Compound, rubber composition, and modified diene rubber

Abstract

To provide a compound which can improve low heat build-up properties when added to a diene rubber.SOLUTION: The compound is represented by the following formula (1) (where X represents an anion which forms a salt with pyridinium; R1 and R2 each independently represent a hydrogen atom or a methyl group; and R3 represents an aryl group, an aralkyl group, an alkenyl group, a C4 or higher alkyl group or a monovalent group represented by the following formula which may have a substituent optionally having one or more selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom: -R31-(R32)n-R33 (where R31 represents a C1-3 alkylene group which may have a substituent; R32 represents a divalent group obtained by removing one hydrogen atom from a primary amino group or a secondary amino group, or the like; R33 represents a hydrogen atom or the like; and n represents an integer of 0, 1 or 2)).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a compound, a rubber composition, and a modified diene-based rubber. [Background technology]

[0002] Fillers are compounding agents that are mixed with rubber to reinforce the rubber, increase its volume, or impart special functions. The use of inorganic fillers such as silica is known as a method for obtaining a rubber composition that has a reinforcing effect and low heat buildup, i.e., low loss. The method of using inorganic fillers is applied to rubber compositions for environmentally friendly, fuel-efficient tires.

[0003] When inorganic fillers are compounded into rubber compositions, inorganic fillers, particularly hydrophilic silica with silanol groups on its surface, have low affinity with hydrophobic rubber and tend to aggregate in the rubber composition. Therefore, to enhance the rubber reinforcement properties of the inorganic filler and achieve low heat buildup (low loss), it is necessary to increase the affinity between the inorganic filler and rubber. One known method for achieving this is to use a specific tetrazine compound to impart low heat buildup to a rubber component (see Patent Document 1). Another known method is to use a modified polymer obtained by reacting a conjugated diene polymer containing no tetrasubstituted olefin and / or trisubstituted olefin with a modifier containing a nitrone group and a carboxy group together with a diene rubber (see Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2017 / 057758 [Patent Document 2] International Publication No. 2015 / 114845 Summary of the Invention [Problem to be solved by the invention]

[0005] However, it is expected that public interest in environmental issues such as atmospheric carbon dioxide concentration and air pollution will continue to grow in the future, and there is a demand for technologies that reduce tire rolling resistance and lead to improved fuel efficiency for automobiles. More specifically, there is a demand for technologies that impart even lower loss properties to rubber compositions containing diene rubber and inorganic fillers such as silica, but such demands have not yet been fully met.

[0006] The present invention has been made in view of the above circumstances, and aims to provide a compound that can improve low heat buildup when added to a diene-based rubber, a modified diene-based rubber modified with the compound, and a rubber composition containing the compound or the modified diene-based rubber. [Means for solving the problem]

[0007] As a result of extensive research conducted by the present inventors to achieve the above object, they discovered that a specific compound can improve low heat buildup when added to a diene rubber, and thus completed the present invention.

[0008] That is, the present invention is as follows. [1] A compound represented by the following formula (1): [ka] In formula (1), X represents an anion that forms a salt with pyridinium, R1 and R2 each independently represent a hydrogen atom or a methyl group, and R3 represents an aryl group, an aralkyl group, an alkenyl group, or an alkyl group having 4 or more carbon atoms, which may have a substituent optionally having one or more selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom, or a monovalent group represented by the following formula (7): -R 31 -(R 32 ) n -R 33 (7) (In formula (7), R 31represents an alkylene group having 1 to 3 carbon atoms which may have a substituent which may have one or more atoms selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom, and R 32 represents a divalent group obtained by removing one hydrogen atom from a primary amino group or a secondary amino group, a divalent group obtained by removing one hydrogen atom from the primary amino group or secondary amino group in an aminoalkyl group having a primary amino group or a secondary amino group, an oxycarbonyl group, a carbonyl group, a hydroxyalkylene group, a divalent group obtained by removing one hydrogen atom from the primary amino group or secondary amino group in an amido group having a primary amino group or a secondary amino group, an oxygen atom, a sulfur atom, a divalent heterocyclic group, a divalent epoxy group, an alkyleneoxycarbonyl group, an alkyleneoxy group, an alkylenesulfanyl group, an aryleneoxy group, or an arylenesulfanyl group; R 33 represents a halogen atom, an amino group, an aminoalkyl group, an alkoxycarbonyl group, an acyl group, an acyloxy group, an amido group, a carboxyl group, a carboxyalkyl group, a formyl group, a nitrile group, a nitro group, an alkyl group, a hydroxyalkyl group, a hydroxy group, an alkoxy group, an aryl group, an aryloxy group, a monovalent heterocyclic group, a monovalent epoxy group, a sulfanyl group, an alkylsulfanyl group, or an arylsulfanyl group; n represents 0, 1, or 2; when n represents 2, two R 32 may be the same or different. [2] A compound represented by the following formula (2): [ka] (In formula (2), X represents an anion that forms a salt with pyridinium; R1 and R2 each independently represent a hydrogen atom or a methyl group; and R4 represents a hydrogen atom, or an alkyl group, aryl group, aralkyl group, or alkenyl group, which may have one or more groups selected from the group consisting of a hydroxy group, an alkoxy group, an acyl group, an amino group, an amido group, an epoxy group, a sulfanyl group, and an alkylsulfanyl group.) [3] A compound represented by the following formula (3): [ka] (In formula (3), X represents an anion that forms a salt with pyridinium; R1 and R2 each independently represent a hydrogen atom or a methyl group; Z represents an oxygen atom, a sulfur atom, an alkylene group, or a group represented by -NR6-; and R5 and R6 each independently represent a hydrogen atom, or an alkyl group, aryl group, aralkyl group, or alkenyl group which may have one or more groups selected from the group consisting of a hydroxy group, an alkoxy group, an acyl group, an amino group, an amido group, an epoxy group, a sulfanyl group, and an alkylsulfanyl group.) [4] The compound described above, wherein Z is a group represented by -NR6-. [5] The compound described above, wherein R1 and R2 are hydrogen atoms. [6] A rubber composition comprising the above compound, a diene rubber, and a filler. [7] The rubber composition as described above, wherein the diene rubber comprises at least one rubber selected from the group consisting of styrene-butadiene rubber, butadiene rubber, isoprene rubber, and natural rubber. [8] The above rubber composition, wherein the filler comprises at least one selected from the group consisting of carbon black and silica. [9] The rubber composition further comprising a silane coupling agent.

[10] The above rubber composition further contains sulfur and a vulcanization accelerator.

[11] A modified diene rubber having a modifying group represented by the following formula (4a), (4b), (4c), (4d), (4e), (4f), (4g), (4h), (4i), (4j) or (4k): [ka] (In each formula, X represents an anion that forms a salt with pyridinium, R1 and R2 each independently represent a hydrogen atom or a methyl group, R3 represents an aryl group, an aralkyl group, an alkenyl group, or an alkyl group having 4 or more carbon atoms, which may have a substituent optionally having one or more selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom, or a monovalent group represented by the following formula (7), and the wavy line represents a bonding site of the diene rubber with the modifying group.) -R 31 -(R32 ) n -R 33 (7) (In formula (7), R 31 represents an alkylene group having 1 to 3 carbon atoms which may have a substituent which may have one or more atoms selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom, and R 32 represents a divalent group obtained by removing one hydrogen atom from a primary amino group or a secondary amino group, a divalent group obtained by removing one hydrogen atom from the primary amino group or secondary amino group in an aminoalkyl group having a primary amino group or a secondary amino group, an oxycarbonyl group, a carbonyl group, a hydroxyalkylene group, a divalent group obtained by removing one hydrogen atom from the primary amino group or secondary amino group in an amido group having a primary amino group or a secondary amino group, an oxygen atom, a sulfur atom, a divalent heterocyclic group, a divalent epoxy group, an alkyleneoxycarbonyl group, an alkyleneoxy group, an alkylenesulfanyl group, an aryleneoxy group, or an arylenesulfanyl group; R 33 represents a halogen atom, an amino group, an aminoalkyl group, an alkoxycarbonyl group, an acyl group, an acyloxy group, an amido group, a carboxyl group, a carboxyalkyl group, a formyl group, a nitrile group, a nitro group, an alkyl group, a hydroxyalkyl group, a hydroxy group, an alkoxy group, an aryl group, an aryloxy group, a monovalent heterocyclic group, a monovalent epoxy group, a sulfanyl group, an alkylsulfanyl group, or an arylsulfanyl group; n represents 0, 1, or 2; when n represents 2, two R 32 may be the same or different.

[12] The modified diene rubber, wherein R1 and R2 are hydrogen atoms.

[13] A rubber composition comprising the modified diene rubber and a filler. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a compound that can improve low heat buildup when added to a diene rubber, a modified diene rubber modified with the compound, and a rubber composition containing the compound or the modified diene rubber. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail, but the present invention is not limited to the following embodiment. The present invention can be modified in various ways without departing from the gist of the present invention.

[0011] (compound) The compound of this embodiment is represented by the following formula (1). [ka] In formula (1), X represents an anion that forms a salt with pyridinium, R1 and R2 each independently represent a hydrogen atom or a methyl group, and R3 represents an aryl group, an aralkyl group, an alkenyl group, or an alkyl group having 4 or more carbon atoms, which may have a substituent optionally having one or more selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom, or a monovalent group represented by the following formula (7): -R 31 -(R 32 ) n -R 33 (7) Here, in equation (7), R 31 represents an alkylene group having 1 to 3 carbon atoms which may have a substituent which may have one or more atoms selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom, and R 32represents a divalent group obtained by removing one hydrogen atom from a primary amino group or a secondary amino group (*-NL-: "*" represents the nitrogen atom of the pyridine ring in the above formula (1). The same applies hereinafter. L represents an alkylene group in this paragraph), a divalent group obtained by removing one hydrogen atom from the primary amino group or secondary amino group in an aminoalkyl group having a primary amino group or a secondary amino group (*-L-NR-: R represents a hydrogen atom or an alkyl group in this paragraph), an oxycarbonyl group (*-C(O)O-, *-OC(O)-), a carbonyl group (*-C(O)-), a hydroxyapatite ... an alkylene group (*-L(OH)-), a divalent group obtained by removing one hydrogen atom from a primary amino group or a secondary amino group in an amide group having a primary amino group or a secondary amino group (*-C(O)-NR-), an oxygen atom, a sulfur atom, a divalent heterocyclic group, a divalent epoxy group, an alkyleneoxycarbonyl group (*-L-COO-), an alkyleneoxy group (*-LO-), an alkylenesulfanyl group (*-LS-), an aryleneoxy group (*-Ar-O-: Ar represents an arylene group in this paragraph), or an arylenesulfanyl group (*-Ar-S-); R 33 represents a halogen atom, an amino group (-NR2), an aminoalkyl group (-L-NR2), an alkoxycarbonyl group or a carboxyl group (-C(O)OR), an acyl group or a formyl group (-C(O)R), an acyloxy group (-OC(O)R), an amide group (-C(O)NR2), a carboxyalkyl group (-LC(O)OH), a nitrile group, a nitro group, an alkyl group, a hydroxyalkyl group (-L-OH), a hydroxy group, an alkoxy group, an aryl group, an aryloxy group (-O-Ar), a monovalent heterocyclic group, a monovalent epoxy group, a sulfanyl group (-SH), an alkylsulfanyl group (-SR), or an arylsulfanyl group (-S-Ar); n represents 0, 1, or 2; when n represents 2, two R 32 may be the same or different from each other.

[0012] From the viewpoint of more effectively and reliably achieving the effects of the present invention, R 32is preferably a divalent group obtained by removing one hydrogen atom from a primary amino group or a secondary amino group, a divalent group obtained by removing one hydrogen atom from a primary amino group or a secondary amino group in an aminoalkyl group having a primary amino group or a secondary amino group, an oxycarbonyl group, a carbonyl group, a hydroxyalkylene group, a divalent group obtained by removing one hydrogen atom from a primary amino group or a secondary amino group in an amido group having a primary amino group or a secondary amino group, an oxygen atom, a sulfur atom, a divalent heterocyclic group, a divalent epoxy group, an aryleneoxy group, or an arylenesulfanyl group; 33 is preferably a halogen atom, an amino group, an aminoalkyl group, an alkoxycarbonyl group or a carboxyl group, an acyl group or a formyl group, an acyloxy group, an amido group, a nitrile group, a nitro group, an alkyl group, a hydroxy group, an alkoxy group, an aryl group, an aryloxy group, a monovalent heterocyclic group, a monovalent epoxy group, a sulfanyl group, an alkylsulfanyl group, or an arylsulfanyl group.

[0013] When R3 as a whole is an alkyl group which may have a substituent, the alkyl group is preferably an alkyl group having 1 to 18 carbon atoms, and more preferably an alkyl group having 1 to 12 carbon atoms, from the viewpoint of more effectively and reliably achieving the effects of the present invention. Examples of such alkyl groups include linear or branched alkyl groups having 1 to 12 carbon atoms, and more preferably having 1 to 8 carbon atoms. More specific examples include linear or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, 1-ethylpropyl, n-pentyl, neopentyl, n-hexyl, isohexyl, 3-methylpentyl, and n-octyl; and cyclic alkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl.

[0014] When R3 is an aryl group which may have a substituent as a whole, the aryl group is preferably an aryl group having 6 to 14 carbon atoms, from the viewpoint of more effectively and reliably achieving the effects of the present invention. Examples of such aryl groups include a phenyl group, a biphenyl group, a naphthyl group, a dihydroindenyl group, and a 9H-fluorenyl group. Of these, a phenyl group and a naphthyl group are more preferred, and a phenyl group is even more preferred. Phenyl groups which have a substituent are also preferred.

[0015] When R3 as a whole is an aralkyl group which may have a substituent, the aralkyl group is preferably an aralkyl group having 7 to 20 carbon atoms, from the viewpoint of more effectively and reliably achieving the effects of the present invention. Examples of such aralkyl groups include a benzyl group, a phenethyl group, a trityl group, a 1-naphthylmethyl group, a 2-(1-naphthyl)ethyl group, and a 2-(2-naphthyl)ethyl group. Of these, a benzyl group and a phenethyl group are more preferred, and a benzyl group is even more preferred.

[0016] When R3 as a whole is an alkenyl group which may have a substituent, the alkenyl group is preferably an alkenyl group having 2 to 18 carbon atoms, from the viewpoint of more effectively and reliably achieving the effects of the present invention. Examples of such alkenyl groups include alkenyl groups having 2 to 6 carbon atoms, and specific examples include vinyl, 1-propenyl, allyl, isopropenyl, 1-butenyl, and 2-butenyl groups.

[0017] When R3 as a whole is an alkyl group, aryl group, aralkyl group, or alkenyl group which may have a substituent, examples of the substituent include a halogen atom, an amino group, an aminoalkyl group, an alkoxycarbonyl group, an acyl group, an acyloxy group, an amido group, a carboxyl group, a carboxyalkyl group, a formyl group, a nitrile group, a nitro group, an alkyl group, a hydroxyalkyl group, a hydroxy group, an alkoxy group, an aryl group, an aryloxy group, a monovalent heterocyclic group, a monovalent epoxy group, a sulfanyl group, an alkylsulfanyl group, and an arylsulfanyl group. The number of substituents in R3 may be preferably 1 to 5, and more preferably 1 to 3.

[0018] Examples of the halogen atom as a substituent include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0019] The amino group as a substituent includes not only an amino group represented by -NH2 but also substituted amino groups such as linear or branched monoalkylamino groups having 1 to 6 carbon atoms (particularly 1 to 4 carbon atoms), such as a methylamino group, ethylamino group, n-propylamino group, isopropylamino group, n-butylamino group, isobutylamino group, s-butylamino group, t-butylamino group, 1-ethylpropylamino group, n-pentylamino group, neopentylamino group, n-hexylamino group, isohexylamino group, and 3-methylpentylamino group; and dialkylamino groups having two linear or branched alkyl groups having 1 to 6 carbon atoms (particularly 1 to 4 carbon atoms), such as a dimethylamino group, ethylmethylamino group, and diethylamino group.

[0020] Examples of the aminoalkyl group as a substituent include aminoalkyl groups having 1 to 4 carbon atoms, such as an aminomethyl group, a 2-aminoethyl group, and a 3-aminopropyl group.

[0021] Examples of the alkoxycarbonyl group as a substituent include alkoxycarbonyl groups having 1 to 4 carbon atoms in the alkoxy group, such as a methoxycarbonyl group and an ethoxycarbonyl group.

[0022] Examples of the acyl group as a substituent include linear or branched alkylcarbonyl groups having 1 to 4 alkyl carbon atoms, such as an acetyl group, a propionyl group, and a pivaloyl group.

[0023] Examples of the acyloxy group as a substituent include alkylcarbonyloxy groups having 1 to 4 alkyl carbon atoms, such as an acetyloxy group, a propionyloxy group, and an n-butyryloxy group.

[0024] Examples of the amide group as a substituent include carboxylic acid amide groups having 2 to 8 carbon atoms, such as an acetamide group and a benzamide group; thioamide groups having 2 to 8 carbon atoms, such as a thioacetamide group and a thiobenzamide group; and N-substituted amide groups having 2 to 8 carbon atoms, such as an N-methylacetamide group and an N-benzylacetamide group.

[0025] Examples of the carboxyalkyl group as a substituent include carboxy-alkyl groups having 1 to 6 alkyl carbon atoms, such as a carboxymethyl group, a carboxyethyl group, a carboxy-n-propyl group, a carboxy-n-butyl group, a carboxy-n-butyl group, and a carboxy-n-hexyl group.

[0026] Examples of the hydroxyalkyl group as a substituent include hydroxyalkyl groups having 1 to 6 carbon atoms, such as a hydroxymethyl group, a hydroxyethyl group, a hydroxy-n-propyl group, and a hydroxy-n-butyl group.

[0027] Examples of the alkoxy group as a substituent include linear, branched, and cyclic alkoxy groups. More specifically, examples include linear or branched alkoxy groups having 1 to 6 carbon atoms (preferably 1 to 4 carbon atoms), such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, t-butoxy, n-pentyloxy, neopentyloxy, and n-hexyloxy groups; and cyclic alkoxy groups having 3 to 8 carbon atoms (preferably 3 to 6 carbon atoms), such as cyclopropyloxy, cyclobutyloxy, cyclopentyloxy, cyclohexyloxy, cycloheptyloxy, and cyclooctyloxy groups.

[0028] Examples of the aryloxy group as a substituent include aryloxy groups having 6 to 14 carbon atoms, such as a phenoxy group, a biphenyloxy group, and a naphthoxy group.

[0029] From the viewpoint of more effectively and reliably achieving the effects of the present invention, the monovalent heterocyclic group as a substituent preferably has the number of atoms constituting the heterocycle (number of ring members) of 4 to 14, more preferably 5 to 10. Examples of such monovalent heterocyclic groups include a 2-pyridyl group, a 3-pyridyl group, a 4-pyridyl group, a 2-pyrazinyl group, a 2-pyrimidyl group, a 4-pyrimidyl group, a 5-pyrimidyl group, a 3-pyridazyl group, a 4-pyridazyl group, a 4-(1,2,3-triazyl) group, a 5-(1,2,3-triazyl) group, a 2-(1,3,5-triazyl) group, a 3-(1,2,4-triazyl) group, a 5-(1,2,4-triazyl) group, a 6-(1,2,4-triazyl) group, 2-quinolyl group, 3-quinolyl group, 4-quinolyl group, 5-quinolyl group, 6-quinolyl group, 7-quinolyl group, 8-quinolyl group, 1-isoquinolyl group, 3-isoquinolyl group, 4-isoquinolyl group, 5-isoquinolyl group, 6-isoquinolyl group, 7-isoquinolyl group, 8-isoquinolyl group, 2-quinoxalyl group, 3-quinoxalyl group, 5-quinoxalyl group, 6-quinoxalyl group, 7-quinoxalyl group, 8-quinoxalyl group, 3-cinnolyl group, 4-cinnolyl group, 5-cinnolyl group, 6-cinnolyl group, 7-cinnolyl group, 8-cinnolyl group, 2-quinazolyl group, 4-quinazolyl group, 5-quinazolyl group, 6-quinazolyl group, 7-quinazolyl group, 8-quinazolyl group, 1-phthalazyl group, 4-phthalazyl group, 5-phthalazyl group, 6-phthalazyl group, 7-phthalazyl group, 8-phthalazyl group, 1-tetrahydroquinolyl group, 2-tetrahydroquinolyl group, 3-tetrahydroquinolyl group, 4-tetrahydroquinolyl group, 5-tetrahydroquinolyl group, 6-tetrahydroquinolyl group, 7-tetrahydroquinolyl group, 8-tetrahydroquinolyl group, 1-pyrrolyl group, 2-pyrrolyl group, 3-pyrrolyl group, 2-furyl group , 3-furyl group, 2-thienyl group, 3-thienyl group, 1-imidazolyl group, 2-imidazolyl group, 4-imidazolyl group, 5-imidazolyl group, 1-pyrazolyl group, 3-pyrazolyl group, 4-pyrazolyl group, 5-pyrazolyl group, 2-oxazolyl group, 4-oxazolyl group, 5-oxazolyl group, 2-thiazolyl group, 4-thiazolyl group, 5-thiazolyl group, 3-isoxazolyl group, 4-isoxazolyl group, 5-isoxazolyl group, 3-isothiazolyl group, 4-isothiazolyl group, 5-isothiazolyl group, 4-(1,2,3-thiadiazolyl) group, 5-(1, 2,3-thiadiazolyl group, 3-(1,2,5-thiadiazole) group, 2-(1,3,4-thiadiazole) group, 4-(1,2,3-oxadiazolyl) group, 5-(1,2,3-oxadiazolyl) group, 3-(1,2,4-oxadiazolyl) group, 5-(1,2,4-oxadiazolyl) group, 3-(1,2,5-oxadiazolyl) group, 2-(1,3,4-oxadiazolyl) group, 1-(1,2,3-triazolyl) group, 4-(1,2,3-triazolyl) group, 5-(1,2,3-triazolyl) group, 1-(1,2,4-triazolyl) group, 3-(1,2,4-triazolyl) group, 5-(1,2,4-triazolyl) group, 1-tetrazolyl group, 5-tetrazolyl group, 1-indolyl group, 2-indolyl group, 3-indolyl group, 4-indolyl group, 5-indolyl group, 6-indolyl group, 7-indolyl group, 1-isoindolyl group, 2-isoindolyl group, 3-isoindolyl group, 4-isoindolyl group, 5-isoindolyl group, 6-isoindolyl group, 7-isoindolyl group, 1-benzimidazolyl group, 2-benzimidazolyl group, 4-benzimidazolyl group, 5- Benzimidazolyl group, 6-benzimidazolyl group, 7-benzimidazolyl group, 2-benzofuranyl group, 3-benzofuranyl group, 4-benzofuranyl group, 5-benzofuranyl group, 6-benzofuranyl group, 7-benzofuranyl group, 1-isobenzofuranyl group, 3-isobenzofuranyl group, 4-isobenzofuranyl group, 5-isobenzofuranyl group, 6-isobenzofuranyl group, 7-isobenzofuranyl group, 2-benzothienyl group, 3-benzothienyl group, 4-benzothienyl group, 5-benzothienyl group, 6-benzothienyl group nyl group, 7-benzothienyl group, 2-benzoxazolyl group, 4-benzoxazolyl group, 5-benzoxazolyl group, 6-benzoxazolyl group, 7-benzoxazolyl group, 2-benzothiazolyl group, 4-benzothiazolyl group, 5-benzothiazolyl group, 6-benzothiazolyl group, 7-benzothiazolyl group, 1-indazolyl group, 3-indazolyl group, 4-indazolyl group, 5-indazolyl group, 6-indazolyl group, 7-indazolyl group, 2-morpholyl group, 3-morpholyl group, 4-morpholyl group, 1-piperyl group Examples of the alkyl group include pyrazyl, 2-piperazyl, 1-piperidyl, 2-piperidyl, 3-piperidyl, 4-piperidyl, 2-tetrahydropyranyl, 3-tetrahydropyranyl, 4-tetrahydropyranyl, 2-tetrahydrothiopyranyl, 3-tetrahydrothiopyranyl, 4-tetrahydrothiopyranyl, 1-pyrrolidyl, 2-pyrrolidyl, 3-pyrrolidyl, 2-tetrahydrofuranyl, 3-tetrahydrofuranyl, 2-tetrahydrothienyl, and 3-tetrahydrothienyl. Among these, pyridyl, furanyl, thienyl, pyrimidyl, and pyrazyl groups are more preferred, and pyridyl is particularly preferred.

[0030] Examples of the alkylsulfanyl group as a substituent include those in which the oxygen atom of the above alkoxy group is substituted with a sulfur atom. Also, examples of the arylsulfanyl group as a substituent include those in which the oxygen atom of the above aryloxy group is substituted with a sulfur atom. Examples of the alkyl and aryl groups as substituents are the same as those exemplified above, and therefore, further explanation will be omitted here.

[0031] X is not particularly limited as long as it is an anion capable of forming a salt with pyridinium. Examples of X include halide ions such as chloride ion, bromide ion, and iodide ion; C1-4 alkyl sulfate ions such as methyl sulfate ion, ethyl sulfate ion, propyl sulfate ion, and butyl sulfate ion; hydrocarbon sulfonate ions such as methanesulfonate ion, ethanesulfonate ion, propanesulfonate ion, butanesulfonate ion, and tosyl ion; phosphate ion; nitrate ion; and organic acid ions such as acetate ion and lactate ion. Among these, from the viewpoint of more effectively and reliably achieving the effects of the present invention, halide ions and organic acid ions are preferred, and chloride ion, bromide ion, iodide ion, and acetate ion are more preferred.

[0032] The compound of this embodiment is preferably a compound represented by the following formula (2), from the viewpoint of more effectively and reliably exhibiting the effects of the present invention. [ka] In formula (2), X represents an anion that forms a salt with pyridinium, R1 and R2 each independently represent a hydrogen atom or a methyl group, and R4 represents a hydrogen atom, or an alkyl group, aryl group, aralkyl group, or alkenyl group, which may have one or more groups selected from the group consisting of a hydroxy group, an alkoxy group, an acyl group, an amino group, an amido group, an epoxy group, a sulfanyl group, and an alkylsulfanyl group.

[0033] X has the same meaning as in the above formula (1), and the examples and preferred embodiments are the same as those in the above formula (1), so the explanation here will be omitted.

[0034] Preferred embodiments and examples of the alkyl group, aryl group, aralkyl group, and alkenyl group in R4, as well as the alkoxy group, acyl group, amino group, amido group, and alkylsulfanyl group that are substituents thereon, are the same as those in R3, and therefore further explanation is omitted here. However, when R3 in the above formula (1) has —CH2—CH(OH)— (wherein a methylene group is bonded to the nitrogen atom) bonded to the nitrogen atom of the pyridine ring shown in formula (1), R4 differs from R3 in that it does not have this group.

[0035] The compound of this embodiment is more preferably a compound represented by the following formula (3), from the viewpoint of more effectively and reliably exhibiting the effects of the present invention. [ka] In formula (3), X represents an anion that forms a salt with pyridinium, and R1 and R2 each independently represent a hydrogen atom or a methyl group. Z represents an oxygen atom, a sulfur atom, an alkylene group, or a group represented by -NR6-, where the alkylene group has, for example, 1 to 10 carbon atoms. R5 and R6 each independently represent a hydrogen atom, or an alkyl group, aryl group, aralkyl group, or alkenyl group which may have one or more groups selected from the group consisting of a hydroxy group, an alkoxy group, an acyl group, an amino group, an amido group, an epoxy group, a sulfanyl group, and an alkylsulfanyl group, and are preferably hydrogen atoms in order to more effectively and reliably exhibit the effects of the present invention.

[0036] X has the same meaning as in the above formula (1), and the examples and preferred embodiments are the same as those in the above formula (1), so the explanation here will be omitted.

[0037] Preferred embodiments and examples of the alkyl group, aryl group, aralkyl group, and alkenyl group in R5 and R6, and the alkoxy group, acyl group, amino group, amido group, and alkylsulfanyl group that are substituents thereon, are the same as those for R3, and therefore, description thereof will be omitted here. However, when R3 in the above formula (1) has —CH2C(═O)Z— (wherein a methylene group is bonded to the nitrogen atom) bonded to the nitrogen atom of the pyridine ring, R5 differs from R3 in that it does not have said —CH2C(═O)Z—.

[0038] Regarding the combination of Z and R5, when Z is an oxygen atom or a sulfur atom, examples of R5 include an alkyl group, an aryl group, and an alkoxy group. When Z is an alkylene group, examples of R5 include an alkyl group. When Z is a group represented by -NR6-, examples of R5 and R6 each independently include a hydrogen atom, an alkyl group, an aryl group, and an alkoxy group.

[0039] The compound of this embodiment can be synthesized by the method described in the Examples or by a method based on the method.

[0040] (Modified diene rubber) The modified diene rubber of this embodiment is a modified diene rubber having a modifying group represented by the following formula (4a), (4b), (4c), (4d), (4e), (4f), (4g), (4h), (4i), (4j), or (4k) (hereinafter, these modifying groups are collectively referred to as "modifying groups (4a) to (4k)"). [ka] In each formula, X represents an anion that forms a salt with pyridinium, R1 and R2 each independently represent a hydrogen atom or a methyl group, R3 represents an aryl group, an aralkyl group, or an alkenyl group, or an alkyl group having 4 or more carbon atoms, which may have a substituent optionally having one or more selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom, or a monovalent group represented by the above formula (7), R represents a halogen atom or an alkyl group, and the wavy line represents the bonding site with the above modifying group of the diene rubber.

[0041] X and R3 have the same meanings as in the above formula (1), and are the same examples and preferred embodiments as in the above formula (1), so the explanation here will be omitted.

[0042] The preferred embodiments and examples of the alkyl group in R are the same as those in R3, and therefore, the explanation will be omitted here.

[0043] The modified diene rubber having modifying groups (4a) to (4k) can be obtained by allowing an inverse electron demand Aza-Diels-Alder reaction to proceed between the compound represented by the above formula (1) (hereinafter also referred to as "compound (1)") and a double bond in the diene rubber.

[0044] Specifically, the reaction shown in the following scheme (7), (8), (9) or (10) proceeds, whereby compound (1) is bonded to the double bond site of the diene rubber to form a six-membered ring structure, thereby producing a modified diene rubber. <Scheme (7)> [ka] Here, X, R1, R2 and R3 in each formula have the same meanings as in the above formula (1), and are the same examples and preferred embodiments as in the above formula (1), so explanations here will be omitted.

[0045] In the above scheme (7), the double bond site of the diene rubber represented by formula (1A) undergoes an inverse electron demand Aza-Diels-Alder reaction with compound (1) to form a bicyclo ring structure represented by formula (1B). The -N=N- moiety in this bicyclo ring structure is easily denitrified to form a structure represented by formula (1C1), (1C2) or (1C3), which is further oxidized by oxygen in the air to produce a modified polymer having a structure represented by formula (4a). <Scheme (8)> [ka] Here, X, R1, R2 and R3 in each formula have the same meanings as in the above formula (1), and are the same examples and preferred embodiments as in the above formula (1), so explanations here will be omitted.

[0046] In the above scheme (8), similarly to scheme (7), a bicyclo ring structure represented by formula (1E1) or (1E2) and then a structure represented by formula (1F1), (1F2), (1F3), (1F4), (1F5) or (1F6) are formed from the double bond site of the diene rubber represented by formula (1D) and compound (1), and then a modified diene rubber having a structure represented by formula (4b) or (4c) is produced. <Scheme 9> [ka] Here, X, R1, R2, and R3 in each formula have the same meanings as those in the above formula (1), and are the same examples and preferred embodiments as those in the above formula (1), so explanations here will be omitted. Furthermore, preferred embodiments and examples of the alkyl group in R in each formula are the same as those in R3, so explanations here will be omitted.

[0047] In scheme (9), a bicyclo ring structure represented by formula (1H1) or (1H2) is formed by an inverse electron demand Aza-Diels-Alder reaction between the double bond site of the diene rubber represented by formula (1G) and compound (1), followed by denitrification to produce a modified diene rubber having a structure represented by formula (4d), (4e), (4f), or (4g). When R at the double bond site of the diene rubber represented by formula (1G) is a halogen atom, elimination of the halogen atom may occur, in which case a modified diene rubber having a structure represented by formula (4a) is produced by an oxidation reaction. <Scheme 10> [ka] Here, X, R1, R2, and R3 in each formula have the same meanings as those in the above formula (1), and are the same examples and preferred embodiments as those in the above formula (1), so explanations here will be omitted. Furthermore, preferred embodiments and examples of the alkyl group in R in each formula are the same as those in R3, so explanations here will be omitted.

[0048] In scheme (9), as in scheme 8, a bicyclo ring structure represented by formula (1J1) or (1J2) is formed by reacting the double bond site of the diene rubber represented by formula (1I) with compound (1), and then a modified diene rubber having a structure represented by formula (4h), (4i), (4j) or (4k) is produced. Note that when R at the double bond site of the diene rubber represented by formula (1I) is a halogen atom, elimination of the halogen atom may occur, and in that case, a modified diene rubber having a structure represented by formula (4a) is produced by an oxidation reaction.

[0049] From the viewpoint of more effectively and reliably achieving the effects of the present invention, the modified diene rubber of the present embodiment is preferably a modified diene rubber having a modifying group represented by the following formula (5a), (5b), (5c), (5d), (5e), ​​(5f), (5g), (5h), (5i), (5j) or (5k). [ka] In each formula, X represents an anion that forms a salt with pyridinium, R1 and R2 each independently represent a hydrogen atom or a methyl group, R4 represents a hydrogen atom, or an alkyl group, aryl group, aralkyl group or alkenyl group which may have one or more selected from the group consisting of a hydroxy group, an alkoxy group, an acyl group, an amino group, an amide group, an epoxy group, a sulfanyl group and an alkylsulfanyl group, R represents a halogen atom or an alkyl group, and the wavy line represents the bonding site of the diene rubber with the modifying group.

[0050] X and R4 have the same meanings as in the above formula (2), and are the same examples and preferred embodiments as in the above formula (2), so the explanation here will be omitted.

[0051] The preferred embodiments and examples of the alkyl group in R are the same as those in R3, and therefore, the explanation will be omitted here.

[0052] From the viewpoint of more effectively and reliably achieving the effects of the present invention, the modified diene rubber of the present embodiment is preferably a modified diene rubber having a modifying group represented by the following formula (6a), (6b), (6c), (6d), (6e), (6f), (6g), (6h), (6i), (6j) or (6k). [ka] In each formula, X represents an anion that forms a salt with pyridinium, R1 and R2 each independently represent a hydrogen atom or a methyl group, Z represents an oxygen atom, a sulfur atom, an alkylene group, or a group represented by -NR6-, R5 and R6 each independently represent a hydrogen atom, or an alkyl group, aryl group, aralkyl group, or alkenyl group which may have one or more selected from the group consisting of a hydroxy group, an alkoxy group, an acyl group, an amino group, an amide group, an epoxy group, a sulfanyl group, and an alkylsulfanyl group, R represents a halogen atom or an alkyl group, and the wavy line represents the bonding site with the above-mentioned modifying group of the diene rubber.

[0053] X, R5 and R6 have the same meanings as in the above formula (3), and are the same examples and preferred embodiments as in the above formula (3), so the explanation here will be omitted.

[0054] The preferred embodiments and examples of the alkyl group in R are the same as those in R3, and therefore, the explanation will be omitted here.

[0055] The diene rubber constituting the portion other than the modifying group of the modified diene rubber of this embodiment includes synthetic rubber and natural rubber. Examples of synthetic rubber include styrene-butadiene copolymer rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), nitrile rubber (NBR), chloroprene rubber (CR), ethylene-propylene-diene terpolymer rubber (EPDM), styrene-isoprene-styrene triblock copolymer (SIS), and styrene-butadiene-styrene triblock copolymer (SBS).

[0056] The natural rubber may be any rubber having a carbon-carbon double bond, such as natural rubber latex, technically graded rubber (TSR), smoked sheet (RSS), gutta percha, eucommia-derived natural rubber, guayule-derived natural rubber, and Russian dandelion-derived natural rubber. Furthermore, modified natural rubbers such as methacrylic acid-modified natural rubber and styrene-modified natural rubber, which are obtained by modifying these natural rubbers, are also encompassed by the natural rubber of this embodiment.

[0057] Among these, SBR, BR, IR, and natural rubber are preferred from the viewpoint of more effectively and reliably achieving the effects of the present invention. These diene rubbers may be modified with a modifying group other than the above-mentioned modifying groups (hereinafter referred to as "other modifying groups"). The portion modified with the other modifying group may be the main chain, one end, or both ends. Examples of other modifying groups include epoxy groups, amino groups, alkoxysilyl groups, and hydroxyl groups. These other modifying groups may be used alone or in combination of two or more.

[0058] The weight average molecular weight of the diene rubber is not particularly limited, and may be, for example, 2.0×10 5 ~2.0×10 6 The weight average molecular weight (Mw) is measured in terms of standard polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.

[0059] The method for producing the diene rubber is not particularly limited, and examples thereof include emulsion polymerization, solution polymerization, radical polymerization, anionic polymerization, and cationic polymerization.

[0060] The synthesis conditions for synthesizing the modified diene rubber of this embodiment are not particularly limited. For example, when synthesizing the modified diene rubber, if the diene rubber is solid, the modified diene rubber can be obtained by kneading the compound (1) with the diene rubber. When synthesizing the modified diene rubber, if the diene rubber is liquid, the modified diene rubber can be obtained by mixing a solution or suspension of the diene rubber with the compound (1).

[0061] The heating temperature when synthesizing the modified diene rubber is not particularly limited. For example, in the case of the kneading method described above, the upper limit of the temperature is preferably 80°C or higher and 180°C or lower, and more preferably 100°C or higher and 160°C or lower.

[0062] The kneading or mixing time when synthesizing the modified diene rubber is not particularly limited. For example, in the case of a kneading method, the kneading time is preferably 30 seconds or more and 600 seconds or less, and more preferably 60 seconds or more and 300 seconds or less.

[0063] The amount of compound (1) used when synthesizing the modified diene rubber of this embodiment is preferably 0.1% by mass or more and 5.0% by mass or less, and more preferably 0.3% by mass or more and 3.0% by mass or less, relative to 100% by mass of the diene rubber.

[0064] (Rubber composition containing compound (1)) An example of the rubber composition of this embodiment (hereinafter referred to as the "first rubber composition") contains the compound (1), a diene rubber, and a filler. The compound (1) and the diene rubber are as described above, so a description thereof will be omitted here.

[0065] From the viewpoint of more effectively and reliably achieving the effects of the present invention, the amount of compound (1) in the first rubber composition is preferably 0.1% by mass or more and 5.0% by mass or less, and more preferably 0.3% by mass or more and 3.0% by mass or less, relative to 100% by mass of the diene rubber.

[0066] From the viewpoint of achieving a higher rubber reinforcing effect and further improving low heat buildup, the filler contained in the first rubber composition preferably contains at least one type selected from the group consisting of inorganic fillers and carbon black, but the filler is not limited thereto. The inorganic fillers may be used alone or in combination of two or more types.

[0067] The inorganic filler contains at least one solid particle selected from the group consisting of oxides or hydroxides of silicon, main group metals, or transition metals, and their hydrates, as well as carbonates of these metals. Examples of inorganic fillers include silica; alumina (Al2O3) such as γ-alumina and α-alumina; alumina monohydrate (Al2O3·H2O) such as boehmite and diaspore; aluminum hydroxide [Al(OH)3] such as gibbsite and bayerite; aluminum carbonate [Al2(CO3)2]; magnesium hydroxide [Mg(OH)2]; magnesium oxide (MgO); magnesium carbonate (MgCO3); talc (3MgO·4SiO2·H2O), attapulgite (5MgO·8SiO2·9H2O), titanium dioxide (TiO2), and titanium black (TiO 2n-1), calcium oxide (CaO), calcium hydroxide [Ca(OH)2], magnesium aluminum oxide (MgO·Al2O3), clay (Al2O3·2SiO2), kaolin (Al2O3·2SiO2·2H2O), pyrophyllite (Al2O3·4SiO2·H2O), bentonite (Al2O3·4SiO2·2H2O), aluminum silicates (clay; e.g., Al2SiO5, Al4·3SiO4·5H2O), magnesium silicates (talc; e.g., Mg2SiO4, MgSiO3), silicates Examples of inorganic fillers include calcium (e.g., Ca2·SiO4), aluminum calcium silicate (e.g., Al2O3·CaO·2SiO2), magnesium calcium silicate (CaMgSiO4), calcium carbonate (CaCO3), zirconium oxide (ZrO2), zirconium hydroxide [ZrO(OH)2·nH2O], zirconium carbonate [Zr(CO3)2], zinc acrylate, zinc methacrylate, and crystalline aluminosilicates containing hydrogen, alkali metals, or alkaline earth metals to compensate for the charge, such as various zeolites. These inorganic fillers may have their surfaces organically treated to improve their affinity with diene rubbers.

[0068] Among the above fillers, the inorganic filler preferably contains silica, from the viewpoint of obtaining a higher rubber reinforcing effect and further improving low heat generation. Examples of silica include wet silica, dry silica, and colloidal silica, and wet silica is more preferred from the same viewpoint as above. The silica may be subjected to an organic treatment on its surface to improve its affinity with diene rubber.

[0069] The BET specific surface area of ​​silica is not particularly limited, and for example, 2 / g or more 350m 2 / g or less. By having the BET specific surface area within the above range, both the reinforcing effect of the rubber and the dispersibility of the silica in the diene rubber can be achieved at a higher level. From the same viewpoint, the BET specific surface area of ​​the silica is preferably 80 to 300 m 2 / g is more preferable, and 100m 2 / g or more 270m 2 / g or less is more preferable. 2 / g or more 270m 2 It is more preferable that the BET specific surface area is not more than 1 / g. The BET specific surface area is measured in accordance with ISO 5794 / 1.

[0070] An example of a commercially available product of this type of silica is "HD165MP" (BET specific surface area = 165 m) manufactured by Quechen Silicon Chemical Co., Ltd. 2 / g), product name "HD115MP" (BET specific surface area = 115m 2 / g), product name "HD200MP" (BET specific surface area = 200m 2 / g), product name "HD250MP" (BET specific surface area = 250m 2 / g), and the product name "Nipsil AQ" manufactured by Tosoh Silica Corporation (BET specific surface area = 205 m 2 / g), product name "Nipsil KQ" (BET specific surface area = 240 m 2 / g), and the product name "Ultrasil VN3" manufactured by Degussa (BET specific surface area = 175 m 2 / g) etc.

[0071] When the first rubber composition contains an inorganic filler, preferably silica, together with compound (1), the dispersibility of the inorganic filler is significantly improved, and the low heat buildup of the rubber composition can be further improved.

[0072] The filler contained in the first rubber composition may contain carbon black. By using carbon black, the electrical resistance of the rubber composition can be reduced, the effect of suppressing static electricity can be enhanced, and the rubber strength can also be further increased. There are no particular limitations on the carbon black, and for example, commercially available carbon black may be used.

[0073] More specifically, the carbon black may be high-, medium-, or low-structure SAF, ISAF, IISAF, N110, N134, N220, N234, N330, N339, N375, N550, HAF, FEF, GPF, or SRF grade carbon black, of which SAF, ISAF, IISAF, N134, N234, N330, N339, N375, HAF, or FEF grade carbon black is preferred.

[0074] From the viewpoint of more effectively and reliably achieving the effects of the present invention and the effects of using the filler, the amount of filler mixed in the rubber composition is preferably 20 parts by mass or more and 120 parts by mass or less, and more preferably 50 parts by mass or more and 100 parts by mass or less, per 100 parts by mass of diene rubber. In this embodiment, particularly by using compound (1), the coagulant of the filler can be suppressed even if the amount of filler mixed is increased compared to conventional methods, thereby further improving low heat buildup and rubber reinforcement.

[0075] The first rubber composition of the present embodiment preferably contains a silane coupling agent from the viewpoint of further enhancing the bonding strength between the filler and the diene rubber.

[0076] The silane coupling agent is not particularly limited, but examples thereof include bis-(3-triethoxysilylpropyl)tetrasulfide, bis-(3-trimethoxysilylpropyl)tetrasulfide, bis-(3-methyldimethoxysilylpropyl)tetrasulfide, bis-(2-triethoxysilylethyl)tetrasulfide, bis-(3-triethoxysilylpropyl)disulfide, bis-(3-trimethoxysilylpropyl)disulfide, bis-(3-triethoxysilylpropyl) (propyl) trisulfide, 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltriethoxysilane, 3-lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane, 3-hexanoylthiopropyltrimeth hydroxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2-octanoylthioethyltrimethoxysilane, 2-decanoylthioethyltrimethoxysilane, 2-lauroylthioethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide, and 3-trimethoxysilylpropyl methacryloyl monosulfide.

[0077] When the rubber composition contains a silane coupling agent, the amount of the silane coupling agent is preferably 1 part by mass or more and 20 parts by mass per 100 parts by mass of the filler, from the viewpoint of further enhancing the effect of using the silane coupling agent while further suppressing the decrease in the effect of using other materials.

[0078] The first rubber composition of this embodiment may contain compounding agents commonly used in the rubber industry, such as antioxidants, softeners, vulcanization accelerators, vulcanization accelerator aids, and vulcanizing agents, selected appropriately within the scope that does not impair the object of this embodiment. Among these, it is preferable that the first rubber composition contains a vulcanization accelerator and a vulcanizing agent, and it is more preferable that it contains a vulcanization accelerator and sulfur, which is a type of vulcanizing agent. Commercially available products can be suitably used as these compounding agents.

[0079] The type of antioxidant is not particularly limited, but examples include naphthylamines, p-phenylenediamines, hydroquinone derivatives, bis-, tris-, polyphenols, diphenylamines, quinolines, monophenols, thiobisphenols, and hindered phenols. Among these, p-phenylenediamine and diphenylamine amine antioxidants are preferred from the viewpoint of enhanced antioxidant effect. Examples of diphenylamine antioxidants include 4,4'-(α-methylbenzyl)diphenylamine, 4,4'-(α,α-dimethylbenzyl)diphenylamine, p-(p-toluene-sulfonylamido)diphenylamine, and 4,4'-dioctyldiphenylamine. Among these, 4,4'-(α-methylbenzyl)diphenylamine is particularly preferred from the viewpoint of enhanced antioxidant effect. Furthermore, examples of p-phenylenediamine-based antioxidants include N,N'-diphenyl-p-phenylenediamine, N-isopropyl-N'-phenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, N-phenyl-N'-(3-methacryloyloxy-2-hydroxypropyl)-p-phenylenediamine, N,N'-bis(1-methylheptyl)-p-phenylenediamine, N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine, N,N'-bis(1-ethyl-3-methylpentyl)-p-phenylenediamine, and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine. Among these, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine is particularly preferred from the viewpoints of even higher antiaging effect and cost. The amount of the antiaging agent in the rubber composition may be 0.1 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the diene rubber contained in the rubber composition.

[0080] The type of softener is not particularly limited, but examples include mineral oil-based softeners derived from petroleum or coal tar, vegetable oil-based softeners derived from fatty oil or pine trees, and synthetic resin-based softeners.

[0081] The type of vulcanization accelerator is not particularly limited, but examples include thiazole-based accelerators such as mercaptobenzothiazole and di-2-benzothiazolyl disulfide, sulfenamide-based accelerators such as N-cyclohexyl-2-benzothiazolylsulfenamide, N,N'-dicyclohexyl-2-benzothiazolylsulfenamide, and N'-tert-butyl-2-benzothiazolylsulfenamide, and guanidine-based accelerators such as aminoguanidine and diphenylguanidine. These vulcanization accelerators may be used alone or in combination of two or more. The amount of vulcanization accelerator in the rubber composition is preferably 0.1 to 5 parts by mass per 100 parts by mass of diene rubber. The vulcanization accelerator aid is also not particularly limited, but examples include stearic acid and zinc oxide.

[0082] The type of vulcanizing agent is not particularly limited, but examples include sulfur and peroxide, and sulfur is preferred. The amount of vulcanizing agent in the rubber composition is preferably 0.1 to 5 parts by mass, and more preferably 0.5 to 3 parts by mass, per 100 parts by mass of diene rubber. When the amount of vulcanizing agent is 0.1 part by mass or more, more sufficient vulcanization is obtained, while when the amount is 5 parts by mass or less, the so-called scorch time does not shorten, and problems such as burning of the rubber during kneading can be more effectively suppressed.

[0083] The first rubber composition of the present embodiment may contain rubber other than the diene rubber described above, as long as it does not impede the solution of the problems of the present invention. Known rubbers may be used as such rubbers.

[0084] The first rubber composition of the present embodiment is produced, for example, by the following production method. However, the production method is not limited to this. That is, the production method includes a kneading and mixing step (A) of kneading or mixing a diene rubber, a compound (1), and a filler to obtain a rubber composition.

[0085] As the kneading and mixing means in the kneading and mixing step (A), a kneader is preferably used from the viewpoint of improving the interaction rate. Examples of such kneaders include a Laboplastomill, a Banbury mixer, an intensive mixer, an internal mixer, a roller, a kneader-ruder, a twin-screw extruder, and a mixing roll. There is no particular restriction on the order in which the components are added to the kneading and mixing means, but it is desirable to add the diene rubber first, followed by the other components. The method for adding the other components is not particularly limited, but examples include, when the components are powders, adding the powder as is, dissolving the components in a solvent and adding them as a solution, and adding them as an emulsion solution containing the components. For efficiency reasons, kneading and mixing in the kneading and mixing step (A) is preferably performed in one stage, but may be divided into multiple stages if necessary.

[0086] The temperature in the kneading and mixing step (A) is preferably 80° C. or higher and 180° C. or lower, and more preferably 100° C. or higher and 160° C. or lower. The kneading or mixing time in the kneading and mixing step (A) is preferably 30 seconds or higher and 600 seconds or lower, and more preferably 60 seconds or higher and 300 seconds or lower.

[0087] In the first method for producing a rubber composition of this embodiment, other conditions may be known, and for example, the production method may include a mastication step of kneading the diene rubber alone prior to the kneading and mixing step (A). Furthermore, compound (1) may be added in the mastication step.

[0088] (Composition containing modified diene rubber) Another example of the rubber composition of this embodiment (hereinafter referred to as the "second rubber composition") contains the above-mentioned modified diene rubber and a filler. The modified diene rubber is as described above, so a description thereof will be omitted here. The filler and optional components such as the silane coupling agent, various compounding agents, and diene rubber are the same as those in the first rubber composition, so a description thereof will be omitted here. Of the above, the diene rubber may contain a diene rubber before the modified diene rubber is modified. The second rubber composition may also contain the above-mentioned compound (1). Note that the amounts of these components in the second rubber composition are the same as those in the first rubber composition, except that instead of being based on 100 parts by mass of the diene rubber, they are based on a total of 100 parts by mass of the modified diene rubber and the diene rubber. Therefore, a description of preferred amounts thereof will be omitted.

[0089] The second rubber composition of the present embodiment may contain rubber other than the modified diene rubber described above, as long as it does not impede the solution of the problems of the present invention. Known rubbers may be used as such rubbers.

[0090] The second rubber composition of this embodiment is produced, for example, by the following production method. However, the production method is not limited to this. That is, the production method includes a kneading and mixing step (B) of kneading or mixing a diene rubber, compound (1), and a filler while heating to obtain a rubber composition. Alternatively, the production method includes a kneading and mixing step (C) of kneading the modified diene rubber obtained as described above with a filler to obtain a rubber composition.

[0091] The manufacturing method may further include a kneading step (D) of kneading or mixing the rubber composition, a vulcanizing agent, and a vulcanization accelerator to obtain an unvulcanized rubber composition. The manufacturing method may further include a vulcanization step of vulcanizing the unvulcanized rubber composition to obtain a vulcanized rubber composition.

[0092] The vulcanizing agent and vulcanization accelerator are preferably added to the kneading / mixing means in the kneading step (D), which can more reliably prevent scorching from occurring early. The antioxidant and softener that may be contained in the rubber composition are preferably added to the kneading / mixing means in the kneading / mixing step (B) or (C).

[0093] The kneading and mixing means in the kneading and mixing steps (B) and (C) may be the same as those in the kneading and mixing step (A), and therefore a description thereof will be omitted. There is no particular restriction on the order in which the components are added to the kneading and mixing means, but it is desirable to add the diene rubber or modified diene rubber first, followed by the other components. The method for adding the other components is not particularly limited, but examples include, when the components are powders, adding the powder as is, dissolving the components in a solvent and adding the components as a solution, and adding the components as an emulsion solution. For efficiency reasons, the kneading and mixing in the kneading and mixing steps (B) and (C) is preferably performed in a single stage, but may be divided into multiple stages as necessary.

[0094] The kneading temperature in the kneading mixing step (B) and the kneading step (C) is preferably 80°C or higher and 180°C or lower, and more preferably 100°C or higher and 160°C or lower. By adjusting the temperature within the above range, the diene rubber and compound (1) can be reacted more reliably, and when the rubber composition contains a silane coupling agent, the filler and the silane coupling agent can be interacted more effectively and reliably. From the same viewpoint, the kneading time in the kneading mixing step (B) and the kneading step (C) is preferably 30 seconds or higher and 600 seconds or lower, and more preferably 60 seconds or higher and 300 seconds or lower.

[0095] As the kneading means in the kneading step (D), the kneaders exemplified in the kneading and mixing step (B) can be used. The kneading temperature in the kneading step (D) is preferably 100°C or lower from the viewpoint of suppressing the progress of vulcanization.

[0096] In the second method for producing a rubber composition of this embodiment, other conditions may be known, and for example, the method may include a mastication step of kneading the diene rubber alone prior to the kneading and mixing step (B). Furthermore, compound (1) may be added in the mastication step.

[0097] The factors that enable this embodiment to solve the problem are believed to be as follows. However, the factors are not limited to these. In this embodiment, by using compound (1), compound (1) can easily react with the carbon-carbon double bond site in the main chain of the diene rubber to produce a modified diene rubber. This easy reactivity is believed to be due to the fact that compound (1) is a salt. When compound (1) reacts with the main chain of the diene rubber, the resulting modified diene rubber has many modifying groups derived from compound (1). The modifying groups have multiple nitrogen atoms in different rings that have a high affinity with fillers, which is thought to improve the dispersibility of the filler in the rubber composition. As a result, it is presumed that friction between fillers is suppressed, resulting in an excellent low heat buildup.

[0098] Compound (1) can be used as a dispersant for fillers, a heat-lowering agent, a heat-inhibiting material, and a heat-reducing agent, more specifically, as a dispersant for rubber, a heat-lowering agent for rubber, a heat-inhibiting material for rubber, or a heat-reducing agent for rubber. The rubber composition of this embodiment can also be used in, for example, tires, anti-vibration rubber, conveyor belts, and rubber parts thereof. Among these, using the rubber composition of this embodiment in tires is preferred because it improves the grip of the tire and also contributes to fuel economy. [Example]

[0099] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0100] Details of each component used in the following examples and comparative examples are shown below. Rubber component: 100 parts by weight, natural rubber, RSS#3 Vulcanization aid: 3 parts by mass, zinc oxide (zinc white), manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. : 2 parts by weight, stearic acid, Fujifilm Wako Pure Chemical Industries, Ltd. Antioxidant: 2 parts by mass, N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Carbon black: 10 parts by mass, manufactured by Asahi Carbon Co., Ltd., product name "Asahi #70" Silica: 50 parts by mass, BET surface area = 207 m 2 / g, manufactured by Tosoh Silica Corporation, product name "Nipsil AQ" Silane coupling agent: 4 parts by mass, bis(triethoxysilylpropyl) disulfide, manufactured by Evonik Japan Co., Ltd. Vulcanizing agent: 1.5 parts by mass, sulfur, average particle size 250 μm, manufactured by Hosoi Chemical Industry Co., Ltd. : 1 part by mass, 1,3-diphenylguanidine, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[0101] Example 1 (Synthesis of Compound (1a)) Compound (1a) of formula (1), in which R1 is a hydrogen atom, R2 is a hydrogen atom, R3 is an ethyl group, the bonding site of the triazine ring in the pyridine ring is the 4-position relative to the nitrogen atom in the pyridine ring, and X is a bromide ion, was synthesized as follows. A 100 mL single-neck flask was charged with 1.58 g (0.01 mol) of 4-cyanopyridine, 1.5 equivalents of bromoethane, and 10 mL of methyl ethyl ketone. A reflux condenser was attached and the mixture was heated and stirred at an external temperature of 80°C for 6 hours. The reaction mixture was cooled to room temperature, and 30 mL of isopropanol and 30 mL of diethyl ether were added to obtain a suspension. The suspension was filtered, washed with a small amount of chloroform, and then dried under reduced pressure to obtain 0.96 g of compound (1a) as a brown powder. The structural analysis by 1H-NMR revealed the following results. 1H-NMR(500MHz, CDCl3, δppm):9.80(d,J=6.5Hz,2H),9.47(d,J=2.0Hz,1H),9.19( d,J=6.5Hz,2H),8.97(d,J=2.5Hz,1H),5.26(q,J=7.5Hz,2H),1.83(t,J=7.5Hz,3H)

[0102] (Production of rubber composition) An unvulcanized rubber composition and a vulcanized rubber composition were prepared according to the following procedure. Mastication: Natural rubber was placed in a Banbury mixer (250 mL Labo Plastomill manufactured by Toyo Seiki Co., Ltd.; the same applies hereinafter) whose interior had been heated to 60°C, and kneaded at 60 rpm for 5 minutes. First kneading and mixing: The masticated rubber components were placed in a Banbury mixer heated to 70°C, and kneading was initiated at 100 rpm. After 30 seconds, the vulcanization aid, antioxidant, carbon black, and 0.5 parts by mass of compound (1a) were added. 30 seconds later, half of the silica was added, and 60 seconds later, the remaining half of the silica coated with a silane coupling agent was added. After that, the cylinder was opened for 1 minute when the rubber temperature reached 140°C. The cylinder was sealed again, and the mixture was kneaded until the rubber temperature reached 150°C, yielding a kneaded mixture. Second kneading and mixing: Using a 6-inch two-roll kneader (manufactured by Ikeda Kikai Kogyo), a vulcanizing agent and a vulcanization accelerator were added to the entire amount of the kneaded material obtained in the first kneading and mixing under conditions of a roll temperature of 30°C and a rotation speed of 25 rpm, and kneading was carried out to obtain an unvulcanized rubber composition. Press vulcanization: The unvulcanized rubber composition was vulcanized for 4.5 minutes at 160°C and 10 MPa using a hydraulic press (manufactured by Ohtake Machinery Co., Ltd.) to obtain a vulcanized rubber composition. The heat buildup of the obtained vulcanized rubber composition was evaluated as described below and found to be 90. The rubber reinforcing ability of the vulcanized rubber composition (affinity between rubber and filler) was also evaluated as described below and found to be 102.

[0103] The progress of the reaction between compound (1a) and diene rubber was confirmed as follows. Specifically, 60 parts by mass of isoprene rubber (manufactured by JSR, product name "IR2000"), 40 parts by mass of styrene-butadiene rubber (manufactured by Nippon Zeon, product name "NS166"), 1 part by mass of compound (1a), and 10 parts by mass of silica were kneaded for 10 minutes in a Banbury mixer at 140°C. Acetone-insoluble matter was extracted from the kneaded mixture by Soxhlet extraction using acetone. The extract was 1 Analysis by H-HMR confirmed that the peak of compound (1a) disappeared and a new peak appeared at 8-10 ppm, indicating that an inverse electron demand Aza-Diels-Alder reaction had occurred between compound (1a) and the double bond of the rubber.

[0104] Example 2 (Synthesis of compound (1b)) Compound (1b) of formula (1), in which R1 is a hydrogen atom, R2 is a hydrogen atom, R3 is an n-propyl group, the triazine ring is bonded to the pyridine ring at the 4-position relative to the nitrogen atom in the pyridine ring, and X is a bromide ion, was synthesized as follows. A 100 mL single-neck flask was charged with 1.58 g (0.01 mol) of 4-cyanopyridine, 3.0 equivalents of bromopropane, 3 mL of water, and 7 mL of methyl ethyl ketone. A reflux condenser was attached and the mixture was stirred at an external temperature of 80°C for 12 hours. The reaction mixture was cooled to room temperature, and 30 mL of isopropanol and 30 mL of diethyl ether were added to obtain a suspension. The suspension was filtered, washed with a small amount of chloroform, and then dried under reduced pressure to obtain 2.0 g of compound (1b) as a brown powder. The structure of the resulting powder was analyzed by 1H-NMR, and the results are shown below. 1H-NMR(500MHz,DMSO-d6,δppm):9.68(d,J=2.5Hz,1H),9.35(d,J=6.5Hz,2H),9.21(d,J=2.5Hz ,1H),9.01(d,J=6.5Hz,1H),4.72(q,J=7.5Hz,2H),2.02(tq,J=7.5Hz,2H),0.94(t,J=7.5Hz,3H)

[0105] (Production of rubber composition) A vulcanized rubber composition was obtained in the same manner as in Example 1, except that compound (1a) was replaced with compound (1b). The heat buildup of the obtained vulcanized rubber composition was evaluated as described below and found to be 87. The rubber reinforcing ability of the vulcanized rubber composition (affinity between rubber and filler) was also evaluated as described below and found to be 98.

[0106] Example 3 (Synthesis of compound (1c)) Compound (1c) represented by formula (1), in which R1 is a hydrogen atom, R2 is a hydrogen atom, R3 is an n-octyl group, the triazine ring is bonded to the pyridine ring at the 4-position relative to the nitrogen atom in the pyridine ring, and X is an iodide ion, was synthesized as follows. A 100 mL single-neck flask was charged with 1.58 g (0.01 mol) of 4-cyanopyridine, 1.2 equivalents of octane iodide, and 10 mL of methyl ethyl ketone. A reflux condenser was attached and the mixture was stirred at an external temperature of 100°C for 6 hours. The reaction mixture was cooled to room temperature, and 10 mL of isopropanol and 30 mL of diethyl ether were added to obtain a suspension. The suspension was filtered, washed with a small amount of chloroform, and then dried under reduced pressure to obtain 1.39 g of compound (1c) as a brown powder. The structure of the resulting powder was analyzed by 1H-NMR, and the results are shown below. 1H-NMR(500MHz, CDCl3, δppm):9.56(d,J=6.5Hz,2H),9.46(d,J=2.0Hz,1H),9.12(d,J=6.5Hz,2H),8.94( d,J=2.0Hz,1H),5.10(t,J=7.5Hz,2H),2.13(tq,J=7.5Hz,2H),1.58~1.24(m,10H),0.89(t,J=7.5Hz,3H)

[0107] (Production of rubber composition) A vulcanized rubber composition was obtained in the same manner as in Example 1, except that compound (1a) was changed to compound (1c). The heat buildup of the obtained vulcanized rubber composition was evaluated as described below and found to be 88. Furthermore, the rubber reinforcing ability of the vulcanized rubber composition (affinity between rubber and filler) was evaluated as described below and found to be 101.

[0108] Example 4 (Synthesis of compound (1d)) Compound (1d) represented by formula (1), in which R1 is a hydrogen atom, R2 is a hydrogen atom, R3 is a methyl group, the bonding site of the triazine ring in the pyridine ring is the 3-position relative to the nitrogen atom in the pyridine ring, and X is an iodide ion, was synthesized as follows. A 100 mL single-neck flask was charged with 1.58 g (0.01 mol) of 3-cyanopyridine, 1.2 equivalents of methyl iodide, and 10 mL of methyl ethyl ketone. A reflux condenser was attached and the mixture was stirred at an external temperature of 80°C for 4 hours to obtain a suspension. This suspension was filtered, washed with a small amount of chloroform, and then dried under reduced pressure to obtain 2.79 g of compound (1d) as a brown powder. The structure of the resulting powder was analyzed by 1H-NMR, and the results were as follows: 1H-NMR(500MHz,DMSO-d6,δppm):9.96(bs,1H),9.64(d,J=2.5Hz,1H),9.42(d,J=8.0Hz,1 H),9.21(d,J=6.0Hz,1H),9.16(d,J=2.5Hz,1H),8.36(dd,J=8.0,6.5Hz,1H),4.53(s,3H)

[0109] (Production of rubber composition) A vulcanized rubber composition was obtained in the same manner as in Example 1, except that compound (1a) was changed to compound (1d). The heat buildup of the obtained vulcanized rubber composition was evaluated as described below and found to be 91. Furthermore, the rubber reinforcing ability of the vulcanized rubber composition (affinity between rubber and filler) was evaluated as described below and found to be 104.

[0110] Example 5 (Synthesis of compound (1e)) Compound (1e) of formula (1), in which R1 is a hydrogen atom, R2 is a hydrogen atom, R3 is an ethoxycarbonylmethyl group (-CH2COOC2H5), the bonding site of the triazine ring in the pyridine ring is the 4-position relative to the nitrogen atom in the pyridine ring, and X is a chloride ion, was synthesized as follows. A 100 mL single-neck flask was charged with 1.58 g (0.01 mol) of 4-cyanopyridine, 1.5 equivalents of ethyl chloroacetate, 9 mL of toluene, and 1 mL of butanol. A reflux condenser was attached and the mixture was stirred at an external temperature of 110°C for 6 hours to obtain a suspension. This suspension was filtered, washed with a small amount of chloroform, and then dried under reduced pressure to obtain 1.34 g of the title compound (1e) as a brown powder. The structure of the obtained powder was analyzed by 1H-NMR, and the results are shown below. 1H-NMR(500MHz,DMSO-d6,δppm):9.69(d,J=2.5Hz,1H),9.41(d,J=6.5Hz,2H),9.23(d,J=2 .5Hz,1H),9.10(d,J=6.5Hz,2H),5.95(s,2H),4.28(q,J=7.0Hz,2H),1.29(t,J=7.0Hz,3H)

[0111] (Production of rubber composition) A vulcanized rubber composition was obtained in the same manner as in Example 1, except that compound (1a) was changed to compound (1e). The heat buildup of the obtained vulcanized rubber composition was evaluated as described below and found to be 89. Furthermore, the rubber reinforcing ability of the vulcanized rubber composition (affinity between rubber and filler) was evaluated as described below and found to be 107.

[0112] Example 6 (Synthesis of compound (1f)) Compound (1f) of formula (1), in which R1 is a hydrogen atom, R2 is a hydrogen atom, R3 is an acetamide group (-CH2CONH2), the binding site of the triazine ring in the pyridine ring is the 4-position relative to the nitrogen atom in the pyridine ring, and X is a chloride ion, was synthesized as follows. A 100 mL single-neck flask was charged with 1.58 g (0.01 mol) of 4-cyanopyridine, 1.5 equivalents of chloroacetic acid amide, 3 mL of water, and 7 mL of methyl ethyl ketone. A reflux condenser was attached and the mixture was stirred at an external temperature of 100°C for 6 hours. The reaction mixture was cooled to room temperature, and 100 mL of isopropanol and 20 mL of diethyl ether were added to obtain a suspension. The suspension was filtered, washed with a small amount of chloroform, and then dried under reduced pressure to obtain 2.47 g of compound (1f) as a brown powder. The structure of the obtained powder was analyzed by 1H-NMR, and the results are shown below. 1H-NMR(500MHz,DMSO-d6,δppm):9.67(d,J=2.5Hz,1H),9.24(d,J=6.0Hz,2H),9.2 1(d,J=2.5Hz,1H),9.02(d,J=7.0Hz,2H),8.28(bs,1H),7.77(bs,1H),5.61(s,2H)

[0113] (Production of rubber composition) A vulcanized rubber composition was obtained in the same manner as in Example 1, except that compound (1a) was replaced with compound (1f). The heat buildup of the obtained vulcanized rubber composition was evaluated as described below and found to be 85. The rubber reinforcing ability of the vulcanized rubber composition (affinity between rubber and filler) was also evaluated as described below and found to be 106.

[0114] Example 7 (Synthesis of compound (1g)) Compound (1g) represented by formula (1), in which R1 is a hydrogen atom, R2 is a hydrogen atom, R3 is an ethoxycarbonylmethyl group (-CH2COOC2H5), the bonding site of the triazine ring in the pyridine ring is the 3-position relative to the nitrogen atom in the pyridine ring, and X is a chloride ion, was synthesized as follows. A 100 mL single-neck flask was charged with 1.58 g (0.01 mol) of 3-cyanopyridine, 1.5 equivalents of ethyl chloroacetate, 9 mL of toluene, and 1 mL of acetonitrile. A reflux condenser was attached and the mixture was stirred at an external temperature of 100°C for 6 hours. The reaction mixture was cooled to room temperature, and 100 mL of isopropanol and 20 mL of diethyl ether were added to obtain a suspension. The suspension was filtered, washed with a small amount of chloroform, and then dried under reduced pressure to obtain compound (1g) as a brown powder (1.49 g). The structure of the obtained powder was analyzed by 1H-NMR, and the results were as follows: 1H-NMR(500MHz,D2O,δppm):9.82(bs,1H),9.51(d,8.0Hz,1H),9.39(d,2.5Hz,1H),9.00(m,2H),8.31(dd,8.0 Hz,6.0Hz,1H),5.67(s,2H),4.28(q,7.0Hz,2H),1.10(t,7.0Hz,3H)

[0115] (Production of rubber composition) A vulcanized rubber composition was obtained in the same manner as in Example 1, except that compound (1a) was changed to compound (1g). The heat buildup of the obtained vulcanized rubber composition was evaluated as described below and found to be 89. Furthermore, the rubber reinforcing ability of the vulcanized rubber composition (affinity between rubber and filler) was evaluated as described below and found to be 100.

[0116] Example 8 (Synthesis of compound (1h)) Compound (1h) represented by formula (1), in which R1 is a hydrogen atom, R2 is a hydrogen atom, R3 is a 2-butanol group (-CH2CH(OH)C2H5), the binding site of the triazine ring in the pyridine ring is the 3-position relative to the nitrogen atom in the pyridine ring, and X is an acetate ion, was synthesized as follows. A 100 mL single-neck flask was charged with 1.58 g (0.01 mol) of 3-cyanopyridine, 1.5 equivalents of butylene oxide, and 20 mL of acetic acid, and the mixture was stirred overnight at room temperature. The solvent was removed from the reaction mixture, washed with a small amount of diethyl ether, and then dried under reduced pressure to obtain compound (1h) as a brown oil (2.46 g). The structure of the resulting compound was analyzed by 1H-NMR, and the results are shown below. 1H-NMR(500MHz,D2O,δppm):(s,1H),9.51(d,8.5Hz,1H),9.47(d,2.0Hz,1H),9.09(d,2.0Hz,1H),9.06(d,6.0Hz,1H),8.33(d d,8.0,6.0Hz,1H),4.98(dd,13.5,3.0Hz,1H),4.59(dd,13.5,3.0Hz,1H),4.08(m,1H),1.88(s,3H),1.60(m,2H),0.90(m,3H)

[0117] (Production of rubber composition) A vulcanized rubber composition was obtained in the same manner as in Example 1, except that compound (1a) was changed to compound (1h). The heat buildup of the obtained vulcanized rubber composition was evaluated as described below and found to be 82. Furthermore, the rubber reinforcing ability of the vulcanized rubber composition (affinity between rubber and filler) was evaluated as described below and found to be 108.

[0118] Example 9 (Production of rubber composition) A vulcanized rubber composition was obtained in the same manner as in Example 6, except that compound (1f) was added in the mastication step before the first kneading and mixing. The heat buildup of the obtained vulcanized rubber composition was evaluated as described below and found to be 87. In addition, the rubber reinforcing ability of the vulcanized rubber composition (affinity between rubber and filler) was evaluated as described below and found to be 108.

[0119] (Comparative Example 1) (Production of rubber composition) A vulcanized rubber composition was obtained in the same manner as in Example 1, except that compound (1a) was not used. The heat buildup of the obtained vulcanized rubber composition was evaluated as described below, and was found to be 100. In addition, the rubber reinforcing ability of the vulcanized rubber composition (affinity between rubber and filler) was evaluated as described below, and was found to be 100.

[0120] (Comparative Example 2) (Production of rubber composition) A vulcanized rubber composition was obtained in the same manner as in Example 1, except that compound (1a) was changed to 3-(4-pyridyl)-1,2,4-triazine (hereinafter referred to as "compound (1i)"). The heat buildup of the obtained vulcanized rubber composition was evaluated as described below and found to be 100. In addition, the rubber reinforcing ability of the vulcanized rubber composition (affinity between rubber and filler) was evaluated as described below and found to be 91.

[0121] It was confirmed whether the reaction between compound (1i) and diene rubber had progressed in the same manner as in Example 1. As a result, it was confirmed that the peak of compound (1i) remained without disappearing, which indicated that the reaction between compound (1i) and rubber had not progressed.

[0122] (Comparative Example 3) A vulcanized rubber composition was obtained in the same manner as in Example 1, except that compound (1a) was replaced with 3,6-di(2-pyridyl)-1,2,4,5-tetrazine (hereinafter referred to as "compound (1j)"). The heat buildup of the obtained vulcanized rubber composition was evaluated as described below and found to be 98. The rubber reinforcing ability of the vulcanized rubber composition (affinity between rubber and filler) was also evaluated as described below and found to be 103.

[0123] It was confirmed whether the reaction between compound (1j) and diene rubber had progressed in the same manner as in Example 1. As a result, it was confirmed that the peak of compound (1j) had disappeared, which indicated that an inverse electron-demand Aza-Diels-Alder reaction had progressed between compound (1j) and the double bond of the rubber.

[0124] (Evaluation of heat generation) For each vulcanized rubber composition, loss tangent (tanδ) was measured at a temperature of 60°C, a dynamic strain of 0.5%, and a frequency of 10 Hz using a dynamic viscoelasticity measuring device (Seiko Instruments Inc., product name "DMS6100"). The loss tangent value for Comparative Example 1 was set to 100, and the results were evaluated as a relative value. A smaller value indicates a lower tanδ, and the rubber composition has low heat buildup.

[0125] (Evaluation of rubber reinforcement) For each vulcanized rubber composition, loss tangent (tanδ) was measured at the glass transition temperature of the vulcanized rubber composition using a dynamic viscoelasticity measuring device (Seiko Instruments Inc., product name "DMS6100"), with a dynamic strain of 0.5% and a frequency of 10 Hz. The loss tangent value for Comparative Example 1 was set at 100, and the results were evaluated as a relative value. A larger value indicates a higher tanδ, a higher affinity between the filler and the rubber in the rubber composition, and a higher rubber reinforcing property. [Industrial Applicability]

[0126] According to the present invention, it is possible to provide a compound that can be used as a filler dispersant, heat-lowering agent, heat-preventing agent, or heat-reducing agent, more specifically, a rubber dispersant, a rubber heat-lowering agent, a heat-preventing agent, or a heat-reducing agent for rubber. Furthermore, according to the present invention, it is possible to provide a rubber composition that can be used for tires, rubber vibration isolators, conveyor belts, and rubber parts thereof. Therefore, the compound has industrial applicability in these fields.

Claims

1. A compound represented by the following formula (2): 【Chemical 1】 (In formula (2), X represents an anion that forms a salt with pyridinium, and R 1 and R 2 each independently represents a hydrogen atom or a methyl group, R 4 represents a hydrogen atom, or an alkyl group, an aryl group, an aralkyl group, or an alkenyl group, which may have one or more groups selected from the group consisting of a hydroxy group, an alkoxy group, an acyl group, an amino group, an amido group, an epoxy group, a sulfanyl group, and an alkylsulfanyl group.

2. The R 1 and R 2 The compound according to claim 1 , wherein is a hydrogen atom.

3. A rubber composition comprising the compound according to claim 1 or 2, a diene rubber, and a filler.

4. 4. The rubber composition according to claim 3, wherein the diene rubber comprises at least one rubber selected from the group consisting of styrene-butadiene rubber, butadiene rubber, isoprene rubber, and natural rubber.

5. The rubber composition according to claim 3 or 4, wherein the filler comprises at least one selected from the group consisting of carbon black and silica.

6. The rubber composition according to any one of claims 3 to 5, further comprising a silane coupling agent.

7. The rubber composition according to any one of claims 3 to 6, further comprising sulfur and a vulcanization accelerator.

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