JP7363102B2 - pneumatic tires - Google Patents

Description

The present invention relates to pneumatic tires.

Since pneumatic tires (especially tires for heavy loads) are required to have excellent durability and wear resistance, various improvement methods have been studied so far (see, for example, Patent Document 1). However, in recent years, further improvements in these are required.

Japanese Patent Application Publication No. 2011-140532

An object of the present invention is to solve the above problems and provide a pneumatic tire with excellent durability and wear resistance.

The present invention includes a tread portion including a cap tread and a base tread, and a cap rubber composition constituting the cap tread includes a rubber component containing isoprene rubber, styrene-butadiene rubber, and butadiene rubber, and a cetyltrimethylammonium bromide specific surface area. is 130 m ² /g or more, and the base rubber composition constituting the base tread comprises a rubber component having an isoprene rubber content of 90% by mass or more, a C5 resin, and a cetyl rubber composition. The present invention relates to a pneumatic tire containing trimethylammonium bromide and carbon black having a specific surface area of 30 m ² /g or more.

The pneumatic tire preferably satisfies the following formula (A).
(A) α-β≧10
α: Total content of filler in the cap rubber composition [parts by mass]
β: Total content of filler in the base rubber composition [parts by mass]

In the cap rubber composition, the content of isoprene rubber in 100% by mass of the rubber component is preferably 40% by mass or more.

In the cap rubber composition, the content of silica is preferably 5 parts by mass or more based on 100 parts by mass of the rubber component.

It is preferable that the cap rubber composition contains a resin.

It is preferable that the pneumatic tire is a heavy load tire.

According to the present invention, a cap rubber composition comprising a tread portion including a cap tread and a base tread, and a cap rubber composition constituting the cap tread includes a rubber component containing an isoprene rubber, a styrene-butadiene rubber, and a butadiene rubber, and a cetyltrimethylammonium bromide ratio. The base rubber composition constituting the base tread contains carbon black having a surface area of 130 m ² /g or more, a rubber component having an isoprene rubber content of 90% by mass or more, a C5 resin, and cetyl. Since it is a pneumatic tire containing trimethylammonium bromide and carbon black having a specific surface area of 30 m ² /g or more, excellent durability and wear resistance can be obtained.

The pneumatic tire of the present invention includes a tread portion including a cap tread and a base tread, and the cap rubber composition constituting the cap tread includes a rubber component containing isoprene rubber, styrene-butadiene rubber, and butadiene rubber, and cetyltrimethylammonium. The base rubber composition constituting the base tread, which contains carbon black having a bromide specific surface area of 130 m ² /g or more, contains a rubber component having an isoprene rubber content of 90% by mass or more, and a C5 resin. , cetyltrimethylammonium bromide carbon black having a specific surface area of 30 m ² /g or more.

The above-mentioned pneumatic tire provides the above-mentioned effects, which are presumed to be due to the following effects.
In the above pneumatic tire, the cap rubber composition contains a specific rubber component and carbon black, and the base rubber composition contains a specific rubber component, carbon black, and a C5 resin. The co-crosslinkability with the base rubber composition is improved, and the adhesive strength between these members is improved. It is believed that this significantly improves durability and abrasion resistance.

Moreover, according to the pneumatic tire, the overall performance of durability, abrasion resistance, wet grip performance, and chipping resistance also tends to be improved.

In the above pneumatic tire, the rubber component is a component that contributes to crosslinking, generally has a weight average molecular weight (Mw) of 10,000 or more, and is solid at normal temperature and pressure.
Mw is a standard value based on the measured value by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation). It can be determined by polystyrene conversion.

<Cap rubber composition>
The cap rubber composition constituting the cap tread in the tread portion of the pneumatic tire will be described below.

The cap rubber composition contains isoprene rubber.
As the isoprene rubber, isoprene rubber (IR), natural rubber (NR), epoxidized natural rubber (ENR), etc. can be used. Modified NR such as deproteinized natural rubber (DPNR) and high purity natural rubber (UPNR) can also be used. These may be used alone or in combination of two or more.

The content of isoprene rubber in 100% by mass of the rubber component is preferably 40% by mass or more, more preferably 50% by mass or more, and preferably 70% by mass or less, more preferably 60% by mass or less. . Within the above range, the above-mentioned overall performance tends to be good.

The cap rubber composition contains SBR.
The 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. SBR may be either non-denatured SBR or modified SBR.

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

Examples of the above 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, and disulfide groups. 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. . Note that these functional groups may have a substituent. Among these, an 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), 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 suitable.

(In the formula, 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 are the same or different and represent a hydrogen atom or an alkyl group. R ⁴ and R ⁵ may be combined to form a ring structure with a nitrogen atom. n represents an integer.)

Among the modified SBRs modified with the compound (modifier) represented by the above formula, the polymerization end (active end) of solution polymerized styrene butadiene rubber (S-SBR) is modified by the compound represented by the above formula. Modified SBR (such as the modified SBR described in JP-A No. 2010-111753) is preferably used.

An alkoxy group is suitable for R ¹ , R ² and R ³ (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms). As R ⁴ and R ⁵ , an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms) is suitable. n is preferably 1 to 5, more preferably 2 to 4, and still more preferably 3. Furthermore, when R ⁴ and R ⁵ combine to form a ring structure together with a nitrogen atom, it is preferably a 4- to 8-membered ring. Note that the alkoxy group also includes a cycloalkoxy group (cyclohexyloxy group, etc.) and an aryloxy group (phenoxy group, benzyloxy group, etc.).

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

As the modified SBR, modified SBR modified with the following compounds (modifiers) can also be suitably used. Examples of modifiers include polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether, glycerin triglycidyl ether, trimethylolethane triglycidyl ether, and trimethylolpropane triglycidyl ether; two or more of diglycidylated bisphenol A, etc. Polyglycidyl ethers of aromatic compounds having phenol groups; polyepoxy compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxidized liquid polybutadiene; 4,4'-diglycidyl-diphenyl Epoxy group-containing tertiary amines such as methylamine, 4,4'-diglycidyl-dibenzylmethylamine; diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline, diglycidyl orthotoluidine, tetraglycidyl metaxylene diamine , diglycidylamino compounds such as tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, tetraglycidyl-1,3-bisaminomethylcyclohexane;

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

(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-(methyldimethoxysilyl)propyl]sulfide sulfide group-containing silane compounds such as propoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(methyldibutoxysilyl)propyl] sulfide;

N-substituted aziridine compounds such as ethyleneimine and propyleneimine; methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxy Silane, alkoxysilanes such as N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethyltriethoxysilane; 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, (thio)benzophenone compounds having an amino group and/or substituted amino group such as N,N,N',N'-bis-(tetraethylamino)benzophenone; 4-N,N-dimethylaminobenzaldehyde, 4- Benzaldehyde compounds having an amino group and/or substituted amino group such as N,N-diphenylaminobenzaldehyde, 4-N,N-divinylaminobenzaldehyde; N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N- N-substituted pyrrolidone such as phenyl-2-pyrrolidone, N-t-butyl-2-pyrrolidone, N-methyl-5-methyl-2-pyrrolidone, N-methyl-2-piperidone, N-vinyl-2-piperidone, N -N-substituted piperidones such as phenyl-2-piperidone; N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-laurirolactam, N-vinyl-ω-laurirolactam, N- - N-substituted lactams such as methyl-β-propiolactam and N-phenyl-β-propiolactam;

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) Examples include amino)-2-propanone, 1,7-bis(methylethylamino)-4-heptanone, and the like. Among these, modified SBR modified with alkoxysilane is preferred.
Note that modification with the above compound (modifier) can be carried out by a known method.

The amount of styrene in SBR is preferably 10% by mass or more, more preferably 20% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. Within the above range, the above-mentioned overall performance tends to be good.
Note that the amount of styrene can be measured by the method described in Examples below.

The amount of vinyl in SBR is preferably 5% by mass or more, more preferably 15% by mass or more, and preferably 60% by mass or less, more preferably 45% by mass or less. Within the above range, the above-mentioned overall performance tends to be good.
The vinyl content (1,2-bonded butadiene unit content) can be measured by the method described in Examples below.

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

The content of SBR in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more, and preferably 40% by mass or less, more preferably 30% by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

The above rubber composition contains BR.
The BR is not particularly limited, and BR with a high cis content, BR with a low cis content, BR containing syndiotactic polybutadiene crystals, etc. can be used. The BR may be either unmodified BR or modified BR, and examples of the modified BR include modified BR into which the above-mentioned functional groups have been introduced. These may be used alone or in combination of two or more. The cis content of BR is preferably 90% by mass or more.
Note that the cis content can be measured by infrared absorption spectroscopy.

As the BR, for example, products manufactured by Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Corporation, etc. can be used.

The content of BR in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more, and preferably 40% by mass or less, more preferably 30% by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

Rubber components that can be used in addition to isoprene rubber, SBR, and BR include dienes such as acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), and styrene-isoprene-butadiene copolymer rubber (SIBR). Examples include rubber. These diene rubbers may be used alone or in combination of two or more.

The cap rubber composition contains carbon black (hereinafter also referred to as carbon black A) having a cetyltrimethylammonium bromide (CTAB) specific surface area of 130 m ² /g or more.
Carbon black A is not particularly limited, and examples include N134 and N110. These may be used alone or in combination of two or more.

The CTAB specific surface area of carbon black A may be at least 130 m ² /g, preferably at least 140 m ² /g, more preferably at least 145 m ² /g, even more preferably at least 150 m ² /g, and Preferably it is 250 m ² /g or less, more preferably 200 m ² /g or less. Within the above range, the above-mentioned overall performance tends to be good.
Note that the CTAB specific surface area of carbon black is a value measured in accordance with JIS K6217-3:2001.

The content of carbon black A 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 15 parts by mass or less, based on 100 parts by mass of the rubber component. It is. Within the above range, the above-mentioned overall performance tends to be good.

The cap rubber composition may contain other carbon black (carbon black with a CTAB specific surface area of less than 130 m ² /g) in addition to carbon black A.
Other carbon blacks are not particularly limited, and include N220, N660, and the like. These may be used alone or in combination of two or more.

The CTAB specific surface area of the other carbon black is preferably 120 m ² /g or less, more preferably 115 m ² /g or less, and preferably 50 m ² /g or more, more preferably 80 m ² /g or more, even more preferably is 100 m ² /g or more. Within the above range, the above-mentioned overall performance tends to be good.

When containing other carbon black, the content of the other carbon black is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and preferably 30 parts by mass, based on 100 parts by mass of the rubber component. parts, more preferably 15 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

Carbon black A and other carbon blacks include, for example, Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Corporation, Nippon Kabon Co., Ltd. Products such as Columbia Carbon Co., Ltd. can be used.

The cap rubber composition may contain silica.
Examples of silica include dry process silica (anhydrous silicic acid), wet process silica (hydrous silicic acid), and wet process silica is preferable because it has a large number of 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 100 m ² /g or more, more preferably 150 m ² /g or more, and preferably 200 m ² /g or less, more preferably 180 m ² /g or less. It is. Within the above range, the above-mentioned overall performance tends to be good.
Note that the nitrogen adsorption specific surface area of silica is a value measured by the BET method according to ASTM D3037-81.

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

When containing silica, the content of silica per 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, and preferably 60 parts by mass or less, more preferably 45 parts by mass. It is as follows. Within the above range, the above-mentioned overall performance tends to be good.

The cap rubber composition may contain a silane coupling agent together with silica.
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-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyltetrasulfide, 3- Sulfide types such as triethoxysilylpropyl methacrylate monosulfide, mercapto types such as 3-mercaptopropyltrimethoxysilane and 2-mercaptoethyltriethoxysilane, vinyl types such as vinyltriethoxysilane and vinyltrimethoxysilane, 3-aminopropyl Amino type such as triethoxysilane, 3-aminopropyltrimethoxysilane, glycidoxy type such as γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, 3-nitropropyltrimethoxysilane, 3- Examples include nitro types such as nitropropyltriethoxysilane, and chloro types such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. These may be used alone or in combination of two or more. Among these, the mercapto type is more preferable because the above-mentioned overall performance tends to be good.

As the mercapto-based silane coupling agent, in addition to compounds having a mercapto group, compounds having a structure in which a mercapto group is protected by a protecting group (for example, a compound represented by the following formula (S1)) can also be used. .

（式中、Ｒ^１００１は－Ｃｌ、－Ｂｒ、－ＯＲ^１００６、－Ｏ（Ｏ＝）ＣＲ^１００６、－ＯＮ＝ＣＲ^１００６Ｒ^１００７、－ＮＲ^１００６Ｒ^１００７及び－（ＯＳｉＲ^１００６Ｒ^１００７）_ｈ（ＯＳｉＲ^１００６Ｒ^１００７Ｒ^１００８）から選択される一価の基（Ｒ^１００６、Ｒ^１００７及びＲ^１００８は同一でも異なっていても良く、各々水素原子又は炭素数１～１８の一価の炭化水素基であり、ｈは平均値が１～４である。）であり、Ｒ^１００２はＲ^１００１、水素原子又は炭素数１～１８の一価の炭化水素基、Ｒ^１００３は－［Ｏ（Ｒ^１００９Ｏ）_ｊ］－基（Ｒ^１００９は炭素数１～１８のアルキレン基、ｊは１～４の整数である。）、Ｒ^１００４は炭素数１～１８の二価の炭化水素基、Ｒ^１００５は炭素数１～１８の一価の炭化水素基を示し、ｘ、ｙ及びｚは、ｘ＋ｙ＋２ｚ＝３、０≦ｘ≦３、０≦ｙ≦２、０≦ｚ≦１の関係を満たす数である。）

（式中、ｖは０以上の整数、ｗは１以上の整数である。Ｒ^１１は水素、ハロゲン、分岐若しくは非分岐の炭素数１～３０のアルキル基、分岐若しくは非分岐の炭素数２～３０のアルケニル基、分岐若しくは非分岐の炭素数２～３０のアルキニル基、又は該アルキル基の末端の水素が水酸基若しくはカルボキシル基で置換されたものを示す。Ｒ^１２は分岐若しくは非分岐の炭素数１～３０のアルキレン基、分岐若しくは非分岐の炭素数２～３０のアルケニレン基、又は分岐若しくは非分岐の炭素数２～３０のアルキニレン基を示す。Ｒ^１１とＲ^１２とで環構造を形成してもよい。） Particularly suitable mercapto-based silane coupling agents include a silane coupling agent represented by the following formula (S1), and a combination of a bonding unit A represented by the following formula (I) and a bonding unit B represented by the following formula (II). Examples include silane coupling agents containing silane coupling agents.

(In the formula, R ¹⁰⁰¹ is -Cl, -Br, -OR ¹⁰⁰⁶ , -O(O=)CR ¹⁰⁰⁶ , -ON=CR ¹⁰⁰⁶ R ¹⁰⁰⁷ , -NR ¹⁰⁰⁶ R ¹⁰⁰⁷ and -(OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ ) _h (OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ R ¹⁰⁰⁸ ) (R ¹⁰⁰⁶ , R ¹⁰⁰⁷ and R ¹⁰⁰⁸ may be the same or different, each being a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms; , h has an average value of 1 to 4), R ¹⁰⁰² is R ¹⁰⁰¹ , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, and R ¹⁰⁰³ is -[O(R ¹⁰⁰⁹ O) _j ]- group (R ¹⁰⁰⁹ is an alkylene group having 1 to 18 carbon atoms, j is an integer of 1 to 4), R ¹⁰⁰⁴ is a divalent hydrocarbon group having 1 to 18 carbon atoms, R 1005 is an alkylene group having 1 to 18 carbon atoms, and R ¹⁰⁰⁵ is a divalent hydrocarbon group having 1 to 18 carbon atoms. ~18 monovalent hydrocarbon groups, x, y, and z are numbers that satisfy the following relationships: x+y+2z=3, 0≦x≦3, 0≦y≦2, 0≦z≦1.)

⁽ In the formula, v is an integer of 0 or more, and w is an integer of 1 or more. 30 alkenyl group, a branched or unbranched alkynyl group having 2 to 30 carbon atoms, or one in which the terminal hydrogen of the alkyl group is substituted with a hydroxyl group or carboxyl group.R ¹² is the branched or unbranched carbon number It represents an alkylene group having 1 to 30 carbon atoms, a branched or unbranched alkenylene group having 2 to 30 carbon atoms, or a branched or unbranched alkynylene group having 2 to 30 carbon atoms.R ¹¹ and R ¹² form a ring structure. )

In formula (S1), R ¹⁰⁰⁵ , R ¹⁰⁰⁶ , R ¹⁰⁰⁷ and R ¹⁰⁰⁸ each independently represent a linear, cyclic or branched alkyl group having 1 to 18 carbon atoms, an alkenyl group, an aryl group and an aralkyl group. Preferably, it is a group selected from the group consisting of: Further, when R ¹⁰⁰² is a monovalent hydrocarbon group having 1 to 18 carbon atoms, it is selected from the group consisting of a linear, cyclic or branched alkyl group, alkenyl group, aryl group and aralkyl group. It is preferable that it is a group. R ¹⁰⁰⁹ is preferably a linear, cyclic or branched alkylene group, particularly preferably a linear one. R ¹⁰⁰⁴ is, for example, an alkylene group having 1 to 18 carbon atoms, an alkenylene group having 2 to 18 carbon atoms, a cycloalkylene group having 5 to 18 carbon atoms, a cycloalkylalkylene group having 6 to 18 carbon atoms, or an arylene group having 6 to 18 carbon atoms. and an aralkylene group having 7 to 18 carbon atoms. Alkylene groups and alkenylene groups may be linear or branched, and cycloalkylene groups, cycloalkylalkylene groups, arylene groups, and aralkylene groups have a functional group such as a lower alkyl group on the ring. You may do so. R ¹⁰⁰⁴ is preferably an alkylene group having 1 to 6 carbon atoms, particularly a linear alkylene group such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, or a hexamethylene group.

Specific examples of R ¹⁰⁰² , R ¹⁰⁰⁵ , R ¹⁰⁰⁶ , R ¹⁰⁰⁷ and R ¹⁰⁰⁸ in formula (S1) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group. group, tert-butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, cyclopentyl group, cyclohexyl group, vinyl group, propenyl group, allyl group, hexenyl group, octenyl group, cyclopentenyl group, cyclo Examples include hexenyl group, phenyl group, tolyl group, xylyl group, naphthyl group, benzyl group, phenethyl group, and naphthylmethyl group.
As an example of R ¹⁰⁰⁹ in formula (S1), linear alkylene groups include methylene group, ethylene group, n-propylene group, n-butylene group, hexylene group, etc., and branched alkylene groups include: Examples include isopropylene group, isobutylene group, and 2-methylpropylene group.

Specific examples of the silane coupling agent represented by formula (S1) include 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltriethoxysilane, and 3-hexanoylthiopropyltriethoxysilane. lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane, 3-hexanoyl ruthiopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2-octanoylthio Examples include ethyltrimethoxysilane, 2-decanoylthioethyltrimethoxysilane, and 2-lauroylthioethyltrimethoxysilane. These may be used alone or in combination of two or more. Among them, 3-octanoylthiopropyltriethoxysilane is particularly preferred.

In the silane coupling agent containing bonding unit A represented by formula (I) and bonding unit B represented by formula (II), the content of bonding unit A is preferably 30 mol% or more, more preferably 50 mol%. % or more, preferably 99 mol% or less, more preferably 90 mol% or less. Further, the content of bonding unit B is preferably 1 mol% or more, more preferably 5 mol% or more, even more preferably 10 mol% or more, preferably 70 mol% or less, more preferably 65 mol% or less, More preferably, it is 55 mol% or less. Further, the total content of bonding units A and B is preferably 95 mol% or more, more preferably 98 mol% or more, particularly preferably 100 mol%.
Note that the content of the bonding units A and B includes the case where the bonding units A and B are located at the ends of the silane coupling agent. When the bonding units A and B are located at the ends of the silane coupling agent, the form is not particularly limited, as long as they form units corresponding to the formulas (I) and (II) representing the bonding units A and B. .

Regarding R ¹¹ in formulas (I) and (II), examples of halogen include chlorine, bromine, and fluorine. Examples of the branched or unbranched alkyl group having 1 to 30 carbon atoms include a methyl group and an ethyl group. Examples of branched or unbranched alkenyl groups having 2 to 30 carbon atoms include vinyl groups and 1-propenyl groups. Examples of the branched or unbranched alkynyl group having 2 to 30 carbon atoms include ethynyl group and propynyl group.

For R ¹² in formulas (I) and (II), examples of the branched or unbranched alkylene group having 1 to 30 carbon atoms include ethylene group and propylene group. Examples of branched or unbranched alkenylene groups having 2 to 30 carbon atoms include vinylene groups and 1-propenylene groups. Examples of the branched or unbranched alkynylene group having 2 to 30 carbon atoms include ethynylene group and propynylene group.

In a silane coupling agent containing a bonding unit A represented by formula (I) and a bonding unit B represented by formula (II), the number of repeats (v) of bonding unit A and the number of repeats (w) of bonding unit B are The total number of repetitions (v+w) is preferably in the range of 3 to 300.

When containing a silane coupling agent, the content of the silane coupling agent is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and preferably 20 parts by mass, based on 100 parts by mass of silica. The amount is more preferably 15 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

The cap rubber composition may contain a resin.
The resin is not particularly limited as long as it is commonly used in the tire industry, and examples include C5 resin, C9 resin, styrene resin, terpene resin, rosin resin, coumaron indene resin, and PT. -Butylphenol acetylene resin, acrylic resin, etc. These may be used alone or in combination of two or more. Among them, C5 resin is preferred.

The C5-based resin is a polymer containing a C5 fraction as a constituent monomer, and includes polymers polymerized with the C5 fraction as a main component (50% by mass or more). Specifically, C5 fraction (olefinic hydrocarbons such as 1-pentene, 2-pentene, 2-methyl-1-butene, 2-methyl-1,3-butadiene, 1,2-pentadiene, 1,3 - Diolefinic hydrocarbons such as pentadiene, etc.), copolymers made by copolymerizing two or more C5 fractions, as well as C5 fractions and other copolymers that can be copolymerized with them. Also included are copolymers with monomers.

Examples of other monomers include C9 fractions such as vinyltoluene, indene, and methylindene. These may be used alone or in combination of two or more.

Because the above-mentioned overall performance tends to be good, the C5-based resin is preferably a copolymer of a C5 fraction and another monomer, and a copolymer of a C5 fraction and a C9 fraction ( C5/C9 resin) is more preferred.

Commercially available C5 resins and other resins include, for example, Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical, Japan. Products from Nuri Kagaku Co., Ltd., Nippon Shokubai Co., Ltd., JXTG Energy Corporation, Arakawa Chemical Co., Ltd., Taoka Chemical Co., Ltd., ExxonMobil, Cray Valley, etc. can be used.

When containing a resin, the content of the resin relative to 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and preferably 30 parts by mass or less, more preferably 20 parts by mass. It is as follows. Within the above range, the above-mentioned overall performance tends to be good.

The cap rubber composition may contain a softening agent such as oil.
Examples of the oil include process oil, vegetable oil, or a mixture 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, 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, process oil is preferred.

Examples of the oil include Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Co., Ltd., Orisoi Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Showa Shell Sekiyu Co., Ltd., and Fuji Kosan Co., Ltd. You can use products such as

A softening agent that can be used in addition to oil is polyethylene glycol.
The polyethylene glycol is not particularly limited, but those represented by the following formula can be suitably used.
HO( _{CH2CH2O ) pH}
(p represents an integer from 5 to 100.)

As the polyethylene glycol, for example, products manufactured by Wako Pure Chemical Industries, Ltd., NOF Corporation, etc. can be used.

When containing a softener, the content of the softener is preferably 0.1 parts by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, based on 100 parts by mass of the rubber component. , more preferably 1 part by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

The cap 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 vegetable waxes and animal waxes; and synthetic waxes such as polymers of ethylene and propylene. These may be used alone or in combination of two or more. Among these, petroleum wax is preferred, and paraffin wax is more preferred.

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

When containing wax, the wax content is preferably 1 part by mass or more, more preferably 1.5 parts by mass or more, and preferably 20 parts by mass or less, more preferably 1.5 parts by mass or more, based on 100 parts by mass of the rubber component. Preferably it is 10 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

The cap rubber composition may also contain an anti-aging agent.
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 anti-aging agents; quinoline-based anti-aging agents 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; bis-, tris-, and polyphenol-based aging agents such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, etc. Examples include inhibitors. These may be used alone or in combination of two or more. Among these, p-phenylenediamine type anti-aging agents and quinoline type anti-aging agents are preferred.

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

When containing an anti-aging agent, the content of the anti-aging agent is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 10 parts by mass or less, based on 100 parts by mass of the rubber component. , more preferably 5 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

The cap rubber composition may contain stearic acid.
As the stearic acid, conventionally known ones can be used, and for example, products from NOF Corporation, NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc. can be used.

When containing stearic acid, the content of stearic acid is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 10 parts by mass or less, more preferably 1 part by mass or more, based on 100 parts by mass of the rubber component. Preferably it is 5 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

The cap rubber composition may contain zinc oxide.
As zinc oxide, conventionally known ones can be used, such as products from Mitsui Kinzoku Kogyo 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 containing zinc oxide, the content of zinc oxide is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 10 parts by mass or less, more preferably 1 part by mass or more, based on 100 parts by mass of the rubber component. Preferably it is 5 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

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

As the sulfur, for example, products manufactured by Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Co., Ltd., Nippon Karidome Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used.

When containing sulfur, the content of sulfur is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 10 parts by mass or less, more preferably It is 5 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

The cap rubber composition may contain a vulcanization accelerator.
Examples of vulcanization accelerators include thiazole vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazyl sulfenamide; tetramethylthiuram disulfide (TMTD); ), thiuram-based vulcanization accelerators such as tetrabenzylthiuram disulfide (TBzTD), tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); N-cyclohexyl-2-benzothiazolesulfenamide, N-t-butyl- 2-Benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N,N'-diisopropyl-2-benzothiazolesulfenamide, etc. Examples include sulfenamide vulcanization accelerators; guanidine vulcanization accelerators such as diphenylguanidine, diorthotolylguanidine, and orthotolyl biguanidine. These may be used alone or in combination of two or more. Among these, sulfenamide-based vulcanization accelerators and guanidine-based vulcanization accelerators are preferred.

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

When containing a vulcanization accelerator, 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, based on 100 parts by mass of the rubber component. parts, more preferably 5 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

In addition to the above-mentioned components, the rubber composition includes additives commonly used in the tire industry, such as organic peroxides; fillers such as calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica. (filler); etc. may be further blended. The content of these additives is preferably 0.1 to 200 parts by mass based on 100 parts by mass of the rubber component.

The cap rubber composition can be produced by, for example, kneading the above-mentioned components using a rubber kneading device such as an open roll or a Banbury mixer, and then vulcanizing the mixture.

As for the kneading conditions, in the base kneading step in which additives other than the vulcanizing agent and vulcanization accelerator are kneaded, the kneading temperature is usually 100 to 180°C, preferably 120 to 170°C. In the final kneading step of kneading the vulcanizing agent and vulcanization accelerator, the kneading temperature is usually 120°C or less, preferably 85 to 110°C. Further, a composition obtained by kneading a vulcanizing agent and a vulcanization accelerator is usually subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 140 to 190°C, preferably 150 to 185°C. Vulcanization time is usually 5 to 15 minutes.

<Base rubber composition>
The base rubber composition constituting the base tread in the tread portion of the pneumatic tire will be described below.

The base rubber composition can use the same chemicals as the cap rubber composition.

The base rubber composition contains isoprene rubber.
The content of isoprene rubber in 100% by mass of the rubber component is 90% by mass or more. The upper limit is not particularly limited and may be 100% by mass.

The base rubber composition contains a C5 resin.
The content of the C5 petroleum resin is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 15 parts by mass or less, more preferably 10 parts by mass, based on 100 parts by mass of the rubber component. It is not more than 5 parts by mass, more preferably not more than 5 parts by mass. Within the above range, the above-mentioned overall performance tends to be good.

The total content of the C5 petroleum resin and other resins is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 15 parts by mass or less, based on 100 parts by mass of the rubber component. , more preferably 10 parts by mass or less, still more preferably 5 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.
In addition, when resin other than C5 type petroleum resin is not contained, the said total content is synonymous with content of C5 type petroleum resin.

The base rubber composition contains carbon black (hereinafter also referred to as carbon black B) having a CTAB specific surface area of 30 m ² /g or more.
Carbon black B is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, N660, and the like. These may be used alone or in combination of two or more.

The CTAB specific surface area of carbon black B may be 30 m ² /g or more, preferably 35 m ² /g or more, and preferably 120 m ² /g or less, more preferably 80 m ² /g or less, and Preferably it is 50 m ² /g or less. Within the above range, the above-mentioned overall performance tends to be good.

The content of carbon black B is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 40 parts by mass, and preferably 100 parts by mass or less, based on 100 parts by mass of the rubber component. More preferably it is 80 parts by mass or less, and still more preferably 60 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

The base rubber composition may contain other carbon black (carbon black with a CTAB specific surface area of less than 30 m ² /g) in addition to carbon black B.
The content of other carbon black is preferably 0 to 10 parts by mass based on 100 parts by mass of the rubber component.

In addition to the above components, the base rubber composition may contain rubber components other than isoprene rubber, silica, silane coupling agents, softeners, wax, stearic acid, anti-aging agents, zinc oxide, sulfur, vulcanization accelerators, etc. They may be blended as appropriate. Suitable ranges of these contents are the same as those for the cap rubber composition.

The base rubber composition can be produced by the same method and under the same conditions as the cap rubber composition.

<Pneumatic tires>
The pneumatic tire of the present invention is manufactured by a conventional method using the cap rubber composition and the base rubber composition.
That is, the above-mentioned cap rubber composition and above-mentioned base rubber composition are extruded to fit the shapes of the cap tread and the base tread, respectively, at an unvulcanized stage, and then processed together with other tire components on a tire molding machine. An unvulcanized tire is formed by molding using the following method. By heating and pressurizing this unvulcanized tire in a vulcanizer, a tire having a tread portion including a cap tread and a base tread is obtained.

In addition, in the above pneumatic tire, the tread portion usually has a two-layer structure in which a cap tread (surface layer) and a base tread (inner surface layer) are laminated; however, the tread portion is not limited to this; May contain.

In the pneumatic tire, it is preferable that the total content of fillers in the cap rubber composition and the total content of fillers in the base rubber composition satisfy the following formula (A).
(A) α-β≧10
α: Total content of filler in the cap rubber composition [parts by mass]
β: Total content of filler in the base rubber composition [parts by mass]

In addition, in Formula (A), the total content of fillers is the total content of fillers such as carbon black and silica with respect to 100 parts by mass of the rubber component. When no filler other than carbon black is contained, the above-mentioned total content is synonymous with the content of carbon black.

In formula (A), the total content (α) of fillers in the cap rubber composition is preferably 35 parts by mass or more, more preferably 45 parts by mass, based on 100 parts by mass of the rubber component in the cap rubber composition. Above, it is more preferably 55 parts by mass or more, and preferably 85 parts by mass or less, more preferably 75 parts by mass or less, still more preferably 65 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

In formula (A), the total content (β) of fillers in the base rubber composition is preferably 20 parts by mass or more, more preferably 30 parts by mass, based on 100 parts by mass of the rubber component in the base rubber composition. Above, it is more preferably 40 parts by mass or more, and preferably 70 parts by mass or less, more preferably 60 parts by mass or less, still more preferably 50 parts by mass or less. Within the above range, the above-mentioned overall performance tends to be good.

The above pneumatic tires include passenger car tires; heavy-duty tires such as truck and bus tires; motorcycle tires; high-performance tires; winter tires such as studless tires; run-flat tires with side reinforcement layers; sound-absorbing materials such as sponge. A tire with a sound-absorbing member that has a sound absorbing member inside the tire cavity; A tire with a sealing member that has a sealant inside the tire or inside the tire cavity that can be sealed in the event of a puncture; Electronic components such as sensors and wireless tags that are installed inside the tire or inside the tire cavity. Although it can be used for tires with electronic components, it is suitable for tires for heavy loads.

The present invention will be specifically explained based on examples, but the present invention is not limited to these examples.
Below, various chemicals used in the examples will be explained.

<Cap rubber compound>
Isoprene rubber: TSR20 (natural rubber)
SBR1: Modified SBR synthesized in Production Example 1 below (styrene amount: 10% by mass, vinyl amount: 40% by mass, Mw: 300,000)
SBR2: JSR1502 manufactured by JSR Corporation (styrene content: 24% by mass, vinyl content: 16% by mass)
BR1: BR710 manufactured by Ube Industries, Ltd.
Carbon black 1: N220 (CTAB: 111 m ² /g)
Carbon black 2: N134 (CTAB: 135m ² /g)
Carbon black 3: Prototype (CTAB: 140 m ² /g, N ₂ SA: 146 m ² /g, IA: 135 mg/g)
Carbon black 4: Prototype (CTAB: 145 m ² /g, N ₂ SA: 160 m ² /g, IA: 151 mg/g)
Carbon black 5: Prototype (CTAB: 150 m ² /g, N ₂ SA: 181 m ² /g, IA: 177 mg/g)
Carbon black 6: N660 manufactured by Jiangix Black Cat (CTAB: 36m ² /g, COAN: 74ml/100g)
Silica: Ultrasil VN3 manufactured by Evonik Degussa (N ₂ SA: 167 m ² /g)
Additive 1: NXT (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive
Additive 2: PEG #4000 manufactured by NOF Corporation (polyethylene glycol, Mw: 4000, HO (CH ₂ CH ₂ O) _pH approximately 90)
Additive 3: OPPERA PR373 (C5/C9 resin) manufactured by ExxonMobil
Wax: Ozoace 0355 manufactured by Nippon Seiro Co., Ltd.
Anti-aging agent 1: Nocrac 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Anti-aging agent 2: Nocrac RD (poly(2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Stearic acid: stearic acid “Tsubaki” manufactured by NOF Corporation
Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Kinzoku Mining Co., Ltd. Sulfur: Powder sulfur manufactured by Tsurumi Chemical Co., Ltd. Vulcanization accelerator 1: Noxeler NS (Nt-butyl manufactured by Ouchi Shinko Chemical Co., Ltd.) -2-Benzothiazolylsulfenamide)
Vulcanization accelerator 2: Noxela CZ (N-cyclohexyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Vulcanization accelerator 3: Noxela D (1,3-diphenylguanidine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

<Base rubber compound>
Isoprene rubber: TSR20 (natural rubber)
BR2: BR1280 manufactured by LG Chem
Carbon black 1: N660 manufactured by Jiangix Black Cat (CTAB: 36 m ² /g, COAN: 74 ml / 100 g)
Carbon black 6: Prototype (CTAB: 150 m ² /g, N ₂ SA: 181 m ² /g, IA: 177 mg/g)
Carbon black 7: Showblack N550 manufactured by Cabot Japan Co., Ltd. (CTAB: 43m ² /g, COAN: 80ml/100g)
Additive 3: OPPERA PR373 (C5/C9 resin) manufactured by ExxonMobil
Additive 4: VIVATEC500 (TDAE oil) manufactured by H&R
Anti-aging agent 1: Nocrac 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Kinzoku Mining Co., Ltd. Sulfur: Powder sulfur manufactured by Tsurumi Chemical Co., Ltd. Vulcanization accelerator 1: Noxeler NS (Nt-butyl manufactured by Ouchi Shinko Chemical Co., Ltd.) -2-Benzothiazolylsulfenamide)

(Manufacturing example 1)
Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene were charged into an autoclave reactor purged with nitrogen. After adjusting the temperature of the contents of the reactor to 20° C., n-butyllithium was added to initiate polymerization. Polymerization was carried out under adiabatic conditions, and the maximum temperature reached 85°C. When the polymerization conversion rate reached 99%, 1,3-butadiene was added, and after polymerization was continued for an additional 5 minutes, 3-diethylaminopropyltrimethoxysilane was added as a modifier to carry out the reaction. After the polymerization reaction was completed, 2,6-di-tert-butyl-p-cresol was added. Next, the solvent was removed by steam stripping and dried using a heated roll whose temperature was controlled at 110° C. to obtain SBR1.

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

(Example and comparative example)
According to the formulation shown in Table 1, materials other than sulfur and vulcanization accelerator were kneaded for 5 minutes at 150°C using a 1.7L Banbury mixer manufactured by Kobe Steel, Ltd., and the kneaded material was mixed. Obtained. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and the mixture was kneaded for 5 minutes at 80°C using an open roll to form an unvulcanized cap rubber composition and an unvulcanized base rubber composition. I got something.
The obtained unvulcanized cap rubber composition is molded into the shape of a cap tread, and the unvulcanized base rubber composition is molded into the shape of a base tread, and then bonded together with other tire members to form an unvulcanized tire. Press vulcanization was performed for 12 minutes at 150° C. to produce a test tire (size: 295/75R22.5 (for trucks and buses)). The following evaluations were performed using the obtained test tires, and the results are shown in Table 1.

(durability)
Using a drum testing machine, each test tire was tested under the conditions of rim (8.25 x 22.5) and internal pressure (750 kPa), at a running speed of 45 km/h, from a load of 100% of the load index. The load was increased by 10% every 24 hours, the distance traveled until the tread part was damaged was measured, and the distance was expressed as an index with Comparative Example 1 being 100 (durability index). The larger the index, the longer the mileage and the greater the durability.

(wear resistance)
Each test tire was attached to all wheels of a vehicle, the groove depth of the tread part was measured after a mileage of 8000 km, the mileage when the tire groove depth decreased by 1 mm was calculated, and Comparative Example 1 was set as 100. (wear resistance index). The larger the index, the longer the mileage and the better the wear resistance.

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

(Chipping resistance)
Each test tire was mounted on all wheels of a vehicle, and after traveling 8000 km, the number of chipping locations in the tread portion was counted and expressed as an index when Comparative Example 1 was set as 100 (chipping resistance index). The larger the index, the fewer places where chipping occurs, indicating that the chipping resistance is excellent.

As shown in Table 1, the desired durability and abrasion resistance of the Examples were improved compared to the Comparative Examples. Moreover, the overall performance (total of each index) of durability, abrasion resistance, wet grip performance, and chipping resistance was also better than the comparative example.

Claims (4)

Equipped with a tread section including a cap tread and a base tread,
The cap rubber composition constituting the cap tread contains a rubber component containing isoprene rubber, styrene-butadiene rubber, and butadiene rubber, and carbon black having a cetyltrimethylammonium bromide specific surface area of 130 m ² /g or more,
The content of isoprene rubber in 100% by mass of the rubber component is 60% by mass or less,
The content of styrene-butadiene rubber in 100% by mass of the rubber component is 10% by mass or more,
The content of the carbon black having a specific surface area of 130 m ² /g or more of the cetyltrimethylammonium bromide is 45 parts by mass or less with respect to 100 parts by mass of the rubber component,
The base rubber composition constituting the base tread includes a rubber component having an isoprene rubber content of 90% by mass or more, a C5 resin, and carbon black having a cetyltrimethylammonium bromide specific surface area of 30 m ² /g or more. Contains and
The content of the carbon black having a specific surface area of 30 m ² /g or more of the cetyltrimethylammonium bromide is 50 parts by mass or less with respect to 100 parts by mass of the rubber component,
The following formula (A) is satisfied,
Pneumatic tires are tires for heavy loads .
(A) α−β≧10
α: Total content of filler in the cap rubber composition [parts by mass]
β: Total content of filler in the base rubber composition [parts by mass] The pneumatic tire according to claim 1 , wherein in the cap rubber composition, the content of isoprene rubber in 100% by mass of the rubber component is 40% by mass or more and 60% by mass or less . 3. The pneumatic tire according to claim 1, wherein the cap rubber composition has a silica content of 5 parts by mass or more based on 100 parts by mass of the rubber component. The pneumatic tire according to any one of claims 1 to 3 , wherein the cap rubber composition contains a resin.