JP7241748B2 - Rubber composition, rubber composition for tire tread, and tire - Google Patents

Description

TECHNICAL FIELD The present invention relates to a rubber composition, a tire tread rubber composition, and a tire.

BACKGROUND ART In recent years, the demand for low fuel consumption of automobiles is becoming more severe in connection with the movement of global carbon dioxide emission regulations accompanying the social demand for energy saving and the growing interest in environmental problems. Therefore, as a tire rubber composition for use in tire treads and the like, a rubber composition having a low tan δ and excellent low heat build-up is desired.

Therefore, it is currently desired to develop a technology that can improve wear resistance in addition to low fuel consumption. As one of these techniques, for example, in Patent Document 1, carbon black and a specific hydrazide compound are blended into an elastomer containing natural rubber for the purpose of improving the chemical interaction between the rubber component and carbon black. A rubber composition is disclosed.

Japanese Patent Publication No. 4014-501827

However, the technology disclosed in Patent Document 1 is not sufficiently low in heat build-up in consideration of the demand for low fuel consumption, and further improvement has been desired. Further, in addition to the improvement of fuel efficiency, further improvements in wear resistance and crack resistance have been demanded.

In view of the above circumstances, an object of the present invention is to provide a tire excellent in wear resistance and crack resistance without impairing fuel efficiency, a rubber composition from which the tire is obtained, and a tire tread rubber composition. .

<1> A filler (A) containing carbon black (A1) having a cetyltrimethylammonium bromide specific surface area of 30 to 150 m ² /g and silica (A2) having a cetyltrimethylammonium bromide specific surface area of 210 m ² /g or more, and continuous A rubber component (B) comprising a diene polymer forming a phase and a diene polymer forming a discontinuous phase and having an affinity for the filler (A), and a fatty acid metal salt (C), The content of the filler (A) is 30 to 80 parts by mass with respect to 100 parts by mass of the rubber component (B), and the content (a1) of the carbon black (A1) and the silica (A2) The rubber composition has a ratio of (a1):(a2)=70-95:30-5 to the content (a2).

<2> The rubber composition according to <1>, wherein the content of the fatty acid metal salt (C) is 0.1 to 10 parts by mass with respect to 100 parts by mass of the rubber component (B).

<3> The rubber component (B) contains 50 to 95% by mass of a diene-based polymer that constitutes the continuous phase, and a diene-based polymer that constitutes the discontinuous phase and has an affinity with the filler (A) A diene polymer containing 5 to 50% by mass of a polymer, wherein the diene polymer constituting the continuous phase contains natural rubber, and the diene polymer constituting the discontinuous phase and having an affinity for the filler (A) is The rubber composition according to <1> or <2>, comprising a modified conjugated diene-based polymer having at least one functional group having affinity with the filler (A).

<4> The rubber composition according to any one of <1> to <3>, wherein the fatty acid content relative to 100 parts by mass of the rubber component (B) is 0 to 0.5 parts by mass.

<5> The rubber composition according to any one of <1> to <4>, wherein the carbon black (A1) has a hydrogen release rate higher than 0.3% by mass.

<6> Any one of <3> to <5>, wherein the functional group having an affinity for the filler (A) contains at least one selected from the group consisting of a nitrogen atom, an oxygen atom, and a silicon atom 1. The rubber composition according to 1.

<7> The rubber composition according to any one of <1> to <6>, wherein the diene polymer that constitutes the discontinuous phase and has an affinity for the filler (A) is a modified polybutadiene. .

<8> A rubber composition for a tire tread, comprising the rubber composition according to any one of <1> to <7>.

<9> A tire using the rubber composition according to any one of <1> to <7> for a tread.

ADVANTAGE OF THE INVENTION According to this invention, the rubber composition and tire tread rubber composition from which the tire which is excellent in abrasion resistance and crack resistance, and this tire are obtained can be provided, without impairing fuel efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS It is partial cross-sectional explanatory drawing of an example of the carbon black manufacturing furnace for manufacturing the carbon black which concerns on this invention.

<Rubber composition>
The rubber composition of the present invention is a filler containing carbon black (A1) having a cetyltrimethylammonium bromide specific surface area of 30 to 150 m ² /g and silica (A2) having a cetyltrimethylammonium bromide specific surface area of 210 m ² /g or more ( A), a rubber component (B) containing a diene polymer constituting a continuous phase and a diene polymer constituting a discontinuous phase and having an affinity for the filler (A), and a fatty acid metal salt (C) and the content of the filler (A) is 30 to 80 parts by mass with respect to 100 parts by mass of the rubber component (B), and the content (a1) of the carbon black (A1) and the The ratio of silica (A2) to content (a2) is (a1):(a2)=70-95:30-5.
Hereinafter, the cetyltrimethylammonium bromide specific surface area may be referred to as "CTAB specific surface area" or simply "CTAB".

Conventionally, when using a rubber component having a continuous phase and a discontinuous phase using two or more kinds of diene polymers that are incompatible with each other, the continuous phase ensures the crack resistance of the tire, and the discontinuous phase The wear resistance of the tire was given by including a filler in the. However, the conventional methods are insufficient in wear resistance, and in order to further improve the wear resistance, it has been necessary to increase the amount of uneven distribution of the filler in the discontinuous phase. However, for that purpose, it was necessary to increase the amount of the discontinuous phase, which resulted in a decrease in the amount of the continuous phase, resulting in a problem of impairing the crack resistance. In addition, simply increasing the amount of filler unevenly distributed in the discontinuous phase causes the filler to agglomerate and impairs low heat build-up, which tends to impair fuel efficiency.

On the other hand, in the rubber composition of the present invention, in the above configuration, by using a combination of specific amounts of carbon black and silica having different CTAB specific surface areas, small particles are formed in large particles. Particles of diameter can be placed. As a result, it is possible to suppress the aggregation of the filler, so it is possible to improve low heat build-up and fuel efficiency, and to increase the interaction between carbon black and silica, so that the tire wear resistance and It is thought that the crack resistance can be improved. In addition, since the uneven distribution of the filler in the discontinuous phase can be increased without reducing the amount of the continuous phase, the wear resistance and fuel efficiency of the tire can be improved. It is thought that it is difficult to impair the crack resistance of Furthermore, it is thought that the crack resistance of the tire can be improved by using a fatty acid metal salt instead of the fatty acid as the component that controls the vulcanization reaction of the rubber.
The details of the rubber composition and tire of the present invention are described below.

[Filler (A)]
The rubber composition of the present invention is a filler containing carbon black (A1) having a cetyltrimethylammonium bromide specific surface area of 30 to 150 m ² /g and silica (A2) having a cetyltrimethylammonium bromide specific surface area of 210 m ² /g or more ( A) is contained in an amount of 30 to 80 parts by mass per 100 parts by mass of the rubber component (B).
If the content of the filler (A) is less than 30 parts by mass with respect to 100 parts by mass of the rubber component (B), the wear resistance and crack resistance of the tire cannot be obtained, and if it exceeds 80 parts by mass, The rolling resistance of the tire increases, and the fuel efficiency is not excellent.
The content of the filler (A) is preferably 35 parts by mass or more, preferably 40 parts by mass or more, relative to 100 parts by mass of the rubber component (B), from the viewpoint of further improving the wear resistance of the tire. is more preferable, and 45 parts by mass or more is even more preferable. In addition, from the viewpoint of fuel efficiency of the tire, the content of the filler (A) is preferably 75 parts by mass or less, more preferably 70 parts by mass or less with respect to 100 parts by mass of the rubber component (B). More preferably, it is 65 parts by mass or less.

(Carbon black (A1))
The filler (A) contains carbon black (A1) having a cetyltrimethylammonium bromide specific surface area of 30 to 150 m ² /g.
If the CTAB specific surface area of the carbon black is less than 30 m ² /g, the wear resistance and crack resistance will not be excellent, and if it exceeds 150 m ² /g, the fuel efficiency will not be excellent. From the viewpoint of further improving wear resistance and crack resistance, the CTAB specific surface area of carbon black is preferably 50 m ² /g or more, more preferably 70 m ² /g or more. From the viewpoint of further improving fuel efficiency, the CTAB specific surface area of carbon black is preferably 140 m ² /g or less, more preferably 130 m ² /g or less.
The CTAB specific surface area of carbon black can be measured by a method conforming to JIS K 6217-3:2001 (Determination of specific surface area - CTAB adsorption method).

The type of carbon black is not particularly limited as long as the CTAB specific surface area falls within the above range, and examples thereof include GPF, FEF, HAF, ISAF, and SAF.

Carbon black (A1) preferably has a hydrogen release rate higher than 0.3% by mass.
When the carbon black (A1) has a hydrogen release rate higher than 0.3% by mass, it is possible to sufficiently ensure the polymer reinforcing property of the carbon black in the rubber composition, and the wear resistance and crack resistance of the tire. and excellent in fuel efficiency. Although there is no particular upper limit to the hydrogen release rate of carbon black (A1), the upper limit of the hydrogen release rate is usually about 0.60% by mass from the viewpoint of ease of production due to equipment limitations.
The hydrogen release rate of carbon black (A1) is as follows: (1) the carbon black sample is dried in a constant temperature dryer at 105 ° C. for 1 hour, cooled to room temperature (23 ° C.) in a desiccator, and (2) tin Approximately 10 mg was precisely weighed into a tube-shaped sample container, crimped and sealed, and (3) using a gas chromatograph, the amount of hydrogen gas generated was measured when heated at 2000 ° C. for 15 minutes under an argon stream. , expressed in percent by mass.

Although the method for producing carbon black (A1) having a hydrogen release rate higher than 0.3% by mass is not particularly limited, it can be obtained, for example, as follows.
Specifically, using a reactor (carbon black production furnace) in which a combustion gas generation zone, a reaction zone, and a reaction stop zone are connected, a high-temperature combustion gas is generated in the combustion gas generation zone, and then After the raw material is sprayed into the reaction zone to form a reaction gas stream containing carbon black, the reaction gas stream is quenched by the multi-stage quench medium introduction means in the reaction stop zone to terminate the reaction. good.
In the carbon black production furnace, the production air amount (kg/hr), air temperature (°C), fuel introduction amount (kg/hr), raw material introduction amount (kg/hr) and raw material preheating temperature (°C) are appropriately controlled. A carbon black with the desired hydrogen release rate is obtained.

FIG. 1 is a partial cross-sectional explanatory view of an example of a carbon black production furnace for producing carbon black according to the present invention, and is a reaction chamber into which a high-temperature gas containing a carbon black raw material (raw material hydrocarbon) is introduced. 10 and reaction continuation and cooling chamber 11 are shown. As shown in FIG. 1, the carbon black production furnace 1 is provided with a reaction continuation/cooling chamber 11 having a multi-stage rapid refrigerant introduction means 12 as a reaction stopping zone. A multi-stage quench medium introduction means 12 sprays a quench medium such as water onto the hot combustion gas stream from the reaction zone. Within the quench zone, the hot combustion gas stream is quenched by a quench medium to terminate the reaction.
Moreover, the carbon black production furnace 1 may further include a device for introducing a gas in the reaction zone or the reaction stop zone. Here, as the "gas body", air, mixtures of oxygen and hydrocarbons, combustion gases produced by combustion reactions thereof, and the like can be used.

Further, the nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 70 m ² /g or more. When the carbon black has an N ₂ SA of 70 m ² /g or more, the wear resistance and crack resistance of the tire can be further improved. Further, the N ₂ SA of carbon black is preferably 140 m ² /g or less. When it is 140 m ² /g or less, the dispersibility of carbon black in the rubber composition is excellent.
The N ₂ SA of carbon black can be obtained by Method A of JIS K 6217-2:2001 (Method for determining specific surface area—Nitrogen adsorption method—Single point method).

Dibutyl phthalate oil absorption (DBP oil absorption) is preferably 70 ml/100 g or more. When the carbon black has a DBP oil absorption of 70 ml/100 g or more, the wear resistance and crack resistance of the tire can be further improved. Moreover, from the viewpoint of the processability of the rubber composition, the DBP oil absorption of carbon black is preferably 180 ml/100 g or less.
Incidentally, the DBP oil absorption of carbon black can be determined according to JIS K 6217-4:2001 (Determination of oil absorption).

Carbon black (A1) and silica (A2) are such that the ratio of the content (a1) of carbon black (A1) to the content (a2) of silica (A2) is (a1):(a2) = 70 to 95. : Included in the rubber composition in the range of 30 to 5. This range is the ratio of silica (A2) in the total amount (a3) of the content (a1) of carbon black (A1) and the content (a2) of silica (A2) (hereinafter referred to as "silica ratio" (sometimes referred to as ) means 5 to 30% by mass.
If the silica ratio is less than 5% by mass, the crack resistance of the tire is not excellent, and if it exceeds 30% by mass, the fuel efficiency is not excellent. The silica ratio is preferably 10 to 25% by mass, more preferably 12 to 23% by mass.

The content (a1) of the carbon black (A1) can be freely used within the ranges described above for the content of the filler (A) in the rubber composition and the silica ratio. From the viewpoint of further enhancing the wear resistance, crack resistance and fuel economy of the rubber component (B), it is preferably 25 to 70 parts by mass, preferably 30 to 65 parts by mass. It is more preferably 32 to 60 parts by mass, even more preferably 35 to 55 parts by mass.

[Silica (A2)]
The rubber composition of the present invention contains silica (A2) having a cetyltrimethylammonium bromide specific surface area of 210 m ² /g or more.
When the CTAB specific surface area of silica (A2) is less than 210 m ² /g, the wear resistance and crack resistance of the tire are not excellent. The upper limit of the CTAB specific surface area of silica (A2) is not particularly limited, but at present, products exceeding 300 m ² /g cannot be obtained.
The CTAB specific surface area of silica (A2) is preferably 215 m ² /g or more, more preferably 220 m ² /g or more, from the viewpoint of further improving tire wear resistance and crack resistance.
The CTAB specific surface area of silica (A2) can be measured by a method conforming to the method of ASTM-D3765-80.

Silica (A2) is not particularly limited as long as it has a CTAB specific surface area of 210 m ² /g or more, and includes wet silica (hydrous silica), dry silica (anhydrous silica), colloidal silica, and the like.
Silica having a CTAB specific surface area of 210 m ² /g or more may be a commercially available product such as Zeosil Premium 200MP (trade name) manufactured by Rhodia.

The ratio of the CTAB specific surface area of carbon black (carbon black CTAB) to the CTAB specific surface area of silica (silica CTAB) is from the viewpoint of further improving tire wear resistance, crack resistance and fuel economy. CTAB/carbon black CTAB) is preferably from 1.7 to 3.5, more preferably from 2.0 to 3.0, and more preferably from 2.3 to 2.8.

The content (a2) of silica (A2) is as described above. and can be used freely.

[Silane coupling agent]
The rubber composition of the present invention contains a small amount of silica. It is desirable that the rubber composition of (1) further uses a silane coupling agent.
The content of the silane coupling agent in the rubber composition of the present invention is preferably 5 to 15% by mass or less relative to the content of silica. When the content of the silane coupling agent is 15% by mass or less relative to the content of silica, the effect of improving the reinforcing properties and dispersibility of the rubber component can be obtained, and economic efficiency is hardly impaired. Further, when the content of the silane coupling agent is 5% by mass or more relative to the content of silica, the dispersibility of silica in the rubber composition can be enhanced.

The silane coupling agent is not particularly limited, and bis(3-triethoxysilylpropyl) disulfide, bis(3-triethoxysilylpropyl) trisulfide, bis(3-triethoxysilylpropyl) tetrasulfide, bis (3-trimethoxysilylpropyl) disulfide, bis(3-trimethoxysilylpropyl) trisulfide, bis(3-trimethoxysilylpropyl) tetrasulfide, bis(2-triethoxysilylethyl) disulfide, bis(2-tri ethoxysilylethyl) trisulfide, bis(2-triethoxysilylethyl) tetrasulfide, 3-trimethoxysilylpropyl benzothiazole disulfide, 3-trimethoxysilylpropyl benzothiazole trisulfide, 3-trimethoxysilylpropyl benzothiazole tetrasulfide etc. are preferably exemplified.

The rubber composition of the present invention may contain fillers other than carbon black (A1) and silica (A2), and examples of such fillers include metal oxides such as alumina and titania.
The filler (A) preferably consists of carbon black (A1) and silica (A2), and the total amount (a3) of carbon black (A1) and silica (A2) is added to 100 parts by mass of the rubber component (B). It is preferably 30 to 80 parts by mass.

[Rubber component (B)]
The rubber composition of the present invention contains a rubber component (B) containing a diene polymer that constitutes a continuous phase and a diene polymer that constitutes a discontinuous phase and has an affinity for the filler (A).
Hereinafter, the diene-based polymer constituting the continuous phase may be referred to as a diene-based polymer (B1). Moreover, the diene-based polymer constituting the discontinuous phase may be referred to as a diene-based polymer (B2).
Hereinafter, when "diene-based polymer (B1)" and "diene-based polymer (B2)" are not distinguished and described simply as "diene-based polymer", the item to be described is the diene-based polymer ( This is a matter common to both B1) and the diene polymer (B2).

The diene polymer (B2) is a polymer having affinity with the filler (A). The diene-based polymer (B2) has an affinity for the filler (A), so that the filler can be unevenly distributed in the discontinuous phase.
The diene polymer includes at least one selected from the group consisting of natural rubber (NR) and synthetic diene rubber.
Specific examples of synthetic diene rubber include polyisoprene rubber (IR), polybutadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), butadiene-isoprene copolymer rubber (BIR), styrene-isoprene copolymer polymer rubber (SIR), styrene-butadiene-isoprene copolymer rubber (SBIR), and the like.
The continuous phase and the discontinuous phase may contain a single type of diene-based polymer, or may contain a blend of two or more types. Moreover, the continuous phase and the discontinuous phase may contain a non-diene polymer as long as the effects of the present invention are not impaired.

The rubber component (B) contains 50 to 95% by mass of the diene polymer (B1) constituting the continuous phase in order to maintain the state of phase separation between the continuous phase and the discontinuous phase, and the diene polymer constituting the discontinuous phase It preferably contains 5 to 50% by mass of the polymer (B2).
From the viewpoint of improving tire crack resistance, wear resistance and fuel efficiency, the content (b1) of the diene polymer (B1) in the rubber component (B) is 51 to 90% by mass. More preferably, 55 to 85% by mass is even more preferable. From the same point of view, the content (b2) of the diene polymer (B1) in the rubber component (B) is more preferably 10 to 49% by mass, even more preferably 15 to 45% by mass. .

The continuous phase may contain either one of the natural rubber and the synthetic diene rubber, or may contain both of them. is preferred. Specifically, the content of natural rubber in the continuous phase is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 90% by mass or more, and 100% by mass. may be

The diene-based polymer (B2) constituting the discontinuous phase (a diene-based polymer having an affinity for the filler (A)) is polybutadiene (BR), styrene-butadiene copolymer (SBR), butadiene-isoprene copolymer. Polymer (BIR), butadiene-based polymers such as styrene-butadiene-isoprene copolymer (SBIR). The butadiene-based polymer may be modified or unmodified.
Among the above, polybutadiene rubber (BR) is preferable as the diene polymer (B2).
The discontinuous phase may consist only of the modified butadiene polymer or the unmodified butadiene polymer, or may further contain other diene polymers. From the viewpoint of improving the crack resistance of the tire, the content of the modified butadiene-based polymer or the unmodified butadiene-based polymer in the discontinuous phase is preferably 50% by mass or more, and is 70% by mass or more. is more preferable, more preferably 90% by mass or more, and may be 100% by mass.

The diene-based polymer (B2) is a modified conjugated diene-based polymer having at least one functional group having an affinity for the filler (A) from the viewpoint of improving wear resistance and fuel efficiency of the tire. Preferably.
The modified butadiene-based polymer described above is preferably a butadiene-based polymer having at least one functional group having an affinity for the filler (A), and the functional group having an affinity for the filler (A) is preferably Modified polybutadiene having one or more is preferred.

Functional groups having an affinity for the filler (A) include functional groups having one or more atoms selected from nitrogen atoms, oxygen atoms, sulfur atoms, metalloid atoms and metal atoms.
The metalloid atom is preferably one or more atoms selected from boron, silicon, germanium, arsenic, antimony and tellurium, more preferably one or more atoms selected from boron, silicon and germanium, and particularly preferably silicon.
The metal atom is preferably one or more atoms selected from tin, titanium, zirconium, bismuth and aluminum, more preferably one or more atoms selected from tin and titanium, and particularly preferably tin.
The functional group having an affinity for the filler (A) preferably contains at least one selected from the group consisting of nitrogen atoms, oxygen atoms and silicon atoms.

The functional group having at least one atom selected from nitrogen, oxygen, sulfur, semimetal and metal atoms is at least one selected from nitrogen, oxygen, sulfur, metalloid and metal atoms. is a residue of a compound having an atom of (hereinafter sometimes referred to as a "heteroatom-containing compound").
The heteroatom-containing compound may react with the active terminal of the conjugated diene-based polymer as a modifier to form a modified conjugated diene-based polymer, or the nitrogen-containing compound as the heteroatom-containing compound may react with the alkali metal. Then, a polymerization initiator for anionic polymerization may be formed to form a modified conjugated diene-based polymer having a nitrogen-containing compound residue at the initiation end of the conjugated diene-based polymer.
As the modifier that reacts with the active terminal of the conjugated diene-based polymer, one or more selected from the following tin compounds, nitrogen- and silicon-containing compounds, oxygen- and silicon-containing compounds, sulfur- and silicon-containing compounds, and nitrogen-containing compounds A denaturant is mentioned.

As the tin compound, one or more tin compounds selected from tin tetrachloride and tributyltin chloride are preferably exemplified. Nitrogen- and silicon-containing compounds include N,N-bis(trimethylsilyl)aminopropylmethyldimethoxysilane, 1-trimethylsilyl-2,2-dimethoxy-1-aza-2-silacyclopentane, N,N-bis(trimethylsilyl) aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N , N-bis(trimethylsilyl)aminoethyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethylmethyldimethoxysilane and N,N-bis(trimethylsilyl)aminoethylmethyldiethoxysilane. Silane compounds having an amino group are preferably exemplified, N-methyl-N-trimethylsilylaminopropyl(methyl)dimethoxysilane, N-methyl-N-trimethylsilylaminopropyl(methyl)diethoxysilane, N-trimethylsilyl(hexamethyleneimine -2-yl)propyl(methyl)dimethoxysilane, N-trimethylsilyl(hexamethyleneimin-2-yl)propyl(methyl)diethoxysilane, N-trimethylsilyl(pyrrolidin-2-yl)propyl(methyl)dimethoxysilane, N -trimethylsilyl(pyrrolidin-2-yl)propyl(methyl)diethoxysilane, N-trimethylsilyl(piperidin-2-yl)propyl(methyl)dimethoxysilane, N-trimethylsilyl(piperidin-2-yl)propyl(methyl)diethoxysilane Silane, N-trimethylsilyl(imidazol-2-yl)propyl(methyl)dimethoxysilane, N-trimethylsilyl(imidazol-2-yl)propyl(methyl)diethoxysilane, N-trimethylsilyl(4,5-dihydroimidazole-5- Silane compounds having a protected secondary amino group selected from yl)propyl(methyl)dimethoxysilane and N-trimethylsilyl(4,5-dihydroimidazol-5-yl)propyl(methyl)diethoxysilane are preferably exemplified. be done.

Further, the oxygen- and silicon-containing compounds include 2-glycidoxyethyltrimethoxysilane, 2-glycidoxyethyltriethoxysilane, (2-glycidoxyethyl)methyldimethoxysilane, and 3-glycidoxypropyltrimethoxysilane. Silane, 3-glycidoxypropyltriethoxysilane, (3-glycidoxypropyl)methyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl Epoxy group-containing hydrocarbyloxysilane compounds selected from one or more of triethoxysilane and 2-(3,4-epoxycyclohexyl)ethyl(methyl)dimethoxysilane are preferably exemplified. Preferred examples include hydrocarbyloxysilane compounds containing thioepoxy groups, in which the epoxy groups of the hydrocarbyloxysilane compounds are substituted with thioepoxy groups. Preferred examples of nitrogen-containing compounds include compounds selected from one or more of bis(diethylamino)benzophenone, dimethylimidazolidinone, N-methylpyrrolidone and 4-dimethylaminobenzylideneaniline.

The conjugated diene-based polymer before modification that forms the modified conjugated diene-based polymer may be a conjugated diene-based homopolymer obtained by polymerizing one type of conjugated diene-based monomer, or may be a conjugated diene-based homopolymer obtained by polymerizing two or more types of monomers. A conjugated diene-based copolymer formed by The conjugated diene-based copolymer may be obtained by polymerizing two or more conjugated diene-based monomers, or one or more conjugated diene-based monomers and one or more aromatic vinyl compounds. It may be obtained by copolymerization.
Conjugated diene-based monomers include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-phenyl-1,3-butadiene, and 1,3-hexadiene. etc. Among these, 1,3-butadiene, isoprene and 2,3-dimethyl-1,3-butadiene are particularly preferred.
Examples of aromatic vinyl compounds include styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, 4-cyclohexylstyrene and 2,4,6-trimethylstyrene. . Among these, a styrene group is particularly preferred.

Examples of the conjugated diene-based polymer before modification that forms the modified conjugated diene-based polymer include polybutadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), polyisoprene rubber (IR), and isoprene-butadiene copolymer. Rubber (IBR), styrene-isoprene copolymer rubber (SIR) and the like are preferable, but from the viewpoint of improving tire tread performance, polybutadiene rubber and polyisoprene rubber are more preferable, and polybutadiene rubber is particularly preferable.

The method of polymerizing the conjugated diene polymer may be anion polymerization or coordination polymerization.
When the conjugated diene-based polymer is obtained by anionic polymerization, an alkali metal compound is used as the polymerization initiator, and a lithium compound is preferred.
The lithium compound of the polymerization initiator is not particularly limited, but hydrocarbyllithium and lithium amide compounds are preferably used. When the former hydrocarbyllithium is used, it has a hydrocarbyl group at the polymerization initiation terminal and the other is a polymerization active site, a conjugated diene polymer is obtained. Further, when the latter lithium amide compound is used, a conjugated diene polymer having a nitrogen-containing group at the polymerization initiation terminal and a polymerization active site at the other terminal is obtained.

The above hydrocarbyllithium preferably has a hydrocarbyl group having 2 to 20 carbon atoms, such as ethyllithium, n-propyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, tert-octyllithium, n-decyl. Lithium, phenyllithium, 2-naphthyllithium, 2-butyl-phenyllithium, 4-phenyl-butyllithium, cyclohexyllithium, cyclopentyllithium, reaction products of diisopropenylbenzene and butyllithium, and the like. However, among these, n-butyllithium is particularly preferred.

Examples of lithium amide compounds include lithium hexamethyleneimide, lithium pyrrolidide, lithium piperidide, lithium heptamethyleneimide, lithium dodecamethyleneimide, lithium dimethylamide, lithium diethylamide, lithium dibutylamide, lithium dipropylamide, lithium diheptylamide, lithium dihexylamide, lithium dioctylamide, lithium di-2-ethylhexylamide, lithium didecylamide, lithium-N-methylpiverazide, lithium ethylpropylamide, lithium ethylbutylamide, lithium ethylbenzylamide, lithium methylphenethylamide etc. Among these, cyclic lithium amides such as lithium hexamethyleneimide, lithium pyrrolidide, lithium piperidide, lithium heptamethyleneimide, and lithium dodecamethyleneimide are preferred from the viewpoint of interaction effect with carbon black and polymerization initiation ability. , lithium hexamethyleneimide and lithium pyrrolidide are more preferred.

When lithium hexamethyleneimide is used as a polymerization initiator, modified conjugation having a hexamethyleneimino group, which is a nitrogen-containing compound residue, as a functional group having an atom other than carbon and hydrogen at the starting end of the conjugated diene polymer It is more preferable because a diene-based polymer can be obtained.
Having a nitrogen-containing compound residue at the starting end of the conjugated diene-based polymer, and having at the active end of the conjugated diene-based polymer a tin compound residue, a nitrogen- and silicon-containing compound residue, an oxygen- and silicon-containing compound residue, and sulfur And the modified conjugated diene-based polymer having one or more compound residues selected from silicon-containing compound residues and nitrogen-containing compound residues further reduces rolling resistance, has excellent fuel efficiency, wear resistance and resistance It is more preferable from the viewpoint of further improving the crack resistance.

A method for producing a conjugated diene-based polymer by anionic polymerization using a lithium compound as a polymerization initiator is not particularly limited, and conventionally known methods can be used.
Specifically, a conjugated diene compound or a conjugated diene compound and an aromatic vinyl compound are reacted in an organic solvent inert to the reaction, for example, a hydrocarbon solvent such as an aliphatic, alicyclic or aromatic hydrocarbon compound. An intended conjugated diene polymer can be obtained by anionic polymerization using a lithium compound as a polymerization initiator, optionally in the presence of a randomizer.
The hydrocarbon solvent preferably has 3 to 8 carbon atoms, such as propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, propene, 1-butene, isobutene, trans-2- butene, cis-2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, benzene, toluene, xylene, ethylbenzene and the like. These may be used alone or in combination of two or more.

In addition, the optional randomizer is used to control the microstructure of the conjugated diene polymer, such as increasing 1,2 bonds in butadiene moieties in butadiene-styrene copolymers, increasing 3,4 bonds in isoprene polymers, or It is a compound that has the effect of controlling the composition distribution of monomer units in a conjugated diene compound-aromatic vinyl compound copolymer, such as randomizing butadiene units and styrene units in a butadiene-styrene copolymer. The randomizer is not particularly limited, and any known compound generally used as a conventional randomizer can be appropriately selected and used. Specifically, dimethoxybenzene, tetrahydrofuran, dimethoxyethane, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, 2,2-bis(2-tetrahydrofuryl)-propane, triethylamine, pyridine, N-methylmorpholine, N,N,N', Ethers such as N'-tetramethylethylenediamine and 1,2-dipiperidinoethane, and tertiary amines can be mentioned. Potassium salts such as potassium-tert-amylate and potassium-tert-butoxide, and sodium salts such as sodium-tert-amylate can also be used.
These randomizers may be used singly or in combination of two or more. Also, the amount used is preferably selected in the range of 0.01 to 1000 molar equivalents per 1 mol of the lithium compound.

The temperature in this polymerization reaction is preferably selected in the range of 0 to 150°C, more preferably 20 to 130°C. Although the polymerization reaction can be conducted under generated pressure, it is usually desirable to operate at pressures sufficient to maintain the monomers substantially in the liquid phase. That is, the pressure will depend on the particular materials being polymerized, the polymerization medium used, the polymerization temperature, etc., but higher pressures can be used if desired, such pressures being inert gases with respect to the polymerization reaction. can be obtained by an appropriate method such as pressurization.

On the other hand, when the modified conjugated diene-based polymer is produced by coordination polymerization using a rare earth metal compound as a polymerization initiator, the following components (D), (E), and (F) are further used in combination. preferable.
The component (D) used in the coordination polymerization is selected from rare earth metal compounds, complex compounds of rare earth metal compounds and Lewis bases, and the like. Examples of rare earth metal compounds include carboxylates of rare earth elements, alkoxides, β-diketone complexes, phosphates and phosphites. Examples of Lewis bases include acetylacetone, tetrahydrofuran, pyridine, N, N -Dimethylformamide, thiophene, diphenyl ether, triethylamine, organic phosphorus compounds, monohydric or dihydric alcohols, and the like. Lanthanum, neodymium, praseodymium, samarium, and gadolinium are preferable as the rare earth element of the rare earth metal compound, and among these, neodymium is particularly preferable. Specific examples of component (D) include neodymium tri-2-ethylhexanoate, a complex compound of neodymium tri-2-ethylhexanoate and acetylacetone, neodymium tri-neodecanoate, a complex compound of neodymium tri-2-ethylhexanoate and acetylacetone, and neodymium tri-n-butoxide. be done. These (D) components may be used individually by 1 type, or may be used in mixture of 2 or more types.

The (E) component used for coordination polymerization is selected from organoaluminum compounds. Specific examples of the organoaluminum compound include a trihydrocarbylaluminum compound represented by the formula: R ¹² ₃ Al, and a hydrocarbylaluminum hydride represented by the formula: R ¹² ₂ AlH or R ¹² AlH ₂ (wherein R ¹² are each independently a hydrocarbon group having 1 to 30 carbon atoms), hydrocarbyl aluminoxane compounds having a hydrocarbon group having 1 to 30 carbon atoms, and the like. Specific examples of the organoaluminum compounds include trialkylaluminums, dialkylaluminum hydrides, alkylaluminum dihydrides, and alkylaluminoxanes. These compounds may be used singly or in combination of two or more. As component (E), it is preferable to use an aluminoxane together with another organoaluminum compound.

The (F) component used in coordination polymerization is a compound having a hydrolyzable halogen or a complex compound of these with a Lewis base; an organic halide having a tertiary alkyl halide, benzyl halide or allyl halide; a non-coordinating anion and It is selected from ionic compounds consisting of counter cations and the like. Specific examples of such component (F) include alkylaluminum dichlorides, dialkylaluminum chlorides, silicon tetrachloride, tin tetrachloride, complexes of zinc chloride and Lewis bases such as alcohols, and Lewis bases such as magnesium chloride and alcohols. Complexes with bases, benzyl chloride, t-butyl chloride, benzyl bromide, t-butyl bromide, triphenylcarboniumtetrakis(pentafluorophenyl)borate and the like. These (F) components may be used individually by 1 type, or may be used in mixture of 2 or more types.

In addition to the above components (D), (E), and (F), the polymerization initiator is, if necessary, the same conjugated diene compound and/or non-conjugated diene compound as the monomer for polymerization. may be prepared. In addition, part or all of component (D) or component (F) may be supported on an inert solid. The amount of each component mentioned above can be set as appropriate, but component (A) is usually 0.001 to 0.5 millimoles (mmol) per 100 g of the monomer. The molar ratio of component (E)/component (D) is preferably 5 to 1,000, and component (F)/component (D) is preferably 0.5 to 10.

The polymerization temperature in the coordination polymerization is preferably in the range of -80 to 150°C, more preferably in the range of -20 to 120°C. In addition, as the solvent used for coordination polymerization, a hydrocarbon solvent inert to the reaction exemplified in the above-mentioned anionic polymerization can be used, and the concentration of the monomer in the reaction solution is the same as in the case of anionic polymerization. . Furthermore, the reaction pressure in coordination polymerization is the same as in the case of anionic polymerization, and the raw materials used in the reaction are desirably those from which reaction inhibitors such as water, oxygen, carbon dioxide and protic compounds have been substantially removed.
As the modified conjugated diene-based polymer, one obtained by anionic polymerization using an organic alkali metal compound, particularly alkyllithium, is preferable.

In both cases of anionic polymerization and coordination polymerization, the conjugated diene polymer can be obtained by subjecting the polymerization active terminal and the above modifier to a modification reaction after the polymerization reaction to obtain a modified conjugated diene polymer.
The modification reaction is preferably carried out at a temperature of 20°C or higher, but the polymerization temperature of the conjugated diene polymer can be used as it is, and a more preferable range is 30 to 120°C. When the reaction temperature is lowered, the viscosity of the polymer tends to increase too much and the dispersibility of the reactant tends to deteriorate. On the other hand, when the reaction temperature is high, the polymerization active site tends to be easily deactivated.
The amount of modifier used is preferably in the range of 0.25 to 3.0 mol, more preferably in the range of 0.5 to 1.5 mol, per 1 mol of the polymerization initiator used in the production of the conjugated diene polymer. .

[Fatty acid metal salt (C)]
The rubber composition of the present invention contains a fatty acid metal salt (C).
As the fatty acid metal salt (C), a saturated fatty acid metal salt, an unsaturated fatty acid metal salt, or a mixture thereof can be used.
Specifically, fatty acid metal salts (C) include palmitic acid, stearic acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, arachidic acid, behenic acid, cerotic acid, montanic acid, melisic acid, and the like. Saturated fatty acid metal salts of zomaric acid, petroselinic acid, oleic acid, erucic acid, cetacean acid, linoleic acid, eleostearic acid, moroctic acid, valinaric acid, sardine acid, hiragashira acid, nisic acid, ricinoleic acid, lauroleic acid , elaidic acid, erucic acid, linoleidic acid, linolenic acid, arachidonic acid, and other unsaturated fatty acid metal salts.
As the metal element forming a metal salt with the saturated fatty acid or unsaturated fatty acid described above, at least selected from the group consisting of K, Ca, Na, Mg, Zn, Co, Ni, Ba, Fe, Al, Cu and Mn At least one metal element selected from the group consisting of Zn, K, and Ca is preferred, and Zn (zinc) is more preferred. Therefore, the fatty acid metal salt is particularly preferably fatty acid zinc.

Preferred fatty acid metal salts (C) include metal salts of mono-fatty acids having 8 to 18 carbon atoms, specifically zinc caprylate, zinc pelargonate, zinc caprate, zinc laurate, zinc myristate, palmitate. Preferred examples include zinc acid, zinc stearate, zinc oleate and zinc linoleate. Among these, zinc stearate, zinc oleate, and zinc palmitate are preferably exemplified.

As the fatty acid metal salt (C), commercially available products may be used. Specifically, Aktiplast series (manufactured by Rhein Chemie, specifically Aktiplast PP (main components are zinc oleate and palmitic acid zinc)), ULTRALFOW series (manufactured by Performance Additives), STRUKTOL A50P (manufactured by Structol), Exton L-2-G (manufactured by Kawaguchi Chemical Industry Co., Ltd.), and the like.

Fatty acid metal (C) salts may be used singly or in combination of two or more.
From the viewpoint of suppressing deterioration of wear resistance and crack resistance, the content of the fatty acid metal salt (C) is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the rubber component (B). , more preferably 0.5 to 7 parts by mass, and even more preferably 1 to 5 parts by mass.

〔fatty acid〕
The rubber composition of the present invention preferably does not contain fatty acids, and preferably contains 0.5 parts by mass or less of fatty acids with respect to 100 parts by mass of the rubber component (B). Specifically, the content of the fatty acid is preferably 0 to 0.5 parts by mass with respect to 100 parts by mass of the rubber component (B).
When the content of the fatty acid is 0.5 parts by mass or less relative to 100 parts by mass of the rubber component (B), it is possible to suppress deterioration in tire crack resistance.
The content of the fatty acid relative to 100 parts by mass of the rubber component (B) is more preferably 0 to 0.3 parts by mass, and even more preferably 0 part by mass.

(Various components)
The rubber composition of the present invention includes, in addition to the rubber component (B), carbon black (A1) and silica (A2) described above, and an optionally contained silane coupling agent, for example, a vulcanizing agent and a vulcanizing agent. Various components commonly used in the rubber industry, such as a sulfur accelerator, zinc oxide, stearic acid, anti-aging agents, etc., can be appropriately selected and blended within a range that does not impair the object of the present invention. Commercially available products can be suitably used as these various components. The rubber composition is prepared by blending the rubber component, carbon black (A1), silica (A2), and various other appropriately selected components, and using a closed mixer such as a Banbury mixer, an internal mixer, or an intensive mixer. After kneading using a non-sealed kneading device such as a kneading device, rolls, etc., it can be prepared by heating and extruding.

<Rubber composition for tire tread>
The tire tread rubber composition of the present invention contains the rubber composition of the present invention.
INDUSTRIAL APPLICABILITY The rubber composition of the present invention can be used in the production of various rubber products such as tires, antivibration rubbers, seismic isolation rubbers, belts such as conveyor belts, rubber crawlers, and various hoses.
Since the tire manufactured using the rubber composition of the present invention for the tread is excellent in wear resistance and crack resistance without impairing fuel efficiency, the rubber composition of the present invention is a rubber composition for tire treads. Suitable for

<Tire>
The vulcanized rubber obtained by vulcanizing the rubber composition of the present invention can be used for various rubber products such as tires, anti-vibration rubber, seismic isolation rubber, belts such as conveyor belts, rubber crawlers, and various hoses. .
Among them, it is preferable to use the rubber composition of the present invention in a tire having a tread, and the tire has excellent wear resistance and crack resistance without impairing fuel efficiency.

The application site of the rubber composition of the present invention in the tire is not particularly limited and can be appropriately selected according to the purpose. is mentioned.
A conventional method can be used as a method for manufacturing a tire. For example, a carcass layer, a belt layer, a tread layer and the like comprising the rubber composition of the present invention and cords are laminated on a tire molding drum, and the drum is removed to form a green tire. Then, the green tire is heated and vulcanized according to a conventional method to produce a desired tire (for example, a pneumatic tire).

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

<Preparation of rubber composition, production and evaluation of vulcanized rubber>
[Examples 1 to 5, Examples 7 to 9, Comparative Example 1, Comparative Example 3, and Comparative Examples 5 to 7]
Rubber compositions having formulations shown in Tables 1, 4 and 5 were prepared according to a conventional method.
The prepared rubber composition was vulcanized to produce a vulcanized rubber, and a test piece cut from the vulcanized rubber was used to evaluate fuel efficiency, wear resistance and crack resistance of the tire. The results are shown in Tables 4-5.

[Example 6, Comparative Example 2, Comparative Example 4, and Comparative Example 8]
Rubber compositions having formulations shown in Tables 1, 4 and 5 were prepared according to a conventional method.
The prepared rubber composition is vulcanized to produce a vulcanized rubber, and a test piece cut from the vulcanized rubber is used to evaluate the fuel economy, wear resistance and crack resistance of the tire. The results are shown in Tables 4-5.

(1) Low fuel consumption [Examples 1 to 5, Examples 7 to 9, Comparative Examples 1, 3, and 5 to 7]
A plate-shaped test piece having a thickness of 2 mm was cut out from the vulcanized rubber. Using a spectrometer (dynamic viscoelasticity measuring tester) manufactured by Ueshima Seisakusho Co., Ltd., at a frequency of 52 Hz, an initial strain of 10%, a measurement temperature of 60 ° C., and a dynamic strain of 1%, the loss tangent (tan δ) of the test piece is obtained and compared. The value of Example 1 is indexed as 100. The smaller the index value, the lower the loss tangent (tan δ), which means excellent low heat build-up. This means that the trial tire composed of the vulcanized rubber of the test piece has a low rolling resistance, indicating that the trial tire is excellent in fuel efficiency.

[Example 6, Comparative Example 2, Comparative Example 4, and Comparative Example 8]
A plate-shaped test piece having a thickness of 2 mm is cut out from the vulcanized rubber. Using a spectrometer (dynamic viscoelasticity measuring tester) manufactured by Ueshima Seisakusho Co., Ltd., at a frequency of 52 Hz, an initial strain of 10%, a measurement temperature of 60 ° C., and a dynamic strain of 1%, the loss tangent (tan δ) of the test piece is obtained and compared. The value of Example 1 is indexed as 100. The smaller the index value, the lower the loss tangent (tan δ), which means excellent low heat build-up. This means that the trial tire composed of the vulcanized rubber of the test piece has a low rolling resistance, indicating that the trial tire is excellent in fuel efficiency.

(2) Abrasion resistance [Examples 1 to 5, Examples 7 to 9, Comparative Example 1, Comparative Example 3, and Comparative Examples 5 to 7]
A plate-shaped rubber plate having a thickness of 2 mm was cut out from the vulcanized rubber. A test piece was prepared from the cut rubber plate and evaluated for wear resistance.
Abrasion resistance was determined by a Lambourn abrasion test conforming to JIS K 6264-1993, where the amount of abrasion of test pieces was tested at 220° C. to determine the amount of abrasion of the test pieces of Examples and Comparative Examples. Taking Comparative Example 1 as 100, the index was calculated from the wear amount of the test pieces of Examples and Comparative Examples by the following formula.
Abrasion resistance index = (Abrasion amount of Comparative Example 1/Abrasion amount of each test piece) x 100
The larger the wear resistance index, the better the wear resistance of the test piece, and the better the wear resistance of the prototype tire made of the vulcanized rubber of the test piece. Note that "tested at 220°C" means that the test was performed under the following conditions where the maximum surface temperature of the test piece was 220±10°C. The test conditions are as follows.
Test piece dimensions: diameter x thickness = 49.0 mm x 5.0 mm
Specimen rotation speed: 200 rpm
Test road surface rotation speed: 20 rpm
Test load: 7kgf
Test time: 16 seconds Ambient temperature: 25°C

[Example 6, Comparative Example 2, Comparative Example 4, and Comparative Example 8]
A plate-shaped rubber plate having a thickness of 2 mm is cut out from the vulcanized rubber. A test piece is prepared from the cut rubber plate and evaluated for wear resistance.
Abrasion resistance is determined by the Lambourn abrasion test conforming to JIS K 6264-1993, testing the abrasion loss of the test piece at 220° C., and determining the abrasion loss of the test pieces of Examples and Comparative Examples. Assuming that Comparative Example 1 is 100, the index is calculated from the wear amounts of the test pieces of Examples and Comparative Examples according to the following formula.
Abrasion resistance index = (Abrasion amount of Comparative Example 1/Abrasion amount of each test piece) x 100
The larger the wear resistance index, the better the wear resistance of the test piece, and the better the wear resistance of the prototype tire made of the vulcanized rubber of the test piece. Note that "testing at 220°C" means testing under the following conditions where the maximum surface temperature of the test piece is 220±10°C. The test conditions are as follows.
Test piece dimensions: diameter x thickness = 49.0 mm x 5.0 mm
Specimen rotation speed: 200 rpm
Test road surface rotation speed: 20 rpm
Test load: 7kgf
Test time: 16 seconds Ambient temperature: 25°C

(3) Crack resistance [Examples 1 to 5, Examples 7 to 9, Comparative Example 1, Comparative Example 3, and Comparative Examples 5 to 7]
A plate-like sheet having a thickness of 2 mm was cut out from the vulcanized rubber. A JIS No. 5 test piece was prepared from the cut rubber sheet, and a crack of 0.5 mm was made in the center of the test piece.
Both ends of the test piece were gripped, input was repeatedly performed under the following conditions, and the number of times until the test piece broke was measured. The crack resistance was calculated from the following formula and expressed as an index with Comparative Example 1 being 100.
Crack resistance index = (number of times of breakage of each test piece/number of breakages of Comparative Example 1) x 100
The larger the crack resistance index, the more excellent the crack resistance of the test piece, and the more excellent the crack resistance of the prototype tire composed of the vulcanized rubber of the test piece.
Gauge distance: 30.0 mm
Test stress: 1.5N (maximum), 0N (minimum)
Frequency: 5Hz
Ambient temperature: 80°C

[Example 6, Comparative Example 2, Comparative Example 4, and Comparative Example 8]
A plate-like sheet having a thickness of 2 mm is cut out from the vulcanized rubber. A JIS No. 5 test piece is prepared from the cut rubber sheet, and a crack of 0.5 mm is made in the center of the test piece.
Both ends of the test piece are gripped, input is repeatedly performed under the following conditions, and the number of times until the test piece breaks is measured. The crack resistance is calculated from the following formula and indicated as an index with Comparative Example 1 being 100.
Crack resistance index = (number of times of breakage of each test piece/number of breakages of Comparative Example 1) x 100
The larger the crack resistance index, the more excellent the crack resistance of the test piece, and the more excellent the crack resistance of the prototype tire composed of the vulcanized rubber of the test piece.
Gauge distance: 30.0 mm
Test stress: 1.5N (maximum), 0N (minimum)
Frequency: 5Hz
Ambient temperature: 80°C

[Details of each component in Table 1]
Details of each component other than the rubber component, filler and fatty acid metal salt in Table 1 are as follows.
(1) Silane coupling agent: Shin-Etsu Chemical Co., Ltd., ABC-856
(2) Fatty acid: trade name “Stearic acid 50S” manufactured by New Japan Chemical Co., Ltd.
(3) Sulfur: manufactured by Tsurumi Chemical Co., Ltd., trade name “powder sulfur”
(4) Vulcanization accelerator: N-cyclohexyl-2-benzothiazolylsulfenamide, manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., trade name "Noccellar CZ-G"
(5) Zinc white: manufactured by Hakusui Tech Co., Ltd., trade name “No. 3 zinc white”
(6) Anti-aging agent: N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name "Nocrac 6C"

[Details of each component in Tables 4 and 5]
Details of each component shown in Tables 4 and 5 are as follows.
(1) NR: natural rubber, RSS#1
(2) Modified BR: Modified polybutadiene rubber produced according to the following production example

(3) CB-1: Asahi Carbon Co., Ltd., trade name "Asahi #70" (CTAB: 83 m ² /g, DBP oil absorption: 77 ml/100 g, N ₂ SA: 101 m ² /g, hydrogen release rate: 0. 3% by mass or less)
(4) CB-2: Asahi Carbon Co., Ltd., trade name "Asahi #80" (CTAB: 100 m ² /g, DBP oil absorption: 115 ml/100 g, N ₂ SA: 113 m ² /g, hydrogen release rate: 0. 3% by mass or less)
(5) CB-3: High-hydrogen carbon black produced according to the following production example (CTAB: 125 m ² /g, DBP oil absorption: 170, hydrogen release rate: 0.35% by mass)

(6) Silica-1: manufactured by Evonik, trade name “9500GR” (CTAB: 220m ² /g)
(7) Silica-2: Rohdia, trade name “zeosil Premium 200MP” (CTAB: 200 m ² /g)
(8) Silica-3: silica having a CTAB specific surface area of 230 m ² /g produced by the following production method (9) Fatty acid metal salt 1: manufactured by Rhein Chemie, trade name “Aktiplast PP” (main components are zinc oleate and zinc palmitate)
(10) Fatty acid metal salt 2: manufactured by Performance Additives, trade name "ULTRA-FLOW 500"

[Production example of modified polybutadiene rubber (modified BR)]
283 g of cyclohexane, 50 g of 1,3-butadiene, 0.0057 mmol of 2,2-ditetrahydrofurylpropane, and 0.513 mmol of hexamethyleneimine are added to a dried, nitrogen-purged, pressure-resistant glass container of about 900 mL, and further n-butyl. After adding 0.57 mmol of lithium (BuLi), polymerization was carried out for 4.5 hours in a 50° C. warm water bath equipped with a stirrer. The polymerization conversion rate at this time was approximately 100%. Next, 0.100 mmol of tin tetrachloride as a modifier (coupling agent) was quickly added to this polymerization reaction system, and the mixture was further stirred at 50° C. for 30 minutes for modification reaction. Thereafter, 0.5 mL of an isopropanol solution of 2,6-di-t-butyl-p-cresol (BHT) (BHT concentration: 5% by mass) is added to the polymerization reaction system to stop the reaction, and further according to a conventional method. After drying, a modified polybutadiene rubber (modified BR) was obtained. The resulting modified BR had a vinyl bond content in the butadiene moiety of 14%, a glass transition temperature (Tg) of -95°C, and a coupling efficiency of 65%.
Regarding the obtained modified BR, the amount of vinyl bonds in the butadiene portion was determined from the integration ratio of the 1H-NMR spectrum, and the peak area on the highest molecular weight side with respect to the entire area of the molecular weight distribution curve by gel permeation chromatography (GPC). The coupling rate was determined from the ratio, and the glass transition temperature was determined from the inflection point of the DSC curve.

[Production example of high-hydrogen carbon black (manufacturing method of carbon black CB-3)]
Carbon black CB-3 was produced based on the method shown in JP-A-2015-131926. Specifically, using the carbon black production furnace shown in FIG. 1, carbon black CB-3 was produced. However, in FIG. 1, as the multi-stage rapid refrigerant introduction means 12, there are three stages consisting of the first rapid refrigerant introduction means 12-X, the second rapid refrigerant introduction means 12-Y, and the final rapid refrigerant introduction means 12-Z. A quench medium introduction means was used.
In addition, in order to monitor the temperature inside the manufacturing furnace, the above-described manufacturing furnace having a structure in which thermocouples can be inserted into the furnace at any number of positions was used. In the carbon black production furnace, heavy oil A having a specific gravity of 0.8622 (15° C./4° C.) was used as the fuel, and heavy oil having the properties shown in Table 2 below was used as the raw material oil. The operating conditions of the carbon black production furnace and the properties of carbon black CB-3 are shown in Table 3 below.

[Method for producing silica-3]
12 L of a sodium silicate solution (SiO ₂ /Na ₂ O mass ratio of 3.5) with a concentration of 10 g/L were introduced into a 25 L stainless steel reactor. The solution was heated to 80°C. All reactions were carried out at this temperature. Sulfuric acid having a concentration of 80 g/L was introduced with stirring (300 rpm, propeller stirrer) until the pH reached a value of 8.9.

A sodium silicate solution having a concentration of 230 g/L (having a SiO ₂ /Na ₂ O mass ratio of 3.5) was added at a rate of 76 g/min and sulfuric acid having a concentration of 80 g/L was added to bring the pH of the reaction mixture to 8. Simultaneously introduced into the reactor over 15 minutes at a rate set to maintain a value of 0.9. A sol of barely aggregated particles was thus obtained. The sol was collected and rapidly cooled using a copper coil with circulating cold water. The reactor was quickly cleaned.

4 L of pure water was introduced into this 25 L reactor. Sulfuric acid having a concentration of 80 g/L was introduced until a pH of 4 was reached. Simultaneous addition of the cooled sol at a flow rate of 195 g/min and sulfuric acid (having a concentration of 80 g/L) at a flow rate allowing the pH to be set to 4 was carried out over 40 minutes. A maturation step lasting 10 minutes was performed.

40 minutes after the simultaneous sol/sulfuric acid addition, sodium silicate at a flow rate of 76 g/min for 20 minutes (the same sodium silicate as for the first simultaneous addition) and to maintain the pH of the reaction mixture at a value of 4. There was a simultaneous addition of sulfuric acid (80 g/L) with a flow rate set at . After 20 minutes, the acid flow was stopped until a pH of 8 was obtained.

A new co-addition was carried out over 60 minutes at a sodium silicate flow rate of 76 g/min (same sodium silicate as for the first co-addition) and sulfuric acid (80 g) set to maintain the pH of the reaction mixture at a value of 8. /L). The stirring speed was increased when the mixture became very viscous.

After this simultaneous addition, the reaction mixture was brought to a pH of 4 with sulfuric acid having a concentration of 80 g/L for 5 minutes. The mixture was aged at pH 4 for 10 minutes.
The slurry was filtered and washed under vacuum (15% cake solids) and after dilution the resulting cake was mechanically broken up. The resulting slurry was spray dried by a turbine spray dryer to obtain Silica-3.

The hydrogen release rates of CB-1 to CB-3 are as follows: (1) the carbon black sample is dried in a constant temperature dryer at 105 ° C. for 1 hour, cooled to room temperature (23 ° C.) in a desiccator, and (2) made of tin Approximately 10 mg was accurately weighed into a tube-shaped sample container, crimped and sealed, and (3) using a gas chromatograph ("GC-9A" manufactured by Shimadzu Corporation), under an argon stream, heated at 2000 ° C. for 15 minutes. The amount of hydrogen gas generated was measured at that time, and the amount of hydrogen gas generated was expressed in mass %.

As is clear from Tables 4 and 5, the vulcanized rubbers of Comparative Examples impair either wear resistance or crack resistance, whereas the vulcanized rubbers of Examples impair fuel efficiency. It can be seen that both wear resistance and crack resistance are excellent.
Example 1 and Comparative Example 3; Example 2 and Comparative Example 4; The comparative example has a different component composition in that the fatty acid metal salt-1 is used. As can be seen from the respective comparisons, the crack resistance of Example 1 is superior to Comparative Example 3, Example 2 is superior to Comparative Example 4, and Example 3 is superior to Comparative Example 5. .
If the vulcanized rubbers of Examples are applied to tires, it is expected that the tires will be excellent in both wear resistance and crack resistance without impairing fuel efficiency.

By using the rubber composition of the present invention, a tire having excellent wear resistance and crack resistance can be obtained without impairing fuel efficiency. for light trucks and heavy loads {for trucks and buses, for off-the-road tires (for mining vehicles, construction vehicles, small trucks, etc.)}, etc. .

1 Carbon black production furnace 10 Reaction chamber 11 Reaction continuation and cooling chamber 12 Multi-stage rapid refrigerant introduction means

Claims (5)

a filler (A) containing carbon black (A1) having a cetyltrimethylammonium bromide specific surface area of 30 to 150 m ² /g and silica (A2) having a cetyltrimethylammonium bromide specific surface area of 210 m ² /g or more;
a rubber component (B) comprising a diene-based polymer that constitutes a continuous phase and a diene-based polymer that constitutes a discontinuous phase and has an affinity for the filler (A);
a fatty acid metal salt (C);
contains
The content of the filler (A) is 30 to 80 parts by mass with respect to 100 parts by mass of the rubber component (B),
A rubber composition in which the ratio of the content (a1) of the carbon black (A1) to the content (a2) of the silica (A2) is (a1):(a2)=70 to 95:30 to 5 There is
The rubber component (B) contains 50 to 95% by mass of a diene polymer that constitutes the continuous phase, and a diene polymer that constitutes the discontinuous phase and has an affinity for the filler (A). Contains 5 to 50% by mass,
The diene-based polymer constituting the continuous phase contains natural rubber,
The diene-based polymer that constitutes the discontinuous phase and has an affinity for the filler (A) includes a modified conjugated diene-based polymer that has at least one functional group that has an affinity for the filler (A). ,
the functional group possessed by the modified conjugated diene-based polymer contains at least one atom selected from the group consisting of a nitrogen atom, an oxygen atom, and a silicon atom;
The modified conjugated diene-based polymer is modified polybutadiene,
The fatty acid metal salt (C) is a saturated fatty acid metal salt, an unsaturated fatty acid metal salt, or a mixture thereof, and the content of the fatty acid metal salt (C) is 100 parts by mass of the rubber component (B). 0.1 to 10 parts by mass of the rubber composition. 2. The rubber composition according to claim 1 , wherein the content of the fatty acid is 0 to 0.5 parts by mass with respect to 100 parts by mass of the rubber component (B). The rubber composition according to claim 1 or 2, wherein the carbon black (A1) has a hydrogen release rate higher than 0.3% by mass. A rubber composition for tire treads comprising the rubber composition according to any one of claims 1 to 3 . A tire using the rubber composition according to any one of claims 1 to 3 for a tread.

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