JP7627428B2 - Rubber composition and modified diene rubber - Google Patents

Description

The present invention relates to a rubber composition and a modified diene rubber.

Fillers are compounding agents that are mixed into rubber to reinforce it, 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 generation, i.e., low loss. Methods that use inorganic fillers are applied to rubber compositions for environmentally friendly, fuel-efficient tires, etc.

When an inorganic filler is compounded into a rubber composition, the inorganic filler, especially hydrophilic silica having silanol groups on its surface, has low affinity with hydrophobic rubber and is prone to agglomeration in the rubber composition. Therefore, in order to increase the reinforcing properties of the rubber by the inorganic filler and obtain low heat generation (low loss), it is necessary to increase the affinity between the inorganic filler and the rubber. As such a method, a method of imparting low heat generation to the rubber component using a specific tetrazine compound (see Patent Document 1) is known. As another method, a method of using a modified polymer obtained by reacting a modifier having a nitrone group and a carboxy group with a conjugated diene polymer not containing a 4-substituted olefin and/or a 3-substituted olefin together with a diene rubber (see Patent Document 2) is known.

International Publication No. 2017/057758 International Publication No. 2015/114845

However, it is expected that public interest in environmental issues such as atmospheric carbon dioxide concentrations and air pollution will continue to grow in the future, and there is a demand for technology that reduces tire rolling resistance and leads to improved fuel efficiency for automobiles. More specifically, there is a demand for technology that imparts even lower loss properties to rubber compositions that contain diene rubber and inorganic fillers such as silica, but such demands have not yet been fully met.

The present invention has been made in consideration of the above circumstances, and aims to provide a rubber composition and modified diene rubber with improved low heat generation properties.

As a result of intensive research conducted by the inventors to achieve the above object, they discovered that a specific rubber composition and modified diene rubber can improve low heat build-up, and thus completed the present invention.

（式（１）中、Ｘはピリジニウムと塩を形成するアニオンを示し、ＬはＣＲ₂又は窒素原子を示し、Ｒ₁及びＲ₂はそれぞれ独立に、水素原子、又は、置換基を有していてもよい、アルキル基、アリール基、アラルキル基、アルケニル基若しくは１価の複素環基を示し、Ｒ₃は、窒素原子、酸素原子及び硫黄原子からなる群より選ばれる１種以上を有していてもよい置換基を有していてもよい、アルキル基、アリール基、アラルキル基、又はアルケニル基を示す。）
［２］前記化合物は、下記式（２）で表される化合物である、上記ゴム組成物。

（式（２）中、Ｘはピリジニウムと塩を形成するアニオンを示し、ＬはＣＲ₂又は窒素原子を示し、Ｒ₁及びＲ₂はそれぞれ独立に、水素原子、又は、置換基を有していてもよい、アルキル基、アリール基、アラルキル基、アルケニル基若しくは１価の複素環基を示し、Ｒ₇は、水素原子、又は、ヒドロキシ基、アルコキシ基、アシル基、アミノ基、アミド基、エポキシ基、スルファニル基、及びアルキルスルファニル基からなる群より選ばれる１種以上を有していてもよい、アルキル基、アリール基、アラルキル基若しくはアルケニル基を示す。）
［３］前記化合物は、下記式（３）で表される化合物である、上記ゴム組成物。

（式（３）中、Ｘはピリジニウムと塩を形成するアニオンを示し、ＬはＣＲ₂又は窒素原子を示し、Ｒ₁及びＲ₂はそれぞれ独立に、水素原子、又は、置換基を有していてもよい、アルキル基、アリール基、アラルキル基、アルケニル基若しくは１価の複素環基を示し、Ｚは酸素原子、硫黄原子、アルキレン基又は－ＮＲ₆－で表される基を示し、Ｒ₅及びＲ₆はそれぞれ独立に、水素原子、又は、ヒドロキシ基、アルコキシ基、アシル基、アミノ基、アミド基、エポキシ基、スルファニル基、及びアルキルスルファニル基からなる群より選ばれる１種以上を有していてもよい、アルキル基、アリール基、アラルキル基、若しくはアルケニル基を示す。）
［４］前記Ｚが－ＮＲ₆－で表される基である、上記ゴム組成物。
［５］前記Ｒ₁及びＲ₂が水素原子である、上記ゴム組成物。
［６］前記ジエン系ゴムは、スチレンブタジエンゴム、ブタジエンゴム、イソプレンゴム及び天然ゴムからなる群より選ばれる１種以上を含む、上記ゴム組成物。
［７］前記充填材は、カーボンブラック及びシリカからなる群より選ばれる１種以上を含む、上記ゴム組成物。
［８］シランカップリング剤をさらに含む、上記ゴム組成物。
［９］硫黄と加硫促進剤とをさらに含む、上記ゴム組成物。
［１０］下記式（４ａ）、（４ｂ）、（４ｃ）、（４ｄ）、（４ｅ）、（４ｆ）、（４ｇ）、（４ｈ）、（４ｉ）、（４ｊ）又は（４ｋ）で表される変性基を有する変性ジエン系ゴム。

（各式中、Ｘはピリジニウムと塩を形成するアニオンを示し、ＬはＣＲ₂又は窒素原子を示し、Ｒ₁及びＲ₂はそれぞれ独立に、水素原子、又は置換基を有していてもよい、アルキル基、アリール基、アラルキル基、アルケニル基若しくは１価の複素環基を示し、Ｒ₃は、窒素原子、酸素原子及び硫黄原子からなる群より選ばれる１種以上を有していてもよい置換基を有していてもよい、アルキル基、アリール基、アラルキル基、又はアルケニル基を示し、Ｒはハロゲン原子又はアルキル基を示し、波線はジエン系ゴムの前記変性基との結合部位を示す。）
［１１］前記Ｒ₁及びＲ₂はそれぞれ独立に水素原子又はメチル基である、上記変性ジエン系ゴム。
［１２］上記変性ジエン系ゴムと、充填材と、を含むゴム組成物。 That is, the present invention is as follows.
[1] A rubber composition comprising a compound represented by the following formula (1), a diene rubber, and a filler:

(In formula (1), X represents an anion that forms a salt with pyridinium, L represents _CR2 or a nitrogen atom, _R1 and _R2 each independently represent a hydrogen atom, or an alkyl group, an aryl group, an aralkyl group, an alkenyl group, or a monovalent heterocyclic group which may have a substituent, and _R3 represents an alkyl group, an aryl group, an aralkyl group, or an alkenyl group which may have a substituent which may have one or more selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom.)
[2] The rubber composition according to the above, wherein the compound is a compound represented by the following formula (2):

(In formula (2), X represents an anion that forms a salt with pyridinium; L represents _CR2 or a nitrogen atom; _R1 and _R2 each independently represent a hydrogen atom, or an alkyl group, an aryl group, an aralkyl group, an alkenyl group, or a monovalent heterocyclic group which may have a substituent; and _R7 represents a hydrogen atom, or an alkyl group, an aryl group, an aralkyl group, or an 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 amido group, an epoxy group, a sulfanyl group, and an alkylsulfanyl group.)
[3] The rubber composition according to the above, wherein the compound is a compound represented by the following formula (3):

(In formula (3), X represents an anion that forms a salt with pyridinium; L represents _CR2 or a nitrogen atom; _R1 and _R2 each independently represent a hydrogen atom, or an alkyl group, aryl group, aralkyl group, alkenyl group or monovalent heterocyclic group which may have a substituent; 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 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 above rubber composition, wherein Z is a group represented by --NR ₆ --.
[5] The above rubber composition, wherein R ₁ and R ₂ are hydrogen atoms.
[6] 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.
[7] The above rubber composition, wherein the filler contains at least one selected from the group consisting of carbon black and silica.
[8] The above rubber composition, further comprising a silane coupling agent.
[9] The above rubber composition, further comprising sulfur and a vulcanization accelerator.
[10] 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):

(In each formula, X represents an anion that forms a salt with pyridinium, L represents _CR2 or a nitrogen atom, _R1 and _R2 each independently represent a hydrogen atom, or an alkyl group, an aryl group, an aralkyl group, an alkenyl group or a monovalent heterocyclic group which may have a substituent, _R3 represents an alkyl group, an aryl group, an aralkyl group or an alkenyl group which may have one or more substituents selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom, R represents a halogen atom or an alkyl group, and the wavy line represents a bonding site with the modifying group of the diene rubber.)
[11] The modified diene rubber as described above, wherein R ₁ and R ₂ each independently represent a hydrogen atom or a methyl group.
[12] A rubber composition comprising the modified diene rubber and a filler.

The present invention provides a rubber composition and modified diene rubber with improved low heat generation properties.

The following describes in detail an embodiment of the present invention (hereinafter, simply referred to as the "present embodiment"); however, the present invention is not limited to the present embodiment. The present invention can be modified in various ways without departing from the gist of the invention.

ここで、式（１）中、Ｘはピリジニウムと塩を形成するアニオンを示し、ＬはＣＲ₂又は窒素原子を示し、Ｒ₁及びＲ₂はそれぞれ独立に、水素原子、又は、置換基を有していてもよい、アルキル基、アリール基、アラルキル基、アルケニル基若しくは１価の複素環基を示し、Ｒ₃は、窒素原子、酸素原子及び硫黄原子からなる群より選ばれる１種以上を有していてもよい置換基を有していてもよい、アルキル基、アリール基、アラルキル基、又はアルケニル基を示す。本発明による作用効果より有効かつ確実に奏する観点から、Ｒ₁及びＲ₂は、それぞれ独立に、水素原子又はアルキル基であると好ましく、水素原子又はメチル基であるとより好ましく、水素原子であると更に好ましい。同様の観点から、Ｒ₃は、アルキル基であると好ましく、メチル基であるとより好ましい。 (Rubber composition containing compound represented by formula (1))
An example of the rubber composition of this embodiment (hereinafter referred to as the “first rubber composition”) contains a compound represented by the following formula (1) (hereinafter also referred to as “compound (1)”), a diene rubber, and a filler.

Here, in formula (1), X represents an anion that forms a salt with pyridinium, L represents _CR2 or a nitrogen atom, _R1 and _R2 each independently represent a hydrogen atom, or an alkyl group, an aryl group, an aralkyl group, an alkenyl group, or a monovalent heterocyclic group that may have a substituent, and _R3 represents an alkyl group, an aryl group, an aralkyl group, or an alkenyl group that may have one or more substituents selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom. From the viewpoint of more effectively and reliably achieving the effects of the present invention, _R1 and _R2 each independently represent a hydrogen atom or an alkyl group, more preferably a hydrogen atom or a methyl group, and even more preferably a hydrogen atom. From the same viewpoint, _R3 is preferably an alkyl group, and more preferably a methyl group.

From the viewpoint of more effectively and reliably achieving the effects of the present invention, the alkyl groups in R ₁ and R ₂ are preferably alkyl groups having 1 to 18 carbon atoms, and more preferably alkyl groups having 1 to 10 carbon atoms. Examples of such alkyl groups include linear or branched alkyl groups having 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and cyclic alkyl groups having 3 to 10 carbon atoms, more preferably 3 to 8 carbon atoms, and even more preferably 3 to 6 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 groups; and cyclic alkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. Among these, even more preferred alkyl groups are linear or branched alkyl groups having 1 to 6 carbon atoms, particularly preferred are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and n-pentyl groups, extremely preferred are methyl and ethyl groups, and most preferred is methyl group.

From the viewpoint of more effectively and reliably achieving the effects of the present invention, the aryl group in _R1 and _R2 is preferably an aryl group having 6 to 14 carbon atoms. 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 preferable, and a phenyl group is even more preferable. Phenyl groups having a substituent are also preferable.

From the viewpoint of more effectively and reliably achieving the effects of the present invention, the aralkyl group in _R1 and _R2 is preferably an aralkyl group having 7 to 20 carbon atoms. 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 preferable, and a benzyl group is even more preferable.

From the viewpoint of more effectively and reliably achieving the effects of the present invention, the alkenyl group in R ₁ and R ₂ is preferably an alkenyl group having 2 to 18 carbon atoms. Examples of such alkenyl groups include alkenyl groups having 2 to 6 carbon atoms, and specific examples thereof include a vinyl group, a 1-propenyl group, an allyl group, an isopropenyl group, a 1-butenyl group, and a 2-butenyl group.

From the viewpoint of more effectively and reliably exerting the effects of the present invention, the monovalent heterocyclic group for _R1 and _R2 preferably has 4 to 14 atoms constituting the heterocycle (number of ring members), and more preferably has 5 to 10 atoms. 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, a 2-quinolyl group, a 3-quinolyl group, a 4-quinolyl group, a 5-quinolyl group, a 6-quinolyl group, a 7-quinolyl group, an 8-quinolyl group, a 1-isoquinolyl group, a quinolyl 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, a quinolyl group, a 7-phthalazyl group, a 8-phthalazyl group, a 1-tetrahydroquinolyl group, a 2-tetrahydroquinolyl group, a 3-tetrahydroquinolyl group, a 4-tetrahydroquinolyl group, a 5-tetrahydroquinolyl group, a 6-tetrahydroquinolyl group, a 7-tetrahydroquinolyl group, a 8-tetrahydroquinolyl group, a 1-pyrrolyl group, a 2-pyrrolyl group, a 3-pyrrolyl group, a 2-furyl group, a 3-furyl group, a 2-thienyl group, a 3-thienyl group, a 1-imidazolyl group, a 2-imidazolyl group, a 4-imidazolyl group, a 5-imidazolyl group, a 1-pyrazolyl group, a 3-pyrazolyl group, a 4-pyrazolyl group, a 5-pyrazolyl group, a 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, a 2-benzofuranyl group, a 3-isoindolyl group, a 4-isoindolyl group, a 5-isoindolyl group, a 6-isoindolyl group, a 7-isoindolyl group, a 1-benzimidazolyl group, a 2-benzimidazolyl group, a 4-benzimidazolyl group, a 5-benzimidazolyl group, a 6-benzimidazolyl group, a 7-benzimidazolyl group, a 2-benzofuranyl group, a 3-benzofuranyl group, a 4-benzofuranyl group, a 5-benzofuranyl group, a 6-benzofuranyl group, a 7-benzofuranyl group, a 1-isobenzofuranyl group, a 3-isobenzofuranyl group, a 4-isobenzofuranyl group, a 5-isobenzofuranyl group, a 6-isobenzofuranyl group, a 7-benzofuranyl group, a 2-benzothienyl group, a 7-isobenzophenyl group, a 2-benzothienyl group, a 3-benzothienyl group, a 4-benzothienyl group, a 5-benzothienyl group, a 6-benzothienyl group, a 7-benzothienyl group, a 2-benzoxazolyl group, a 4-benzoxazolyl group, a 5-benzoxazolyl group, a 6-benzoxazolyl group, a 7-benzoxazolyl group, a 2-benzothiazolyl group, a 4-benzothiazolyl group, a 5-benzothiazolyl group, a 6-benzothiazolyl group, a 7-benzothiazolyl group, a 1-indazolyl group, a 3-indazolyl group, a 4-indazolyl group, a 5-indazolyl group, a 6-indazolyl group, a 7-indazolyl group, Examples of the aryl group include a 2-morpholyl group, a 3-morpholyl group, a 4-morpholyl group, a 1-piperazyl group, a 2-piperazyl group, a 1-piperidyl group, a 2-piperidyl group, a 3-piperidyl group, a 4-piperidyl group, a 2-tetrahydropyranyl group, a 3-tetrahydropyranyl group, a 4-tetrahydropyranyl group, a 2-tetrahydrothiopyranyl group, a 3-tetrahydrothiopyranyl group, a 4-tetrahydrothiopyranyl group, a 1-pyrrolidyl group, a 2-pyrrolidyl group, a 3-pyrrolidyl group, a 2-tetrahydrofuranyl group, a 3-tetrahydrofuranyl group, a 2-tetrahydrothienyl group, and a 3-tetrahydrothienyl group. Among these, a pyridyl group, a furanyl group, a thienyl group, a pyrimidyl group, and a pyrazyl group are more preferred, and a pyridyl group is particularly preferred.

Examples of the substituents in R ₁ and R ₂ include a halogen atom, an amino group, an aminoalkyl group, an alkoxycarbonyl group, an acyl group, an acyloxy group, an amide 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 sulfanyl group, an alkylsulfanyl group, and an arylsulfanyl group. The number of the substituents in each of R ₁ and R ₂ may be preferably 1 to 5, and more preferably 1 to 3.

Halogen atoms that are substituents include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

The amino group as a substituent includes not only the 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 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 dimethylamino group, ethylmethylamino group, and diethylamino group.

Examples of the aminoalkyl group that is 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.

Examples of the alkoxycarbonyl group that is a substituent include alkoxycarbonyl groups with an alkoxy carbon number of 1 to 4, such as methoxycarbonyl and ethoxycarbonyl groups.

Examples of the acyl group that is 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.

Examples of the acyloxy group that is a substituent include an alkylcarbonyloxy group having an alkyl carbon number of 1 to 4, such as an acetyloxy group, a propionyloxy group, and an n-butyryloxy group.

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

Examples of the carboxyalkyl group that is a substituent include carboxy-alkyl groups having an alkyl carbon number of 1 to 6, 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.

Examples of the hydroxyalkyl group that is 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.

Examples of the alkoxy group that is a substituent include linear, branched, or 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; 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.

Examples of aryloxy groups that are substituents include aryloxy groups having 6 to 14 carbon atoms, such as phenoxy, biphenyloxy, and naphthoxy groups.

The alkylsulfanyl group as the substituent may be, for example, the above-mentioned alkoxy group in which the oxygen atom is replaced with a sulfur atom. The arylsulfanyl group as the substituent may be, for example, the above-mentioned aryloxy group in which the oxygen atom is replaced with a sulfur atom. The alkyl group, aryl group, and monovalent heterocyclic group as the substituent are exemplified as those in _R1 and _R2 , and the explanation here is omitted.

Preferred embodiments and examples of the alkyl group, aryl group, aralkyl group, and alkenyl group in _R3 are the same as those in _R1 and _R2 , and the explanation here is omitted. In addition, the substituent in _R3 which may have one or more selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom may be any of the substituents in _R1 and _R2 which have one or more selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom.

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; alkyl sulfate ions having 1 to 4 carbon atoms 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 exerting the effects of the present invention, halide ions and organic acid ions are preferred, and chloride ions, bromide ions, iodide ions, and acetate ions are more preferred.

ここで、式（２）中、Ｘはピリジニウムと塩を形成するアニオンを示し、ＬはＣＲ₂又は窒素原子を示し、Ｒ₁及びＲ₂はそれぞれ独立に、水素原子、又は、置換基を有していてもよい、アルキル基、アリール基、アラルキル基、アルケニル基若しくは１価の複素環基を示し、Ｒ₇は、水素原子、又は、ヒドロキシ基、アルコキシ基、アシル基、アミノ基、アミド基、エポキシ基、スルファニル基、及びアルキルスルファニル基からなる群より選ばれる１種以上を有していてもよい、アルキル基、アリール基、アラルキル基若しくはアルケニル基を示す。本発明による作用効果をより有効かつ確実に奏する観点から、ＬはＣＲ₂であると好ましく、Ｒ₇は、－ＣＨ（ＯＨ）Ｒ₄であると好ましい。ここで、Ｒ₄は、水素原子、又は、ヒドロキシ基、アルコキシ基、アシル基、アミノ基、アミド基、エポキシ基、スルファニル基、及びアルキルスルファニル基からなる群より選ばれる１種以上を有していてもよい、アルキル基、アリール基、アラルキル基若しくはアルケニル基を示す。 From the viewpoint of more effectively and reliably exerting the effects of the present invention, the compound (1) according to this embodiment is preferably a compound represented by the following formula (2).

In the formula (2), X represents an anion that forms a salt with pyridinium, L represents _CR2 or a nitrogen atom, _R1 and _R2 each independently represent a hydrogen atom, or an alkyl group, an aryl group, an aralkyl group, an alkenyl group, or a monovalent heterocyclic group which may have a substituent, and _R7 represents a hydrogen atom, or an alkyl group, an aryl group, an aralkyl group, or an 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. From the viewpoint of more effectively and reliably exerting the effects of the present invention, L is preferably _CR2 , and _R7 is preferably -CH(OH) _R4 . Here, _R4 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.

X, L, R ₁ and R ₂ 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 the explanation here is omitted.

Preferred aspects and examples of the alkyl group, aryl group, aralkyl group, and alkenyl group in R ₇ , as well as the alkoxy group, acyl group, amino group, amide group, and alkylsulfanyl group, which are the substituents thereof, are the same as those in R ₁ and R ₂ , and the description here is omitted. However, when R ₃ in the above formula (1) has -CH ₂ -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), R ₇ differs from R ₃ in that it does not have this group. Furthermore, preferred aspects and examples of the alkyl group, aryl group, aralkyl group, and alkenyl group in R ₄ , as well as the alkoxy group, acyl group, amino group, amide group, and alkylsulfanyl group, which are the substituents thereof, are the same as those in R ₃ , and the description here is omitted. However, when R ₇ has -C(H)OH- bonded to the above methylene group, R ₄ differs from R ₇ in that it does not have this group.

ここで、式（３）中、Ｘはピリジニウムと塩を形成するアニオンを示し、ＬはＣＲ₂又は窒素原子を示し、Ｒ₁及びＲ₂はそれぞれ独立に、水素原子、又は、置換基を有していてもよい、アルキル基、アリール基、アラルキル基、アルケニル基若しくは１価の複素環基を示す。Ｚは酸素原子、硫黄原子、アルキレン基又は－ＮＲ₆－で表される基を示し、アルキレン基の炭素数は、例えば１～１０である。Ｒ₅及びＲ₆は、それぞれ独立に、水素原子、又は、ヒドロキシ基、アルコキシ基、アシル基、アミノ基、アミド基、エポキシ基、スルファニル基、及びアルキルスルファニル基からなる群より選ばれる１種以上を有していてもよい、アルキル基、アリール基、アラルキル基、若しくはアルケニル基を示し、本発明による作用効果をより有効かつ確実に奏する観点から水素原子であると好ましい。本発明による作用効果をより有効かつ確実に奏する観点から、ＬはＣＲ₂であると好ましい。 From the viewpoint of more effectively and reliably exerting the effects of the present invention, compound (1) according to this embodiment is more preferably a compound represented by the following formula (3).

Here, in formula (3), X represents an anion that forms a salt with pyridinium, L represents _CR2 or a nitrogen atom, and _R1 and _R2 each independently represent a hydrogen atom, or an alkyl group, an aryl group, an aralkyl group, an alkenyl group, or a monovalent heterocyclic group which may have a substituent. Z represents an oxygen atom, a sulfur atom, an alkylene group, or a group represented by _-NR6- , and the number of carbon atoms of the alkylene group is, for example, 1 to 10. _R5 and _R6 each independently represent a hydrogen atom, or an alkyl group, an aryl group, an aralkyl group, or an 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, and are preferably hydrogen atoms from the viewpoint of more effectively and reliably achieving the effects of the present invention. From the viewpoint of more effectively and reliably achieving the effects of the present invention, L is preferably _CR2 .

X, L, R ₁ and R ₂ 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 the explanation here is omitted.

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 which are the substituents thereof, are the same as those in _R1 and _R2 , and therefore the explanation here is omitted. 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-.

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.

Compound (1) according to this embodiment may be synthesized by a conventional method, or may be synthesized according to the method described in the Examples or a method conforming thereto.

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 diene rubber.

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

The inorganic filler contains at least one type of solid particle selected from the group consisting of silicon, oxides or hydroxides of main group metals or transition metals, and hydrates thereof, and carbonates of these metals. Examples of inorganic fillers include silica; alumina (Al ₂ O ₃ ) such as γ-alumina and α-alumina; alumina monohydrate (Al ₂ O ₃ .H ₂ O) such as boehmite and diaspore; aluminum hydroxide [Al(OH) ₃ ] such as gibbsite and bayerite; aluminum carbonate [Al ₂ (CO ₃ ) ₂ ], magnesium hydroxide [Mg(OH) ₂ ], magnesium oxide (MgO), magnesium carbonate (MgCO ₃ ), talc (3MgO.4SiO ₂ .H ₂ O), attapulgite (5MgO.8SiO ₂ .9H ₂ O), titanium white (TiO ₂ ), titanium black (TiO _2n-1 ), calcium oxide (CaO), calcium hydroxide [Ca(OH) ₂ ], magnesium aluminum oxide (MgO.Al ₂ O ₃ ), clay (Al ₂ O _3.2SiO2 ), kaolin ( _{Al2O3.2SiO2.2H2O} ) _{, pyrophyllite ( Al2O3.4SiO2.H2O ) , bentonite} ( _{Al2O3.4SiO2.2H2O )} , _{aluminum silicate ( clay} ; e.g. Al2SiO5, _{Al4.3SiO4.5H2O} ) _{, magnesium} silicate (talc; e.g. _Mg2SiO4 , MgSiO3), calcium silicate (e.g. _Ca2.SiO4 ), calcium aluminum silicate (e.g. _{Al2O3.CaO.2SiO2} ), calcium magnesium silicate _{( CaMgSiO4 )} , _calcium carbonate ( _CaCO3 ), _zirconium oxide ( _ZrO2 ), zirconium _hydroxide [ZrO _{( OH} ) _{2.nH2O ]} O], zirconium carbonate [Zr( _CO3 ) ₂ ], zinc acrylate, zinc methacrylate, and crystalline aluminosilicates containing hydrogen, alkali metals or alkaline earth metals to correct the charge, such as various zeolites. These inorganic fillers may have their surfaces organically treated in order to improve their affinity with diene rubber.

Among the above fillers, it is preferable that the inorganic filler 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 from the same viewpoint as above, wet silica is more preferable. The silica may have its surface organically treated to improve its affinity with diene rubber.

The BET specific surface area of the silica is not particularly limited, and is preferably, for example, 40 m ² /g or more and 350 m ² /g or less. By having the BET specific surface area within the above numerical range, both the rubber reinforcing effect 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 more preferably 80 to 300 m ² /g, even more preferably 100 m ² /g or more and 270 m ² /g or less, and even more preferably 110 m ² /g or more and 270 m ² /g or less. The BET specific surface area is measured in accordance with ISO5794/1.

Examples of commercially available products of such silica include products manufactured by Quechen Silicon Chemical Co., Ltd. under the trade names "HD165MP" (BET specific surface area = 165 ^m2 /g), "HD115MP" (BET specific surface area = 115 ^m2 /g), "HD200MP" (BET specific surface area = 200 ^m2 /g), and "HD250MP" (BET specific surface area = 250 ^m2 /g), products manufactured by Tosoh Silica Corporation under the trade names "Nipsil AQ" (BET specific surface area = 205 ^m2 /g) and "Nipsil KQ" (BET specific surface area = 240 ^m2 /g), and product name "Ultrasil VN3" (BET specific surface area = 175 ^m2 /g) manufactured by Degussa.

By including an inorganic filler, preferably silica, in the first rubber composition together with compound (1), the dispersibility of the inorganic filler is significantly improved, and the low heat generation property of the rubber composition can be further improved.

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 it may be, for example, a commercially available carbon black.

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 these, it is preferred that the carbon black comprises SAF, ISAF, IISAF, N134, N234, N330, N339, N375, HAF or FEF grade carbon black.

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 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, by using compound (1) in particular, even if the amount of filler is increased more than before, the filler coagulant can be suppressed, so that the low heat generation property and the rubber reinforcement can be further improved.

The first rubber composition of this embodiment preferably contains a silane coupling agent in order to further enhance the bonding between the filler and the diene rubber.

Silane coupling agents include, but are not limited to, 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) pyl) trisulfide, 3-hexanoylthiopropyl triethoxysilane, 3-octanoylthiopropyl triethoxysilane, 3-decanoylthiopropyl triethoxysilane, 3-lauroylthiopropyl triethoxysilane, 2-hexanoylthioethyl triethoxysilane, 2-octanoylthioethyl triethoxysilane, 2-decanoylthioethyl triethoxysilane, 2-lauroylthioethyl triethoxysilane, 3-hexanoylthiopropyl trimeth xysilane, 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-dimethylthiocarbamoyltetrasulfide, 3-trimethoxysilylpropylbenzothiazolyltetrasulfide, and 3-trimethoxysilylpropylmethacryloylmonosulfide.

When the rubber composition contains a silane coupling agent, the amount of the silane coupling agent is preferably 1 to 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.

The first rubber composition of this embodiment may contain compounding agents commonly used in the rubber industry, such as anti-aging agents, softening agents, vulcanization accelerators, vulcanization accelerator assistants, vulcanizing agents, etc., appropriately selected within a range that does not impair the purpose of this embodiment. Among these, it is preferable for the first rubber composition to contain a vulcanization accelerator and a vulcanizing agent, and it is more preferable for the first rubber composition to contain a vulcanization accelerator and sulfur, which is a type of vulcanizing agent. Commercially available products can be used as these compounding agents.

The type of anti-aging agent is not particularly limited, but examples thereof include naphthylamines, p-phenylenediamines, hydroquinone derivatives, bis, tris, polyphenols, diphenylamines, quinolines, monophenols, thiobisphenols, and hindered phenols. Among these, p-phenylenediamines and diphenylamines are preferred from the viewpoint of further anti-aging effect. Examples of diphenylamine anti-aging agents include 4,4'-(α-methylbenzyl)diphenylamine, 4,4'-(α,α-dimethylbenzyl)diphenylamine, p-(p-toluene-sulfonylamide)diphenylamine, and 4,4'-dioctyldiphenylamine. Among these, 4,4'-(α-methylbenzyl)diphenylamine is particularly preferred from the viewpoint of further anti-aging effect. Furthermore, examples of the 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 viewpoint of even higher anti-aging effect and cost. The amount of the anti-aging 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.

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 oils or pine trees, and synthetic resin-based softeners.

The type of vulcanization accelerator is not particularly limited, but examples thereof 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 are used alone or in combination of two or more. The amount of the vulcanization accelerator in the rubber composition is preferably 0.1 parts by mass or more and 5 parts by mass or less per 100 parts by mass of diene rubber. In addition, examples of the vulcanization accelerator aid include, but are not particularly limited to, stearic acid and zinc oxide.

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. If the amount of vulcanizing agent is 0.1 parts by mass or more, more sufficient vulcanization can be obtained, and if it is 5 parts by mass or less, the so-called scorch time does not shorten, and problems such as the rubber burning during kneading can be more effectively suppressed.

The first rubber composition of this embodiment may contain rubber other than the diene rubber described above, as long as it does not impede the problem-solving of the present invention. Any known rubber may be used as such a rubber.

The first 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 has a kneading and mixing step (A) in which a diene rubber, a compound (1), and a filler are kneaded or mixed to obtain a rubber composition.

As the kneading and mixing means in the kneading and mixing step (A), it is preferable to use a kneader from the viewpoint of improving the interaction rate. Examples of such kneading machines include a lab plastomill, 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 each component is added to the kneading and mixing means, but it is preferable to add the diene rubber first and then the other components. The method of adding the other components is not particularly limited, but for example, when the component is a powder, the powder can be added as it is, the component can be dissolved in a solvent and added as a solution, and the component can be added as an emulsion solution. In addition, the kneading and mixing in the kneading and mixing step (A) is preferably performed in one stage for efficiency, but may be divided into multiple stages as necessary.

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.

In the first rubber composition manufacturing method of this embodiment, the other conditions may be known. For example, the manufacturing method may include a mastication step in which the diene rubber is kneaded alone prior to the kneading and mixing step (A). Furthermore, compound (1) may be added in the mastication step.

ここで、各式中、Ｘはピリジニウムと塩を形成するアニオンを示し、ＬはＣＲ₂又は窒素原子を示し、Ｒ₁及びＲ₂はそれぞれ独立に、水素原子、又は置換基を有していてもよい、アルキル基、アリール基、アラルキル基、アルケニル基若しくは１価の複素環基を示し、Ｒ₃は、窒素原子、酸素原子及び硫黄原子からなる群より選ばれる１種以上を有していてもよい置換基を有していてもよい、アルキル基、アリール基、アラルキル基、又はアルケニル基を示し、Ｒはハロゲン原子又はアルキル基を示し、波線はジエン系ゴムの上記変性基との結合部位を示す。 (Modified diene rubber)
The modified diene rubber of the present 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)").

In each formula, X represents an anion that forms a salt with pyridinium, L represents _CR2 or a nitrogen atom, _R1 and _R2 each independently represent a hydrogen atom, or an alkyl group, an aryl group, an aralkyl group, an alkenyl group or a monovalent heterocyclic group which may have a substituent, R3 represents an alkyl group, an aryl group, an aralkyl group or an alkenyl group which may have one or more substituents selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom, _R represents a halogen atom or an alkyl group, and the wavy line represents a bonding site with the above-mentioned modifying group of the diene rubber.

X, L, R ₁ , R ₂ and R ₃ 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 the explanation here is omitted.

The preferred embodiments and examples of the alkyl group in R are the same as those in _R1 and _R2 , and therefore the explanation thereof will be omitted here.

The modified diene rubber having modifying groups (4a) to (4k) can be obtained by carrying out an inverse electron demand Aza-Diels-Alder reaction between compound (1) and a double bond in the diene rubber.

ここで、各式中のＸ、Ｌ、Ｒ₁、Ｒ₂及びＲ₃は、上記式（１）におけるものと同義であり、上記式（１）におけるものと同じ例示及び好ましい態様であるので、ここでの説明は省略する。 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)>

Here, X, L, _R1 , _R2 and _R3 in each formula are the same as those in the above formula (1), and are the same examples and preferred embodiments as those in the above formula (1), so the explanation here is omitted.

ここで、各式中のＸ、Ｌ、Ｒ₁、Ｒ₂及びＲ₃は、上記式（１）におけるものと同義であり、上記式（１）におけるものと同じ例示及び好ましい態様であるので、ここでの説明は省略する。 In the above scheme (7), a bicyclo ring structure represented by formula (1B) is formed by an inverse electron demand Aza-Diels-Alder reaction between the double bond site of the diene rubber represented by formula (1A) and the compound (1). The -N=N- portion 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)>

Here, X, L, _R1 , _R2 and _R3 in each formula are the same as those in the above formula (1), and are the same examples and preferred embodiments as those in the above formula (1), so the explanation here is omitted.

ここで、各式中のＸ、Ｌ、Ｒ₁、Ｒ₂及びＲ₃は、上記式（１）におけるものと同義であり、上記式（１）におけるものと同じ例示及び好ましい態様であるので、ここでの説明は省略する。また、各式中のＲにおけるアルキル基の好ましい態様及び例示されるものは、Ｒ₃におけるものと同様であり、ここでの説明は省略する。 In the above scheme (8), similarly to the 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 the compound (1), and then a modified diene rubber having a structure represented by formula (4b) or (4c) is produced.
<Scheme 9>

Here, X, L, _R1 , _R2 and _R3 in each formula are the same as those in the above formula (1), and are the same examples and preferred embodiments as those in the above formula (1), so the explanation here is omitted. In addition, the preferred embodiments and exemplified alkyl groups in R in each formula are the same as those in _R3 , so the explanation here is omitted.

ここで、各式中のＸ、Ｌ、Ｒ₁、Ｒ₂及びＲ₃は、上記式（１）におけるものと同義であり、上記式（１）におけるものと同じ例示及び好ましい態様であるので、ここでの説明は省略する。また、各式中のＲにおけるアルキル基の好ましい態様及び例示されるものは、Ｒ₃におけるものと同様であり、ここでの説明は省略する。 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), and then a modified diene rubber having a structure represented by formula (4d), (4e), (4f) or (4g) is produced by denitrification. When R at the double bond site of the diene rubber represented by formula (1G) is a halogen atom, the halogen atom may be eliminated, and in that case, a modified diene rubber having a structure represented by formula (4a) is produced by an oxidation reaction.
<Scheme 10>

Here, X, L, _R1 , _R2 and _R3 in each formula are the same as those in the above formula (1), and are the same examples and preferred embodiments as those in the above formula (1), so the explanation here is omitted. In addition, the preferred embodiments and exemplified alkyl groups in R in each formula are the same as those in _R3 , so the explanation here is omitted.

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. When R at the double bond site of the diene rubber represented by formula (1I) is a halogen atom, the halogen atom may be eliminated, and in that case, a modified diene rubber having a structure represented by formula (4a) is produced by an oxidation reaction.

ここで、各式中、Ｘはピリジニウムと塩を形成するアニオンを示し、ＬはＣＲ₂又は窒素原子を示し、Ｒ₁及びＲ₂はそれぞれ独立に、水素原子、又は置換基を有していてもよい、アルキル基、アリール基、アラルキル基、アルケニル基若しくは１価の複素環基を示し、Ｒ₇は、水素原子、又は、ヒドロキシ基、アルコキシ基、アシル基、アミノ基、アミド基、エポキシ基、スルファニル基、及びアルキルスルファニル基からなる群より選ばれる１種以上を有していてもよい、アルキル基、アリール基、アラルキル基若しくはアルケニル基を示し、Ｒはハロゲン原子又はアルキル基を示し、波線はジエン系ゴムの上記変性基との結合部位を示す。 From the viewpoint of more effectively and reliably exerting 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).

In each formula, X represents an anion that forms a salt with pyridinium, L represents _CR2 or a nitrogen atom, _R1 and _R2 each independently represent a hydrogen atom, or an alkyl group, an aryl group, an aralkyl group, an alkenyl group, or a monovalent heterocyclic group which may have a substituent, _R7 represents a hydrogen atom, or an alkyl group, an aryl group, an aralkyl group, or an alkenyl group which may have one or more selected from the group consisting of a hydroxyl 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 a bonding site with the above-mentioned modifying group of the diene rubber.

X, L, R ₁ , R ₂ and R ₇ have the same meanings as those in the above formula (2), and are the same examples and preferred embodiments as those in the above formula (2), so the explanation here is omitted.

The preferred embodiments and examples of the alkyl group in R are the same as those in _R1 and _R2 , and therefore the explanation thereof will be omitted here.

ここで、各式中、Ｘはピリジニウムと塩を形成するアニオンを示し、ＬはＣＲ₂又は窒素原子を示し、Ｒ₁及びＲ₂はそれぞれ独立に、水素原子、又は置換基を有していてもよい、アルキル基、アリール基、アラルキル基、アルケニル基若しくは１価の複素環基を示し、Ｚは酸素原子、硫黄原子、アルキレン基又は－ＮＲ₆－で表される基を示し、Ｒ₅及びＲ₆は、それぞれ独立には、水素原子、又は、ヒドロキシ基、アルコキシ基、アシル基、アミノ基、アミド基、エポキシ基、スルファニル基、及びアルキルスルファニル基からなる群より選ばれる１種以上を有していてもよい、アルキル基、アリール基、アラルキル基、若しくはアルケニル基を示し、Ｒはハロゲン原子又はアルキル基を示し、波線はジエン系ゴムの上記変性基との結合部位を示す。 From the viewpoint of more effectively and reliably exerting 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).

In the formulas, X represents an anion that forms a salt with pyridinium, L represents _CR2 or a nitrogen atom, _R1 and _R2 each independently represent a hydrogen atom, or an alkyl group, an aryl group, an aralkyl group, an alkenyl group or a monovalent heterocyclic group which may have a substituent, 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, an aryl group, an aralkyl group or an 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 a bonding site with the above-mentioned modifying group of the diene rubber.

X, L, _R1 , _R2 , _R5 and _R6 have the same meanings as those in the above formula (3), and are the same examples and preferred embodiments as those in the above formula (3), so the explanation here is omitted.

The preferred embodiments and examples of the alkyl group in R are the same as those in _R1 and _R2 , and therefore the explanation thereof will be omitted here.

The diene rubber constituting the portion other than the modified 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 terblock copolymer (SIS), and styrene-butadiene-styrene terblock copolymer (SBS).

The natural rubber may be any rubber having a carbon-carbon double bond, and examples of such natural rubber include 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 modified versions of these natural rubbers, are also included in the natural rubber of this embodiment.

Among these, SBR, BR, IR and natural rubber are preferred from the viewpoint of more effectively and reliably exerting the effects of the present invention. These diene-based rubbers may be modified with modifying groups other than the above-mentioned modifying groups (hereinafter referred to as "other modifying groups"). The portion modified with the other modifying groups 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.

The weight average molecular weight of the diene rubber is not particularly limited, and may be, for example, about 2.0 × 10 ⁵ to 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.

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

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 is obtained by kneading the compound (1) with the diene rubber. Also, when synthesizing the modified diene rubber, if the diene rubber is liquid, the modified diene rubber is obtained by mixing a solution or suspension of the diene rubber with the compound (1).

There are no particular limitations on the heating temperature when synthesizing the modified diene rubber. 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.

There are no particular limitations on the kneading or mixing time when synthesizing the modified diene rubber. 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.

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.

(Rubber 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 its description will be omitted here. The filler, as well as 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 their description will be omitted here. Among the above, the diene rubber may contain the diene rubber before the modified diene rubber is modified. The second rubber composition may also contain the above-mentioned compound (1). The compounding amounts of these components in the second rubber composition are the same as those in the first rubber composition, except that the compounding amount is based on the total of 100 parts by mass of the modified diene rubber and the diene rubber instead of 100 parts by mass of the diene rubber. Therefore, the description of the preferred compounding amounts will be omitted.

The second rubber composition of this embodiment may contain rubber other than the modified diene rubber described above, as long as it does not impede the problem-solving of the present invention. Any known rubber may be used as such a rubber.

The second rubber composition of this embodiment is manufactured, for example, by the manufacturing method described below. However, the manufacturing method is not limited to this. That is, the manufacturing method has a kneading and mixing step (B) in which a diene rubber, a compound (1), and a filler are kneaded or mixed while being heated to obtain a rubber composition. Alternatively, the manufacturing method has a kneading step (C) in which the modified diene rubber obtained as described above is kneaded with a filler to obtain a rubber composition.

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.

It is preferable to add the vulcanizing agent and vulcanization accelerator to the kneading and mixing means in the kneading step (D). This makes it possible to more reliably prevent premature scorching. It is also preferable to add the antioxidant and softener that may be contained in the rubber composition to the kneading and mixing means in the kneading and mixing step (B) or (C).

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 fed into the kneading and mixing means, but it is preferable to feed the diene rubber or modified diene rubber first, and then feed the other components. The method of feeding the other components is not particularly limited, but for example, when the components are in powder form, the powder may be fed as is, the components may be dissolved in a solvent and fed as a solution, or the components may be fed as an emulsion solution. In addition, the kneading and mixing in the kneading and mixing steps (B) and (C) are preferably performed in one stage for efficiency, but may be divided into multiple stages as necessary.

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 the 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 interact 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.

As the kneading means in the kneading step (D), the kneading machine exemplified in the kneading and mixing step (B) can be used. In addition, the kneading temperature in the kneading step (D) is preferably 100°C or less from the viewpoint of suppressing the progress of vulcanization.

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

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 compound (1) being 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 the filler, so it is believed that the dispersibility of the filler in the rubber composition is improved. As a result, it is presumed that friction between the fillers is suppressed, resulting in an excellent low heat generation property.

Compound (1) can be used as a dispersant for fillers, a heat reducing agent, a heat prevention material, and a heat suppressant, and more specifically, can be used as a dispersant for rubber, a heat reducing agent for rubber, a heat prevention material for rubber, or a heat suppressant for rubber. The rubber composition of this embodiment can be used, for example, in tires, anti-vibration rubber, conveyor belts, and rubber parts thereof. Among these, when the rubber composition of this embodiment is used in tires, the grip of the tire is improved and the tire can also contribute to low fuel consumption, so it is preferable.

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

Details of each component used in the following Examples and Comparative Examples are given below.
Rubber component: 100 parts by mass, 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 mass, stearic acid, manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd. Anti-aging agent: 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 ^m2 /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 Industries, Ltd. 1 part by mass, 1,3-diphenylguanidine, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

Example 1
(Synthesis of compound (1a))
Compound (1a) represented by 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.
In a 100 mL one-neck flask, 1.58 g (0.01 mol) of 4-cyanopyridine, 1.5 equivalents of bromoethane, and 10 mL of methyl ethyl ketone were added, and a reflux condenser was attached and the mixture was heated and stirred at an external temperature of 80° C. for 6 hours. The reaction liquid was cooled to room temperature, and 30 mL of isopropanol and 30 mL of diethyl ether were added thereto to obtain a suspension. The suspension was filtered and washed with a small amount of chloroform, and then dried under reduced pressure to obtain compound (1a) as 0.98 g of a brown powder. The structure of the obtained powder was analyzed by 1H-NMR, and the results were as follows.
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)

(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 below) whose interior had been heated to 60° C., and kneaded at 60 rpm for 5 minutes.
First kneading and mixing: The masticated rubber component was put into a Banbury mixer heated to 70°C, and kneading was started at a rotation speed of 100 rpm. After 30 seconds, the vulcanization aid, the antiaging agent, carbon black, and 0.5 parts by mass of compound (1a) were added. After 30 seconds, half of the silica was added, and after 60 seconds, the remaining half of the silica sprinkled with the silane coupling agent was added. After that, the cylinder was opened for 1 minute when the rubber temperature reached 140°C. After sealing the cylinder again, the mixture was kneaded until the rubber temperature reached 150°C to obtain a kneaded product.
Second kneading and mixing: Using a 6-inch two-roll kneader (manufactured by Ikeda Kikai Kogyo Co., Ltd.), a vulcanizing agent and a vulcanization accelerator were added to the entire amount of the kneaded product 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 performed 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 property (affinity between rubber and filler) of the vulcanized rubber composition was evaluated as described below and found to be 102.

Incidentally, whether or not the reaction between compound (1a) and diene rubber proceeded was confirmed as follows. That is, in a Banbury mixer at 140°C, 60 parts by mass of isoprene rubber (manufactured by JSR, trade name "IR2000"), 40 parts by mass of styrene-butadiene rubber (manufactured by Nippon Zeon, trade name "NS166"), 1 part by mass of compound (1a), and 10 parts by mass of silica were kneaded for 10 minutes. Acetone insoluble matter was extracted from the kneaded product by Soxhlet extraction using acetone. The extract was analyzed by ^1H -HMR. As a result, it was confirmed that the peak of compound (1a) disappeared and a new peak appeared at 8 to 10 ppm, and from this, it was found that an inverse electron demand type Aza-Diels-Alder reaction proceeded between compound (1a) and the double bond of the rubber.

Example 2
(Synthesis of compound (1b))
Compound (1b) represented by formula (1), in which R ₁ is a hydrogen atom, R ₂ is a hydrogen atom, R ₃ is an n-propyl 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.
In a 100 mL one-neck flask, 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 were added, and the flask was equipped with a reflux condenser and stirred at an external temperature of 80° C. for 12 hours. The reaction liquid was cooled to room temperature, and 30 mL of isopropanol and 30 mL of diethyl ether were added thereto to obtain a suspension. The suspension was filtered and 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 obtained powder was analyzed by 1H-NMR, and the results were as follows.
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)

(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. In addition, the rubber reinforcing property (affinity between rubber and filler) of the vulcanized rubber composition was evaluated as described below and found to be 98.

Example 3
(Synthesis of compound (1c))
Compound (1c) represented by formula (1), in which R ₁ is a hydrogen atom, R ₂ is a hydrogen atom, R ₃ is an n-octyl 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 an iodide ion, was synthesized as follows.
In a 100 mL one-neck flask, 1.58 g (0.01 mol) of 4-cyanopyridine, 1.2 equivalents of octane iodide, and 10 mL of methyl ethyl ketone were added, and the mixture was stirred for 6 hours at an external temperature of 100° C. with a reflux condenser attached. The reaction solution was cooled to room temperature, and 10 mL of isopropanol and 30 mL of diethyl ether were added thereto to obtain a suspension. The suspension was filtered and washed with a small amount of chloroform, and then dried under reduced pressure to obtain compound (1c) as 1.39 g of a brown powder. The structure of the obtained powder was analyzed by 1H-NMR. The results were as follows.
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 to 1.24 (m, 10H), 0.89 (t, J=7.5Hz, 3H)

(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 (1c). The heat buildup of the obtained vulcanized rubber composition was evaluated as described below and found to be 88. In addition, the rubber reinforcing property (affinity between rubber and filler) of the vulcanized rubber composition was evaluated as described below and found to be 101.

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.
In a 100 mL one-neck flask, 1.58 g (0.01 mol) of 3-cyanopyridine, 1.2 equivalents of methyl iodide, and 10 mL of methyl ethyl ketone were added, and the mixture was attached to a reflux condenser and stirred at an external temperature of 80° C. for 4 hours to obtain a suspension. This suspension was filtered and washed with a small amount of chloroform, and then dried under reduced pressure to obtain compound (1d) as 2.79 g of a brown powder. The structure of the obtained 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)

(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 (1d). The heat buildup of the obtained vulcanized rubber composition was evaluated as described below and found to be 91. In addition, the rubber reinforcing property (affinity between rubber and filler) of the vulcanized rubber composition was evaluated as described below and found to be 104.

Example 5
(Synthesis of compound (1e))
Compound (1e) represented by formula (1), in which R ₁ is a hydrogen atom, R ₂ is a hydrogen atom, R ₃ is an ethoxycarbonylmethyl group (-CH ₂ COOC ₂ H ₅ ), 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 one-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, and the flask was equipped with a reflux condenser and stirred for 6 hours at an external temperature of 110° C. 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 were as follows.
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)

(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. In addition, the rubber reinforcing property (affinity between rubber and filler) of the vulcanized rubber composition was evaluated as described below and found to be 107.

Example 6
(Synthesis of compound (1f))
Compound (1f) represented by formula (1), in which R ₁ is a hydrogen atom, R ₂ is a hydrogen atom, R ₃ is an acetamide group (—CH ₂ CONH ₂ ), 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.
In a 100 mL one-neck flask, 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 were added, and the flask was equipped with a reflux condenser and stirred at an external temperature of 100° C. for 6 hours. The reaction liquid 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 and washed with a small amount of chloroform, and then dried under reduced pressure to obtain compound (1f) as 2.47 g of a brown powder. The structure of the obtained powder was analyzed by 1H-NMR, and the results were as follows.
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)

(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 87. In addition, the rubber reinforcing property (affinity between rubber and filler) of the vulcanized rubber composition was evaluated as described below and found to be 110.

(Example 7)
(Synthesis of compound (1g))
Compound (1g) represented by formula (1) in which R ₁ is a hydrogen atom, R ₂ is a hydrogen atom, R ₃ is an ethoxycarbonylmethyl group (-CH ₂ COOC ₂ H ₅ ), 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.
In a 100 mL one-neck flask, 1.58 g (0.01 mol) of 3-cyanopyridine, 1.5 equivalents of ethyl chloroacetate, 9 mL of toluene, and 1 mL of acetonitrile were added, and the mixture was stirred for 6 hours at an external temperature of 100° C. with a reflux condenser attached. The reaction solution 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 and washed with a small amount of chloroform, and then dried under reduced pressure to obtain 1.49 g of compound (1g) as a brown powder. 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)

(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 (1g). The heat buildup of the obtained vulcanized rubber composition was evaluated as described below and found to be 89. In addition, the rubber reinforcing property (affinity between rubber and filler) of the vulcanized rubber composition was evaluated as described below and found to be 100.

(Example 8)
(Synthesis of compound (1h))
Compound (1h) represented by formula (1) in which R ₁ is a hydrogen atom, R ₂ is a hydrogen atom, R ₃ is a 2-butanol group (-CH ₂ CH(OH)C ₂ H ₅ ), 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.
1.58 g (0.01 mol) of 3-cyanopyridine, 1.5 equivalents of butylene oxide, and 20 mL of acetic acid were added to a 100 mL one-neck flask and stirred at room temperature overnight. The solvent of this reaction solution was distilled off, and the residue was washed with a small amount of diethyl ether and then dried under reduced pressure to obtain compound (1h) as 2.46 g of a brown oil. The structure of the obtained compound was analyzed by 1H-NMR, and the results were as follows.
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)

(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 (1h). The heat buildup of the obtained vulcanized rubber composition was evaluated as described below and found to be 82. In addition, the rubber reinforcing property (affinity between rubber and filler) of the vulcanized rubber composition was evaluated as described below and found to be 108.

(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 generation property of the obtained vulcanized rubber composition was evaluated as described below, and was found to be 87. In addition, the reinforcing property of the rubber of the vulcanized rubber composition (the affinity between the rubber and the filler) was evaluated as described below, and was found to be 108.

(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 generation property of the obtained vulcanized rubber composition was evaluated as described below, and was found to be 100. In addition, the rubber reinforcing property (affinity between rubber and filler) of the vulcanized rubber composition was evaluated as described below, and was found to be 100.

(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 property of the vulcanized rubber composition (affinity between rubber and filler) was evaluated as described below and found to be 91.

In the same manner as in Example 1, it was confirmed whether the reaction between compound (1i) and the diene rubber had progressed. As a result, it was confirmed that the peak of compound (1i) remained and did not disappear, which indicated that the reaction between compound (1i) and the rubber had not progressed.

(Comparative Example 3)
A vulcanized rubber composition was obtained in the same manner as in Example 1, except that compound (1a) was changed to 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. In addition, the rubber reinforcing property of the vulcanized rubber composition (affinity between rubber and filler) was evaluated as described below and found to be 103.

In the same manner as in Example 1, it was confirmed whether the reaction between compound (1j) and the diene rubber had proceeded. 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 proceeded between compound (1j) and the double bond of the rubber.

(Evaluation of heat generation)
For each vulcanized rubber composition, a dynamic viscoelasticity measuring device (Seiko Instruments Inc., product name "DMS6100") was used to measure loss tangent (tan δ) at a temperature of 60°C, dynamic strain of 0.5%, and frequency of 10 Hz. The loss tangent value in Comparative Example 1 was set to 100, and the results were evaluated as a relative value. The smaller the value, the lower the tan δ, indicating that the rubber composition has low heat buildup.

(Evaluation of rubber reinforcement)
For each vulcanized rubber composition, a dynamic viscoelasticity measuring device (manufactured by Seiko Instruments Inc., product name "DMS6100") was used to measure the loss tangent (tan δ) at the glass transition temperature of the vulcanized rubber composition, with a dynamic strain of 0.5% and a frequency of 10 Hz. The loss tangent value in Comparative Example 1 was set to 100, and the results were evaluated as a relative value. The larger the value, the higher the tan δ, which indicates a higher affinity between the filler and the rubber in the rubber composition and a higher reinforcing property of the rubber.

According to the present invention, it is possible to provide a compound that can be used as a dispersant for fillers, a heat reducing agent, a heat prevention material, and a heat suppressant, and more specifically, a dispersant for rubber, a heat reducing agent for rubber, a heat prevention material for rubber, or a heat suppressant for rubber. Furthermore, according to the present invention, it is possible to provide a rubber composition that can be used for tires, anti-vibration rubber, conveyor belts, and the rubber parts thereof. Therefore, there is industrial applicability in these fields.

Claims (12)

The present invention includes a compound represented by the following formula (1), a diene rubber, and a filler,
The filler includes at least one selected from the group consisting of inorganic fillers and carbon black.
Rubber composition.
(In formula (1), X represents an anion that forms a salt with pyridinium, L represents _CR2 or a nitrogen atom, _R1 and _R2 each independently represent a hydrogen atom, or an alkyl group, an aryl group, an aralkyl group, an alkenyl group, or a monovalent heterocyclic group which may have a substituent, and _R3 represents an alkyl group, an aryl group, an aralkyl group, or an alkenyl group which may have a substituent which may have one or more selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom.) The rubber composition according to claim 1 , wherein the compound is a compound represented by the following formula (2):
(In formula (2), X represents an anion that forms a salt with pyridinium; L represents _CR2 or a nitrogen atom; _R1 and _R2 each independently represent a hydrogen atom, or an alkyl group, an aryl group, an aralkyl group, an alkenyl group, or a monovalent heterocyclic group which may have a substituent; and _R7 represents a hydrogen atom, or an alkyl group, an aryl group, an aralkyl group, or an 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 amido group, an epoxy group, a sulfanyl group, and an alkylsulfanyl group.) The rubber composition according to claim 1 , wherein the compound is a compound represented by the following formula (3):
(In formula (3), X represents an anion that forms a salt with pyridinium; L represents _CR2 or a nitrogen atom; _R1 and _R2 each independently represent a hydrogen atom, or an alkyl group, aryl group, aralkyl group, alkenyl group or monovalent heterocyclic group which may have a substituent; 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 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 rubber composition according to claim 3, wherein said Z is a group represented by --NR ₆ --. The rubber composition according to any one of claims 1 to 4, wherein R ₁ and R ₂ are hydrogen atoms. The rubber composition according to any one of claims 1 to 5, wherein the diene rubber includes at least one selected from the group consisting of styrene-butadiene rubber, butadiene rubber, isoprene rubber, and natural rubber. The rubber composition according to any one of claims 1 to 6, wherein the filler contains at least one selected from the group consisting of carbon black and silica. The rubber composition according to any one of claims 1 to 7, further comprising a silane coupling agent. The rubber composition according to any one of claims 1 to 8, further comprising sulfur and a vulcanization accelerator. 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).
(In each formula, X represents an anion that forms a salt with pyridinium, L represents _CR2 or a nitrogen atom, _R1 and _R2 each independently represent a hydrogen atom, or an alkyl group, an aryl group, an aralkyl group, an alkenyl group or a monovalent heterocyclic group which may have a substituent, _R3 represents an alkyl group, an aryl group, an aralkyl group or an alkenyl group which may have one or more substituents selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom, R represents a halogen atom or an alkyl group, and the wavy line represents a bonding site with the modifying group of the diene rubber.) The modified diene rubber according to claim 10, wherein R ₁ and R ₂ each independently represent a hydrogen atom or a methyl group. The modified diene rubber according to claim 10 or 11 and a filler ,
The filler includes at least one selected from the group consisting of inorganic fillers and carbon black.
Rubber composition.