JP6812289B2 - Rubber composition and tires - Google Patents

Description

The present invention relates to rubber compositions and tires.

In recent years, due to consideration for the environment, carbon dioxide emission regulations have become stricter worldwide, and the demand for fuel efficiency of automobiles has increased significantly. The efficiency of the drive system such as the engine and the transmission system contributes greatly to the fuel efficiency, but the rolling resistance of the tire is also greatly involved, and it is important to reduce the rolling resistance to reduce the fuel efficiency of the automobile. ..

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

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

However, even if the rubber compositions of Patent Documents 1 to 5 are used, the improvement of low heat generation is insufficient. Further, by improving the rolling resistance of the rubber composition, it is unavoidable that the braking performance and steering stability of the tire on a wet road surface are lowered.

The demand for fuel efficiency of automobiles is increasing, and the development of tires with extremely low rolling resistance is eagerly desired.

Japanese Unexamined Patent Publication No. 2003-514079 Special Table 2003-523472 Japanese Unexamined Patent Publication No. 2013-108004 Japanese Unexamined Patent Publication No. 2000-169631 JP-A-2005-220323

An object of the present invention is to provide a rubber composition capable of exhibiting low rolling resistance while maintaining the braking performance and steering stability of a tire.

Another object of the present invention is to provide a tire having excellent low rolling resistance while maintaining braking performance and steering stability.

As a result of diligent studies to solve the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by preparing a rubber composition containing a rubber component containing a specific diene-based rubber and a tetrazine-based compound. I found it. The present inventors have completed the present invention as a result of further studies based on such findings.

The present invention provides the rubber composition, tire, etc. shown below.
Item 1.
A rubber composition containing a rubber component and a filler.
In 100 parts by mass of the rubber component, the main chain of the diene rubber is modified with a substituted pyridazine group, and 30 to 100 parts by mass of the modified rubber containing the substituted pyridazine group in one molecule of the diene rubber on average of 2 or more is contained. ,
Contains 35 to 150 parts by mass of filler with respect to 100 parts by mass of rubber component.
The loss tangent (tan δ) of the rubber composition measured at 0 ° C. and 1% strain is 0.25 to 1.3, and the tan δ measured at 60 ° C. and 5% strain is 0.05 to 0.35. A rubber composition having a storage elastic modulus (G') of 0.2 to 7 MPa as measured at 25 ° C. and 5% strain.
Item 2.
Item 2. The rubber composition according to Item 1, wherein the substituted pyridazine group is a pyridazine group substituted with a heterocyclic group.
Item 3.
Item 2. The rubber composition according to Item 1 or 2, wherein the substituted pyridazine group is formed by the reaction of the substituted tetrazazine compound with the double bond of the diene rubber contained in the rubber component.
Item 4.
Item 3. The rubber composition according to Item 3, wherein the reaction between the substituted tetrazine compound and the diene rubber occurs in a rubber kneading mixer in the range of 80 to 180 ° C.
Item 5.
Item ^2. The rubber composition according to any one of Items 1 to 4, wherein the wet silica having a BET specific surface area in the range of 50 to 240 m ² / g is contained in an amount of 25 to 130 parts by mass with respect to 100 parts by mass of the rubber component.
Item 6.
Item 6. The rubber composition according to any one of Items 1 to 5 used for the tread portion.
Item 7.
A tire tread produced by using the rubber composition according to any one of Items 1 to 5.
Item 8.
A pneumatic tire using the tire tread according to Item 7.

According to the present invention, a specific amount of a modified rubber and a filler obtained by reacting a specific substituted tetrazine compound with a diene rubber is blended, and the characteristics of the rubber composition (loss tangent and storage elastic modulus) are set to specific values. By setting, it is possible to provide a rubber composition capable of exhibiting low rolling resistance while maintaining the braking performance and steering stability of the tire.

Further, by producing a tire tread using the rubber composition of the present invention, it is possible to reduce the rolling resistance of the tire and the heat generation of the tire, and to improve braking performance and steering stability on a wet road surface. It is possible to provide excellent tires.

The present invention will be described in detail below.

1. 1. Rubber Composition In the rubber composition of the present invention, the main chain of the diene-based rubber is modified with a substituted pyridazine group in 100 parts by mass of the rubber component, and an average of two substituted pyridazine groups are contained in one molecule of the diene-based rubber. It contains 30 to 100 parts by mass of the modified rubber containing the above, and contains 35 to 150 parts by mass of the filler with respect to 100 parts by mass of the rubber component.

In the rubber composition of the present invention, the loss tangent (tan δ) measured at 0 ° C. and 1% strain is 0.25 to 1.3, and the tan δ measured at 60 ° C. and 5% strain is 0.05 to 0. The storage elastic modulus (G') measured at 35 and at 25 ° C. and 5% strain is 0.2 to 7 MPa.

Rubber component The rubber component blended in the rubber composition of the present invention is not particularly limited, and is, for example, a diene-based rubber such as natural rubber (NR), synthetic diene-based rubber, and a mixture of natural rubber and synthetic diene-based rubber. Examples include rubber and other non-diene rubbers.

Natural rubber includes natural rubber latex, technical rating rubber (TSR), smoked sheet (RSS), rattling, Tochu-derived natural rubber, Guayur-derived natural rubber, Russian dandelion-derived natural rubber, and plant-based fermented rubber. In addition, modified natural rubber such as epoxidized natural rubber, methacrylic acid modified natural rubber, and styrene modified natural rubber can be mentioned.

Examples of synthetic diene rubbers include styrene-butadiene copolymer rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), nitrile rubber (NBR), chloroprene rubber (CR), and ethylene-propylene-diene ternary products. Examples thereof include polymer rubber (EPDM), styrene-isoprene-styrene ternary block copolymer (SIS), styrene-butadiene-styrene ternary block copolymer (SBS), and modified synthetic diene rubbers thereof. Examples of the modified synthetic diene rubber include diene rubber produced by a modification method such as main chain modification, single-ended modification, and double-ended modification. Here, the modified functional group of the modified synthetic diene rubber includes one or more functional groups containing heteroatoms 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 can be mentioned. The ratio of cis / trans / vinyl in the diene portion is not particularly limited, and any ratio can be preferably used. The average molecular weight and molecular weight distribution of the diene rubber are not particularly limited, and an average molecular weight of 5 to 3 million and a molecular weight distribution of 1.5 to 15 are preferable. The method for producing the synthetic diene-based rubber is also not particularly limited, and examples thereof include those synthesized by emulsion polymerization, solution polymerization, radical polymerization, anionic polymerization, cationic polymerization and the like.

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

In the rubber component used in the rubber composition of the present invention, the main chain of the diene rubber is modified with a substituted pyridazine group from the viewpoint of rolling resistance, and the substituted pyridazine group is averaged 2 in one molecule of the diene rubber. It is preferable to include modified rubber containing more than one (hereinafter, also referred to as "modified rubber").

The modified rubber is a reaction product of a substituted tetrazine compound and a diene-based rubber, and the substituted pyridazine group is formed by a reaction of a double bond between the substituted tetrazine compound and the diene-based rubber.

Raw materials for producing modified rubbers include diene-based rubbers and substituted tetrazine compounds. The rubber component used as a raw material may include rubber other than the diene rubber in addition to the diene rubber. The diene rubber is, for example, preferably contained in an amount of 70 parts by mass or more, more preferably 80 parts by mass or more, and 100 parts by mass is a diene rubber in 100 parts by mass of the rubber component used. Is more preferable.

As the diene-based rubber, the diene-based rubbers listed in the above rubber components can be used alone or in combination of two or more.

As the diene-based rubber, a rubber obtained by polymerizing a natural rubber, an isoprene rubber, and a monomer containing a 1,3-butadiene monomer is preferable. Examples of the rubber obtained by polymerizing the monomer containing the 1,3-butadiene monomer include SBR, BR, NBR and the like, and SBR and BR are preferable.

Among them, the preferable diene rubber is natural rubber, IR, SBR, BR or a mixture of two or more kinds selected from these, and more preferably natural rubber, SBR, BR or a mixture of two or more kinds selected from these. is there. Further, the blend ratio thereof is preferably 70 to 100 parts by mass of SBR, BR or a mixture thereof in 100 parts by mass of the rubber component containing the diene rubber, and 75 to 100 parts by mass. It is particularly preferable to do so. When blending a mixture of SBR and BR, the total amount of SBR and BR is preferably in the above range. Further, the SBR at this time is 50 to 100 parts by mass, and the BR is preferably in the range of 0 to 50 parts by mass.

Examples of the substituted tetrazine compound include a compound represented by the following general formula (1) or a salt thereof (hereinafter, may be referred to as “substituted tetrazine compound (1))).
General formula (1):

[In the formula, X ¹ and X ² represent heterocyclic groups that may have substituents. ]

In the present specification, the "heterocyclic group" is not particularly limited, and for example, 2-pyridyl group, 3-pyridyl group, 4-pyridyl group, 2-pyrazinyl group, 2-pyrimidyl group, 4-pyrimidyl group, and the like. 5-pyrimidyl group, 3-pyridadyl group, 4-pyridadyl group, 4- (1,2,3-triazyl) group, 5- (1,2,3-triazyl) group, 2- (1,3,5- Triasyl) group, 3- (1,2,4-triazyl) group, 5- (1,2,4-triazil) group, 6- (1,2,4-triazil) group, 2-quinolyl group, 3- Quinoline group, 4-quinolyl group, 5-quinolyl group, 6-quinolyl group, 7-quinolyl group, 8-quinolyl group, 1-isoquinolyl group, 3-isoquinolyl group, 4-isoquinolyl group, 5-isoquinolyl group, 6- Isoquinolyl group, 7-isoquinolyl group, 8-isoquinolyl group, 2-quinoxalyl group, 3-quinoxalyl group, 5-quinoxalyl group, 6-quinoxalyl group, 7-quinoxalyl group, 8-quinoxalyl group, 3-cinnolyl group, 4- Synoryl group, 5-Synolinyl group, 6-Synolyl group, 7-Synolinyl group, 8-Synolinyl group, 2-Kynazolyl group, 4-Kynazolyl group, 5-Kynazolyl group, 6-Kynazolyl group, 7-Kynazolyl group, 8- Kinazolyl group, 1-phthalazyl group, 4-phthalazyl group, 5-phthalazyl group, 6-phthalazyl group, 7-phthalazyl group, 8-phthalazyl group, 1-tetrahydroquinolyl group, 2-tetrahydroquinolyl group, 3-tetrahydro Quinoline group, 4-tetrahydroquinolyl group, 5-tetrahydroquinolyl group, 6-tetrahydroquinolyl group, 7-tetrahydroquinolyl group, 8-tetrahydroquinolyl group, 1-pyrrrolyl group, 2-pyrrolill group, 3 -Pyrrolyl group, 2-furyl group, 3-furyl group, 2-thienyl group, 3-thienyl group, 1-imidazolyl group, 2-imidazolyl group, 4-imidazolyl group, 5-imidazolyl group, 1-pyrazolyl group, 3 -Pyrazolyl group, 4-pyrazolyl group, 5-pyrazolyl group, 2-oxazolyl group, 4-oxazolyl group, 5-oxazolyl group, 2-thiazolyl group, 4-thiazolyl group, 5-thiazolyl group, 3-isooxazolyl group, 4 -Isooxazolyl group, 5-isoxazolyl group, 3-isothiazolyl group, 4-isothiazolyl group, 5-isothiazolyl group, 4- (1,2,3-thiadiazolyl) group, 5- (1,2,3-thiadiazolyl) group, 3- (1,2,5-thiazol) group, 2- (1,3,4-thiazol) Le) group, 4- (1,2,3-oxadiazolyl) group, 5- (1,2,3-oxadiazolyl) group, 3- (1,2,4-oxadiazolyl) group, 5- (1,2, 4- (1,2,5-oxadiazolyl) group, 3- (1,2,5-oxadiazolyl) group, 2- (1,3,4-oxadiazolyl) group, 1- (1,2,3-triazolyl) group, 4- (1, 2,3-Triazolyl) group, 5- (1,2,3-triazolyl) group, 1- (1,2,4-triazolyl) group, 3- (1,2,4-triazolyl) group, 5- ( 1,2,4-triazolyl) group, 1-tetrazolyl group, 5-tetrazolyl group, 1-indrill, 2-indrill group, 3-indrill group, 4-indrill group, 5-indrill group, 6-indrill group, 7 -Indrill group, 1-isoindrill group, 2-isoindrill group, 3-isoindrill group, 4-isoindrill group, 5-isoindrill group, 6-isoindrill group, 7-isoindrill group, 1-benzoimidazolyl group, 2-benzoimidazolyl group, 4 -Benomidazolyl group, 5-benzoimidazolyl group, 6-benzoimidazolyl group, 7-benzoimidazolyl group, 2-benzofuranyl group, 3-benzofuranyl group, 4-benzofuranyl group, 5-benzofuranyl group, 6-benzofuranyl group, 7-benzofuranyl group, 1 -Isobenzofuranyl group, 3-isobenzofuranyl group, 4-isobenzofuranyl group, 5-isobenzofuranyl group, 6-isobenzofuranyl group, 7-isobenzofunyl group, 2-benzothienyl group, 3-benzothienyl group, 4-benzothienyl group, 5-benzothienyl group, 6-benzothienyl group, 7-benzothienyl group, 2-benzoxazolyl group, 4-benzoxazolyl group, 5-benzoxa Zoryl group, 6-benzoxazolyl group, 7-benzoxazolyl group, 2-benzothiazolyl group, 4-benzothiazolyl group, 5-benzothiazolyl group, 6-benzothiazolyl group, 7-benzothiazolyl group, 1-indazolyl group, 3-Indazolyl group, 4-Indazolyl group, 5-Indazolyl group, 6-Indazolyl group, 7-Indazolyl group, 2-Molholyl group, 3-Morphoryl group, 4-Morphoryl group, 1-Piperazyl group, 2-Piperazyl group, 1-piperidyl group, 2-piperidyl group, 3-piperidyl group, 4-piperidyl group, 2-tetrahydropyranyl group, 3-tetrahydropyranyl group, 4-tetrahydropyranyl group, 2-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-Tetrahydrofuranyl group and the like. Among them, the preferred heterocyclic group is a pyridyl group, a furanyl group, a thienyl group, a pyrimidyl group or a pyrazil group, and more preferably a pyridyl group.

The heterocyclic group may have one or more substituents at substitutable positions. The substituent is not particularly limited, and is, for example, a halogen atom, an amino group, an aminoalkyl group, an alkoxycarbonyl group, an acyl group, an acyloxy group, an amide group, a carboxyl group, a carboxyalkyl group, a formyl group, a nitrile group, and a nitro group. Examples thereof include a 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. The substituent may preferably have 1 to 5, more preferably 1 to 3.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

A more preferable substituted tetrazine compound (1) is a 2-pyridyl group in which X ¹ and X ² are the same or different and may have a substituent, a 3-pyridyl group which may have a substituent, and the like. It may have a 4-pyridyl group which may have a substituent, a 2-furanyl group which may have a substituent, a thienyl group which may have a substituent, and a substituent 1 which may have a substituent. -A compound which is a pyrazolyl group, a 2-pyrimidyl group which may have a substituent, or a 2-pyrazyl group which may have a substituent, and specifically, a compound which has a substituent. It may be a 2-pyridyl group, a 3-pyridyl group which may have a substituent, a 4-pyridyl group which may have a substituent, or a 2-furanyl group which may have a substituent. Certain compounds are particularly preferred.

Specific examples of the substituted 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,
Examples thereof include 3,6-bis (2-pyrazyl) -1,2,4,5-tetrazine.

Among them, the preferred tetrazine compound (1) is 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- (4-pyridyl) -1,2,4,5-tetrazine, more preferred tetrazine compounds. (1) is 3,6-bis (2-pyridyl) -1,2,4,5-tetrazine, 3,6-bis (3-pyridyl) -1,2,4,5-tetrazine, and 3, 6-Bis (4-pyridyl) -1,2,4,5-tetrazine.

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

When the substituted tetrazine compound (1) is a powder, its volume average diameter is not particularly limited. From the viewpoint of developing low rolling resistance, 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 mean diameter can be obtained as a particle diameter corresponding to 50% of the integrated distribution curve from the volume reference particle size distribution by using a particle size distribution measuring device such as a laser light diffraction method.

Further, from the viewpoint of handleability during handling and reduction of ignitability or explosive risk, powder may be surface-treated with oil, resin, stearic acid, etc., or powder may be treated with calcium carbonate, silica, etc. You may use it by mixing with the filler of.

The substituted pyridazine group of the modified rubber is formed by the reaction of the substituted tetrazine compound (1) with the double bond of the diene rubber.

Specific examples of the substituted pyridazine group include structures represented by the following formulas (2-1) to (2-11).

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

In the above formulas (2-1) to (2-11), X ¹ and X ² are preferably heterocyclic groups. That is, the substituted pyridazine group is preferably a pyridazine group substituted with a heterocyclic group, and more preferably a pyridazine group substituted with a pyridine group.

An average of 2 or more, preferably 4 or more, and more preferably 5 or more of the substituted pyridazine groups are contained in one molecule of the modified rubber. The number of substituted pyridazine groups contained in one molecule of the modified rubber can be calculated by the following formula.

Number of substituted pyridazine groups in one molecule (pieces / modified rubber molecule) =
{(Number average molecular weight of diene rubber) / (Molecular weight of added substituted tetrazine compound)} × {(Number of added mass parts of added substituted tetrazine compound) / 100}

The modified rubber is modified with a substituted pyridazine group, and the substituted pyridazine group has a nitrogen atom. Since this nitrogen atom strongly interacts with the filler, it is possible to enhance the dispersibility of the filler in the diene-based rubber component, impart high low rolling resistance to the rubber composition to be blended, and brake. Performance and steering stability can be maintained.

The method for producing the modified rubber is not particularly limited. The modified rubber is produced, for example, by using a rubber component containing a diene-based rubber and a rubber mixture containing the substituted tetrazine compound (1). The modified rubber can be produced using a known rubber kneading mixer such as a Banbury mixer, a roll, an intensive mixer, a kneader, or a twin-screw extruder.

In addition, in this specification, the term "mixing" also includes the meaning of "kneading".

As a specific method for producing the modified rubber, when the rubber component containing the diene rubber is a solid, a method of mixing the rubber component with the substituted tetrazine compound (1) (solid mixing method); including the diene rubber. When the rubber component is a liquid (liquid), a method of mixing the solution or emulsion (suspension) of the rubber component with the substituted tetrazine compound (1) (liquid mixing method) and the like can be mentioned.

The mixing temperature is not particularly limited. For example, in the case of the solid mixing method, the temperature of the rubber mixture is preferably 80 to 180 ° C, more preferably 90 to 160 ° C, and 100 to 150. It is more preferably ° C. In the case of the liquid mixing method, the temperature of the liquid rubber mixture is preferably 80 to 180 ° C., more preferably 90 to 160 ° C., and even more preferably 100 to 150 ° C. The substituted pyridazine group is formed by the reaction of the substituted tetrazine compound (1) with the diene rubber in a rubber kneading mixer in the range of 80 to 180 ° C.

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

In the method for producing a modified rubber, the rubber component containing a diene-based rubber is composed of a group in which 70% by mass or more of the rubber component is polymerized with a natural rubber, isoprene rubber, and a monomer containing a 1,3-butadiene monomer. It is preferably at least one selected. The rubber component containing the diene-based rubber may contain a rubber other than the diene-based rubber. Examples of the rubber other than the diene rubber include non-diene rubber such as butyl rubber (IIR). The content of the diene rubber in the rubber component is more preferably 80% by mass or more, and further preferably 100% by mass. The blending amount of the substituted tetrazine compound (1) is not particularly limited, and is usually 0.1 to 10 parts by mass, preferably 0.25 to 10 parts by mass with respect to 100 parts by mass of the rubber component containing the diene rubber. It may be appropriately adjusted to 5 parts by mass, more preferably 0.5 to 2 parts by mass.

Here, the substituted pyridazine group is considered to be obtained by the following reaction mechanism.

Specifically, the substituted pyridazine group has six members in which the substituted hydrazine compound (1) is bound to the double bond site of the diene rubber by proceeding with the reaction as shown in the following reaction formulas -1 to 4. Manufactured by forming a ring structure.

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

In the reaction formula-1, the reverse electron request type Aza-Diels-Alder reaction between the double bond site of the diene rubber represented by the formula (A-1) and the substituted tetrazine compound (1) is carried out by the formula (B-). It forms the bicyclo ring structure represented by 1). Denitrification easily proceeds in the -N = N-part in this bicyclo ring structure, and a six-membered ring structure represented by the formula (C-1), (C-2) or (C-3) is formed. It is formed, but is further oxidized by oxygen in the air to produce a substituted pyridazine group represented by the formula (2-1).

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

In the reaction formula-2, similarly to the reaction formula-1, from the double bond site of the diene rubber represented by the formula (A-2) and the substituted tetrazine compound (1), the formula (B-2) or After forming the bicyclo ring structure represented by (B-2') and then the six-membered ring structure represented by the formulas (C-4) to (C-9), the formula (2-2) or (2-2-). The substituted pyridazine group represented by 3) is produced.

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

In the reaction formula-3, the reverse electron request type Aza-Diels-Alder reaction between the double bond site of the diene rubber represented by the formula (A-3) and the substituted tetrazine compound (1) is carried out by the formula (B-). After forming the bicyclo ring structure represented by 3) or (B-3'), the substituted pyridazine groups represented by the formulas (2-4) to (2-7) are produced by denitrification. When R on 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 that case, an oxidation reaction may occur. A substituted pyridazine group represented by the formula (2-1) is produced.

[In the formula, X ¹ , X ² , and R are the same as described 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 substituted tetrazine compound (1) is carried out by the reaction of the formula (B). After forming the bicyclo ring structure represented by -4) or (B-4'), the substituted pyridazine groups represented by the formulas (2-8) to (2-11) are produced.

As described above, the produced modified rubber has heteroatoms such as nitrogen atoms, and these heteroatoms strongly interact with the filler (particularly wet silica), so that the modified rubber is dispersed in the rubber composition. It is possible to enhance the property and impart high low rolling resistance.

In the method for producing a modified rubber, wet silica, other filler and the like may be present at the same time in addition to the rubber component and the substituted tetrazine compound (1).

In addition to the modified rubber, the rubber composition of the present invention contains a filler and, if necessary, a vulcanizing agent.

The loss tangent (tan δ) of the rubber composition measured at 0 ° C. and 1% strain is 0.25 to 1.3, preferably 0.3 to 1, and is measured at 60 ° C. and 5% strain. The tan δ is 0.05 to 0.35, preferably 0.07 to 0.3, and the storage elastic modulus (G') measured at 25 ° C. and 5% strain is 0.2 to 7 MPa, preferably 0.2 to 7 MPa. It is 0.6 to 2.5 MPa.

The loss tangent (tan δ) measured at 0 ° C. and 1% strain is tan δ measured at a temperature of 0 ° C., a dynamic strain of 1%, and a frequency of 15 Hz using a viscoelasticity measuring device (manufactured by Metravib). ..

The tan δ measured at 60 ° C. and 5% strain is a tan δ measured at a temperature of 60 ° C., a dynamic strain of 5%, and a frequency of 15 Hz using a viscoelasticity measuring device (manufactured by Metravib).

The storage elastic modulus (G') measured at 25 ° C. and 5% strain is a value measured at a temperature of 25 ° C., a dynamic strain of 5%, and a frequency of 15 Hz using a viscoelasticity measuring device (manufactured by Metravib). ..

The rubber composition of the present invention is characterized in that the loss tangent (tan δ) and the storage elastic modulus (G') of the rubber composition are in the above ranges. Braking performance on wet road surfaces by setting the loss tangent (tan δ) at 0 ° C., the loss tangent (tan δ) at 60 ° C., and the storage elastic modulus (G') at 25 ° C. of the rubber composition within the above ranges. , A rubber composition capable of exhibiting steering stability and rolling resistance performance in a well-balanced manner can be obtained.

The blending amount of the filler is usually 35 to 150 parts by mass, preferably 40 to 110 parts by mass, and more preferably 50 to 100 parts by mass with respect to 100 parts by mass of the rubber component.

As the filler, it is preferable to blend wet silica having a BET specific surface area in the range of 50 to 240 m ² / g.

By including the wet silica in the rubber composition of the present invention, braking characteristics, particularly braking performance on a wet road surface can be improved. The surface of the wet silica may be organically treated with a silane coupling agent, a surfactant, or the like in order to improve the affinity with the rubber component.

The BET specific surface area of wet silica is in the range of 50-240 m ² / g. Silica having a BET specific surface area in this range has an advantage that both rubber reinforcing properties and dispersibility in rubber components can be achieved at the same time. The BET specific surface area is measured according to ISO 5794/1.

From this point of view, the preferred wet silica is a wet silica having a BET specific surface area in the range of 100 to 230 m ² / g, and more preferably a wet silica having a BET specific surface area of 110 to 210 m ² / g.

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

The blending amount of the wet silica is usually 25 to 130 parts by mass, preferably 30 to 100 parts by mass, and more preferably 40 to 90 parts by mass with respect to 100 parts by mass of the rubber component.

Usually, the addition of silica to the rubber composition improves the steering stability performance, but the addition of a large amount tends to deteriorate the heat resistance. However, by using the modified rubber, excellent low rolling resistance is exhibited even if a large amount of the wet silica is blended. This is because the modified rubber produced by the reaction of the diene-based rubber and the substituted tetrazine compound (1) has an affinity for silica due to the presence of nitrogen atoms derived from the substituted tetrazine compound (1) contained in the substituted pyridazine group. It is considered that this is improved because the silica is further dispersed in the rubber component.

In particular, the amount of wet silica blended in order to achieve both steering stability performance and fuel efficiency is usually 30 to 120 parts by mass, preferably 60 to 115 parts by mass with respect to 100 parts by mass of the rubber component. , 70 to 110 parts by mass.

Wet silica having a BET specific surface area is less than ^{50 m} 2 / g, and wet silica BET specific surface area exceeds 240 m ² / may also be used within the range not impairing the effect of the present invention.

It is also effective to combine and blend two or more types of silica having different BET specific surface areas, such as a combination of large particle size silica and small particle size silica.

The rubber composition of the present invention may further contain a filler other than the wet silica in addition to the modified rubber, the vulcanizing agent, and the wet silica.

Examples of the filler other than the wet silica include an inorganic filler other than the wet silica, carbon black and the like. The rubber composition of the present invention preferably contains, as a filler, an inorganic filler other than the wet silica and / or carbon black as a filler other than the wet silica.

The blending amount of the wet silica and the inorganic filler other than the wet silica is usually 20 to 150 parts by mass, preferably 30 to 120 parts by mass, and more preferably 40 to 90 parts by mass with respect to 100 parts by mass of the rubber component. It is a department. When the wet silica and other inorganic filler are used in combination, the total amount of both components is, for example, 10 to 150 parts by mass with respect to 100 parts by mass of the rubber component, and the blending amount of the wet silica is usually 30. The blending amount of the inorganic filler other than the wet silica may be appropriately adjusted within the above blending amount so as to be ~ 120 parts by mass.

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

In the rubber composition of the present invention, the wet silica and the inorganic filler and / or carbon black other than the wet silica are usually 35 to 140 in the total amount of all the components, for example, with respect to 100 parts by mass of the rubber component. It may be appropriately adjusted within the above-mentioned blending amount of each component so as to be a mass portion, preferably 40 to 130 parts by mass, and more preferably 45 to 100 parts by mass.

When the total blending amount of the wet silica and the inorganic filler other than the wet silica and / or carbon black is 35 parts by mass or more, it is preferable from the viewpoint of steering stability of the rubber composition, and when it is 140 parts by mass or less. , Preferable from the viewpoint of reducing rolling resistance. When blending wet silica and an inorganic filler other than wet silica and / or carbon black, a masterbatch polymer previously mixed with a diene rubber in a wet or dry manner 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 the inorganic compounds that can be used include silica other than the wet silica, alumina such as γ-alumina and α-alumina (Al ₂ O ₃ ); and alumina monohydrate such as boehmite and diaspore (Al ₂ O ₃ · H). ₂ O); Aluminum hydroxide [Al (OH) ₃ ] such as gibsite and bayarite; Aluminum carbonate [Al ₂ (CO ₃ ) ₂ ], Magnesium hydroxide [Mg (OH) ₂ ], Magnesium oxide (MgO), magnesium carbonate (MgCO _3), talc _{(3MgO · 4SiO 2 · H 2} O), attapulgite _{(5MgO · 8SiO 2 · 9H 2} O), titanium white _(TiO 2), titanium black _{(TiO 2n-1),} calcium oxide ( CaO), calcium hydroxide [Ca _(OH) 2], magnesium aluminum oxide _{(MgO · Al 2 O 3)} , clay _{(Al 2 O 3 · 2SiO 2} ), kaolin _{(Al 2 O 3 · 2SiO 2} · 2H 2 O ), pyrophyllite _{(Al 2 O 3 · 4SiO 2} · H 2 O), bentonite _{(Al 2 O 3 · 4SiO 2} · 2H 2 O), aluminum silicate _{(Al 2 SiO 5, Al 4} · 3SiO 4 · 5H ₂ O etc.), Magnesium silicate (Mg ₂ SiO ₄ , MgSiO ₃ etc.), Calcium silicate (Ca ₂ · SiO ₄ etc.), Aluminum silicate (Al ₂ O ₃ · CaO · 2SiO ₂ etc.), Silica magnesium calcium (CaMgSiO _4), calcium carbonate (CaCO _3), zirconium oxide _(ZrO 2), zirconium hydroxide _{[ZrO (OH) 2 · nH} 2 O], zirconium carbonate _{[Zr (CO 3) 2]} , various zeolites Examples thereof include crystalline aluminosilicates containing hydrogen, alkali metals or alkaline earth metals for which the charge is corrected. In these inorganic fillers, the surface of the inorganic filler may be organically treated in order to improve the affinity with the rubber component.

Carbon black The carbon black is not particularly limited, and for example, commercially available carbon black, Examples thereof include Carbon-Silica Dual phase filler.

Specifically, as 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 can be mentioned. Among them, preferable carbon blacks are SAF, ISAF, IISAF, N134, N234, N330, N339, N375, HAF, or FEF grade carbon black.

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

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

By blending the substituted tetrazine compound (1) in the rubber composition containing carbon black, the dispersibility of carbon black can be significantly improved, and the low rolling resistance of the rubber composition can be significantly improved.

A vulcanizing agent is added to the rubber composition of the present invention, if necessary. Examples of the vulcanizing agent include sulfur and peroxide compounds. The blending amount of the vulcanizing agent is preferably 0.1 to 5 parts by mass, and more preferably 0.3 to 3 parts by mass with respect to 100 parts by mass of the rubber component.

When the rubber composition of the present invention contains a vulcanizing agent, it is preferable to further contain a vulcanization accelerator or a vulcanization delaying agent. Examples of vulcanization accelerators include N-cyclohexyl-2-benzothiazolyl sulphenamide, 1,3-diphenylguanidine, 2-mercaptobenzothiazole, tetramethylthiuram disulfide, trimethylthiourea, zinc dimethyldithiocarbamate, and isopropylxanthate. Examples include zinc acid acid. Examples of the vulcanization retarder include N-cyclohexylthiophthalimide and the like. The blending amount of the vulcanization accelerator or the vulcanization retarder can be appropriately adjusted within a range that does not impair the effects of the present invention.

Other Blending Agents In addition to the above fillers and vulcanizing agents, the rubber compositions of the present invention include blending agents commonly used in the rubber industry, such as antiaging agents, antioxidants, softeners, and waxes. , Resin, foaming agent, oil, stearic acid, zinc oxide (ZnO) and the like may be further blended. These compounding agents can be appropriately selected and compounded within a range that does not impair the object of the present invention. Commercially available products can be preferably used as these compounding agents.

Further, in a rubber composition containing a filler such as wet silica, a silane cup is used for the purpose of enhancing the reinforcing property of the rubber composition by the wet silica, or for the purpose of enhancing the rolling resistance and wear resistance of the rubber composition. A ring agent may be blended.

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

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

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

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

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

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

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

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

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

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

The blending amount of the silane coupling agent of the rubber composition of the present invention is preferably 0.1 to 20 parts by mass, and particularly preferably 3 to 15 parts by mass with respect to 100 parts by mass of the filler. If it is 0.1 part by mass or more, the effect of rolling resistance of the rubber composition can be more preferably exhibited, and if it is 20 parts by mass or less, the cost of the rubber composition is reduced and the economic efficiency is improved. Because it does.

When wet silica is included in the rubber composition, a silica processing aid is used to help disperse and / or shield the silica particles, suppress aggregation, reduce viscosity, and increase scorch time. Is preferable. In general, silica processing aids do not interact substantially with rubber molecules. As a silica processing aid, a monofunctional compound that chemically reacts with the surface silanol groups on the silica particles but does not react with the elastomer, and the silanol groups are physically shielded to suppress the rearrangement or aggregation of the silica particles. Shielding agents and the like. These silica processing aids can be used in place of all or part of the bifunctional silica coupling agent. In addition, the silica processing aid can improve the processability of the silica-filled rubber composition by lowering the compounding viscosity, increasing the scorch time, and reducing the reassortment of silica.

These processing aids can be used alone or in admixture of two or more.

The blending amount of the processing aid is usually 1 to 10 parts by mass, preferably 2 to 6 parts by mass, and more preferably 2 to 5 parts by mass with respect to 100 parts by mass of the rubber component.

Uses of rubber composition The use of the rubber composition of the present invention is not particularly limited, and examples thereof include tires, anti-vibration rubbers, seismic isolation rubbers, conveyor belts, and rubber portions thereof. Of these, a preferred application is a tire.

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 is, for example, a step (I) of kneading a rubber component, a substituted tetrazine compound (1), and a raw material component including a filler, a mixture obtained in the step (I), and addition. The step (II) of kneading the vulcanizing agent is included.

Step (I)
The step (I) is a step of kneading the rubber component, the substituted tetrazine compound (1), and the raw material component including the filler, and means that it is a step before blending the vulcanizing agent.

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

Examples of the kneading method in the step (I) include a method of kneading a composition containing a rubber component, a substituted tetrazine compound (1), and a filler such as wet silica. In this kneading method, the entire amount of each component may be kneaded at one time, or each component may be divided and kneaded according to the purpose such as viscosity adjustment. Further, the rubber component and the filler are kneaded and then the substituted tetrazine compound (1) is added and kneaded, or the rubber component and the substituted tetrazine compound (1) are kneaded and then the filler is added and kneaded. You may. Step (I) may be repeatedly kneaded a plurality of times.

The temperature at which the rubber composition is mixed in the step (I) is not particularly limited, and for example, the temperature of the rubber composition is preferably 120 to 190 ° C, more preferably 130 to 175 ° C. , 140-170 ° C. is more preferable.

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

In the step (I), the substituted tetrazine compound (1) is blended in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of the rubber component. The amount of the substituted tetrazine compound (1) to be blended is preferably 0.25 to 5 parts by mass, more preferably 0.5 to 2 parts by mass with respect to 100 parts by mass of the rubber component.

In step (I), when wet silica having a BET specific surface area in the range of 50 to 240 m ² / g is blended as a filler, the blending amount is usually 25 to 130 mass with respect to 100 parts by mass of the rubber component. It is a part, preferably 30 to 110 parts by mass, and more preferably 40 to 100 parts by mass.

In the step (I), when the inorganic filler is blended as the filler, the blending amount is usually 20 to 150 parts by mass, preferably 30 to 120 parts by mass with respect to 100 parts by mass of the rubber component. , More preferably 40 to 100 parts by mass.

When carbon black is blended as the filler in the step (I), the blending amount is usually 2 to 150 parts by mass, preferably 4 to 120 parts by mass with respect to 100 parts by mass of the rubber component. More preferably, it is 6 to 100 parts by mass.

In the step (I), the inorganic filler and / or carbon black is a total amount of both components, for example, 30 to 150 parts by mass with respect to 100 parts by mass of the rubber component. It may be adjusted appropriately within the range of the amount.

Further, as another kneading method in the step (I), a step (I-1) of kneading the rubber component and the substituted tetrazine compound (1), and a mixture (modified rubber) obtained in the step (I-1) are used. And a two-step kneading method including a step (I-2) of kneading the filler.

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

The kneading temperature is not particularly limited. For example, in the case of the above kneading method, the temperature of the rubber composition is preferably 80 to 190 ° C, more preferably 90 to 160 ° C, and 100 to 150. It is more preferably ° C. In the case of the liquid mixing method, the temperature of the liquid rubber composition is preferably 80 to 170 ° C., more preferably 90 to 160 ° C., and even more preferably 100 to 150 ° C.

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

In the step (I-1), the blending amount of the substituted tetrazine compound (1) is usually 0.1 to 10 parts by mass, preferably 0.25 to 5 parts by mass, and 0, based on 100 parts by mass of the rubber component. .5-2 parts by mass is more preferable.

By the step (I-1) of kneading the rubber component and the substituted tetrazine compound (1), the double bond of the diene rubber in the rubber component and the substituted tetrazine compound (1) react with each other to form the diene rubber. The main chain forms a modified rubber modified with a substituted pyridazine group.

In the step (I-2), the temperature at which the mixture (modified rubber) obtained in the step (I-1) and the filler are mixed is not particularly limited, and for example, the temperature of the mixture is 120 to 190. The temperature is preferably 130 to 175 ° C, more preferably 140 to 170 ° C.

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

In the step (I-2), when wet silica having a BET specific surface area in the range of 50 to 240 m ² / g is blended as the filler, the blending amount is the mixture obtained in the step (I-1) (I-1). The amount is 25 to 130 parts by mass, preferably 30 to 100 parts by mass, and more preferably 40 to 90 parts by mass with respect to 100 parts by mass of the modified rubber).

When an inorganic filler is blended as the filler in the step (I-2), the blending amount is usually 20 to 20 to 100 parts by mass of the mixture (modified rubber) obtained in the step (I-1). It is 150 parts by mass, preferably 30 to 120 parts by mass, and more preferably 40 to 90 parts by mass.

When carbon black is blended as a filler in the step (I-2), the blending amount is usually 2 to 150 with respect to 100 parts by mass of the mixture (modified rubber) obtained in the step (I-1). It is by mass, preferably 4 to 120 parts by mass, and more preferably 6 to 100 parts by mass.

In the step (I-2), the inorganic filler and / or carbon black is the total amount of both components, for example, with respect to 100 parts by mass of the mixture (modified rubber) obtained in the step (I-1). , Usually, it may be appropriately adjusted within the range of the above-mentioned blending amount of each component so as to be 30 to 150 parts by mass.

In step (I), the double bond portion of the rubber component (diene-based rubber) reacts with the substituted tetrazine compound (1) to form a modified rubber, and a mixture in which the filler is preferably dispersed can be obtained. ..

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

In step (II), a vulcanization accelerator or a vulcanization delaying agent can be further added, if necessary.

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

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

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

In the method for producing a rubber composition of the present invention, various compounding agents such as stearic acid, zinc oxide, and an antiaging agent, which are usually blended in the rubber composition, are used in step (I) or step (II), if necessary. Can be added in.

A rubber composition containing a modified rubber, a filler and a vulcanizing agent obtained by treating the diene-based rubber in the rubber component with the substituted tetrazine compound (1) by the above steps (I) and (II). Can be manufactured.

The rubber composition of the present invention includes a rubber component, a substituted tetrazine compound (1), a composition containing a filler and a vulcanizing agent, and a diene rubber in the rubber component and a substituted tetrazine compound (1). Both modified rubbers, fillers and rubber compositions containing vulcanizers obtained by the treatment are included.

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

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

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

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

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

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

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

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

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

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

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

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

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

Further, as the gas to be filled in the tire, normal or air with adjusted oxygen partial pressure; an inert gas such as nitrogen, argon or helium can be used.

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

Production Example 1: Production of 3,6-bis (3-pyridyl) -1,2,4,5-tetrazine (compound (1a)) In a 200 mL four-necked flask, 24 g (0.23 mol) of 3-cyanopyridine. , 15 g (1.3 eq) of hydrated 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 this mixture, a reflux tube was attached, and the mixture was heated and stirred overnight at an outside temperature of 70 ° C. The reaction was ice-cooled, the crystals were filtered and washed with a small amount of cold methanol. The crude crystals were dried under reduced pressure to obtain 19 g of orange dihydrotetrazine crude crystals.

17.8 g of the obtained crude crystals were dissolved in 178 g (40 equivalents) of acetic acid, and sulfur was removed by filtration. A dihydrotetrazine acetic acid solution and 178 mL of distilled water were added to a 1 L four-necked eggplant flask, and 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 the mixture was stirred overnight at room temperature. The precipitated crystals were filtered, and the crystals were neutralized with 10% layered water to obtain crude crystals. The crude crystals were purified on a silica gel column (ethyl acetate) to obtain 8.4 g (purple red, acicular crystals) of the title tetrazine compound (1a).
Melting point: 200 ° C,
^{1 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 4 and Comparative Examples 1 to 4
Each component shown in step (I) of Table 1 below was mixed at that ratio (part by mass), and kneaded with a Banbury mixer for 5 minutes while adjusting the rotation speed so that the maximum temperature of the mixture was 160 ° C. After curing until the temperature of the mixture is 80 ° C. or lower, each component shown in step (II) in Table 1 is added at that ratio (part by mass), and the maximum temperature of the mixture is adjusted to 110 ° C. or lower. While kneading, each rubber composition was produced. The number of substituted pyridazine groups in one molecule of the modified rubber of each rubber composition, tanδ measured at 0 ° C. and 1% strain, tanδ measured at 60 ° C. and 5% strain, and 25 ° C. and 5%. The storage elastic modulus (G') measured by strain is shown in Table 1.

Rolling resistance test Each tire (test tire) produced by using the rubber compositions obtained in Examples 1 to 4 and Comparative Examples 1 to 4 as a tire cap tread is subjected to a force method in accordance with JIS K d4234. The rolling resistance value was measured by a drum test, and the rolling resistance index was calculated by the following formula. The tire produced by using the rubber composition obtained in Comparative Example 2 was used as a control tire. The results are shown in Table 1.

Rolling resistance index = {(Rolling resistance value of control tire) / (Rolling resistance value of test tire)} x 100

WET Braking Test The braking distance of each test tire was measured by the actual vehicle method of ISO23671, and the WET braking index was calculated by the following formula. The tire produced by using the rubber composition obtained in Comparative Example 2 was used as a control tire. The results are shown in Table 1. The larger the index value, the better the performance on a wet road surface.

WET braking index = {(braking distance of control tire) / (braking distance of test tire)} x 100

Steering stability test For each test tire, the steering stability characteristics were evaluated on a test course on a dry road surface based on the feeling of the test driver. The tire produced by using the rubber composition obtained in Comparative Example 2 was used as a control tire, and the dry performance of the control tire was set to 100 and displayed as an index in Table 1.

The larger the index value, the better the handling characteristics and the better the steering stability.

[Explanation of symbols in the table]
The raw materials used in Table 1 are shown below.
* 1: Made by Asahi Kasei Corporation, product name "Toughden 2000R"
* 2: Product name "RSS # 3" manufactured by Chuka Kokusai Co., Ltd.
* 3: Product name "Nipsil (brand AQ)" manufactured by Toso Silica Co., Ltd.
* 4: Made by Evonik Industries AG, product name "Si75"
* 5: Product name "Seast 3" manufactured by Tokai Carbon Co., Ltd.
* 6: Yasuhara Chemical Co., Ltd., trade name "YS Polystar UH115" (softening point 115 ° C)
* 7: Product name "Antage 6C" manufactured by Kawaguchi Chemical Industry Co., Ltd.
* 8: Zinc oxide brand "1 type" manufactured by Sakai Chemical Industry Co., Ltd.
* 9: Made by Sichuan Tianyu Grease Chemical Co., Ltd. * 10: Made by Stratktor, trade name "HT254"
* 11: Product name "SNH220" manufactured by Sankyo Yuka Kogyo Co., Ltd.
* 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: Manufactured by Hosoi Chemical Industry Co., Ltd., product name "HK200-5"
* 16: Product name "Noxeller D" manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
* 17: Product name "Noxeller CZ-G" manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.

Since the rubber composition of the present invention has low rolling resistance while maintaining the braking performance and steering stability of the tire, the tread portion (tire tread) of a pneumatic tire of various automobiles can be used by using the rubber composition. Can be manufactured.

Claims (8)

A rubber composition containing a rubber component and a filler.
In 100 parts by mass of the rubber component, the main chain of the diene rubber is modified with a pyridazine group substituted with a pyridyl group which may have a substituent .
30 to 100 parts by mass of a modified rubber containing an average of 2 or more of the substituted pyridazine groups in one molecule of a diene rubber is contained.
Contains 35 to 150 parts by mass of filler with respect to 100 parts by mass of rubber component.
The loss tangent (tan δ) of the rubber composition measured at 0 ° C. and 1% strain is 0.25 to 1.3, and the tan δ measured at 60 ° C. and 5% strain is 0.05 to 0.35. A rubber composition having a storage elastic modulus (G') of 0.2 to 7 MPa as measured at 25 ° C. and 5% strain. The substituents are a halogen atom, an amino group, an aminoalkyl group, an alkoxycarbonyl group, an acyl group, an acyloxy group, an amide group, a carboxyl group, a carboxyalkyl group, a formyl group, a nitrile group, a nitro group, an alkyl group and a hydroxyalkyl group. The rubber composition according to claim 1, which is at least one selected from the group consisting of a hydroxyl group, an alkoxy group, an aryl group, an aryloxy group, a heterocyclic group, a thiol group, an alkylthio group, and an arylthio group. The rubber composition according to claim 1 or 2, wherein the substituted pyridazine group is formed by the reaction of the substituted tetrazazine compound with the double bond of the diene rubber contained in the rubber component. The rubber composition according to claim 3, wherein the reaction between the substituted tetrazine compound and the diene rubber occurs in a rubber kneading mixer in the range of 80 to 180 ° C. The rubber composition according to any one of claims 1 to 4, which contains 25 to 130 parts by mass of wet silica having a BET specific surface area in the range of 50 to 240 m ² / g with respect to 100 parts by mass of the rubber component. The rubber composition according to any one of claims 1 to 5, which is used for a tread portion. A tire tread produced by using the rubber composition according to any one of claims 1 to 5. A pneumatic tire using the tire tread according to claim 7.