JP7155715B2 - Rubber composition and pneumatic tire - Google Patents

Description

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

In recent years, along with the demand for safety and fuel efficiency of automobiles, simultaneous improvement of wear resistance and fuel efficiency has been demanded in rubber materials for tires.

Conventionally, in order to solve such problems, a method using fine particle carbon black capable of imparting high reinforcing properties and excellent wear resistance has been implemented (for example, Patent Documents 1 and 2 reference).

However, there is room for improvement in that the use of fine particle carbon black generally tends to result in deterioration of processability due to increased viscosity of the rubber composition and accompanying deterioration in filler dispersibility. .

WO2014/181776 WO2014/189102

An object of the present invention is to solve the above problems and to provide a rubber composition having good processability, wear resistance, fuel efficiency and breaking strength, and a pneumatic tire using the same.

As a result of intensive studies on methods for solving the above problems, the present inventors have found that by using a specific carbon black, good workability, wear resistance, fuel efficiency and breaking strength (in particular, wear resistance and breaking strength) can be obtained, and conceived of the present invention.
That is, the present invention provides a rubber composition containing 2 to 200 parts by mass of carbon black having a hydrogen release rate of 0.20% by mass or more and a nitrogen adsorption specific surface area of 230 to 280 m ² /g with respect to 100 parts by mass of the rubber component. about things.

The carbon black preferably has an oil absorption amount of 80 to 140 cm ³ /100 g when compressed.

The carbon black preferably has a maximum frequency Stokes equivalent diameter of 30 to 100 nm.

The carbon black preferably has a Stokes equivalent half width of 20 to 80 nm.

The rubber composition is preferably a tire rubber composition.

The present invention also relates to a pneumatic tire having a tread made using the above rubber composition.

According to the present invention, since it is a rubber composition containing specific carbon black, it has good processability, abrasion resistance, fuel efficiency and breaking strength, and is excellent in abrasion resistance, fuel efficiency and breaking strength. We can provide pneumatic tires.

The rubber composition of the present invention contains 2 carbon blacks having a hydrogen release rate of 0.20% by mass or more and a nitrogen adsorption specific surface area (N ₂ SA) of 230 to 280 m ² /g with respect to 100 parts by mass of the rubber component. Contains up to 200 parts by mass. Thereby, good workability, wear resistance, fuel efficiency and breaking strength can be obtained. Although the reason why such effects are obtained is not necessarily clear, it is speculated as follows.

The present inventors' studies have revealed that the hydrogen release rate of carbon black and N ₂ SA have the following tendencies.
When the carbon black is pulverized into fine particles to increase the N ₂ SA specific surface area of the carbon black, the interaction with the polymer is increased and the reinforcing property is improved. However, atomization of carbon black tends to increase the viscosity of the kneaded rubber and deteriorate the dispersion of carbon black in the kneaded rubber. The hydrogen release rate is an index of the surface activity of carbon black, and the higher the hydrogen release rate, the higher the surface activity. A highly activated carbon black surface improves the dispersion of the carbon black in the compounded rubber. Therefore, by highly activating the surface of the fine particle carbon black, the dispersion of the fine particle carbon black in the compounded rubber is improved, and the effect of improving the wear resistance and fuel efficiency of the fine particle carbon black can be exhibited more preferably. We speculated that it would be possible, and conducted a study. As a result, by setting the hydrogen release rate to 0.20% by mass or more and setting the N ₂ SA to 230 [m ² /g] or more, compared with the case where the N ₂ SA is less than 230 [m ² /g] As a result, it was found that wear resistance can be remarkably improved while maintaining good fuel efficiency. If the N ₂ SA is more than 280 [m ² /g], the carbon black significantly deteriorates the workability, and due to the deterioration of the dispersion of the carbon black, the fuel efficiency and wear resistance deteriorate.
In the present invention, by highly activating the surface of the fine particle carbon black, the dispersion of the fine particle carbon black in the compounded rubber is improved, and the effect of compounding the fine particle carbon black is sufficiently obtained. Reinforcement is synergistically improved by improving the dispersion of carbon black in the compounded rubber through activation and by reducing the carbon black to fine particles to improve reinforcement. Fuel efficiency and breaking strength are obtained, and especially breaking strength and wear resistance are improved.

In the present invention, the hydrogen release rate of carbon black is 0.20% by mass or more, and the effect of blending fine particle carbon black with N ₂ SA of 230 to 280 m ² /g is sufficiently obtained by highly activating the surface. It is considered that the reinforcing properties are synergistically improved, and good workability, wear resistance, low fuel consumption and breaking strength are obtained.

(rubber composition)
The rubber composition contains carbon black (1) having a hydrogen release rate of 0.20% by mass or more and a nitrogen adsorption specific surface area of 230 to 280 m ² /g. Carbon black (1) may be used alone or in combination of two or more.

Carbon black (1) has a hydrogen release rate of 0.20% by mass or more, preferably 0.21% by mass or more, and more preferably 0.22% by mass or more. Although the upper limit is not particularly limited, it is preferably 0.50% by mass or less, more preferably 0.30% by mass or less. When the hydrogen release rate is within the above range, the effect is preferably obtained.
In this specification, the hydrogen release rate of carbon black is measured by drying the carbon black in a constant temperature dryer at 105° C. for 1 hour, cooling it to room temperature in a desiccator, and placing it in a tin tube-shaped sample container. Then, the amount of hydrogen gas generated was measured by a hydrogen analyzer and heated at 2000° C. for 15 minutes under an argon stream, and expressed as a mass fraction.

Carbon black (1) has a nitrogen adsorption specific surface area (N ₂ SA) of 230 to 280 m ² /g, preferably 235 m ² /g or more, more preferably 240 m ² /g or more, still more preferably 245 m 2 /g or more. ² /g or more, preferably 275 m ² /g or less, more preferably 270 m ² /g or less. When the N ₂ SA specific surface area is within the above range, the effect is preferably obtained.
In this specification, the N ₂ SA of carbon black is determined according to JIS K 6217-2:2001.

The dibutyl phthalate (DBP) oil absorption of carbon black (1) is preferably 80 cm ³ /100 g or more, more preferably 100 cm ³ /100 g or more, still more preferably 120 cm ³ /100 g or more, and preferably 150 cm ³ /100 g or more. It is 100 g or less, more preferably 140 cm ³ /100 g or less, and even more preferably 135 cm ³ /100 g or less. Within the above range, the effect can be obtained more favorably.
In this specification, the DBP oiling amount of carbon black is a value measured according to JIS K6217-4:2001.

The compressed oil absorption (COAN) of carbon black (1) is preferably 80 cm ³ /100 g or more, more preferably 90 cm ³ /100 g or more, still more preferably 100 cm ³ /100 g or more, and preferably 140 cm ³ . /100 g or less, more preferably 130 cm ³ /100 g or less, and even more preferably 120 cm ³ /100 g or less. When COAN is within the above range, the effect can be obtained more preferably.
In this specification, COAN of carbon black is a value measured using dibutyl phthalate in accordance with JIS K 6217-4:2001.

Carbon black (1) has a cetyltrimethylammonium bromide (CTAB) specific surface area of preferably 120 m ² /g or more, more preferably 150 m ² /g or more, still more preferably 165 m ² /g or more, and preferably 220 m 2 /g or more. ² /g or less, more preferably 200 m ² /g or less, still more preferably 185 m ² /g or less. When the CTAB specific surface area is within the above range, the effect can be obtained more preferably.
In this specification, the CTAB specific surface area of carbon black is a value measured according to JIS K6217-3:2001.

The maximum frequency Stokes equivalent diameter (D _mod ) of carbon black (1) is preferably 30 nm or more, more preferably 35 nm or more, still more preferably 45 nm or more, and preferably 100 nm or less, more preferably 85 nm or less, and further It is preferably 65 nm or less. D _mod is a typical size of aggregates of carbon black, and when D _mod is within the above range, the effect can be obtained more preferably.

The Stokes equivalent half width (D _1/2 ) of the carbon black (1) is preferably 20 nm or more, more preferably 25 nm or more, still more preferably 35 nm or more, and is preferably 80 nm or less, more preferably 70 nm or less. , and more preferably 55 nm or less. D _1/2 is an index representing the spread of the aggregate size distribution of carbon black, and when D _1/2 is within the above range, the effect can be obtained more preferably.

In addition, in this specification, D _mod and D _1/2 are values measured by the following method.
A precisely weighed carbon black sample is added to a 20% aqueous ethanol solution containing a surfactant ("NONIDET P-40" manufactured by SIGMA CHEMICAL) to prepare a sample solution having a carbon black concentration of 0.01% by mass. A carbon black slurry is prepared by subjecting this sample liquid to dispersion treatment for 5 minutes using an ultrasonic disperser (“Ultrasonic Generator USV-500V” manufactured by Ultrasonic Industry) at a frequency of 200 kHz and an output of 100 W. On the other hand, 10 ml of spin liquid (pure water) was injected into a centrifugal sedimentation type particle size distribution analyzer ("BI-DCP PARTICLSIZER" manufactured by BROOK HAVEN INSTRUMENTS), and 1 ml of buffer solution (20% ethanol aqueous solution) was further injected. After that, 1 ml each of the carbon black slurry prepared above is injected and sedimented by centrifugation at a rotation speed of 10000 rpm to measure the Stokes equivalent diameter and create a histogram of the frequency of occurrence relative to the Stokes equivalent diameter. Let C be the intersection of a straight line parallel to the Y-axis passing through the peak (A) of the histogram and the X-axis of the histogram. The Stokes diameter at C is defined as the maximum frequency Stokes equivalent diameter (D _mod ). Also, with the midpoint of the line segment AC as F, the two points of intersection (D, E) between the distribution curve of the histogram and the straight line G passing through F parallel to the X axis are obtained. Let the absolute value be the Stokes equivalent radius half width value (D _1/2 ).

The content of the carbon black (1) may be 2 to 200 parts by mass with respect to 100 parts by mass of the rubber component, preferably 5 parts by mass or more, more preferably 10 parts by mass or more, still more preferably 20 parts by mass. It is at least 150 parts by mass, more preferably at most 100 parts by mass, and even more preferably at most 80 parts by mass. When the content of carbon black (1) is within the above range, the effect can be obtained more preferably.

In the rubber composition, carbon black other than carbon black (1) may be used together with carbon black (1). The total content of carbon black in this case may be the same amount as in the case of using carbon black (1) alone.

The above carbon black (1) can be produced by a known production method if the above target properties are determined by those skilled in the art. The production method is not particularly limited, but specifically, it is preferable to adopt a method of producing carbon black by spraying raw material oil into combustion gas, for example, conventionally known methods such as furnace method and channel method method is used. Among them, the following furnace method is preferable.

In the furnace method (oil furnace method), for example, as disclosed in JP-A-2004-43598, JP-A-2004-277443, etc., a raw material is added to a combustion zone in which a high-temperature combustion gas flow is generated in a reactor, and a high-temperature combustion gas flow. A process using an apparatus having a reaction zone in which hydrocarbons are introduced to convert raw hydrocarbons into carbon black by a pyrolysis reaction, and a reaction stop zone in which the reaction gas is quenched to stop the reaction, wherein the combustion conditions, high temperature Carbon blacks with various properties can be produced by controlling various conditions such as the flow rate of combustion gas, the conditions for introducing feedstock oil into the reactor, and the time from conversion of carbon black to termination of the reaction.

In the combustion zone, the oxygen-containing gas, air, oxygen or mixtures thereof, and gaseous or liquid fuel hydrocarbons are mixed and combusted to form hot combustion gases. As fuel hydrocarbons, carbon monoxide, natural gas, coal gas, petroleum gas, petroleum liquid fuels such as heavy oil, and coal liquid fuels such as creosote oil are used. Combustion is preferably controlled so that the combustion temperature is in the range of 1400°C to 2000°C.

In the reaction zone, the feedstock hydrocarbon is sprayed from a burner provided cocurrently or laterally with the high-temperature combustion gas stream obtained in the combustion zone, and the feedstock hydrocarbon is thermally decomposed and converted into carbon black. Preferably, the feedstock is introduced by one or more burners into the hot combustion gas stream with a gas velocity in the range of 100-1000 m/s. It is preferable to divide and introduce the raw material oil by two or more burners. In addition, it is preferable to provide a constricted portion in the reaction zone in order to improve the reaction efficiency. The ratio of the diameter of the narrowed portion to the diameter of the upstream area of the narrowed portion is preferably 0.1 to 0.8.

In the reaction stopping zone, water spraying or the like is performed to cool the high-temperature reaction gas to 1000 to 800° C. or below. The time from the introduction of the raw material oil to the termination of the reaction is preferably 2 to 100 milliseconds. After the cooled carbon black is separated and recovered from the gas, it can undergo known processes such as granulation and drying.

Specific examples of feedstock oils include (1) aromatic hydrocarbons such as anthracene; coal-based hydrocarbons such as creosote oil; ) and (2) a mixed feedstock of an aliphatic hydrocarbon. In addition, these may be modified. Among them, a mixed raw material oil of coal-based hydrocarbons and aliphatic hydrocarbons is preferable.

Examples of aliphatic hydrocarbons that can be used include petroleum-based aliphatic hydrocarbons typified by process oils, and animal and vegetable oils typified by fatty acids such as soybean oil, rapeseed oil, and palm oil.
Here, the animal and vegetable oils include marine animal oils such as fatty oils (liver oils) obtained from fish livers and marine animal oils obtained from whales, land animal oils such as beef tallow and pork tallow, as well as plant seeds, fruits, and kernels. It contains oils and fats composed of fatty acid glycerides collected from, for example.

Examples of usable rubber components include diene rubbers such as isoprene rubber, butadiene rubber (BR), styrene butadiene rubber (SBR), and styrene isoprene butadiene rubber (SIBR). A rubber component may be used independently and may use 2 or more types together. Among them, SBR, BR, and isoprene-based rubber (especially isoprene-based rubber) are preferable because the effect can be obtained more preferably. is more preferred.

SBR is not particularly limited, and for example, emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), etc. can be used. These may be used alone or in combination of two or more.

BR is not particularly limited, and for example, BR with a high cis content, BR containing syndiotactic polybutadiene crystals, and the like can be used. These may be used alone or in combination of two or more. Above all, the cis content of BR is preferably 90% by mass or more because the wear resistance is good.

SBR and BR may be modified.
The modified SBR and modified BR may have a functional group that interacts with a filler such as carbon black. For example, at least one end of the polymer is modified with a compound (modifier) having the above functional group. terminal-modified rubber (terminal-modified rubber having the above-mentioned functional group at the end), main-chain-modified rubber having the above-mentioned functional group in the main chain, and main-chain-end-modified rubber having the above-mentioned functional group in the main chain and terminal (for example, , main chain terminal modified BR having the above functional group in the main chain and at least one end modified with the above modifying agent), and modified with a polyfunctional compound having two or more epoxy groups in the molecule (coupling ), and terminal-modified rubber into which a hydroxyl group or an epoxy group is introduced. These may be used alone or in combination of two or more.

Examples of the functional groups include amino group, amido group, silyl group, alkoxysilyl group, isocyanate group, imino group, imidazole group, urea group, ether group, carbonyl group, oxycarbonyl group, mercapto group, sulfide group, disulfide group, sulfonyl group, sulfinyl group, thiocarbonyl group, ammonium group, imide group, hydrazo group, azo group, diazo group, carboxyl group, nitrile group, pyridyl group, alkoxy group, hydroxyl group, oxy group, epoxy group and the like. . In addition, these functional groups may have a substituent. Among them, amino group (preferably an amino group in which the hydrogen atom of the amino group is substituted with an alkyl group having 1 to 6 carbon atoms), alkoxy group (preferably 1 carbon atom 6 alkoxy groups) and alkoxysilyl groups (preferably alkoxysilyl groups having 1 to 6 carbon atoms) are preferred.

As SBR and BR, for example, products of Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Zeon Corporation, etc. can be used.

When SBR is contained, the content of SBR in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 45% by mass or more, and preferably 90% by mass or less, more preferably 85% by mass. % or less, more preferably 65 mass % or less. Within the above range, the effect tends to be obtained more favorably.

When BR is contained, the content of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass. % or less, more preferably 30 mass % or less. Within the above range, the effect tends to be obtained more favorably.

Examples of isoprene rubber include natural rubber (NR), isoprene rubber (IR), modified natural rubber, modified NR, modified IR, and the like. As NR, for example, those commonly used in the tire industry, such as SIR20, RSS#3, and TSR20, can be used. The IR is not particularly limited, and for example IR2200 or the like commonly used in the tire industry can be used. Modified natural rubber includes high-purity natural rubber (UPNR), etc. Modified NR includes epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. Modified IR includes epoxidized rubber. Examples include isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, and the like. These may be used alone or in combination of two or more. Among them, natural rubber (NR) is preferable.

When isoprene-based rubber is contained, the content of isoprene-based rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more, and particularly preferably 20% by mass. % by mass or more. Also, it is preferably 95% by mass or less, more preferably 90% by mass or less, still more preferably 85% by mass or less, and particularly preferably 80% by mass or less. Moreover, when SBR is contained, it is more preferably 60% by mass or less, particularly preferably 40% by mass or less. Within the above range, the effect tends to be obtained more favorably.

The rubber composition may contain a resin.
As used herein, the term "resin" means a polymer compound, more specifically, a polymer obtained by polymerizing monomer units, and may be solid or liquid.
The resin is not particularly limited as long as it is commonly used in the tire industry. resins, C9-based resins, and the like. These may be used alone or in combination of two or more. Among them, polyalkylene resins and terpene-based resins are preferable because they can plasticize the rubber, promote the dispersion of the filler, and obtain more favorable effects.

The polyalkylene resin is not particularly limited as long as it has a unit derived from alkylene, and examples thereof include polyethylene resins, polypropylene resins, polybutylene resins, ethylene propylene resins, ethylene propylene styrene resins, ethylene styrene resins, propylene styrene resins, and the like. is mentioned. Among them, ethylene propylene resin and ethylene propylene styrene resin are preferable.

The terpene-based resin is not particularly limited as long as it has a unit derived from a terpene compound. Examples include polyterpene (resin obtained by polymerizing a terpene compound), terpene aromatic resin (a resin obtained by copolymerizing), aromatic modified terpene resin (resin obtained by modifying terpene resin with an aromatic compound), and the like.

The above terpene compounds are hydrocarbons represented by the composition (C ₅ H ₈ ) _n and oxygen-containing derivatives thereof, and include monoterpene (C ₁₀ H ₁₆ ), sesquiterpene (C ₁₅ H ₂₄ ), diterpene (C ₂₀ H ₃₂ ), etc., which are compounds having a terpene as a basic skeleton, such as α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineol, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol and the like. The terpene compounds also include resin acids (rosin acids) such as abietic acid, neoabietic acid, parastric acid, levopimaric acid, pimaric acid and isopimaric acid. That is, the terpene-based resins include rosin-based resins containing rosin acid obtained by processing rosin as a main component. The rosin resins include naturally occurring rosin resins (polymerized rosins) such as gum rosin, wood rosin, and tall oil rosin, modified rosin resins such as maleic acid-modified rosin resins and rosin-modified phenol resins, and rosin glycerin esters. Examples include rosin esters and disproportionated rosin resins obtained by disproportionating rosin resins.

The aromatic compound is not particularly limited as long as it is a compound having an aromatic ring. Examples include phenol compounds such as phenol, alkylphenol, alkoxyphenol, unsaturated hydrocarbon group-containing phenol; Naphthol compounds such as saturated hydrocarbon group-containing naphthol; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, and unsaturated hydrocarbon group-containing styrene; Among these, styrene is preferred.

The softening point of the resin is preferably 0°C or higher, more preferably 10°C or higher, and even more preferably 40°C or higher. Also, the softening point is preferably 160° C. or lower, more preferably 140° C. or lower, and even more preferably 100° C. or lower. Within the above range, the effect can be obtained more favorably.
In the present specification, the softening point of the resin is the temperature at which the softening point defined in JIS K 6220-1:2001 is measured with a ring and ball type softening point measuring device, and the ball descends.

The resin may be a hydrogenated one, and the resin is preferably a hydrogenated resin because the effect can be obtained more suitably. The hydrogenation can be carried out by a known method, and for example, catalytic hydrogenation using a metal catalyst, a method using hydrazine, and the like can be preferably used (JP-A-59-161415, etc.). For example, catalytic hydrogenation using a metal catalyst can be carried out by adding hydrogen under pressure in the presence of a metal catalyst in an organic solvent. can be used for These organic solvents can be used singly or in combination of two or more. Moreover, as the metal catalyst, for example, palladium, platinum, rhodium, ruthenium, nickel, etc. can be suitably used. These metal catalysts can be used singly or in combination of two or more. . The pressure when pressurizing is preferably, for example, 1 to 300 kgf/cm ² .

In the above resin, the hydrogenation rate of double bonds is 1 to 100%, preferably 2% or more, more preferably 5% or more, and even more preferably 8% or more. . In addition, the upper limit of the hydrogenation rate of the double bond may be changed due to the pressurized heating conditions in the hydrogenation reaction, progress in manufacturing technology such as catalysts, improvement in productivity, etc. Although it cannot be accurately confirmed at the present time, at present, for example, it is preferably 80% or less, more preferably 60% or less, further preferably 40% or less, and even more preferably 30% or less. 25% or less is particularly preferred.
The hydrogenation rate (hydrogenation rate) is a value calculated by the following formula from each integrated value of the double bond-derived peak in ¹ H-NMR (proton NMR). As used herein, the hydrogenation rate (hydrogenation rate) means the hydrogenation rate of a double bond.
(Hydrogenation rate [%]) = {(AB) / A} × 100
A: Integrated value of double bond peak before hydrogenation B: Integrated value of double bond peak after hydrogenation

Examples of resins include Mitsui Chemicals, Structol, Yasuhara Chemicals, Arizona Chemicals, Nichinuri Chemicals, Rutgers Chemicals, Arakawa Chemical Industries, Maruzen Petrochemicals, Products of Sumitomo Bakelite Co., Ltd., Tosoh Co., Ltd., Nippon Shokubai Co., Ltd., JX Energy Co., Ltd., Toagosei Co., Ltd., etc. can be used.

When a resin is contained, the content of the resin is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and still more preferably 5 parts by mass or more with respect to 100 parts by mass of the rubber component. It is 50 parts by mass or less, more preferably 30 parts by mass or less, and still more preferably 15 parts by mass or less. Thereby, an effect is obtained more suitably.

The rubber composition may contain silica.
Examples of silica include dry silica (anhydrous silicic acid) and wet silica (hydrated silicic acid), but wet silica is preferred because it contains many silanol groups. These may be used alone or in combination of two or more.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 70 m ² /g or more, more preferably 150 m ² /g or more. By making it 70 m ² /g or more, abrasion resistance, breaking strength, etc. tend to be further improved. The N ₂ SA of the silica is preferably 500 m ² /g or less, more preferably 200 m ² /g or less. By making it 500 m ² /g or less, workability tends to be further improved.
The nitrogen adsorption specific surface area of silica is a value measured by the BET method according to ASTM D3037-81.

As silica, for example, products of Degussa, Rhodia, Tosoh Silica, Solvay Japan, Tokuyama, etc. can be used.

When silica is contained, the content of silica is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, and still more preferably 50 parts by mass or more with respect to 100 parts by mass of the rubber component. When the amount is 20 parts by mass or more, the fuel efficiency tends to be further improved. Also, the content is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, and even more preferably 100 parts by mass or less. When the amount is 200 parts by mass or less, the balance between workability and fuel efficiency tends to be further improved.

The content of carbon black in the total 100% by mass of silica and carbon black is preferably 20% by mass or more, more preferably 50% by mass or more, and still more preferably 80% by mass or more. good. Thereby, an effect is obtained more suitably.

When the rubber composition contains silica, it preferably further contains a silane coupling agent.
The silane coupling agent is not particularly limited, and examples thereof include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, Bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (2-triethoxysilylethyl) trisulfide, bis (4-trimethoxysilylbutyl) trisulfide, bis ( 3-triethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl) disulfide, bis(4-triethoxysilylbutyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(2-trimethoxysilylethyl) ) disulfide, bis(4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3- sulfides such as triethoxysilylpropyl methacrylate monosulfide; 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane; vinyl such as methoxysilane; amino such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. These may be used alone or in combination of two or more. Among them, a sulfide-based silane coupling agent is preferred because it tends to provide better effects.

Examples of silane coupling agents that can be used include products of Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azmax Co., Ltd., Dow Corning Toray Co., Ltd., and the like.

When a silane coupling agent is contained, the content of the silane coupling agent is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, relative to 100 parts by mass of silica. When the amount is 3 parts by mass or more, there is a tendency that the effect of addition can be obtained. In addition, the content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less. When it is 20 parts by mass or less, an effect commensurate with the blending amount is obtained, and there is a tendency to obtain good workability during kneading.

The rubber composition may contain oil.
Oils include, for example, process oils, vegetable oils, or mixtures thereof. As the process oil, for example, paraffinic process oil, aromatic process oil, naphthenic process oil, etc. can be used. Vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice bran oil, safflower oil, sesame oil, Olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, tung oil and the like. These may be used alone or in combination of two or more. Of these, process oils are preferred, and aroma-based process oils are more preferred, because they are more effective.

As oil, for example, Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Co., Ltd., Orisoi Co., Ltd., H & R, Toyokuni Oil Mills Co., Ltd., Showa Shell Oil Co., Ltd., Fuji Kosan Co., Ltd. etc. products can be used.

When oil is contained, the content of oil is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and preferably 30 parts by mass or less, more preferably 100 parts by mass of the rubber component. It is 20 parts by mass or less. Thereby, an effect is obtained more suitably.

The rubber composition may contain wax.
The wax is not particularly limited, and includes petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as plant waxes and animal waxes; synthetic waxes such as polymers of ethylene and propylene. These may be used alone or in combination of two or more. Among them, petroleum waxes are preferred, and paraffin waxes are more preferred.

As the wax, for example, products of Ouchi Shinko Kagaku Kogyo Co., Ltd., Nippon Seiro Co., Ltd., Seiko Kagaku Co., Ltd., etc. can be used.

When wax is contained, the content of wax is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, relative to 100 parts by mass of the rubber component, from the viewpoint of the above-mentioned performance balance, and , preferably 20 parts by mass or less, more preferably 10 parts by mass or less. Thereby, an effect is obtained more suitably.

The rubber composition may contain an antioxidant.
Examples of anti-aging agents include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4′-bis(α,α′-dimethylbenzyl)diphenylamine; -Isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylenediamine, etc. p-phenylenediamine-based antioxidants; quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; 2,6-di-t-butyl-4-methylphenol, monophenolic anti-aging agents such as styrenated phenol; inhibitors and the like. These may be used alone or in combination of two or more. Among them, p-phenylenediamine antioxidants and quinoline antioxidants are preferred.

As the anti-aging agent, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Kagaku Kogyo Co., Ltd., Flexis, etc. can be used, for example.

When an anti-aging agent is contained, the content of the anti-aging agent is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass with respect to 100 parts by mass of the rubber component. parts or less, more preferably 5 parts by mass or less. Thereby, an effect is obtained more suitably.

The rubber composition may contain stearic acid.
Conventionally known stearic acid can be used, for example, products of NOF Corporation, NOF, Kao Corporation, Fuji Film Wako Pure Chemical Industries, Ltd., Chiba Fatty Acids Co., Ltd. can be used.

When stearic acid is contained, the content of stearic acid is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less with respect to 100 parts by mass of the rubber component. , more preferably 5 parts by mass or less. Thereby, an effect is obtained more suitably.

The rubber composition may contain zinc oxide.
As the zinc oxide, conventionally known ones can be used, for example, products of Mitsui Kinzoku Mining Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used.

When zinc oxide is contained, the content of zinc oxide is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less with respect to 100 parts by mass of the rubber component. , more preferably 5 parts by mass or less. Thereby, an effect is obtained more suitably.

The rubber composition may contain sulfur.
Sulfur includes powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur and the like commonly used in the rubber industry. These may be used alone or in combination of two or more.

As sulfur, for example, products of Tsurumi Chemical Industry Co., Ltd., Karuizawa Io Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexis Co., Ltd., Nippon Kantan Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used.

When sulfur is contained, the content of sulfur is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and preferably 10 parts by mass or less with respect to 100 parts by mass of the rubber component. , more preferably 5 parts by mass or less, and still more preferably 3 parts by mass or less. Thereby, an effect is obtained more suitably.

The rubber composition may contain a vulcanization accelerator.
Vulcanization accelerators include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazylsulfenamide; tetramethylthiuram disulfide (TMTD ), tetrabenzyl thiuram disulfide (TBzTD), tetrakis (2-ethylhexyl) thiuram disulfide (TOT-N) and other thiuram vulcanization accelerators; N-cyclohexyl-2-benzothiazolesulfenamide, Nt-butyl- 2-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N,N'-diisopropyl-2-benzothiazolesulfenamide, etc. and guanidine-based vulcanization accelerators such as diphenylguanidine, diorthotolylguanidine and orthotolylbiguanidine. These may be used alone or in combination of two or more. Among them, sulfenamide-based vulcanization accelerators and guanidine-based vulcanization accelerators are preferable because they are more suitable for obtaining effects.

As the vulcanization accelerator, for example, products manufactured by Kawaguchi Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., Sanshin Chemical Industry Co., Ltd., etc. can be used.

When a vulcanization accelerator is contained, the content of the vulcanization accelerator is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 10 parts by mass with respect to 100 parts by mass of the rubber component. parts or less, more preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less. Thereby, an effect is obtained more suitably.

In addition to the above components, the rubber composition contains additives commonly used in the tire industry, such as organic peroxides; fillers such as calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica. ; and the like may be further added. The content of these additives is preferably 0.1 to 200 parts by mass with respect to 100 parts by mass of the rubber component.

The rubber composition can be produced, for example, by kneading the above components using a rubber kneading device such as an open roll mixer or a Banbury mixer, followed by vulcanization.

As for the kneading conditions, the kneading temperature is usually 100 to 180°C, preferably 120 to 170°C in the base kneading step in which additives other than the vulcanizing agent and the vulcanization accelerator are kneaded. In the finishing kneading step of kneading the vulcanizing agent and the vulcanization accelerator, the kneading temperature is usually 120°C or lower, preferably 80 to 110°C. A composition obtained by kneading a vulcanizing agent and a vulcanization accelerator is usually subjected to vulcanization treatment such as press vulcanization. The vulcanization temperature is generally 140-190°C, preferably 150-185°C. Vulcanization time is usually 5 to 15 minutes.

Examples of the rubber composition include tread (cap tread), sidewall, base tread, undertread, clinch, bead apex, breaker cushion rubber, carcass cord covering rubber, insulation, chafer, inner liner, etc. It can be used for tire members such as side reinforcing layers of run-flat tires (as a rubber composition for tires). Among others, it is preferably used for treads. The rubber composition can also be used for shoe sole rubber, anti-vibration rubber, belts, hoses, and other industrial rubber products.

The pneumatic tire of the present invention is manufactured by a normal method using the rubber composition. That is, a rubber composition blended with various additives as necessary is extruded in the unvulcanized stage according to the shape of each tire member (especially the tread (cap tread)), and is placed on a tire building machine. After forming an unvulcanized tire by molding by a normal method with other tire members and bonding together with other tire members to form an unvulcanized tire, the tire can be manufactured by heating and pressurizing in a vulcanizer.

At least a portion of the tire member (for example, tread) of the pneumatic tire may be composed of the rubber composition, or the entirety may be composed of the rubber composition.

The above pneumatic tires include passenger car tires, large passenger car tires, large SUV tires, truck and bus tires, motorcycle tires, competition tires, studless tires (winter tires), runflat tires, aircraft tires, and mining tires. It is suitable for use as a tire for automobiles and the like.

EXAMPLES The present invention will be specifically described based on Examples, but the present invention is not limited to these.

Various chemicals used in Examples and Comparative Examples will be collectively described.
NR: TSR20
SBR: Nipol 1502 manufactured by Nippon Zeon Co., Ltd.
BR: BR150B (cis content: 98% by mass) manufactured by Ube Industries, Ltd.
CB1-6: Carbon black (prototype) having the properties shown in Table 1 below
Silica: VN3 from Evonik Degussa (N ₂ SA: 175 m ² /g)
Silane coupling agent: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Evonik Degussa
Oil: Diana Process NH-70S (aromatic process oil) manufactured by Idemitsu Kosan Co., Ltd.
Zinc oxide: Type 3 zinc oxide manufactured by Hakusui Tech Co., Ltd. Stearic acid: Beads stearic acid "Tsubaki" manufactured by NOF Corporation
Sulfur: powdered sulfur (containing 5% oil) manufactured by Tsurumi Chemical Industry Co., Ltd.
Vulcanization accelerator: Noxceler NS (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.

(Examples and Comparative Examples)
According to the formulation shown in Tables 2 and 3, using a Banbury mixer manufactured by Kobe Steel, Ltd., materials other than sulfur and a vulcanization accelerator were kneaded at 150°C for 5 minutes to obtain a kneaded product. rice field. Next, sulfur and a vulcanization accelerator were added to the resulting kneaded material, and the mixture was kneaded at 80° C. for 5 minutes using an open roll to obtain an unvulcanized rubber composition. The resulting unvulcanized rubber composition was molded into a tread shape, laminated with other tire members to form an unvulcanized tire, press-vulcanized at 170 ° C. for 10 minutes, and a test tire ( Size: 195/65R15) was manufactured.
Further, the unvulcanized rubber composition was press-vulcanized at 170° C. for 10 minutes to obtain a vulcanized rubber composition.
The unvulcanized rubber compositions, vulcanized rubber compositions, and test tires thus obtained were used for the following evaluations.

(workability)
For each unvulcanized rubber composition, according to the Mooney viscosity measurement method according to JIS K 6300-1 "Unvulcanized rubber-Physical properties-Part 1: Determination of viscosity and scorch time by Mooney viscometer", The Mooney viscosity (ML1+4) was measured under the temperature condition of 130°C. The results are shown indexed (workability index) with the Mooney viscosity of Comparative Examples 1-1 and 2-1 being 100 for each table. The larger the index, the lower the Mooney viscosity and the better the workability. A score of 95 or more was judged to be good.

(wear resistance)
Each test tire was mounted on a domestic FF vehicle, and the groove depth of the tire tread portion was measured after a running distance of 8000 km, and the running distance when the tire groove depth decreased by 1 mm was calculated. The results are shown in each table as an index when the running distance of Comparative Examples 1-1 and 2-1 is set to 100 (wear resistance index). The larger the index, the longer the running distance when the tire groove depth is reduced by 1 mm, and the better the wear resistance.
A score of 95 or more was judged to be good.

(Low fuel consumption)
Using a rolling resistance tester, measure the rolling resistance when running the above test tire under the conditions of rim (15 x 6 JJ), internal pressure (230 kPa), load (3.43 kN), and speed (80 km / h). did. In each table, the rolling resistance of Comparative Examples 1-1 and 2-1 was set to 100 and indicated as an index (fuel efficiency index). A larger index indicates lower rolling resistance and better fuel efficiency.
A score of 95 or more was judged to be good.

(Breaking strength)
According to JIS K6251 "Determination of Tensile Properties of Vulcanized Rubber and Thermoplastic Rubber", a tensile test was performed using a No. 3 dumbbell to measure the breaking strength (TB) of the vulcanized rubber composition. In each table, the EB of Comparative Examples 1-1 and 2-1 was set to 100, and the TB of each formulation was indicated as an index (breaking strength index). A larger index indicates better breaking strength.
A score of 95 or more was judged to be good.

From Tables 2 and 3, the examples containing specific carbon black exhibited good workability, abrasion resistance, fuel economy and breaking strength (especially abrasion resistance and breaking strength).

Claims (7)

A rubber composition containing 2 to 200 parts by mass of carbon black having a hydrogen release rate of 0.20% by mass or more and a nitrogen adsorption specific surface area of 230 to 280 m ² /g based on 100 parts by mass of a rubber component. The rubber composition according to claim 1, wherein the carbon black has an oil absorption amount of 80 to 140 cm ³ /100 g under compression. 3. The rubber composition according to claim 1, wherein said carbon black has a maximum frequency Stokes equivalent diameter of 30 to 100 nm. The rubber composition according to any one of claims 1 to 3, wherein the carbon black has a Stokes equivalent half width of 20 to 80 nm. The carbon black has a dibutyl phthalate oil absorption of 80 to 150 cm. ³ / 100g, cetyltrimethylammonium bromide specific surface area 120-185m ² /g, the rubber composition according to any one of claims 1 to 4. The rubber composition according to any one of claims 1 to 5 , which is a rubber composition for tires. A pneumatic tire having a tread produced using the rubber composition according to any one of claims 1 to 6 .