JP6873744B2 - Rubber composition and tires using it - Google Patents

Description

The present invention relates to a rubber composition and a tire using the same.

In recent years, from the viewpoints of resource saving, energy saving, and environmental protection, regulations on exhaust gas such as carbon dioxide have become stricter, and the demand for fuel efficiency improvement for automobiles is extremely increasing. Therefore, as a common issue for automobiles, it is required to improve fuel efficiency by improving the rolling resistance of tires.

As a method for reducing the rolling resistance of a tire, it is known to apply a rubber composition having low heat generation to the tire. Examples of such a low heat-generating rubber composition include (1) a rubber composition containing a functionalized polymer having an enhanced affinity with carbon black as a filler and silica (Patent Document 1); (2). ) A rubber composition containing a diene elastomer, an inorganic filler as a reinforcing filler, an alkoxysilane polysulfide as a coupling agent, 1,2-dihydropyridine, and a guanidine derivative (Patent Document 2); (3) Rubber component, aminopyridine derivative. And a rubber composition containing an inorganic filler (Patent Document 3); (4) a rubber composition containing a terminal-modified polymer and an inorganic filler (Patent Documents 4 and 5) and the like.

According to the inventions described in Patent Documents 1 to 5, the heat generation of the rubber composition can be lowered by increasing the affinity between the filler and the rubber component, and as a result, hysteresis loss (rolling) can be achieved. A tire with low resistance) can be obtained.

However, even if the rubber compositions of Patent Documents 1 to 5 are used, the effect of reducing heat generation is insufficient, and a tire having satisfactory fuel efficiency cannot be obtained.

By the way, it has been reported that a dihydrotetrazine derivative represented by the following formula (i) is added to a rubber composition and used (Patent Document 6).

[In the formula, R represents an alkyl group, an aryl group, an alalkyl group, and R'and R "represent a hydrogen atom or an aryl group.]
Although Patent Document 6 describes that these dihydrotetrazine derivatives have the effect of preventing deterioration, aging, etc. of the rubber composition due to oxidation, the heat generation is reduced by suppressing or preventing heat generation. There is no mention of any effects related to. In fact, these tetrazine derivatives have almost no effect of lowering the heat generation of the rubber composition (see the comparative example below).

As described above, the demand for low fuel consumption of automobiles is further increasing, but tires having satisfactory fuel consumption performance have not been obtained, and the development of tires having extremely excellent low heat generation is eagerly desired.

Japanese Unexamined Patent Publication No. 2003-514079 Japanese Patent Application Laid-Open No. 2003-523472 Japanese Unexamined Patent Publication No. 2013-108004 Japanese Unexamined Patent Publication No. 2000-169631 Japanese Unexamined Patent Publication No. 2005-220323 Japanese Unexamined Patent Publication No. 49-47439

An object of the present invention is to provide a rubber composition capable of exhibiting low heat generation.

One of the other objects of the present invention is to provide a tire having excellent low heat generation.

As a result of diligent studies to solve the above problems, the present inventors have discovered that a rubber composition containing a specific dihydrotetrazine-based compound and an oxidizing agent exhibits further excellent low heat buildup. .. The present inventors have completed the present invention as a result of further studies based on such findings.

That is, the present invention provides the rubber composition, the method for producing the rubber composition, and the tire shown below.
Item 1. A rubber composition containing a rubber component, a dihydrotetrazine compound represented by the following general formula (1) or a salt thereof, an oxidizing agent, and a carbon black and / or an inorganic filler.

[In the formula, X ¹ and X ² represent heterocyclic groups that may have an alkoxycarbonyl group, a carboxyl group, an amide group, or a substituent, which may be the same or different. ]
Item 2. Item 2. The rubber composition according to Item 1, wherein the dihydrotetrazine compound is a dihydrotetrazine compound in the general formula (1), wherein X ¹ and X ^{2 are heterocyclic groups which may have a substituent.}
Item 3. The total amount of the dihydrotetrazine compound represented by the general formula (1) or a salt thereof of 0.1 to 10 parts by mass, carbon black and / or an inorganic filler is 20 to 150 parts by mass with respect to 100 parts by mass of the rubber component. A rubber composition containing a part and 0.1 to 30 mol of an oxidizing agent with respect to 1 mol of the dihydrotetrazine compound represented by the general formula (1) or a salt thereof.
Item 4. Oxidizing agents are oxygen, ozone, halogen, halogen oxo acid and its salts, peroxides, superatomic iodine compounds, metal oxides, chromium acid compounds, persulfate compounds, metal complex compounds, nitroxy radical compounds, N- Item 2. The rubber composition according to any one of Items 1 to 3, which is at least one selected from the group consisting of halogenimide compounds, N-oxide compounds, quinone compounds, nitrates, nitrites, and nitrite esters.
Item 5. The rubber composition according to any one of Items 1 to 4, wherein the rubber component is a diene-based rubber.
Item 6. Item 2. The rubber composition according to any one of Items 1 to 5, wherein the rubber component contains 50% by mass or more of diene-based rubber.
Item 7. Item 2. The rubber composition according to any one of Items 1 to 6, wherein the rubber component contains 70% by mass or more of diene-based rubber.
Item 8. Item 2. The rubber composition according to any one of Items 1 to 7, which is used for at least one member selected from a tread portion, a sidewall portion, a bead area portion, a belt portion, a carcass portion and a shoulder portion.
Item 9. Item 2. The rubber composition according to any one of Items 1 to 7, which is used for at least one member selected from the group consisting of a tread portion and a sidewall portion.
Item 10. Item 2. The rubber composition according to any one of Items 1 to 7, which is used for a member of a tread portion.
Item 11. A tire produced by using the rubber composition according to any one of Items 1 to 10.
Item 12. In the step (A) and the step (A) of mixing the rubber component, the dihydrotetrazine compound represented by the general formula (1) or a salt thereof, the oxidizing agent, and the raw material component containing the inorganic filler and / or carbon black. A method for producing a rubber composition, which comprises a step (B) of mixing the obtained mixture and a vulcanizing agent.
Item 13. The step (A) was obtained in the step (A-1) of mixing the rubber component, the dihydrotetrazine compound represented by the general formula (1) or a salt thereof, and the oxidizing agent, and the step (A-1). Item 12. The production method according to Item 12, wherein the step (A-2) of mixing the mixture and the inorganic filler and / or carbon black.

The present invention can provide a rubber composition capable of exhibiting low heat generation.

INDUSTRIAL APPLICABILITY The present invention provides a fuel-efficient tire because the rolling resistance of the tire can be reduced and the heat generation of the tire can be reduced by producing the tire using a rubber composition capable of exhibiting low heat generation. can do. Further, since a rubber composition highly filled with silica also exhibits high heat generation, it is possible to provide a fuel-efficient tire having high steering stability performance.

Hereinafter, the present invention will be described in detail.

1. 1. Rubber Composition The rubber composition of the present invention is a rubber component, a dihydrotetrazine compound represented by the formula (1) or a salt thereof (hereinafter, may be referred to as “dihydrotetrazine compound (1)”), an oxidizing agent. , And an inorganic filler and / or carbon black.

[In the formula, X ¹ and X ² represent heterocyclic groups that may have an alkoxycarbonyl group, a carboxyl group, an amide group, or a substituent, which may be the same or different. ]

In the rubber composition of the present invention, the blending amount of the dihydrotetrazine compound (1) is usually 0.1 to 10 parts by mass, preferably 0.25 to 5 parts by mass with respect to 100 parts by mass of the rubber component. Yes, more preferably 0.5 to 2 parts by mass.

The amount of the oxidizing agent to be blended is preferably 0.1 to 30 mol, more preferably 0.3 to 20 mol, based on 1 mol of the compound represented by the dihydrotetrazine compound (1) to be blended. It is preferably 0.5 to 10 mol, more preferably 0.5 to 10 mol.

The blending amount of the inorganic filler is usually 20 to 150 parts by mass, preferably 30 to 120 parts by mass, and more preferably 40 to 90 parts by mass with respect to 100 parts by mass of the rubber component.

The blending amount of carbon black is usually 2 to 150 parts by mass, preferably 4 to 120 parts by mass, and more preferably 6 to 100 parts by mass with respect to 100 parts by mass of the rubber component.

In the rubber composition of the present invention, the inorganic filler and / or carbon black is the total amount of both components, for example, 20 to 150 parts by mass, preferably 40 to 130 parts by mass with respect to 100 parts by mass of the rubber component. Each component may be appropriately adjusted within the above-mentioned blending amount so as to be parts by mass, more preferably 45 to 100 parts by mass.

When the total amount of the inorganic filler and / or carbon black is 20 parts by mass or more, it is preferable from the viewpoint of improving the reinforcing property of the rubber composition, and when it is 150 parts by mass or less, it is preferable from the viewpoint of reducing rolling resistance. .. When blending the inorganic filler and / or carbon black, a master batch in which the polymer is mixed wet or dry in advance may be used.

The inorganic filler or carbon black is usually used to improve the reinforcing property of rubber. In this specification, carbon black is not included in the inorganic filler.

Rubber component The rubber component used in the production of the rubber composition of the present invention is not particularly limited, and is, for example, natural rubber (NR), synthetic diene rubber, a mixture of natural rubber and synthetic diene rubber, and these. Other non-diene rubbers can be mentioned, but in order to develop and maintain excellent low heat generation, it is preferable to contain a diene rubber.

The content of the diene rubber is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 100% by mass in the rubber component.

Examples of natural rubber include natural rubber latex, technical rating rubber (TSR), smoked sheet (RSS), backlash, Tochu-derived natural rubber, Guayur-derived natural rubber, Russian dandelion-derived natural rubber, and plant-based fermented rubber. Further, modified natural rubbers such as epoxidized natural rubber, methacrylic acid-modified natural rubber, styrene-modified natural rubber, sulfonic acid-modified natural rubber, and zinc sulfonate-modified natural rubber, which are modified from these natural rubbers, are also the natural rubbers of the present invention. include.

Examples of synthetic diene rubbers include styrene-butadiene copolymer rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), nitrile rubber (NBR), chloroprene rubber (CR), and ethylene-propylene-diene ternary products. Polymer rubber (EPDM), styrene-isoprene-styrene ternary block copolymer (SIS), styrene-butadiene-styrene ternary block copolymer (SBS), ethylene-α-olefin copolymer rubber (SPO), ethylene Examples thereof include -α-olefin-diene copolymer rubber and the like, and modified synthetic diene-based rubbers thereof. The modified synthetic diene rubber includes a diene rubber obtained by a modification method such as main chain modification, single-ended modification, and double-ended modification. Here, examples of the modified functional group of the modified synthetic diene rubber include various functional groups such as an epoxy group, an amino group, an alkoxysilyl group, and a hydroxyl group, and one or more of these functional groups are modified synthetic diene type. It may be contained in the rubber.

The method for producing the synthetic diene-based rubber is not particularly limited, and examples thereof include emulsion polymerization, solution polymerization, radical polymerization, anionic polymerization, and cationic polymerization. Further, the glass transition point of the synthetic diene rubber is not particularly limited.

Further, the ratio of cis / trans / vinyl in the double bond portion of the natural rubber and the synthetic diene rubber is not particularly limited, and any ratio can be preferably used. The number average molecular weight and the molecular weight distribution of the diene rubber are not particularly limited, but the number average molecular weight is preferably 500 to 3000000 and the molecular weight distribution is preferably 1.5 to 15.

As the non-diene rubber, known rubbers can be widely used.

The rubber component can be used alone or in combination of two or more. Among them, the preferable rubber component is natural rubber, IR, SBR, BR or a mixture of two or more kinds selected from these, and more preferably natural rubber, SBR, BR or a mixture of two or more kinds selected from these. .. The blending ratio thereof is not particularly limited, but it is preferable to mix SBR, BR or a mixture thereof in 100 parts by mass of the rubber component at a ratio of 50 to 100 parts by mass, preferably 75 to 100 parts by mass. It is particularly preferable to blend. When blending a mixture of SBR and BR, the total amount of SBR and BR is preferably in the above range. Further, the SBR at this time is 50 to 100 parts by mass, and the BR is preferably in the range of 0 to 50 parts by mass.

Dihydrotetrazine compound (1)
The rubber composition of the present invention contains a dihydrotetrazine compound represented by the following general formula (1) or a salt thereof.

[In the formula, X ¹ and X ² represent heterocyclic groups that may have an alkoxycarbonyl group, a carboxyl group, an amide group, or a substituent, which may be the same or different. ]

In the present specification, the "alkoxycarbonyl group" is not particularly limited, and is, for example, a linear or branched linear or branched group having 1 to 6 carbon atoms (particularly 1 to 4 carbon atoms) such as a methoxycarbonyl group and an ethoxycarbonyl group. Alkoxy-carbonyl groups can be mentioned.

In the present specification, the "amide group" is not particularly limited, and for example, a carboxylic acid amide group such as an acetamido group or a benzamide group; a thioamide group such as a thioacetamide group or a thiobenzamide group; an N-methylacetamide group or N. -N-substituted amide groups such as benzylacetamide groups; and the like.

In the present specification, the "heterocyclic group" is not particularly limited, and for example, 2-pyridyl group, 3-pyridyl group, 4-pyridyl group, 2-pyrazinyl group, 2-pyrimidyl group, 4-pyrimidyl group, and the like. 5-pyrimidyl group, 3-pyridadyl group, 4-pyridadyl group, 4- (1,2,3-triazyl) group, 5- (1,2,3-triadyl) group, 2- (1,3,5-) Triasyl) group, 3- (1,2,4-triazyl) group, 5- (1,2,4-triazil) group, 6- (1,2,4-triazil) group, 2-quinolyl group, 3- Quinoline 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- Synoryl group, 5-Synolinyl group, 6-Synolyl group, 7-Synolinyl group, 8-Synolinyl group, 2-Kynazolyl group, 4-Kynazolyl group, 5-Kynazolyl group, 6-Kynazolyl group, 7-Kynazolyl group, 8- Kinazolyl 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-tetrahydro Quinoline group, 4-tetrahydroquinolyl group, 5-tetrahydroquinolyl group, 6-tetrahydroquinolyl group, 7-tetrahydroquinolyl group, 8-tetrahydroquinolyl group, 1-pyrrrolyl group, 2-pyrrolill 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-isooxazolyl group, 4 -Isooxazolyl 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-thiazol) group, 2- (1,3,4-thiazol) , 4- (1,2,3-oxadiazolyl) group, 5- (1,2,3-oxadiazolyl) group, 3- (1,2,4-oxadiazolyl) group, 5- (1,2, 4- (1,2,5-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-indrill group, 2-indrill group, 3-indrill group, 4-indrill group, 5-indrill group, 6-indrill group, 7-Indrill group, 1-isoindrill group, 2-isoindrill group, 3-isoindrill group, 4-isoindrill group, 5-isoindrill group, 6-isoindrill group, 7-isoindrill group, 1-benzoimidazolyl group, 2-benzoimidazolyl group, 4-benzoimidazolyl group, 5-benzoimidazolyl group, 6-benzoimidazolyl group, 7-benzoimidazolyl 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-isobenzofunyl group, 2-benzothienyl group , 3-benzothienyl group, 4-benzothienyl group, 5-benzothienyl group, 6-benzothienyl group, 7-benzothienyl group, 2-benzoxazolyl group, 4-benzoxazolyl group, 5-benzo Oxazolyl 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-Molholyl group, 3-Morphoryl group, 4-Morphoryl group, 1-Piperazyl group, 2-Piperazyl group , 1-piperidyl group, 2-piperidyl group, 3-piperidyl group, 4-piperidyl group, 2-tetrahydropyranyl group, 3-tetrahydropyranyl group, 4-tetrahydropyranyl group, 2-tetrahydrothiopyrani Lu group, 3-tetrahydrothiopyranyl group, 4-tetrahydrothiopyranyl group, 1-pyrrolidyl group, 2-pyrrolidyl group, 3-pyrrolidyl group, 2-tetrahydrofuranyl group, 3-tetrahydrofuranyl group, 2-tetrahydrothienyl Groups, 3-tetrahydrofuranyl groups and the like can be mentioned. Among them, the preferred heterocyclic group is a pyridyl group, a furanyl group, a thienyl group, a pyrimidyl group or a pyrazil group, and more preferably a pyridyl group.

These heterocyclic groups may have one or more substituents at arbitrary positions. The "substituent" is not particularly limited, and is, for example, 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, or a nitrile group. , Nitro group, alkyl group, hydroxyalkyl group, hydroxyl group, alkoxy group, aryl group, aryloxy group, heterocyclic group, thiol group, alkylthio group, arylthio group and the like. The substituent may preferably have 1 to 5, more preferably 1 to 3.

In the present specification, examples of the "halogen atom" include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, preferably a chlorine atom, a bromine atom, and an iodine atom.

In the present specification, the "amino group" includes _{not only the amino group represented by -NH 2} , but also, for example, a methylamino group, an ethylamino group, an n-propylamino group, an isopropylamino group, and an n-butylamino group. , Isobutylamino group, s-butylamino group, t-butylamino group, 1-ethylpropylamino group, n-pentylamino group, neopentylamino group, n-hexylamino group, isohexylamino group, 3-methylpentyl Linear or branched monoalkylamino groups having 1 to 6 carbon atoms (particularly 1 to 4 carbon atoms) such as amino groups; 1 to 6 carbon atoms such as dimethylamino groups, ethylmethylamino groups and diethylamino groups (particularly). Substituted amino groups such as a dialkylamino group having two linear or branched alkyl groups having 1 to 4 carbon atoms are also included.

In the present specification, the "aminoalkyl group" is not particularly limited, and for example, an aminoalkyl group such as an aminomethyl group, a 2-aminoethyl group, or a 3-aminopropyl group (preferably having an amino group and having 1 carbon number). ~ 6 linear or branched alkyl groups).

In the present specification, the "acyl group" is not particularly limited, and examples thereof include linear or branched alkylcarbonyl groups having 1 to 4 carbon atoms such as acetyl, propionyl, and pivaloyl groups.

In the present specification, the "acyloxy group" is not particularly limited, and examples thereof include an acetyloxy group, a propionyloxy group, and an n-butyryloxy group.

In the present specification, the "carboxyalkyl group" is not particularly limited, and for example, a carboxymethyl group, a carboxyethyl group, a carboxy-n-propyl group, a carboxy-n-butyl group, a carboxy-n-butyl group, and a carboxy group. Examples thereof include a carboxy-alkyl group such as an −n—hexyl group (preferably an alkyl group having a carboxy group and having 1 to 6 carbon atoms).

In the present specification, the "alkyl group" is not particularly limited, and examples thereof include linear, branched or cyclic alkyl groups, and specific examples thereof include methyl group, ethyl group and n-propyl. Group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, 1-ethylpropyl group, n-pentyl group, neopentyl group, n-hexyl group, isohexyl group, 3-methylpentyl group Linear or branched alkyl groups having 1 to 6 carbon atoms (particularly 1 to 4 carbon atoms); cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, etc. Examples thereof include a cyclic alkyl group having ~ 8 (particularly 3 to 6 carbon atoms).

In the present specification, the "hydroxyalkyl group" is not particularly limited, and for example, hydroxy such as a hydroxymethyl group, a 2-hydroxyethyl group, a 3-hydroxy-n-propyl group, and a 4-hydroxy-n-butyl group. -Alkyl groups (preferably alkyl groups having a hydroxy group and having 1 to 6 carbon atoms) can be mentioned.

In the present specification, the "alkoxy group" is not particularly limited, and examples thereof include linear, branched or cyclic alkoxy groups, and specific examples thereof include methoxy group, ethoxy group and n-propoxy. A linear group having 1 to 6 carbon atoms (particularly 1 to 4 carbon atoms) of a group, an isopropoxy group, an n-butoxy group, a t-butoxy group, an n-pentyloxy group, a neopentyloxy group, and an n-hexyloxy group. Or a branched alkoxy group; having 3 to 8 carbon atoms (particularly 3 to 6 carbon atoms) such as a cyclopropyloxy group, a cyclobutyloxy group, a cyclopentyloxy group, a cyclohexyloxy group, a cycloheptyloxy group, and a cyclooctyloxy group. Cyclic alkoxy groups and the like can be mentioned.

In the present specification, the "aryl group" is not particularly limited, and examples thereof include a phenyl group, a biphenyl group, a naphthyl group, a dihydroindenyl group, and a 9H-fluorenyl group. More preferable aryl groups include phenyl groups and naphthyl groups.

In the present specification, the "aryloxy group" is not particularly limited, and examples thereof include a phenoxy group, a biphenyloxy group, and a naphthoxy group.

In the present specification, the "alkylthio group" is not particularly limited, and examples thereof include linear, branched or cyclic alkylthio groups, and specifically, for example, methylthio group, ethylthio group and n-propylthio. Group, isopropylthio group, n-butylthio group, isobutylthio group, s-butylthio group, t-butylthio group, 1-ethylpropylthio group, n-pentylthio group, neopentylthio group, n-hexylthio group, isohexylthio Linear or branched alkylthio groups having 1 to 6 carbon atoms (particularly 1 to 4 carbon atoms) such as groups and 3-methylpentylthio groups; cyclopropylthio groups, cyclobutylthio groups, cyclopentylthio groups, cyclohexylthios. Examples thereof include a cyclic alkylthio group having 3 to 8 carbon atoms (particularly 3 to 6 carbon atoms) such as a group, a cycloheptylthio group and a cyclooctylthio group.

In the present specification, the "arylthio group" is not particularly limited, and examples thereof include phenylthio, biphenylthio, and naphthylthio groups.

The "salt" of the dihydrotetrazine compound represented by the general formula (1) is not particularly limited and includes all kinds of salts. Examples of such salts include inorganic acid salts such as hydrochlorides, sulfates and nitrates; organic acid salts such as acetates and methanesulfonates; alkali metal salts such as sodium salts and potassium salts; magnesium salts and calcium. Alkaline earth metal salts such as salts; quaternary ammonium salts such as dimethylammonium and triethylammonium can be mentioned.

Among these dihydrotetrazine compounds (1), a preferable compound is a compound in which X ¹ and X ² are heterocyclic groups which may have the same or different substituents.

In the more preferable dihydrotetrazine compound (1), X ¹ and X ² are the same or different, 2-pyridyl group which may have a substituent, and 3-pyridyl group which may have a substituent. , 4-pyridyl group which may have a substituent, 2-furanyl group which may have a substituent, thienyl group which may have a substituent, and may have a substituent. It is a compound which is a 1-pyrazolyl group, a 2-pyrimidyl group which may have a substituent, or a 2-pyrazyl group which may have a substituent, and among these, a compound which has a substituent and has a substituent. A compound which is a 2-pyridyl group, a 3-pyridyl group which may have a substituent, or a 4-pyridyl group which may have a substituent is particularly preferable.

Specifically, examples of the dihydrotetrazine compound (1) include 1,2-dihydro-3,6-bis (2-pyridyl) -1,2,4,5-tetrazine and 1,2-dihydro-3. , 6-bis (3-pyridyl) -1,2,4,5-tetrazine, 1,2-dihydro-3,6-bis (4-pyridyl) -1,2,4,5-tetrazine, 1,2 -Dihydro-3,6-bis (2-furanyl) -1,2,4,5-tetrazazine, 1,2-dihydro-3,6-bis (3,5-dimethyl-1-pyrazolyl) -1,2 , 4,5-Tetrazine, 1,2-Dihydro-3,6-bis (2-thienyl) -1,2,4,5-Tetrazine, 1,2-Dihydro-3,6-bis (2-pyrimidinyl) -1,2,4,5-Tetrazine, 1,2-Dihydro-3,6-bis (2-pyrazyl) -1,2,4,5-Tetrazine, 1,2-Dihydro-1,2,4 5-Tetrazine-3,6-dicarboxylic acid, dimethyl 1,2-dihydro-1,2,4,5-tetrazine-3,6-dicarboxylic acid, 1,2-dihydro-1,2,4,5-dihydro Tetrazine-3,6-dicarboxylicamide, 1,4-dihydro-3,6-bis (2-pyridyl) -1,2,4,5-tetrazine, 1,4-dihydro-3,6-bis (3) −Pyridyl) -1,2,4,5-Tetrazine, 1,4-dihydro-3,6-bis (4-Pyridyl) -1,2,4,5-Tetrazine, 1,4-dihydro-3,6 -Bis (2-furanyl) -1,2,4,5-tetrazine, 1,4-dihydro-3,6-bis (3,5-dimethyl-1-pyrazolyl) -1,2,4,5-tetrazine , 1,4-dihydro-3,6-bis (2-thienyl) -1,2,4,5-tetrazine, 1,4-dihydro-3,6-bis (2-pyrimidinyl) -1,2,4 , 5-Tetrazine, 1,4-dihydro-3,6-bis (2-pyrazyl) -1,2,4,5-Tetrazine, 1,4-Dihydro-1,2,4,5-Tetrazine-3, 6-Dicarboxylic acid, dimethyl 1,4-dihydro-1,2,4,5-tetrazine-3,6-dicarboxylic acid, 1,4-dihydro-1,2,4,5-dihydrotetrazine-3,6 − Dicarboxylic amide and the like.

Among them, the preferred dihydrotetrazine compound (1) is 1,2-dihydro-3,6-bis (2-pyridyl) -1,2,4,5-tetrazine and 1,2-dihydro-3,6-bis. (3-Pyridyl) -1,2,4,5-Tetrazine, 1,2-Dihydro-3,6-bis (4-Pyridyl) -1,2,4,5-Tetrazine, 1,4-Dihydro-3 , 6-bis (2-pyridyl) -1,2,4,5-tetrazine, 1,4-dihydro-3,6-bis (3-pyridyl) -1,2,4,5-tetrazine, and 1, 4-Dihydro-3,6-bis (4-pyridyl) -1,2,4,5-tetrazine.

The dihydrotetrazine compound (1) includes a 1,4-dihydrotetrazine compound represented by the following general formula (1-1) and a 1,2-dihydrotetrazine compound represented by the general formula (1-2). , Or any mixture thereof is included, and in the present invention, these compounds can be used alone or in combination of two.

[In the formula, X ¹ and X ² are the same as described above. ]

When the dihydrotetrazine compound (1) is a powder, its volume average diameter is not particularly limited. From the viewpoint of low exothermic development, the volume average diameter is preferably 300 μm or less, more preferably 150 μm or less, and particularly preferably 75 μm or less.

The volume average diameter can be obtained from the volume reference particle size distribution as a particle size corresponding to 50% of the integrated distribution curve by using a particle size distribution measuring device such as a laser light diffraction method.

Further, from the viewpoint of handleability during handling and reduction of ignitability or explosive risk, powder may be surface-treated with oil, resin or the like, or the powder may be a filler such as calcium carbonate or silica. It may be mixed with such as.

By adding the dihydrotetrazine compound (1) to the rubber component, low heat generation can be imparted to the rubber component. A tire produced (manufactured) from a rubber composition containing such a dihydrotetrazine compound (1) can impart low heat generation, so that rolling resistance is reduced, and as a result, low fuel consumption performance is exhibited.

The oxidizing agent that can be used in combination with the oxidizing agent dihydrotetrazine Compound (1), for example, oxygen, ozone, halogens, halogen oxo acids, peroxides, hypervalent iodine compounds, metal oxides, chromic acid compound, persulfate Examples thereof include compounds, metal complex compounds, nitroxyl radical compounds, N-halogenimide compounds, N-oxide compounds, quinone compounds, nitrates, nitrites, and nitrite esters.

Examples of the halogen include fluorine, bromine, chlorine, iodine and the like.

Examples of halogen oxo acids include hypobromous acid, bromous acid, bromic acid, perbromic acid, hypochlorous acid, chloric acid, chloric acid, perchloric acid, hypoiodous acid, bromic acid, and iodic acid. Examples thereof include periodous acid and salts thereof.

Peroxides include hydrogen peroxide, barium peroxide, calcium peroxide, lithium peroxide, magnesium peroxide, potassium peroxide, sodium peroxide, lead peroxide, strontium peroxide, potassium superoxide, sodium superoxide, Examples thereof include sodium peroxide, sodium peroxide, zinc peroxide, rubidium peroxide, and cesium peroxide. In addition, as peroxides other than the above, acyl peroxides such as peracetic acid and m-chloroperbenzoic acid; ketone peroxides such as methyl ethyl ketone peroxide, cyclohexanone peroxide and acetylacetone peroxide; 1,1-di (t-). Peroxyketars such as hexylperoxy) -3,3,5-trimethylcyclohexane, 1,1-di (t-butylperoxy) -2-methylcyclohexane, 2,2-di (t-butylperoxy) butane Hydroperoxides such as diisopropylbenzene hydroperoxide, p-menthane hydroperoxide, t-butyl hydroperoxide; di (2-t-butylperoxyisopropyl) benzene, dicumyl peroxide, di-t-hexylper Dialkyl peroxides such as oxides; Diacyl peroxides such as diisobutyl peroxide, dilauryl peroxide, dibenzoyl peroxide; cumylperoxyneodecanoate, t-hexylperoxypivalate, t-hexylperoxy-2. Peroxyesters such as −ethylhexanoate; peroxydicarbonates such as di-n-propylperoxydicarbonate, diisopropylperoxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate and the like can be mentioned. ..

Examples of the periodinane iodine compound include (dichloro) iodine benzene, (bis (trifluoroacetoxy) iodine) benzene, pentafluoro (bis (trifluoroacetoxy) iodine) benzene, (diacetoxyiodine) benzene, and bis (pyridine) iodinenium. Tetrafluoroborate, 2-iodoxybenzoic acid, 1,1,1-triacetoxy-1,1-dihydro-1,2-benzoiodoxol-3- (1H) -one, diphenyliodonium chloride, periodinane Trisodium, (hydroxy (tosyloxy) iodine) benzene2-iodoxybenzenesulfonic acid, 2,2'-diiodo-4,4', 6,6'-tetramethyl-1,1'-biphenyl, 2,2' -Diiodo-5,5'-dimethoxy-1,1'-biphenyl and the like can be mentioned.

Metal oxides include copper oxide, silver oxide, iron oxide, ruthenium oxide, cobalt oxide, rhodium oxide, iridium oxide, nickel oxide, palladium oxide, titanium oxide, vanadium oxide, zinc oxide, molybdenum oxide, platinum oxide, and cadmium oxide. , Chromium oxide, lead oxide, selenium dioxide, samarium oxide, osmium tetraoxide, potassium permanganate, sodium permanganate, ammonium permanganate, silver permanganate, zinc permanganate, magnesium permanganate, permanganic acid Calcium, barium permanganate, manganese oxide, manganese dioxide, sodium manganate, potassium manganate, barium manganate, hexaammonium heptamolybate, vanadium (IV) bis (acetylacetonato) oxide, selenium dioxide, methyltrioxorenium , Propylammonium perlutenate and the like.

Examples of the chromic acid compound include pyridinium chlorochromate and pyridinium dichromate.

Examples of the persulfate compound include oxone and ammonium peroxodisulfate.

Examples of the metal complex compound include aluminum isopropoxide, titanium tetraisopropoxide, potassium hexacyanoferrate, cerium (IV) ammonium nitrate (CAN) and the like.

Examples of the nitroxyl radical compound include 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO), 2-azaadamantane N-oxyl (AZADO), and 1-methyl-2-azaadamantane N-oxyl (1). -Me-AZADO), 2-hydroxy-2-azaadamantane (AZADOL), 9-azabicyclo [3,3,1] nonane N-oxyl (ABNO), 2-azatricyclo [3,2,1,1] nonan 2 -Oxide (Nor-AZADO), 5-fluoro-2-azaadamantane N-oxyl (5-F-AZADO) and the like can be mentioned.

Examples of the N-halogenimide compound include N-iodosuccinimide (NIS), N-chlorosuccinimide (NCS), N-bromosuccinimide (NBS) and the like.

Examples of N-oxide compounds include 2,6-dichloropyridine N-oxide, pyridine N-oxide, nicotinic acid N-oxide, 2,6-dimethylpyridine N-oxide, 4-nitroquinoline 1-oxide, and 2-methyl-. Examples thereof include 4-nitropyridine 1-oxide and 4-methylmorpholin N-oxide.

Examples of the quinone compound include 1,4-benzoquinone, 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), tetrachloro-1,4-benzoquinone and the like.

Nitrate includes potassium nitrate, sodium nitrate, magnesium nitrate, aluminum nitrate, calcium nitrate, scandium nitrate, titanium nitrate, vanadium nitrate, chromium nitrate, manganese nitrate, iron nitrate, cobalt nitrate, nickel nitrate, copper nitrate, zinc nitrate, gallium nitrate. , Germanium nitrate, rubidium nitrate, strontium nitrate, yttrium nitrate, zirconium nitrate, niobite, ruthenium nitrate, rhodium nitrate, palladium nitrate, silver nitrate, barium nitrate and the like.

Examples of nitrites include potassium nitrite, sodium nitrite, magnesium nitrite, aluminum nitrite, calcium nitrite, scandium nitrite, titanium nitrite, vanadium nitrite, chromium nitrite, manganese nitrite, iron nitrite, and nitrite. Cobalt, nickel nitrite, copper nitrite, zinc nitrite, gallium nitrite, germanium nitrite, rubidium nitrite, strontium nitrite, yttrium nitrite, zirconium nitrite, niobite nitrite, ruthenium nitrite, rhodium nitrite, Examples thereof include palladium nitrite, silver nitrite, and barium nitrite.

Examples of nitrites include methyl nitrite, ethyl nitrite, n-propyl nitrite, amyl nitrite, isoamyl nitrite, isobutyl nitrite, isopropyl nitrite, t-butyl nitrite, n-butyl nitrite, and nitrite. Hexil and the like can be mentioned.

Among these, periodinane compounds, metal oxides, persulfate compounds, metal complex compounds, N-halogenimide compounds, quinone compounds, and nitrites are preferable, and (diacetoxyiode) benzene and potassium permanganate are particularly preferable. Ammonium peroxodisulfate, imide N-bromosuccinate (NBS), 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), sodium nitrite, and cerium (IV) ammonium nitrate (CAN) are preferred. In the present invention, one type of oxidizing agent may be used alone, or two or more types may be used in combination.

The amount of these oxidizing agents used is not particularly limited, and is preferably 0.1 to 30 mol, preferably 0.3 to 20 mol, with respect to 1 mol of the compound represented by the dihydrotetrazine compound (1) to be blended. It is more preferably mol, and even more preferably 0.5-10 mol.

Inorganic filler The inorganic filler is not particularly limited as long as it is an inorganic compound usually used in the rubber industry. Examples of the inorganic compounds that can be used include silica; alumina such as γ-alumina and α-alumina (Al ₂ O ₃ ); alumina monohydrate such as boehmite and diaspore (Al ₂ O ₃・ H ₂ O); gibsite. , Aluminum hydroxide [Al (OH) ₃ ] such as bayarite; 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), hydroxide calcium [Ca _(OH) 2], magnesium aluminum oxide _{(MgO · Al 2 O 3)} , clay _{(Al 2 O 3 · 2SiO 2} ), kaolin _{(Al 2 O 3 · 2SiO 2} · 2H 2 O), pyrophyllite _{(Al 2 O 3 · 4SiO 2} · H 2 O), bentonite _{(Al 2 O 3 · 4SiO 2} · 2H 2 O), aluminum silicate _{(Al 2 SiO 5, Al 4} · 3SiO 4 · 5H 2 O , etc.), Magnesium silicate (Mg ₂ SiO ₄ , MgSiO ₃ etc.), Calcium silicate (Ca ₂ · SiO ₄ etc.), Aluminium aluminum silicate (Al ₂ O ₃ · CaO · _{2SiO 2} etc.), Calcium magnesium silicate (CaMgSiO _{4 etc.)} ), Calcium carbonate (CaCO ₃ ), zirconium oxide (ZrO ₂ ), zirconium hydroxide [ZrO (OH) ₂ · nH ₂ O], zirconium carbonate [Zr (CO ₃ ) ₂ ], zinc acrylate, zinc methacrylate, Examples thereof include crystalline aluminosilicates containing hydrogen, alkali metals or alkaline earth metals that correct the charge like various zeolites. In these inorganic fillers, the surface of the inorganic filler may be organically treated in order to improve the affinity with the rubber component.

As the inorganic filler, silica is preferable from the viewpoint of imparting rubber strength, more preferably silica alone, or silica and one or more kinds of inorganic compounds usually used in the rubber industry can be used in combination. When the above-mentioned inorganic compound other than silica and silica is used in combination as the inorganic filler, it may be appropriately adjusted so that the total amount of all the components of the inorganic filler is within the above range.

Silica is preferably added because it can impart rubber strength. Any commercially available silica can be used. Among them, preferred silica is wet silica, dry silica, or colloidal silica, and more preferably wet silica. The surface of these silicas may be organically treated in order to improve the affinity with the rubber component.

The BET specific surface area of silica is not particularly limited, and examples thereof include a range of ^{40 to 350 m 2 / g.} Silica having a BET specific surface area in this range has an advantage that both rubber reinforcing property and dispersibility in a rubber component can be achieved at the same time. The BET specific surface area is measured according to ISO 5794/1.

From this point of view, the preferred silica is a silica having a BET specific surface area in ^{the range of 80 to 300 m 2} / g, more preferably a silica having a BET specific surface area of 100 to 270 m ² / g, and particularly preferably. , BET specific surface area is silica in the range of ^{110-270 m 2 / g.}

Commercially available products of such silica include trade names "HD165MP" (BET specific surface area = 165m ² / g) and "HD115MP" (BET specific surface area = 115m ² / g) manufactured by Quechen Silicon Chemical Co., Ltd. "HD200MP" (BET specific surface area = 200m ² / g), "HD250MP" (BET specific surface area = 250m ² / g), trade name "Nipseal AQ" manufactured by Toso Silica Co., Ltd. (BET specific surface area = 205m ² / g) ), "Nip seal KQ" (BET specific surface area = 240 m ² / g), product name "Ultra Jill VN3" manufactured by Degussa (BET specific surface area = 175 m ² / g), product name "Z1085 Gr" (BET) manufactured by Silica. Specific surface area = 90 m ² / g), "Z Premium ^{200MP" (BET specific surface area = 215 m 2} / g), "Z HRS 1200 MP" (BET specific surface area = 200 m ² / g) and the like.

The blending amount of silica is usually 20 to 150 parts by mass, preferably 30 to 120 parts by mass, and more preferably 40 to 90 parts by mass with respect to 100 parts by mass of the rubber component.

Usually, the addition of silica improves the steering stability performance, but the addition of a large amount tends to worsen the low heat generation. However, by using the dihydrotetrazine compound (1), excellent low heat generation is exhibited even if a large amount of silica is blended.

In particular, the amount of silica blended in order to achieve both steering stability performance and fuel efficiency is usually 40 to 120 parts by mass, preferably 60 to 115 parts by mass with respect to 100 parts by mass of the rubber component. More preferably, it is 70 to 110 parts by mass.

By blending the dihydrotetrazine compound (1) in the rubber composition containing an inorganic filler, particularly silica, the dispersibility of silica can be significantly improved, and the low heat generation property of the rubber composition can be remarkably improved.

Carbon black The carbon black is not particularly limited, and examples thereof include commercially available carbon black and Carbon-Silica Dual phase filler. By containing carbon black in the rubber component, it is possible to enjoy the effect of lowering the electric resistance of the rubber, suppressing the charge, and further improving the strength of the rubber.

Specifically, carbon black includes, for example, high, medium or low structure SAF, ISAF, IISAF, N110, N134, N220, N234, N330, N339, N375, N550, HAF, FEF, GPF, SRF grade carbon. Black and the like can be mentioned. Among them, preferable carbon blacks are SAF, ISAF, IISAF, N134, N234, N330, N339, N375, HAF, or FEF grade carbon black.

The DBP absorption of carbon black is not particularly limited, preferably 60~200cm ³ / 100g, more preferably 70~180cm ³ / 100g or more, particularly preferably 80~160cm ³ / 100g.

The nitrogen adsorption specific surface area of carbon black (measured according to N2SA, JIS K 6217-2: 2001) is preferably 30 to 200 m ² / g, more preferably 40 to 180 m ² / g, and particularly preferably. It is 50 to 160 m ² / g.

In the rubber composition containing carbon black, the tetrazine compound produced by oxidizing the dihydrotetrazine compound (1) or the reaction product of the rubber component and the dihydrotetrazine compound (1) strongly interact with carbon black. It is possible that it will act. Therefore, according to the rubber composition of the present invention, the dispersibility of carbon black is significantly improved, and the low heat generation property of the rubber composition can be remarkably improved.

Other Blending Agents In addition to the dihydrotetrazine compound (1), an oxidizing agent, and an inorganic filler and / or carbon black, the rubber composition of the present invention includes a compounding agent commonly used in the rubber industry, for example. , Sulfur and other vulcanizing agents can be blended. Further, the rubber composition of the present invention contains another compounding agent, for example, an antioxidant, an antioxidant, a softener, a processing aid, a wax, a resin, a foaming agent, an oil, stearic acid, and zinc oxide (ZnO). , Vulcanization accelerator, vulcanization retarder and the like may be blended. These compounding agents can be appropriately selected and compounded within a range that does not impair the object of the present invention. As these compounding agents, commercially available products can be preferably used.

Further, in a rubber composition containing an inorganic filler such as silica, silane coupling is used for the purpose of enhancing the reinforcing property of the rubber composition by silica, or for the purpose of enhancing the wear resistance as well as the low heat generation of the rubber composition. The agent may be blended.

The silane coupling agent that can be used in combination with the inorganic filler is not particularly limited, and a commercially available product can be preferably used. Examples of such a silane coupling agent include sulfide-based, polysulfide-based, thioester-based, thiol-based, olefin-based, epoxy-based, amino-based, and alkyl-based silane coupling agents.

Examples of the sulfide-based silane coupling agent include bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (3-methyldimethoxysilylpropyl) tetrasulfide, and bis ( 2-Triethoxysilylethyl) tetrasulfide, bis (3-triethoxysilylpropyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide, bis (3-methyldimethoxysilylpropyl) disulfide, bis (2-triethoxysilylpropyl) Ethyl) disulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (3-methyldimethoxysilylpropyl) trisulfide, bis (2-triethoxysilylethyl) trisulfide Sulfate, bis (3-monoethoxydimethylsilylpropyl) tetrasulfide, bis (3-monoethoxydimethylsilylpropyl) trisulfide, bis (3-monoethoxydimethylsilylpropyl) disulfide, bis (3-monomethoxydimethylsilylpropyl) Tetrasulfide, bis (3-monomethoxydimethylsilylpropyl) trisulfide, bis (3-monomethoxydimethylsilylpropyl) disulfide, bis (2-monoethoxydimethylsilylethyl) tetrasulfide, bis (2-monoethoxydimethylsilylethyl) ) Trisulfide, bis (2-monoethoxydimethylsilylethyl) disulfide and the like. Of these, bis (3-triethoxysilylpropyl) tetrasulfide is particularly preferable.

Examples of the thioester-based silane coupling agent include 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltriethoxysilane, and 3-lauroylthiopropyltriethoxysilane. , 2-Hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane, 3-hexanoylthiopropyltrimethoxysilane, 3-Octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2-octanoylthioethyltrimethoxysilane, 2 − Decanoylthioethyltrimethoxysilane, 2-lauroylthioethyltrimethoxysilane and the like can be mentioned.

Examples of the thiol-based silane coupling agent include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropylmethyldimethoxysilane.

Examples of the olefin-based silane coupling agent include dimethoxymethylvinylsilane, vinyltrimethoxysilane, dimethylethoxyvinylsilane, diethoxymethylvinylsilane, triethoxyvinylsilane, vinyltris (2-methoxyethoxy) silane, allyltrimethoxysilane, and allyltri. Ethoxysilane, p-styryltrimethoxysilane, 3- (methoxydimethoxydimethylsilyl) propyl acrylate, 3- (trimethoxysilyl) propyl acrylate, 3- [dimethoxy (methyl) silyl] propyl methacrylate, 3- (trimethoxysilyl) Examples thereof include propyl methacrylate, 3- [dimethoxy (methyl) silyl] propyl methacrylate, 3- (triethoxysilyl) propyl methacrylate, 3- [tris (trimethylsiloxy) silyl] propyl methacrylate and the like.

Examples of the epoxy-based silane coupling agent include 3-glycidyloxypropyl (dimethoxy) methylsilane, 3-glycidyloxypropyltrimethoxysilane, diethoxy (3-glycidyloxypropyl) methylsilane, and triethoxy (3-glycidyloxypropyl) silane. , 2- (3,4-epylcyclohexyl) ethyltrimethoxysilane and the like. Of these, 3-glycidyloxypropyltrimethoxysilane is preferable.

Examples of the amino-based silane coupling agent include N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, and 3-aminopropyl. Trimethoxysilane, 3-aminopropyltriethoxysilane, 3-ethoxysilyl-N- (1,3-dimethylbutylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N- (vinylbenzyl)- Examples thereof include 2-aminoethyl-3-aminopropyltrimethoxysilane. Of these, 3-aminopropyltriethoxysilane is preferable.

Examples of the alkyl-based silane coupling agent include methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, isobutyltrimethoxysilane, and isobutyltriethoxy. Examples thereof include silane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, cyclohexylmethyldimethoxysilane, n-octyltriethoxysilane, n-decyltrimethoxysilane and the like. Of these, methyltriethoxysilane is preferred.

Among these silane coupling agents, bis (3-triethoxysilylpropyl) tetrasulfide can be particularly preferably used.

In the present invention, one type of silane coupling agent may be used alone, or two or more types may be used in combination.

The blending amount of the silane coupling agent of the rubber composition of the present invention is preferably 0.1 to 20 parts by mass, and particularly preferably 3 to 15 parts by mass with respect to 100 parts by mass of the inorganic filler. If it is 0.1 part by mass or more, the effect of improving the low heat generation of the rubber composition can be more preferably exhibited, and if it is 20 parts by mass or less, the cost of the rubber composition is reduced and the economy is economical. Because it improves.

Method for Producing Rubber Composition The method for producing the rubber composition of the present invention is not particularly limited. The method for producing a rubber composition of the present invention includes, for example, a step (A) of kneading a rubber component, a dihydrotetrazine compound (1), an oxidizing agent, and a raw material component containing an inorganic filler and / or carbon black, and a step. The step (B) of kneading the mixture obtained in (A) and the vulcanizing agent is included.

Process (A)
Step (A) is a step of kneading a raw material component containing a rubber component, a dihydrotetrazine compound (1), an oxidizing agent, and an inorganic filler and / or carbon black, and is a step before blending a vulcanizing agent. It means that there is.

In the step (A), the above-mentioned other compounding agents and the like can be further added, if necessary.

Examples of the kneading method in the step (A) include a method of kneading a composition containing a rubber component, a dihydrotetrazine compound (1), an oxidizing agent, an inorganic filler and / or carbon black. In this kneading method, the entire amount of each component may be kneaded at one time, or each component may be divided and kneaded according to the purpose such as viscosity adjustment. Further, after kneading the rubber component with the inorganic filler and / or carbon black, the dihydrotetrazine compound (1) and the oxidizing agent are added and kneaded, or the rubber component, the dihydrotetrazine compound (1) and the oxidizing agent are added and kneaded. After kneading with, an inorganic filler and / or carbon black may be added and kneaded. The kneading operation may be repeated in order to uniformly disperse each component.

The temperature at which the rubber composition is mixed in the step (A) is not particularly limited, and for example, the temperature of the rubber composition is preferably 60 to 190 ° C, more preferably 80 to 175 ° C. , 100-170 ° C. is more preferable.

The mixing time in the step (A) is not particularly limited, and is preferably, for example, 10 seconds to 20 minutes, more preferably 30 seconds to 10 minutes, and further preferably 2 minutes to 7 minutes. preferable.

In the step (A), the blending amount of the dihydrotetrazine compound (1) is not particularly limited, and is, for example, 0.1 to 10 parts by mass, preferably 0.25 parts by mass with respect to 100 parts by mass of the rubber component. It is ~ 5 parts by mass, more preferably 0.5 to 2 parts by mass.

In the step (A), the amount of the oxidizing agent to be blended is not particularly limited, and is preferably 0.1 to 30 mol with respect to 1 mol of the dihydrotetrazine compound (1), and is preferably 0.3 to 20 mol. It is more preferably mol, and even more preferably 0.5-10 mol.

The blending amount of the inorganic filler in the step (A) is usually 20 to 150 parts by mass, preferably 30 to 120 parts by mass, and more preferably 40 to 90 parts by mass with respect to 100 parts by mass of the rubber component. Is.

The blending amount of carbon black in the step (A) is usually 2 to 150 parts by mass, preferably 4 to 120 parts by mass, and more preferably 6 to 100 parts by mass with respect to 100 parts by mass of the rubber component. is there.

In the step (A), the inorganic filler and / or carbon black is a total amount of both components, for example, 20 to 150 parts by mass with respect to 100 parts by mass of the rubber component. It may be adjusted appropriately within the range of the amount.

Further, as another kneading method in the step (A), there is a step (A-1) of kneading the rubber component, the dihydrotetrazine compound (1) and the oxidizing agent, and the mixture obtained in the step (A-1). A two-step kneading method including a step (A-2) of kneading the mixture with an inorganic filler and / or a raw material component containing carbon black can be mentioned.

In the step (A-1), as a method of kneading the rubber component, the dihydrotetrazine compound (1) and the oxidizing agent, when the rubber component is a solid, the rubber component, the dihydrotetrazine compound (1) and the oxidizing agent are oxidized. Method of kneading the agent (kneading method); When the rubber component is liquid (liquid), the solution or emulsion (suspension) of the rubber component is mixed with the dihydrotetrazine compound (1) and the oxidizing agent. (Liquid mixing method) and the like.

The kneading temperature is preferably 80 to 190 ° C, more preferably 90 to 160 ° C, and even more preferably 100 to 150 ° C. In the case of the liquid mixing method, the upper limit of the temperature of the liquid rubber composition is preferably 80 to 170 ° C., more preferably 90 to 160 ° C., and even more preferably 100 to 150 ° C.

The mixing time or kneading time is not particularly limited. For example, in the case of the kneading method, it is preferably 10 seconds to 20 minutes, more preferably 30 seconds to 10 minutes, and 60 seconds to 7 minutes. It is more preferable to have. In the case of the liquid mixing method, it is preferably 10 seconds to 60 minutes, more preferably 30 seconds to 40 minutes, and even more preferably 60 seconds to 30 minutes. After the mixing reaction by the liquid mixing method, for example, the solvent in the mixture can be blown off (removed) and the solid rubber composition can be recovered under reduced pressure.

The blending amount of the dihydrotetrazine compound (1) in the step (A-1) is not particularly limited, and is, for example, usually 0.1 to 10 parts by mass, preferably 0 with respect to 100 parts by mass of the rubber component. It is .25 to 5 parts by mass, more preferably 0.5 to 2 parts by mass.

The temperature at which the mixture obtained in step (A-1) in step (A-2) and the inorganic filler and / or carbon black are mixed is not particularly limited, and for example, the temperature of the mixture is 60 to 60 to. It is preferably 190 ° C., more preferably 80 to 175 ° C., and even more preferably 100 to 170 ° C.

The mixing time in the step (A-2) is not particularly limited, and is preferably, for example, 10 seconds to 20 minutes, more preferably 30 seconds to 10 minutes, and 2 minutes to 7 minutes. Is even more preferable.

The blending amount of the inorganic filler in the step (A-2) is usually 20 to 150 parts by mass, preferably 30 to 120 parts by mass, based on 100 parts by mass of the mixture obtained in the step (A-1). It is more preferably 40 to 90 parts by mass.

The blending amount of carbon black in the step (A-2) is usually 2 to 150 parts by mass, preferably 4 to 120 parts by mass with respect to 100 parts by mass of the mixture obtained in the step (A-1). Yes, more preferably 6 to 100 parts by mass.

In the step (A-2), the amount of the inorganic filler and / or carbon black is usually 20 to 20 to the total amount of both components, for example, with respect to 100 parts by mass of the mixture obtained in the step (A-1). It may be appropriately adjusted within the range of the above-mentioned blending amount of each component so as to be 150 parts by mass.

Process (B)
The step (B) is a step of mixing the mixture obtained in the step (A) and the vulcanizing agent, and means the final step of kneading.

In the step (B), a vulcanization accelerator or the like can be further added, if necessary.

The mixing (or kneading) temperature of the step is not particularly limited, and is, for example, preferably 60 to 140 ° C., more preferably 80 to 120 ° C., and even more preferably 90 to 120 ° C. ..

The mixing (or kneading) time is not particularly limited, and is preferably, for example, 10 seconds to 20 minutes, more preferably 30 seconds to 10 minutes, and even more preferably 60 seconds to 5 minutes. ..

When proceeding from the step (A) to the step (B), it is preferable to lower the temperature by 30 ° C. or more from the temperature after the completion of the step in the previous step before proceeding to the next step (B).

In the method for producing a rubber composition of the present invention, various compounding agents such as stearic acid, zinc oxide, a vulcanization accelerator, and an antiaging agent, which are usually blended in the rubber composition, are added as necessary in step (A). Alternatively, it can be added in step (B).

By the above steps (A) and (B), a mixture obtained by treating a diene rubber in a rubber component with a dihydrotetrazine compound (1) and an oxidizing agent, and an inorganic filler and / or carbon black are added. The rubber composition contained can be produced.

The rubber composition in the present invention is mixed or kneaded using a Banbury mixer, a roll, an intensive mixer, a kneader, a twin-screw extruder and the like. After that, it is extruded and processed in an extrusion process, and is molded as, for example, a tread member, a sidewall member, or the like. Subsequently, the raw tire is molded by pasting and molding on a tire molding machine by a usual method. The raw tire is heated and pressurized in a vulcanizer to obtain a tire.

2. Tire The tire of the present invention is a tire manufactured by using the rubber composition of the present invention.

Examples of the tire of the present invention include a pneumatic tire (radial tire, bias tire, etc.), a solid tire, and the like.

The use of the tire is not particularly limited, and examples thereof include a passenger car tire, a high load tire, a motorcycle (motorcycle) tire, a studless tire, and the like, and among them, the tire can be preferably used for a passenger car tire.

The shape, structure, size and material of the tire of the present invention are not particularly limited and may be appropriately selected depending on the intended purpose.

In the tire of the present invention, the rubber composition is used particularly for at least one member selected from a tread portion, a sidewall portion, a bead area portion, a belt portion, a carcass portion and a shoulder portion.

Among them, one of the preferred embodiments is to form the tire tread portion or sidewall portion of the pneumatic tire with the rubber composition.

The tread portion is a portion having a tread pattern and in direct contact with the road surface, and is a tire outer skin portion that protects the carcass and prevents wear and trauma, and is a cap tread and / or cap tread that constitutes the ground contact portion of the tire. A base tread that is placed inside.

The sidewall portion is, for example, a portion of a pneumatic radial tire from the lower side of the shoulder portion to the bead portion, which protects the carcass and is the portion that bends most when traveling.

The bead area is a part that fixes both ends of the carcass cord and at the same time fixes the tire to the rim. A bead is a structure in which high carbon steel is bundled.

The belt portion is a reinforcing band stretched in the circumferential direction between the tread having a radial structure and the carcass. The carcass is strongly tightened like a vat to increase the rigidity of the tread.

The carcass portion is a portion of the cord layer forming the skeleton of the tire, and plays a role of withstanding the load received by the tire, the impact, and the filling air pressure.

The shoulder part is the shoulder part of the tire and serves to protect the carcass.

The tire of the present invention can be manufactured according to a method known so far in the field of tires. Further, as the gas to be filled in the tire, normal or air with adjusted oxygen partial pressure; an inert gas such as nitrogen, argon or helium can be used.

Since the tire of the present invention has low heat generation and the rolling resistance of the tire is reduced, it is possible to reduce the fuel consumption of the automobile. Further, since a rubber composition highly filled with silica also exhibits high heat generation, it is possible to provide a fuel-efficient tire having high steering stability performance.

Hereinafter, the present invention will be specifically described with reference to Production Examples and Examples. However, the examples are merely examples, and the present invention is not limited to the examples.

Production Example 1: Production of compound (1a) of general formula (1) having ^{X 1} = X ² = 3-pyridyl group In a 500 mL four-necked flask, 78 g (0.75 mol) of 3-cyanopyridine, hydrated hydrazine. 49 g (1.3 eq) and 30 mL of methanol were added, and the mixture was stirred at 70 ° C. for 1 hour. Next, 270 mL of methanol and 7 g (10 mol%) of thioglycolic acid were added to this mixture, a reflux tube was attached, and the mixture was heated and stirred overnight at an outside temperature of 80 ° C. The reaction was hot filtered and washed with a small amount of cold methanol. Crude crystals and 300 mL of methanol were added to a 200 mL four-necked flask, and the mixture was heated and stirred at an outside temperature of 80 ° C. for 1 hour. The suspension was hot filtered, washed with a small amount of methanol and then dried under reduced pressure to give the title compound (1a) in 54 g of orange crystals.
Melting point: 229 ° C,
^{1 1} H-NMR (500 MHz, DMSO-d ₆ , δ ppm):
7.47-7.49 (m, 2H), 8.17 (d, J = 5.0, Hz, 2H), 8.65 (d, J = 5.0 Hz, 2H), 8,98 ( s, 2H), 9.32 (s, 2H)

Production Example 2: Production of compound (1b) of the general formula (1) having ^{X 1} = X ² = 2-pyridyl group In a 2 L four-necked flask, 420 g (4.0 mol) of 2-cyanopyridine and hydrated hydrazine. 260 g (1.0 eq) and 160 mL of methanol were added, and the mixture was stirred at 70 ° C. for 1 hour. Next, 640 mL of methanol and 37 g (10 mol%) of thioglycolic acid were added to this mixture, a reflux tube was attached, and the mixture was heated and stirred at an outside temperature of 80 ° C. for 4 hours. The reaction was filtered and washed with a small amount of cold methanol. Crude crystals and 640 mL of methanol were added to a 100 mL four-necked flask, and the mixture was heated and stirred at an outside temperature of 80 ° C. for 1 hour. The suspension was filtered, washed with a small amount of methanol and then dried under reduced pressure to give the title compound (1b) in 380 g of orange crystals.
Melting point: 196 ° C,
^{1 1} H-NMR (500 MHz, DMSO-d ₆ , δ ppm):
7.53 to 7.55 (m, 1H), 7.92 to 7.99 (m, 2H), 8.64 (d, J = 5.0 Hz, 1H), 8,98 (s, 1H)

Production Example 3: Production of compound (1c) of the general formula (1) having ^{X 1} = X ² = 4-pyridyl group In a 1 L four-necked flask, 104 g (1.0 mol) of 4-cyanopyridine and hydrated hydrazine. 65 g (1.0 eq), 9.8 g (0.1 eq) of thioglycolic acid and 600 mL of methanol were added, a reflux tube was attached, and the mixture was heated and stirred overnight at an outside temperature of 70 ° C. The reaction was ice-cooled, the crystals were filtered and washed with a small amount of cold methanol. Crude crystals and 500 mL of methanol were added to a 1 L four-necked flask, and the mixture was stirred at room temperature for 1 hour. The suspension was filtered, washed with a small amount of methanol and then dried under reduced pressure to give the title compound (1c) in 72 g of orange crystals.
Melting point: 267 ° C (decomposition),
^{1 1} H-NMR (300 MHz, DMSO-d ₆ , δ ppm):
7.75 to 7.77 (m, 2H), 8.67 to 8.79 (m, 2H), 9.43 (s, 1H)

Production Example 4: Production of compound (1d) of general formula (1) having ^{X 1} = X ² = 2-furanyl group In a 500 mL eggplant-shaped flask, 50 g (0.54 mol) of 2-fluoronitrile and 55 g of hydrated hydrazine (5 g). 2.0 equivalent) and 250 mL of ethanol were added, and the mixture was stirred under ice-cooling. Next, 5 g (10 mol%) of thioglycolic acid was added to this mixture, a reflux tube was attached, and the mixture was heated and stirred at an outside temperature of 85 ° C. for 2 hours. The reaction was ice-cooled, the crystals were filtered and washed with a small amount of cold ethanol. The crude crystals were dried under reduced pressure to obtain 47 g of brown dihydrotetrazine crude crystals. Crude crystals were added to a 2 L eggplant-shaped flask. Further, 1500 mL of THF was added, and the mixture was dissolved by irradiating the mixture with ultrasonic waves for 30 minutes in an ultrasonic bath, and the solution was ice-cooled. The precipitated white crystals were filtered through a membrane filter having a pore size of 0.2 μm, and the filtrate was concentrated. The concentrate was dissolved in 1500 mL of THF and ice-cooled. The precipitated white crystals were filtered and concentrated twice, and the title compound (1d) was obtained in 23 g of a light brown solid from the concentrate of the filtrate.
Melting point: 186 ° C (decomposition),
^{1 1} H-NMR (300 MHz, DMSO-d ₆ , δ ppm):
6.60 to 6.10 (m, 1H), 7.12 (d, J = 0.9, Hz, 1H), 7.81 (d, J = 0.6 Hz, 1H), 8.96 ( s, 1H)

Production Example 5: Production of compound (1e) of the general formula (1) having ^{X 1} = X ² = carboxyl group To a 3L four-necked flask, 300 g (2.2 mol) of glycine ethyl hydrochloride and 530 mL of water were added. , The solution temperature was −5 ° C., and the mixture was stirred. After replacing the inside of the container with nitrogen, a solution of 178 g (2.6 mol) of ice-cooled sodium nitrite in water (530 mL) was added dropwise to this solution. The solution temperature was cooled to −9 ° C., 200 mL of 5% sulfuric acid was added dropwise thereto, the solution temperature was maintained at −9 ° C., and the mixture was stirred for 10 minutes. The reaction solution was transferred to a separating funnel, and the lower layer was separated.

356 g (8.9 mol) of sodium hydroxide and 480 mL of water were added to a 2 L four-necked flask, and the mixture was heated to a solution temperature of 50 ° C. and stirred at the same temperature. The lower layer separated in the above step was added dropwise at a solution temperature of 50 to 70 ° C., and the mixture was stirred at 60 ° C. for 1 and a half hours. The reaction mixture was cooled to room temperature, poured into 2.2 L of ethanol, and cooled and stirred at a solution temperature of 0 ° C. The obtained reaction solution was allowed to stand, the supernatant was decanted, 1.1 L of ethanol was added, and stirring, standing, and decantation were repeated 5 times. The suspension was filtered and washed with 1 L of ethanol and 1 L of diethyl ether, and then dried under reduced pressure to obtain 167 g of a yellow dihydrotetrazine sodium salt solid.

To a 500 mL eggplant-shaped flask, 60 g of the obtained solid, 66 mL of water, and 66 g of crushed ice were added, and the mixture was stirred under ice-cooling. Then, 55.6 mL of concentrated hydrochloric acid was added dropwise to this mixture over 1 hour, and the mixture was stirred for 30 minutes. 100 mL of diethyl ether was added, and the mixture was allowed to stand, and the decantation of the supernatant was repeated 5 times. The suspension was filtered and washed with a small amount of diethyl ether and then dried under reduced pressure to give the title compound (1e) in 30 g of a yellow solid.
Melting point: 142-146 ° C,
^{1 1} H-NMR (500 MHz, DMSO-d ₆ , δ ppm): 7.36 (s, 2H), 8.29 (br, 2H)

Production Example 6: Production of compound (1f) of the general formula (1) having ^{X 1} = X ² = methoxycarbonyl group In a nitrogen atmosphere, 1350 mL of methanol was added to a 3 L four-necked flask, and the mixture was cooled and stirred at −30 ° C. 73.8 mL (1.0 mol) of thionyl chloride was added dropwise thereto, and the mixture was stirred at −30 ° C. for 30 minutes. After adding 87 g (0.5 mol) of the compound (1e) prepared in Production Example 5 over 30 minutes, the mixture was stirred at room temperature for 1 hour, 35 to 40 ° C. for 2 hours, and further at −30 ° C. for 1 hour. Stirred. The suspension was filtered and washed with 500 mL of diisopropyl ether. The obtained solid was dissolved in 4 L of dichloromethane, filtered, and the filtrate was concentrated under reduced pressure and dried under reduced pressure to obtain 46.6 g of the title compound (1f) as a yellow solid.
Melting point: 171-172 ° C,
^{1 1} H-NMR (500 MHz, CDCl ₃ , δ ppm): 7.46 (s, 2H), 3.93 (s, 6H)

Examples 1-7 and Comparative Examples 1-7
Each component shown in steps (A) of Tables 1 and 2 below was mixed at that ratio (part by mass), and kneaded with a Banbury mixer for 5 minutes while adjusting the rotation speed so that the maximum temperature of the mixture was 160 ° C. .. After curing until the temperature of the mixture becomes 80 ° C. or lower, each component shown in steps (B) of Tables 1 and 2 is added at the ratio (part by mass), and the maximum temperature of the mixture becomes 110 ° C. or lower. The rubber composition was produced by kneading while adjusting the above.

Examples 8-12 and Comparative Examples 8-10
Each rubber component, dihydrotetrazine compound and oxidizing agent shown in the step (A-1) of Table 3 below were kneaded at their ratios (parts by mass) using a Banbury mixer. From the time when the temperature of the mixture reached 130 to 180 ° C., the mixture was kneaded for about 2 minutes while adjusting to maintain the temperature, and then cooled with a roll mill to produce the mixture.

Each component shown in step (A-2) of Table 3 is mixed with the obtained mixture at the ratio (part by mass), and the rotation speed is adjusted so that the maximum temperature of the mixture becomes 160 ° C. with a Banbury mixer. Kneaded for 5 minutes. After curing until the temperature of the mixture becomes 80 ° C. or lower, each component shown in step (B) of Table 3 is added at that ratio (part by mass), and the maximum temperature of the mixture is adjusted to 110 ° C. or lower. While kneading, a rubber composition was produced.

Low heat buildup (tan δ index) The rubber compositions (test compositions) prepared in Examples 1 to 12 and Comparative Examples 1 to 10 were operated at a temperature of 40 ° C. using a viscoelasticity measuring device (manufactured by Metravib). Tan δ was measured at a strain of 5% and a frequency of 15 Hz.

The low exothermic index was calculated based on the following formula with reference to the rubber composition prepared in Comparative Example 1 or 8 to which the dihydrotetrazine compound (1) and the oxidizing agent were not added.

The larger the value of the low heat generation index, the lower the heat generation and the smaller the hysteresis loss. Further, the low heat generation property of the vulcanized rubber composition of each reference is set to 100.

The results are shown in Tables 1-3.
Formula: Low exothermic index = {(reference tan δ) / (test composition tan δ)} × 100

[Explanation of symbols in the table]
The raw materials used in the examples (in the table) are shown below.
* 1: Made by PetroChina Dushanzi Petrochemical Company, product name "RC2557S"
* 2: Product name "BR9000" manufactured by Sinopec Qilu Petrochemical Co., Ltd.
* 3: Product name "HD165MP" manufactured by Quechen Silicon Chemical Co., Ltd.
* 4: Product name "Si69" manufactured by Evonik Industries AG
* 5: Product name "Antilux 111" manufactured by Rhein Chemie Rheinau GmbH
* 6: Product name "Vivatec 700" manufactured by Hansen & Rosenthal
* 7: Made by Sichuan Tianyu Grease Chemical Co., Ltd. * 8: Made by Kemai Chemical Co., Ltd., Product name "6-PPD"
* 9: Made by Dalian Zinc Oxide Co., Ltd. * 10: Made by Kemai Chemical Co., Ltd., Product name "DPG"
* 11: Product name "CBS" manufactured by Kemai Chemical Co., Ltd.
* 12: Sulfur, manufactured by Shanghai Jinghai Chemical Co., Ltd. * 13: Compound manufactured in Production Example 1 * 14: Compound manufactured in Production Example 2 * 15: Compound manufactured in Production Example 3 * 16: Production Example 4 * 17: Compound described in Example 1 of Patent Document 6 * 18: Sodium nitrite, manufactured by Kokuan Group Chemical Testing Co., Ltd. * 19: 2,3-dichloro-5,6-dicyano-1, 4-Benzoquinone, manufactured by Tokyo Kasei Kogyo Co., Ltd. * 20: Iodobenzene diacetate, manufactured by Kokuan Group Chemical Testing Co., Ltd. * 21: N-bromosuccinimide, manufactured by Kokuan Group Chemical Testing Co., Ltd.

In the rubber composition of the present invention, the dispersibility of the inorganic filler (for example, silica, etc.) and / or carbon black is improved by blending the dihydrotetrazine compound (1) and the oxidizing agent, resulting in low heat generation. Are better. The rubber composition of the present invention is excellent in low heat generation even if a silane coupling agent is not added to the rubber composition. Therefore, it can be used as a member of various pneumatic tires of various automobiles, especially a tread member, a sidewall member, a bead area member, a belt member, a carcass member, and a shoulder member of a pneumatic radial tire. it can.

Claims (6)

A rubber composition containing a rubber component, a dihydrotetrazine compound represented by the following general formula (1) or a salt thereof, an oxidizing agent, and a carbon black and / or an inorganic filler.

Wherein, X ¹ and X ² are the same or different and represent a pyridyl group which may have a location substituent. ] The substituents are 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 and a hydroxyalkyl group. The rubber composition according to claim 1, wherein the rubber composition is at least one selected from the group consisting of a hydroxyl group, an alkoxy group, an aryl group, an aryloxy group, a heterocyclic group, a thiol group, an alkylthio group, and an arylthio group. The rubber composition according to claim 1 or 2, which is used for at least one member selected from a tread portion, a sidewall portion, a bead area portion, a belt portion, a carcass portion and a shoulder portion. A tire produced by using the rubber composition according to any one of claims 1 to 3. In the step (A) and the step (A) of mixing the rubber component, the dihydrotetrazine compound represented by the general formula (1) or a salt thereof, the oxidizing agent, and the raw material component containing the inorganic filler and / or carbon black. A method for producing a rubber composition, which comprises a step (B) of mixing the obtained mixture and a vulcanizing agent. The step (A) was obtained in the step (A-1) of mixing the rubber component, the dihydrotetrazine compound represented by the general formula (1) or a salt thereof, and the oxidizing agent, and the step (A-1). The production method according to claim 5, which is a step (A-2) of mixing the mixture and the inorganic filler and / or carbon black.