JP7151134B2 - Rubber composition for tire and pneumatic tire - Google Patents

Description

TECHNICAL FIELD The present invention relates to a rubber composition for tires and a pneumatic tire.

Conventionally, tires have been required to have good fuel efficiency performance, and silica has been used as a filler to meet this requirement.

For example, Patent Literature 1 discloses that the inclusion of silica can improve fuel economy performance, but there is still room for improvement, and the development of other techniques is also desired.

JP 2007-177221 A

As a result of intensive studies, the present inventors have found that there is room for improvement in the dispersibility of silica and fuel efficiency performance in the conventional technology, and in particular, when fine particle silica with a large nitrogen adsorption specific surface area is used as silica, silica's It was found that there is room for improvement in dispersibility and fuel efficiency performance.
Accordingly, an object of the present invention is to provide a rubber composition having good silica dispersibility and fuel efficiency, and a pneumatic tire using the same.

The present invention comprises a rubber component containing 30% by mass or more of a styrene-butadiene rubber having an SiOR group (R is a hydrogen atom or a hydrocarbon group) and 100 parts by mass of a rubber component of silica having a nitrogen adsorption specific surface area of 210 m ² /g or more. 50 parts by mass or more, and at least one surfactant selected from the group consisting of polyoxyalkylene alkenyl ether sulfate salts and polyoxyalkylene alkyl ether sulfate salts, and the silica and the surfactant agent is kneaded with rubber at the same time.

The ratio X/Y of the content X (parts by mass) of the surfactant to the content Y (parts by mass) of the silane coupling agent is preferably 0.05 to 20.

The ratio Z/(X+Y) of the silica content Z (parts by mass), the surfactant content X (parts by mass), and the silane coupling agent content Y (parts by mass) is 3 to 30. Preferably.

The surfactant is preferably a polyoxyalkylene alkenyl ether sulfate salt.

The present invention also relates to a pneumatic tire having a tire member produced using the rubber composition.

According to the present invention, a rubber component containing 30% by mass or more of a styrene-butadiene rubber having an SiOR group (R is a hydrogen atom or a hydrocarbon group) and silica having a nitrogen adsorption specific surface area of 210 m ² /g or more are added to 100% of the rubber component. 50 parts by mass or more based on parts by mass, and at least one surfactant selected from the group consisting of polyoxyalkylene alkenyl ether sulfate salts and polyoxyalkylene alkyl ether sulfate salts, and the silica and the above Since the surfactant is a rubber composition for tires that is kneaded with rubber at the same time, it has good silica dispersibility and low fuel consumption performance.

The rubber composition for tires of the present invention comprises a rubber component containing 30% by mass or more of a styrene-butadiene rubber having an SiOR group (R is a hydrogen atom or a hydrocarbon group), and silica having a nitrogen adsorption specific surface area of 210 m ² /g or more. 50 parts by mass or more per 100 parts by mass of the rubber component, and at least one surfactant selected from the group consisting of polyoxyalkylene alkenyl ether sulfate salts and polyoxyalkylene alkyl ether sulfate salts, The silica and the surfactant are kneaded with the rubber at the same time.

Although the reason why the above rubber composition provides good silica dispersibility and fuel efficiency is not necessarily clear, it is speculated as follows.

Styrene-butadiene rubber (modified SBR) having SiOR groups can suppress the aggregation of silica particles and improve the dispersibility of silica particles by interacting with hydroxyl groups present on the silica surface. Furthermore, the surfactant preferably adsorbs to the hydrophilic silica surface due to the presence of the polyoxyalkylene portion and the presence of the sulfuric acid portion, and hydrophobizes the silica surface due to the alkenyl group or alkyl group present at the molecular end. As a result, the aggregation of silica particles can be suppressed, the dispersibility of silica can be improved, and the adsorption of the vulcanization accelerator to silica can be prevented. By using the modified SBR and the surfactant in combination, the dispersibility of silica is synergistically improved, and better dispersibility of silica and fuel efficiency than those of the prior art can be obtained. This is presumably because the presence of the surfactant improves the affinity between silica and the modified SBR. This effect is particularly pronounced in a rubber composition containing a relatively large amount of fine particle silica, such as 50 parts by mass or more of silica having a nitrogen adsorption specific surface area of 210 m ² /g or more per 100 parts by mass of the rubber component. be done. This is because although fine particle silica tends to aggregate due to the strength of the cohesive force of silica, by using the modified SBR and the surfactant together, the dispersibility of fine particle silica can be synergistically improved. , it is presumed that the effect of improving dispersibility is likely to be exhibited.
Therefore, in the present invention, silica having a nitrogen adsorption specific surface area of 210 m ² /g or more is 50 parts by mass or more with respect to 100 parts by mass of the rubber component, and even when a relatively large amount of fine particle silica is blended, good silica It is presumed that it is possible to provide a rubber composition having good dispersibility and low fuel consumption performance.
Furthermore, in the present invention, since the silica and the surfactant are kneaded with the rubber at the same time, the effect of using the modified SBR and the surfactant together can be obtained more remarkably.
Further, in the present invention, in addition to good silica dispersibility and fuel efficiency, good processing performance, wear resistance and grip performance are also obtained.
In addition, by using a styrene-butadiene rubber having a SiOR group (R is a hydrogen atom or a hydrocarbon group) and the above surfactant in combination, dispersibility of silica and fuel efficiency performance can be synergistically improved.

The rubber composition contains, as a rubber component, a styrene-butadiene rubber (modified SBR) having a SiOR group (R is a hydrogen atom or a hydrocarbon group).

The modified SBR may be SBR having a SiOR group. For example, terminal-modified SBR obtained by modifying at least one end of SBR with a compound (modifying agent) having a SiOR group (end-modified SBR having a SiOR group at the terminal) SBR), a main chain-modified SBR having a SiOR group in the main chain, or a main chain end-modified SBR having a SiOR group in the main chain and at the end (for example, a main chain having a SiOR group and at least one end being modified as described above main chain end-modified SBR modified with an agent) and the like. Moreover, the modified SBR may be further coupled with a polyfunctional compound such as a tin compound. These may be used alone or in combination of two or more.

The hydrocarbon group for R may be linear, branched, or cyclic, and includes aliphatic hydrocarbon groups, alicyclic hydrocarbon groups, aromatic hydrocarbon groups, combinations thereof, and the like. Among them, an aliphatic hydrocarbon group is preferred. Moreover, a straight chain is preferable. The number of carbon atoms in the hydrocarbon group is preferably 1 or more, preferably 20 or less, more preferably 12 or less, even more preferably 6 or less, and particularly preferably 3 or less, for the reason that the effect can be obtained more favorably. .

The aliphatic hydrocarbon group preferably has 1 or more carbon atoms, preferably 20 or less carbon atoms, more preferably 12 or less carbon atoms, more preferably 6 or less carbon atoms, and particularly preferably 3 or less carbon atoms. preferable. Preferable examples include alkyl groups having the above carbon number, and specific examples include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert- butyl group, pentyl group, hexyl group, heptyl group, 2-ethylhexyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, octadecyl group and the like. Among them, a methyl group, an ethyl group, an n-propyl group and an isopropyl group are preferred, and a methyl group and an ethyl group are more preferred, since they are more effective.

Alicyclic hydrocarbon groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclopropenyl, cyclobutenyl, cyclopentenyl, cyclohexenyl, cycloheptenyl, and cyclooctenyl groups. etc.

Aromatic hydrocarbon groups include phenyl, benzyl, phenethyl, tolyl, xylyl, and naphthyl groups. The substitution position of the methyl group on the benzene ring in the tolyl group and the xylyl group may be any of the ortho-, meta- and para-positions.

R is preferably a hydrogen atom or an aliphatic hydrocarbon group having the above carbon number, more preferably a hydrogen atom or an alkyl group having the above carbon number, since the effect can be obtained more favorably.

（式（Ａ）中、Ｒ^１及びＲ^２は、同一若しくは異なって、水素原子、炭化水素基、又はＯＲ基（Ｒは、水素原子又は炭化水素基）を表す。） A SiOR group is usually a group represented by the following formula (A).

(In formula (A), R ¹ and R ² are the same or different and represent a hydrogen atom, a hydrocarbon group, or an OR group (R is a hydrogen atom or a hydrocarbon group).)

The hydrocarbon groups for R ¹ and R ² include the same groups as the hydrocarbon group for R, and preferred embodiments are also the same. Examples of the OR group include the same groups as the groups described for the SiOR group (OR group in the SiOR group), and preferred embodiments are also the same.
Both R ¹ and R ² are preferably OR groups because the effect can be obtained more preferably. That is, the SiOR groups are preferably Si(OR) ₃ groups.

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

Modified SBR may be emulsion-polymerized styrene-butadiene rubber (E-SBR) or solution-polymerized styrene-butadiene rubber (S-SBR). These may be used alone or in combination of two or more.

The weight average molecular weight (Mw) of the modified SBR is preferably 200,000 or more, more preferably 300,000 or more, and still more preferably 500,000 or more. The upper limit of Mw is not particularly limited, but is preferably 2,000,000 or less, more preferably 1,500,000 or less, and still more preferably 1,000,000 or less. Within the above range, there is a tendency that good effects can be obtained.
In this specification, the weight average molecular weight (Mw) of the rubber component is measured by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: Tosoh Corporation). TSKGEL SUPERMULTIPORE HZ-M (manufactured by the company) can be obtained by standard polystyrene conversion based on the measured value.

The styrene content of the modified SBR is preferably 10% by mass or more, more preferably 15% by mass or more, and still more preferably 20% by mass or more. The styrene content is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and particularly preferably 25% by mass or less. Within the above range, there is a tendency that good effects can be obtained.
In this specification, the styrene content of SBR is calculated by H ¹ -NMR measurement.

The modified SBR has a vinyl content of preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 20% by mass or more, particularly preferably 30% by mass or more, and most preferably 40% by mass or more. Also, the vinyl content is preferably 70% by mass or less, more preferably 60% by mass or less. Within the above range, there is a tendency that good effects can be obtained.
In this specification, the amount of vinyl (amount of 1,2-bonded butadiene units) can be measured by infrared absorption spectrometry.

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

The content of modified SBR in 100% by mass of the rubber component is 30% by mass or more, preferably 50% by mass or more, more preferably 60% by mass or more, and the upper limit may be 100% by mass, When other rubber is contained, it is preferably 90% by mass or less, more preferably 80% by mass or less. Within the above range, there is a tendency that good effects can be obtained.

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

As the SBR (second SBR) other than the modified SBR, non-modified SBR having no functional group is preferable.

The preferred weight average molecular weight (Mw), styrene content and vinyl content of the second SBR are the same as the preferred weight average molecular weight (Mw), styrene content and vinyl content of the modified SBR.

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

The total content of SBR (total content of modified SBR and second SBR) in 100% by mass of the rubber component is preferably 30% by mass or more, more preferably 50% by mass or more, and still more preferably 70% by mass. Although the upper limit may be 100% by mass, it is preferably 90% by mass or less, more preferably 80% by mass or less when a rubber other than SBR is contained. Within the above range, there is a tendency that good effects can be obtained.

BR is not particularly limited, and for example, BR with a high cis content, BR containing syndiotactic polybutadiene crystals, butadiene rubber synthesized using a rare earth catalyst (rare earth BR), etc. can be used. These may be used alone or in combination of two or more. Among them, BR with a high cis content is preferred.

BR may be unmodified BR or modified BR. These may be used alone or in combination of two or more.
Examples of modified BR include modified BR into which functional groups similar to those of the above-described modified SBR are introduced.

The cis content of BR is preferably 90% by mass or more, more preferably 93% by mass or more, and still more preferably 95% by mass or more. By setting it to the lower limit or more, there is a tendency that good wear resistance performance can be obtained.
In this specification, the cis content of the rubber component can be measured by infrared absorption spectroscopy.

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

The content of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, preferably 50% by mass or less, more preferably 40% by mass or less, and still more preferably 30% by mass. % or less. Within the above range, there is a tendency that good effects can be obtained.

The total content of SBR (modified SBR and second SBR) and BR in 100% by mass of the rubber component is preferably 60% by mass or more, more preferably 80% by mass or more, and still more preferably 90% by mass or more, It may be 100% by mass. Within the above range, there is a tendency that good effects can be obtained.

The isoprene rubber includes natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, modified IR, and the like. As NR, for example, those commonly used in the tire industry, such as SIR20, RSS#3, and TSR20, can be used. The IR is not particularly limited, and for example IR2200 or the like commonly used in the tire industry can be used. Modified NR includes deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc. Modified NR includes epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. Examples of modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, and the like. These may be used alone or in combination of two or more. The content of the isoprene-based rubber in 100% by mass of the rubber component is not particularly limited as long as the effect is not impaired, and is preferably 5% by mass or more and preferably 20% by mass or less.

The rubber composition contains 50 parts by mass or more of silica having a nitrogen adsorption specific surface area of 210 m ² /g or more based on 100 parts by mass of the rubber component.
Examples of silica include dry silica (anhydrous silicic acid) and wet silica (hydrated silicic acid), but wet silica is preferred because it contains many silanol groups. These may be used alone or in combination of two or more.

The nitrogen adsorption specific surface area (N ₂ SA) of the silica is preferably 220 m ² /g or more, more preferably 230 m ² /g or more, and even more preferably 240 m ² /g or more. Also, the N ₂ SA is preferably 300 m ² /g or less, more preferably 270 m ² /g or less. Within the above range, there is a tendency that good effects can be obtained.
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 of Degussa, Rhodia, Tosoh Silica, Solvay Japan, Tokuyama, etc. can be used.

The silica content is 50 parts by mass or more, preferably 60 parts by mass or more, and more preferably 70 parts by mass or more based on 100 parts by mass of the rubber component. The content is preferably 150 parts by mass or less, more preferably 130 parts by mass or less, even more preferably 120 parts by mass or less, and particularly preferably 100 parts by mass or less. Within the above range, there is a tendency that good effects can be obtained.

The rubber composition may contain silica other than the silica (second silica) together with the silica. In this case, the total content of silica may be the same as the content when silica is used alone.

The rubber composition contains at least one surfactant selected from the group consisting of polyoxyalkylene alkenyl ether sulfate salts and polyoxyalkylene alkyl ether sulfate salts. These may be used alone or in combination of two or more.

The surfactant preferably has an ethylene oxide structure and/or a propylene oxide structure. Those having an ethylene oxide structure and/or a propylene oxide structure as a hydrophilic group can increase the affinity with silica, and the effect can be obtained more preferably. Among them, those having an ethylene oxide structure are preferable. In addition, when it has an ethylene oxide structure and/or a propylene oxide structure, the average number of added moles of ethylene oxide (EO) and propylene oxide (PO) (total number of average added moles of EO and PO) is 10 or more. Preferably, it is 13 or more. Also, the average number of added moles is preferably 80 or less, more preferably 60 or less, still more preferably 40 or less. In this case, the affinity with silica is further enhanced, and the effect is obtained more preferably.

The number of carbon atoms in the alkenyl group in the polyoxyalkylene alkenyl ether sulfate salt and the number of carbon atoms in the alkyl group in the polyoxyalkylene alkyl ether sulfate salt are preferably 8 or more, more preferably 10 or more. Also, the number of carbon atoms is preferably 20 or less, more preferably 18 or less, and still more preferably 15 or less. In this case, the dispersibility of silica is further enhanced, and the effect is obtained more preferably.

The salt form of the surfactant is not particularly limited, and alkali metal salts such as potassium and sodium; alkaline earth metal salts such as magnesium and calcium; amines such as monoethanolamine, diethanolamine and triethanolamine. salts; ammonium salts and the like. Among them, alkali metal salts and ammonium salts are preferable, and sodium salts and ammonium salts are more preferable, because the effect can be obtained more preferably.

The HLB value (calculated by the Griffin method) of the surfactant is preferably 12 or more, more preferably 13 or more. Also, the HLB value is preferably 19 or less, more preferably 17 or less. Within the above range, there is a tendency that good effects can be obtained.

As the polyoxyalkylene alkenyl ether sulfate salt and the polyoxyalkylene alkyl ether sulfate salt, the polyoxyalkylene alkenyl ether sulfate salt is preferable.

The polyoxyalkylene alkenyl ether sulfate salt is preferably a polyoxyethylene alkenyl ether sulfate salt, more preferably ammonium polyoxyethylene alkenyl ether sulfate.

As the polyoxyalkylene alkyl ether sulfate salt, a polyoxyethylene alkyl ether sulfate salt is preferable, and sodium polyoxyethylene alkyl ether sulfate is more preferable.

As the surfactant, for example, products of Kao Corporation, Lion Corporation, Lion Specialty Chemicals Co., Ltd., etc. can be used.

The content of the surfactant is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and still more preferably 2 parts by mass or more with respect to 100 parts by mass of the rubber component. Also, the content is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above range, there is a tendency that good effects can be obtained.

The rubber composition may contain a surfactant other than the surfactant (second surfactant) together with the surfactant. In this case, the total content of surfactants may be the same as the content when the surfactants are used alone.

The rubber composition preferably further contains a silane coupling agent.
The silane coupling agent is not particularly limited. (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-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, Momentive NXT, NXT-Z, etc. mercapto-based, vinyl-based such as vinyltriethoxysilane and vinyltrimethoxysilane, amino-based such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ- Glycidoxy-based such as glycidoxypropyltrimethoxysilane, nitro-based such as 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane and the like Examples include chloro-based compounds. These may be used alone or in combination of two or more. Among them, sulfide-based silane coupling agents and mercapto-based silane coupling agents are preferable, and mercapto-based silane coupling agents are more preferable, because they tend to obtain good effects.
In the present specification, the mercapto-based silane coupling agent is not limited to a silane coupling agent having a mercapto group (—SH), but a derivative group of the mercapto group (for example, a carbonylthio group (—S—C ( =O)-)) is also a concept including silane coupling agents. Here, the derivative group of the mercapto group is not limited to a group directly derived from the mercapto group (-SH) by a synthetic reaction, and the hydrogen atom of the mercapto group (-SH) is substituted with another atom or atomic group. The concept also includes a group having a structure such as

（式（１）中、Ｒ^１０１～Ｒ^１０３は、分岐若しくは非分岐の炭素数１～１２のアルキル基、分岐若しくは非分岐の炭素数１～１２のアルコキシ基、又は－Ｏ－（Ｒ^１１１－Ｏ）_ｚ－Ｒ^１１２（ｚ個のＲ^１１１は、分岐若しくは非分岐の炭素数１～３０の２価の炭化水素基を表す。ｚ個のＲ^１１１はそれぞれ同一でも異なっていてもよい。Ｒ^１１２は、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、炭素数６～３０のアリール基、又は炭素数７～３０のアラルキル基を表す。ｚは１～３０の整数を表す。）で表される基を表す。Ｒ^１０１～Ｒ^１０３はそれぞれ同一でも異なっていてもよい。Ｒ^１０４は、分岐若しくは非分岐の炭素数１～６のアルキレン基を表す。）

（式（２）及び（３）中、ｘは０以上の整数、ｙは１以上の整数である。Ｒ^２０１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表す。Ｒ^２０２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表す。Ｒ^２０１とＲ^２０２とで環構造を形成してもよい。） The mercapto-based silane coupling agent is preferably a silane coupling agent having a mercapto group (—SH), and a compound represented by the following formula (1) and/or a binding unit A represented by the following formula (2) A compound containing a bonding unit B represented by the following formula (3) is more preferable, and a compound containing a bonding unit A represented by the following formula (2) and a bonding unit B represented by the following formula (3) is even more preferable. Thereby, an effect is obtained more suitably.

(In Formula (1), R ¹⁰¹ to R ¹⁰³ are a branched or unbranched C 1-12 alkyl group, a branched or unbranched C 1-12 alkoxy group, or —O—(R ¹¹¹ — O) _z —R ¹¹² (z R ¹¹¹ represents a branched or unbranched divalent hydrocarbon group having 1 to 30 carbon atoms. Each of z R ¹¹¹ may be the same or different. R ¹¹² represents a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an aralkyl group having 7 to 30 carbon atoms; z represents an integer of 1 to 30. R ¹⁰¹ to R ¹⁰³ may be the same or different, and R ¹⁰⁴ is a branched or unbranched group having 1 to 6 carbon atoms. represents the alkylene group of.)

(In formulas (2) and (3), x is an integer of 0 or more, and y is an integer of 1 or more. R ²⁰¹ is hydrogen, halogen, a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or R ²⁰² represents an unbranched alkenyl group having 2 to 30 carbon atoms, a branched or unbranched alkynyl group having 2 to 30 carbon atoms, or an alkyl group in which the terminal hydrogen is substituted with a hydroxyl group or a carboxyl group. R ²⁰¹ and R ²⁰² represent a branched or unbranched C 1-30 alkylene group, a branched or unbranched C 2-30 alkenylene group, or a branched or unbranched C 2-30 alkynylene group. may form a ring structure.)

The compounds represented by formula (1) are described below.

By using the compound represented by the formula (1), silica is well dispersed and the effect is obtained better.

R ¹⁰¹ to R ¹⁰³ are a branched or unbranched C 1-12 alkyl group, a branched or unbranched C 1-12 alkoxy group, or —O—(R ¹¹¹ —O) _z —R ¹¹² represents the group represented. At least one of R ¹⁰¹ to R ¹⁰³ is preferably a group represented by —O—(R ¹¹¹ —O) _z —R ¹¹² , and two of R 101 to R 103 are —O—( More preferably, it is a group represented by R ¹¹¹ -O) _z -R ¹¹² and one of them is a branched or unbranched alkoxy group having 1 to 12 carbon atoms.

The branched or unbranched C 1-12 alkyl group represented by R ¹⁰¹ to R ¹⁰³ includes, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, iso-butyl group, sec- butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, 2-ethylhexyl group, octyl group, nonyl group and the like.
The upper limit of carbon number is preferably 5.

Examples of the branched or unbranched alkoxy group having 1 to 12 carbon atoms of R ¹⁰¹ to R ¹⁰³ include methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, iso-butoxy group, sec -butoxy group, tert-butoxy group, pentyloxy group, hexyloxy group, heptyloxy group, 2-ethylhexyloxy group, octyloxy group, nonyloxy group and the like.
The upper limit of carbon number is preferably 5.

In —O—(R ¹¹¹ —O) _z —R ¹¹² of R ¹⁰¹ to R ¹⁰³ , R ¹¹¹ is a branched or unbranched group having 1 to 30 carbon atoms (preferably 1 to 15 carbon atoms, more preferably 1 to 3) represents a divalent hydrocarbon group.
Examples of the hydrocarbon group include a branched or unbranched alkylene group having 1 to 30 carbon atoms, a branched or unbranched alkenylene group having 2 to 30 carbon atoms, and a branched or unbranched alkynylene group having 2 to 30 carbon atoms. , an arylene group having 6 to 30 carbon atoms, and the like. Among them, a branched or unbranched alkylene group having 1 to 30 carbon atoms is preferred.

The branched or unbranched C 1-30 alkylene group for R ¹¹¹ includes, for example, methylene group, ethylene group, propylene group, butylene group, pentylene group, hexylene group, heptylene group, octylene group, nonylene group and decylene group. group, undecylene group, dodecylene group, tridecylene group, tetradecylene group, pentadecylene group, hexadecylene group, heptadecylene group, octadecylene group and the like.
The upper limit of the number of carbon atoms is preferably 15, more preferably 3.

The branched or unbranched alkenylene group having 2 to 30 carbon atoms for R ¹¹¹ includes, for example, vinylene group, 1-propenylene group, 2-propenylene group, 1-butenylene group, 2-butenylene group, 1-pentenylene group, 2 -pentenylene group, 1-hexenylene group, 2-hexenylene group, 1-octenylene group and the like.
The upper limit of the number of carbon atoms is preferably 15, more preferably 3.

Branched or unbranched alkynylene group having 2 to 30 carbon atoms for R ¹¹¹ includes, for example, ethynylene group, propynylene group, butynylene group, pentynylene group, hexynylene group, heptynylene group, octinylene group, nonynylene group, decinylene group and undecynylene group. group, dodecinylene group, and the like.
The upper limit of the number of carbon atoms is preferably 15, more preferably 3.

Examples of the arylene group having 6 to 30 carbon atoms for R ¹¹¹ include a phenylene group, a tolylene group, a xylylene group and a naphthylene group.
The upper limit of the number of carbon atoms is preferably 15 carbon atoms.

z represents an integer of 1 to 30; The lower limit is preferably 2, more preferably 3, more preferably 5, and the upper limit is preferably 20, more preferably 7, still more preferably 6.

R ¹¹² is a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms or an aralkyl group having 7 to 30 carbon atoms. show. Among them, a branched or unbranched alkyl group having 1 to 30 carbon atoms is preferable.

The branched or unbranched C 1-30 alkyl group for R ¹¹² includes, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, iso-butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, 2-ethylhexyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, octadecyl group and the like. be done.
The lower limit of carbon number is preferably 3, more preferably 10, and the upper limit of carbon number is preferably 25, more preferably 15.

Branched or unbranched alkenyl groups having 2 to 30 carbon atoms for R ¹¹² include, for example, vinyl group, 1-propenyl group, 2-propenyl group, 1-butenyl group, 2-butenyl group, 1-pentenyl group, 2 -pentenyl group, 1-hexenyl group, 2-hexenyl group, 1-octenyl group, decenyl group, undecenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, pentadecenyl group, octadecenyl group and the like.
The lower limit of carbon number is preferably 3, more preferably 10, and the upper limit of carbon number is preferably 25, more preferably 15.

Examples of the aryl group having 6 to 30 carbon atoms for R ¹¹² include a phenyl group, a tolyl group, a xylyl group, a naphthyl group and a biphenyl group.
The lower limit of carbon number is preferably 10, and the upper limit of carbon number is preferably 20.

Examples of the aralkyl group having 7 to 30 carbon atoms for R ¹¹² include a benzyl group and a phenethyl group.
The lower limit of the number of carbon atoms is preferably 10 carbon atoms, and the upper limit of the number of carbon atoms is preferably 20 carbon atoms.

Specific examples of the group represented by —O—(R ¹¹¹ —O) _z —R ¹¹² include —O—(C ₂ H ₄ —O) ₅ —C ₁₁ H ₂₃ , —O—(C ₂ H ₄ —O) ₅ —C ₁₂ H ₂₅ , —O—(C ₂ H ₄ —O) ₅ —C ₁₃ H ₂₇ , —O—(C ₂ H ₄ —O) ₅ —C ₁₄ H ₂₉ , —O -( _C2H4 -O) ₅ - _C15H31 , -O- _{( C2H4 -} O) ₃ - _C13H27 , -O- _{( C2H4 -} O) _{4 - C13H 27} , —O—(C ₂ H ₄ —O) ₆ —C ₁₃ H ₂₇ , —O—(C ₂ H ₄ —O) ₇ —C ₁₃ H ₂₇ and the like. Among them, -O-(C ₂ H ₄ -O) ₅ -C ₁₁ H ₂₃ , -O-(C ₂ H ₄ -O) ₅ -C ₁₃ H ₂₇ , -O-(C ₂ H ₄ -O) ₅ —C ₁₅ H ₃₁ , —O—(C ₂ H ₄ —O) ₆ —C ₁₃ H ₂₇ are preferred.

Examples of the branched or unbranched C1-C6 alkylene group for R ¹⁰⁴ include the same branched or unbranched C 1-30 alkylene groups for R ¹¹¹ .
The upper limit of carbon number is preferably 5.

Examples of the compound represented by the above formula (1) include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and the following formula (Si363 manufactured by EVONIK-DEGUSSA) and the like, and compounds represented by the following formula can be preferably used. These may be used alone or in combination of two or more.

Next, a compound containing a binding unit A represented by formula (2) and a binding unit B represented by formula (3) will be described.

In the silane coupling agent having the above structure, the content of the bonding unit A is preferably 30 mol% or more, more preferably 50 mol% or more, and preferably 99 mol%, for the reason that the effect can be obtained more favorably. 90 mol % or less, more preferably 90 mol % or less. The content of the binding unit B is preferably 1 mol% or more, more preferably 5 mol% or more, still 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. Also, the total content of the binding units A and B is preferably 95 mol % or more, more preferably 98 mol % or more, and particularly preferably 100 mol %.
In addition, the content of the bonding units A and B is the amount including the case where the bonding units A and B are positioned at the terminal 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 (2) and (3) representing the bonding units A and B. .

Halogen for R ²⁰¹ includes chlorine, bromine, fluorine and the like.

The branched or unbranched C 1-30 alkyl group for R ²⁰¹ includes methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, iso-butyl group, sec-butyl group, tert- butyl group, pentyl group, hexyl group, heptyl group, 2-ethylhexyl group, octyl group, nonyl group, decyl group and the like. The number of carbon atoms in the alkyl group is preferably 1-12.

The branched or unbranched alkenyl group having 2 to 30 carbon atoms for R ²⁰¹ includes vinyl group, 1-propenyl group, 2-propenyl group, 1-butenyl group, 2-butenyl group, 1-pentenyl group and 2-pentenyl. group, 1-hexenyl group, 2-hexenyl group, 1-octenyl group and the like. The alkenyl group preferably has 2 to 12 carbon atoms.

The branched or unbranched alkynyl group having 2 to 30 carbon atoms for R ²⁰¹ includes ethynyl group, propynyl group, butynyl group, pentynyl group, hexynyl group, heptynyl group, octynyl group, nonynyl group, decynyl group, undecynyl group, A dodecynyl group and the like can be mentioned. The alkynyl group preferably has 2 to 12 carbon atoms.

The branched or unbranched alkylene group having 1 to 30 carbon atoms for R ²⁰² includes an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group, an undecylene group, Dodecylene group, tridecylene group, tetradecylene group, pentadecylene group, hexadecylene group, heptadecylene group, octadecylene group, and the like. The alkylene group preferably has 1 to 12 carbon atoms.

The branched or unbranched alkenylene group having 2 to 30 carbon atoms for R ²⁰² includes vinylene group, 1-propenylene group, 2-propenylene group, 1-butenylene group, 2-butenylene group, 1-pentenylene group and 2-pentenylene group. group, 1-hexenylene group, 2-hexenylene group, 1-octenylene group and the like. The alkenylene group preferably has 2 to 12 carbon atoms.

The branched or unbranched alkynylene group having 2 to 30 carbon atoms for R ²⁰² includes an ethynylene group, a propynylene group, a butynylene group, a pentynylene group, a hexynylene group, a heptynylene group, an octinylene group, a nonynylene group, a decinylene group, an undecynylene group, A dodecinylene group and the like can be mentioned. The alkynylene group preferably has 2 to 12 carbon atoms.

In a compound containing a bonding unit A represented by formula (2) and a bonding unit B represented by formula (3), the total number of repetitions of the repeating number (x) of the bonding unit A and the repeating number (y) of the bonding unit B The number (x+y) is preferably in the range of 3-300. Within this range, since the mercaptosilane of the bonding unit B is covered by the —C ₇ H ₁₅ of the bonding unit A, it is possible to suppress the scorch time from being shortened and to achieve good reactivity with silica and rubber components. can be secured.

Examples of compounds containing a binding unit A represented by formula (2) and a binding unit B represented by formula (3) include NXT-Z30, NXT-Z45, and NXT-Z60 manufactured by Momentive. can be done. These may be used alone or in combination of two or more.

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

The content of the silane coupling agent is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, relative to 100 parts by mass of silica. Moreover, 20 mass parts or less are preferable, and, as for the said content, 15 mass parts or less are more preferable. Within the above range, there is a tendency that good effects can be obtained.

The ratio X/Y of the content X (parts by mass) of the surfactant to the content Y (parts by mass) of the silane coupling agent is preferably 0.05 to 20. Within the above range, there is a tendency that good effects can be obtained. Here, the content means the content per 100 parts by mass of the rubber component.
The lower limit of X/Y is preferably 0.1, more preferably 0.2, more preferably 0.25, and the upper limit of X/Y is preferably 10, more preferably 5, more preferably 2, 1 is most preferred.

The ratio of the content Z (parts by mass) of silica having a nitrogen adsorption specific surface area of 210 m ² /g or more, the content X (parts by mass) of the surfactant, and the content Y (parts by mass) of the silane coupling agent Z/(X+Y) is preferably 3-30. Within the above range, there is a tendency that good effects can be obtained. Here, the content means the content per 100 parts by mass of the rubber component.
The lower limit of Z/(X+Y) is preferably 4, more preferably 5, and the upper limit of Z/(X+Y) is preferably 20, more preferably 15, still more preferably 12, particularly preferably 10, most preferably is 8.

The rubber composition preferably contains carbon black. Thereby, an effect is suitably obtained.
Examples of carbon black include, but are not limited to, N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. These may be used alone or in combination of two or more.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 70 m ² /g or more, more preferably 80 m ² /g or more, and even more preferably 100 m ² /g or more. The N ₂ SA is preferably 300 m ² /g or less, more preferably 250 m ² /g or less, still more preferably 200 m ² /g or less, and particularly preferably 160 m ² /g or less. Within the above range, there is a tendency that good effects can be obtained.
The nitrogen adsorption specific surface area of carbon black is determined according to JIS K 6217-2:2001.

As carbon black, for example, products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Corporation, Shin Nikka Carbon Co., Ltd., Columbia Carbon Co., Ltd. can be used.

The content of carbon black is preferably 2 parts by mass or more, more preferably 3 parts by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 100 parts by mass or less, more preferably 60 parts by mass or less, still more preferably 30 parts by mass or less, particularly preferably 20 parts by mass or less, and most preferably 10 parts by mass or less. Within the above range, there is a tendency that good effects can be obtained.

The ratio A/Z of the content A (parts by mass) of carbon black to the content Z (parts by mass) of silica having a nitrogen adsorption specific surface area of 210 m ² /g or more is preferably 0.01 to 120. Within the above range, there is a tendency that good effects can be obtained. Here, the content means the content per 100 parts by mass of the rubber component.
The lower limit of A/Z is preferably 0.02, more preferably 0.03, and the upper limit of A/Z is preferably 20, more preferably 1, still more preferably 0.5, particularly preferably 0.5. 2.

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

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

The content of the oil is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and still more preferably 20 parts by mass or more with respect to 100 parts by mass of the rubber component. Moreover, the content is preferably 70 parts by mass or less, more preferably 50 parts by mass or less. Within the above range, there is a tendency that good effects can be obtained.
The content of oil also includes the amount of oil contained in the rubber (oil-extended rubber).

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

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

The sulfur content is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, relative to 100 parts by mass of the rubber component. The above content is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 3 parts by mass or less. Within the above range, there is a tendency that good effects can be obtained.

The rubber composition preferably contains a vulcanization accelerator.
Vulcanization accelerators include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole (MBT) and dibenzothiazyl disulfide (MBTS); tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), tetrakis (2-ethylhexyl) thiuram-based vulcanization accelerators such as thiuram disulfide (TOT-N); N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfen Sulfenamides such as amides (CBS), N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N,N'-diisopropyl-2-benzothiazolesulfenamide vulcanization accelerator; Guanidine vulcanization accelerators such as 1,3-diphenylguanidine (DPG), dioltolylguanidine, and orthotolylbiguanidine can be mentioned. These may be used alone or in combination of two or more. Among them, thiazole-based vulcanization accelerators, sulfenamide-based vulcanization accelerators, and guanidine-based vulcanization accelerators are preferable because they are more suitable for obtaining effects. Further, the combined use of a sulfenamide-based vulcanization accelerator and a guanidine-based vulcanization accelerator, and the combined use of a thiazole-based vulcanization accelerator and a guanidine-based vulcanization accelerator are also preferable.
Preferred thiazole-based vulcanization accelerators, sulfenamide-based vulcanization accelerators, and guanidine-based vulcanization accelerators are MBT, MBTS; TBBS, CBS, and DPG, respectively.

The content of the vulcanization accelerator is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, relative to 100 parts by mass of the rubber component. Moreover, the content is preferably 10 parts by mass or less, more preferably 7 parts by mass or less. Within the above range, there is a tendency that good effects can be obtained.

The rubber composition may contain a resin.
The resin is not particularly limited as long as it is commonly used in the tire industry, and includes rosin-based resin, coumarone-indene resin, α-methylstyrene-based resin, terpene-based resin, pt-butylphenolacetylene resin, and acrylic resin. resin, C5 resin, C9 resin, and the like. Commercially available products include Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical, Nichinuri Chemical Co., Ltd., Japan. Catalysts, products of JX Nippon Oil & Energy Corporation, Arakawa Chemical Industries, Ltd., Taoka Chemical Industries, Ltd., Toagosei Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

From the viewpoint of the performance balance, the content of the resin is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, and preferably 100 parts by mass or less with respect to 100 parts by mass of the rubber component. More preferably, it is 50 parts by mass or less.

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

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

The content of the antioxidant is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, relative to 100 parts by mass of the rubber component. Moreover, the content is preferably 10 parts by mass or less, more preferably 5 parts by mass or less. Within the above range, there is a tendency that good effects can be obtained.

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

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

The wax content is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, and preferably 20 parts by mass or less with respect to 100 parts by mass of the rubber component, from the viewpoint of the performance balance. More preferably, it is 10 parts by mass or less.

The rubber composition preferably contains a fatty acid.
As the fatty acid, conventionally known fatty acids can be used, and examples thereof include stearic acid, oleic acid, palmitic acid, etc. Stearic acid is preferred because it tends to provide good effects. These may be used alone or in combination of two or more.
As the fatty acid, products of NOF Corporation, NOF Corporation, Kao Corporation, Wako Pure Chemical Industries, Ltd., Chiba Fatty Acids Co., Ltd., and the like can be used.

The content of fatty acid is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, relative to 100 parts by mass of the rubber component. Moreover, the content is preferably 10 parts by mass or less, more preferably 5 parts by mass or less. Within the above range, there is a tendency that good effects can be obtained.

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

The content of zinc oxide is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, relative to 100 parts by mass of the rubber component. Moreover, the content is preferably 10 parts by mass or less, more preferably 5 parts by mass or less. Within the above numerical range, the effect tends to be obtained more favorably.

In addition to the above components, the rubber composition may contain additives generally used in the tire industry, such as fillers such as organic peroxides and magnesium sulfate. The content of each of these fillers is preferably 0.1 parts by mass or more and preferably 200 parts by mass or less with respect to 100 parts by mass of the rubber component.

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

As for the kneading conditions, the kneading temperature is usually 100 to 180°C, preferably 120 to 170°C in the base kneading step for kneading additives other than the cross-linking agent (vulcanizing agent) and the vulcanization accelerator. In the finishing kneading step of kneading the vulcanizing agent and the vulcanization accelerator, the kneading temperature is usually 120°C or lower, preferably 85 to 110°C. A composition obtained by kneading a vulcanizing agent and a vulcanization accelerator is usually subjected to vulcanization treatment such as press vulcanization. The vulcanization temperature is generally 140-190°C, preferably 150-185°C.

In the present invention, the rubber composition is obtained by a production method in which the silica and the surfactant are kneaded with rubber at the same time. Here, rubber and kneading at the same time means that the silica and the surfactant are put into a kneader and kneaded in the same kneading step. For example, in the base kneading step, both may be put into a kneader and kneaded. Moreover, when the base kneading step is composed of a plurality of steps, both of them may be put into a kneader and kneaded in one of the plurality of steps.

Of the silica blended in the rubber composition, preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, most preferably 100% by mass of the silica is the surfactant and kneaded with rubber at the same time. Thereby, the effect can be obtained better.
Similarly, among the surfactants blended in the rubber composition, preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, most preferably 100% by mass of the surfactant It is preferred that the agent is kneaded with the rubber at the same time as the silica. Thereby, the effect can be obtained better.

Since the rubber composition has good fuel economy performance, it can be used for tread (cap tread), sidewall, base tread, undertread, clinch, bead apex, breaker cushion rubber, carcass cord covering rubber, insulation. , chafers, inner liners, etc., and tire members such as side reinforcing layers of run-flat tires. Among others, it is preferably used for treads.

(pneumatic tire)
The pneumatic tire of the present invention is manufactured by a normal method using the rubber composition. That is, the rubber composition blended with the above components is extruded according to the shape of each tire member such as the tread in an unvulcanized stage, and molded together with other tire members on a tire molding machine by a normal method. to form an unvulcanized tire. A tire is obtained by heating and pressurizing this unvulcanized tire in a vulcanizer.

The above pneumatic tires include tires for passenger cars, tires for large passenger cars, tires for large SUVs, tires for trucks and buses, tires for racing, studless tires (winter tires), tires for motorcycles, run-flat tires, and aircraft tires. , mining tires, etc.

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

(Production example 1)
A nitrogen purged autoclave reactor is charged with cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene. After adjusting the temperature of the contents of the reactor to 20° C., n-butyllithium is added to initiate polymerization. It polymerizes under adiabatic conditions and reaches a maximum temperature of 85°C. When the polymerization conversion rate reaches 99%, butadiene is added, and after 5 minutes of polymerization, 3-diethylaminopropyltrimethoxysilane is added as a modifier and reacted for 15 minutes. After completion of the polymerization reaction, 2,6-di-tert-butyl-p-cresol is added. Then, the solvent is removed by steam stripping, and the mixture is dried with a hot roll controlled at 110° C. to obtain a modified styrene-butadiene rubber (modified SBR).

(Production example 2)
An unmodified styrene-butadiene rubber (unmodified SBR) is obtained in the same manner as in Production Example 1, except that no modifier is added.

The SBRs obtained in the above production examples are evaluated as follows.

(Weight average molecular weight (Mw))
Gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation) based on standard polystyrene conversion calculate.

(Styrene content)
The styrene content of SBR is calculated by H ¹ -NMR measurement.

(Vinyl content)
The vinyl content of SBR is measured by infrared absorption spectroscopy.

Various chemicals used in Examples and Comparative Examples will be collectively described.
Modified SBR: Modified SBR (SBR prepared in Production Example 1 above, styrene content: 21% by mass, vinyl content: 55% by mass, Mw: 850,000)
Unmodified SBR: Unmodified SBR (SBR prepared in Production Example 2 above, styrene content: 21% by mass, vinyl content: 55% by mass, Mw: 850,000)
BR: BR150B (cis content: 97% by mass) manufactured by Ube Industries, Ltd.
Silica 1: Ultrasil VN3 from Evonik Degussa (N ₂ SA: 180 m ² /g)
Silica 2: 9000GR (N ₂ SA: 230 m ² /g) manufactured by Evonik Degussa
Silica 3: Nipsil VN3 (N ₂ SA: 270 m ² /g) manufactured by Tosoh Corporation
Carbon black: Show Black N134 (N ₂ SA: 148 m ² /g) manufactured by Cabot Japan Co., Ltd.
Surfactant 1: Kao Corporation Ramtel PD-104 (polyoxyalkylene alkenyl ether ammonium sulfate)
Surfactant 2: Kao Corporation Emal E-27C (sodium polyoxyethylene lauryl ether sulfate, carbon number of alkyl group: 12)
Silane coupling agent: Momentive NXT-Z45 (compound containing bonding unit A and bonding unit B (bonding unit A: 55 mol%, bonding unit B: 45 mol%))
Oil: Diana Process AH-24 (aromatic process oil) manufactured by Idemitsu Kosan Co., Ltd.
Anti-aging agent: Antigen 6C manufactured by Sumitomo Chemical Co., Ltd. (anti-aging agent, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine)
Wax: Ozoace 0355 manufactured by Nippon Seiro Co., Ltd.
Stearic acid: Camellia zinc oxide manufactured by NOF Corporation: Zinc oxide type 2 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: HK-200-5 (powder sulfur containing 5% by mass of oil) manufactured by Hosoi Chemical Industry Co., Ltd.
Vulcanization accelerator 1: Noxceler CZ (N-cyclohexyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Vulcanization accelerator 2: Noxceler D (1,3-diphenylguanidine) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.

(Examples and Comparative Examples)
According to the compounding recipe shown in Table 1, using a 1.7 L Banbury mixer manufactured by Kobe Steel, Ltd., chemicals other than sulfur and a vulcanization accelerator were kneaded for 5 minutes at a set temperature of 150 ° C., Get a kneaded product. Next, sulfur and a vulcanization accelerator are added to the resulting kneaded material, and kneaded at 100° C. for 5 minutes using an open roll to obtain an unvulcanized rubber composition. The resulting unvulcanized rubber composition is press vulcanized at 170° C. for 20 minutes to obtain a vulcanized rubber composition (vulcanized rubber sheet). Here, the silica and the surfactant are put into the kneader at the same time.

By performing the following evaluation using the unvulcanized rubber composition and the vulcanized rubber composition obtained as described above, Table 1 or values close thereto are obtained.

(Mooney viscosity (processing performance))
According to JIS K 6300-1 "Unvulcanized rubber-Physical properties-Part 1: Determination of viscosity and scorch time by Mooney viscometer", using a Mooney viscosity tester, heated by preheating for 1 minute 130 C., the small rotor is rotated, and the Mooney viscosity (ML.sub.1 ₊₄ /130.degree. C.) of the unvulcanized rubber composition is measured after 4 minutes. Assuming that the measurement result of Comparative Example 1 is 100, the Mooney viscosity of each formulation is expressed as an index according to the following formula. The larger the index, the lower the viscosity and the better the processing performance.
(Mooney viscosity index) = (Mooney viscosity of Comparative Example 1) / (Mooney viscosity of each formulation) x 100

(Paine effect (silica dispersibility))
Using RPA2000 manufactured by Alpha Technology Co., Ltd., the strain dependence of the storage elastic modulus of the vulcanized rubber composition was measured under the conditions of a measurement temperature of 110° C. (1 minute of preheating), a frequency of 6 cpm, and an amplitude of 0.28 to 10%. , the value of the storage elastic modulus when the strain amount is 0.56%. The results are indexed with the value of Comparative Example 1 set to 100 (dispersibility index). The larger the index, the less the poorly dispersed lumps of the filler and the better the dispersibility of the filler. In this example, the proportion of silica in the filler is large, so the Payne effect index mainly indicates the dispersibility of silica.

(Low fuel consumption performance)
Using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho Co., Ltd., the loss tangent (tan δ) of the vulcanized rubber sheet was measured under the conditions of a temperature of 50 ° C., an initial strain of 10%, a dynamic strain of 2%, and a frequency of 10 Hz. Assuming that tan δ of Comparative Example 1 is 100, the fuel economy performance index is calculated by the following formula. A higher fuel economy performance index indicates better fuel economy performance.
(Fuel efficiency performance index) = (tan δ of Comparative Example 1) / (tan δ of each formulation) x 100

(Abrasion resistance performance)
Using an LAT tester (Laboratory Ablation and Skid Tester), the volume loss of each vulcanized rubber composition is measured under the conditions of a load of 40 N, a speed of 20 km/h, and a slip angle of 5°. Assuming that the volume loss of Comparative Example 1 is 100, the LAT wear index is calculated by the following formula. A larger index indicates better wear resistance.
(Abrasion resistance performance index) = (Volume loss of Comparative Example 1) / (Volume loss of each formulation) x 100

Claims (5)

A rubber component containing 30% by mass or more of styrene-butadiene rubber having an SiOR group (R is a hydrogen atom or a hydrocarbon group) and silica having a nitrogen adsorption specific surface area of 210 m ² /g or more are added at 50 parts by mass per 100 parts by mass of the rubber component. Part by mass or more, and at least one surfactant selected from the group consisting of polyoxyalkylene alkenyl ether sulfate salts and polyoxyalkylene alkyl ether sulfate salts, wherein the silica and the surfactant are A rubber composition for tires that is kneaded with rubber at the same time. The rubber composition for tires according to claim 1, wherein the ratio X/Y of the content X (parts by mass) of the surfactant and the content Y (parts by mass) of the silane coupling agent is 0.05 to 20. The ratio Z/(X+Y) of the silica content Z (parts by mass), the surfactant content X (parts by mass), and the silane coupling agent content Y (parts by mass) is 3 to 30. A rubber composition for a tire according to claim 1 or 2. The rubber composition for tires according to any one of claims 1 to 3, wherein the surfactant is a polyoxyalkylene alkenyl ether sulfate ester salt. A pneumatic tire comprising a tire member produced using the rubber composition according to any one of claims 1 to 4.