JP7441114B2 - Low heat build-up agent for rubber compositions, tires, and rubber - Google Patents

Description

The present invention relates to a rubber composition, a tire, and a low heat generation agent for rubber.

When manufacturing tires, it is known that by blending carbon black, tires with excellent wear resistance can be obtained.

Furthermore, natural rubber is generally used as the rubber used for tires. Furthermore, synthetic diene rubber and silica are sometimes blended to improve the tire's rolling resistance, wet grip performance, and handling stability on snow.

It is said that the rolling resistance of tires has an effect on the fuel efficiency of automobiles, and it is known that it is effective to use rubber compositions with low heat generation for tire materials with low rolling resistance.

Hitherto, a hydrazone compound disclosed in Patent Document 1 has been proposed as a low heat build-up imparting agent added to a rubber composition for tires.

However, there is a strong demand for rubber compositions that have even better low heat generation properties. Furthermore, tires used for trucks, buses, etc. are required to have resistance to high loads, and therefore, in addition to the above-mentioned excellent low heat generation property, a certain level of durability is also required.

However, since there is no clear correlation between low heat build-up and durability in a rubber composition, it is difficult to find a rubber composition that has both properties in a high-dimensional well-balanced manner.

JP 2017-7551 Publication

In view of the above-mentioned circumstances, an object of the present invention is to provide a rubber composition that has durability equivalent to that of conventional products and has even better low heat generation properties.

As a result of intensive research to achieve the above object, the present inventor has found that a rubber compound containing a specified tetrazine compound and a specified hydrazone compound in a certain ratio in addition to a specified rubber component, silica, and carbon black. It has been found that by employing the composition, it is possible to obtain a tire that has sufficient durability and excellent low heat generation properties. The present inventor has conducted further research based on this knowledge and has completed the present invention.

[式中、Ｘ_１及びＸ_２は、同一又は異なって、置換基を有していてもよい複素環基を示す。]

[式中、Ｒ_１及びＲ_２は、同一又は異なって、水素原子、Ｃ１～１８のアルキル基、シクロアルキル基又は芳香族基を示す。Ｒ_３は、Ｃ２～１８の多価の非環式脂肪族基、Ｃ５～２０の多価の環式脂肪族基、Ｃ６～１８の多価の芳香族基、又はＣ７～２４の多価のアルキル芳香族基を示す。Ａは水素原子、ヒドロキシ基、アミノ基、又はメルカプト基を示す。ｎは、１～３の整数を示す。]
項２．
前記天然ゴム及び前記合成ジエン系ゴムの合計１００質量％中における前記天然ゴムの含有量が１０～８０質量％である、項１に記載の組成物。
項３．
前記合成系ジエン系ゴムが、イソプレンゴム、スチレンブタジエンゴム及びブタジエンゴムからなる群より選択される少なくとも一種である、項１又は２に記載の組成物。
項４．
前記式（１）における複素環基はピリジル基である、項１～３の何れかに記載の組成物。
項５．
前記式（２）で表される化合物が、Ｎ'－(１－メチルエチリデン)サリチル酸ヒドラジド、Ｎ'－(１－メチルプロピリデン)サリチル酸ヒドラジド、Ｎ'－(１,３－ジメチルブチリデン)サリチル酸ヒドラジド、Ｎ'－(２－フリルメチレン)サリチル酸ヒドラジド、１－ヒドロキシ－Ｎ'－(１－メチルエチリデン)－２－ナフトエ酸ヒドラジド、１－ヒドロキシ－Ｎ'－(１－メチルプロピリデン)－２－ナフトエ酸ヒドラジド、１－ヒドロキシ－Ｎ'－(１,３－ジメチルブチリデン)－２－ナフトエ酸ヒドラジド、１－ヒドロキシ－Ｎ'－(２－フリルメチレン)－２－ナフトエ酸ヒドラジド、３－ヒドロキシ－Ｎ'－(１－メチルエチリデン)－２－ナフトエ酸ヒドラジド、３－ヒドロキシ－Ｎ'－(１－メチルプロピリデン)－２－ナフトエ酸ヒドラジド、３－ヒドロキシ－Ｎ'－(１,３－ジメチルブチリデン)－２－ナフトエ酸ヒドラジド及びヒドロキシ－Ｎ'－(２－フリルメチレン)－２－ナフトエ酸ヒドラジドからなる群から選ばれる少なくとも１種である、項１～４の何れかに記載の組成物。
項６．
タイヤのトレッド部に使用される、項１～５の何れかに記載の組成物。
項７．
項１～６の何れかに記載の組成物を用いて製造されたタイヤ。
項８．
重荷重用である、項７に記載のタイヤ。
項９．
下記式（１）で表される化合物又はその塩、並びに下記式（２）で表される化合物を含む、ゴム用低発熱化剤。

[式中、Ｘ_１及びＸ_２は、同一又は異なって、置換基を有していてもよい複素環基を示す。]

[式中、Ｒ_１及びＲ_２は、同一又は異なって、水素原子、Ｃ１～１８のアルキル基、シクロアルキル基又は芳香族基を示す。Ｒ_３は、Ｃ２～１８の多価の非環式脂肪族基、Ｃ５～２０の多価の環式脂肪族基、Ｃ６～１８の多価の芳香族基、又はＣ７～２４の多価のアルキル芳香族基を示す。Ａは水素原子、ヒドロキシ基、アミノ基、又はメルカプト基を示す。ｎは、１～３の整数を示す。] That is, the present invention provides the following rubber composition, tire, and low heat generation agent for rubber.
Item 1.
Contains a rubber component including natural rubber and synthetic diene rubber, silica, carbon black, a compound represented by the following formula (1) or a salt thereof, and a compound represented by the following formula (2),
The blending amount of each component is based on a total of 100 parts by mass of the natural rubber and the synthetic diene rubber,
the silica is 15 to 120 parts by mass,
5 to 80 parts by mass of the carbon black,
0.05 to 10 parts by mass of the compound represented by formula (1) or a salt thereof,
A rubber composition containing 0.05 to 10 parts by mass of the compound represented by formula (2) or a salt thereof.

[In the formula, X ₁ and X ₂ are the same or different and represent a heterocyclic group which may have a substituent. ]

[In the formula, R ₁ and R ₂ are the same or different and represent a hydrogen atom, a C1-18 alkyl group, a cycloalkyl group, or an aromatic group. R ₃ is a C2-18 polyvalent acyclic aliphatic group, a C5-20 polyvalent cycloaliphatic group, a C6-18 polyvalent aromatic group, or a C7-24 polyvalent aromatic group. Indicates an alkyl aromatic group. A represents a hydrogen atom, a hydroxy group, an amino group, or a mercapto group. n represents an integer from 1 to 3. ]
Item 2.
Item 2. The composition according to item 1, wherein the content of the natural rubber is 10 to 80% by mass in a total of 100% by mass of the natural rubber and the synthetic diene rubber.
Item 3.
Item 3. The composition according to Item 1 or 2, wherein the synthetic diene rubber is at least one selected from the group consisting of isoprene rubber, styrene-butadiene rubber, and butadiene rubber.
Item 4.
Item 4. The composition according to any one of items 1 to 3, wherein the heterocyclic group in formula (1) is a pyridyl group.
Item 5.
The compound represented by the formula (2) is N'-(1-methylethylidene)salicylic acid hydrazide, N'-(1-methylpropylidene)salicylic acid hydrazide, N'-(1,3-dimethylbutylidene)salicylic acid Hydrazide, N'-(2-furylmethylene)salicylic acid hydrazide, 1-hydroxy-N'-(1-methylethylidene)-2-naphthoic acid hydrazide, 1-hydroxy-N'-(1-methylpropylidene)-2 -Naphthoic acid hydrazide, 1-hydroxy-N'-(1,3-dimethylbutylidene)-2-naphthoic acid hydrazide, 1-hydroxy-N'-(2-furylmethylene)-2-naphthoic acid hydrazide, 3- Hydroxy-N'-(1-methylethylidene)-2-naphthoic acid hydrazide, 3-hydroxy-N'-(1-methylpropylidene)-2-naphthoic acid hydrazide, 3-hydroxy-N'-(1,3 -dimethylbutylidene)-2-naphthoic acid hydrazide and hydroxy-N'-(2-furylmethylene)-2-naphthoic acid hydrazide, according to any one of items 1 to 4, which is at least one selected from the group consisting of -2-naphthoic acid hydrazide. Composition of.
Item 6.
Item 6. The composition according to any one of Items 1 to 5, which is used for a tread portion of a tire.
Section 7.
Item 7. A tire manufactured using the composition according to any one of Items 1 to 6.
Section 8.
The tire according to item 7, which is for heavy loads.
Item 9.
A low heat build-up agent for rubber, comprising a compound represented by the following formula (1) or a salt thereof, and a compound represented by the following formula (2).

[In the formula, X ₁ and X ₂ are the same or different and represent a heterocyclic group which may have a substituent. ]

[In the formula, R ₁ and R ₂ are the same or different and represent a hydrogen atom, a C1-18 alkyl group, a cycloalkyl group, or an aromatic group. R ₃ is a C2-18 polyvalent acyclic aliphatic group, a C5-20 polyvalent cycloaliphatic group, a C6-18 polyvalent aromatic group, or a C7-24 polyvalent aromatic group. Indicates an alkyl aromatic group. A represents a hydrogen atom, a hydroxy group, an amino group, or a mercapto group. n represents an integer from 1 to 3. ]

The rubber composition of the present invention has durability equivalent to that of conventional products, but has even better low heat generation properties.

(1. Rubber composition)
The rubber composition of the present invention contains a rubber component, silica, carbon black, a compound represented by formula (1) described below or a salt thereof, and a compound represented by formula (2) described below. The rubber composition of the present invention has durability comparable to that of conventional products, but has even better low heat generation properties, and can be suitably used as a rubber composition for tires. Among these, it can be suitably used as a rubber composition for tires of trucks, buses, aircraft, industrial vehicles, etc. that are subject to high loads.

(1.1. Rubber component)
Rubber components include natural rubber and synthetic diene rubber. The rubber component may include rubber components other than natural rubber and synthetic diene rubber. In 100% by mass of the rubber component, the total content of natural rubber and synthetic diene rubber is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. It is also preferable that the rubber component consists only of natural rubber and synthetic diene rubber.

Examples of natural rubber include natural rubber latex, technically graded rubber (TSR), smoked sheet (RSS), gutta-percha, natural rubber derived from mori, natural rubber derived from guayule, and natural rubber derived from Russian dandelion. Modified natural rubbers such as epoxidized natural rubber, methacrylic acid-modified natural rubber, and styrene-modified natural rubber are also defined as being included in natural rubber.

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 rubber. Examples include polymer rubber (EPDM), styrene-isoprene-styrene triblock copolymer (SIS), styrene-butadiene-styrene triblock copolymer (SBS), and modified synthetic diene rubbers thereof. Modified synthetic diene rubbers include diene rubbers produced by modification methods such as main chain modification, one-terminal modification, and both-terminal modification. Here, the modified functional groups of the modified synthetic diene rubber include various functional groups such as epoxy groups, amino groups, alkoxysilyl groups, and hydroxyl groups, and one or more of these functional groups are present in the modified synthetic diene rubber. May be included in rubber.

Among the synthetic diene rubbers described above, it is preferable to use at least one selected from the group consisting of isoprene rubber, styrene-butadiene rubber, and butadiene rubber in order to achieve both wear resistance and processability.

The method for producing the synthetic diene rubber is not particularly limited, and examples include emulsion polymerization, solution polymerization, radical polymerization, anionic polymerization, and cationic polymerization. Furthermore, there are no particular limitations on the glass transition point of the synthetic diene rubber.

Further, there is no particular restriction on the cis/trans/vinyl ratio of the double bond in natural rubber and synthetic diene rubber, and any ratio can be suitably used. Further, the number average molecular weight and molecular weight distribution of the synthetic diene rubber are not particularly limited, but preferably a number average molecular weight of 500 to 3,000,000 and a molecular weight distribution of 1.5 to 15.

The rubber components can be used alone or in a mixture (blend) of two or more. Among these, preferable rubber components are natural rubber, IR, SBR, BR, or a mixture of two or more selected from these, and more preferably natural rubber, SBR, BR, or a mixture of two or more selected from these. .

Regarding the blending amount of natural rubber and synthetic diene rubber, it is preferable that natural rubber is 20 to 80% by mass, and preferably 25 to 60% by mass, in 100% by mass of the total of natural rubber and synthetic diene rubber. More preferred. By adopting such a configuration, it is possible to achieve both wear resistance and wet braking performance.

Rubber components other than natural rubber and synthetic diene rubber may include polysulfide rubber, silicone rubber, fluororubber, and urethane rubber, and are not particularly limited.

(1.2. Silica)
Any commercially available silica can be used. Among them, it is preferable to use wet silica, dry silica, or colloidal silica, and it is more preferable to use wet silica. The surface of these silicas may be organically treated in order to improve the affinity with the rubber component.

There is no particular limitation on the BET specific surface area of silica, and for example, a range of 40 to 350 m ² /g can be mentioned. Silica having a BET specific surface area within this range has the advantage of being able to achieve both rubber reinforcing properties and dispersibility into the rubber component. The BET specific surface area is measured in accordance with ISO5794/1.

From this point of view, preferred silica is silica with a BET specific surface area of 80 to 300 m ² /g, more preferably silica with a BET specific surface area of 100 to 270 m ² /g, particularly preferably: Silica has a BET specific surface area of 110 to 270 m ² /g.

Commercial products of such silica include those available from Quechen Silicon Chemical Co.; , Ltd. Product names "HD165MP" (BET specific surface area = 165 m ² /g), "HD115MP" (BET specific surface area = 115 m ² /g), "HD200MP" (BET specific surface area = 200 m ² /g), "HD250MP" ( BET specific surface area = 250 m ² /g), product name "Nip Seal AQ" manufactured by Tosoh Silica Co., Ltd. (BET specific surface area = 205 m ² /g), "Nip Seal KQ" (BET specific surface area = 240 m ² /g), Degussa Examples include "Ultrasil VN3" (BET specific surface area = 175 m ² /g) manufactured by Co., Ltd. under the trade name of "Ultrasil VN3".

The amount of silica blended is 15 to 120 parts by mass, preferably 20 to 100 parts by mass, and 30 to 70 parts by mass, based on the total of 100 parts by mass of the above-mentioned natural rubber and synthetic diene rubber. is more preferable. If the amount of silica blended is less than 15 parts by mass with respect to a total of 100 parts by mass of natural rubber and synthetic diene rubber, rolling resistance performance will deteriorate. On the other hand, if the amount of silica exceeds 120 parts by mass, the processability of the rubber composition will deteriorate.

(1.3. Carbon black)
The carbon black to be used is not particularly limited, and examples thereof include commercially available carbon black, Carbon-Silica dual phase filler, and the like. By incorporating carbon black into the rubber component, it is possible to obtain the effect of lowering the electrical resistance of the rubber, suppressing charging, and further improving the strength of the rubber.

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

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

Further, the nitrogen adsorption specific surface area (N2SA, measured according to JISK6217-2:2001) of carbon black is preferably 30 to 200 m ² /g, more preferably 40 to 180 m ² /g. , more preferably 50 to 160 m ² /g.

The blending amount of carbon black is 5 to 80 parts by mass, preferably 7 to 50 parts by mass, and 10 to 30 parts by mass, based on the total of 100 parts by mass of the above-mentioned natural rubber and synthetic diene rubber. It is more preferable. If the amount of carbon black is less than 5 parts by mass based on the total of 100 parts by mass of natural rubber and synthetic diene rubber, poor coloring will result. On the other hand, if the amount of carbon black exceeds 80 parts by mass, processability will be poor.

(1.4. Compound represented by formula (1) or its salt)
The composition of the present invention contains a compound represented by the following formula (1) or a salt thereof (hereinafter also simply referred to as a "tetrazine compound").

[式中、Ｘ_１及びＸ_２は、同一又は異なって、置換基を有していてもよい複素環基を示す。]

[In the formula, X ₁ and X ₂ are the same or different and represent a heterocyclic group which may have a substituent. ]

The heterocyclic group in the tetrazine compound is not particularly limited, and includes, for example, 2-pyridyl, 3-pyridyl, 4-pyridyl, 2-pyrazinyl, 2-pyrimidyl, 4-pyrimidyl, 5-pyrimidyl, 3-pyridazyl, 4-pyridyl, Pyridazyl, 4-(1,2,3-triazyl), 5-(1,2,3-triazyl), 2-(1,3,5-triazyl), 3-(1,2,4-triazyl), 5-(1,2,4-triazyl), 6-(1,2,4-triazyl), 2-quinolyl, 3-quinolyl, 4-quinolyl, 5-quinolyl, 6-quinolyl, 7-quinolyl, 8- Quinolyl, 1-isoquinolyl, 3-isoquinolyl, 4-isoquinolyl, 5-isoquinolyl, 6-isoquinolyl, 7-isoquinolyl, 8-isoquinolyl, 2-quinoxalyl, 3-quinoxalyl, 5-quinoxalyl, 6-quinoxalyl, 7-quinoxalyl, 8-quinoxalyl, 3-cinnolyl, 4-cinnolyl, 5-cinnolyl, 6-cinnolyl, 7-cinnolyl, 8-cinnolyl, 2-quinazolyl, 4-quinazolyl, 5-quinazolyl, 6-quinazolyl, 7-quinazolyl, 8- Quinazolyl, 1-phthaladyl, 4-phthaladyl, 5-phthaladyl, 6-phthaladyl, 7-phthaladyl, 8-phthaladyl, 1-tetrahydroquinolyl, 2-tetrahydroquinolyl, 3-tetrahydroquinolyl, 4-tetrahydroquinolyl, 5-tetrahydroquinolyl, 6-tetrahydroquinolyl, 7-tetrahydroquinolyl, 8-tetrahydroquinolyl, 1-pyrrolyl, 2-pyrrolyl, 3-pyrrolyl, 2-furyl, 3-furyl, 2-thienyl, 3- thienyl, 1-imidazolyl, 2-imidazolyl, 4-imidazolyl, 5-imidazolyl, 1-pyrazolyl, 3-pyrazolyl, 4-pyrazolyl, 5-pyrazolyl, 2-oxazolyl, 4-oxazolyl, 5-oxazolyl, 2-thiazolyl, 4-thiazolyl, 5-thiazolyl, 3-isoxazolyl, 4-isoxazolyl, 5-isoxazolyl, 3-isothiazolyl, 4-isothiazolyl, 5-isothiazolyl, 4-(1,2,3-thiadiazolyl), 5-(1,2 , 3-thiadiazolyl), 3-(1,2,5-thiadiazole), 2-(1,3,4-thiadiazole), 4-(1,2,3-oxadiazolyl), 5-(1,2,3 -oxadiazolyl), 3-(1,2,4-oxadiazolyl), 5-(1,2,4-oxadiazolyl), 3-(1,2,5-oxadiazolyl), 2-(1,3,4-oxadiazolyl) ), 1-(1,2,3-triazolyl), 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, 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, 4-benzothiazolyl, 5- Benzothiazolyl, 6-benzothiazolyl, 7-benzothiazolyl, 1-indazolyl, 3-indazolyl, 4-indazolyl, 5-indazolyl, 6-indazolyl, 7-indazolyl, 2-morpholyl, 3-morpholyl, 4-morpholyl, 1-piperazyl, 2-piperazyl, 1-piperidyl, 2-piperidyl, 3-piperidyl, 4-piperidyl, 2-tetrahydropyranyl, 3-tetrahydropyranyl, 4-tetrahydropyranyl, 2-tetrahydrothiopyranyl, 3-tetrahydrothiopyranyl and 4-tetrahydrothiopyranyl, 1-pyrrolidyl, 2-pyrrolidyl, 3-pyrrolidyl, 2-tetrahydrofuranyl, 3-tetrahydrofuranyl, 2-tetrahydrothienyl, 3-tetrahydrothienyl, and the like. Among these, preferred heterocyclic groups are pyridyl, furanyl, thienyl, pyrimidyl, or pyrazyl, and pyridyl is more preferred.

In addition, there are no particular limitations on the substituent optionally added to X _{1 or} Examples include carboxyl group, carboxyalkyl group, formyl group, nitrile group, nitro group, alkyl group, hydroxyalkyl group, hydroxyl group, alkoxy group, aryl group, aryloxy group, heterocyclic group, thiol group, alkylthio group, arylthio group, etc. It will be done. The substituent may preferably have 1 to 5, more preferably 1 to 3 substituents.

The "salt" of the compound represented by 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; magnesium salt and calcium salt. Alkaline earth metal salts such as salts; quaternary ammonium salts such as dimethylammonium and triethylammonium; and the like.

Among these tetrazine compounds, preferred compounds are those in which X ₁ and X ₂ are the same or different and are an alkyl group that may have a substituent, an aralkyl group that may have a substituent, or a aralkyl group that may have a substituent. A compound that is an optionally substituted aryl group or a heterocyclic group that optionally has a substituent.

A more preferred tetrazine compound is one in which X ₁ and X ₂ are the same or different and have an optionally substituted aralkyl group, an optionally substituted aryl group, or a substituent. This compound is a good heterocyclic group.

In a more preferred tetrazine compound, X ₁ and X ₂ are the same or different, and are a benzyl group that may have a substituent, a phenyl group that may have a substituent, or a phenyl group that may have a substituent. 2-pyridyl group that may have a substituent, 3-pyridyl group that may have a substituent, 4-pyridyl group that may have a substituent, 2-furanyl group that may have a substituent, substituent a thienyl group which may have a substituent, a 1-pyrazolyl group which may have a substituent, a 2-pyrimidyl group which may have a substituent, or a 2-pyrimidyl group which may have a substituent. A compound that is a pyrazyl group, and among these, a 2-pyridyl group that may have a substituent, a 3-pyridyl group that may have a substituent, or a 3-pyridyl group that may have a substituent. Particularly preferred are compounds which are 2-furanyl groups.

Specifically, as the tetrazine compound, for example,
1,2,4,5-tetrazine,
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-diphenyl-1,2,4,5-tetrazine,
3,6-dibenzyl-1,2,4,5-tetrazine,
3,6-bis(2-furanyl)-1,2,4,5-tetrazine,
3-methyl-6-(3-pyridyl)-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(4-hydroxyphenyl)-1,2,4,5-tetrazine,
3,6-bis(3-hydroxyphenyl)-1,2,4,5-tetrazine,
3,6-bis(2-pyrimidinyl)-1,2,4,5-tetrazine,
Examples include 3,6-bis(2-pyrazyl)-1,2,4,5-tetrazine.
Among these, preferred tetrazine compounds are 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine, 3,6-bis(3-pyridyl)-1,2,4,5-tetrazine, 3 , 6-bis(2-furanyl)-1,2,4,5-tetrazine, 3-methyl-6-(3-pyridyl)-1,2,4,5-tetrazine, and 3-methyl-6-( 2-pyridyl)-1,2,4,5-tetrazine, and the more preferred tetrazine compound is 3-pyridyl)-1,2,4,5-tetrazine.

The above-mentioned tetrazine compounds may be used alone or in combination of two or more.

The amount of the tetrazine compound used is 0.05 to 10 parts by weight, preferably 0.10 to 7 parts by weight, and preferably 0.15 to 7 parts by weight, based on the total of 100 parts by weight of the above natural rubber and synthetic diene rubber. More preferably, the amount is 5 parts by mass. If the amount of the tetrazine compound used is less than 0.05 parts by mass, rolling resistance performance will deteriorate. On the other hand, if the amount of the tetrazine compound used exceeds 10 parts by mass, processability will be poor.

(1.5. Compound represented by formula (2))
The composition of the present invention contains a compound represented by the following formula (2). In this specification, the compound is also simply referred to as a "hydrazide compound."

[式中、Ｒ_１及びＲ_２は、同一又は異なって、水素原子、Ｃ１～１８のアルキル基、シクロアルキル基又は芳香族基を示す。Ｒ_３は、Ｃ２～１８の多価の非環式脂肪族基、Ｃ５～２０の多価の環式脂肪族基、Ｃ６～１８の多価の芳香族基、又はＣ７～２４の多価のアルキル芳香族基を示す。Ａは水素原子、ヒドロキシ基、アミノ基、又はメルカプト基を示す。ｎは、１～３の整数を示す。]

[In the formula, R ₁ and R ₂ are the same or different and represent a hydrogen atom, a C1-18 alkyl group, a cycloalkyl group, or an aromatic group. R ₃ is a C2-18 polyvalent acyclic aliphatic group, a C5-20 polyvalent cycloaliphatic group, a C6-18 polyvalent aromatic group, or a C7-24 polyvalent aromatic group. Indicates an alkyl aromatic group. A represents a hydrogen atom, a hydroxy group, an amino group, or a mercapto group. n represents an integer from 1 to 3. ]

In formula (2), R ₁ and R ₂ are the same or different and are a hydrogen atom, a C1-18 alkyl group, a cycloalkyl group, or an aromatic group. Among them, R ₁ and R ₂ are preferably the same or different and are preferably C1-18 alkyl groups, and preferably C1-5 alkyl groups. The alkyl group may be linear or branched.

R ₃ is a C2-18 polyvalent acyclic aliphatic group, a C5-20 polyvalent cycloaliphatic group, a C6-18 polyvalent aromatic group, or a C7-24 polyvalent aromatic group. Indicates an alkyl aromatic group. R ₃ is an acyclic aliphatic group which may have a C2-18 substituent, a cycloaliphatic group which may have a C5-20 substituent, or a C6-18 substituent. It is preferably an aromatic group which may have one or an alkyl aromatic group which may have a C7 to C24 substituent. The substituent is not particularly limited, and includes, 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. group, alkyl group, hydroxyalkyl group, hydroxyl group, alkoxy group, aryl group, aryloxy group, heterocyclic group, thiol group, alkylthio group, arylthio group, and the like. The substituent may preferably have 1 to 5, more preferably 1 to 3 substituents.

Specific examples of hydrazide compounds include derivatives of 3-hydroxy-2-naphthoic acid hydrazide (HNH), N'-(1,3-dimethylbutylidene)salicylic acid hydrazide (BMS), and 4-hydroxybenzoic acid. Examples include derivatives of hydrazide, anthranilic acid hydrazide, and 1-hydroxy-2-naphthoic acid hydrazide. Among these, it is preferable to use naphthoic acid hydrazide or its derivatives.

In addition, N'-(1-methylethylidene) salicylic acid hydrazide, N'-(1-methylpropylidene) salicylic acid hydrazide, N'-(1,3-dimethylbutylidene) salicylic acid hydrazide, N'-(2- Furylmethylene) salicylic acid hydrazide, 1-hydroxy-N'-(1-methylethylidene)-2-naphthoic acid hydrazide, 1-hydroxy-N'-(1-methylpropylidene)-2-naphthoic acid hydrazide, 1-hydroxy -N'-(1,3-dimethylbutylidene)-2-naphthoic acid hydrazide, 1-hydroxy-N'-(2-furylmethylene)-2-naphthoic acid hydrazide, 3-hydroxy-N'-(1- methylethylidene)-2-naphthoic acid hydrazide, 3-hydroxy-N'-(1-methylpropylidene)-2-naphthoic acid hydrazide, 3-hydroxy-N'-(1,3-dimethylbutylidene)-2- Examples include naphthoic acid hydrazide and hydroxy-N'-(2-furylmethylene)-2-naphthoic acid hydrazide.

Examples of derivatives of 3-hydroxy-2-naphthoic acid hydrazide (HNH) include 3-hydroxy-2-naphthoic acid (1-methylethylidene) hydrazide and 3-hydroxy-2-naphthoic acid (1-methylpropylidene). hydrazide, 3-hydroxy-2-naphthoic acid hydrazide such as 3-hydroxy-2-naphthoic acid (1,3-dimethylpropylidene) hydrazide, 3-hydroxy-2-naphthoic acid (1-phenylethylidene) hydrazide, etc. It will be done.

Among these, derivatives of 3-hydroxy-2-naphthoic acid hydrazide (for example, the product name "HNH" manufactured by Otsuka Chemical Co., Ltd. corresponds to this compound) and N'-(1,3-dimethylbutyric acid) Derivatives of salicylic acid hydrazide (for example, the trade name "BMS" manufactured by Otsuka Chemical Co., Ltd. corresponds to this compound) are preferable in that they can keep Mooney viscosity low while maintaining low heat generation. In particular, 3-hydroxy-N'-(1,3-dimethylbutylidene)-2-naphthoic acid hydrazide, which is a derivative of 3-hydroxy-2-naphthoic acid hydrazide ("HNH"), has remarkable effects. Preferably, as a commercially available product, for example, the trade name "BMH" manufactured by Otsuka Chemical Co., Ltd. can be suitably used. In addition, in the rubber composition of the present invention, the above-mentioned hydrazide compounds may be used alone or in combination of two or more.

The amount of the hydrazide compound used is 0.05 to 10 parts by weight, preferably 0.10 to 7 parts by weight, and preferably 0.15 to 7 parts by weight, based on the total of 100 parts by weight of the natural rubber and synthetic diene rubber. More preferably, the amount is 5 parts by mass. If the amount of the hydrazide compound used is less than 0.05 parts by mass, rolling resistance performance will deteriorate. On the other hand, if the amount of the hydrazide compound used exceeds 10 parts by mass, processability will be poor.

The amount of the hydrazide compound to be used relative to the tetrazine compound is preferably 30 to 300 parts by mass, more preferably 50 to 200 parts by mass, and 75 to 125 parts by mass relative to 100 parts by mass of the tetrazine compound. It is more preferable to do so. By blending both compounds at the above composition ratio, excellent low heat generation properties can be obtained synergistically.

(1.6. Other compounded agents)
In addition to the above-mentioned components, the rubber composition of the present invention includes a coupling agent, an inorganic filler other than carbon black and silica, a vulcanizing agent, a vulcanization accelerator, a vulcanization accelerator, an anti-aging agent, and a softening agent. Compounding agents commonly used in the rubber industry, such as additives, plasticizers, scorch inhibitors, antiozonants, blowing agents, and vulcanization retarders, can be appropriately blended.

It is also preferable that the rubber composition of the present invention contains a coupling agent. By adding a coupling agent, the reinforcing properties of the rubber composition can be enhanced, and the tear strength and abrasion resistance of the rubber composition can be enhanced. More specifically, a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, or a zirconate coupling agent may be blended.

The silane coupling agent is not particularly limited, and commercially available products can be suitably used. Examples of such silane coupling agents include sulfide-based, polysulfide-based, thioester-based, thiol-based, olefin-based, epoxy-based, amino-based, and alkyl-based silane coupling agents.

Examples of sulfide-based silane coupling agents include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(3-methyldimethoxysilylpropyl)tetrasulfide, and bis(3-trimethoxysilylpropyl)tetrasulfide. 2-triethoxysilylethyl)tetrasulfide, bis(3-triethoxysilylpropyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(3-methyldimethoxysilylpropyl)disulfide, bis(2-triethoxysilyl) ethyl) disulfide, bis(3-triethoxysilylpropyl) trisulfide, bis(3-trimethoxysilylpropyl) trisulfide, bis(3-methyldimethoxysilylpropyl) trisulfide, bis(2-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. Among these, bis3-triethoxysilylpropyl) tetrasulfide is particularly preferred.

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

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

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

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

Examples of amino-based silane coupling agents include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyl Trimethoxysilane, 3-aminopropyltriethoxysilane, 3-ethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-(vinylbenzyl)- Examples include 2-aminoethyl-3-aminopropyltrimethoxysilane. Among these, 3-aminopropyltriethoxysilane is preferred.

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

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

The titanate coupling agent is not particularly limited, and commercially available products can be suitably used. Examples of such titanate coupling agents include alkoxide-based, chelate-based, and acylate-based titanate coupling agents.

Examples of the alkoxide-based titanate coupling agent include tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetraoctyl titanate, tetratert-butyl titanate, tetrastearyl titanate, and the like. Among these, tetraisopropyl titanate is preferred.

Examples of chelate-based titanate coupling agents include titanium acetylacetonate, titanium tetraacetylacetonate, titanium ethyl acetoacetate, titanium dodecylbenzenesulfonic acid compounds, titanium phosphate compounds, titanium octylene glycolate, and titanium ethyl acetoacetate. , titanium lactate ammonium salt, titanium lactate, titanium ethanolaminate, titanium octylene glycolate, titanium aminoethylaminoethanolate, and the like. Among these, titanium acetylacetonate is preferred.

Examples of the acylate-based titanate coupling agent include titanium isostearate.

The aluminate coupling agent is not particularly limited, and commercially available products can be suitably used. Examples of such aluminate coupling agents include 9-octadecenylacetoacetate aluminum diisopropylate, aluminum secondary butoxide, aluminum trisacetylacetonate, aluminum bisethylacetoacetate monoacetylacetonate, aluminum trisethylacetoacetate, etc. can be mentioned. Among these, 9-octadecenyl acetoacetate aluminum diisopropylate is preferred.

The zirconate coupling agent is not particularly limited, and commercially available products can be suitably used. Examples of such zirconate coupling agents include alkoxide-based, chelate-based, and acylate-based zirconate coupling agents.

Examples of the alkoxide-based zirconium coupling agent include normal propyl zirconate and normal butyl zirconate. Among these, normal butyl zirconate is preferred.

Examples of chelate-based zirconate coupling agents include zirconium tetraacetylacetonate, zirconium monoacetylacetonate, zirconium ethyl acetoacetate, and zirconium lactate ammonium salt. Among these, zirconium tetraacetylacetonate is preferred.

Examples of the acylate-based zirconate coupling agent include zirconium stearate and zirconium octylate. Among these, zirconium stearate is preferred.

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

The blending amount of the silane coupling agent in the rubber composition of the present invention is preferably 0.1 to 20 parts by weight, more preferably 3 to 15 parts by weight, based on 100 parts by weight of silica. When it is 0.1 parts by mass or more, the effect of improving the tear strength of the rubber composition can be more suitably expressed, and when it is 20 parts by mass or less, the cost of the rubber composition is reduced and economical efficiency is improved. Because it does.

Examples of inorganic fillers include calcium carbonate (CaCO ₃ ), alumina (Al ₂ O ₃ ), alumina hydrate (Al ₂ O ₃ .H ₂ O), aluminum hydroxide [Al(OH) ₃ ], and aluminum carbonate [ _Al2 ( _CO3 ) ₃ ], magnesium hydroxide [Mg(OH) ₂ ], magnesium oxide (MgO), magnesium carbonate ( _MgCO3 ), talc (3MgO・_4SiO2・_H2O ), attapulgite (5MgO・8SiO ₂・9H ₂ O), titanium white (TiO ₂ ), titanium black (TiO _2n-1 ), calcium oxide (CaO), calcium hydroxide [Ca(OH) ₂ ], aluminum magnesium oxide (MgO・Al ₂ O ₃ ) _, clay ( _{Al2O3.2SiO2 ) ,} kaolin ( _{Al2O3.2SiO2.2H2O ) ,} pyrophyllite ( _{Al2O3.4SiO2.H2O )} , _{bentonite ( Al2O 3.4SiO2.2H2O} ), aluminum silicate ( _Al2SiO5 , _{Al4.3SiO4.5H2O ,} etc.), magnesium silicate _{( Mg2SiO4 , MgSiO3, etc.} ) _, calcium silicate ( _Ca2・SiO ₄ etc.) Aluminum calcium silicate (Al ₂ O ₃・CaO・2SiO ₂ etc.), magnesium calcium silicate (CaMgSiO ₄ ), zirconium oxide (ZrO ₂ ), zirconium hydroxide [ZrO(OH) ₂・nH ₂ 0], zirconium carbonate [Zr(CO ₃ ) ₂ ], zinc acrylate, zinc methacrylate, hydrogen that corrects charge like various zeolites, crystalline aluminosilicates containing alkali metals or alkaline earth metals, etc. can do. These inorganic fillers can be used alone or in combination of two or more.

As the vulcanizing agent, an organic peroxide or a sulfur-based vulcanizing agent can be blended. Examples of organic peroxides include benzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, 2,5-dimethyl-2, 5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane- 3,1,3-bis(t-butylperoxypropyl)benzene, di-t-butylperoxy-diisopropylbenzene, t-butylperoxybenzene, 2,4-dichlorobenzoyl peroxide, 1,1-di- t-Butylperoxy-3,3,5-trimethylsiloxane, n-butyl-4,4-di-t-butylperoxyvalerate, etc. can be blended. Among these organic peroxides, dicumyl peroxide, t-butylperoxybenzene, and di-t-butylperoxy-diisopropylbenzene are preferred. Further, as the sulfur-based vulcanizing agent, for example, sulfur, morpholine disulfide, etc. can be blended. Among these sulfur-based vulcanizing agents, sulfur is preferred.

As the vulcanization accelerator, sulfenamide type, thiazole type, thiuram type, thiourea type, guanidine type, dithiocarbamate type, aldehyde-amine type, aldehyde-ammonia type, etc. can be blended.

Examples of sulfenamides include CBS (N-cyclohexyl-2-benzothiazylsulfenamide), TBBS (N-t-butyl-2-benzothiazylsulfenamide), N,N-dicyclohexyl-2 Examples include sulfenamide compounds such as -benzothiazylsulfenamide, N-oxydiethylene-2-benzothiazylsulfenamide, and N,N-diisopropyl-2-benzothiazolesulfenamide.

Examples of the thiazole type include MBT (2-mercaptobenzothiazole), MBTS (dibenzothiazyl disulfide), sodium salt, zinc salt, copper salt, cyclohexylamine salt, 2-(2,4- Examples include dinitrophenyl)mercaptobenzothiazole, 2-(2,6-diethyl-4-morpholinothio)benzothiazole, and the like.

Examples of the thiuram type include TMTD (tetramethylthiuram disulfide), tetraethylthiuram disulfide, tetramethylthiuram monosulfide, dipentamethylenethiuram disulfide, dipentamethylenethiuram monosulfide, dipentamethylenethiuram tetrasulfide, dipentamethylenethiuram hexa Examples include sulfide, tetrabutylthiuram disulfide, pentamethylenethiuram tetrasulfide, and the like.

Examples of thiourea compounds include thiourea compounds such as thiacarbamide, diethylthiourea, dibutylthiourea, trimethylthiourea, and diorthotolylthiourea.

Examples of guanidine compounds include guanidine compounds such as diphenylguanidine, diorthotolylguanidine, triphenylguanidine, orthotolyl biguanide, and diphenylguanidine phthalate.

Examples of dithiocarbamic acids include zinc ethylphenyldithiocarbamate, zinc butylphenyldithiocarbamate, sodium dimethyldithiocarbamate, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc diamyldithiocarbamate, and dipropyldithiocarbamate. Zinc, complex salt of zinc pentamethylene dithiocarbamate and piperidine, zinc hexadecyl isopropyldithiocarbamate, zinc octadecyl isopropyldithiocarbamate, zinc dibenzyldithiocarbamate, sodium diethyldithiocarbamate, piperidine pentamethylene dithiocarbamate, selenium dimethyldithiocarbamate, diethyldithiocarbamic acid Examples include dithiocarbamic acid compounds such as tellurium and cadmium diamyldithiocarbamate.

Examples of the aldehyde-amine type or aldehyde-ammonia type include an acetaldehyde-aniline reaction product, a butyraldehyde-aniline condensate, hexamethylenetetramine, and an acetaldehyde-ammonia reaction product.

As the vulcanization accelerating aid, stearic acid, zinc white (zinc oxide), etc. can be blended.

As the anti-aging agent, amine-based, phenol-based, imidazole-based compounds, carbamate metal salts, wax, etc. can be blended.

Softeners include process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt, petroleum softeners such as vaseline, fatty oil softeners such as castor oil, linseed oil, rapeseed oil, and coconut oil; tall oil, sub , waxes such as beeswax, carnauba wax, and lanolin; fatty acids such as linoleic acid, palmitic acid, stearic acid, and lauric acid; and the like. By incorporating a softener, the kneading processability can be further improved.

Plasticizers include DMP (dimethyl phthalate), DEP (diethyl phthalate), DBP (dibutyl phthalate), DHP (diheptyl phthalate), DOP (dioctyl phthalate), DINP (diisononyl phthalate), DIDP (phthalate). diisodecyl acid), BBP (butylbenzyl phthalate), DLP (dilauryl phthalate), DCHP (dicyclohexyl phthalate), hydrophthalic anhydride, DOZ (di-2-ethylhexyl azelate), DBS (dibutyl sebacate), DOS (dioctyl sebacate), acetyl triethyl citrate, acetyl tributyl citrate, DBM (dibutyl maleate), DOM (2-ethylhexyl maleate), DBF (dibutyl fumarate), etc. can be blended.

As the scorch inhibitor, organic acids such as phthalic anhydride, salicylic acid and benzoic acid; nitroso compounds such as N-nitrosodiphenylamine; N-cyclohexylthiophthalimide; etc. can be blended.

The rubber composition of the present invention can be produced using the method described below, and the above-mentioned compounding method can be produced using a kneading machine such as an open kneading machine such as a roll or a closed kneading machine such as a Banbury mixer. It can be obtained by kneading a compound, and can be applied to various rubber products by performing vulcanization at 140 to 190°C for 5 to 120 minutes after molding.

(2. Tires)
The rubber composition of the present invention can be used particularly for tire components such as tire treads, undertreads, carcass, sidewalls, and bead parts.

The tire of the present invention has low heat generation properties, thereby reducing the rolling resistance of the tire and having excellent fuel efficiency. In addition, since it has excellent resistance to high loads, it can be suitably used as a tire for heavy-duty vehicles such as trucks, buses, aircraft, or industrial vehicles (heavy-duty tires).

(3. Low heat generation agent)
The present invention includes inventions relating to a low heat build-up agent for rubber containing the above-mentioned tetrazine compound and hydrazide compound.

The blending amount of the hydrazide compound with respect to the tetrazine compound is preferably 30 to 300 parts by mass, more preferably 50 to 200 parts by mass, and 75 to 125 parts by mass relative to 100 parts by mass of the tetrazine compound. It is more preferable to do so.

It is preferable that the heat generating agent of the present invention is, for example, an embodiment consisting only of a tetrazine compound and a hydrazide compound (first embodiment).

The second embodiment preferably contains silica and carbon black in addition to the tetrazine compound and the hydrazide compound. At this time, the compounding amount of the tetrazine compound and the hydrazide compound is preferably 0.2 to 7 parts by mass, and 1 to 7 parts by mass, respectively, per 100 parts by mass of the silica and carbon black in total. It is more preferable to use parts by mass. At this time, the blending ratio of silica and carbon black is preferably 20 to 60 parts by mass, more preferably 30 to 50 parts by mass, of carbon black to 100 parts by mass of silica.

Further, in the second embodiment, it is also preferable to add other compounding agents within a range that does not impair the purpose and effects of the present invention. Coupling agents, inorganic fillers other than carbon black and silica, vulcanizing agents, vulcanization accelerators, vulcanization accelerators, anti-aging agents, softeners, plasticizers, anti-scorch agents, anti-ozonants, blowing agents, Examples include compounding agents commonly used in the rubber industry, such as vulcanization retarders.

Although the embodiments of the present invention have been described above, the present invention is not limited to these examples at all, and it goes without saying that the present invention can be implemented in various forms without departing from the gist of the present invention.

Hereinafter, embodiments of the present invention will be described in more detail based on Examples, but the present invention is not limited thereto.

Examples 1 and 2 and Comparative Examples 1 to 3
Each component listed in Step A of Table 1 below was mixed in the proportions (parts by mass), and kneaded for 5 minutes using a Banbury mixer while adjusting the rotation speed so that the maximum temperature of the mixture was 160°C.
After curing until the temperature of the mixture becomes 80°C or less, add each component listed in Step B of Table 1 in the proportion (parts by mass) and adjust the mixture so that the maximum temperature is 110°C or less. Each rubber composition was manufactured by kneading.

Low heat generation (tan δ index) test The rubber compositions (test compositions) prepared in each example and comparative example were tested at a temperature of 40°C, a dynamic strain of 5%, and a frequency using a viscoelasticity measuring device (manufactured by Metravib). Tan δ was measured at 15 Hz, and the low heat generation index was calculated based on the following formula. Note that the larger the value of the low heat generation index, the lower the heat generation and the smaller the hysteresis loss.
The results are shown in Table 1.
formula:
Low pyrogenicity index = {(tan δ of the test composition of Comparative Example 1)/(tan δ of each test composition)}×100

Durability test The test composition was subjected to repeated strain at an elongation rate of 100% using a Dematcher tester in accordance with JIS K6260, and the number of times it took to break (number of times of breakage) was measured, and the result was calculated using the following formula. Based on this, the durability index was calculated. The larger the index, the more excellent the durability.
The results are shown in Table 1.
formula:
Durability index = {(Number of breaks for each test composition)/(Number of breaks for test composition of Comparative Example 1)}×100

※１：宇部興産株式会社製、商品名「ＢＲ１５０Ｂ」
※２：旭化成株式会社製、商品名「タフデン２０００Ｒ」
※３：ＧＵＡＮＧＫＥＮ ＲＵＢＢＥＲ社製、ＴＳＲ－２０
※４：東ソー・シリカ株式会社製、商品名「Ｎｉｐｓｉｌ(銘柄ＡＱ)」
※５：Evonik Industries AG製、商品名「Ｓｉ６９」
※６：東海カーボン株式会社製、商品名「＃８０」
※７：川口化学工業株式会社製、商品名「Ａｎｔａｇｅ ６Ｃ」
※８：Schill + Seilacher "Struktol" GmbH社製、商品名「ストラクトールHT254」
※９：堺化学工業株式会社製、酸化亜鉛 銘柄「１種」
※１０：Sichuan Tianyu Grease Chemical Co., Ltd. 製
※１１：３，６－ビス（２－ピリジル）－１，２，４，５－テトラジン、大塚化学株式会社製
※１２：３－ヒドロキシ－Ｎ'－(１,３－ジメチルブチリデン)－２－ナフトエ酸ヒドラジド、大塚化学株式会社製
※１３：大内新興化学工業株式会社製、商品名「ノクセラーＤ」
※１４：大内新興化学工業株式会社製、商品名「ノクセラーＣＺ－Ｇ」
※１５：細井化学工業株式会社製、商品名「ＨＫ２００－５」

*1: Manufactured by Ube Industries Co., Ltd., product name "BR150B"
*2: Manufactured by Asahi Kasei Corporation, product name “Tufden 2000R”
*3: Manufactured by GUANGKEN RUBBER, TSR-20
*4: Manufactured by Tosoh Silica Co., Ltd., product name “Nipsil (brand AQ)”
*5: Manufactured by Evonik Industries AG, product name “Si69”
*6: Manufactured by Tokai Carbon Co., Ltd., product name "#80"
*7: Manufactured by Kawaguchi Chemical Industry Co., Ltd., product name “Antage 6C”
*8: Manufactured by Schill + Seilacher "Struktol" GmbH, product name "Struktol HT254"
*9: Manufactured by Sakai Chemical Industry Co., Ltd., zinc oxide brand “Type 1”
*10: Manufactured by Sichuan Tianyu Grease Chemical Co., Ltd. *11: 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine, manufactured by Otsuka Chemical Co., Ltd. *12: 3-hydroxy-N '-(1,3-dimethylbutylidene)-2-naphthoic acid hydrazide, manufactured by Otsuka Chemical Co., Ltd. *13: Manufactured by Ouchi Shinko Chemical Co., Ltd., product name "Noxeler D"
*14: Manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., product name “Noxeler CZ-G”
*15: Manufactured by Hosoi Chemical Industry Co., Ltd., product name “HK200-5”

By containing a predetermined tetrazine compound and a hydrazide compound in a predetermined ratio, the rubber composition of the present invention has the same level of durability but has even better low heat generation properties, and is suitable for use in heavy-duty tires. It can be suitably used as a material.

Claims (7)

Rubber components including natural rubber and synthetic diene rubber, silica, carbon black, 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine or its salt, and 3-hydroxy-N'-( 1,3-dimethylbutylidene)-2-naphthoic acid hydrazide,
The blending amount of each component is based on a total of 100 parts by mass of the natural rubber and the synthetic diene rubber,
the silica is 15 to 120 parts by mass,
5 to 80 parts by mass of the carbon black,
0.05 to 10 parts by mass of 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine or a salt thereof,
A rubber composition comprising 0.05 to 10 parts by mass of 3-hydroxy-N'-(1,3-dimethylbutylidene)-2-naphthoic acid hydrazide. The composition according to claim 1, wherein the content of the natural rubber is 10 to 80% by mass in a total of 100% by mass of the natural rubber and the synthetic diene rubber. The composition according to claim 1 or 2, wherein the synthetic diene rubber is at least one selected from the group consisting of isoprene rubber, styrene-butadiene rubber, and butadiene rubber. The composition according to any one of claims 1 to 3, which is used for a tread portion of a tire. A tire manufactured using the composition according to any one of claims 1 to 4. The tire according to claim 5, which is for heavy loads. 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine or a salt thereof, and 3-hydroxy-N'-(1,3-dimethylbutylidene)-2-naphthoic acid hydrazide, Low heat generation agent for rubber.