CN110392713B

CN110392713B - Rubber composition and tire

Info

Publication number: CN110392713B
Application number: CN201880017043.7A
Authority: CN
Inventors: 佐藤崇; 汤浅宏昭; 中岛慎也
Original assignee: Otsuka Chemical Co Ltd
Current assignee: Otsuka Chemical Co Ltd
Priority date: 2017-03-10
Filing date: 2018-03-09
Publication date: 2022-02-18
Anticipated expiration: 2038-03-09
Also published as: JP6701434B2; CN110392713A; WO2018164247A1; JPWO2018164247A1

Abstract

A rubber composition comprising a rubber component, a tetrazine compound represented by the following general formula (1) or a salt thereof, and carbon black, wherein 100 parts by mass of the rubber component comprises 40 parts by mass or more of a natural rubber, and 0.1 to 10 parts by mass of the tetrazine compound or the salt thereof, and 30 to 120 parts by mass of the carbon black are contained per 100 parts by mass of the rubber component. [ in the formula, X¹And X²Represents a heterocyclic group which may have a substituent.]

Description

Rubber composition and tire

Technical Field

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

Background

In recent years, in view of environmental concerns, regulations for carbon dioxide emission have become strict worldwide, and the demand for low fuel consumption of automobiles has become very high. In order to reduce fuel consumption, the contribution of efficiency of a drive system such as an engine and a transmission system is large, but rolling resistance of tires also largely contributes, and it is important to reduce rolling resistance in order to reduce fuel consumption of an automobile. Further, heavy duty tires for large automobiles such as trucks and buses are required to have not only low rolling resistance but also wear resistance.

As a method for reducing the rolling resistance of a tire, it is known to apply a rubber composition having low heat build-up to a tire. Examples of such a rubber composition having a low heat build-up include: (1) a rubber composition containing a functionalized polymer having improved affinity for carbon black and silica as fillers (patent document 1); (2) a rubber composition containing a diene elastomer, an inorganic filler as a reinforcing filler, a polysulfurized alkoxysilane as a coupling agent, 1, 2-dihydropyridine, and a guanidine derivative (patent document 2); (3) a rubber composition containing a rubber component, an aminopyridine derivative, and an inorganic filler (patent document 3); (4) a rubber composition containing a terminal-modified polymer and an inorganic filler (patent documents 4 and 5); and so on.

According to the inventions described in patent documents 1 to 5, the heat build-up of the rubber composition can be reduced by increasing the affinity between the filler and the rubber component, and as a result, a tire having a low hysteresis loss (rolling resistance) can be obtained.

However, even when the rubber compositions of patent documents 1 to 5 are used, the improvement of the low heat build-up is not sufficient. Further, by improving the low heat buildup of the rubber composition, the decrease in abrasion resistance cannot be avoided.

The demand for lower fuel consumption of automobiles is further increasing, and development of tires having very excellent low heat build-up is strongly desired.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2003-514079

Patent document 2: japanese Kohyo publication No. 2003-523472

Patent document 3: japanese patent laid-open publication No. 2013-108004

Patent document 4: japanese patent laid-open No. 2000-169631

Patent document 5: japanese patent laid-open publication No. 2005-220323

Disclosure of Invention

Problems to be solved by the invention

The purpose of the present invention is to provide a rubber composition which has excellent abrasion resistance and low heat build-up and is suitable for the production of heavy-duty tires for large automobiles.

Another object of the present invention is to provide a tire having excellent abrasion resistance and low heat buildup.

Means for solving the problems

The inventors of the present application have made intensive studies to solve the above problems, and as a result, have found that the above problems can be solved by adding a specific amount of carbon black to a rubber composition containing a rubber component including a natural rubber and a tetrazine-based compound. The inventors of the present application have further conducted studies based on the above findings, and as a result, have finally completed the present invention.

The present invention provides a rubber composition, a tire, and the like as shown below.

Item 1.

A rubber composition comprising a rubber component, a tetrazine compound represented by the following general formula (1) or a salt thereof, and carbon black,

[ chemical formula 1]

[ in the formula, X¹And X²Represents a heterocyclic group which may have a substituent.]

The rubber component contains 40 parts by mass or more of natural rubber per 100 parts by mass of the rubber component,

the tetrazine compound or a salt thereof and 30 to 120 parts by mass of carbon black are contained in an amount of 0.1 to 10 parts by mass per 100 parts by mass of the rubber component.

Item 2.

The rubber composition as described in item 1, wherein the carbon black has a nitrogen adsorption specific surface area of 50 to 160m²/g。

Item 3.

The rubber composition as described in the item 1 or 2, which further comprises an inorganic filler.

Item 4.

The rubber composition as described in item 3, wherein the inorganic filler is silica.

Item 5.

The rubber composition as described in item 4, wherein the silica has a BET specific surface area (m)²/g) wet silica in the range of 40 to 350.

Item 6.

The rubber composition as described in any of the above 3 to 5, wherein the amount of the inorganic filler blended is 20 to 150 parts by mass with respect to 100 parts by mass of the rubber composition.

Item 7.

The rubber composition as described in any one of items 1 to 6, which is used for a tread portion.

Item 8.

A tread for a tire, which is produced using the rubber composition according to any one of items 1 to 6.

Item 9.

A pneumatic tire using the tread for a tire according to item 8.

Item 10.

The tire according to item 9, which is used for a heavy load tire for a large automobile.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a rubber composition which can impart not only excellent low heat build-up but also excellent abrasion resistance to a tire can be provided by combining a specific rubber component, a tetrazine compound represented by the general formula (1) or a salt thereof, and carbon black.

Further, by producing a tire using the rubber composition of the present invention, it is possible to improve abrasion resistance while reducing rolling resistance of the tire and reducing heat build-up of the tire, and therefore, it is possible to provide a low fuel consumption tire for large automobiles.

Detailed Description

The present invention will be described in detail below.

1. Rubber composition

The present invention is a rubber composition containing a rubber component, a tetrazine compound represented by the following general formula (1) or a salt thereof (hereinafter, also referred to as "tetrazine compound (1)"), and carbon black,

[ chemical formula 2]

Rubber component

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

Examples of the natural rubber include natural rubber such as natural rubber latex, technical grade rubber (TSR), tabella Rubber (RSS), gutta percha, natural rubber derived from eucommia ulmoides, natural rubber derived from guayule, natural rubber derived from russian dandelion, and plant component fermented rubber, and in addition, modified natural rubber such as epoxidized natural rubber, methacrylic acid-modified natural rubber, and styrene-modified natural rubber.

Examples of the synthetic diene rubber include styrene-butadiene copolymer rubber (SBR), Butadiene Rubber (BR), Isoprene Rubber (IR), acrylonitrile-butadiene copolymer rubber (NBR), Chloroprene Rubber (CR), ethylene-propylene-diene terpolymer 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 diene rubbers obtained by modification methods such as main chain modification, single-end modification, and both-end modification. Examples of the modifying functional group for modifying the synthetic diene rubber include a modifying functional group containing 1 or more kinds of hetero atom-containing functional groups such as an epoxy group, an amino group, an alkoxy group, a hydroxyl group, an alkoxysilyl group, a polyether group, and a carboxyl group. In addition, the ratio of cis/trans/vinyl groups of the diene moiety is not particularly limited, and any ratio may be suitably used. The average molecular weight and molecular weight distribution of the diene rubber are not particularly limited, and diene rubbers having an average molecular weight of 500 to 300 ten thousand can be preferably used. The method for producing the synthetic diene rubber is not particularly limited, and examples thereof include those using synthesis such as emulsion polymerization, solution polymerization, radical polymerization, anion polymerization, and cation polymerization.

The glass transition temperature of the diene rubber is effective in a range of-120 ℃ to-15 ℃ from the viewpoint of achieving both abrasion resistance and rolling resistance. The rubber composition of the present invention is preferably a diene rubber having a glass transition temperature of-70 ℃ to-20 ℃ in an amount of 50% by mass or more of the diene rubber.

As the non-diene rubber, 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 abrasion resistance. Specifically, the rubber component preferably contains 40 parts by mass or more of natural rubber, and more preferably contains 60 parts by mass or more of natural rubber, per 100 parts by mass of the rubber component.

As the rubber component, 1 kind may be used alone, or 2 or more kinds may be mixed (blended) and used. Among these, the preferable rubber component is natural rubber, IR, SBR, BR, or a mixture of 2 or more selected from them, and more preferably natural rubber, SBR, BR, or a mixture of 2 or more selected from them. The blending ratio of these is not particularly limited, and SBR, BR or a mixture thereof is preferably blended at a ratio of 60 parts by mass or less, and more preferably a mixture thereof is blended at a ratio of 40 parts by mass or less, in 100 parts by mass of the rubber component. When a mixture of SBR and BR is blended, the total amount of SBR and BR is preferably in the above range. In this case, the amount of SBR is preferably 50 to 100 parts by mass and the amount of BR is preferably 0 to 50 parts by mass.

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:

[ chemical formula 3]

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-pyrimidinyl group, a 4-pyrimidinyl group, a 5-pyrimidinyl group, a 3-pyridazinyl group, a 4- (1, 2, 3-triazine) group, a 5- (1, 2, 3-triazine) group, a 2- (1, 3, 5-triazine) group, a 3- (1, 2, 4-triazine) group, a 5- (1, 2, 4-triazine) group, a 6- (1, 2, 4-triazine) group, a 2-quinolyl group, a 3-quinolyl group, a 4-quinolyl group, a 5-quinolyl group, a 6-quinolyl group, a 7-quinolyl group, an 8-quinolyl group, a, 1-isoquinolinyl, 3-isoquinolinyl, 4-isoquinolinyl, 5-isoquinolinyl, 6-isoquinolinyl, 7-isoquinolinyl, 8-isoquinolinyl, 2-quinoxalinyl, 3-quinoxalinyl, 5-quinoxalinyl, 6-quinoxalinyl, 7-quinoxalinyl, 8-quinoxalinyl, 3-cinnolinyl, 4-cinnolinyl, 5-cinnolinyl, 6-cinnolinyl, 7-cinnolinyl, 8-cinnolinyl, 2-quinazolinyl, 4-quinazolinyl, 5-quinazolinyl, 6-quinazolinyl, 7-quinazolinyl, 8-quinazolinyl, 1-phthalazinyl, 4-phthalazinyl, 5-phthalazinyl, 6-phthalazinyl, 7-phthalazinyl, 8-phthalazinyl group, 1-tetrahydroquinolyl group, 2-tetrahydroquinolyl group, 3-tetrahydroquinolyl group, 4-tetrahydroquinolyl group, 5-tetrahydroquinolyl group, 6-tetrahydroquinolyl group, 7-tetrahydroquinolyl group, 8-tetrahydroquinolyl group, 1-pyrrolyl group, 2-pyrrolyl group, 3-pyrrolyl group, 2-furyl group, 3-furyl group, 2-thienyl group, 3-thienyl group, 1-imidazolyl group, 2-imidazolyl group, 4-imidazolyl group, 5-imidazolyl group, 1-pyrazolyl group, 3-pyrazolyl group, 4-pyrazolyl group, 5-pyrazolyl group, 2-oxazolyl group, 4-oxazolyl group, 5-oxazolyl group, 2-thiazolyl group, 4-thiazolyl group, 5-thiazolyl group, 3-isoxazolyl group, 3-pyridyl group, and the like, 4-isoxazolyl, 5-isoxazolyl, 3-isothiazolyl, 4-isothiazolyl, 5-isothiazolyl, 4- (1, 2, 3-thiadiazole) yl, 5- (1, 2, 3-thiadiazole) yl, 3- (1, 2, 5-thiadiazole) yl, 2- (1, 3, 4-thiadiazole) yl, 4- (1, 2, 3-oxadiazole) yl, 5- (1, 2, 3-oxadiazole) yl, 3- (1, 2, 4-oxadiazole) yl, 5- (1, 2, 4-oxadiazole) yl, 3- (1, 2, 5-oxadiazole) yl, 2- (1, 3, 4-oxadiazole) yl, 1- (1, 2, 3-triazole) yl, 4- (1, 2, 3-triazolyl), 5- (1, 2, 3-triazolyl), 1- (1, 2, 4-triazolyl), 3- (1, 2, 4-triazolyl), 5- (1, 2, 4-triazolyl), 1-tetrazolyl, 5-tetrazolyl, 1-indolyl, 2-indolyl, 3-indolyl, 4-indolyl, 5-indolyl, 6-indolyl, 7-indolyl, 1-isoindolyl, 2-isoindolyl, 3-isoindolyl, 4-isoindolyl, 5-isoindolyl, 6-isoindolyl, 7-isoindolyl, 1-benzimidazolyl, 4-benzimidazolyl, 5-benzimidazolyl, 1-benzimidazolyl, 2-benzimidazolyl, 4-benzimidazolyl, 5-benzimidazolyl, 6-benzimidazolyl, 7-benzimidazolyl, 2-benzofuranyl, 3-benzofuranyl, 4-benzofuranyl, 5-benzofuranyl, 6-benzofuranyl, 7-benzofuranyl, 1-isobenzofuranyl, 3-isobenzofuranyl, 4-isobenzofuranyl, 5-isobenzofuranyl, 6-isobenzofuranyl, 7-isobenzofuranyl, 2-benzothienyl, 3-benzothienyl, 4-benzothienyl, 5-benzothienyl, 6-benzothienyl, 7-benzothienyl, 2-benzoxazolyl, 4-benzoxazolyl, 5-benzoxazolyl, 6-benzoxazolyl, 7-benzoxazolyl, 2-benzothiazolyl, 3-benzofuranyl, 4-isobenzofuranyl, 4-benzothiazolyl, 5-benzothiazolyl, 6-benzothiazolyl, 7-benzothiazolyl, 1-indazolyl, 3-indazolyl, 4-indazolyl, 5-indazolyl, 6-indazolyl, 7-indazolyl, 2-morpholinyl, 3-morpholinyl, 4-morpholinyl, 1-piperazinyl, 2-piperazinyl, 1-piperidinyl, 2-piperidinyl, 3-piperidinyl, 4-piperidinyl, 2-tetrahydropyranyl, 3-tetrahydropyranyl, 4-tetrahydropyranyl, 2-tetrahydrothiopyranyl, 3-tetrahydrothiopyranyl, 4-tetrahydrothiopyranyl, 1-pyrrolidinyl, 2-pyrrolidinyl, 3-pyrrolidinyl, 2-tetrahydrofuranyl, 1-morpholinyl, 2-piperazinyl, 1-piperidinyl, 2-tetrahydropyranyl, 4-tetrahydrothiopyranyl, 2-pyrrolidinyl, 3-pyrrolidinyl, 2-tetrahydrofuranyl, 1-piperazinyl, 2-piperazinyl, etc, 3-tetrahydrofuranyl, 2-tetrahydrothienyl, 3-tetrahydrothienyl, and the like. Among them, preferred heterocyclic groups are pyridyl, furyl, thienyl, pyrimidinyl or pyrazinyl, and more preferred is pyridyl.

The heterocyclic group may have 1 or more substituents at positions where substitution is possible. 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, a nitro group, an alkyl group, a hydroxyalkyl group, a hydroxyl group, an alkoxy group, an aryl group, an aryloxy group, a heterocyclic group, a thiol group, an alkylthio group, and an arylthio group. Preferably 1 to 5, more preferably 1 to 3 substituents.

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

In the present specification, "amino" includes not only-NH₂The amino group represented by (a) further includes, for example, a linear or branched monoalkylamino group having 1 to 6 carbon atoms (particularly, having 1 to 4 carbon atoms), such as a methylamino group, an ethylamino group, a n-propylamino group, an isopropylamino group, a n-butylamino group, an isobutylamino group, a sec-butylamino group, a tert-butylamino group, a 1-ethylpropylamino group, a n-pentylamino group, a neopentylamino group, a n-hexylamino group, an isohexylamino group, a 3-methylpentylamino group, etc.; a substituted amino group such as a dialkylamino group having a linear or branched alkyl group having 1 to 6 carbon atoms (particularly 1 to 4 carbon atoms) such as a dimethylamino group, an ethylmethylamino group, or a diethylamino group.

In the present specification, the "aminoalkyl" is not particularly limited, and examples thereof include an aminoalkyl group (preferably, a linear or branched alkyl group having 1 to 6 carbon atoms and an amino group) such as an aminomethyl group, a 2-aminoethyl group, and a 3-aminopropyl group.

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 acetoxy, propionyloxy, n-butyryloxy and the like.

In the present specification, the "amide group" is not particularly limited, and examples thereof include carboxylic acid amide groups such as an acetamide group and a benzamide group; thioamide groups such as thioacetamide groups and thiobenzamide groups; n-substituted amide groups such as N-methylacetamide group and N-benzylacetamide group; and so on.

In the present specification, the "carboxyalkyl group" is not particularly limited, and examples thereof include carboxyalkyl groups (preferably an alkyl group having 1 to 6 carbon atoms of a carboxyl group) such as a carboxymethyl group, a carboxyethyl group, a carboxyl-n-propyl group, a carboxyl-n-butyl group, a carboxyl-n-pentyl group, and a carboxyl-n-hexyl group.

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

The "alkyl group" in the present specification is not particularly limited, and examples thereof include linear, branched or cyclic alkyl groups, and specific examples thereof include linear or branched alkyl groups having 1 to 6 carbon atoms (particularly 1 to 4 carbon atoms) such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, 1-ethylpropyl, n-pentyl, neopentyl, n-hexyl, isohexyl and 3-methylpentyl; and cyclic alkyl groups having 3 to 8 carbon atoms (particularly 3 to 6 carbon atoms) such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl.

The "alkoxy group" as used herein is not particularly limited, and examples thereof include straight-chain, branched-chain or cyclic alkoxy groups, and specific examples thereof include straight-chain or branched-chain alkoxy groups having 1 to 6 carbon atoms (particularly 1 to 4 carbon atoms), such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, tert-butoxy, n-pentyloxy, neopentyloxy, n-hexyloxy, and the like; and cyclic alkoxy groups 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.

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

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

The "alkylthio group" in the present specification is not particularly limited, and examples thereof include linear, branched or cyclic alkylthio groups, and specific examples thereof include linear or branched alkylthio groups having 1 to 6 (particularly 1 to 4) carbon atoms such as methylthio, ethylthio, n-propylthio, isopropylthio, n-butylthio, isobutylthio, sec-butylthio, tert-butylthio, 1-ethylpropylthio, n-pentylthio, neopentylthio, n-hexylthio, isohexylthio, 3-methylpentylthio and the like; and cyclic alkylthio groups having 3 to 8 carbon atoms (particularly 3 to 6 carbon atoms) such as cyclopropylthio, cyclobutylthio, cyclopentylthio, cyclohexylthio, cycloheptylthio and cyclooctylthio.

In the present specification, the "arylthio group" is not particularly limited, and examples thereof include phenylthio group, biphenylthio group, 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. Examples of such salts include 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; alkaline earth metal salts such as magnesium salts and calcium salts; ammonium salts such as dimethylammonium and triethylammonium.

Preferred tetrazine compounds (1) are the following compounds: x¹And X²The same or different is a pyridyl group which may have a substituent, a furyl group which may have a substituent, a thienyl group which may have a substituent, a pyrazolyl group which may have a substituent, a pyrimidinyl group which may have a substituent, or a pyrazinyl group which may have a substituent.

More excellentSelected tetrazine compounds (1) are the following compounds: x¹And X²The same or different, may be 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, a 2-furyl group which may have a substituent, a 2-thienyl group which may have a substituent, a 1-pyrazolyl group which may have a substituent, a 2-pyrimidinyl group which may have a substituent, or a 2-pyrazinyl group which may have a substituent, and specifically, the following compounds are particularly preferable: x¹And X²The same or different, may be 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-furyl group which may have a substituent.

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-furyl) -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-pyrazinyl) -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, 3, 6-bis (3-pyridyl) -1, 2, 4, 5-tetrazine, 3, 6-bis (2-furyl) -1, 2, 4, 5-tetrazine, and 3, 6-bis (4-pyridyl) -1, 2, 4, 5-tetrazine, further 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, and 3, 6-bis (4-pyridyl) -1, 2, 4, 5-tetrazine.

The amount of the tetrazine compound (1) is 0.1 to 10 parts by mass per 100 parts by mass of the rubber component in the rubber composition, from the viewpoint of imparting low rolling resistance to the rubber component. The amount of the tetrazine compound (1) is preferably 0.25 to 5 parts by mass, more preferably 0.5 to 2 parts by mass, per 100 parts by mass of the rubber component in the rubber composition.

When the tetrazine compound (1) is a powder, the volume average particle diameter thereof is not particularly limited. From the viewpoint of exhibiting low heat build-up, the volume average particle diameter is preferably 300 μm or less, more preferably 150 μm or less, and particularly preferably 75 μm or less.

The volume average particle diameter can be determined as a particle diameter corresponding to 50% of the cumulative distribution curve in the volume-based particle size distribution using a particle size distribution measuring apparatus based on a laser diffraction method or the like.

In addition, from the viewpoint of handling during processing and reducing ignition or explosion risk, a product obtained by surface-treating a powder with oil, resin, stearic acid, or the like may be used, or the powder may be mixed with a filler such as calcium carbonate or silica.

Carbon black

Carbon black is blended in the rubber composition of the present invention. The rubber composition of the present invention contains carbon black, whereby the abrasion resistance can be improved.

The Carbon black is not particularly limited, and examples thereof include commercially available Carbon black and Carbon-silicon Dual phase filler (Carbon-silicon Dual phase filler).

Specific examples of the carbon black include SAF, ISAF, IISAF, N110, N134, N220, N234, N330, N339, N375, N550, HAF, FEF, GPF, and SRF grades of high, medium, or low structure. Among these, preferable carbon black is SAF, ISAF, IISAF, N134, N234, N330, N339, N375, HAF, or FEF grade carbon black.

The nitrogen adsorption specific surface area (N2SA, measured in accordance with JIS K6217-2: 2001) of the carbon black is preferably 50 to 160m²(ii) in terms of/g. The nitrogen adsorption specific surface area of the carbon black is more preferably 60 to 140m²(ii) g, more preferably 80 to 135m²/g。

The DBP absorption of the carbon black is not particularly limited, but is preferably 60 to 200cm³100g, more preferably 70 to 180cm³100g or more, particularly preferably 80 to 160cm³/100g。

By blending the tetrazine compound (1) in the rubber composition blended with carbon black, the dispersibility of carbon black can be greatly improved, and the low heat buildup of the rubber composition can be remarkably improved.

The carbon black is added in an amount of 30 to 120 parts by mass per 100 parts by mass of the rubber component. The amount of carbon black blended is preferably 35 to 80 parts by mass, more preferably 40 to 70 parts by mass, per 100 parts by mass of the rubber component.

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

The amount of the inorganic filler is usually 0 to 100 parts by mass, preferably 0 to 60 parts by mass, and more preferably 0 to 40 parts by mass, based on 100 parts by mass of the rubber component.

In the rubber composition of the present invention, the carbon black and the inorganic filler may be appropriately adjusted within the range of the above-mentioned blending amount of each component in the following manner: the amount of the both components is, for example, usually 30 to 150 parts by mass, preferably 35 to 130 parts by mass, and more preferably 40 to 100 parts by mass based on 100 parts by mass of the rubber component.

The total amount of carbon black and inorganic filler is preferably 30 parts by mass or more from the viewpoint of improving the abrasion resistance of the rubber composition, and is preferably 150 parts by mass or less from the viewpoint of reducing the rolling resistance. When carbon black and an inorganic filler are blended, a master batch polymer obtained by mixing a polymer in advance by wet or dry blending may be used.

Inorganic filler

The inorganic filler is not particularly limited, and may be any inorganic compound that is generally used in the rubber industry. Examples of the inorganic compound that can be used include dioxygenAlumina (Al) such as silicon oxide, gamma-alumina, alpha-alumina₂O₃) (ii) a Aluminum oxide monohydrate (Al) such as boehmite and diaspore₂O₃·H₂O); aluminum hydroxide [ Al (OH) ] such as gibbsite and bayerite₃](ii) a Aluminum carbonate [ Al ]₂(CO₃)₃]Magnesium hydroxide [ Mg (OH) ]₂]Magnesium oxide (MgO), magnesium carbonate (MgCO)₃) Talc (3 MgO.4SiO)₂·H₂O), attapulgite (5 MgO.8SiO)₂·9H₂O), titanium white (TiO)₂) Titanium black (TiO)_2n-₁) Calcium oxide (CaO), calcium hydroxide [ Ca (OH) ]₂]Aluminum magnesium oxide (MgO. Al)₂O₃) Clay (Al)₂O₃·2SiO₂) Kaolin (Al)₂O₃·2SiO₂·2H₂O), pyrophyllite (Al)₂O₃·4SiO₂·H₂O), bentonite (Al)₂O₃·4SiO₂·2H₂O), aluminum silicate (Al)₂SiO₅、Al₄·3SiO₄·5H₂O, etc.), magnesium silicate (Mg)₂SiO₄、MgSiO₃Etc.), calcium silicate (Ca)₂·SiO₄Etc.), calcium aluminum silicate (Al)₂O₃·CaO·2SiO₂Etc.), calcium magnesium silicate (CaMgSiO)₄) Calcium carbonate (CaCO)₃) Zirconium oxide (ZrO)₂) Zirconium hydroxide [ ZrO (OH) ]₂·nH₂O]Zirconium carbonate [ Zr (CO) ]₃)₂]Crystalline aluminosilicates such as various zeolites containing hydrogen for charge compensation and alkali metal or alkaline earth metal. These inorganic fillers may be subjected to organic treatment on the surface thereof in order to improve the affinity with the rubber component.

Silica is preferably added to impart strength to the rubber. As the silica, all commercially available silicas can be used. Among these, preferred silica is wet silica, dry silica, or colloidal silica, and more preferred is wet silica. In order to improve the affinity with the rubber component, the surface of the inorganic filler may be subjected to organic treatment.

Among these, silica is preferred as the inorganic filler from the viewpoint of abrasion resistance. The BET specific surface area of the silica is not particularly limited, and examples thereof include 40 to 350m²(ii) a range of/g. Silica having a BET specific surface area within the above range has an advantage that both rubber reinforcement and dispersibility in a rubber component can be achieved. The BET specific surface area can be determined in accordance with ISO 5794/1.

From this viewpoint, the preferable silica has a BET specific surface area of 50 to 250m²Silica in the range of/g, more preferably having a BET specific surface area of 100 to 230m²A silica having a BET specific surface area of 110 to 210m is particularly preferred²Silica in the range of/g.

Examples of commercially available products of such silica include "HD 165 MP" (BET specific surface area 165 m) manufactured by Quechen Silicon Chemical co., ltd²(g) 'HD 115 MP' (BET specific surface area 115 m)²(g) 'HD 200 MP' (BET specific surface area 200 m)²(g), "HD 250 MP" (BET specific surface area 250 m)²(g) 'Nipsil AQ' (BET specific surface area 205 m) manufactured by Tosoh silicon Corporation²(g) 'Nipsil KQ' (BET specific surface area 240 m)²(g); trade name "Ultrasil VN 3" manufactured by Degussa AG (BET specific surface area 175 m)²(g); trade name "Z1085 Gr" (BET specific surface area: 90 m) manufactured by Solvay²(g) 'Z Premium200 MP' (BET specific surface area 215 m)²(g) 'Z HRS 1200 MP' (BET specific surface area 200 m)²,/g), etc.

The 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, per 100 parts by mass of the rubber component.

Other compounding ingredients

In addition to the tetrazine compound (1), carbon black and inorganic filler, compounding agents generally used in the rubber industry, for example, vulcanizing agents such as sulfur, may be blended in the rubber composition of the present invention. The rubber composition of the present invention may further contain other compounding agents, for example, an antioxidant, an antiozonant, a softener, a processing aid, a wax, a resin, a foaming agent, an oil, stearic acid, zinc white (ZnO), a vulcanization accelerator, a vulcanization retarder, and the like. These compounding agents may be appropriately selected and compounded within a range not interfering with the object of the present invention. Commercially available products can be suitably used as these compounding agents.

Further, a silane coupling agent may be blended in a rubber composition blended with an inorganic filler such as silica for the purpose of enhancing the reinforcing property of the silica-based rubber composition or for the purpose of enhancing the low heat generation property and the abrasion resistance of the rubber composition.

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

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

Examples of the thioester-based silane coupling agent include 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltriethoxysilane, 3-lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane, 3-hexanoylthiopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2-octanoylthioethyltrimethoxysilane, 3-octanoylthioethyltriethoxysilane, 3-octanoylthioethyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-octanoylthioethyltrimethoxysilane, 3-octanoylthioethyltriethoxysilane, 3-octanoylthioethyltrimethoxysilane, and the like, 2-decanoylthioethyltrimethoxysilane, 2-lauroylthioethyltrimethoxysilane and the like.

Examples of the thiol-based silane coupling agent include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and 3- [ ethoxybis (3, 6, 9, 12, 15-pentaoxaoctacosan-1-yloxy) silyl ] -1-propanethiol.

Examples of the olefinic silane coupling agent include dimethoxymethylvinylsilane, vinyltrimethoxysilane, dimethylethoxyvinylsilane, diethoxymethylvinylsilane, triethoxyvinylsilane, vinyltris (2-methoxyethoxy) silane, allyltrimethoxysilane, allyltriethoxysilane, p-vinyltrimethoxysilane, 3- (dimethoxymethylsilyl) propyl acrylate, 3- (trimethoxysilyl) propyl acrylate, 3- [ dimethoxy (meth) silyl ] propyl methacrylate, 3- (trimethoxysilyl) propyl methacrylate, 3- [ dimethoxy (meth) silyl ] propyl methacrylate, 3- (triethoxysilyl) propyl methacrylate, and the like, 3- [ tris (trimethylsiloxy) silyl ] propyl methacrylate, and the like.

Examples of the epoxy-based silane coupling agent include 3-glycidoxypropyl (dimethoxy) methylsilane, 3-glycidoxypropyltrimethoxysilane, diethoxy (3-glycidoxypropyl) methylsilane, triethoxy (3-glycidoxypropyl) 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, 3-aminopropyltriethoxysilane, 3-ethoxysilyl-N- (1, 3-dimethylbutylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and N- (vinylbenzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane. Of these, 3-aminopropyltriethoxysilane is preferable.

Examples of the alkyl-based silane coupling agent include methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, 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-pentaoxaoctacosan-1-yloxy) silyl ] -1-propanethiol can be particularly preferably used.

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

The amount of the silane coupling agent blended 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, per 100 parts by mass of the inorganic filler. This is because, when the amount is 0.1 part 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 economical efficiency is improved.

In addition, in the case where the braking characteristics are particularly important, a resin or the like may be added. Specifically, there may be mentioned resins such as natural resins including rosin-based resins and terpene-based resins, petroleum-based resins, phenol-based resins, coal-based resins, and xylene-based resins. Examples of the rosin-based resin include resins such as gum rosin (gum rosin), tall oil rosin (tall oil rosin), wood rosin (wood rosin), hydrogenated rosin, disproportionated rosin (disproportated rosin), polymerized rosin, glycerin of modified rosin, and pentaerythritol ester, and examples of the terpene-based resin include terpene resins such as α -pinene, β -pinene, and dipentene, aromatic modified terpene resins, terpene phenolic resins, and hydrogenated terpene resins.

When importance is attached to processability, examples of the processing aid include mineral oil, petrolatum, paraffin, petroleum resin, fatty acid ester, fatty alcohol, metal soap, fatty acid amide, phenol resin, polyethylene, polybutene, peptizer, regenerant, and processing aids such as organosiloxane.

In addition, oil or the like may be added for adjusting the hardness. Process oils, vegetable fats, or mixtures thereof may be used. As the process oil, for example, paraffin-based process oil, aromatic-based process oil, naphthene-based process oil, and the like can be used. Examples of the vegetable oil and fat include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice bran oil, safflower oil, sesame oil, olive oil, sunflower seed oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, tung oil, and the like. Among these, paraffin-based process oils and aromatic-based process oils can be suitably used for the reason that 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 portion of a tire. Among them, a tread portion of a heavy load tire such as a tire and a truck is preferably used.

Method for producing rubber composition

The method for producing the rubber composition of the present invention is not particularly limited. The method for producing the rubber composition of the present invention includes, for example, a step (I) of kneading raw material components including a rubber component, a tetrazine compound (1), carbon black, and, if necessary, an inorganic filler, and a step (II) of kneading the mixture obtained in the step (I) and a vulcanizing agent.

Process (I)

The step (I) is a step of kneading raw material components including a rubber component, the tetrazine compound (1), carbon black, and, if necessary, an inorganic filler, and is a step before compounding a vulcanizing agent.

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

Examples of the kneading method in the step (I) include: a method of kneading a composition comprising a rubber component, a tetrazine compound (1), carbon black, and, if necessary, an inorganic filler. In this kneading method, the whole amount of each component may be kneaded at once, or each component may be added in portions and kneaded according to the purpose of viscosity adjustment or the like. Further, the tetrazine compound (1) may be added and kneaded after the rubber component and the carbon black are kneaded, or the carbon black may be added and kneaded after the rubber component and the tetrazine compound (1) are kneaded. In the step (I), the kneading may be repeated a plurality of times. When an inorganic filler is blended, the inorganic filler may be added together with carbon black and kneaded.

The temperature at the time of mixing the rubber composition in the step (I) is not particularly limited, and for example, the upper limit of the temperature of the rubber composition is preferably 120 to 190 ℃, more preferably 130 to 175 ℃, and still more preferably 140 to 170 ℃.

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

In the step (I), 0.1 to 10 parts by mass of the tetrazine compound (1) is added to 100 parts by mass of the rubber component. The amount of the tetrazine compound (1) is preferably 0.25 to 5 parts by mass, more preferably 0.5 to 2 parts by mass, per 100 parts by mass of the rubber component.

In the step (I), 30 to 120 parts by mass of carbon black is blended per 100 parts by mass of the rubber component. The amount of carbon black is preferably 35 to 80 parts by mass, more preferably 40 to 70 parts by mass, per 100 parts by mass of the rubber component.

When the rubber composition contains an inorganic filler, the amount of the inorganic filler in the step (I) is usually 20 to 150 parts by mass, preferably 35 to 120 parts by mass, and more preferably 40 to 90 parts by mass, per 100 parts by mass of the rubber component.

In the step (I), the carbon black and the inorganic filler may be appropriately adjusted within the range of the above-mentioned blending amount of each component in the following manner: the amount of the rubber component is usually 30 to 150 parts by mass based on 100 parts by mass of the rubber component.

Other examples of the kneading method in the step (I) include a two-stage kneading method comprising a step (I-1) of kneading a rubber component and a tetrazine compound (1) and a step (I-2) of kneading the mixture (modified polymer) obtained in the step (I-1), carbon black and, if necessary, an inorganic filler.

In the step (I-1), as a method of kneading the rubber component and the tetrazine compound (1), when the rubber component is a solid, a method of kneading the rubber component and the tetrazine compound (1) (kneading method) may be mentioned; when the rubber component is in a liquid state (liquid), a method of mixing a solution or emulsion (suspension) of the rubber component with the tetrazine compound (1) (liquid mixing method) and the like can be mentioned.

The kneading temperature is not particularly limited, and for example, in the case of the above kneading method, the upper limit of the temperature of the rubber component is preferably 80 to 190 ℃, more preferably 90 to 160 ℃, and further preferably 100 to 150 ℃. In the case of the liquid mixing method, the upper limit of the temperature of the rubber component is preferably 80 to 170 ℃, more preferably 90 to 160 ℃, and still more preferably 100 to 150 ℃.

The mixing time or the kneading time is not particularly limited, and for example, in the case of a kneading method, it is preferably 10 seconds to 20 minutes, more preferably 30 seconds to 10 minutes, and further preferably 60 seconds to 7 minutes. In the case of the liquid mixing method, it is preferably 10 seconds to 60 minutes, more preferably 30 seconds to 40 minutes, and still more preferably 60 seconds to 30 minutes. After the mixing reaction by the liquid mixing method, the solvent in the mixture is purged (removed) under reduced pressure, for example, to recover the solid rubber composition.

In the step (I-1), 0.1 to 10 parts by mass of the tetrazine compound (1) is added to 100 parts by mass of the rubber component. The amount of the tetrazine compound (1) is preferably 0.25 to 5 parts by mass, more preferably 0.5 to 2 parts by mass, per 100 parts by mass of the rubber component.

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.

The temperature at which the mixture (modified polymer) obtained in the step (I-1) in the step (I-2) is mixed with carbon black is not particularly limited, and for example, the upper limit of the temperature of the mixture is preferably 120 to 190 ℃, more preferably 130 to 175 ℃, and still more preferably 140 to 170 ℃.

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 still more preferably 2 minutes to 7 minutes.

The amount of carbon black blended in the step (I-2) is 30 to 120 parts by mass per 100 parts by mass of the mixture (modified polymer) obtained in the step (I-1). The amount of carbon black is preferably 35 to 80 parts by mass, and more preferably 40 to 70 parts by mass, based on 100 parts by mass of the mixture (modified polymer) obtained in the step (I-1).

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

When the inorganic filler is blended in the step (I-2), the carbon black and the inorganic filler may be appropriately adjusted within the range of the blending amount of each component as follows: the amount of the both components is usually 35 to 150 parts by mass based on 100 parts by mass of the mixture (modified polymer) obtained in the step (I-1), for example.

In the step (I), the double bond portion of the rubber component (diene rubber) reacts with the tetrazine compound (1) to form a modified polymer, and a mixture in which carbon black and, in some cases, an inorganic filler are suitably dispersed can be obtained.

Process (II)

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

In the step (II), a vulcanization accelerator or the like may be further added as required.

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

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

When the step (I) is carried out to the step (II), it is preferable to carry out the next step (II) after the temperature is reduced by 30 ℃ or more after the step (I) in the previous step is completed.

In the method for producing the rubber composition of the present invention, various compounding agents such as a vulcanization accelerator such as stearic acid and zinc white, and an antioxidant, which can be usually compounded in the rubber composition, may be added in the step (I) or the step (II) as necessary.

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

The rubber composition of the present invention includes both of the following rubber compositions: a composition containing a rubber component, a tetrazine compound (1), carbon black, and, if necessary, an inorganic filler; and a modified polymer obtained by treating a diene rubber in the rubber component with a tetrazine compound (1), carbon black, and optionally an inorganic filler.

The modified polymer formed in step (I) or (I-1) can be produced by carrying out reactions shown in the following reaction formulae-1 to-4.

[ chemical formula 4]

Reaction formula-1

[ in the formula, X¹And X²As described above.]

In the reaction formula-1, the double bond site of the diene rubber represented by the formula (A-1) reacts with the anti-electron-requiring Aza-Diels-Alder of the tetrazine compound (1) to form a bicyclo ring structure represented by the formula (B-1). the-N ═ N-moiety in the bicyclo ring structure is easily denitrified to form a six-membered ring structure represented by formula (C-1), (C-2) or (C-3), and the modified polymer having a six-membered ring structure represented by formula (2-1) can be produced by further oxidation with oxygen in the air.

[ chemical formula 5]

Reaction formula-2

[ in the formula, X¹And X²As described above.]

In reaction formula-2, in the same manner as in reaction formula-1, the double bond site of the diene rubber represented by formula (A-2) and the tetrazine compound (1) form a bicyclo ring structure represented by formula (B-2) or (B-2'), then form a six-membered ring structure represented by formulae (C-4) to (C-9), and then produce a modified polymer having the six-membered ring structure represented by formula (2-2) or (2-3).

[ chemical formula 6]

Reaction formula-3

[ in the formula, X¹And X²As described above. R represents an alkyl group or a halogen atom.]

In reaction formula-3, the double bond site of the diene rubber represented by formula (A-3) is reacted with the anti-electron-requiring Aza-Diels-Alder of tetrazine compound (1) to form a bicyclo ring structure represented by formula (B-3) or (B-3'), followed by denitrogenation to produce a modified polymer having a six-membered ring structure represented by formulae (2-4) to (2-7). When R at the double bond site of the diene rubber represented by the formula (a-3) is a halogen atom, the halogen atom may be eliminated, and in this case, a modified polymer having a six-membered ring structure represented by the formula (2-1) can be produced by an oxidation reaction.

[ chemical formula 7]

Reaction formula-4

[ in the formula, X¹、X²And R is the same as above.]

In reaction formula-4, in the same manner as in the reaction formula-3, the double bond site of the diene rubber represented by formula (A-4) is reacted with the tetrazine compound (1) to form a bicyclo ring structure represented by formula (B-4) or (B-4'), and then a modified polymer having a six-membered ring structure represented by formulae (2-8) to (2-11) is produced.

The modified polymer produced as described above has a hetero atom such as a nitrogen atom, which strongly interacts with the inorganic filler (particularly silica) and carbon black, and therefore, the dispersibility in the rubber composition can be improved, and high low heat buildup and abrasion resistance can be imparted.

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

[ chemical formula 8]

[ in the formula, X¹、X²And R is the same as above.]

3. Tyre for vehicle wheels

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 pneumatic tires (radial tires, bias tires, and the like), solid tires, and the like.

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

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

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

Among these, one preferable embodiment is a method of forming a tire tread portion of a pneumatic tire from the rubber composition.

The tire tread portion refers to a portion having a tread pattern and directly contacting a road surface, is a skin portion of the tire that protects not only a carcass but also abrasion and a trauma, and refers to a crown portion constituting a land portion of the tire and/or a tread base portion provided inside the crown portion.

The sidewall portion refers to, for example, a portion from the lower side of a shoulder portion to a bead portion in a pneumatic radial tire, and is a portion that protects a carcass and is most strongly bent when running.

The bead region is a portion that fixes both ends of the carcass cord and also plays a role of fixing the tire to the rim. The bead means a structure bundled with high carbon steel.

The belt portion means a reinforcing belt extending in the circumferential direction between the tread and the carcass of the radial structure. Tightening the carcass as tightly as the hoops of the drum increases the rigidity of the tread.

The carcass portion is a portion forming a cord layer of a tire frame, and functions to withstand a load, an impact, and inflation pressure applied to the tire.

The shoulder portion is a shoulder portion of the tire, and plays a role of protecting the carcass.

The tire of the present invention may be manufactured according to methods currently known in the art of tires.

As the gas to be filled into the tire, air having a normal or adjusted oxygen partial pressure; inert gases such as nitrogen, argon, helium, and the like.

Examples

The present invention will be specifically described below with reference to production examples and examples. However, the embodiments are merely examples, and the present invention is not limited to the embodiments.

Production example 1: production of 3, 6-bis (3-pyridyl) -1, 2, 4, 5-tetrazine (1a)

To a 200mL four-necked flask were added 24g (0.23 mol) of 3-cyanopyridine, 15g (1.3 equiv) of hydrazine hydrate, and 48mL of methanol, and the mixture was stirred at room temperature. Next, 3.6g (15 wt%) of sulfur was added to the mixture, and a reflux tube was installed and heated and stirred at an external temperature of 70 ℃ overnight. The reaction solution was cooled with ice, filtered, crystallized, and washed with a small amount of cold methanol. The crude crystals were dried under reduced pressure to give 19g of an orange crude dihydrotetrazine.

17.8g of the obtained crude crystal was dissolved in 178g (40 equivalents) of acetic acid, and sulfur was removed by filtration. A dihydrotetrazine acetic acid solution and 178mL of distilled water were added to a 1L four-necked eggplant type flask, and the mixture was stirred under ice cooling. Sodium nitrite (15.5 g, 3 equivalents) was added to 35mL of distilled water, and the resulting solution was 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 a 10% aqueous solution of sodium hydrogencarbonate to give crude crystals. The crude crystals were purified by silica gel column (ethyl acetate) to obtain 8.4g (magenta, needle-like crystals) of the title tetrazine compound (1 a).

Melting point: at a temperature of 200c,

¹H-NMR(300MHz，CDCl₃，δppm)：

7.59(ddd，J＝0.9，5.1，7.8Hz，2H)，8.89-8.96(m，4H)，9.88(dd，J＝0.9，2.4Hz，2H)

examples 1 to 6 and comparative examples 1 to 6

The components described in step (I) in tables 1 and 2 below were mixed in the proportions (parts by mass) and kneaded for 5 minutes while adjusting the rotation speed so that the maximum temperature of the mixture became 160 ℃. Curing was performed until the temperature of the mixture became 80 ℃ or lower, and then, the respective components described in step (II) in tables 1 and 2 were charged in the proportions (parts by mass) thereof, and kneaded while adjusting so that the maximum temperature of the mixture became 110 ℃ or lower, to produce respective rubber compositions.

Abrasion resistance test

The rubber compositions (test compositions) prepared in examples 1 to 6 and comparative examples 1 to 6 were subjected to a Lambourn abrasion test (JIS K6264) at room temperature under the condition that the slip ratio (slip rate) was 24%. The abrasion resistance index was calculated based on the following formula using the rubber composition prepared in comparative example 1 as a reference.

The results are shown in tables 1 and 2.

Formula (II):

abrasion resistance index { (abrasion amount of reference)/(abrasion amount of test composition) } × 100

Low Heat buildup (tan. delta. index) test

The rubber compositions (test compositions) prepared in examples 1 to 6 and comparative examples 1 to 6 were measured for tan δ using a viscoelasticity measuring apparatus (manufactured by Metravib) under conditions of a temperature of 40 ℃, a dynamic strain of 5%, and a frequency of 15 Hz.

The low heat buildup index was calculated based on the following formula using the rubber composition prepared in comparative example 1 as a reference.

The larger the value of the low heat buildup index is, the lower the heat buildup is, and the smaller the hysteresis loss is. Further, the low heat buildup of the reference vulcanized rubber composition was taken as 100.

The results are shown in tables 1 and 2.

Formula (II):

low heat buildup index { (tan. delta. as reference)/(tan. delta. as test composition) } × 100

[ Table 1]

[ Table 2]

[ description of symbols in the tables ]

The raw materials used in tables 1 and 2 are shown below.

In addition, the method is as follows: variety "SB R1502", manufactured by JSR Kabushiki Kaisha "

In addition, 2: product name "BR 150B" made by Udo Kyoho K.K. "

And (2) in color: manufactured by Zhonghua International corporation, trade name "RSS # 3"

In addition, 4: tokai Carbon Co., Ltd., product name "Seast 6" (nitrogen adsorption specific surface area 119 m)²/g)

※5：Tokai Carbon Co., Ltd., product name "Seast 3" (nitrogen adsorption specific surface area 79 m)²/g)

In addition, 6: product name "Antage 6C" manufactured by Kayokoku industries Ltd "

In addition, the color is 7: "1 species" of zinc oxide of Sakai Chemical Industry Co., Ltd "

In addition, the color is 8: sichuan Tianyu great Chemical Co., Ltd

In addition, the color is 9: manufactured by Japan wax Seiko, trade name "OZOACE-0355"

In addition, the color is 10: JXJXTG Nippon Oil & Energy Corporation, trade name "X-140 (aromatic Oil)"

The method is characterized in that: 3, 6-bis (3-pyridyl) -1, 2, 4, 5-tetrazine (compound produced in production example 1)

The crude product was 12: 3, 6-bis (2-pyridyl) -1, 2, 4, 5-tetrazine manufactured by Tokyo Kasei Kogyo Co., Ltd

The crude product was 13: 3, 6-bis (4-pyridyl) -1, 2, 4, 5-tetrazine manufactured by Tokyo Kasei Kogyo Co., Ltd

The color is 14: manufactured by Mitsui chemical industries, Ltd., trade name "HK 200-5"

In addition, 15 is in color: product name "Nocceler CZ-G" from Dainippon chemical industries Co., Ltd "

The color is 16: trade name "CTP" manufactured by Dainixing chemical industries, Ltd "

Industrial applicability

The rubber composition of the present invention is excellent in both abrasion resistance and low heat buildup, and therefore, when the rubber composition is used, it is possible to produce various pneumatic tires for automobiles, particularly tread portions (tire treads) of high-load tires.

Claims

1. A rubber composition comprising a rubber component, a tetrazine compound represented by the following general formula (1) or a salt thereof, and carbon black,

[ chemical formula 1]

In the formula, X¹And X²Represents a heterocyclic group which may have a substituent;

2. The rubber composition according to claim 1, wherein the carbon black has a nitrogen adsorption specific surface area of 50 to 160m²/g。

3. A tread for a tire, which is produced using the rubber composition according to claim 1 or 2.

4. A pneumatic tire using the tread for tire of claim 3.

5. The tire according to claim 4, which is used for a heavy load tire for a large automobile.