JPWO2018169064A1 - Rubber composition for tires for icy roads and studless tires - Google Patents

Abstract

Diene rubber and the following general formula (1): [wherein X1 and X2 represent a heterocyclic group which may have a substituent. ] A rubber composition for tires for ice and snow roads containing a tetrazine compound or a salt thereof represented by the formula: , Rubber composition.

Description

  The present invention relates to a rubber composition for a tire for icy and snowy roads and a studless tire.

  From the viewpoint of improving the safety of vehicles, there is a demand for improving tire performance not only on dry road surfaces but also on various road surfaces such as wet road surfaces and ice and snow road surfaces.

For example, rubber compositions described in Patent Documents 1 to 3 have been proposed in order to improve steering stability (snow performance) on ice and snow road surfaces. Patent Document 1 discloses that a specific amount of a diene rubber mainly composed of natural rubber and / or butadiene rubber, carbon black and silica having a nitrogen adsorption specific surface area of 90 m ² / g or more, and ultra-high molecular weight polyethylene are blended. A rubber composition is described. Patent Document 2 discloses a rubber composition containing a specific amount of a rubber component containing 50% by mass or more of natural rubber, a thermoplastic resin, a filler containing silica, a vulcanization accelerator, a silane coupling agent, and a vulcanizing agent. Has been described. Patent Document 3 discloses that a specific amount of a myrcene resin, silica having a nitrogen adsorption specific surface area of 40 to 400 m ² / g or more, and a silica coupling agent are kneaded, and the obtained master batch is kneaded with a rubber component. The resulting rubber composition is described.

  According to the inventions described in Patent Documents 1 to 3, the snow performance of the rubber composition can be improved, and as a result, a tire having excellent snow performance can be obtained.

  However, these rubber compositions of Patent Documents 1 to 5 have insufficient effect of reducing the heat generation of the tire.

Japanese Patent Application Laid-Open No. 2006-241338 Japanese Patent Publication No. 2006-222871 JP-A-2006-3266

  An object of the present invention is to provide a rubber composition for a tire for icy and snowy roads that can exhibit excellent low heat build-up while maintaining snow performance.

  Another object of the present invention is to provide a studless tire which maintains snow performance and is excellent in low heat generation.

  The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that the above-mentioned problems can be solved by mixing a diene-based rubber with a specific tetrazine-based compound. The present inventors have further studied based on such findings, and have completed the present invention.

The present invention provides a rubber composition and a studless tire for a tire for icy and snowy roads described below.
Item 1.
Diene rubber and the following general formula (1):

[In the formula, X ¹ and X ² represent a heterocyclic group which may have a substituent. ]
A rubber composition for a tire for ice and snow roads containing a tetrazine compound or a salt thereof represented by
A rubber composition comprising 0.1 to 10 parts by mass of the tetrazine compound or a salt thereof with respect to 100 parts by mass of a diene rubber.
Item 2.
Item 2. The rubber composition according to Item 1, further comprising an inorganic filler and / or carbon black.
Item 3.
Item 3. The rubber composition according to item 2, comprising a total amount of the inorganic filler and / or carbon black of 30 to 130 parts by mass with respect to 100 parts by mass of the diene rubber.
Item 4.
Item 4. The rubber composition according to item 2 or 3, wherein the inorganic filler is silica.
Item 5.
The rubber composition according to any one of Items 1 to 4, which is used for a tread portion.
Item 6.
Item 5. A tread for a tire for icy and snowy roads produced using the rubber composition according to any one of items 1 to 4.
Item 7.
Item 7. A studless tire produced using the tread for ice and snowy roads according to item 6.

  According to the present invention, a rubber composition capable of exhibiting excellent low heat build-up while maintaining snow performance by combining a diene rubber and a tetrazine compound represented by the general formula (1) or a salt thereof is provided. Can be provided.

  Further, by producing a studless tire using the rubber composition of the present invention, the snow performance of the tire can be maintained, and the heat build-up of the tire can be further reduced. Tires can be provided.

  Hereinafter, the present invention will be described in detail.

1. The present invention relates to a diene-based rubber and the following general formula (1):

[In the formula, X ¹ and X ² represent a heterocyclic group which may have a substituent. ]
A rubber composition for tires for ice and snow roads, comprising a tetrazine compound or a salt thereof (hereinafter, also referred to as “tetrazine compound (1)”) represented by
A rubber composition comprising the tetrazine compound or a salt thereof in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of the diene rubber.

Diene rubber The rubber component blended in the rubber composition of the present invention is a diene rubber. Examples of the diene rubber include natural rubber (NR), synthetic diene rubber, and a mixture of natural rubber and synthetic diene rubber. When the rubber component is a diene rubber, a rubber composition having excellent low heat build-up can be obtained. Although the rubber composition of the present invention contains only a diene rubber as a rubber component, it is also allowable that a rubber other than the diene rubber, for example, a non-diene rubber is inevitably contained as an impurity.

  Natural rubber includes natural rubber latex, technical graded rubber (TSR), smoked seat (RSS), gutta percha, natural rubber derived from Tochu, natural rubber derived from guayule, natural rubber derived from Russian dandelion, and fermented rubber derived from plant components. In addition, modified natural rubbers such as epoxidized natural rubber, methacrylic acid-modified natural rubber, and styrene-modified natural rubber are exemplified.

  Examples of the synthetic diene rubber include styrene-butadiene copolymer rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), nitrile rubber (NBR), chloroprene rubber (CR), and ethylene-propylene-diene terpolymer. Examples include polymer rubber (EPDM), styrene-isoprene-styrene triblock copolymer (SIS), styrene-butadiene-styrene triblock copolymer (SBS), and modified synthetic diene rubbers thereof. Examples of the modified synthetic diene rubber include a diene rubber obtained by a modification technique such as main chain modification, one end modification, or both terminal 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, and a carboxyl group. Things. The ratio of cis / trans / vinyl in the diene portion is not particularly limited, and any ratio can be suitably used. The average molecular weight and molecular weight distribution of the diene rubber are not particularly limited, and preferably have an average molecular weight of 5 to 3,000,000 and a molecular weight distribution of 1.5 to 15. The method for producing the synthetic diene rubber is also not particularly limited, and examples thereof include those synthesized by emulsion polymerization, solution polymerization, radical polymerization, anionic polymerization, and cationic polymerization.

  The butyl rubber is a copolymer of isobutylene and a small amount of isoprene rubber and contains 3 mol% or less of double bonds, but is not included in the diene rubber in this specification.

  In addition, the glass transition point of the diene rubber in the range of -120 ° C to -15 ° C is effective from the viewpoint of achieving both low heat generation and snow performance. In the rubber composition of the present invention, 50% by mass or more of the diene rubber is preferably a diene rubber having a glass transition point in the range of -70 ° C to -20 ° C.

  The diene rubber can be used alone or as a mixture (blend) of two or more. Among them, preferred diene rubbers are natural rubber, IR, SBR, BR, or a mixture of two or more selected from these. The blending ratio is not particularly limited, and it is preferable that natural rubber, SBR, BR or a mixture thereof is blended at a ratio of 70 to 100 parts by mass in 100 parts by mass of the diene rubber, and 75 to 100 parts by mass. It is more preferable to mix in parts by mass. When blending a mixture of natural rubber, SBR and BR, the total amount of natural rubber, SBR and BR is preferably within the above range.

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 the formula, X ¹ and X ² represent a heterocyclic group which may have a substituent. ]

  In the present specification, the “heterocyclic group” is not particularly limited and includes, for example, 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-pyridazyl 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-thiadiazolyl) group, 2- (1,3,4-thiadiazolyl) group ) Group, 4- (1,2,3-oxadiazolyl) group, 5- (1,2,3-oxadiazolyl) group, 3- (1,2,4-oxadiazolyl) group, 5- (1,2,2 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-isoindori Group, 3-isoindolyl group, 4-isoindolyl group, 5-isoindolyl group, 6-isoindolyl group, 7-isoindolyl group, 1-benzimidazolyl group, 2-benzimidazolyl group, 4-benzimidazolyl group, 5-benzimidazolyl group, 6-benzimidazolyl Group, 7-benzimidazolyl group, 2-benzofuranyl group, 3-benzofuranyl group, 4-benzofuranyl group, 5-benzofuranyl group, 6-benzofuranyl group, 7-benzofuranyl group, 1-isobenzofuranyl group, 3-isobenzofuran group A 4-isobenzofuranyl group, a 5-isobenzofuranyl group, a 6-isobenzofuranyl group, a 7-isobenzofurnyl group, a 2-benzothienyl group, a 3-benzothienyl group, a 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-benzooxazolyl group, 2-benzothiazolyl group , 4-benzothiazolyl, 5-benzothiazolyl, 6-benzothiazolyl, 7-benzothiazolyl, 1-indazolyl, 3-indazolyl, 4-indazolyl, 5-indazolyl, 6-indazolyl, 7-indazolyl , 2-morpholinyl group, 3-morpholinyl group, 4-morpholinyl 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, preferred heterocyclic groups are 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 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, and a nitro group. Groups, alkyl groups, hydroxyalkyl groups, hydroxyl groups, alkoxy groups, aryl groups, aryloxy groups, heterocyclic groups, thiol groups, alkylthio groups, arylthio groups and the like. The substituent may have preferably 1 to 5, more preferably 1 to 3.

  In the present specification, the “halogen atom” includes a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and is preferably a chlorine atom, a bromine atom, and an iodine atom.

In the present 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 (especially 1 to 4 carbon atoms) such as an amino group; and 1 to 6 carbon atoms such as a dimethylamino group, an ethylmethylamino group, and a diethylamino group (especially 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 may be, for example, an aminoalkyl group such as an aminomethyl group, a 2-aminoethyl group, and a 3-aminopropyl group (preferably having an amino group and having 1 carbon atom. To 6 linear or branched alkyl groups).

  In the present specification, the “alkoxycarbonyl group” is not particularly limited, and includes, for example, a methoxycarbonyl group, an ethoxycarbonyl group, and the like.

  In the present specification, the “acyl group” is not particularly limited, and includes, for example, 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 includes, for example, an acetyloxy group, a propionyloxy group, an n-butyryloxy group, and the like.

  In the present specification, the “amide group” is not particularly limited and includes, for example, a carboxylic amide group such as an acetamide group and a benzamide group; a thioamide group such as a thioacetamide group and a thiobenzamide group; an N-methylacetamide group; 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-pentyl group, and a carboxy group. And 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 “alkyl group” is not particularly limited, and includes, for example, a linear, branched, or cyclic alkyl group. Specifically, 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 Linear or branched alkyl group having 1 to 6 (particularly 1 to 4 carbon atoms) such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group and cyclooctyl; And 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, a hydroxy-alkyl group such as a hydroxymethyl group, a hydroxyethyl group, a hydroxy-n-propyl group, a hydroxy-n-butyl group (preferably 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. Specifically, for example, a methoxy, ethoxy group, an n-propoxy group , An isopropoxy group, an n-butoxy group, a t-butoxy group, an n-pentyloxy group, a neopentyloxy group, a n-hexyloxy group having 1 to 6 (particularly 1 to 4 carbon atoms) linear or A branched alkoxy group; a cyclic 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. And an alkoxy group.

  In the present specification, the “aryl group” is not particularly limited, and includes, for example, a phenyl group, a biphenyl group, a naphthyl group, a dihydroindenyl group, a 9H-fluorenyl group and the like.

  In the present specification, the “aryloxy group” is not particularly limited, and includes, for example, a phenoxy group, a biphenyloxy group, a naphthoxy group, and the like.

  In the present specification, the “alkylthio group” is not particularly limited, and includes, for example, a linear, branched, or cyclic alkylthio group. Specifically, for example, a methylthio group, an ethylthio group, 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 Or a straight-chain or branched alkylthio group having 1 to 6 carbon atoms (especially 1 to 4 carbon atoms) such as a 3-methylpentylthio group; cyclopropylthio group, cyclobutylthio group, cyclopentylthio group, cyclohexylthio Alkylthio group 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 includes, for example, a phenylthio group, a biphenylthio group, a naphthylthio group, and the like.

  The “salt” of the tetrazine compound represented by the general formula (1) is not particularly limited, and includes all kinds of salts. Such salts include, for example, inorganic acid salts such as hydrochloride, sulfate and nitrate; organic acid salts such as acetate and methanesulfonate; alkali metal salts such as sodium salt and potassium salt; magnesium salt and calcium Alkaline earth metal salts such as salts; and ammonium salts such as dimethylammonium and triethylammonium.

Preferred tetrazine compounds (1) are those wherein 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. 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 preferred tetrazine compound (1) is a compound in which X ¹ and X ² are the same or different and each may be a 2-pyridyl group optionally having a substituent, a 3-pyridyl group optionally having a substituent, 4-pyridyl group optionally having a group, 2-furanyl group optionally having a substituent, 2-thienyl group optionally having a substituent, optionally having 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 specifically has a substituent. A compound which is a 2-pyridyl group which may be optionally substituted, a 3-pyridyl group which may have a substituent, or a 2-furanyl group which may have a substituent is 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.

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

  The compounding amount of the tetrazine compound (1) is usually 0.1 to 10 parts by mass, preferably 0.25 to 5 parts by mass, more preferably 0.25 to 5 parts by mass, based on 100 parts by mass of the diene rubber in the rubber composition. Is 0.5 to 2 parts by mass.

  When the tetrazine compound (1) is a powder, its volume average diameter is not particularly limited. From the viewpoint of low heat build-up, 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 from a volume-based particle size distribution as a particle size corresponding to 50% of an integrated distribution curve using a particle size distribution measuring device such as a laser light diffraction method.

  Further, from the viewpoint of handling properties and ignitability or explosive risk reduction at the time of handling, powders that are surface-treated with oil, resin, stearic acid, etc., may be used, or powders such as calcium carbonate, silica, etc. May be used in admixture with a filler or the like.

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

  The compounding 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 diene rubber.

  The compounding amount of carbon black is usually from 2 to 150 parts by mass, preferably from 4 to 120 parts by mass, more preferably from 6 to 100 parts by mass, based on 100 parts by mass of the diene rubber.

  In the rubber composition of the present invention, the inorganic filler and / or carbon black is usually 30 to 130 parts by mass, preferably 40 to 100 parts by mass, based on the total amount of both components, based on 100 parts by mass of the diene rubber. What is necessary is just to adjust suitably within the said compounding quantity range of each component so that it may be set to 130 mass parts, more preferably 45 to 100 mass parts.

  When the total amount of the inorganic filler and / or carbon black is 30 parts by mass or more, it is preferable from the viewpoint of improving the snow performance of the rubber composition, and when it is 130 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 masterbatch polymer which has been mixed with the polymer in a wet or dry manner in advance may be used.

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 usable inorganic compounds include, for example, 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; , Bayerite, etc .; aluminum hydroxide [Al (OH) ₃ ]; aluminum carbonate [Al ₂ (CO ₃ ) ₃ ], 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 ], 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 ₂ SiO _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. The surface of the inorganic filler may be organically treated in order to improve the affinity with the rubber component.

  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, more preferably wet silica. These silicas may be organically treated on the surface of the inorganic filler in order to improve the affinity with the rubber component.

Among them, silica is preferable as the inorganic filler from the viewpoint of snow performance, and the BET specific surface area of the silica is not particularly limited, and for example, is in a range of 40 to 350 m ² / g. Silica having a BET specific surface area within this range is advantageous in that it can achieve both snow performance and dispersibility in a rubber component. The BET specific surface area is measured according to ISO 5794/1.

From this viewpoint, preferred silica is silica having a BET specific surface area of 50 to 250 m ² / g, more preferably silica having a BET specific surface area of 80 to 230 m ² / g, and particularly preferably. , Silica having a BET specific surface area of 100 to 210 m ² / g. Further, these silicas having different BET specific surface areas may be used in combination.

Commercial products of such silica include 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 = 200 m ² / g), “HD250MP” (BET specific surface area = 250 m ² / g), trade name “Nip Seal AQ” manufactured by Tosoh Silica Corporation (BET specific surface area = 205 m ² / g) ), “Nip Seal KQ” (BET specific surface area = 240 m ² / g), Degussa product name “Ultrasil VN3” (BET specific surface area = 175 m ² / g), Solvay product name “Z1085Gr” (BET) 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.

  The compounding amount of silica is usually 20 to 120 parts by mass, preferably 30 to 100 parts by mass, and more preferably 40 to 90 parts by mass based on 100 parts by mass of the diene rubber.

The carbon black is not particularly limited, and examples thereof 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 and the like. Among them, preferred carbon black is 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 (N2SA, measured according to JIS K 6217-2: 2001) of carbon black 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.

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

Other Compounding Agents In addition to the above-mentioned tetrazine compound (1) and inorganic filler and / or carbon black, the rubber composition of the present invention may contain other compounding agents commonly used in the rubber industry, such as sulfur. A sulfurizing agent can be blended. The rubber composition of the present invention may further contain another compounding agent, for example, an antioxidant, an antiozonant, a softener, a processing aid, a wax, a resin, a foaming agent, an oil, stearic acid, and zinc oxide (ZnO). , A vulcanization accelerator, a vulcanization retarder and the like. These compounding agents can be appropriately selected and compounded within a range that does not impair the purpose of the present invention. Commercially available products can be suitably used as these compounding agents.

  Further, in a rubber composition in which an inorganic filler such as silica is blended, silane coupling is used for the purpose of enhancing the reinforcing property of the rubber composition with silica, or the purpose of increasing the wear resistance together with the low heat build-up of the rubber composition. You may mix | blend an agent.

  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 suitably used. 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 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-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 the thioester 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-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, 3-mercaptopropylmethyldimethoxysilane, and 3- [ethoxybis (3,6,9,12,15). -Pentaoxaoctakosan-1-yloxy) silyl] -1-propanethiol.

  Examples of the olefin-based silane coupling agent include dimethoxymethylvinylsilane, vinyltrimethoxysilane, dimethylethoxyvinylsilane, diethoxymethylvinylsilane, triethoxyvinylsilane, vinyltris (2-methoxyethoxy) silane, allyltrimethoxysilane, and allyltrimethoxysilane. Ethoxysilane, p-styryltrimethoxysilane, 3- (dimethoxymethylsilyl) 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 (trimethylsilo) Shi) silyl] propyl methacrylate, and the like.

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

  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 preferred.

  Examples of the alkyl silane coupling agent include, for example, methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane Examples thereof 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, bis (3-triethoxysilylpropyl) disulfide, and 3- [ethoxybis (3,6,9,12,15-pentaoxaocta) [Cosan-1-yloxy) silyl] -1-propanethiol 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 compounding amount of the silane coupling agent in 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. When the amount is 0.1 parts by mass or more, the effect of low heat build-up of the rubber composition can be more suitably exhibited, and when the amount is 20 parts by mass or less, the cost of the rubber composition is reduced and the economic efficiency is improved. Because you do.

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

  In the case of emphasizing processability, as a processing aid, mineral oil, petrolatum, paraffin wax, petroleum resin, fatty acid, fatty acid ester, fatty alcohol, metal soap, fatty acid amide, phenol resin, polyethylene, polybutene, peptizer, Regenerating agents, organosiloxanes and the like can be added.

Use of rubber composition The use of the rubber composition of the present invention is a tread for tires for icy and snowy roads.

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 (I) of mixing a diene rubber, a tetrazine compound (1), and a raw material component containing an inorganic filler and / or carbon black as necessary, and a step Step (II) of mixing the mixture obtained in (I) and the vulcanizing agent is included. In the present specification, “mixing” includes “kneading”.

Step (I)
Step (I) is a step of mixing a diene rubber, a tetrazine compound (1), and raw material components containing an inorganic filler and / or carbon black as necessary, and is a step before compounding a vulcanizing agent. It means there is. In this step (I), the tetrazine compound (1) reacts with the double bond of the diene rubber.

  In the step (I), the above-mentioned other compounding agents can be further compounded, if necessary.

  Examples of the mixing method in the step (I) include a method of mixing a composition containing a diene rubber, a tetrazine compound (1), an inorganic filler and / or carbon black. In this mixing method, the entire amount of each component may be kneaded at a time, or each component may be dividedly charged and kneaded according to the purpose of viscosity adjustment or the like. Further, after kneading the diene rubber and the inorganic filler and / or carbon black, the tetrazine compound (1) is charged and mixed, or the diene rubber and the tetrazine compound (1) are mixed, and then the inorganic filler is mixed. Materials and / or carbon black may be added and mixed. Step (I) may be repeatedly mixed multiple times.

  The temperature at which the rubber composition is mixed in the step (I) may be a temperature at which the tetrazine compound (1) reacts with the diene rubber. For example, the upper limit of the temperature of the rubber composition is 120 to The temperature is preferably 190 ° C, more preferably 130 to 175 ° C, and even more preferably 140 to 170 ° C.

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

  In the step (I), the blending amount of the tetrazine compound (1) is not particularly limited, and is, for example, 0.1 to 10 parts by mass, preferably 0.25 to 5 parts by mass, based on 100 parts by mass of the diene rubber. It is 5 parts by mass, more preferably 0.5 to 2 parts by mass.

  The compounding amount of the inorganic filler in the step (I) 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 diene rubber. Department.

  The compounding amount of carbon black in the step (I) is usually 2 to 150 parts by mass, preferably 4 to 120 parts by mass, more preferably 6 to 100 parts by mass with respect to 100 parts by mass of the diene rubber. It is.

  In the step (I), the amount of the inorganic filler and / or carbon black is usually 30 to 130 parts by mass based on 100 parts by mass of the diene rubber. What is necessary is just to adjust suitably within the range of a compounding quantity.

  Further, as another mixing method in the step (I), a step (I-1) of mixing the rubber component and the tetrazine compound (1), and the mixture obtained in the step (I-1) and an inorganic filler are used. And / or a two-stage mixing method including a step (I-2) of mixing with carbon black.

  In the step (I-1), as a method of mixing the diene rubber and the tetrazine compound (1), when the diene rubber is solid, a method of kneading the diene rubber and the tetrazine compound (1) ( Solid mixing method); when the diene rubber is liquid (liquid), a method of mixing the diene rubber solution or emulsion (suspension) with the tetrazine compound (1) (liquid mixing method) and the like. No.

  The mixing temperature may be any amount of heat required for the tetrazine compound (1) to react with the diene-based rubber. For example, in the case of the solid mixing method, the upper limit of the temperature of the rubber composition is 80 to 190 ° C. The temperature is preferably 90 to 160 ° C, 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 from 80 to 170 ° C, more preferably from 90 to 160 ° C, and still more preferably from 100 to 150 ° C.

  For example, in the case of the solid mixing method, the mixing time is preferably from 10 seconds to 20 minutes, more preferably from 30 seconds to 10 minutes, and even more preferably from 60 seconds to 7 minutes. In the case of the liquid mixing method, the time is preferably from 10 seconds to 60 minutes, more preferably from 30 seconds to 40 minutes, even more preferably from 60 seconds to 30 minutes. After the mixing reaction by the liquid mixing method, for example, the solvent in the mixture is removed (removed) under reduced pressure to recover a solid rubber composition.

  The blending amount of the tetrazine compound (1) in the step (I-1) is not particularly limited, and is, for example, usually 0.1 to 10 parts by mass, preferably 0.1 to 10 parts by mass, based on 100 parts by mass of the diene rubber. It is 25 to 5 parts by mass, more preferably 0.5 to 2 parts by mass.

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

  The temperature at which the mixture (modified polymer) obtained in step (I-1) and the inorganic filler and / or carbon black are mixed in step (I-2) is not particularly limited. The upper limit of the temperature is preferably from 120 to 190 ° C, more preferably from 130 to 175 ° C, and even more preferably from 140 to 170 ° C.

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

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

  The amount of the carbon black in the step (I-2) is usually 2 to 150 parts by weight, preferably 4 to 100 parts by weight, based on 100 parts by weight of the mixture (modified polymer) obtained in the step (I-1). It is 120 parts by mass, more preferably 6 to 100 parts by mass.

  In the step (I-2), the inorganic filler and / or carbon black may be used in a total amount of both components, for example, based on 100 parts by mass of the mixture (modified polymer) obtained in the step (I-1). The amount of each component may be appropriately adjusted within the above-mentioned range of the compounding amount so as to be usually 20 to 150 parts by mass.

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

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

  The mixing temperature in the step (II) is not particularly limited, and is, for example, preferably from 60 to 140 ° C, more preferably from 80 to 120 ° C, and still more preferably from 90 to 120 ° C.

  The mixing time is not particularly limited, and is, for example, preferably from 10 seconds to 20 minutes, more preferably from 30 seconds to 10 minutes, and still more preferably from 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 stearic acid, zinc white, a vulcanization accelerator, an antioxidant and the like which are usually compounded in the rubber composition are optionally added to the step (I). Alternatively, it can be added in step (II).

  Through the above steps (I) and (II), a rubber composition containing a modified polymer obtained by treating the diene rubber with the tetrazine compound (1), and an inorganic filler and / or carbon black is produced. be able to.

  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 bond-requesting 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 the formula (B-1). ) To form a bicyclo ring structure. The -N = N- part in the bicyclo ring structure has a six-membered ring structure represented by the formula (C-1), (C-2) or (C-3) in which denitrification easily proceeds. The modified polymer is formed but is further oxidized by oxygen in the air to produce a modified polymer having a six-membered ring structure represented by the formula (2-1).

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

  In Reaction Formula-2, as in 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 ( After forming a bicyclo ring structure represented by B-2 ′) and then a six-membered ring structure represented by formulas (C-4) to (C-9), the compound represented by formula (2-2) or (2-3) ), A modified polymer having a six-membered ring structure is produced.

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, the double bond site of the diene rubber represented by the formula (A-3) and the tetrazine compound (1) are subjected to a reverse electron-requesting Aza-Diels-Alder reaction to obtain the compound of the formula (B-3). ) Or a modified polymer having a six-membered ring structure represented by formulas (2-4) to (2-7) by denitrification after forming a bicyclo ring structure represented by (B-3 ′). Manufactured. When R is a halogen atom on the double bond site of the diene rubber represented by the formula (A-3), 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) causes the reaction of the formula (B- 4) Alternatively, 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. You.

  As described above, the produced modified polymer has a hetero atom such as a nitrogen atom, and the hetero atom strongly interacts with the inorganic filler (particularly silica) and carbon black. The dispersibility in the inside can be enhanced, and high low heat generation can be imparted.

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

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

2. Studless 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.

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

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

  In the tire of the present invention, the rubber composition is used particularly for a tread portion.

  Above all, one of the preferable embodiments is to form the tire tread portion of the pneumatic studless tire with the rubber composition.

  The tire tread portion has a tread pattern, is a portion directly in contact with a road surface, is a skin portion of the tire that protects a carcass and prevents abrasion and damage, and is a cap tread and / or a cap tread that constitutes a ground contact portion of the tire. Refers to the base tread that is arranged inside.

  The tire of the present invention can be manufactured according to a method known hitherto in the field of tires.

  As the gas to be charged into the tire, there can be used normal air or air whose oxygen partial pressure is adjusted; an inert gas such as nitrogen, argon, or helium.

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

Production Example 1: Production of 3,6-bis (3-pyridyl) -1,2,4,5-tetrazine (a) In a 200 mL four-neck flask, 24 g (0.23 mol) of 3-cyanopyridine and water were added. 15 g (1.3 equivalents) of hydrazine and 48 mL of methanol were added, and the mixture was stirred at room temperature. Next, 3.6 g (15% by weight) of sulfur was added to the mixture, and the mixture was heated and stirred at an external temperature of 70 ° C. overnight with a reflux tube attached. The reaction was cooled on ice 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. The dihydrotetrazine acetic acid solution and 178 mL of distilled water were added to a 1 L four-necked eggplant flask, and the mixture was 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 at room temperature overnight. The precipitated crystals were filtered, and the crystals were neutralized with 10% aqueous layer water to obtain crude crystals. The crude crystals were purified by a silica gel column (ethyl acetate) to obtain 8.4 g (magenta, needle-like crystals) of the title tetrazine compound (a).
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 to 6
The components described in the step (I) in Table 1 below were mixed in the proportions (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 the mixture until the temperature of the mixture becomes 80 ° C. or lower, each component described in the step (II) in Table 1 is added in the ratio (parts by mass), and the mixture is adjusted so that the maximum temperature of the mixture is 110 ° C. or lower. While kneading, each rubber composition was produced.

Low heat build-up (tan δ index) Test For the rubber compositions (test compositions) produced in Examples 1 to 6, using a viscoelasticity measuring device (manufactured by Metravib), temperature 40 ° C., dynamic strain 5%, frequency 15 Hz Was measured for tan δ.

  Except that the tetrazine compound (1) was not added, a rubber composition (reference) was produced by the same blending content and the same production method as in each example, and a low heat build-up index was calculated based on the following formula.

  The larger the value of the low heat buildup index, the lower the heat buildup, and the smaller the hysteresis loss. The low heat build-up of the vulcanized rubber composition of each reference is set to 100.

  The results are shown in Table 1.

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

Ice and snow performance test The rubber compositions (test compositions) and references prepared in Examples 1 to 6 were stored at a temperature of −20 ° C., a dynamic strain of 1%, and a frequency of 10 Hz using a viscoelasticity measuring device (manufactured by Metravib). The elastic modulus was measured.

Formula: Ice snow performance index = {(storage elastic modulus of reference) / (storage elastic modulus of test composition)} x 100

[Explanation of symbols in table]
The raw materials used in Table 1 are shown below.
* 1: "Tuffden 2000R" manufactured by Asahi Kasei Corporation
* 2: Product name "BR150B" manufactured by Ube Industries, Ltd.
* 3: Made by Chuka International Co., Ltd., product name "RSS $ 3"
* 4: Product name “Nipsil (brand AQ)” manufactured by Tosoh Silica Corporation
* 5: Product name “Si69” manufactured by Evonik Industries AG
* 6: Tokai Carbon Co., Ltd., product name "Seast 3"
* 7: Product name “Antilux 111” manufactured by Rhein Chemie Rheinau GmbH
* 8: Product name “Antage 6C” manufactured by Kawaguchi Chemical Industry Co., Ltd.
* 9: Zinc oxide brand “1” made by Sakai Chemical Industry Co., Ltd.
* 10: Made by Sichuan Tianyu Grease Chemical Co., Ltd. * 11: Made by JX Nippon Oil & Energy Corporation, trade name "X-140 (Aroma Oil)"
* 12: 3,6-bis (3-pyridyl) -1,2,4,5-tetrazine (compound produced in Production Example 1)
* 13: 3,6-bis (2-pyridyl) -1,2,4,5-tetrazine, manufactured by Tokyo Chemical Industry Co., Ltd. * 14: 3,6-bis (4-pyridyl) -1,2,4 5-Tetrazine, manufactured by Tokyo Chemical Industry Co., Ltd. * 15: "HK200-5" manufactured by Hosoi Chemical Industry Co., Ltd.
* 16: Made by Ouchi Shinko Chemical Co., Ltd., trade name "Noxeller D"
* 17: Made by Ouchi Shinko Chemical Co., Ltd., trade name “Noxeller CZ-G”

  Since the rubber composition for tires on ice and snow roads of the present invention maintains snow performance and is much more excellent in low heat build-up, the use of the rubber composition produces a tread portion (tire tread) of a studless tire. be able to.

Claims (7)

Diene rubber and the following general formula (1):

[In the formula, X ¹ and X ² represent a heterocyclic group which may have a substituent. ]
A rubber composition for a tire for ice and snow roads containing a tetrazine compound or a salt thereof represented by
A rubber composition comprising 0.1 to 10 parts by mass of the tetrazine compound or a salt thereof with respect to 100 parts by mass of a diene rubber. The rubber composition according to claim 1, further comprising an inorganic filler and / or carbon black. The rubber composition according to claim 2, comprising 30 to 130 parts by mass of the inorganic filler and / or carbon black in a total amount based on 100 parts by mass of the diene rubber. The rubber composition according to claim 2 or 3, wherein the inorganic filler is silica. The rubber composition according to any one of claims 1 to 4, which is used for a tread portion. A tread for a tire for icy and snowy roads, produced using the rubber composition according to any one of claims 1 to 4. A studless tire manufactured using the tread for an ice-snow road according to claim 6.