JP2018145271A - Rubber composition for tire and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for a tire, having improved high mileage property, wet grip performance and wear resistance in a balanced manner, and a pneumatic tire manufactured by using the rubber composition.SOLUTION: The rubber composition for a tire comprises a styrene-butadiene rubber, a butadiene rubber and silica, in which in 100 mass% of the rubber component, the content of the styrene-butadiene rubber is 40 mass% or more and the content of the butadiene rubber is 20 mass% or more, with respect to 100 parts by mass of the rubber component, the content of the silica is 50 parts by mass or more, and the styrene-butadiene rubber has an average molecular weight of 300000 or less and an average vinyl amount of 40 mass% or more.SELECTED DRAWING: None

Description

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

In recent years, due to increasing interest in environmental issues, there has been a strong demand for lower fuel consumption for automobiles, and rubber compositions used for automobile tires are also required to have excellent fuel efficiency. .

As a method for improving fuel economy, for example, a method of reducing the amount of reinforcing filler is known, but in this method, wet grip performance and wear resistance are reduced due to a decrease in the calorific value and reinforcement of the rubber composition. Etc. tend to get worse. Thus, these performances generally have a contradiction with low fuel consumption, and it is difficult to obtain each performance in a well-balanced manner.

The present invention solves the above-mentioned problems, and provides a rubber composition for a tire having improved fuel economy, wet grip performance and wear resistance in a well-balanced manner, and a pneumatic tire produced using the rubber composition. Objective.

The present invention includes styrene butadiene rubber, butadiene rubber and silica, wherein the content of the styrene butadiene rubber in 100% by mass of the rubber component is 40% by mass or more, the content of the butadiene rubber is 20% by mass or more, and the rubber component 100 The silica content with respect to parts by mass is 50 parts by mass or more, and the styrene butadiene rubber relates to a rubber composition for tires having an average molecular weight of 300,000 or less and an average vinyl content of 40% by mass or more.

It is preferable that the nitrogen adsorption specific surface area of silica is 150 m ² / g or more.
The content of carbon black having a CTAB specific surface area of 150 m ² / g or more with respect to 100 parts by mass of the rubber component is preferably 10 to 40 parts by mass.

The content of the C5 resin with respect to 100 parts by mass of the rubber component is preferably 1 part by mass or more.
The present invention also relates to a pneumatic tire produced using the rubber composition.

According to the present invention, since it is a rubber composition for tires containing styrene butadiene rubber having a predetermined average molecular weight and an average vinyl amount, butadiene rubber, and silica in a predetermined ratio, low fuel consumption, wet grip performance and anti-resistance Abrasion is improved with good balance.

The rubber composition for tires of the present invention contains styrene butadiene rubber (SBR) having a predetermined average molecular weight and an average vinyl amount, butadiene rubber (BR), and silica at a predetermined ratio.

The rubber composition has the above-mentioned effects, which are presumed to be achieved by the following effects.
In a compound system containing a large amount of SBR having a low molecular weight and a large amount of vinyl, performance other than wet grip performance tends to deteriorate, but by blending BR by 20 mass% or more and silica by 50 mass parts or more, low It is considered that the performance balance of fuel efficiency, wet grip performance and wear resistance is remarkably improved (synergistically).

Furthermore, (1) a silica adsorption specific surface area of 150 m ² / g or more is used as silica, (2) 10 to 40 parts by mass of carbon black having a CTAB specific surface area of 150 m ² / g or more, (3) C5 resin It is considered that the performance balance is improved more remarkably (synergistically) by applying at least one method of blending 1 part by mass or more.

The SBR contained in the rubber composition has an average molecular weight of 300,000 or less. The average molecular weight is preferably 270,000 or less, more preferably 250,000 or less, from the viewpoint of the performance balance. Although a lower limit is not specifically limited, Similarly, from a viewpoint of the said performance balance, 100,000 or more are preferable, 120,000 or more are more preferable, and 140,000 or more are still more preferable.

Here, the average molecular weight of SBR (average molecular weight of all SBR) is Σ (content ratio of each SBR in all SBR × weight average molecular weight of each SBR), and the content ratio of each SBR is the respective ratio in all SBR. SBR (A), (B) in the case of a rubber component consisting of SBR (A) 50 mass%, SBR (B) 5 mass%, NR 15 mass%, BR 30 mass% The content ratios are 0.909 (= 50 / (50 + 5)) and 0.091 (= 5 / (50 + 5)), respectively, so that, for example, the rubber component is SBR (A) (styrene content 25% by mass, vinyl SBR (B) (styrene content 35% by mass, vinyl content 35% by mass, Mw 1.05%) 5% by mass, NR 15% by mass, BR 30% by mass, SBR average Molecular weight , 23.181 million (231,818 = 50 / (50 + 5) × 150,000 + 5 / (50 + 5) × 1,0550,000).

The SBR contained in the rubber composition has an average vinyl content of 40% by mass or more. The lower limit of the average vinyl content is preferably 45% by mass or more and more preferably 47% by mass or more from the viewpoint of the performance balance. Similarly, from the viewpoint of the performance balance, the upper limit is preferably 70% by mass or less, more preferably 65% by mass or less, and still more preferably 62% by mass or less.

Here, the average vinyl amount of SBR is {Σ (content ratio of each SBR in all SBR × vinyl amount of each SBR × weight average molecular weight of each SBR)} / average molecular weight of all SBRs. For example, the rubber component is SBR (A) (styrene content 25% by mass, vinyl content 60% by mass, Mw 150,000) 50% by mass, SBR (B) (styrene content 35% by mass, vinyl content 35% by mass, Mw 1.05 million) In the case of 5 mass%, NR 15 mass%, and BR 30 mass%, the average vinyl content is 49.7 mass% (= {50 / (50 + 5) × 60 × 150,000 + 5 / (50 + 5) × 35 × 1,050}) / 23.1818 million).

The amount of styrene in each SBR is preferably 15% by mass or more, more preferably 20% by mass or more. There exists a tendency for favorable wet grip performance to be acquired by making it more than a minimum. The amount of styrene is preferably 50% by mass or less, more preferably 45% by mass or less. By setting it to the upper limit or less, heat generation is reduced, and good fuel economy tends to be obtained.
The amount of styrene can be measured by the method described in the examples below.

The amount of vinyl in each SBR is preferably 20% by mass or more, more preferably 30% by mass or more. There exists a tendency for favorable wet grip performance to be acquired by making it more than a minimum. The vinyl content is preferably 65% by mass or less, more preferably 60% by mass or less. By setting it to the upper limit or less, good wear resistance tends to be obtained.
The vinyl amount (1,2-bonded butadiene unit amount) can be measured by the method described in the examples below.

The weight average molecular weight Mw of each SBR is preferably 100,000 or more, more preferably 120,000 or more. By setting the lower limit or more, good low fuel consumption and wear resistance tend to be obtained. The Mw is preferably 1.1 million or less, more preferably 1.05 million or less. There exists a tendency for favorable workability to be acquired by making it into an upper limit or less.
The SBR preferably contains at least one SBR having a Mw of 400,000 or less (preferably 300,000 or less, more preferably 200,000 or less) from the viewpoint of the performance balance.
In addition, Mw can be measured by the method as described in the below-mentioned Example.

The content of SBR in 100% by mass of the rubber component is 40% by mass or more, preferably 45% by mass or more, and more preferably 50% by mass or more from the viewpoints of wet grip performance and wear resistance. The content is preferably 90% by mass or less, more preferably 80% by mass or less, and still more preferably 75% by mass or less from the viewpoint of low fuel consumption.

It does not specifically limit as SBR, For example, emulsion polymerization styrene butadiene rubber (E-SBR), solution polymerization styrene butadiene rubber (S-SBR), etc. can be used. The SBR may be either a non-modified SBR or a modified SBR, but it is preferable to use at least one modified SBR from the viewpoint of the performance balance.

The modified SBR may be any SBR having a functional group that interacts with a filler such as silica. For example, at least one terminal of SBR is modified with a compound having a functional group (modifier). SBR (terminal-modified SBR having the above-mentioned functional group at the terminal), main-chain-modified SBR having the above-mentioned functional group at the main chain, main-chain terminal-modified SBR having the above-mentioned functional group at the main chain and the terminal (for example, in A hydroxyl group modified (coupled) with a polyfunctional compound having the above functional group and having at least one terminal modified with the above modifier with a main chain terminal modified SBR) or a polyfunctional compound having two or more epoxy groups in the molecule. And terminal-modified SBR into which an epoxy group has been introduced.

Examples of the functional groups include amino groups, amide groups, silyl groups, alkoxysilyl groups, isocyanate groups, imino groups, imidazole groups, urea groups, ether groups, carbonyl groups, oxycarbonyl groups, mercapto groups, sulfide groups, disulfides. 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, etc. . These functional groups may have a substituent. Among them, an amino group (preferably an amino group in which a hydrogen atom of the amino group is substituted with an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), an alkoxysilyl group ( An alkoxysilyl group having 1 to 6 carbon atoms is preferred.

（式中、Ｒ^１、Ｒ^２及びＲ^３は、同一又は異なって、アルキル基、アルコキシ基、シリルオキシ基、アセタール基、カルボキシル基（−ＣＯＯＨ）、メルカプト基（−ＳＨ）又はこれらの誘導体を表す。Ｒ^４及びＲ^５は、同一又は異なって、水素原子又はアルキル基を表す。Ｒ^４及びＲ^５は結合して窒素原子と共に環構造を形成してもよい。ｎは整数を表す。） As the modified SBR, SBR modified with a compound (modifier) represented by the following formula is particularly preferable.

Wherein R ¹ , R ² and R ³ are the same or different and represent an alkyl group, an alkoxy group, a silyloxy group, an acetal group, a carboxyl group (—COOH), a mercapto group (—SH) or a derivative thereof. R ⁴ and R ⁵ may be the same or different and each represents a hydrogen atom or an alkyl group, R ⁴ and R ⁵ may be bonded to form a ring structure with a nitrogen atom, and n represents an integer.)

As the modified SBR modified with the compound represented by the above formula (modifier), the polymerization terminal (active terminal) of the styrene butadiene rubber (S-SBR) of solution polymerization is the compound represented by the above formula. Modified SBR (modified SBR described in JP 2010-111753 A) is preferably used.

R ¹ , R ² and R ³ are preferably alkoxy groups (preferably having 1 to 8 carbon atoms, more preferably having 1 to 4 carbon atoms). R ⁴ and R ⁵ are preferably an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms). n is preferably 1 to 5, more preferably 2 to 4, and still more preferably 3. In the case of forming a ring structure with a nitrogen atom bonded to R ⁴ and R ^5, it is preferably a 4- to 8-membered ring. The alkoxy group also includes a cycloalkoxy group (such as cyclohexyloxy group) and an aryloxy group (such as phenoxy group and benzyloxy group).

Specific examples of the modifier include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltri Examples include methoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane. Of these, 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminopropyltriethoxysilane, and 3-diethylaminopropyltrimethoxysilane are preferable. These may be used alone or in combination of two or more.

As the modified SBR, modified SBR modified with the following compound (modifier) can also be suitably used. Examples of the modifier include polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether, glycerin triglycidyl ether, trimethylol ethane triglycidyl ether, trimethylol propane triglycidyl ether; and two or more of diglycidylated bisphenol A Polyglycidyl ethers of aromatic compounds having the following phenol groups; polyepoxy compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, polyepoxidized liquid polybutadiene; 4,4′-diglycidyl-diphenyl Epoxy group-containing tertiary amines such as methylamine and 4,4′-diglycidyl-dibenzylmethylamine; diglycidylaniline, N, N′-diglycidyl-4-glycidyloxyaniline, diglycidyl Luso toluidine, tetraglycidyl meta-xylene diamine, tetraglycidyl diaminodiphenylmethane, tetraglycidyl -p- phenylenediamine, diglycidyl aminomethyl cyclohexane, diglycidyl amino compounds such as tetraglycidyl-1,3-bisaminomethylcyclohexane;

Amino group-containing acid chlorides such as bis- (1-methylpropyl) carbamic acid chloride, 4-morpholine carbonyl chloride, 1-pyrrolidine carbonyl chloride, N, N-dimethylcarbamic acid chloride, N, N-diethylcarbamic acid chloride; 1 , 3-bis- (glycidyloxypropyl) -tetramethyldisiloxane, epoxy group-containing silane compounds such as (3-glycidyloxypropyl) -pentamethyldisiloxane;

(Trimethylsilyl) [3- (trimethoxysilyl) propyl] sulfide, (trimethylsilyl) [3- (triethoxysilyl) propyl] sulfide, (trimethylsilyl) [3- (tripropoxysilyl) propyl] sulfide, (trimethylsilyl) [3 -(Tributoxysilyl) propyl] sulfide, (trimethylsilyl) [3- (methyldimethoxysilyl) propyl] sulfide, (trimethylsilyl) [3- (methyldiethoxysilyl) propyl] sulfide, (trimethylsilyl) [3- (methyldioxy) Sulfide group-containing silane compounds such as propoxysilyl) propyl] sulfide, (trimethylsilyl) [3- (methyldibutoxysilyl) propyl] sulfide;

N-substituted aziridine compounds such as ethyleneimine and propyleneimine; alkoxysilanes such as methyltriethoxysilane; 4-N, N-dimethylaminobenzophenone, 4-N, N-di-t-butylaminobenzophenone, 4-N, N-diphenylaminobenzophenone, 4,4′-bis (dimethylamino) benzophenone, 4,4′-bis (diethylamino) benzophenone, 4,4′-bis (diphenylamino) benzophenone, N, N, N ′, N ′ A (thio) benzophenone compound having an amino group and / or a substituted amino group such as bis- (tetraethylamino) benzophenone; 4-N, N-dimethylaminobenzaldehyde, 4-N, N-diphenylaminobenzaldehyde, 4-N, Amino groups such as N-divinylaminobenzaldehyde And / or a benzaldehyde compound having a substituted amino group; N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, Nt-butyl-2-pyrrolidone, N-methyl-5 N-substituted pyrrolidones such as methyl-2-pyrrolidone N-substituted piperidones such as N-methyl-2-piperidone, N-vinyl-2-piperidone, N-phenyl-2-piperidone; N-methyl-ε-caprolactam; N such as N-phenyl-ε-caprolactam, N-methyl-ω-laurylactam, N-vinyl-ω-laurylactam, N-methyl-β-propiolactam, N-phenyl-β-propiolactam, etc. -Substituted lactams;

N, N-bis- (2,3-epoxypropoxy) -aniline, 4,4-methylene-bis- (N, N-glycidylaniline), tris- (2,3-epoxypropyl) -1,3,5 -Triazine-2,4,6-triones, N, N-diethylacetamide, N-methylmaleimide, N, N-diethylurea, 1,3-dimethylethyleneurea, 1,3-divinylethyleneurea, 1,3 -Diethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 4-N, N-dimethylaminoacetophene, 4-N, N-diethylaminoacetophenone, 1,3-bis (diphenyl) Amino) -2-propanone, 1,7-bis (methylethylamino) -4-heptanone, etc. can be mentioned. Of these, modified SBR modified with alkoxysilane is preferable.
In addition, modification | denaturation by the said compound (modifier) can be implemented by a well-known method.

As SBR, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Co., Ltd., Asahi Kasei Co., Ltd., Nippon Zeon Co., Ltd., etc. can be used, for example.

The BR is not particularly limited, and BR having a high cis content, BR containing a syndiotactic polybutadiene crystal, or the like can be used. The BR may be either a non-modified BR or a modified BR. Examples of the modified BR include a modified BR in which the above-described functional group is introduced. These may be used alone or in combination of two or more. Especially, it is suitable for the reason that abrasion resistance improves that the cis content of BR is 90 mass% or more (preferably 95 mass% or more). The cis content can be measured by infrared absorption spectrum analysis.

As BR, for example, products such as Ube Industries, JSR, Asahi Kasei, Nippon Zeon, and the like can be used.

The content of BR in 100% by mass of the rubber component is 20% by mass or more. By setting the lower limit or more, good wear resistance and low fuel consumption tend to be obtained. The content is preferably 40% by mass or less, more preferably 35% by mass or less, from the viewpoint of the performance balance.

Rubber components that can be used in addition to SBR and BR include diene systems such as isoprene rubber, acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), and styrene-isoprene-butadiene copolymer rubber (SIBR). Rubber. These diene rubbers may be used alone or in combination of two or more. Of these, isoprene-based rubber is preferred because it can further improve fuel economy and the like.

Examples of the isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. As the NR, for example, those commonly used in the tire industry such as SIR20, RSS # 3, TSR20 and the like can be used. As IR, it is not specifically limited, For example, IR2200 etc. can use what is common in tire industry. As modified NR, deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc., modified NR, epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. Examples of the modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used alone or in combination of two or more.

The content of isoprene-based rubber in 100% by mass of the rubber component is preferably 30% by mass or less, more preferably 20% by mass or less. By setting it to the upper limit or less, the SBR amount and the BR amount are secured, and the performance balance tends to be remarkably improved. Although a minimum is not specifically limited, When mix | blending, 3 mass% or more is preferable from a viewpoint of low fuel consumption, and 5 mass% or more is more preferable.

The rubber composition contains silica as a filler. Thereby, a reinforcing effect is obtained, wet grip performance and the like are improved, and the effect of the present invention is obtained satisfactorily. Examples of the silica include dry method silica (anhydrous silica), wet method silica (hydrous silica), and the like. Of these, wet-process silica is preferred because it has many silanol groups.

The content of silica is 50 parts by mass or more, preferably 55 parts by mass or more, and more preferably 60 parts by mass or more with respect to 100 parts by mass of the rubber component. By setting the lower limit or more, sufficient wet grip performance tends to be obtained. The content is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, and still more preferably 100 parts by mass or less. By making it below the upper limit, good dispersibility tends to be obtained.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 150 m ² / g or more, more preferably 160 m ² / g or more, and further preferably 165 m ² / g or more. By setting the lower limit or more, sufficient wet grip performance tends to be obtained. Further, N ₂ SA of silica is preferably 220 m ² / g or less, more preferably 200 m ² / g or less. By making it below the upper limit, good dispersibility tends to be obtained.
The _N 2 SA of silica is a value determined by the BET method in accordance with ASTM D3037-93.

Examples of silica that can be used include products such as Degussa, Rhodia, Tosoh Silica, Solvay Japan, and Tokuyama.

The rubber composition preferably contains a silane coupling agent together with silica.
The silane coupling agent is not particularly limited. For example, 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-trimethoxysilyl ester) 3) disulfide, bis (4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3 -Sulphides such as triethoxysilylpropyl methacrylate monosulfide, 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, Momentive NXT, NXT-Z, etc. mercapto, vinyltriethoxysilane, vinyl Vinyl type such as trimethoxysilane, amino type such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycid Glycidoxy such as cyclopropyltrimethoxysilane, nitro such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane, chloro such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane Etc. These may be used alone or in combination of two or more. Among these, a sulfide type and a mercapto type are preferable because the effects of the present invention can be obtained more favorably.

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

3 mass parts or more are preferable with respect to 100 mass parts of silica, and, as for content of a silane coupling agent, 5 mass parts or more are more preferable. There exists a tendency for the effect by addition to be acquired as it is 3 mass parts or more. The content is preferably 20 parts by mass or less, and more preferably 15 parts by mass or less. When the amount is 20 parts by mass or less, an effect commensurate with the blending amount is obtained, and good workability during kneading tends to be obtained.

The rubber composition preferably contains carbon black as a filler from the viewpoint of the performance balance. Although it does not specifically limit as carbon black, N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762 etc. are mentioned. These may be used alone or in combination of two or more.

The CTAB specific surface area (cetyltrimethylammonium bromide adsorption specific surface area) of carbon black is preferably 150 m ² / g or more, and more preferably 155 m ² / g or more, from the viewpoints of wet grip performance and wear resistance. Although an upper limit is not specifically limited, From a dispersible viewpoint of carbon black, 250 m < ² > / g or less is preferable and 200 m < ² > / g or less is more preferable.
The CTAB specific surface area is a value measured according to JIS K6217-3: 2001.

The iodine adsorption amount (IA) (mg / g) of carbon black is preferably 100 to 300 mg / g, more preferably 120 to 230 mg / g, still more preferably 140 to 190 mg / g. When the iodine adsorption amount (IA) is within the above range, an improvement effect such as wear resistance is suitably obtained, and the performance balance is remarkably improved.
In addition, IA is a value measured based on JISK6217-1: 2008.

The ratio of CTAB specific surface area to IA (mg / g) of carbon black (CTAB specific surface area / IA) is preferably 0.8 to 1.2 m ² / mg, more preferably 0.85, from the viewpoint of the performance balance. ˜1.15 m ² / mg, more preferably 0.9 to 1.1 m ² / mg.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 165 m ² / g or more, more preferably 170 m ² / g or more, and further preferably 175 m from the viewpoints of wet grip performance, wear resistance, and steering stability. ² / g or more. Although an upper limit is not specifically limited, From a dispersible viewpoint of carbon black, 250 m < ² > / g or less is preferable and 200 m < ² > / g or less is more preferable.
The N ₂ SA of carbon black can be measured according to JIS K 6217-2: 2001.

The content of carbon black is preferably 10 parts by mass or more, more preferably 13 parts by mass or more with respect to 100 parts by mass of the rubber component. When the amount is 10 parts by mass or more, sufficient reinforcement can be obtained, and good wear resistance tends to be obtained. Further, the content is preferably 40 parts by mass or less, more preferably 30 parts by mass or less. There exists a tendency for favorable rolling resistance to be acquired as it is 40 mass parts or less. The content of carbon black having the CTAB specific surface area, IA, and N ₂ SA is preferably in the same range.

Examples of carbon black include products such as Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Co., Ltd., Shin-Nikka Carbon Co., Ltd., Columbia Carbon Co., etc. Can be used.

You may mix | blend inorganic fillers and organic fillers other than a silica and carbon black with the said rubber composition.

Examples of the inorganic filler include talc, aluminum hydroxide, aluminum oxide, magnesium hydroxide, magnesium oxide, magnesium sulfate, titanium white, titanium black, calcium oxide, calcium hydroxide, aluminum magnesium oxide, clay, pyrophyllite, bentonite. , Aluminum silicate, magnesium silicate, calcium silicate, aluminum calcium silicate, magnesium silicate, silicon carbide, zirconium, zirconium oxide and the like. Examples of the organic filler include cellulose nanofibers. These may be used alone or in combination of two or more.

The total content of fillers (silica, carbon black, inorganic fillers other than these, organic fillers, etc.) is preferably 50 to 200 with respect to 100 parts by mass of the rubber component from the viewpoint of the performance balance. It is a mass part, More preferably, it is 60-150 mass part, More preferably, it is 70-120 mass part.

From the viewpoint of the performance balance, the rubber composition preferably contains C5, C9, C5 / C9 resin (resin in a solid state at room temperature (25 ° C.)) and the like, and C5 resin is particularly preferable.

Examples of the C5 resin include aliphatic petroleum resins obtained by (co) polymerizing a C5 fraction obtained by thermal decomposition of naphtha of petrochemical industry. C5 fraction includes olefinic hydrocarbons such as 1-pentene, 2-pentene, 2-methyl-1-butene, 2-methyl-1,3-butadiene, 1,2-pentadiene, 1,3-pentadiene, etc. Of diolefin hydrocarbons. Examples of the C9 resin include a solid polymer obtained by (co) polymerizing a C9 fraction using a Friedel-Crafts-type catalyst or the like. Specifically, a copolymer mainly containing indene, Examples thereof include a copolymer containing methylindene as a main component, a copolymer containing α-methylstyrene as a main component, and a copolymer containing vinyltoluene as a main component. The C5 resin is preferably aliphatic and the C9 resin is preferably alicyclic.

The softening point of the C5, C9, C5 / C9 resin is preferably 30 ° C. or higher, more preferably 60 ° C. or higher, and still more preferably 80 ° C. or higher. There exists a tendency for desired wet grip performance to be acquired as it is 30 ° C or more. The softening point is preferably 160 ° C. or lower, more preferably 130 ° C. or lower, and still more preferably 110 ° C. or lower. When the temperature is 160 ° C. or lower, the dispersibility of the resin becomes good, and the wet grip performance and the low fuel consumption tend to be improved.
In the present invention, the softening point is a temperature at which the sphere descends when the softening point specified in JIS K 6220-1: 2001 is measured with a ring and ball softening point measuring device.

The total content of the C5, C9 and C5 / C9 resins is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more with respect to 100 parts by mass of the rubber component. Moreover, the content is preferably 25 parts by mass or less, more preferably 20 parts by mass or less. When it is within the above range, there is a tendency that a good performance balance is obtained. The content of C5 resin, C9 resin, and C5 / C9 mixed resin alone is preferably in the same range.

You may mix | blend resin of a solid state with normal temperature (25 degreeC) other than C5, C9, and C5 / C9 resin to the said rubber composition. The resin is not particularly limited as long as it is widely used in the tire industry, and examples thereof include styrene resins, coumarone indene resins, terpene resins, pt-butylphenol acetylene resins, acrylic resins and the like.

The styrene resin is a polymer using a styrene monomer as a constituent monomer, and examples thereof include a polymer obtained by polymerizing a styrene monomer as a main component (50% by mass or more). Specifically, styrene monomers (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.) each independently polymerized, a copolymer obtained by copolymerizing two or more styrene monomers, and a styrene monomer And copolymers of other monomers that can be copolymerized therewith.

Examples of the other monomers include acrylonitriles such as acrylonitrile and methacrylonitrile, unsaturated carboxylic acids such as acrylics and methacrylic acid, unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate, chloroprene, and butadiene. Examples thereof include dienes such as isoprene, olefins such as 1-butene and 1-pentene, α, β-unsaturated carboxylic acids such as maleic anhydride or acid anhydrides thereof, and the like.

Among these, α-methylstyrene resins (α-methylstyrene homopolymer, copolymer of α-methylstyrene and styrene, etc.) are preferable from the viewpoint of the performance balance.

The softening point of the styrene resin is preferably 30 ° C. or higher, more preferably 60 ° C. or higher, and still more preferably 80 ° C. or higher. There exists a tendency for desired wet grip performance to be acquired as it is 30 ° C or more. The softening point is preferably 160 ° C. or lower, more preferably 130 ° C. or lower, and still more preferably 100 ° C. or lower. When the temperature is 160 ° C. or lower, the dispersibility of the resin becomes good, and the wet grip performance and the low fuel consumption tend to be improved.

The coumarone indene resin is a resin containing coumarone and indene as a monomer component constituting the resin skeleton (main chain). Examples of the monomer component contained in the skeleton other than coumarone and indene include styrene, α-methylstyrene, methylindene, and vinyltoluene.

Examples of the terpene resin include polyterpene, terpene phenol, and aromatic modified terpene resin.
Polyterpenes are resins obtained by polymerizing terpene compounds and their hydrogenated products. The terpene compound is a hydrocarbon represented by a composition of (C ₅ H ₈ ) _n and an oxygen-containing derivative thereof. Monoterpene (C ₁₀ H ₁₆ ), sesquiterpene (C ₁₅ H ₂₄ ), diterpene (C ₂₀ H ₃₂₎ ), Etc., which are classified into terpenes, for example, α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-ferrandrene, α-terpinene, γ-terpinene, terpinolene. 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol and the like.

Examples of polyterpenes include terpene resins such as α-pinene resins, β-pinene resins, limonene resins, dipentene resins, β-pinene / limonene resins, etc., which are made from the above-mentioned terpene compounds, as well as hydrogenated terpene resins. Additive terpene resins are also included.
Examples of the terpene phenol include a resin obtained by copolymerizing the terpene compound and the phenol compound, and a resin obtained by hydrogenating the resin. Specifically, the terpene compound, the phenol compound, and formalin are condensed. Resin. Examples of phenolic compounds include phenol, bisphenol A, cresol, and xylenol.
Examples of the aromatic modified terpene resin include a resin obtained by modifying a terpene resin with an aromatic compound, and a resin obtained by hydrogenating the resin. The aromatic compound is not particularly limited as long as it has an aromatic ring. For example, phenol compounds such as phenol, alkylphenol, alkoxyphenol, unsaturated hydrocarbon group-containing phenol; naphthol, alkylnaphthol, alkoxynaphthol, Examples thereof include naphthol compounds such as unsaturated hydrocarbon group-containing naphthol; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, and unsaturated hydrocarbon group-containing styrene; coumarone and indene.

Examples of the pt-butylphenol acetylene resin include a resin obtained by a condensation reaction of pt-butylphenol and acetylene.

The acrylic resin is not particularly limited, but a solventless acrylic resin can be suitably used from the viewpoint that a resin with few impurities and a sharp molecular weight distribution can be obtained.

Solvent-free acrylic resin is a high temperature continuous polymerization method (high temperature continuous mass polymerization method) (U.S. Pat. No. 4,414,370) without using as much as possible a polymerization initiator, a chain transfer agent, an organic solvent and the like as auxiliary materials. No., JP-A-59-6207, JP-B-5-58005, JP-A-1-313522, US Pat. No. 5,010,166, Toa Gosei Research Annual Report TREND2000 No. 3 p42 (Meth) acrylic resin (polymer) synthesized by the method described in -45 etc.). In the present invention, (meth) acryl means methacryl and acryl.

It is preferable that the acrylic resin does not substantially contain a polymerization initiator, a chain transfer agent, an organic solvent, or the like, which are auxiliary materials. The acrylic resin preferably has a relatively narrow composition distribution and molecular weight distribution obtained by continuous polymerization.

As described above, the acrylic resin is preferably one that does not substantially contain a polymerization initiator, a chain transfer agent, an organic solvent, or the like that is a secondary raw material, that is, has a high purity. The purity of the acrylic resin (ratio of the resin contained in the resin) is preferably 95% by mass or more, more preferably 97% by mass or more.

Examples of the monomer component constituting the acrylic resin include (meth) acrylic acid, (meth) acrylic acid esters (alkyl esters, aryl esters, aralkyl esters, etc.), (meth) acrylamides, and (meth) acrylamide derivatives. And (meth) acrylic acid derivatives.

Moreover, as monomer components constituting the acrylic resin, together with (meth) acrylic acid and (meth) acrylic acid derivatives, styrene, α-methylstyrene, vinyl toluene, vinyl naphthalene, divinyl benzene, trivinyl benzene, divinyl naphthalene, etc. Aromatic vinyl may be used.

The acrylic resin may be a resin composed only of a (meth) acrylic component, or may be a resin including components other than the (meth) acrylic component.
The acrylic resin may have a hydroxyl group, a carboxyl group, a silanol group, or the like.

Examples of resins such as C5, C9, C5 / C9 resins, styrene resins, and coumarone indene resins include Exxon Chemical Co., Ltd., Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yashara Chemical Co., Ltd., and Tosoh Corporation. Products such as Co., Ltd., Rutgers Chemicals, BASF, Arizona Chemical, Nikkaku Chemical Co., Ltd., Nippon Shokubai Co., Ltd., JX Energy Co., Ltd., Arakawa Chemical Co., Ltd., Taoka Chemical Co., Ltd. Can be used.

In the rubber composition, the total content of the resin (resin in a solid state at room temperature (25 ° C.) such as the C5, C9, C5 / C9 resin, and styrene resin) is preferably based on 100 parts by mass of the rubber component. Is 0.5 parts by mass or more, more preferably 1 part by mass or more. The content is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and still more preferably 20 parts by mass or less. When it is within the above range, there is a tendency that a good performance balance is obtained.

The rubber composition preferably contains oil as a softening agent.
Examples of the oil include process oil, vegetable oil and fat, or a mixture thereof. As the process oil, for example, a paraffin process oil, an aroma process oil, a naphthenic process oil, or the like can be used. As vegetable oils and fats, castor oil, cottonseed oil, sesame oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut hot water, rosin, pine oil, pineapple, tall oil, corn oil, rice bran oil, beet flower oil, sesame oil, Examples include olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. These may be used alone or in combination of two or more. Among these, naphthenic process oils are preferable because the effects of the present invention can be obtained better.

Examples of the oil include Idemitsu Kosan Co., Ltd., Sankyo Oil Chemical Co., Ltd., Japan Energy Co., Ltd., Orisoi Co., Ltd., H & R Co., Toyokuni Oil Co., Ltd., Showa Shell Sekiyu Co., Ltd., Fuji Kosan Co., Ltd. Etc. can be used.

The oil content is preferably 5 parts by mass or more, more preferably 10 parts by mass or more with respect to 100 parts by mass of the rubber component. Further, the content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less. If it is within the above numerical range, the performance balance tends to be remarkably improved.
The oil content includes the amount of oil contained in rubber (oil-extended rubber).

You may mix | blend a liquid diene type polymer with the said rubber composition as a softening agent.
The liquid diene polymer is a diene polymer in a liquid state at normal temperature (25 ° C.). The liquid diene polymer preferably has a polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) of 1.0 × 10 ^{3 to} 2.0 × 10 ^5. It is more preferable that it is * 10 < ³ > -1.5 * 10 < ⁴ >. Examples of the liquid diene polymer include a liquid styrene butadiene copolymer (liquid SBR), a liquid butadiene polymer (liquid BR), a liquid isoprene polymer (liquid IR), a liquid styrene isoprene copolymer (liquid SIR), and the like. It is done.

In the rubber composition, the total content of softening agents (hydrocarbons, resins, etc. in a liquid state at normal temperature (25 ° C.) such as oil and liquid diene polymerization) is 100 masses of rubber component from the viewpoint of the balance of performance. Preferably it is 5-50 mass parts with respect to a part, More preferably, it is 10-30 mass parts.

The rubber composition preferably contains a wax.
The wax is not particularly limited, and examples thereof include petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as plant waxes and animal waxes; synthetic waxes such as polymers such as ethylene and propylene. These may be used alone or in combination of two or more. Of these, petroleum wax is preferable, and paraffin wax is more preferable.

The content of the wax is preferably 1 to 20 parts by mass, more preferably 1.5 to 10 parts by mass with respect to 100 parts by mass of the rubber component from the viewpoint of the performance balance.

For example, products such as Ouchi Shinsei Chemical Co., Ltd., Nippon Seiwa Co., Ltd., Seiko Chemical Co., Ltd. can be used as the wax.

The rubber composition preferably contains an anti-aging agent.
Examples of the antiaging agent include naphthylamine type antiaging agents such as phenyl-α-naphthylamine; diphenylamine type antiaging agents such as octylated diphenylamine and 4,4′-bis (α, α′-dimethylbenzyl) diphenylamine; N -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 2,2,4-trimethyl-1,2-dihydroquinoline polymer; 2,6-di-t-butyl-4-methylphenol; Monophenolic antioxidants such as styrenated phenol; tetrakis- [methylene-3- (3 ', 5'-di-t-butyl- '- hydroxyphenyl) propionate] bis methane, tris, and the like polyphenolic antioxidants. These may be used alone or in combination of two or more. Of these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferable, and N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, 2,2,4-trimethyl-1 More preferred is a polymer of 1,2-dihydroquinoline.

The content of the anti-aging agent is preferably 1 to 10 parts by mass or more, more preferably 2 to 7 parts by mass or more with respect to 100 parts by mass of the rubber component from the viewpoint of the performance balance.

As the anti-aging agent, for example, products such as Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinsei Chemical Co., Ltd., and Flexis Co. can be used.

The rubber composition preferably contains stearic acid. The content of stearic acid is preferably 0.5 to 10 parts by mass or more, more preferably 1 to 5 parts by mass or more with respect to 100 parts by mass of the rubber component from the viewpoint of the performance balance.

As stearic acid, conventionally known ones can be used. For example, products such as NOF Corporation, NOF, Kao Corporation, Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd. can be used. .

The rubber composition preferably contains zinc oxide. The content of zinc oxide is preferably 0.5 to 10 parts by mass or more, more preferably 1 to 5 parts by mass or more with respect to 100 parts by mass of the rubber component, from the viewpoint of the performance balance.

In addition, as a zinc oxide, a conventionally well-known thing can be used, for example, Mitsui Metal Mining Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Shodo Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. Can be used.

The rubber composition preferably contains sulfur.
The content of sulfur is preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass, and further preferably 1 to 3 parts by mass with respect to 100 parts by mass of the rubber component from the viewpoint of the performance balance. .

Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur that are generally used in the rubber industry. These may be used alone or in combination of two or more.

In addition, as sulfur, for example, products such as Tsurumi Chemical Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexis Co., Nihon Kibushi Kogyo Co., Ltd., Hosoi Chemical Co., Ltd. can be used. .

The rubber composition preferably contains a vulcanization accelerator.
The content of the vulcanization accelerator is preferably 1 to 10 parts by mass, more preferably 3 to 7 parts by mass with respect to 100 parts by mass of the rubber component from the viewpoint of the performance balance.

Examples of the vulcanization accelerator include thiazole vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, N-cyclohexyl-2-benzothiazylsulfenamide; tetramethylthiuram disulfide (TMTD ), Tetrabenzylthiuram 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. Sulfena De-based vulcanization accelerator; diphenylguanidine, it may be mentioned di-ortho-tolyl guanidine, guanidine-based vulcanization accelerators such as ortho tri ruby guanidine. These may be used alone or in combination of two or more. Of these, sulfenamide vulcanization accelerators and guanidine vulcanization accelerators are preferable from the viewpoint of the performance balance.

You may mix | blend an organic crosslinking agent with the said rubber composition.
The organic crosslinking agent is not particularly limited, and examples thereof include maleimide compounds, alkylphenol / sulfur chloride condensates, organic peroxides, and amine organic sulfides. These may be used alone or in combination of two or more, and may be used in combination with sulfur. In addition, an organic crosslinking agent is mix | blended at 10 mass parts or less with respect to 100 mass parts of rubber components, for example.

The rubber composition of the present invention is produced by a general method. That is, it can be produced by a method of kneading the above components with a Banbury mixer, a kneader, an open roll or the like and then vulcanizing.

As the kneading conditions, in the base kneading step in which additives other than the vulcanizing agent and the vulcanization accelerator are kneaded, the kneading temperature is usually 50 to 200 ° C., preferably 80 to 190 ° C., and the kneading time is usually 30. Second to 30 minutes, preferably 1 to 30 minutes. In the final kneading step of kneading the vulcanizing agent and the vulcanization accelerator, the kneading temperature is usually 100 ° C. or lower, preferably room temperature to 80 ° C. Further, 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 usually 120 to 200 ° C, preferably 140 to 180 ° C.

The rubber composition of the present invention is suitably used for treads (cap treads), but members other than treads, for example, sidewalls, base treads, under treads, clinch apex, bead apex, breaker cushion rubber, carcass cord You may use for the rubber | gum for coating | cover, an insulation, a chafer, an inner liner, etc., and the side reinforcement layer of a run flat tire.

The pneumatic tire of the present invention is produced by a usual method using the rubber composition.
That is, the rubber composition containing the above components is extruded in accordance with the shape of each tire member such as a tread at an unvulcanized stage, and is molded together with the other tire members by a normal method on a tire molding machine. By doing so, an unvulcanized tire is formed. The unvulcanized tire is heated and pressurized in a vulcanizer to obtain a tire.

The present invention will be specifically described based on examples, but the present invention is not limited to these examples.
The various chemicals used in the examples are described below.
NR: TSR20
SBR1 (modified): modified SBR synthesized in Production Example 1
SBR2 (non-modified): styrene content 35% by mass, vinyl content 35% by mass, weight average molecular weight Mw 1.05 million BR: non-modified BR (cis content 97% by mass)
Carbon black 1: CTAB 160 m ² / g, N ₂ SA 179 m ² / g, IA 166 mg / g
Carbon black 2: CTAB 111 m ² / g, N ₂ SA 111 m ² / g
Silica: N ₂ SA 175 m ² / g
Silane coupling agent: bis (3-triethoxysilylpropyl) disulfide oil: naphthenic process oil C5 resin: softening point 97-103 ° C
Wax: Paraffin wax anti-aging agent 1: N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine anti-aging agent 2: Poly (2,2,4-trimethyl-1,2-dihydroquinoline )
Stearic acid: Stearic acid “椿” manufactured by NOF Corporation
Zinc oxide: Zinc Hua No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powdered sulfur vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd. 1: N-tert-butyl-2-benzothiazolylsulfenamide vulcanization accelerator 2: Diphenylguanidine

(Production Example 1)
Under a nitrogen atmosphere, 3-dimethylaminopropyltrimethoxysilane was placed in a 100 ml volumetric flask, and anhydrous hexane was further added to prepare a terminal modifier.
N-Hexane, styrene, butadiene, and tetramethylethylenediamine were added to a pressure vessel sufficiently substituted with nitrogen, and the temperature was raised to 40 ° C. Next, after adding butyl lithium, the temperature was raised to 50 ° C. and stirred. Next, a silicon tetrachloride / hexane solution was added and stirred. Next, the terminal modifier was added and stirred. After adding methanol in which 2,6-tert-butyl-p-cresol was dissolved to the reaction solution, the reaction solution was put into a stainless steel container containing methanol to collect aggregates. The obtained aggregate was dried under reduced pressure for 24 hours to obtain modified SBR1. The obtained modified SBR1 had a styrene content of 25% by mass, a vinyl content of 60% by mass, and a weight average molecular weight Mw of 150,000.

<Analysis of SBR>
In addition, the analysis of SBR1-2 was performed with the following method.
(Measurement of weight average molecular weight Mw)
The weight average molecular weight Mw of the polymer is measured by gel permeation chromatograph (GPC) (GPC-8000 series, manufactured by Tosoh Corp., detector: differential refractometer, column: TSKGEL SUPERMALTPORE HZ-M, manufactured by Tosoh Corp.). It calculated | required as a standard polystyrene conversion value based on the value.

(Structural identification)
The structural identification of SBR (measurement of styrene content and vinyl content) was performed using a JNM-ECA series apparatus manufactured by JEOL Ltd. The measurement was performed after drying under reduced pressure, by dissolving 0.1 g of the polymer in 15 ml of toluene, slowly pouring it into 30 ml of methanol and reprecipitating it.

<Examples and Comparative Examples>
In accordance with the formulation shown in Table 1, materials other than sulfur and a vulcanization accelerator were kneaded for 5 minutes at 150 ° C. using a 1.7 L Banbury mixer manufactured by Kobe Steel, Ltd. Obtained. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and kneaded for 5 minutes under the condition of 80 ° C. using an open roll to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition is formed into a tread shape and bonded together with other tire members to form an unvulcanized tire, press vulcanized at 170 ° C. for 10 minutes, and a test tire ( Size: 195 / 65R15). The obtained test tire was used for evaluation, and the results are shown in Table 1.

(Low fuel consumption)
Using a rolling resistance tester, the rolling resistance when a test tire is run at a rim (15 × 6JJ), internal pressure (230 kPa), load (3.43 kN), speed (80 km / h) is measured and compared. Example 1 is shown as an index when the index is 100 (low fuel consumption index). A larger index indicates better fuel efficiency.

(Wet grip performance)
Each test tire was mounted on all wheels of a vehicle (domestic FF2000cc), the braking distance from the initial speed of 100 km / h was obtained on the wet asphalt road surface, and displayed as an index when Comparative Example 1 was set to 100 (wet Grip performance index). The larger the index, the shorter the braking distance and the better the wet grip performance.

(Abrasion resistance)
Each test tire was mounted on a domestic FF vehicle, the groove depth of the tire tread portion after a mileage of 8000 km was measured, and the mileage when the tire groove depth decreased by 1 mm was calculated. Expressed as an index of time (wear resistance index). The larger the index, the longer the travel distance when the tire groove depth is reduced by 1 mm, and the better the wear resistance.

From Table 1, the examples containing SBR having a predetermined average molecular weight and an average vinyl amount, BR, and silica in a predetermined ratio do not satisfy the formulation using SBR that does not satisfy the average molecular weight and vinyl amount and the silica amount. Compared with the comparative example, a good performance balance of low fuel consumption, wet grip performance and wear resistance was obtained.

Claims (5)

Including styrene butadiene rubber, butadiene rubber and silica,
The content of the styrene butadiene rubber in 100% by mass of the rubber component is 40% by mass or more, the content of the butadiene rubber is 20% by mass or more,
The content of the silica with respect to 100 parts by mass of the rubber component is 50 parts by mass or more,
The styrene-butadiene rubber is a tire rubber composition having an average molecular weight of 300,000 or less and an average vinyl content of 40% by mass or more. The tire rubber composition according to claim 1, wherein the silica has a nitrogen adsorption specific surface area of 150 m ² / g or more. Claim 1 or 2 tire rubber composition according content of CTAB specific surface 150 meters ² / g or more carbon black is 10 to 40 parts by weight with respect to 100 parts by mass of the rubber component. The rubber composition for a tire according to any one of claims 1 to 3, wherein the content of the C5 resin with respect to 100 parts by mass of the rubber component is 1 part by mass or more. The pneumatic tire produced using the rubber composition in any one of Claims 1-4.