JP2018150438A - Rubber composition and tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition which can exhibit excellent bending resistance and low heat build-up properties.SOLUTION: The rubber composition contains: a rubber component; a tetrazine compound represented by general formula (1) [where Xand Xeach represent an optionally substituted heterocyclic group] or a salt thereof; and carbon black having a nitrogen adsorption specific surface area of 25-110 m/g. A natural rubber is contained in an amount of 30 pts.mass or more in 100 pts.mass of the rubber component. The rubber composition contains, based on 100 pts.mass of the rubber component, 0.1-10 pts.mass of the tetrazine compound or the salt thereof and 20-60 pts.mass of the carbon black.SELECTED DRAWING: None

Description

  The present invention relates to a rubber composition and a tire.

  In recent years, due to environmental considerations, carbon dioxide emission regulations have become stricter worldwide, and the demand for lower fuel consumption of automobiles has increased greatly. Low fuel consumption contributes greatly to the efficiency of the drive system and transmission system of engines, etc., but tire rolling resistance is also a major factor, and it is important to reduce rolling resistance to reduce fuel consumption of automobiles. . In addition, the sidewall portion of the tire needs to have not only low rolling resistance but also bend resistance.

  As a technique 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 with enhanced affinity for carbon black and silica as fillers (Patent Document 1); ) Rubber composition containing diene elastomer, inorganic filler as reinforcing filler, polysulfated alkoxysilane as coupling agent, 1,2-dihydropyridine, and 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).

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

  However, even when these rubber compositions of Patent Documents 1 to 5 are used, the improvement in low heat buildup is insufficient. Moreover, it has been inevitable that the bending resistance is lowered by improving the low heat build-up of the rubber composition.

  The demand for lower fuel consumption of automobiles is increasing further, and the development of tires that are extremely excellent in low heat generation is eagerly desired.

JP 2003-514079 A Special table 2003-523472 gazette JP2013-108004A JP 2000-169631 A JP 2005-220323 A

  An object of the present invention is to provide a rubber composition that can exhibit excellent bending resistance and low heat build-up.

  Another object of the present invention is to provide a tire excellent in both bending resistance and low heat build-up.

  As a result of intensive studies in order to solve the above problems, the present inventors have found that a carbon component having a specific nitrogen adsorption specific surface area is added to a rubber composition containing a natural rubber-containing rubber component and a tetrazine-based compound. It has been found that the above problems can be solved by adding a specific amount. As a result of further investigation based on such knowledge, the present inventors have completed the present invention.

The present invention provides the following rubber composition, tire and the like.
Item 1.
Rubber component, the following general formula (1):

[In formula, X < ¹ > and X < ² > show the heterocyclic group which may have a substituent. ]
A rubber composition containing a tetrazine compound represented by the formula (I) or a salt thereof, and carbon black having a nitrogen adsorption specific surface area of 25 to 110 m ² / g,
In 100 parts by mass of the rubber component, 30 parts by mass or more of natural rubber is included,
0.1 to 10 parts by mass of the tetrazine compound or a salt thereof and 20 to 60 parts by mass of the carbon black with respect to 100 parts by mass of the rubber component,
Rubber composition.
Item 2.
Item 2. The rubber composition according to Item 1, further comprising an inorganic filler.
Item 3.
Item 3. The rubber composition according to Item 2, wherein the inorganic filler is silica.
Item 4.
Item 4. The rubber composition according to Item 3, wherein the silica is wet silica having a BET specific surface area (m ² / g) in the range of 40 to 350.
Item 5.
Item 6. The rubber composition according to any one of Items 3 to 5, wherein the compounding amount of the inorganic filler is 20 to 150 parts by mass with respect to 100 parts by mass of the rubber composition.
Item 6.
Item 6. The rubber composition according to any one of Items 1 to 5, which is used for a sidewall portion.
Item 7.
Item 6. A tire sidewall produced using the rubber composition according to any one of Items 1 to 5.
Item 8.
A pneumatic tire using the tire sidewall according to Item 7.

  According to the present invention, by combining a specific rubber component, a tetrazine compound represented by the general formula (1) or a salt thereof, and carbon black having a specific nitrogen adsorption specific surface area, A rubber composition having excellent flex resistance can be provided.

  In addition, by producing a tire using the rubber composition of the present invention, not only can the rolling resistance of the tire be reduced and the heat generation property of the tire can be lowered, but also the bending resistance can be improved. Further, it is possible to provide a fuel-efficient tire excellent in bending resistance.

  The present invention is described in detail below.

1. Rubber composition The present invention is a rubber component, the following general formula (1):

[In formula, X < ¹ > and X < ² > show the heterocyclic group which may have a substituent. ]
Or a salt thereof (hereinafter sometimes referred to as “tetrazine compound (1)”) and carbon black having a nitrogen adsorption specific surface area of 25 to 110 m ² / g (hereinafter referred to as “carbon black”). A rubber composition comprising:
In 100 parts by mass of the rubber component, 30 parts by mass or more of natural rubber is included,
0.1 to 10 parts by mass of the tetrazine compound or a salt thereof and 20 to 60 parts by mass of the carbon black with respect to 100 parts by mass of the rubber component,
It is a rubber composition.

Rubber component The rubber component to be blended in the rubber composition of the present invention is not particularly limited, and examples thereof include natural rubber (NR), synthetic diene rubber, and a diene system such as a mixture of natural rubber and synthetic diene rubber. Examples thereof include rubber and non-diene rubbers other than these.

  Natural rubber includes natural rubber such as natural rubber latex, technical grade rubber (TSR), smoked sheet (RSS), gutta-percha, Tochu-derived natural rubber, guayule-derived natural rubber, Russian dandelion-derived natural rubber, and plant component fermented rubber. In addition, modified natural rubbers such as epoxidized natural rubber, methacrylic acid-modified natural rubber, and styrene-modified natural rubber can be mentioned.

  Synthetic diene rubbers include styrene-butadiene copolymer rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), nitrile rubber (acrylonitrile-butadiene copolymer rubber) (NBR), chloroprene rubber (CR). , Ethylene-propylene-diene terpolymer rubber (EPDM), styrene-isoprene-styrene terpolymer block copolymer (SIS), styrene-butadiene-styrene terpolymer copolymer block (SBS), and the like. Examples thereof include modified synthetic diene rubbers. Examples of the modified synthetic diene rubber include diene rubbers by a modification technique such as main chain modification, one-end modification, and both-end modification. Here, the modified functional group of the modified synthetic diene rubber includes at least one functional group containing a hetero atom such as an epoxy group, an amino group, an alkoxy group, a hydroxyl group, an alkoxysilyl group, a polyether group, or a carboxyl group. Things. Moreover, there is no restriction | limiting in particular about the ratio of cis / trans / vinyl of a diene part, It can use suitably in any ratio. The average molecular weight and molecular weight distribution of the diene rubber are not particularly limited, and an average molecular weight of 500 to 3 million can be suitably used. Moreover, there is no restriction | limiting in particular also about the manufacturing method of synthetic diene rubber, What was synthesize | combined by emulsion polymerization, solution polymerization, radical polymerization, anionic polymerization, cationic polymerization etc. is mentioned.

  The glass transition point of the diene rubber is effective in the range of −120 ° C. to −15 ° C. from the viewpoint of achieving both flexibility and low heat generation. The rubber composition of the present invention is preferably a diene rubber in which 50% by mass or more in the diene rubber has a glass transition point in the range of −70 ° C. to −20 ° C.

  Known non-diene rubbers can be widely used.

  The rubber component used in the rubber composition of the present invention must contain natural rubber from the viewpoint of low heat build-up. Specifically, it is preferable that 30 parts by mass or more of natural rubber is contained in 100 parts by mass of the rubber component, more preferably 70 parts by mass or more, and 80 to 100 parts by mass is blended. Particularly preferred.

  A rubber component can be used individually by 1 type or in mixture (blend) of 2 or more types. Among them, preferable rubber components are natural rubber, IR, SBR, BR or a mixture of two or more selected from these, more preferably natural rubber, SBR, BR or a mixture of two or more selected from these. . The blend ratio is not particularly limited, but it is preferable to blend SBR, BR or a mixture thereof in a ratio of 70 parts by mass or less in 100 parts by mass of the rubber component, and 30 parts by mass or less. It is more preferable. When blending a mixture of SBR and BR, the total amount of SBR and BR is preferably in the above range. Moreover, SBR at this time is 50-100 mass parts, and it is preferable that BR is the range of 0-50 mass parts.

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

[In formula, X < ¹ > and X < ² > show the heterocyclic group which may have a substituent. ]

  In the present specification, the “heterocyclic group” is not particularly limited, and examples thereof 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, 5-pyrimidyl group, 3-pyridyl group, 4-pyridazyl group, 4- (1,2,3-triazyl) group, 5- (1,2,3-triazyl) group, 2- (1,3,5- Triazyl) group, 3- (1,2,4-triazyl) group, 5- (1,2,4-triazyl) group, 6- (1,2,4-triazyl) group, 2-quinolyl group, 3- Quinolyl group, 4-quinolyl group, 5-quinolyl group, 6-quinolyl group, 7-quinolyl group, 8-quinolyl group, 1-isoquinolyl group, 3-isoquinolyl group, 4-isoquinolyl group, 5-isoquinolyl group, 6- Isoquinolyl group, 7-isoquinolyl group, 8-isoquinolyl group Ryl group, 2-quinoxalyl group, 3-quinoxalyl group, 5-quinoxalyl group, 6-quinoxalyl group, 7-quinoxalyl group, 8-quinoxalyl group, 3-cinnolyl group, 4-cinnolyl group, 5-cinnolyl group, 6- Cinnolyl group, 7-cinnolyl group, 8-cinnolyl group, 2-quinazolyl group, 4-quinazolyl group, 5-quinazolyl group, 6-quinazolyl group, 7-quinazolyl group, 8-quinazolyl group, 1-phthalazyl group, 4- Phthalazyl group, 5-phthalazyl group, 6-phthalazyl group, 7-phthalazyl group, 8-phthalazyl group, 1-tetrahydroquinolyl group, 2-tetrahydroquinolyl group, 3-tetrahydroquinolyl group, 4-tetrahydroquinolyl group 5-tetrahydroquinolyl group, 6-tetrahydroquinolyl group, 7-tetrahydroquinolyl group, 8-tetrahydro Noryl group, 1-pyrrolyl group, 2-pyrrolyl group, 3-pyrrolyl group, 2-furyl group, 3-furyl group, 2-thienyl group, 3-thienyl group, 1-imidazolyl group, 2-imidazolyl group, 4- Imidazolyl group, 5-imidazolyl group, 1-pyrazolyl group, 3-pyrazolyl group, 4-pyrazolyl group, 5-pyrazolyl group, 2-oxazolyl group, 4-oxazolyl group, 5-oxazolyl group, 2-thiazolyl group, 4- Thiazolyl group, 5-thiazolyl group, 3-isoxazolyl group, 4-isoxazolyl group, 5-isoxazolyl group, 3-isothiazolyl group, 4-isothiazolyl group, 5-isothiazolyl group, 4- (1,2,3-thiadiazolyl) group , 5- (1,2,3-thiadiazolyl) group, 3- (1,2,5-thiadiazole) group, 2- (1,3,4-thiadiazol) group 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, 2-indolyl group, 3-indolyl group, 4-indolyl group, 5-indolyl group, 6-indolyl group, 7 -Indolyl group, 1-isoindolyl group, 2-isoindole group Group, 3-isoindolyl group, 4-isoindolyl group, 5-isoindolyl group, 6-isoindolyl group, 7-isoindolyl group, 1-benzoimidazolyl group, 2-benzoimidazolyl group, 4-benzoimidazolyl group, 5-benzoimidazolyl group, 6-benzimidazolyl group Group, 7-benzimidazolyl group, 2-benzofuranyl group, 3-benzofuranyl group, 4-benzofuranyl group, 5-benzofuranyl group, 6-benzofuranyl group, 7-benzofuranyl group, 1-isobenzofuranyl group, 3-isobenzofuran Nyl group, 4-isobenzofuranyl group, 5-isobenzofuranyl group, 6-isobenzofuranyl group, 7-isobenzofuranyl group, 2-benzothienyl group, 3-benzothienyl group, 4-benzothienyl group, 5-benzothienyl group, 6-benzothienyl group 7-benzothienyl group, 2-benzoxazolyl group, 4-benzoxazolyl group, 5-benzoxazolyl group, 6-benzoxazolyl group, 7-benzoxazolyl group, 2-benzothiazolyl group 4-benzothiazolyl group, 5-benzothiazolyl group, 6-benzothiazolyl group, 7-benzothiazolyl group, 1-indazolyl group, 3-indazolyl group, 4-indazolyl group, 5-indazolyl group, 6-indazolyl group, 7-indazolyl group 2-morpholyl group, 3-morpholyl group, 4-morpholyl group, 1-piperazyl group, 2-piperazyl group, 1-piperidyl group, 2-piperidyl group, 3-piperidyl group, 4-piperidyl group, 2-tetrahydropyrani Group, 3-tetrahydropyranyl group, 4-tetrahydropyranyl group, 2-tetrahydrothiopyranyl Group, 3-tetrahydrothiopyranyl group, 4-tetrahydrothiopyranyl group, 1-pyrrolidyl group, 2-pyrrolidyl group, 3-pyrrolidyl group, 2-tetrahydrofuranyl group, 3-tetrahydrofuranyl group, 2-tetrahydrothienyl group , 3-tetrahydrothienyl group and the like. Among them, a preferable heterocyclic group is a pyridyl group, a furanyl group, a thienyl group, a pyrimidyl group or a pyrazyl group, and more preferably a pyridyl group.

  The heterocyclic group may have one or more substituents at substitutable positions. The substituent is not particularly limited, and examples thereof include halogen atoms, amino groups, aminoalkyl groups, alkoxycarbonyl groups, acyl groups, acyloxy groups, amide groups, carboxyl groups, carboxyalkyl groups, formyl groups, nitrile groups, nitro groups. 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 this specification, the “amino group” includes not only an amino group represented by —NH ₂ but also, for example, a methylamino group, an ethylamino group, an n-propylamino group, an isopropylamino group, 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 A linear or branched monoalkylamino group having 1 to 6 carbon atoms (particularly 1 to 4 carbon atoms) such as an amino group; 1 to 6 carbon atoms such as a dimethylamino group, an ethylmethylamino group or a diethylamino group (particularly A substituted amino group such as a dialkylamino group having two linear or branched alkyl groups having 1 to 4 carbon atoms is also included.

  In the present specification, the “aminoalkyl group” is not particularly limited, and examples thereof include aminoalkyl groups such as aminomethyl group, 2-aminoethyl group, and 3-aminopropyl group (preferably having 1 amino acid having an amino group). To 6 linear or branched alkyl groups).

  In the present specification, the “alkoxycarbonyl group” is not particularly limited, and examples thereof include a methoxycarbonyl group and an ethoxycarbonyl group.

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

  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 “amide group” is not particularly limited, and examples thereof include carboxylic acid amide groups such as acetamido group and benzamide group; thioamide groups such as thioacetamide group and thiobenzamide group; N-methylacetamide group, N -N-substituted amide groups such as benzylacetamide group; and the like.

  In the present specification, the “carboxyalkyl group” is not particularly limited, and examples thereof include 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. A carboxy-alkyl group such as -n-hexyl group (preferably an alkyl group having 1 to 6 carbon atoms having a carboxy group).

  In the present specification, the “hydroxyalkyl group” is not particularly limited, and examples thereof include hydroxy-alkyl groups such as hydroxymethyl group, hydroxyethyl group, hydroxy-n-propyl group, hydroxy-n-butyl group (preferably And an alkyl group having 1 to 6 carbon atoms having a hydroxy group).

  In the present specification, the “alkyl group” is not particularly limited and includes, for example, a linear, branched or cyclic alkyl group, and specifically includes, for example, a methyl group, an 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 A linear or branched alkyl group having 1 to 6 carbon atoms (particularly 1 to 4 carbon atoms), such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl, etc. Examples thereof include cyclic alkyl groups having 8 (particularly 3 to 6 carbon atoms).

  In the present specification, the “hydroxyalkyl group” is not particularly limited, and examples thereof include hydroxy-alkyl groups such as hydroxymethyl group, hydroxyethyl group, hydroxy-n-propyl group, hydroxy-n-butyl group (preferably And an alkyl group having 1 to 6 carbon atoms having a hydroxy group).

  In the present specification, the “alkoxy group” is not particularly limited and includes, for example, a linear, branched or cyclic alkoxy group, and specifically includes, for example, methoxy, ethoxy group, n-propoxy group. , Isopropoxy group, n-butoxy group, t-butoxy group, n-pentyloxy group, neopentyloxy group, n-hexyloxy group having 1 to 6 carbon atoms (particularly 1 to 4 carbon atoms), A branched alkoxy group; a cyclic group having 3 to 8 carbon atoms (particularly 3 to 6 carbon atoms) such as cyclopropyloxy group, cyclobutyloxy group, cyclopentyloxy group, cyclohexyloxy group, cycloheptyloxy group, cyclooctyloxy group, etc. An alkoxy group etc. are 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.

  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 includes, for example, a linear, branched or cyclic alkylthio group, and specifically includes, for example, a methylthio group, an ethylthio group, and an n-propylthio group. 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 A linear or branched alkylthio group having 1 to 6 carbon atoms (particularly 1 to 4 carbon atoms) such as a 3-methylpentylthio group; a cyclopropylthio group, a cyclobutylthio group, a cyclopentylthio group, a cyclohexylthio group Cyclic alkylthio groups having 3 to 8 carbon atoms (particularly 3 to 6 carbon atoms), such as a group, cycloheptylthio group, cyclooctylthio group, etc. And the like.

  In the present specification, the “arylthio group” is not particularly limited, and examples thereof include a phenylthio group, a biphenylthio group, and a naphthylthio group.

  The “salt” of the tetrazine 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 Examples include alkaline earth metal salts such as salts; quaternary ammonium salts such as dimethylammonium and triethylammonium.

In a preferred tetrazine compound (1), X ¹ and X ² are the same or different, and have a pyridyl group which may have a substituent, a furanyl group which may have a substituent, and a substituent. The compound may be a thienyl group which may be substituted, a pyrazolyl group which may have a substituent, a pyrimidyl group which may have a substituent, or a pyrazyl group which may have a substituent.

More preferable tetrazine compound (1) is that X ¹ and X ² are the same or different and each may have a 2-pyridyl group optionally having a substituent, a 3-pyridyl group optionally having a substituent, 4-pyridyl group which may have a group, 2-furanyl group which may have a substituent, thienyl group which may have a substituent, 1- which may have a substituent It is a compound that is a pyrazolyl group, a 2-pyrimidyl group that may have a substituent, or a 2-pyrazyl group that may have a substituent. Specifically, the compound may have a substituent. A 2-pyridyl group which may have a substituent, a 3-pyridyl group which may have a substituent, a 4-pyridyl group which may have a substituent, or a 2-furanyl group which may have a substituent. Compounds are particularly preferred.

Specific examples of the tetrazine compound (1) include
3,6-bis (2-pyridyl) -1,2,4,5-tetrazine,
3,6-bis (3-pyridyl) -1,2,4,5-tetrazine,
3,6-bis (4-pyridyl) -1,2,4,5-tetrazine,
3,6-bis (2-furanyl) -1,2,4,5-tetrazine,
3,6-bis (3,5-dimethyl-1-pyrazolyl) -1,2,4,5-tetrazine,
3,6-bis (2-thienyl) -1,2,4,5-tetrazine,
3-methyl-6- (2-pyridyl) -1,2,4,5-tetrazine,
3,6-bis (2-pyrimidinyl) -1,2,4,5-tetrazine,
3,6-bis (2-pyrazyl) -1,2,4,5-tetrazine and the like can be mentioned.

  Among these, preferred tetrazine compounds (1) are 3,6-bis (2-pyridyl) -1,2,4,5-tetrazine, 3,6-bis (3-pyridyl) -1,2,4,5- Tetrazine, 3,6-bis (2-furanyl) -1,2,4,5-tetrazine, and 3,6- (4-pyridyl) -1,2,4,5-tetrazine, more preferred tetrazine compounds (1) includes 3,6-bis (2-pyridyl) -1,2,4,5-tetrazine, 3,6-bis (3-pyridyl) -1,2,4,5-tetrazine, and 3, 6-bis (4-pyridyl) -1,2,4,5-tetrazine.

  From the viewpoint of imparting low rolling resistance to the rubber component, the amount of the tetrazine compound (1) is 0.1 to 10 parts by mass with respect to 100 parts by mass of the rubber component in the rubber composition. A preferable compounding amount of the tetrazine compound (1) is 0.25 to 5 parts by mass, and more preferably 0.5 to 2 parts by mass with respect to 100 parts by mass of the rubber component in the rubber composition.

  When the tetrazine compound (1) is a powder, the volume average diameter is not particularly limited. In light of low exothermic expression, 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 determined as a particle diameter corresponding to 50% of the integrated distribution curve from the volume standard particle size distribution using a particle size distribution measuring apparatus such as a laser light diffraction method.

  In addition, from the viewpoint of handling and ignitability or explosive risk reduction during handling, powder treated with oil, resin, stearic acid or the like may be used, or powder may be calcium carbonate, silica, etc. It may be used by mixing with other fillers.

Carbon Black Carbon black having a nitrogen adsorption specific surface area of 25 to 90 m ² / g is blended with the rubber composition of the present invention. Flexibility can be improved by including the carbon black in the rubber composition of the present invention.

The nitrogen adsorption specific surface area of carbon black is measured according to N2SA, JIS K 6217-2: 2001. The nitrogen adsorption specific surface area of carbon black is preferably 40 to 90 m ² / g, more preferably 50 to 85 m ² / g.

  Examples of such carbon black include commercially available carbon black and Carbon-Silica Dual phase filler.

  Specifically, as the carbon black, 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 etc. are mentioned. Among them, preferable carbon black is SAF, ISAF, IISAF, N134, N234, N330, N339, N375, HAF, or FEF grade carbon black.

There is no restriction | limiting in particular as DBP absorption amount of carbon black, Preferably it is 60-200 cm < ³ > / 100g, More preferably, it is 70-180 cm < ³ > / 100g or more, Most preferably, it is 80-160 cm < ³ > / 100g.

  In the rubber composition containing carbon black, the dispersibility of carbon black is greatly improved by adding the tetrazine compound (1), and the low heat build-up of the rubber composition can be remarkably improved.

  Carbon black is blended in an amount of 20 to 60 parts by mass with respect to 100 parts by mass of the rubber component. 20-50 mass parts is preferable with respect to 100 mass parts of rubber components, and, as for the compounding quantity of carbon black, 30-45 mass parts is more preferable.

  The rubber composition of the present invention preferably further contains an inorganic filler in addition to the rubber component, tetrazine compound (1), and carbon black.

  The compounding quantity of an inorganic filler is 20-80 mass parts normally with respect to 100 mass parts of rubber components, Preferably it is 25-60 mass parts, More preferably, it is 30-50 mass parts.

  In the rubber composition of the present invention, the carbon black and the inorganic filler are the total amount of both components, for example, usually 20 to 100 parts by mass, preferably 25 to 90 parts by mass with respect to 100 parts by mass of the rubber component. More preferably, it may be appropriately adjusted within the range of the above compounding amounts of the respective components so as to be 30 to 80 parts by mass.

  If the total amount of carbon black and inorganic filler is 30 parts by mass or more, it is preferable from the viewpoint of improving the reinforcing property of the rubber composition, and if it is 150 parts by mass or less, it is preferable from the viewpoint of reducing rolling resistance. In addition, when blending carbon black and an inorganic filler, a master batch polymer previously mixed with a polymer in a wet or dry manner may be used.

The inorganic filler is not particularly limited as long as it is an inorganic compound usually used in the rubber industry. Examples of inorganic compounds that can be used include alumina (Al ₂ O ₃ ) such as silica, 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 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), hydroxylated Calcium [Ca (OH) ₂ ], aluminum magnesium 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.) , Aluminum calcium silicate (Al ₂ O ₃ · CaO · 2SiO ₂ etc.), magnesium calcium silicate (CaMgSiO ₄ ), calcium carbonate (CaCO ₃ ), zirconium oxide (ZrO ₂ ), zirconium hydroxide [ZrO (OH) ₂ · _nH 2 O], zirconium carbonate _{[Zr (CO 3) 2]} , to correct the charge as various zeolites Hydrogen, crystalline aluminosilicates such as containing alkali metal or alkaline earth metal. In order to improve the affinity of the inorganic filler with the rubber component, the surface of the inorganic filler may be organically treated.

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

Among these, silica is preferable as the inorganic filler from the viewpoint of bending fatigue. There is no restriction | limiting in particular as a BET specific surface area of a silica, For example, the range of 40-350 m < ² > / g is mentioned. Silica having a BET specific surface area within this range has an advantage that both rubber reinforcement and dispersibility in the rubber component can be achieved. The BET specific surface area is measured according to ISO 5794/1.

From this viewpoint, the preferred silica is silica having a BET specific surface area in the range of 50 to 250 m ² / g, more preferably silica having a BET specific surface area of 100 to 230 m ² / g, particularly preferably. Silica having a BET specific surface area in the range of 110 to 210 m ² / g.

As commercial products of such silica, trade names “HD165MP” (BET specific surface area = 165 m ² / g), “HD115MP” (BET specific surface area = 115 m 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), Tosoh silica K.K. "Nipsil AQ" (BET specific surface area = 205m ² / g ), “Nip seal KQ” (BET specific surface area = 240 m ² / g), trade name “Ultrazil VN3” (BET specific surface area = 175 m ² / g) manufactured by Degussa, product name “Z1085Gr” (BET manufactured by Solvay) specific surface area = ^90m 2 / g), "Z Premium200MP" (BET specific surface area = 215m ² / g), "Z H S 1200MP "(BET specific surface area = 200m ² / g), and the like.

  As a compounding quantity of a silica, it is 20-120 mass parts normally with respect to 100 mass parts of rubber components, Preferably it is 30-100 mass parts, More preferably, it is 40-90 mass parts.

Other compounding agents In addition to the tetrazine compound (1), carbon black, and inorganic filler, the rubber composition of the present invention contains compounding agents commonly used in the rubber industry, such as sulfur additives. A sulfurizing agent can be blended. The rubber composition of the present invention further includes other compounding agents such as anti-aging agent, anti-ozone agent, softener, processing aid, wax, resin, foaming agent, oil, stearic acid, zinc white (ZnO). Further, a vulcanization accelerator, a vulcanization retarder and the like may be blended. These compounding agents can be appropriately selected and blended within a range that does not impair the object of the present invention. As these compounding agents, commercially available products can be suitably used.

  In addition, in a rubber composition in which an inorganic filler such as silica is blended, for the purpose of enhancing the reinforcing property of the rubber composition with silica, or for the purpose of enhancing the wear resistance as well as the low heat generation property of the rubber composition, An agent may be blended. It does not restrict | limit especially as a silane coupling agent which can be used together with an inorganic filler, A commercial item can be used conveniently. Examples of such silane coupling agents include sulfide-based, polysulfide-based, thioester-based, thiol-based, olefin-based, epoxy-based, amino-based, and alkyl-based silane coupling agents.

  Examples of sulfide-based silane coupling agents 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-triethoxysilyl) Ethyl) disulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (3-methyldimethoxysilylpropyl) trisulfide, bis (2-to Ethoxysilylethyl) trisulfide, bis (3-monoethoxydimethylsilylpropyl) tetrasulfide, bis (3-monoethoxydimethylsilylpropyl) trisulfide, bis (3-monoethoxydimethylsilylpropyl) disulfide, bis (3-mono Methoxydimethylsilylpropyl) 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 preferred.

  Examples of thioester-based silane coupling agents 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-octa Ylthio ethyltrimethoxysilane, 2- deca Neu thio ethyltrimethoxysilane, and 2-lauroyl thio ethyl trimethoxysilane.

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

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

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

  Examples of amino silane coupling agents 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 include 2-aminoethyl-3-aminopropyltrimethoxysilane. Of these, 3-aminopropyltriethoxysilane is preferred.

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

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

  In this invention, a silane coupling agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  0.1-20 mass parts is preferable with respect to 100 mass parts of inorganic fillers, and, as for the compounding quantity of the silane coupling agent of the rubber composition of this invention, it is especially preferable that it is 3-15 mass parts. If it is 0.1 part by mass or more, the effect of low exothermic property of the rubber composition can be expressed more suitably, and if it is 20 parts by mass or less, the cost of the rubber composition is reduced and economic efficiency is improved. Because it does.

  In cases where the braking characteristics are particularly important, a resin or the like may be added. Specific examples include natural resins such as rosin resins and terpene resins, resins such as petroleum resins, phenol resins, coal resins, and xylene resins. Examples of rosin resins include gum rosin, tall oil rosin, wood rosin, hydrogenated rosin, disproportionated rosin, polymerized rosin, modified rosin glycerin, pentaerythritol ester, and terpene resin as α-pinene resin. And terpene resins such as β-pinene and dipentene, aromatic modified terpene resins, terpene phenol resins, and hydrogenated terpene resins.

  In cases where processability is important, mineral oil, petrolatum, paraffin wax, petroleum resin, fatty acid, fatty acid ester, fatty alcohol, metal soap, fatty acid amide, phenol resin, polyethylene, polybutene, peptizer, Processing aids such as regenerative agents and organosiloxanes can be mentioned.

  Oil or the like may be added for adjusting the hardness. Process oils, vegetable oils or mixtures thereof can be used. As the process oil, for example, a paraffin process oil, an aroma process oil, a naphthenic process oil, or the like can be used. Vegetable oils include castor oil, cottonseed oil, sesame oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut oil, rosin, pine oil, pineapple, tall oil, corn oil, rice bran oil, beet flower oil, sesame oil, Examples include olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. Among these, paraffinic process oils and aroma based process oils are preferably used because they are advantageous in processability.

Use of rubber composition The use of the rubber composition of the present invention is not particularly limited, and examples thereof include a rubber part of a tire. Among them, a preferable use is a tire sidewall.

Production method of rubber composition The production method of 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 (I) of kneading a rubber component, a tetrazine compound (1), carbon black, and a raw material component containing an inorganic filler as necessary, and a step (I). And the step (II) of kneading the vulcanizing agent.

Step (I)
Step (I) is a step of kneading a rubber component, a tetrazine compound (1), carbon black, and a raw material component containing an inorganic filler as necessary, and is a step before blending a vulcanizing agent. I mean.

  In step (I), the above-mentioned other compounding agents and the like can be further blended as necessary.

  Examples of the kneading method in step (I) include a method of kneading a composition containing a rubber component, a tetrazine compound (1), carbon black, and, if necessary, an inorganic filler. In this kneading method, the entire amount of each component may be kneaded at a time, or each component may be dividedly added and kneaded according to the purpose such as viscosity adjustment. Alternatively, after kneading the rubber component and carbon black, the tetrazine compound (1) is added and kneaded, or after kneading the rubber component and tetrazine compound (1), the carbon black is added and kneaded. Good. Step (I) may be repeatedly kneaded a plurality of times. When blending an inorganic filler, the inorganic filler can be added together with carbon black and kneaded.

  There is no restriction | limiting in particular as temperature at the time of mixing the rubber composition in process (I), For example, it is preferable that the upper limit of the temperature of a rubber composition is 120-190 degreeC, and it is 130-175 degreeC. More preferably, it is 140-170 degreeC.

  The mixing time in step (I) 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 (I), the tetrazine compound (1) is blended in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of the rubber component. As a compounding quantity of a tetrazine compound (1), 0.25-5 mass parts is preferable with respect to 100 mass parts of rubber components, and 0.5-2 mass parts is more preferable.

  In the step (I), the carbon black is mixed in an amount of 20 to 60 parts by mass with respect to 100 parts by mass of the rubber component. As a compounding quantity of carbon black, 25-55 mass parts is preferable with respect to 100 mass parts of rubber components, and 30-50 mass parts is more preferable.

  When the inorganic filler is included, the blending amount of the inorganic filler in the step (I) is usually 20 to 150 parts by mass, preferably 30 to 120 parts by mass with respect to 100 parts by mass of the rubber component. Preferably it is 40-90 mass parts.

  In the step (I), the carbon black and the inorganic filler are the total amount of both components, for example, 30 to 150 parts by mass with respect to 100 parts by mass of the rubber component. What is necessary is just to adjust suitably within the range.

  Moreover, as another kneading method in the step (I), the step (I-1) of kneading the rubber component and the tetrazine compound (1), and the mixture (modified polymer) obtained in the step (I-1) A two-stage kneading method including a step (I-2) of kneading carbon black and an inorganic filler as necessary can be mentioned.

  In the step (I-1), as a method for kneading the rubber component and the tetrazine compound (1), when the rubber component is solid, a method for kneading the rubber component and the tetrazine compound (1) (kneading method). When the rubber component is liquid (liquid), a method of mixing the solution or emulsion (suspension) of the rubber component with the tetrazine compound (1) (liquid mixing method) may be used.

  The kneading temperature is not particularly limited. For example, in the case of the kneading method, the upper limit of the temperature of the rubber component is preferably 80 to 190 ° C, more preferably 90 to 160 ° C, and more preferably 100 to More preferably, it is 150 degreeC. In the case of the liquid mixing method, the upper limit of the temperature of the rubber component is preferably 80 to 170 ° C, more preferably 90 to 160 ° C, and further 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. More preferably it is. In the case of the liquid mixing method, the time is preferably 10 seconds to 60 minutes, more preferably 30 seconds to 40 minutes, and further preferably 60 seconds to 30 minutes. After the mixing reaction by the liquid mixing method, for example, the solvent in the mixture can be removed (removed) under reduced pressure, and the solid rubber composition can be recovered.

  In the step (I-1), the tetrazine compound (1) is blended in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of the rubber component. As a compounding quantity of a tetrazine compound (1), 0.25-5 mass parts is preferable with respect to 100 mass parts of rubber components, and 0.5-2 mass parts is more preferable.

  In the step (I-1) of kneading the rubber component and the tetrazine compound (1), the double bond of the diene rubber in the rubber component reacts with the tetrazine compound (1) to form a modified polymer.

  There is no restriction | limiting in particular as temperature at the time of mixing the mixture (modified | denatured polymer) obtained by process (I-1), carbon black, and an inorganic filler in process (I-2), For example, the temperature of a mixture Is preferably 120 to 190 ° C, more preferably 130 to 175 ° C, and still more preferably 140 to 170 ° C.

  The mixing time in step (I-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 more preferable.

  The compounding amount of carbon black in the step (I-2) is 20 to 60 parts by mass with respect to 100 parts by mass of the mixture (modified polymer) obtained in the step (I-1). As a compounding quantity of carbon black, 20-50 mass parts is preferable with respect to 100 mass parts of mixtures (modified | denatured polymer) obtained at the process (I-1), and 30-45 mass parts is more preferable.

  When blending the inorganic filler in the step (I-2), the blending amount is usually 20 to 150 parts by mass with respect to 100 parts by mass of the mixture (modified polymer) obtained in the step (I-1). Yes, preferably 30-120 parts by mass, more preferably 40-90 parts by mass.

  In addition, when mix | blending an inorganic filler in process (I-2), carbon black and an inorganic filler are the total amount of both components, for example, the mixture (modified polymer) 100 obtained by process (I-1). What is necessary is just to adjust suitably within the range of the said compounding quantity of each component so that it may become 20-150 mass parts normally with respect to a mass part.

  Through the step (I), the double bond part of the rubber component (diene rubber) and the tetrazine compound (1) react to form a modified polymer, and carbon black and, in some cases, the inorganic filler are suitably dispersed. A mixture can be obtained.

Step (II)
Step (II) is a step of mixing the mixture obtained in step (I) and the vulcanizing agent, and means the final stage of kneading.

  In step (II), a vulcanization accelerator and the like can be further blended as necessary.

  There is no restriction | limiting in particular as mixing (or kneading | mixing) temperature of process (II), For example, it is preferable that it is 60-140 degreeC, it is more preferable that it is 80-120 degreeC, and it is 90-120 degreeC. Further preferred.

  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 further preferably 60 seconds to 5 minutes. .

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

  In the method for producing a rubber composition of the present invention, various compounding agents such as a vulcanization accelerator such as stearic acid and zinc white, an anti-aging agent and the like, which are usually compounded in the rubber composition, are optionally added to the step (I Or in step (II).

  A rubber containing a modified polymer obtained by treating the diene rubber in the rubber component with the tetrazine compound (1) by the steps (I) and (II), carbon black, and, if necessary, an inorganic filler. A composition can be produced.

  The rubber composition of the present invention includes a rubber component, a tetrazine compound (1), carbon black, and a composition in which an inorganic filler is blended if necessary, and a diene rubber in the rubber component and a tetrazine compound (1 ), And a rubber composition containing carbon black and, if necessary, an inorganic filler.

  The modified polymer formed in the step (I) or (I-1) is produced by a reaction as shown in the following reaction formulas -1 to 4.

[Wherein, X ¹ and X ² are the same as above. ]

  In the reaction formula-1, the reverse electron request type Aza-Diels-Alder reaction between the double bond site of the diene rubber represented by the formula (A-1) and the tetrazine compound (1) gives a formula (B-1 The bicyclo ring structure represented by this is formed. The -N = N- moiety in this bicyclo ring structure is easily denitrogenated and has a six-membered ring structure represented by the formula (C-1), (C-2) or (C-3). A modified polymer is formed which has a six-membered ring structure represented by the formula (2-1) by being further oxidized by oxygen in the air.

[Wherein, X ¹ and X ² are the same as above. ]

  In Reaction Formula-2, similarly to Reaction Formula-1, from the double bond site of the diene rubber represented by Formula (A-2) and the tetrazine compound (1), Formula (B-2) or ( B-2 ′) and then a six-membered ring structure represented by formulas (C-4) to (C-9), and then formula (2-2) or (2-3) A modified polymer having a six-membered ring structure represented by

[Wherein, X ¹ and X ² are the same as above. R represents an alkyl group or a halogen atom. ]

  In the reaction formula-3, a reverse electron request type Aza-Diels-Alder reaction between the double bond site of the diene rubber represented by the formula (A-3) and the tetrazine compound (1) gives a formula (B-3 Or a modified polymer having a six-membered ring structure represented by formulas (2-4) to (2-7) by denitrogenation after forming a bicyclo ring structure represented by (B-3 ′) Manufactured. In addition, when R on the double bond site of the diene rubber represented by the formula (A-3) is a halogen atom, the elimination of the halogen atom may occur. A modified polymer having a six-membered ring structure represented by (2-1) is produced.

[Wherein, X ¹ , X ² and R are the same as above. ]

  In the reaction formula-4, similarly to the reaction of the reaction formula-3, the reaction between the double bond site of the diene rubber represented by the formula (A-4) and the tetrazine compound (1) gives a formula (B- 4) or after forming a bicyclo ring structure represented by (B-4 ′), a modified polymer having a six-membered ring structure represented by formulas (2-8) to (2-11) is produced. The

  As described above, the produced modified polymer has heteroatoms such as nitrogen atoms, and since these heteroatoms strongly interact with the inorganic filler (particularly silica) and carbon black, the rubber composition It is possible to enhance the dispersibility therein and to impart high low heat buildup and bending resistance.

  The rubber composition of the present invention is a modified polymer produced by a reaction between a rubber component, particularly a double bond of a diene rubber and a tetrazine compound (1), preferably the following formulas (2-1) to ( And a rubber composition containing a modified polymer having at least one selected from the compound structures represented by 2-11).

[Wherein, X ¹ , X ² and R are the same as defined above. ]

3. Tire The tire of the present invention is a tire produced using the rubber composition of the present invention.

  Examples of the tire of the present invention include tires such as pneumatic tires (radial tires, bias tires, etc.) and solid tires.

  There is no restriction | limiting in particular as a use of a tire, For example, the tire for passenger cars, the tire for heavy loads, the tire for motorcycles (motorcycle), a studless tire, etc. are mentioned, Especially, it can use suitably for a tire for passenger cars.

  There is no restriction | limiting in particular as a shape of a tire of this invention, a structure, a magnitude | size, and a material, According to the objective, it can select suitably.

  In the tire of the present invention, the rubber composition is particularly 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.

  Especially, it is mentioned as one of the preferable aspects that the sidewall part of a pneumatic tire is formed with the said rubber composition.

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

  The sidewall portion is, for example, a portion from the lower side of the shoulder portion to the bead portion in the pneumatic radial tire, and is the portion that is most bent when traveling while protecting the carcass.

  The bead area portion is a portion having a function of fixing both ends of the carcass cord and simultaneously fixing 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 a tread having a radial structure and the carcass. The carcass is tightened like a heel and the rigidity of the tread is increased.

  The carcass portion is a portion of the cord layer that forms the skeleton of the tire, and plays a role of withstanding the load, impact, and filling air pressure that the tire receives.

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

  The tire of the present invention can be produced according to a method known so far in the field of tires.

  Moreover, as gas with which a tire is filled, normal or adjusted oxygen partial pressure air; an inert gas such as nitrogen, argon, or helium can be used.

  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 3,6-bis (3-pyridyl) -1,2,4,5-tetrazine (1a) In a 200 mL four-necked flask, 24 g (0.23 mol) of 3-cyanopyridine, hydrated Hydrazine (15 g, 1.3 equivalents) and methanol (48 mL) were added, and the mixture was stirred at room temperature. Next, 3.6 g (15% by weight) of sulfur was added to this mixture, and a reflux tube was attached, followed by heating and stirring at an external temperature of 70 ° C. overnight. The reaction solution was ice-cooled, and the crystals were filtered and washed with a small amount of cold methanol. The crude crystals were dried under reduced pressure to obtain 19 g of orange dihydrotetrazine crude crystals.

17.8 g of the obtained crude crystals were dissolved in 178 g (40 equivalents) of acetic acid, and sulfur was removed by filtration. A dihydrotetrazine acetic acid solution and 178 mL of distilled water were added to a 1 L four-necked eggplant flask and stirred under ice cooling. 15.5 g (3 equivalents) of sodium nitrite was dissolved in 35 mL of distilled water, added dropwise to the reaction solution over about 1 hour, and stirred overnight at room temperature. The precipitated crystals were filtered and the crystals were neutralized with 10% multilayer water to obtain crude crystals. The crude crystals were purified with a silica gel column (ethyl acetate) to obtain 8.4 g (red purple, needle-like crystals) of the title tetrazine compound (1a).
Melting point: 200 ° C.
¹ H-NMR (300 MHz, CDCl ₃ , δ ppm):
7.59 (ddd, J = 0.9, 5.1, 7.8 Hz, 2H), 8.89-8.96 (m, 4H), 9.88 (dd, J = 0.9, 2 .4Hz, 2H)

Examples 1-4 and Comparative Examples 1-7
Each component described in the step (I) of the following Tables 1 and 2 was mixed in the ratio (parts by mass), and kneaded for 5 minutes with a Banbury mixer while adjusting the rotation speed so that the maximum temperature of the mixture was 160 ° C. . After curing until the temperature of the mixture reaches 80 ° C. or lower, each component described in Step (II) of Tables 1 and 2 is added in the proportion (part by mass), and the maximum temperature of the mixture becomes 110 ° C. or lower. Each rubber composition was manufactured by kneading while adjusting as described above.

Bending fatigue resistance test
About the rubber composition (test composition) produced in Examples 1-4 and Comparative Examples 1-7, based on JISK6251, it uses a JIS No. 3 dumbbell-shaped sample, and repeats distortion at a distortion rate of 60%. And the number of times until breakage was measured.

  Using the rubber composition produced in Comparative Example 1 as a reference, a bending fatigue resistance index was calculated based on the following formula. The larger the index, the better the bending fatigue resistance.

  The results are shown in Tables 1 and 2.

formula:
Bending fatigue resistance index = {(number of fractures of test composition) / (number of fractures of reference)} × 100

For the rubber compositions (test compositions) produced in the low exothermic (tan δ index) test examples 1 to 4 and comparative examples 1 to 7, a viscoelasticity measuring device (manufactured by Metravib) was used, and the temperature was 40 ° C. Tan δ was measured at a strain of 5% and a frequency of 15 Hz.

  Using the rubber composition produced in Comparative Example 1 as a reference, a low exothermic index was calculated based on the following formula.

  In addition, it shows that it is low exothermic property and a hysteresis loss is so small that the value of a low exothermic index is large. The low exothermic property of the reference vulcanized rubber composition is 100.

  The results are shown in Tables 1 and 2.

formula:
Low exothermic index = {(reference tan δ) / (tan δ of test composition)} × 100

[Explanation of symbols in the table]
The raw materials used in Tables 1 and 2 are shown below.
* 1: Product name “BR150B” manufactured by Ube Industries, Ltd.
* 2: Product name “RSS # 3”, manufactured by Chuka International Co., Ltd.
* 3: Tokai Carbon Co., Ltd., trade name “SEAST 3” (nitrogen adsorption specific surface area 79 m ² / g)
* 4: Tokai Carbon Co., Ltd., trade name “SEAST 9” (nitrogen adsorption specific surface area 142 m ² / g)
* 5: Tokai Carbon Co., Ltd., trade name “SEAST TA” (nitrogen adsorption specific surface area 19 m ² / g)
* 6: Product name “Antage 6C” manufactured by Kawaguchi Chemical Co., Ltd.
* 7: Zinc oxide brand "1 type" manufactured by Sakai Chemical Industry Co., Ltd.
* 8: Made by Sichuan Tianyu Grease Chemical Co., Ltd. * 9: Made by Nippon Seiwa Co., Ltd., trade name “OZOACE-0355”
* 10: Product name “X-140 (Aroma Oil)” manufactured by JX Nippon Oil & Energy Corporation
* 11: 3,6-bis (3-pyridyl) -1,2,4,5-tetrazine, compound prepared in Production Example 1 * 12: 3,6-bis (2-pyridyl) -1,2,4 , 5-tetrazine, manufactured by Tokyo Chemical Industry Co., Ltd. * 13: 3,6-bis (4-pyridyl) -1,2,4,5-tetrazine, manufactured by Tokyo Chemical Industry Co., Ltd. * 14: manufactured by Hosoi Chemical Co., Ltd. , Product name "HK200-5"
* 15: Ouchi Shinsei Chemical Co., Ltd., trade name "Noxeller CZ-G"
* 16: Product name “CTP”, manufactured by Ouchi Shinsei Chemical Co., Ltd.

  Since the rubber composition of the present invention is excellent in bending resistance and low heat build-up, the use of the rubber composition makes it possible to produce sidewall portions of various automobile pneumatic tires.

Claims (3)

Rubber component, the following general formula (1):

[In formula, X < ¹ > and X < ² > show the heterocyclic group which may have a substituent. ]
A rubber composition containing a tetrazine compound represented by the formula (I) or a salt thereof, and carbon black having a nitrogen adsorption specific surface area of 25 to 110 m ² / g,
In 100 parts by mass of the rubber component, 30 parts by mass or more of natural rubber is included,
0.1 to 10 parts by mass of the tetrazine compound or a salt thereof and 20 to 60 parts by mass of the carbon black with respect to 100 parts by mass of the rubber component,
Rubber composition. A tire sidewall produced using the rubber composition according to claim 1. A pneumatic tire using the tire sidewall according to claim 2.