and examples of aromatic compounds include styrene compounds (styrene, α-methylstyrene, etc.). Among these, aromatically modified terpene resins are preferred.

[0113] The above-mentioned acrylic resin is a polymer containing acrylic monomers as constituent units. Examples include styrene-acrylic resins such as styrene-acrylic resin, which have carboxyl groups and are obtained by copolymerizing an aromatic vinyl monomer component with an acrylic monomer component. Among these, solvent-free carboxyl group-containing styrene-acrylic resins can be suitably used.

[0114] Examples of resins that can be used include those from Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, ExxonMobil, Kraton, Nippon Paint Chemical Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Corporation, Arakawa Chemical Industries, Ltd., Taoka Chemical Industries, Ltd., and others.

[0115] From a sustainability perspective, it is desirable to use plant-derived plasticizers such as the aforementioned plant-derived oils and farnesene polymers as plasticizers.

[0116] Farnesene polymers are polymers obtained by polymerizing farnesene and have constituent units based on farnesene. Farnesene has isomers such as α-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecatetraene) and β-farnesene (7,11-dimethyl-3-methylene-1,6,10-dodecatriene), but (E)-β-farnesene, which has the following structure, is preferred. [ka]

[0117] The farnesene polymer may be a farnesene homopolymer (farnesene homopolymer) or a farnesene-vinyl monomer copolymer (farnesene-vinyl monomer copolymer). These may be used individually or in combination of two or more. Among these, the farnesene-vinyl monomer copolymer is preferred.

[0118] Examples of vinyl monomers include aromatic vinyl compounds such as styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-tert-butylstyrene, 5-t-butyl-2-methylstyrene, vinylethylbenzene, divinylbenzene, trivinylbenzene, divinylnaphthalene, tert-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl)dimethylaminoethyl ether, N,N-dimethylaminoethylstyrene, N,N-dimethylaminomethylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-t-butylstyrene, 3-t-butylstyrene, 4-t-butylstyrene, vinylxylene, vinylnaphthalene, vinyltoluene, vinylpyridine, diphenylethylene, and tertiary amino group-containing diphenylethylene, as well as conjugated diene compounds such as butadiene and isoprene. These may be used individually or in combination of two or more. Among these, butadiene is preferred. In other words, a copolymer of farnesene and butadiene (farnesene-butadiene copolymer) is preferred as the farnesene-vinyl monomer copolymer.

[0119] In farnesene-vinyl monomer copolymers, the mass-based copolymerization ratio (farnesene / vinyl monomer) of farnesene to vinyl monomer is preferably 40 / 60 to 90 / 10.

[0120] Farnesene polymers with a weight-average molecular weight (Mw) of 3,000 to 300,000 are preferably used. The Mw of the farnesene polymer is preferably 8,000 or more, more preferably 10,000 or more, and also preferably 100,000 or less, more preferably 60,000 or less, and even more preferably 50,000 or less. Within the above range, the effect tends to be more favorably obtained.

[0121] The farnesene polymer may be in either a liquid or solid state at 1 atmosphere and room temperature (25°C). Of these, a liquid farnesene polymer at 1 atmosphere and room temperature (25°C) is preferred.

[0122] In the above rubber composition, the plasticizer content (total amount of plasticizer) is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 25 parts by mass or less. When the content is within the above range, the effect tends to be better obtained. Furthermore, the plasticizer content includes the amount of oil and resin contained in oil-extracted rubber and resin-extracted rubber.

[0123] In the above rubber composition, the content of solid plasticizer in a solid state at 1 atmosphere and room temperature (25°C) is preferably 20 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 1 part by mass or less, per 100 parts by mass of the rubber component, and may be 0 parts by mass. When the content is within the above range, a better effect tends to be obtained.

[0124] In the above rubber composition, the content of the resin in a solid state at 1 atmosphere and room temperature (25°C) is preferably 20 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 1 part by mass or less, per 100 parts by mass of the rubber component, and may be 0 parts by mass. When the content is within the above range, a better effect tends to be obtained.

[0125] In the above rubber composition, the content of liquid plasticizer in a liquid state at 1 atmosphere and room temperature (25°C) is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 25 parts by mass or less. When the content is within the above range, the effect tends to be better obtained. Furthermore, the liquid plasticizer content includes the amount of oil contained in the oil-stretched rubber and the amount of liquid resin in the resin-stretched rubber that has been stretched with liquid resin.

[0126] In the above rubber composition, the oil content is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 25 parts by mass or less. When the content is within the above range, the effect tends to be better obtained. Note that the oil content also includes the amount of oil contained in the oil-applied rubber.

[0127] The above rubber composition may further contain vulcanized rubber particles. Vulcanized rubber particles are particles made of vulcanized rubber, and specifically, rubber powder as specified in JIS K 6316:2017 can be used. From the viewpoint of environmental considerations and cost, recycled rubber powder produced from crushed waste tires is preferred. These may be used individually or in combination of two or more types.

[0128] The vulcanized rubber particles are not particularly limited and may be either unmodified or modified vulcanized rubber particles.

[0129] Commercially available vulcanized rubber particles can be used, for example, products from Lehigh, Muraoka Rubber Industries, Ltd., and others.

[0130] In the above rubber composition, the content of vulcanized rubber particles is preferably 5 parts by mass or more, more preferably 7 parts by mass or more, even more preferably 10 parts by mass or more, and preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less, per 100 parts by mass of the rubber component. When the content is within the above range, a better effect tends to be obtained.

[0131] The above rubber composition preferably contains an anti-aging agent from the viewpoint of crack resistance, ozone resistance, etc.

[0132] While not particularly limited, examples of anti-aging agents include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), and N,N'-ditril-p-phenylenediamine. Examples include p-phenylenediamine-based antioxidants such as methyl amine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol-based antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred, with polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline being more preferred. Commercially available products include those from companies such as Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., and Flexis.

[0133] In the above rubber composition, the content of the anti-aging agent is preferably 0.2 parts by mass or more, more preferably 2.0 parts by mass or more, and even more preferably 3.4 parts by mass or more, per 100 parts by mass of the rubber component. The content is preferably 10.0 parts by mass or less, and more preferably 6.0 parts by mass or less.

[0134] The above rubber composition may also contain stearic acid. When the above rubber composition contains stearic acid, the stearic acid content is preferably 0.5 parts by mass or more, more preferably 1.5 parts by mass or more, even more preferably 2.0 parts by mass or more, and preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, per 100 parts by mass of the rubber component.

[0135] In addition, conventionally known stearic acid can be used, such as products from NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Corporation, Chiba Fatty Acid Co., Ltd.

[0136] The above rubber composition preferably contains zinc oxide. When the above rubber composition contains zinc oxide, the zinc oxide content is preferably 0.5 parts by mass or more, more preferably 1.5 parts by mass or more, even more preferably 2.0 parts by mass or more, even more preferably 4.0 parts by mass or more, even more preferably 5.0 parts by mass or more, per 100 parts by mass of the rubber component, and also preferably 10.0 parts by mass or less, more preferably 8.0 parts by mass or less, and even more preferably 6.0 parts by mass or less. Within the above range, the effect tends to be better obtained. On the other hand, from the viewpoint of vulcanization rate, per 100 parts by mass of the rubber component, 5.0 parts by mass or less is preferred, 4.0 parts by mass or less is more preferred, 2.0 parts by mass or less is even preferred, 0.1 parts by mass or more is preferred, 0.5 parts by mass or more is more preferred, and 1.0 part by mass or more is even preferred.

[0137] In addition, conventionally known zinc oxides can be used, such as products from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., and Sakai Chemical Industry Co., Ltd.

[0138] While the mechanism by which the above rubber composition becomes more effective when it contains zinc oxide is not clear, it is presumed that the inclusion of zinc oxide allows it to form reversible ionic and hydrogen bonds, thereby reinforcing the ionic and hydrogen bonds between the pyridine compound and the divalent or higher carboxylic acid compound, and thus significantly improving heat resistance.

[0139] The above rubber composition may contain wax. When the above rubber composition contains wax, the wax content is preferably 0.5 parts by mass or more, more preferably 1.6 parts by mass or more, and preferably 8.0 parts by mass or less, and more preferably 5.0 parts by mass or less, per 100 parts by mass of the rubber component.

[0140] The wax is not particularly limited, and any wax commonly used in the tire industry can be suitably used. Examples include mineral waxes and plant-derived waxes. Mineral waxes refer to waxes derived from mineral resources such as oil and natural gas. Plant-derived waxes refer to waxes derived from natural resources such as plants. Among these, mineral waxes are preferred. Examples of plant-derived waxes include rice wax, carnauba wax, and candelilla wax. Examples of mineral waxes include paraffin wax, microcrystalline wax, and selected special waxes thereof, with paraffin wax being preferred. The wax according to this embodiment does not contain stearic acid. The wax can be commercially available from companies such as Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Paramelt Co., Ltd. These waxes may be used individually or in combination of two or more types.

[0141] The above rubber composition may also contain sulfur as a crosslinking agent, in that it forms appropriate crosslinked chains in the polymer chains and imparts good performance.

[0142] In the above rubber composition, the sulfur content is preferably 7.0 parts by mass or less, more preferably 5.0 parts by mass or less, even more preferably 4.0 parts by mass or less, even more preferably 2.0 parts by mass or less, even more preferably 1.0 part by mass or less, and even more preferably 0.5 parts by mass or less, per 100 parts by mass of the rubber component, and may be 0 parts by mass or less. When the content is within the above range, the effect tends to be better obtained.

[0143] Examples of sulfur commonly used in the rubber industry include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur. Commercially available products include those from Tsurumi Chemical Industries, Karuizawa Sulfur Co., Ltd., Shikoku Chemicals Co., Ltd., Flexis Co., Ltd., Nippon Dry Distillation Co., Ltd., and Hosoi Chemical Industry Co., Ltd. These can be used individually or in combination of two or more types.

[0144] The above rubber composition may contain a vulcanization accelerator. In the above rubber composition, there are no particular restrictions on the content of the vulcanization accelerator, and it can be freely determined according to the desired vulcanization rate and crosslinking density. However, it is preferably 8.0 parts by mass or less, more preferably 6.0 parts by mass or less, even more preferably 5.0 parts by mass or less, even more preferably 4.0 parts by mass or less, even more preferably 2.0 parts by mass or less, and even more preferably 1.0 part by mass or less per 100 parts by mass of rubber component, and it may also be 0 parts by mass.

[0145] There are no particular restrictions on the type of vulcanization accelerator; commonly used ones can be used. Examples of vulcanization accelerators include benzothiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiadylsulfenamide; thiram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazolesulfenamide, Nt-butyl-2-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, and N,N'-diisopropyl-2-benzothiazolesulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, diortotrilguanidine, and orthotrilbiguanidine. These may be used individually or in combination of two or more. Among them, sulfenamide, guanidine, and benzothiazole vulcanization accelerators are preferred.

[0146] In addition to the above components, the above rubber composition may also contain other compounding agents commonly used in the tire industry, such as mold release agents.

[0147] In this specification, various materials containing carbon atoms (e.g., rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from atmospheric carbon dioxide. As a method for obtaining the formulations of the present invention from carbon dioxide, carbon dioxide may be directly converted, or methane obtained through a methanation process in which methane is synthesized from carbon dioxide may be converted.

[0148] The above rubber composition is obtained by kneading each of the above components using a rubber kneading device such as an open roll or Banbury mixer, and then crosslinking the rubber composition.

[0149] Regarding the mixing conditions, in the base mixing step where additives other than the crosslinking agent (vulcanizing agent) and vulcanization accelerator are mixed, the mixing temperature is preferably 100°C or higher, more preferably 120°C or higher, and also preferably 180°C or lower, more preferably 170°C or lower. In the finish mixing step where the vulcanizing agent and vulcanization accelerator are mixed, the mixing temperature is preferably 80°C or higher, also preferably 120°C or lower, more preferably 110°C or lower. Furthermore, the mixed composition is usually subjected to a crosslinking (vulcanization) treatment such as press crosslinking (vulcanization). The crosslinking (vulcanization) temperature is preferably 140°C or higher, more preferably 150°C or higher, also preferably 190°C or lower, more preferably 185°C or lower.

[0150] The above rubber composition (the rubber composition after crosslinking) preferably has an elongation EB at break of 1000% or less before the heat aging test. More preferably it is 800% or less, and even more preferably 700% or less. The lower limit is preferably 300% or more, more preferably 400% or more, and even more preferably 500% or more. When it is within the above range, the effect tends to be better obtained.

[0151] The above rubber composition (the rubber composition after crosslinking) preferably has a breaking strength TB of 35 MPa or less before the thermal aging test. More preferably it is 28 MPa or less, and even more preferably 25 MPa or less. The lower limit is preferably 2 MPa or more, more preferably 8 MPa or more, and even more preferably 12 MPa or more. When it is within the above range, the effect tends to be better obtained.

[0152] In this specification, the elongation at break EB and the strength at break TB are measured by conducting a tensile test at a temperature of 23°C in accordance with JIS K6251:2010 "Vulcanized rubber and thermoplastic rubber - Method for determining tensile properties", and specifically by the method described in the examples.

[0153] Furthermore, the elongation at break EB and strength at break TB of the above rubber composition (the rubber composition after crosslinking) can be adjusted by the type and amount of chemicals (especially rubber components, pyridine compounds represented by general formula (1), divalent or higher carboxylic acid compounds, fillers, and zinc oxide) added to the rubber composition. For example, the elongation at break EB tends to be higher when the amount of pyridine compound added is small, and the strength at break TB tends to be higher when the amount of pyridine compound added is large.

[0154] The above rubber composition is preferably a tire rubber composition, as it can be suitably used in various tire components, for example. The tire components made of the above rubber composition are not particularly limited and include any tire components such as the tread (cap tread, base tread, under tread, etc.), sidewall, wing, bead apex, clinch (clinch apex), chafer (rubber chafer, etc.), inner liner, breaker topping, pry topping, etc. Among these, it is particularly suitable for use in the tread, sidewall, wing, clinch, chafer, etc., from the viewpoint of obtaining better results.

[0155] A tire comprising tire components made of the above-mentioned rubber composition is manufactured using the above-mentioned rubber composition by conventional methods. That is, a rubber composition, which may contain various additives as needed, can be extruded in the unvulcanized stage to match the shape of various tire components, molded in a conventional manner on a tire molding machine, bonded together with other tire components to form an unvulcanized tire, and then heated and pressurized in a vulcanizing machine to manufacture the tire.

[0156] The above-mentioned tires are not particularly limited and include, for example, pneumatic tires, solid tires, and airless tires. Among these, pneumatic tires are preferred.

[0157] The above tires can be used for passenger cars, large passenger cars, large SUVs, heavy-duty trucks and buses, light trucks, motorcycles, racing tires, winter tires (studless tires, snow tires, studded tires), all-season tires, run-flat tires, aircraft tires, mining tires, and more. [Examples]

[0158] The following examples (implementations) are considered preferable for implementation, but the scope of this disclosure is not limited to these examples.

[0159] The various chemicals used in the examples and comparative examples are described below. ENR50: ENR50 manufactured by Kumpulan Guthrie (epoxidation rate: 50 mol%) Dicarboxylic acid: Dodecane dioic acid manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Pyridine compound 1: 4-dimethylaminopyridine manufactured by Tokyo Chemical Industry Co., Ltd. Pyridine compound 2: 2,6-diaminopyridine manufactured by Tokyo Chemical Industry Co., Ltd. Carbon Black: N330 (N2SA: 75m) manufactured by Cabot Japan Co., Ltd. 2 / g) Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Beads of stearic acid manufactured by NOF Corporation Sulfur: HK-200-5 (5% oil-containing powdered sulfur) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator: Noxellar NS (N-tert-butyl-2-benzothiazolyl sulfenamide (TBBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0160] (Examples 1-5) According to the formulation shown in Table 1, the materials were kneaded for 5 minutes at 150°C using a 1.7L Banbury mixer manufactured by Kobe Steel, Ltd. to obtain a kneaded product. This kneaded product was press-molded in a 2mm thick mold at 170°C for 12 minutes to obtain a cross-linked rubber composition (sheet).

[0161] (Example 6 and Comparative Example 1) According to the formulation shown in Table 1, the materials other than sulfur and vulcanization accelerator are kneaded for 5 minutes at 150°C using a 1.7L Banbury mixer manufactured by Kobe Steel, Ltd. to obtain a mixture. Sulfur and vulcanization accelerator are added to the mixture and kneaded for 5 minutes at 80°C using an open roll to obtain an unvulcanized rubber composition. The above unvulcanized rubber composition is press-molded in a 2 mm thick mold at 170°C for 12 minutes to obtain a crosslinked rubber composition (sheet).

[0162] <Thermal aging test> A new (pre-heat-aging) cross-linked rubber sheet is subjected to a heat-aging test (100°C, 7 days) in accordance with JIS K6257:2010 to obtain a cross-linked rubber sheet after heat aging.

[0163] Table 1 shows the results calculated based on the evaluation method below, assuming that the cross-linked rubber sheets obtained from compositions with varying formulations according to Table 1 are used.

[0164] <Tensile Test> Using the cross-linked rubber sheets described above before and after heat aging, a No. 7 dumbbell-shaped rubber test specimen was prepared, and a tensile test was conducted at a temperature of 23°C in accordance with JIS K6251:2010 "Vulcanized rubber and thermoplastic rubber - Method for determining tensile properties," and the elongation at break EB [%] (23°C) and the strength at break TB [MPa] (23°C) were measured. (Conditions for tensile testing) Environmental temperature = 23℃ Testing machine = "Strograph" product name, manufactured by Toyo Seiki Seisakusho Co., Ltd. Tensile speed = 200 mm / min

[0165] Then, the EB change index and TB change index for each formulation are calculated using the following formula. (EB change index) = (EB after thermal aging) / (EB before thermal aging) × 100 (TB change index) = (TB after thermal aging) / (TB before thermal aging) × 100

[0166] The EB change index and TB change index for each formulation calculated from the above are expressed as an index using the following formula, with the EB change index and TB change index of Comparative Example 1 set to 100. (Heat resistance index EB) = (EB change index of each formulation) / (EB change index of Comparative Example 1) × 100 (Heat resistance index TB) = (TB change index of each formulation) / (TB change index of Comparative Example 1) × 100 Next, the sum of the heat resistance index EB and the heat resistance index TB is taken to obtain the heat resistance index. A higher heat resistance index indicates superior heat resistance.

[0167] [Table 1]

[0168] The present invention (1) is a rubber composition comprising a rubber component containing an epoxidized diene rubber, a pyridine compound represented by the following general formula (1), and a carboxylic acid compound with a valency of 2 or higher.

[0169] [ka]

[0170] In formula (1) above, R bonded to the pyridine ring 1 ~R 5 R represents a hydrogen atom or a monovalent organic group, either identical or different. 1 ~R 5 They may be bonded to each other, or they may form a ring structure.

[0171] The present invention (2) further comprises a filler, The rubber composition according to the present invention (1), wherein the content of the filler is 50 parts by mass or more per 100 parts by mass of the rubber component.

[0172] The present invention (3) is the rubber composition according to the present invention (2), wherein the filler contains carbon black.

[0173] The present invention (4) is a rubber composition in which the epoxidized diene rubber is any combination of any of the present inventions (1) to (3), which is an epoxidized isoprene rubber.

[0174] The present invention (5) is a rubber composition that further comprises zinc oxide in any combination with any of the present inventions (1) to (4).

[0175] The present invention (6) relates to the R bonded to the pyridine ring in the general formula (1) 1 ~R 5 The rubber composition is any combination of any of the present inventions (1) to (5), wherein at least one of the is an amino group.

[0176] The present invention (7) is a rubber composition in any combination of any of the present inventions (1) to (6) wherein the elongation EB at break before the heat aging test is 1000% or less.

[0177] The present invention (8) is a rubber composition in any combination of any of the present inventions (1) to (7) having a fracture strength TB of 35 MPa or less before a thermal aging test.

[0178] The present invention (9) is a tire having a tire member made of a rubber composition in any combination of any of the present inventions (1) to (8).

Claims

1. A rubber composition comprising a rubber component containing an epoxidized diene rubber, a pyridine compound represented by the following general formula (1), and a divalent or higher carboxylic acid compound. 【Chemistry 1】 (In formula (1), R bonded to the pyridine ring) １ ~R ５ R represents a hydrogen atom or a monovalent organic group, either identical or different. １ ~R ５ They may be bonded to each other, or they may form a ring structure.

2. Furthermore, it includes a filler, The rubber composition according to claim 1, wherein the content of the filler is 50 parts by mass or more per 100 parts by mass of the rubber component.

3. The rubber composition according to claim 2, wherein the filler comprises carbon black.

4. The rubber composition according to claim 1, wherein the epoxidized diene rubber is an epoxidized isoprene rubber.

5. Furthermore, the rubber composition according to claim 1, further comprising zinc oxide.

6. R bonded to the pyridine ring in the general formula (1) １ ~R ５ The rubber composition according to claim 1, wherein at least one of them is an amino group.

7. A tire having a tire member made of the rubber composition described in claim 1.

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