JP2014237788A - Rubber composition and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition capable of improving low heat build-up performance while suppressing deterioration in physical properties such as tear strength.SOLUTION: The rubber composition contains 0.1-10 pts.mass of at least one thiohydrazide compound, which has an average particle diameter of 100 μm or less and is represented by formula (1) or formula (2), and 30-150 pts.mass of a filler, based on 100 pts.mass of a rubber component containing a diene rubber. In the formulae, R, R, and Reach represent a hydrogen atom or an optionally substituted C1-C15 hydrocarbon group, and X represents a hydrogen atom, an amino group, a hydroxyl group, a C1-C15 hydrocarbon group, or a group represented by formula (3) or formula (4).

Description

  The present invention relates to a rubber composition and a pneumatic tire using the same.

  Conventionally, for example, in rubber compositions used in pneumatic tires, in order to reduce rolling resistance, it has been required to make it difficult to generate heat, that is, to improve low heat generation performance, and various studies have been made. Yes. For example, in Patent Document 1, by adding a thiosulfuric acid compound having a specific structure and a median diameter of 10 to 100 μm to a rubber composition, the viscoelastic properties of the vulcanized rubber are improved and the low heat generation performance is improved. Is disclosed. In this document, the particle diameter of the thiosulfate compound is specified in order to improve the viscoelastic characteristics by reducing the particle diameter.

  On the other hand, Patent Document 2 discloses that in a rubber composition for a belt such as a conveyor belt, a hydrazide compound having a specific structure is blended together with a terminal-modified butadiene rubber in order to reduce energy loss. However, this document does not disclose the point of incorporating a thiohydrazide compound.

  Patent Documents 3 and 4 disclose that a compound having a thiohydrazide structure is blended in a rubber composition. However, in Patent Document 3, a —C (═NH) — group bonded to a thiohydrazide group is essential, and in Patent Document 4, a carbonyl group bonded to a thiohydrazide group, that is, —C (═O). -Is essential, and a specific hydrazide compound described later is not disclosed. Moreover, these literatures use the said compound as an anti-aging agent, and are not mentioned about the low heat_generation | fever performance.

JP 2012-107232 A JP 2006-104372 A JP 2001-139728 A Japanese Patent Laid-Open No. 11-228737

  The present inventor has found that the low heat generation performance can be improved by blending a thiohydrazide compound having a specific structure into a rubber composition together with a filler. However, since the thiohydrazide compound is highly polar and difficult to disperse, a new problem has arisen in that physical properties such as tearing force are reduced.

  Then, an object of this invention is to provide the rubber composition which can improve low heat generation performance, suppressing physical property fall, such as tearing force.

The rubber composition according to the present invention is composed of a compound represented by the following general formula (1) and a compound represented by the following general formula (2) with respect to 100 parts by mass of the rubber component containing the diene rubber. It contains at least one selected thiohydrazide compound having an average particle size of 100 μm or less and 0.1 to 10 parts by mass and a filler of 30 to 150 parts by mass.

（式中のＹは、炭素数が１〜１５である２価の炭化水素基を示す。）］ [Wherein, R ¹ , R ² and R ³ each independently represent a hydrogen atom or an optionally substituted hydrocarbon group having 1 to 15 carbon atoms, and X represents a hydrogen atom or an amino group. , A hydroxyl group, a hydrocarbon group having 1 to 15 carbon atoms, or a group represented by the following formula (3) or formula (4).

(Y in the formula represents a divalent hydrocarbon group having 1 to 15 carbon atoms.)]

  According to the present invention, low heat generation performance can be improved by blending a thiohydrazide compound having a specific structure into a rubber composition together with a filler. Further, by using a thiohydrazide compound having a reduced average particle size of 100 μm or less, deterioration of physical properties such as tearing force can be suppressed.

  Hereinafter, matters related to the implementation of the present invention will be described in detail.

  The rubber composition according to this embodiment includes at least one thiohydrazide compound selected from the group consisting of compounds represented by the above general formula (1) or (2) as a rubber component containing a diene rubber, It is formed by blending with a filler.

  The diene rubber as the rubber component is not particularly limited. Examples of usable diene rubber include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene rubber, butadiene-isoprene rubber, and styrene-butadiene. -Isoprene rubber, nitrile rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR) and the like can be mentioned, and these can be used alone or in combination of two or more. More preferably, it is NR, SBR, BR, or a blend rubber of two or more thereof. The rubber component is basically composed only of diene rubber, but non-diene rubber may be blended within a range that does not impair the effect (for example, 20% by mass or less).

  In one embodiment, the rubber component preferably includes natural rubber. For example, in 100 parts by mass of the rubber component, 10 parts by mass or more of natural rubber may be contained, and 50 parts by mass or more of natural rubber may be contained.

  The thiohydrazide compound used in the present embodiment is a thiohydrazide derivative represented by the above formula (1) or (2), and may be a compound represented by the formula (1) alone or represented by the formula (2). The compounds may be used alone or in combination.

In the above formula (1) and ^(2), R 1, ^{R 2} and ^{R 3} each independently represent a hydrogen atom or an optionally substituted hydrocarbon group of 1 to 15 carbon atoms. The hydrocarbon group is preferably a saturated or unsaturated linear or branched alkyl group, a saturated or unsaturated cycloalkyl group, or an aromatic hydrocarbon group. As a substituent, what contains hetero atoms, such as an oxygen atom and a nitrogen atom, is mentioned, Preferably they are a hydroxyl group and / or an amino group. As an alkyl group, it is preferable that it is C1-C10, More preferably, it is 1-6, More preferably, it is 1-4. Specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, and an n-hexyl group. The cycloalkyl group preferably has 3 to 15 carbon atoms, and more preferably 3 to 10 carbon atoms. Specific examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cyclooctyl group, and the like, and an alkyl group bonded to a ring carbon atom such as a 2-methylcyclopropyl group. And the like. The cycloalkyl group is not limited to a monovalent group obtained by removing a hydrogen atom from a ring carbon atom, and may be a group formed by removing a hydrogen atom from a side chain such as a cyclopropylmethyl group. . The aromatic hydrocarbon group preferably has 6 to 15 carbon atoms, and more preferably 6 to 10 carbon atoms. Specific examples of the aromatic hydrocarbon group include an aryl group such as a phenyl group, a naphthyl group, a tolyl group, a xylyl group, a mesityl group, a cumenyl group, and an anthryl group, and an aralkyl group such as a benzyl group and a phenethyl group. Can be mentioned.

In the formulas (1) and (2), X represents a hydrogen atom, an amino group, a hydroxyl group, a hydrocarbon group having 1 to 15 carbon atoms, or a group represented by the above formula (3) or formula (4). Show. The amino group includes a primary, secondary or tertiary amino group. In addition, in the case of a secondary or tertiary amino group, the number of carbon atoms of the hydrocarbon groups as substituents is preferably 15 or less in total. Examples of the hydrocarbon group having 1 to 15 carbon atoms include a saturated or unsaturated linear or branched alkyl group, a saturated or unsaturated cycloalkyl group, and an aromatic hydrocarbon group, and R ¹ , R same as the hydrocarbon groups mentioned in ² and R ³ may be mentioned as preferred. When X is a group represented by the formula (3) or (4), it is a bifunctionalized thiohydrazide structure. Usually, the group represented by the formula (3) is represented by the formula (1). The group represented by formula (4) is introduced as X of the compound represented by formula (2), and is introduced as X of the compound represented by formula (2).

  Y in the formulas (3) and (4) represents a divalent hydrocarbon group having 1 to 15 carbon atoms, for example, a divalent alkyl group, a divalent cycloalkyl group, or a divalent aromatic group. A hydrocarbon group is mentioned. The divalent alkyl group (that is, alkanediyl group) may be linear or branched, and preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms. Specific examples of the divalent alkyl group include divalent groups generated by further removing one hydrogen atom from those listed as specific examples of the monovalent alkyl group. The divalent cycloalkyl group (that is, cycloalkanediyl group) preferably has 3 to 15 carbon atoms, and more preferably 3 to 10 carbon atoms. Specific examples of the divalent cycloalkyl group include divalent groups generated by further removing one hydrogen atom from those listed as specific examples of the monovalent cycloalkyl group. The divalent aromatic hydrocarbon group preferably has 6 to 15 carbon atoms, more preferably 6 to 10 carbon atoms. Specific examples of the divalent aromatic hydrocarbon group include divalent groups produced by removing one hydrogen atom from those listed as specific examples of the monovalent aromatic hydrocarbon group ( For example, an arylene group or an aralkyldiyl group) may be mentioned.

Incidentally, ^R 1, ^{R 2} and ^{R 3} in the formula (3) and (4) is the same as ^R 1, ^{R 2} and ^{R 3} in formula (1) and (2).

In the above formula, R ¹ , R ² and R ³ are each independently preferably a hydrogen atom or an alkyl group having 1 to 15 carbon atoms, and X is preferably an amino group.

  Specific examples of the thiohydrazide compound include the following. These compounds can be used alone or in combination of two or more.

[Compound represented by Formula (1)]
Examples of X = amino group: acetone thiosemicarbazone, formaldehyde-3-thiosemicarbazone, acetaldehyde-3-thiosemicarbazone, heptaldehyde-3-thiosemicarbazone, cyclohexylmethylketone-3-thiosemi Carbazone, benzylmethylketone-3-thiosemicarbazone, p-hydroxybenzaldehyde-3-thiosemicarbazone, acetaldehyde-4-methyl-3-thiosemicarbazone, heptaaldehyde-4-methyl-3-thiosemi Carbazone, cyclohexyl methyl ketone-4-methyl-3-thiosemicarbazone, benzylmethylketone-4-methyl-3-thiosemicarbazone, p-hydroxybenzaldehyde-4-methyl-3-thiosemicarbazone, acetaldehyde -4-butyl-3-thiocete Carbazone, heptaldehyde-4-butyl-3-thiosemicarbazone, cyclohexylmethylketone-4-butyl-3-thiosemicarbazone, benzylmethylketone-4-butyl-3-thiosemicarbazone, p-hydroxybenzaldehyde -4-butyl-3-thiosemicarbazone, acetaldehyde-4-phenyl-3-thiosemicarbazone, heptaaldehyde-4-phenyl-3-thiosemicarbazone, cyclohexylmethylketone-4-phenyl-3-thio Semicarbazone, benzyl methyl ketone-4-phenyl-3-thiosemicarbazone, p-hydroxybenzaldehyde-4-phenyl-3-thiosemicarbazone;
Examples of X = hydrocarbon groups: N′-methylidenehexanoic acid-3-thiohydrazide, N′-ethylidenehexanoic acid-3-thiohydrazide, N ′-(1-methylethylidene) hexanoic acid-3-thiohydrazide ;
Examples of X = hydrogen atom: N′-methylidenemethanoic acid-3-thiohydrazide, N′-ethylidenemethanoic acid-3-thiohydrazide, N′-heptylidenemethanoic acid-3-thiohydrazide, N ′-(1 -Methylethylidene) methanoic acid-3-thiohydrazide, N '-(1-cyclohexylethylidene) methanoic acid-3-thiohydrazide, N'-(1-phenylethylidene) methanoic acid-3-thiohydrazide, N '-( 4-hydroxyphenylmethylidene) methanoic acid-3-thiohydrazide;
Examples of X = hydroxyl group: N′-methylidenehydrazinecarbothio O-acid, N′-ethylidenehydrazinecarbothio O-acid, N′-heptylidenehydrazinecarbothio O-acid, N ′-(1- Methylethylidene) hydrazinecarbothio O-acid, N '-(1-cyclohexylethylidene) hydrazinecarbothio O-acid, N'-(1-phenylethylidene) hydrazinecarbothio O-acid, N '-(4-hydroxyphenyl) Methylidene) hydrazinecarbothio O-acid;
X = examples of groups represented by formula (3): N ′ (1), N ′ (5) -di (1-methylethylidene) pentanebis (thiohydrazide), N ′ (1), N ′ (3 ) -Di (1-methylethylidene) benzene-1,3-bis (thiohydrazide).

[Compound represented by Formula (2)]
Examples of X = amino group: thiosemicarbazide, 2-methyl-3-thiosemicarbazide, 4-methyl-3-thiosemicarbazide, 4-ethyl-3-thiosemicarbazide, 4-butyl-3-thiosemicarbazide, 4-tert -Butyl-3-thiosemicarbazide, 4-hexyl-3-thiosemicarbazide, 4-allyl-3-thiosemicarbazide, 4-phenyl-3-thiosemicarbazide, 4-benzyl-3-thiosemicarbazide, 2-ethyl-3- Thiosemicarbazide, 2-cyclohexyl-3-thiosemicarbazide, 2-phenyl-3-thiosemicarbazide, 2-methyl-4-ethyl-3-thiosemicarbazide, 2-ethyl-4-ethyl-3-thiosemicarbazide, 2-cyclohexyl -4-ethyl-3-thiosemicarbazide, 2-phenyl-4-ethyl Ru-3-thiosemicarbazide;
Examples of X = hydrogen atom: methanoic acid-3-thiohydrazide, N-methylmethanoic acid-3-thiohydrazide, N-ethylmethanoic acid-3-thiohydrazide, N-cyclohexylmethanoic acid-3-thiohydrazide, N- Phenylmethanoic acid-3-thiohydrazide;
Examples of X = hydrocarbon group: hexanoic acid-3-thiohydrazide, N-methylhexanoic acid-3-thiohydrazide, N-ethylhexanoic acid-3-thiohydrazide, N-cyclohexylhexanoic acid-3-thiohydrazide, N-phenylhexanoic acid-3-thiohydrazide;
Examples of X = hydroxyl group: hydrazine carbothio O-acid, N-methyl hydrazine carbothio O-acid, N-ethyl hydrazine carbothio O-acid, N-cyclohexyl hydrazine carbothio O-acid, N-phenylhydrazine carbo Thio O-acid;
X = examples of groups represented by formula (4): succinic acid dithiohydrazide, adipic acid dithiohydrazide, phthalic acid dithiohydrazide, isophthalic acid dithiohydrazide, terephthalic acid dithiohydrazide.

  In the present embodiment, as the thiohydrazide compound, one having an average particle size of 100 μm or less is used. By using a material having such a small particle size, the dispersibility of the thiohydrazide compound can be improved, and deterioration of physical properties such as tearing force can be suppressed. The average particle size is preferably 75 μm or less, more preferably 50 μm or less. Although the minimum of an average particle diameter is not specifically limited, It is preferable that it is 1 micrometer or more, More preferably, it is 10 micrometers or more.

The average particle diameter is a value measured by a laser diffraction / scattering method. In the following examples, a laser diffraction particle size distribution measuring apparatus “manufactured by Shimadzu Corporation” using a red semiconductor laser (wavelength 680 nm) as a light source is used. The average value of the particle size distribution measured by “SALD-2200” (the value of 10 ^μ when the average value of the particle size distribution on the logarithmic scale (volume basis) is μ) is defined as the average particle diameter.

  The thiohydrazide compound having such a small particle diameter is not particularly limited, and can be obtained, for example, by pulverizing a commercially available thiohydrazide compound or a thiohydrazide compound synthesized by a known method. The method for crushing the thiohydrazide compound is not particularly limited, and examples thereof include crushing using a roll mill, a ball mill, and a turbo mill.

  It is preferable that the compounding quantity of the said thiohydrazide compound is 0.1-10 mass parts with respect to 100 mass parts of rubber components. By setting it as such a compounding quantity, the improvement effect of low heat generation performance can be heightened. The compounding amount of the thiohydrazide compound is more preferably 0.3 to 8 parts by mass, still more preferably 0.5 to 5 parts by mass.

  As the filler to be blended in this embodiment, carbon black and / or silica as a reinforcing filler is preferably used. More preferably, carbon black alone or a combination of carbon black and silica is used.

Carbon black is not particularly limited, and various known varieties can be used. For example, when used for tire tread rubber, those having a nitrogen adsorption specific surface area (N ₂ SA) (JIS K6217-2) of 70 to 150 m ² / g are preferably used. Specifically, SAF class (N100 series), ISAF class (N200 series), HAF class (N300 series) (both ASTM grade) are preferably used.

The silica is not particularly limited, but wet silica such as wet precipitation silica or wet gel silica is preferably used. BET specific surface area of the silica (measured according to BET method according to JIS K6430) is not particularly limited, is preferably 90~250m ² / g, more preferably 150~220m ² / g.

  It is preferable that the compounding quantity of a filler is 30-150 mass parts with respect to 100 mass parts of rubber components, More preferably, it is 30-120 mass parts, More preferably, it is 40-100 mass parts. It is preferable that the compounding quantity of carbon black is 3-150 mass parts, More preferably, it is 10-100 mass parts, More preferably, it is 10-50 mass parts, and it is 20-50 mass parts as one embodiment. Good. It is preferable that the compounding quantity of a silica is 100 mass parts or less, for example, 10-80 mass parts may be sufficient, and 20-50 mass parts may be sufficient.

  When silica is blended as a filler, a silane coupling agent may be blended in order to improve the dispersibility of silica. Although the compounding quantity of a silane coupling agent is not specifically limited, It is preferable that it is 2-25 mass parts with respect to 100 mass parts of silica. The silane coupling agent is not particularly limited. For example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-triethoxysilylpropyl) disulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis Sulfide silane coupling agents such as (4-triethoxysilylbutyl) disulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) disulfide; 3-mercaptopropyltrimethoxysilane, 3- Mercaptosilane coupling agents such as mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyldimethylmethoxysilane, mercaptoethyltriethoxysilane; Examples thereof include protected mercaptosilane coupling agents such as tanoylthio-1-propyltriethoxysilane and 3-propionylthiopropyltrimethoxysilane. These can be used alone or in combination of two or more.

  In the rubber composition according to the present embodiment, in addition to the above components, zinc oxide, stearic acid, oil, anti-aging agent, softener, wax, vulcanizing agent, vulcanization accelerator, etc. Various commonly used additives can be blended. Examples of the vulcanizing agent include sulfur components such as powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur. Although not particularly limited, the blending amount thereof is 100 parts by mass of the rubber component. It is preferable that it is 0.1-10 mass parts with respect to it, More preferably, it is 0.5-5 mass parts. Moreover, as a compounding quantity of a vulcanization accelerator, it is preferable that it is 0.1-7 mass parts with respect to 100 mass parts of said rubber components, More preferably, it is 0.5-5 mass parts.

  The rubber composition can be prepared by kneading according to a conventional method using a commonly used Banbury mixer, kneader, roll, or other mixer. For example, in the first mixing stage, the rubber component is added and mixed with the thiohydrazide compound and the filler together with other additives except the vulcanizing agent and the vulcanization accelerator, and then the resulting mixture is finally mixed. A rubber composition can be prepared by adding and mixing a vulcanizing agent and a vulcanization accelerator in stages.

  The rubber composition according to this embodiment can be used for various rubber compositions that form rubber parts such as pneumatic tires, vibration-proof rubbers, and conveyor belts. Preferably, it is used for tires, and rubber parts of various pneumatic tires can be constituted by vulcanization molding at 140 to 180 ° C., for example, according to a conventional method. As one embodiment, it is preferably used for tread rubber and / or sidewall rubber of a pneumatic tire, and rolling resistance can be reduced to produce a tire with excellent fuel efficiency.

In the rubber composition according to this embodiment, the thiohydrazide compound interacts with a functional group on the surface of the filler (for example, carbonyl or carboxyl on the surface of carbon black, or a silanol group on the surface of silica). Dispersibility can be improved, so that the loss factor tan δ can be reduced and the low heat generation performance can be improved. More specifically, the thiohydrazide compound of the above formula (1) is considered to be physically bonded because of its close polarity to carbonyl and carboxyl on the surface of carbon black. In the thiohydrazide compound of the above formula (2), it is considered that the amino group (—NH ₂ ) reacts with the carbonyl on the surface of the carbon black to be chemically bonded. As a result, the surface of the carbon black is modified with a thiohydrazide compound, so that the dispersibility of the carbon black is improved.

  When natural rubber is used as the diene rubber, the natural rubber generally contains a protein or phospholipid at the terminal, and these carbonyls can react with the thiohydrazide compound. Therefore, since the polar group derived from the thiohydrazide compound is introduced at the end of the natural rubber, the dispersibility of the filler such as carbon black is further improved, and tan δ can be reduced.

  In addition, since the thiohydrazide compound is highly polar and difficult to disperse in the diene rubber, it may be a factor of physical properties such as tearing force. By reducing the particle size with, the dispersibility of the thiohydrazide compound can be improved, and deterioration of physical properties such as tearing force can be suppressed. For this reason, for example, when used in tread rubber for pneumatic tires, especially for heavy duty tires such as trucks and buses, fuel efficiency performance is improved by reducing rolling resistance while suppressing reduction in cut resistance and chip resistance. can do.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

  Using a Banbury mixer, according to the composition (parts by mass) shown in Table 1 below, first, in the first mixing stage, components other than sulfur and vulcanization accelerator are added and mixed (discharge temperature = 160 ° C.), and then obtained. In the final mixing stage, sulfur and a vulcanization accelerator were added to and mixed with the resulting mixture (discharge temperature = 90 ° C.) to prepare a tire tread rubber composition. The details of each component in Table 1 are as follows.

・ NR: RSS # 3
・ Carbon black: SAF, “Seast 9” manufactured by Tokai Carbon Co., Ltd.
Anti-aging agent: “Antigen 6C” manufactured by Sumitomo Chemical Co., Ltd.
・ Stearic acid: “Beadstearic acid” manufactured by NOF Corporation
・ Zinc oxide: “Zinc flower 1” manufactured by Mitsui Mining & Smelting Co., Ltd.
・ Vulcanization accelerator: “Soxinol CZ” manufactured by Sumitomo Chemical Co., Ltd.
・ Sulfur: “Powder sulfur” manufactured by Tsurumi Chemical Co., Ltd.

[Thiohydrazide compounds]
ATS: acetone thiosemicarbazone, manufactured by Tokyo Chemical Industry Co., Ltd. TS: thiosemicarbazide, manufactured by Tokyo Chemical Industry Co., Ltd. 2-MTS: 2-methyl-3-thiosemicarbazide, manufactured by Sigma Aldrich Japan

  Among these thiohydrazide compounds, two types of ATS were used for the test, an unground product (average particle size = 150 μm) and a ground product (average particle size = 38 μm). For other thiohydrazide compounds, only the pulverized product was subjected to the test. The thiohydrazide compound was pulverized using a ball mill at a temperature equal to or lower than the melting point of each thiohydrazide compound (for example, 175 ° C. for ATS, 184 ° C. for TS, and 174 ° C. for 2-MTS).

  About each obtained rubber composition, it vulcanized | cured at 150 degreeC * 30 minute (s), the test piece was produced, and rolling resistance performance and tearing force were evaluated. Each evaluation method is as follows.

Rolling resistance performance: tan δ was measured using a viscoelasticity tester manufactured by Toyo Seiki Co., Ltd. under conditions of initial strain 10%, dynamic strain ± 1%, frequency 50 Hz, temperature 60 ° C., Comparative Example 1 It was shown as an index with the value of 100 as 100. The smaller the index, the smaller the tan δ at 60 ° C., and the less the heat is generated, which means that the rolling resistance performance (ie, low fuel consumption) is excellent.

・ Tearing force: punched with a crescent shape defined in JIS K6252 and made a test sample with a 0.50 ± 0.08 mm notch in the center of the indentation. The test sample was 500 mm by a tensile tester manufactured by Shimadzu Corporation. The tear test was conducted at a pulling rate of / min. The value of Comparative Example 1 is expressed as an index with a value of 100, and the higher the value, the higher the tearing force and the better.

  The results are as shown in Table 1, and in Comparative Example 2 in which an unground thiohydrazide compound was blended with respect to Comparative Example 1 as a control, although the rolling resistance performance was excellent, the tearing force was reduced. It was. On the other hand, the rolling resistance performance is improved without being accompanied by a decrease in tearing force as compared with Comparative Example 1 in Examples 1 to 3 in which the thiohydrazide compound reduced in particle size by pulverization is blended. The rolling resistance performance was superior to that of Comparative Example 2.

Claims (4)

It is at least one selected from the group consisting of a compound represented by the following general formula (1) and a compound represented by the following general formula (2) with respect to 100 parts by mass of the rubber component containing the diene rubber. A rubber composition comprising 0.1 to 10 parts by mass of a thiohydrazide compound having an average particle size of 100 μm or less and 30 to 150 parts by mass of a filler.

[Wherein, R ¹ , R ² and R ³ each independently represent a hydrogen atom or an optionally substituted hydrocarbon group having 1 to 15 carbon atoms, and X represents a hydrogen atom or an amino group. , A hydroxyl group, a hydrocarbon group having 1 to 15 carbon atoms, or a group represented by the following formula (3) or formula (4).

(Y in the formula represents a divalent hydrocarbon group having 1 to 15 carbon atoms.)] The R ¹ , R ² and R ³ in the formula each independently represent a hydrogen atom or an alkyl group having 1 to 15 carbon atoms, and X represents an amino group. Rubber composition.   The rubber composition according to claim 1 or 2, wherein the filler contains 3 to 150 parts by mass of carbon black.   The pneumatic tire which uses the rubber composition of any one of Claims 1-3.