JP2022017836A - Tire rubber composition and tire - Google Patents

Abstract

To provide a tire rubber composition that can improve the general performances of fuel economy and chipping resistance at high speed and provide a tire.SOLUTION: A tire rubber composition contains a rubber component including isoprene rubber, butadiene rubber and styrene-butadiene rubber, silica, and a silane coupling agent. The silane coupling agent contains an organic silicon compound including alkoxysilyl groups and sulfur atoms, where, carbon atoms connecting the alkoxysilyl groups and sulfur atoms are 6 or more in number.SELECTED DRAWING: None

Description

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

In recent years, mainly SUVs (Sport Utility Vehicles) and pickup vehicles are popular models not only in the North American market but also in the Middle East, South Africa, and Asian markets. In these areas, vehicles often travel on rough terrain (rough roads) at high speeds for long periods of time, so tires are required to have not only low fuel consumption performance but also excellent chipping resistance at high speeds. It is being done.

An object of the present invention is to provide a rubber composition for a tire and a tire which solves the above-mentioned problems and improves the overall performance of fuel efficiency and chipping resistance at high speed.

The present invention contains a rubber component containing isoprene-based rubber, butadiene rubber and styrene-butadiene rubber, silica, and a silane coupling agent, wherein the silane coupling agent contains an alkoxysilyl group and a sulfur atom, and is alkoxysilyl. The present invention relates to a rubber composition for a tire containing an organic silicon compound having 6 or more carbon atoms connecting a group and a sulfur atom.

The content of isoprene-based rubber in 100% by mass of the rubber component is preferably less than 50% by mass.

The content of butadiene rubber in 100% by mass of the rubber component is preferably less than 50% by mass.

The content of styrene-butadiene rubber in 100% by mass of the rubber component is preferably less than 80% by mass.

It is preferable that the content of silica with respect to 100 parts by mass of the rubber component exceeds 50 parts by mass.

It is preferable to contain silica having an average primary particle diameter of less than 18 nm.

Further, the content of isoprene-based rubber, styrene-butadiene rubber and butadiene rubber in 100% by mass of the rubber component containing carbon black, and the content of silica and carbon black with respect to 100 parts by mass of the rubber component are the following formulas (1) to (3). ) Is preferably satisfied.
(1) Isoprene-based rubber content <Styrene-butadiene rubber content (2) butadiene rubber content <Styrene-butadiene rubber content (3) | Isoprene-based rubber content-butadiene rubber content | Silica content-Carbon black content |

It is preferable that the content of styrene-butadiene rubber and isoprene-based rubber in 100% by mass of the rubber component satisfies the following formula.
10% by mass ≤ content of styrene-butadiene rubber-content of isoprene-based rubber ≤ 70% by mass

It is preferable that the content of styrene-butadiene rubber and butadiene rubber in 100% by mass of the rubber component satisfies the following formula.
1% by mass ≤ content of styrene-butadiene rubber-content of butadiene rubber ≤ 50% by mass

It is preferable that the content of isoprene-based rubber and butadiene rubber in 100% by mass of the rubber component satisfies the following formula.
5% by mass ≤ | Isoprene-based rubber content-butadiene rubber content | ≤50% by mass

It is preferable that the contents of silica and carbon black with respect to 100 parts by mass of the rubber component satisfy the following formula.
15 parts by mass ≤ | Silica content-Carbon black content | ≤ 80 parts by mass

It is preferable to contain silica having an average primary particle diameter of less than 18 nm and carbon black.

The present invention also relates to a tire having a tire member made of the rubber composition.

According to the present invention, a rubber component containing isoprene-based rubber, butadiene rubber and styrene-butadiene rubber, silica and a silane coupling agent are contained, and the silane coupling agent contains an alkoxysilyl group and a sulfur atom, and Since the rubber composition for a tire contains an organic silicon compound in which the number of carbon atoms connecting the alkoxysilyl group and the sulfur atom is 6 or more, it is possible to improve the overall performance of low fuel consumption performance and chipping resistance at high speed.

The present invention contains a rubber component containing isoprene-based rubber, butadiene rubber and styrene-butadiene rubber, silica, and a silane coupling agent, wherein the silane coupling agent contains an alkoxysilyl group and a sulfur atom, and is alkoxysilyl. A rubber composition for a tire containing an organic silicon compound having 6 or more carbon atoms connecting a group and a sulfur atom. The rubber composition can improve the overall performance of low fuel consumption performance and chipping resistance at high speed.

The reason why the above-mentioned effects are obtained is not always clear, but it is presumed that the effects are achieved by the following mechanism.
For the problem of cutting or chipping of the rubber composition, it is effective to fill it with a high filler (60 parts by mass or more with respect to 100 parts by mass of the rubber component) to improve the reinforcing property, but the rubber tends to generate heat. There is a contradictory problem. In addition, by mixing three types of rubber components, isoprene-based rubber, butadiene rubber, and styrene-butadiene rubber, phases with different hardness will be mixed microscopically, making it difficult for impact and cracks to be transmitted, resulting in reinforcing properties. Coupled with this, cutting and chipping are less likely to occur. In order to improve the overall performance of low fuel consumption performance and chipping resistance at high speed, it is considered that the uniformity of silica and rubber is important, and if the dispersion of silica becomes non-uniform, heat generation increases due to stress concentration. It is thought that the rubber is likely to be cut or chipped. On the other hand, an organic silicon compound containing an alkoxysilyl group and a sulfur atom as a silane coupling agent and having 6 or more carbon atoms connecting the alkoxysilyl group and the sulfur atom, that is, a long-chain silane coupling agent. By using, silica can be uniformly dispersed in the three components of isoprene-based rubber, butadiene rubber, and styrene-butadiene rubber, and stress concentration is suppressed and heat generation is reduced, resulting in high-speed resistance. It is thought that not only chipping performance but also low fuel consumption performance will be improved. Therefore, it is presumed that the rubber composition significantly improves the overall performance of fuel efficiency and chipping resistance at high speed.

(Rubber component)
The rubber composition contains isoprene-based rubber, styrene-butadiene rubber (SBR), and butadiene rubber (BR) as rubber components.

Examples of the isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, modified IR and the like. As the NR, for example, SIR20, RSS # 3, TSR20 and the like, which are common in the rubber industry, can be used. The IR is not particularly limited, and for example, IR2200 or the like, which is common in the rubber industry, can be used. Modified NR includes deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc., and modified NR includes epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. Examples of the 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.

When the rubber composition contains isoprene-based rubber, the content of isoprene-based rubber in 100% by mass of the rubber component is preferably 3% by mass or more, more preferably 5% by mass or more, still more preferably 7% by mass or more. .. The upper limit is preferably less than 50% by mass, more preferably 30% by mass or less, still more preferably 20% by mass or less, and particularly preferably 15% by mass or less. Within the above range, the overall performance of fuel efficiency and chipping resistance at high speed tends to be improved.

The SBR is not particularly limited, and for example, emulsion polymerization SBR (E-SBR), solution polymerization SBR (S-SBR), and the like, which are common in the tire industry, can be used. These may be used alone or in combination of two or more.

The weight average molecular weight (Mw) of SBR is preferably 200,000 or more, more preferably 600,000 or more, still more preferably 700,000 or more, and particularly preferably 700,000 or more, from the viewpoint of overall performance of fuel efficiency and chipping resistance at high speed. It is over 750,000. The upper limit is not particularly limited, but is preferably 1.5 million or less, more preferably 1.3 million or less, still more preferably 1.1 million or less, and particularly preferably 1 million or less.

The styrene content of SBR is preferably 20% by mass or more, more preferably 30% by mass or more, still more preferably 33% by mass or more, and particularly preferably 35% by mass or more. The styrene content is preferably 60% by mass or less, more preferably 50% by mass or less, still more preferably 45% by mass or less, and particularly preferably 43% by mass or less. Within the above range, the overall performance of fuel efficiency and chipping resistance at high speed tends to be improved.

The vinyl bond amount of SBR is preferably 20 mol% or more, more preferably 30 mol% or more, still more preferably 33 mol% or more, and particularly preferably 35 mol% or more. The vinyl bond amount is preferably 60 mol% or less, more preferably 50 mol% or less, still more preferably 45 mol% or less, and particularly preferably 43 mol% or less. Within the above range, the overall performance of fuel efficiency and chipping resistance at high speed tends to be improved.

In the present specification, the weight average molecular weight (Mw) is a gel permeation chromatograph (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL manufactured by Tosoh Corporation. It can be obtained by standard polystyrene conversion based on the measured value by SUPERMULTIPORE HZ-M). The styrene content can be measured by ^{1 1} H-NMR measurement. The vinyl bond amount (1,2-bonded butadiene unit amount) can be measured by infrared absorption spectrum analysis.

As the SBR, either an oil-extended styrene-butadiene copolymer or a non-oil-extended styrene-butadiene copolymer can be used, but among them, from the viewpoint of overall performance of low fuel consumption performance and chipping resistance at high speed. , Oil-extended styrene-butadiene copolymer can be preferably used.

The oil-extended styrene-butadiene copolymer is obtained by oil-expanding a styrene-butadiene copolymer using a stretched oil. As described above, by containing the oil-expanded styrene-butadiene copolymer previously oil-expanded with the stretched oil, the stretched oil and the filler in the rubber component are compared with the compounded rubber in which the oil is kneaded at the time of compounding the rubber composition. Dispersibility can be improved.

The oil-extended styrene-butadiene copolymer preferably has a branched structure introduced therein. The styrene-butadiene copolymer into which the branched structure is introduced is, for example, at least one polyfunctional coupling selected from the group consisting of an epoxy compound, a halogen-containing silicon compound, and an alkoxysilane compound at the polymer terminal. Examples thereof include those modified with an agent and those polymerized in the presence of a small amount of branching agent. Among these, those in which the polymer terminal is modified with a polyfunctional coupling agent are preferable.

The styrene-butadiene copolymer can be prepared by copolymerizing styrene and butadiene using, for example, a polymerization initiator. As the polymerization initiator, a lithium-based initiator is preferable. As the lithium-based initiator, an organic lithium compound is preferable. Examples of the organic lithium compound include alkyllithiums such as n-butyllithium, sec-butyllithium and t-butyllithium; alkylenedithiums such as 1,4-dilithiumbutane; phenyllithium, stillbenlithium and diisopropenylbenzenelithium. Examples thereof include alkyllithium such as butyllithium and aromatic hydrocarbon lithium such as a reactant such as divinylbenzene; lithium polynuclear hydrocarbon such as lithium naphthalene; aminolithium, tributyltin lithium and the like.

At the time of polymerization, if necessary, an ether compound, an amine or the like can be used as a styrene randomizing agent at the time of copolymerization and as an agent for adjusting the vinyl bond amount. Examples of the ether compound or amine include dimethoxybenzene, tetrahydrofuran, dimethoxyethane, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, triethylamine, pyridine, N-methylmorpholine, N, N, N', N'-tetramethylethylenediamine and dipiperidino. Etan and the like can be mentioned. Further, activators such as potassium dodecylbenzenesulfonate, potassium linoleate, potassium benzoate, potassium futalate, and potassium tetradecylbenzenesulfonate can also be used for the same purpose.

As the polymerization solvent, n-hexane, cyclohexane, heptane, benzene and the like can be used. The polymerization method may be either a batch polymerization method or a continuous polymerization method, but it is preferable to use the continuous polymerization method from the viewpoint that a styrene-butadiene copolymer having the above-mentioned various characteristics can be preferably obtained. As the polymerization condition, the polymerization temperature is usually 0 to 130 ° C., preferably 10 to 100 ° C. The polymerization time is usually 5 minutes to 24 hours, preferably 10 minutes to 10 hours. The monomer concentration in the polymerization solvent (total of monomers / (total of monomers + polymerization solvent)) is usually 5 to 50% by mass, preferably 10 to 35% by mass.

Generally, when a lithium-based initiator is used, the polymerization reaction rate of styrene and the polymerization reaction rate of butadiene are different. In addition, each polymerization reaction rate is affected by the polymerization temperature and the monomer concentration. Therefore, when a simple reaction is carried out, in the latter half of the reaction in which the polymerization temperature rises, a large amount of styrene reacts due to the influence of the polymerization temperature and the high concentration of the styrene monomer, and many styrene long chains are generated, resulting in a large number of styrene long chains. The content ratio of the chain may increase. Therefore, as a method for adjusting the content ratios of the styrene single chain and the styrene long chain to appropriate values, a method of controlling the polymerization temperature at a place where the reaction rates of styrene and butadiene become the same value, and a method of charging butadiene before the reaction are used. There is a method of increasing the amount of styrene taken up at the initial stage of polymerization by starting the reaction in a reduced state, and then continuously introducing the reduced amount of butadiene.

As a specific method for introducing a branched structure into the styrene-butadiene copolymer, when modified with a polyfunctional coupling agent, an active polymer having a lithium active terminal obtained by a batch polymerization method or a continuous polymerization method can be used. From the group consisting of halogen-containing silicon compounds such as silicon chloride, alkoxysilane compounds, alkoxysilane sulfide compounds, (poly) epoxy compounds, urea compounds, amide compounds, imide compounds, thiocarbonyl compounds, lactam compounds, ester compounds, and ketone compounds. A method of reacting with at least one selected polyfunctional coupling agent can be mentioned. Among these, halogen-containing silicon compounds such as silicon tetrachloride, alkoxysilane compounds, alkoxysilane sulfide compounds, and (poly) epoxy compounds are preferable, and halogen-containing silicon compounds, alkoxysilane compounds, and (poly) epoxy compounds are even more preferable. Further, in the case of polymerization in the presence of a small amount of branching agent, specific examples of the branching agent include divinylbenzene. The introduction amount is preferably 10% by mass or less with respect to 100% by mass of the styrene-butadiene copolymer.

Examples of the spreading oil used for oil spreading of the styrene-butadiene copolymer include naphthenic, paraffinic, aromatic oil spreading and the like. Examples of the oil spreading method include a method in which spreading oil is added after the completion of polymerization, and the solvent is removed and dried by a conventionally known method.

The amount of the spreading oil used is preferably 5 to 50 parts by mass, more preferably 10 to 40 parts by mass with respect to 100 parts by mass of the styrene-butadiene copolymer.

The SBR may be a non-modified SBR or a modified SBR. Further, as the SBR, a hydrogenated styrene-butadiene copolymer (hydrogenated SBR) can also be used.

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

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

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.

Regarding the content of SBR in 100% by mass of the rubber component, the content of SBR in 100% by mass of the rubber component is preferably 25% by mass or more, more preferably 35% by mass or more, still more preferably 45% by mass or more, particularly. It is preferably 50% by mass or more. The upper limit is preferably less than 80% by mass, more preferably 70% by mass or less, still more preferably 65% by mass or less, and particularly preferably 60% by mass or less. Within the above range, the overall performance of fuel efficiency and chipping resistance at high speed tends to be improved.

The BR is not particularly limited, and for example, a high cis BR having a high cis content, a BR containing syndiotactic polybutadiene crystals, a BR synthesized using a rare earth catalyst, and the like can be used. These may be used alone or in combination of two or more. Among them, the BR preferably contains a high cis BR having a cis content of 90% by mass or more. The cis content is more preferably 95% by mass or more. The cis content can be measured by infrared absorption spectrum analysis.

Further, the BR may be a non-modified BR or a modified BR. Examples of the modified BR include modified BR into which a functional group similar to that of modified SBR has been introduced. Further, as BR, a hydrogenated butadiene polymer (hydrogenated BR) can also be used.

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

The content of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 20% by mass or more, and further preferably 30% by mass or more. The upper limit is preferably less than 50% by mass, more preferably 45% by mass or less, still more preferably 40% by mass or less. Within the above range, the overall performance of fuel efficiency and chipping resistance at high speed tends to be improved.

As the rubber component that can be used in addition to the isoprene-based rubber, SBR, and BR, for example, other diene-based rubber can be used. Examples of other diene-based rubbers include styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). Further, butyl rubber, fluororubber and the like can also be mentioned. These may be used alone or in combination of two or more.

(silica)
Silica is blended in the rubber composition as a filler. Examples of the silica that can be used include dry silica (anhydrous silica) and wet silica (hydrous silica). Of these, wet silica is preferable because it has a large number of silanol groups. As commercially available products, products such as Degussa, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., and Tokuyama Corporation can be used. 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 50 m ² / g or more, more preferably 150 m ² / g or more, still more preferably 160 m ² / g or more, and particularly preferably 180 m ² / g or more. It may be 210 m ² / g or more. The upper limit of N ₂ SA of silica is not particularly limited, but is preferably 600 m ² / g or less, more preferably 350 m ² / g or less, and further preferably 260 m ² / g or less. Within the above range, the overall performance of fuel efficiency and chipping resistance at high speed tends to be improved.
The N ₂ SA of silica is a value measured by the BET method according to ASTM D3037-93.

The average primary particle size of silica is preferably less than 25 nm, more preferably less than 18 nm, still more preferably 16 nm or less, and particularly preferably 15 nm or less, from the viewpoint of overall performance of fuel efficiency and chipping resistance at high speed. The lower limit of the average primary particle diameter is not particularly limited, but is preferably 3 nm or more, more preferably 5 nm or more, and further preferably 7 nm or more. In particular, there is a tendency that a remarkable effect can be obtained by using silica and carbon black having an average primary particle diameter of less than 18 nm in combination. The average primary particle diameter can be determined by observing with a transmission type or scanning electron microscope, measuring 400 or more primary particles of silica observed in the visual field, and averaging them.

In the rubber composition, the content of silica is preferably 30 parts by mass or more, more preferably more than 50 parts by mass, still more preferably 60 parts by mass or more, and particularly preferably 65 parts by mass with respect to 100 parts by mass of the rubber component. It is more than a part. The upper limit of the content is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, still more preferably 100 parts by mass or less, and particularly preferably 90 parts by mass or less. Within the above range, the overall performance of fuel efficiency and chipping resistance at high speed tends to be improved.

（式中、ｘは、硫黄原子の平均個数を表し、３．５以上である。ｍは、６以上の整数を表す。Ｒ^１～Ｒ^６は、同一若しくは異なって炭素数１～６のアルキル基又はアルコキシ基を表し、Ｒ^１～Ｒ^３の少なくとも１つ及びＲ^４～Ｒ^６の少なくとも１つが前記アルコキシ基である。なお、Ｒ^１～Ｒ^６は、前記アルキル基又は前記アルコキシ基が結合した環構造を形成したものでもよい。） (Silane coupling agent)
The silane coupling agent used in the rubber composition contains an organosilicon compound containing an alkoxysilyl group and a sulfur atom and having 6 or more carbon atoms connecting the alkoxysilyl group and the sulfur atom. Such an organic silicon compound may be used alone or in combination of two or more. Among the organic silicon compounds, the organic silicon compound represented by the following average composition formula (I) is preferable.

(In the formula, x represents the average number of sulfur atoms and is 3.5 or more. M represents an integer of 6 or more. R ¹ to R ⁶ are alkyl having 1 to 6 carbon atoms which are the same or different. Representing a group or an alkoxy group, at least one of R ¹ to R ³ and at least one of R ⁴ to R ⁶ are the alkoxy groups. In R ¹ to R ⁶ , the alkyl group or the alkoxy group is bonded. It may be a ring structure formed.)

x represents the average number of sulfur atoms of the organic silicon compound. x is preferably 3.5 or more and 12 or less. Here, the average number of sulfur atoms and the number of silicon atoms are values obtained by measuring the amount of sulfur and the amount of silicon in the composition by fluorescent X-rays and converting them from their respective molecular weights.

m represents an integer of 6 or more, preferably 6 or more and 14 or less.

The number of carbon atoms of the alkyl group (R ¹ to R ⁶ ) is preferably 1 or more and 5 or less. The alkyl group may be linear, branched or cyclic. Specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an iso-butyl group, a sec-butyl group, a tert-butyl group and the like.

The alkoxy group (R ¹ to R ⁶ ) preferably has 1 or more and 5 or less carbon atoms. The hydrocarbon group in the alkoxy group may be linear, branched or cyclic. Specific examples thereof include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group and the like.

At least one of R ¹ to R ³ and at least one of R ⁴ to R ⁶ are alkoxy groups having 1 to 6 carbon atoms, and preferably two or more of each of R ¹ to R ³ and R ⁴ to R ⁶ are present. It is an alkoxy group having 1 to 6 carbon atoms.

In addition, R ¹ to R ⁶ may form a ring structure in which an alkyl group having 1 to 6 carbon atoms and an alkoxy group are bonded. For example, when (i) R ¹ forms a ring structure in which an ethoxy group and R ² are bonded to a methyl group, and (ii) R ¹ forms a ring structure in which an ethyl group and R ² are bonded to a methyl group, respectively. A structure in which a divalent group "-OC _{2 H 4-CH 2-" and "-C 2 H 4 - CH 2- "} are formed in ¹ and R ² and bonded to Si can be mentioned.

The organic silicon compound can be prepared, for example, by the production method described in JP-A-2018-65954. Specifically, by reacting the halogen group-containing organic silicon compound of the formula (I-1) described in JP-A _- 2018-65954, anhydrous sodium sulfide represented by Na 2S, and if necessary, sulfur. , The organic silicon compound can be produced. When performing the above reaction, the addition of sulfur is optional for the adjustment of the sulfide chain, and the compound of the average composition formula (I-1) and the anhydrous sodium sulfide are obtained so as to obtain the desired compound of the average composition formula (I). And if necessary, it may be determined from the blending amount with sulfur. For example, when it is desired to set x of the compound of the average composition formula (I) to 3.5, react 1.0 mol of anhydrous sodium sulfide, 2.5 mol of sulfur, and 2.0 mol of the compound of the formula (I-1). Just do it.

As described above, the uniformity of silica and rubber is important for improving the overall performance of low fuel consumption performance and chipping resistance at high speed, but alkoxysilyl groups and sulfur atoms are used as silane coupling agents. When an organic silicon compound containing an alkoxysilyl group and a sulfur atom having 6 or more carbon atoms, that is, a long-chain silane coupling agent is used, the alkoxy group in the compound reacts with the hydroxyl group on the silica surface. By doing so, the surface of the silica is made hydrophobic, and the influence of the hydrophobicity becomes larger than that of the conventional silane coupling agent due to the long carbon chain of the compound, so that the dispersibility of the silica is remarkably improved. Therefore, silica is uniformly dispersed in the three components of isoprene-based rubber, butadiene rubber, and styrene-butadiene rubber, suppressing stress concentration and reducing heat generation, resulting in not only high-speed chipping resistance but also low chipping resistance. Fuel performance is also improved. Therefore, by using such a long-chain silane coupling agent, the overall performance of fuel efficiency and chipping resistance at high speed can be remarkably improved.

In the rubber composition, the content of the organic silicon compound is preferably 0.1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, particularly preferably 5 parts by mass or more, based on 100 parts by mass of silica. Is 7 parts by mass or more. The upper limit of the content is preferably 50 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less. Within the above range, the overall performance of fuel efficiency and chipping resistance at high speed tends to be improved. It is desirable that the content of the organic silicon compound represented by the average composition formula (I) is in the same range.

The rubber composition may contain a silane coupling agent other than an organic silicon compound containing an alkoxysilyl group and a sulfur atom and having 6 or more carbon atoms connecting the alkoxysilyl group and the sulfur atom. ..
The other silane coupling agent is not particularly limited, and is, for example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, and bis (4-triethoxysilylbutyl) tetra. Sulfide, 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-trimethoxy) Cyrilethyl) disulfide, bis (4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyltetrasulfide, Sulfides such as 3-triethoxysilylpropylmethacrylate monosulfide, 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, Momentive's NXT, mercaptos such as NXT-Z, vinyltriethoxysilane, Vinyl type such as vinyltrimethoxysilane, amino type such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, etc. Examples thereof include glycidoxy-based, nitro-based such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane, and chloro-based such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. As commercially available products, products such as Degussa, Momentive, Shinetsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., Toray Dow Corning Co., Ltd. and the like can be used. These may be used alone or in combination of two or more.

In the rubber composition, the content of the silane coupling agent (total amount of the organic silicon compound and other silane coupling agents) is preferably 0.1 part by mass or more, more preferably 0.1 part by mass with respect to 100 parts by mass of silica. It is 3 parts by mass or more, more preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more. The upper limit of the content is preferably 50 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less. Within the above range, the overall performance of fuel efficiency and chipping resistance at high speed tends to be improved.

(Other fillers)
The filler other than silica is not particularly limited, and materials known in the rubber field can be used, and inorganic fillers such as carbon black, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, and mica can be used. And so on. Of these, carbon black is preferable.

In the rubber composition, the content of the filler (total content of the filler) is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, still more preferably 80 parts by mass with respect to 100 parts by mass of the rubber component. The amount is 90 parts or more, particularly preferably 90 parts by mass or more. The upper limit of the content is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, still more preferably 130 parts by mass or less, and particularly preferably 110 parts by mass or less. Within the above range, the overall performance of fuel efficiency and chipping resistance at high speed tends to be improved.

In the rubber composition, the silica content in 100% by mass of the filler is preferably 50% by mass or more, preferably 65% by mass or more, and 70% by mass from the viewpoint of overall performance of fuel efficiency and chipping resistance at high speed. % Or more is more preferable, and 75% by mass or more is particularly preferable. The upper limit is not particularly limited, but is preferably 95% by mass or less, more preferably 90% by mass or less, and further preferably 85% by mass or less.

The carbon black that can be used in the rubber composition is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. As commercial products, products such as Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin Nikka Carbon Co., Ltd., Columbia Carbon Co., Ltd. are used. can. 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 50 m ² / g or more, more preferably 100 m ² / g or more, further preferably 120 m ² / g or more, and particularly preferably 135 m ² / g or more. The N ₂ SA is preferably 250 m ² / g or less, more preferably 200 m ² / g or less, further preferably 160 m ² / g or less, and particularly preferably 150 m ² / g or less. Within the above range, the overall performance of fuel efficiency and chipping resistance at high speed tends to be improved.
The nitrogen adsorption specific surface area of carbon black is determined by JIS K6217-2: 2001.

In the rubber composition, the content of carbon black is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and further preferably 15 parts by mass or more with respect to 100 parts by mass of the rubber component. The upper limit of the content is preferably 80 parts by mass or less, more preferably 50 parts by mass or less, still more preferably 35 parts by mass or less, and particularly preferably 25 parts by mass or less. Within the above range, the overall performance of fuel efficiency and chipping resistance at high speed tends to be improved.

The rubber composition contains isoprene-based rubber (% by mass) and styrene-butadiene rubber (% by mass) in 100% by mass of the rubber component from the viewpoint of overall performance of low fuel consumption and chipping resistance at high speed. It is desirable that the content (% by mass) of the butadiene rubber satisfies the following formulas (1) and (2).
(1) Content of isoprene-based rubber <Content of styrene-butadiene rubber (2) Content of butadiene rubber <Content of styrene-butadiene rubber

The rubber composition contains styrene-butadiene rubber (mass%) and isoprene-based rubber (% by mass) in 100% by mass of the rubber component from the viewpoint of overall performance of low fuel consumption and chipping resistance at high speed. However, it is desirable to satisfy the following formula.
10% by mass ≤ content of styrene-butadiene rubber-content of isoprene-based rubber ≤ 70% by mass
Content of styrene-butadiene rubber-The content of isoprene-based rubber is preferably 15% by mass or more, more preferably 30% by mass or more, still more preferably 40% by mass or more. The upper limit is preferably 60% by mass or less, more preferably 55% by mass or less, still more preferably 50% by mass or less.

The rubber composition has a styrene-butadiene rubber content (mass%) and a butadiene rubber content (mass%) in 100% by mass of the rubber component from the viewpoint of overall performance of low fuel consumption performance and high-speed chipping resistance. , It is desirable to satisfy the following formula.
1% by mass ≤ content of styrene-butadiene rubber-content of butadiene rubber ≤ 50% by mass
Content of styrene-butadiene rubber-The content of butadiene rubber is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more. The upper limit is preferably 40% by mass or less, more preferably 30% by mass or less, still more preferably 25% by mass or less.

From the viewpoint of overall performance of low fuel consumption performance and chipping resistance at high speed, the rubber composition has an isoprene-based rubber content (mass%) and a butadiene rubber content (mass%) in 100% by mass of the rubber component. It is desirable that the content of silica (parts by mass) and the content of carbon black (parts by mass) with respect to 100 parts by mass of the rubber component satisfy the following formula (3).
(3) | Isoprene-based rubber content-butadiene rubber content | << | Silica content-Carbon black content |

The rubber composition has an isoprene-based rubber content (mass%) and a butadiene rubber content (mass%) in 100% by mass of the rubber component from the viewpoint of overall performance of low fuel consumption performance and high-speed chipping resistance. , It is desirable to satisfy the following formula.
5% by mass ≤ | Isoprene-based rubber content-butadiene rubber content | ≤50% by mass
| Content of isoprene-based rubber-Content of butadiene rubber | is preferably 15% by mass or more, more preferably 20% by mass or more, still more preferably 22% by mass or more. The upper limit is preferably 40% by mass or less, more preferably 35% by mass or less, still more preferably 30% by mass or less. From the viewpoint of overall performance of fuel efficiency and chipping resistance at high speed, it is desirable that the content of isoprene-based rubber <the content of butadiene rubber.

From the viewpoint of overall performance of fuel efficiency and chipping resistance at high speed, the rubber composition has the following formulas for the silica content (mass part) and carbon black content (mass part) with respect to 100 parts by mass of the rubber component. It is desirable to meet.
15 parts by mass ≤ | silica content-carbon black content | ≤80 parts by mass | silica content-carbon black content | is preferably 25 parts by mass or more, more preferably 35 parts by mass or more, and 40. More than parts by mass is more preferable. The upper limit is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, and further preferably 55 parts by mass or less. From the viewpoint of overall performance of fuel efficiency and chipping resistance at high speed, carbon black content <silica content is desirable.

(Plasticizer)
A plasticizer may be added to the rubber composition. A plasticizer is a material that imparts plasticity to a rubber component, and is, for example, a liquid plasticizer (a plasticizer in a liquid state at room temperature (25 ° C.)) or a resin (a resin in a solid state at room temperature (normal temperature (25 ° C.))). And so on.

In the rubber composition, the content of the plasticizer (total amount of the plasticizer) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, still more preferably 12 parts by mass or more with respect to 100 parts by mass of the rubber component. Is. The upper limit of the content is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, still more preferably 30 parts by mass or less, and particularly preferably 20 parts by mass or less. Within the above range, the overall performance of fuel efficiency and chipping resistance at high speed tends to be improved.

The liquid plasticizer (plasticizer in a liquid state at room temperature (25 ° C.)) that can be used in the rubber composition is not particularly limited, and is an oil or a liquid polymer (liquid resin, liquid diene polymer, liquid farnesene polymer, etc.). And so on. These may be used alone or in combination of two or more.

In the rubber composition, the content of the liquid plasticizer is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and further preferably 12 parts by mass or more with respect to 100 parts by mass of the rubber component. The upper limit of the content is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, still more preferably 30 parts by mass or less, and particularly preferably 20 parts by mass or less. Within the above range, the overall performance of fuel efficiency and chipping resistance at high speed tends to be improved.

Examples of the oil include process oils, vegetable oils, or mixtures thereof. As the process oil, for example, a paraffin-based process oil, an aroma-based process oil, a naphthenic process oil, or the like can be used. Vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut oil, rosin, pine oil, pineapple, tall oil, corn oil, rice oil, beni flower oil, sesame oil, and olive oil. , Sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, tung oil and the like. Commercial products include Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Co., Ltd., Orisoi Co., Ltd., H & R Co., Ltd., Toyokuni Seiyu Co., Ltd., Showa Shell Sekiyu Co., Ltd., Fuji Kosan Co., Ltd., Products such as Nisshin Oillio Group Co., Ltd. can be used. Of these, process oils (paraffin-based process oils, aroma-based process oils, naphthen-based process oils, etc.) and vegetable oils are preferable.

In the rubber composition, the oil content is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and further preferably 12 parts by mass or more with respect to 100 parts by mass of the rubber component. The upper limit of the content is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, still more preferably 30 parts by mass or less, and particularly preferably 20 parts by mass or less. Within the above range, the overall performance of fuel efficiency and chipping resistance at high speed tends to be improved.
The oil content also includes the oil contained in the oil spread oil.

The liquid resin includes terpene resin (including terpene phenol resin and aromatic modified terpene resin), rosin resin, styrene resin, C5 resin, C9 resin, C5 / C9 resin, and di, which are in a liquid state at 25 ° C. Cyclopentadiene (DCPD) resin, kumaron inden resin (including kumaron and inden simple resin), phenol resin, olefin resin, polyurethane resin, acrylic resin and the like can be mentioned. In addition, these hydrogenated additives can also be used.

In the rubber composition, the content of the liquid resin is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and further preferably 12 parts by mass or more with respect to 100 parts by mass of the rubber component. The upper limit of the content is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, still more preferably 30 parts by mass or less, and particularly preferably 20 parts by mass or less. Within the above range, the overall performance of fuel efficiency and chipping resistance at high speed tends to be improved.

Examples of the liquid diene polymer include a liquid styrene butadiene copolymer (liquid SBR), a liquid butadiene polymer (liquid BR), a liquid isoprene polymer (liquid IR), and a liquid styrene isoprene copolymer (liquid) in a liquid state at 25 ° C. SIR), liquid styrene butadiene styrene block copolymer (liquid SBS block polymer), liquid styrene isoprene styrene block copolymer (liquid SIS block polymer), liquid farnesene polymer, liquid farnesene butadiene copolymer and the like. .. These may have the terminal or main chain denatured with a polar group. In addition, these hydrogenated additives can also be used.

In the rubber composition, the content of the liquid diene polymer is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and further preferably 12 parts by mass or more. The upper limit of the content is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, still more preferably 30 parts by mass or less, and particularly preferably 20 parts by mass or less. Within the above range, the overall performance of fuel efficiency and chipping resistance at high speed tends to be improved.

The liquid farnesene-based polymer is a polymer obtained by polymerizing farnesene, and has a structural unit based on farnesene. Farnesene includes α-farnesene ((3E, 7E) -3,7,11-trimethyl-1,3,6,10-dodecatetraene) and β-farnesene (7,11-dimethyl-3-methylene-1). , 6,10-Dodecatorien) and the like are present, but (E) -β-farnesene having the following structure is preferable.

The liquid farnesene-based polymer may be a homopolymer of farnesene (farnesene homopolymer) or a copolymer of farnesene and a vinyl monomer (farnesene-vinyl monomer copolymer).

Examples of vinyl monomers include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-tert-butylstyrene, 5-. t-butyl-2-methylstyrene, vinylethylbenzene, divinylbenzene, trivinylbenzene, divinylnaphthalene, tert-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl) dimethylaminoethyl ether, N, N-dimethylaminoethyl Styrene, N, N-dimethylaminomethyl styrene, 2-ethyl styrene, 3-ethyl styrene, 4-ethyl styrene, 2-t-butyl styrene, 3-t-butyl styrene, 4-t-butyl styrene, vinyl xylene, Examples thereof include aromatic vinyl compounds such as vinylnaphthalene, vinyltoluene, vinylpyridine, diphenylethylene, tertiary amino group-containing diphenylethylene, and conjugated diene compounds such as butadiene and isoprene. These may be used alone or in combination of two or more. Of these, butadiene is preferable. That is, as the farnesene-vinyl monomer copolymer, a copolymer of farnesene and butadiene (farnesene-butadiene copolymer) is preferable.

In the farnesene-vinyl monomer copolymer, the mass-based copolymerization ratio (farnesene / vinyl monomer) of farnesene and the vinyl monomer is preferably 40/60 to 90/10.

As the liquid farnesene-based polymer, one having a weight average molecular weight (Mw) of 3,000 to 300,000 can be preferably used. The Mw of the liquid farnesene polymer is preferably 8,000 or more, more preferably 10,000 or more, and preferably 100,000 or less, more preferably 60,000 or less, still more preferably 50,000 or less.

In the rubber composition, the content of the liquid farnesene polymer is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and further preferably 12 parts by mass or more with respect to 100 parts by mass of the rubber component. The upper limit of the content is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, still more preferably 30 parts by mass or less, and particularly preferably 20 parts by mass or less. Within the above range, the overall performance of fuel efficiency and chipping resistance at high speed tends to be improved.

Examples of the resin (resin in a solid state at room temperature (25 ° C.)) that can be used in the rubber composition include aromatic vinyl polymers in a solid state at room temperature (25 ° C.), kumaron inden resin, and kumaron resin. Examples thereof include inden resin, phenol resin, rosin resin, petroleum resin, terpene resin, and acrylic resin. Further, the resin may be hydrogenated. These may be used alone or in combination of two or more. Among them, aromatic vinyl polymers, petroleum resins, and terpene-based resins are preferable from the viewpoint of durability of the total performance of low fuel consumption performance and high-speed chipping resistance.

When the rubber composition contains the resin (resin in a solid state at room temperature (25 ° C.)), the content thereof is preferably 1 part by mass or more, more preferably 3 parts by mass with respect to 100 parts by mass of the rubber component. More than parts, more preferably 5 parts by mass or more. The upper limit of the content is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, further preferably 30 parts by mass or less, particularly preferably 20 parts by mass or less, and may be 10 parts by mass or less. Within the above range, the overall performance of fuel efficiency and chipping resistance at high speed tends to be improved. The contents of the aromatic vinyl polymer, petroleum resin, and terpene resin are preferably in the same range.

The softening point of the resin is preferably 60 ° C. or higher, more preferably 70 ° C. or higher, and even more preferably 80 ° C. or higher. The upper limit is preferably 160 ° C. or lower, more preferably 130 ° C. or lower, and even more preferably 115 ° C. or lower. By keeping it within the above range, there is a tendency that good overall performance of fuel efficiency and chipping resistance at high speed can be obtained.
The softening point of the resin is the temperature at which the ball drops when the softening point defined in JIS K6220-1: 2001 is measured by a ring-ball type softening point measuring device.

The aromatic vinyl polymer is a polymer containing an aromatic vinyl monomer as a constituent unit. For example, a resin obtained by polymerizing α-methylstyrene and / or styrene can be mentioned. Specifically, a homopolymer of styrene (styrene resin) and a homopolymer of α-methylstyrene (α-methylstyrene resin) can be mentioned. ), Polymers of α-methylstyrene and styrene, copolymers of styrene and other monomers, and the like.

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

The kumaron resin is a resin containing kumaron as a main monomer component constituting the skeleton (main chain) of the resin.

The indene resin is a resin containing indene as a main monomer component constituting the skeleton (main chain) of the resin.

As the phenol resin, for example, a known polymer such as a polymer obtained by reacting phenol with aldehydes such as formaldehyde, acetaldehyde, and furfural with an acid or an alkali catalyst can be used. Among them, those obtained by reacting with an acid catalyst (novolak type phenol resin or the like) are preferable.

Examples of the rosin resin include natural rosins, polymerized rosins, modified rosins, ester compounds thereof, and rosin-based resins typified by hydrogen additives thereof.

Examples of the petroleum resin include C5 resin, C9 resin, C5 / C9 resin, dicyclopentadiene (DCPD) resin, hydrogenated substances thereof and the like.

The terpene-based resin is a polymer containing terpene as a constituent unit, and examples thereof include a polyterpene resin obtained by polymerizing a terpene compound, an aromatic-modified terpene resin obtained by polymerizing a terpene compound and an aromatic compound, and the like. Be done. In addition, these hydrogenated additives can also be used.

The polyterpene resin is a resin obtained by polymerizing a terpene compound. The terpene compound is a hydrocarbon having a composition of (C ₅ H ₈ ) _n and an oxygen-containing derivative thereof, and is a mono terpene (C ₁₀ H ₁₆ ), a sesqui terpene (C ₁₅ H ₂₄ ), and a diterpene (C ₂₀ H). It is a compound having a terpene as a basic skeleton classified into ₃₂ ) and the like. Examples thereof include terpinene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol and the like.

Examples of the polyterpene resin include pinene resin, limonene resin, dipentene resin, pinene / limonene resin and the like made from the above-mentioned terpene compound. Of these, pinene resin is preferable. The pinene resin usually contains both α-pinene and β-pinene having an isomer relationship, but due to the difference in the contained components, β-pinene resin containing β-pinene as a main component and α- It is classified as α-pinene resin containing pinene as the main component.

Examples of the aromatic-modified terpene resin include terpene phenol resins made from the terpene compounds and phenolic compounds, and terpene styrene resins made from the terpene compounds and styrene compounds. Further, a terpene phenol styrene resin made from the above-mentioned terpene compound, phenol-based compound and styrene-based compound can also be used. Examples of the phenolic compound include phenol, bisphenol A, cresol, xylenol and the like. Moreover, styrene, α-methylstyrene and the like can be mentioned as a styrene compound.

The acrylic resin is a polymer containing an acrylic monomer as a constituent unit. For example, a styrene acrylic resin such as a styrene acrylic resin which has a carboxyl group and is obtained by copolymerizing an aromatic vinyl monomer component and an acrylic monomer component can be mentioned. Among them, a solvent-free carboxyl group-containing styrene acrylic resin can be preferably used.

The solvent-free carboxyl group-containing styrene acrylic resin is a high-temperature continuous polymerization method (high-temperature continuous lump polymerization method) (US patent) without using polymerization initiators, chain transfer agents, organic solvents, etc. as auxiliary raw materials as much as possible. 4,414,370, JP-A-59-6207, JP-A-5-58805, JP-A 1-313522, US Pat. No. 5,010,166, Toa Synthetic Research It is a (meth) acrylic resin (polymer) synthesized by the method described in the annual report TREND2000 No. 3, p42-45 and the like. In addition, in this specification, (meth) acrylic means methacrylic and acrylic.

Examples of the acrylic monomer component constituting the acrylic resin include (meth) acrylic acid, (meth) acrylic acid ester (alkyl ester such as 2 ethylhexyl acrylate, aryl ester, aralkyl ester, etc.), and (meth) acrylamide. , (Meta) acrylic acid derivatives such as (meth) acrylamide derivatives. In addition, (meth) acrylic acid is a general term for acrylic acid and methacrylic acid.

Examples of the aromatic vinyl monomer component constituting the acrylic resin include aromatic vinyls such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinylnaphthalene.

Further, as the monomer component constituting the acrylic resin, other monomer components may be used together with (meth) acrylic acid, a (meth) acrylic acid derivative, and aromatic vinyl.

Examples of the plasticizer include Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Toso Co., Ltd., Rutgers Chemicals Co., Ltd., BASF Co., Ltd., Arizona Chemical Co., Ltd., Nikko Chemical Co., Ltd., ( Products such as Nippon Shokubai Co., Ltd., ENEOS Co., Ltd., Arakawa Chemical Industry Co., Ltd., and Taoka Chemical Industry Co., Ltd. can be used.

(Other materials)
The rubber composition preferably contains an antiaging agent from the viewpoint of crack resistance, ozone resistance and the like.

The antiaging agent is not particularly limited, but is a naphthylamine-based antiaging agent such as phenyl-α-naphthylamine; a diphenylamine-based antiaging agent such as octylated diphenylamine and 4,4'-bis (α, α'-dimethylbenzyl) diphenylamine. N-isopropyl-N'-phenyl-p-phenylenediamine, N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, N, N'-di-2-naphthyl-p-phenylene P-phenylenediamine-based antioxidants such as diamine; quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinolin; 2,6-di-t-butyl-4-methyl Monophenolic anti-aging agents such as phenol and styrenated phenol; tetrakis- [methylene-3- (3', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] bis, tris, polyphenols such as methane Examples include anti-aging agents. Of these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferable, and N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1 are preferable. , 2-Dihydroquinoline polymers are more preferred. As commercially available products, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexis Co., Ltd. and the like can be used.

In the rubber composition, the content of the antiaging agent is preferably 0.2 parts by mass or more, and more preferably 0.5 parts by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 7.0 parts by mass or less, more preferably 4.0 parts by mass or less.

The rubber composition preferably contains stearic acid. In the rubber composition, the content of stearic acid is preferably 0.5 to 10 parts by mass, more preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the rubber component.

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

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

As the zinc oxide, conventionally known zinc oxide can be used, for example, Mitsui Metal Mining Co., Ltd., Toho Zinc Co., Ltd., HakusuiTech Co., Ltd., Shodo Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. Products can be used.

Wax may be added to the rubber composition. In the rubber composition, the content of the wax is preferably 0.5 to 10 parts by mass, and more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the rubber component.

The wax is not particularly limited, and examples thereof include petroleum wax, natural wax, and synthetic wax obtained by purifying or chemically treating a plurality of waxes. These waxes may be used alone or in combination of two or more.

Examples of petroleum-based waxes include paraffin wax and microcrystalline wax. The natural wax is not particularly limited as long as it is a wax derived from non-petroleum resources, and is, for example, a plant wax such as candelilla wax, carnauba wax, wood wax, rice wax, jojoba wax; Animal waxes; mineral waxes such as ozokerite, selecin, petrolactam; and purified products thereof. As commercially available products, for example, products such as Ouchi Shinko Kagaku Kogyo Co., Ltd., Nippon Seiro Co., Ltd., and Seiko Kagaku Co., Ltd. can be used.

It is preferable to add sulfur to the rubber composition from the viewpoint of forming an appropriate crosslinked chain on the polymer chain and imparting good performance.

In the rubber composition, the sulfur content is preferably 0.1 part by mass or more, more preferably 0.3 part by mass or more, still more preferably 0.5 part by mass or more with respect to 100 parts by mass of the rubber component. be. The content is preferably 4.0 parts by mass or less, more preferably 3.0 parts by mass or less, and further preferably 2.0 parts by mass or less.

Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur commonly used in the rubber industry. As commercial products, products such as Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Kasei Industry Co., Ltd., Flexis Co., Ltd., Nippon Inui Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

The rubber composition preferably contains a vulcanization accelerator.
In the rubber composition, the content of the vulcanization accelerator is not particularly limited and may be freely determined according to the desired vulcanization rate and crosslinking density, but is preferably 0 with respect to 100 parts by mass of the rubber component. It is 5.5 parts by mass or more, more preferably 1.0 part by mass or more, and further preferably 1.5 parts by mass or more. The upper limit is preferably 8.0 parts by mass or less, more preferably 6.0 parts by mass or less, and further preferably 5.0 parts by mass or less.

The type of vulcanization accelerator is not particularly limited, and a commonly used one can be used. Examples of the vulcanization accelerator include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiadylsulfenamide; tetramethylthiuram disulfide (TMTD). ), Tetrabenzyltiuram disulfide (TBzTD), tetrakis (2-ethylhexyl) thiuram disulfide (TOT-N) and other thiuram-based vulcanization accelerators; N-cyclohexyl-2-benzothiazolesulfenamide, Nt-butyl- 2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N, N'-diisopropyl-2-benzothiazolesulfenamide, etc. Sulfenamide-based vulcanization accelerator; guanidine-based vulcanization accelerators such as diphenylguanidine, dioltotrilguanidine, orthotrilviguanidine can be mentioned. These may be used alone or in combination of two or more. Of these, sulfenamide-based, guanidine-based, and benzothiazole-based vulcanization accelerators are preferable.

In addition to the components, a compounding agent generally used in the tire industry, for example, a material such as a mold release agent may be appropriately added to the rubber composition.

As a method for producing the rubber composition, a known method can be used. For example, each component can be kneaded using a rubber kneading device such as an open roll or a Banbury mixer, and then vulcanized. ..

As the kneading conditions, in the base kneading step of kneading additives other than the vulcanizing agent and the vulcanization accelerator, the kneading temperature is usually 50 to 200 ° C., preferably 80 to 190 ° C., and the kneading time is usually 30. Seconds to 30 minutes, preferably 1 minute to 30 minutes. In the finish kneading step of kneading the vulcanizing agent and the vulcanization accelerator, the kneading temperature is usually 100 ° C. or lower, preferably room temperature to 80 ° C. Further, the composition in which the vulcanizing agent and the vulcanization accelerator are kneaded is usually subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 120 to 200 ° C, preferably 140 to 180 ° C.

Members to which the rubber composition can be applied include treads (cap treads), sidewalls, base treads, bead apex, clinch apex, inner liners, under treads, breaker toppings, bright toppings, treads, and the like for pneumatic tires. It can be suitably used for each member. Among them, it can be suitably used for treads (cap treads).

Tires are manufactured by conventional methods using rubber compositions. That is, the rubber composition containing the above components is extruded according to the shape of a tread or the like at the unvulcanized stage, and is molded together with other tire members on a tire molding machine by a normal method. Form a vulcanized tire. A tire can be obtained by heating and pressurizing this unvulcanized tire in a vulcanizer.

Examples of the tire include a pneumatic tire and a non-pneumatic tire. Of these, pneumatic tires are preferable. Tires include passenger car tires, large passenger car tires, SUV (multipurpose sports car) tires, pickup vehicle tires, heavy load tires such as trucks and buses, light truck tires, two-wheeled vehicle tires, and winter tires (studless tires, Snow tires, stud tires), all-season tires, run-flat tires, aircraft tires, mining tires, competition tires, etc. Of these, tires for passenger cars, SUVs (sport utility vehicles), and pickup vehicles are preferable. For example, it can be realized as a summer tire or an all-season tire for these vehicles.

The present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.

Hereinafter, various chemicals used in Examples and Comparative Examples will be collectively described.
NR: TSR20
SBR1: JSR1502 manufactured by JSR Corporation (E-SBR, styrene content 23.5% by mass)
SBR2: Modified solution polymerization SBR produced in Production Example 1 below (styrene content 38% by mass, vinyl bond amount 39 mol%, Mw 800,000, oil expanded product in which 25 parts by mass of oil is added to 100 parts by mass of SBR).
BR: Nipol BR1220 manufactured by Nippon Zeon Co., Ltd. (BR obtained by polymerizing butadiene in the presence of a cobalt-based catalyst, cis 1,4 bond content 96%, Tg-105 ° C, Mw 460,000)
Carbon black: VULCAN10H (N134, _N2 SA144m ² / g) manufactured by Cabot Japan Co., Ltd.
Silica 1: Ultrasil 9100GR manufactured by Evonik Degussa (N ₂ SA230m ² / g, average primary particle diameter 15nm)
Silica 2: Ultrasil VN3 manufactured by Evonik Degussa (N ₂ SA175m ² / g, average primary particle diameter 18nm)
Organic silicon compound 1: Silane coupling agent synthesized in Production Example 2 below Organic silicon compound 2: Si266 (bis (3-triethoxysilylpropyl) disulfide) manufactured by Ebony Degussa.
Oil: VivaTec400 (TDAE oil) manufactured by H & R
Wax: Ozo Ace 0355 manufactured by Nippon Seiro Co., Ltd.
Anti-aging agent: Antigen 6C (N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd.
Stearic acid: Beads made by Nichiyu Co., Ltd. Tsubaki Zinc oxide: Zinc oxide manufactured by Mitsui Metal Mining Co., Ltd. Sulfur: Karuizawa Sulfur Co., Ltd. powdered sulfur vulcanization accelerator 1: Ouchi Shinko Kagaku Noxeller CZ (N-cyclohexyl-2-benzothiazolylsulfenamide) manufactured by Kogyo Co., Ltd.
Vulcanization accelerator 2: Noxeller D (N, N'-diphenylguanidine) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.

(Production Example 1: Synthesis of SBR2)
Two autoclaves with an inlet at the bottom and an outlet at the head, a stirrer and a jacket are connected in series as a reactor (internal volume 10 L), and butadiene, styrene, and cyclohexane are each connected in a predetermined ratio under a nitrogen atmosphere. Mixed in. This mixed solution is mixed with n-butyllithium in a static mixer to remove impurities via a dehydration column filled with active alumina, and then continuously supplied from the bottom of the first reactor, and further. 2,2-Bis (2-oxolanyl) propane as a polar substance and n-butyllithium as a polymerization initiator are continuously supplied from the bottom of the first reactor at a predetermined rate, and the temperature inside the reactor is 95. It was kept at ° C. The polymer solution was continuously withdrawn from the reactor head and supplied to the second reactor. Keep the temperature of the second reactor at 95 ° C., and use a mixture of tetraglycidyl-1,3-bisaminomethylcyclohexane (monomer) and the oligomer component as a denaturant at a predetermined rate in a 1000-fold diluted solution of cyclohexane. Was added continuously, and a denaturing reaction was carried out. The polymer solution was continuously withdrawn from the reactor and 2,6-di-tert-butyl-p-cresol was continuously added with a static mixer. Next, 25 parts by mass of extended oil (NC-140 manufactured by JX Nippon Oil Energy Co., Ltd.) was added to 100 parts by mass of the polymer, the solvent was removed by steam stripping, and the temperature was adjusted to 110 ° C. It was dried by a hot roll to obtain SBR2.

(Production Example 2: Synthesis of Organic Silicon Compound 1)
78.0 g (1.0 mol) of anhydrous soda, 80.3 g (2.5 mol) of sulfur and 480 g of ethanol were placed in a 2 L separable flask equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer. It was heated to 80 ° C. 566 g (2.0 mol) of 6-chlorohexyltriethoxysilane was added dropwise thereto, and the mixture was heated and stirred at 80 ° C. for 10 hours. This reaction solution was pressure-filtered using a filter plate to obtain a filtrate from which the salt produced as the reaction proceeded was removed. The obtained filtrate was heated to 100 ° C. and ethanol was distilled off under a reduced pressure of 10 mmHg or less to obtain an organic silicon compound 1 (silane coupling agent) as a reaction product. The obtained organic silicon compound 1 has an amount of sulfur contained in the compound of 18.5% by mass, and the average number of sulfur atoms X contained in one molecule of the organic silicon compound is 3.5, which is m. The value was 6.

<Examples and comparative examples>
According to the formulation shown in Table 1, a 1.7 L Banbury mixer is used to knead the ingredients other than sulfur and the vulcanization accelerator for 5 minutes until the discharge temperature reaches 170 ° C. to obtain a kneaded product. rice field. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and the mixture was kneaded for 4 minutes using a twin-screw open roll until the temperature reached 105 ° C. to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition is formed into a tread shape and bonded together with other tire members to form an unvulcanized tire, which is press-vulcanized for 12 minutes under the condition of 170 ° C. for a test tire (multipurpose). Tires for sports cars (tires for SUV), size P265 / 65R17 110S) were manufactured.

The obtained test tires were evaluated as follows. The evaluation results are shown in the table. In Table 1, Comparative Example 3 was used as a reference comparative example.

<Fuel efficiency performance>
Using a rolling resistance tester, measure the rolling resistance when each test tire is run at a rim of 15 x 6JJ, an internal pressure of 230 kPa, a load of 3.43 kN, and a speed of 80 km / h. The index was displayed as 100. The larger the value, the smaller the rolling resistance and the better the fuel efficiency.

<Chiping resistance at high speed>
Each test tire was incorporated into a regular rim, filled with air to the regular internal pressure, and then mounted on a vehicle to run on rough terrain at a speed of 70 km / hour for 4 hours. After running, rubber chips of 2 mm or more generated on the tire surface were counted, the number of chippings was calculated for each tire, and the chipping resistance index at high speed was calculated by the following formula. The larger the value, the less rubber is chipped and the better the chipping resistance at high speed.
(High-speed chipping resistance index) = (Number of chipping in standard comparison example) / (Number of chipping of each test tire) x 100

From the table, the number of carbon atoms containing isoprene-based rubber, butadiene rubber, styrene-butadiene rubber, silica, alkoxysilyl group and sulfur atom, and connecting the alkoxysilyl group and sulfur atom is 6 or more. An example including a silane coupling agent containing an organic silicon compound is the total performance of fuel efficiency and chipping resistance at high speed (expressed as the sum of two indices of fuel efficiency and chipping resistance at high speed). Was excellent.

Claims (13)

It contains a rubber component containing isoprene-based rubber, butadiene rubber and styrene-butadiene rubber, silica, and a silane coupling agent.
The silane coupling agent is a rubber composition for a tire containing an organosilicon compound containing an alkoxysilyl group and a sulfur atom and having 6 or more carbon atoms connecting the alkoxysilyl group and the sulfur atom. The rubber composition for a tire according to claim 1, wherein the content of isoprene-based rubber in 100% by mass of the rubber component is less than 50% by mass. The rubber composition for a tire according to claim 1 or 2, wherein the content of butadiene rubber in 100% by mass of the rubber component is less than 50% by mass. The rubber composition for a tire according to any one of claims 1 to 3, wherein the content of styrene-butadiene rubber in 100% by mass of the rubber component is less than 80% by mass. The rubber composition for a tire according to any one of claims 1 to 4, wherein the content of silica with respect to 100 parts by mass of the rubber component exceeds 50 parts by mass. The rubber composition for a tire according to any one of claims 1 to 5, which comprises silica having an average primary particle diameter of less than 18 nm. Also contains carbon black,
Claim 1 in which the content of isoprene-based rubber, styrene-butadiene rubber and butadiene rubber in 100% by mass of the rubber component and the content of silica and carbon black with respect to 100 parts by mass of the rubber component satisfy the following formulas (1) to (3). The rubber composition for a tire according to any one of 6 to 6.
(1) Isoprene-based rubber content <Styrene-butadiene rubber content (2) butadiene rubber content <Styrene-butadiene rubber content (3) | Isoprene-based rubber content-butadiene rubber content | Silica content-Carbon black content | The rubber composition for a tire according to any one of claims 1 to 7, wherein the content of styrene-butadiene rubber and isoprene-based rubber in 100% by mass of the rubber component satisfies the following formula.
10% by mass ≤ content of styrene-butadiene rubber-content of isoprene-based rubber ≤ 70% by mass The rubber composition for a tire according to any one of claims 1 to 8, wherein the content of styrene-butadiene rubber and butadiene rubber in 100% by mass of the rubber component satisfies the following formula.
1% by mass ≤ content of styrene-butadiene rubber-content of butadiene rubber ≤ 50% by mass The rubber composition for a tire according to any one of claims 1 to 9, wherein the content of isoprene-based rubber and butadiene rubber in 100% by mass of the rubber component satisfies the following formula.
5% by mass ≤ | Isoprene-based rubber content-butadiene rubber content | ≤50% by mass The rubber composition for a tire according to any one of claims 1 to 10, wherein the content of silica and carbon black with respect to 100 parts by mass of the rubber component satisfies the following formula.
15 parts by mass ≤ | Silica content-Carbon black content | ≤ 80 parts by mass The rubber composition for a tire according to any one of claims 1 to 11, which comprises silica having an average primary particle diameter of less than 18 nm and carbon black. A tire having a tire member made of the rubber composition according to any one of claims 1 to 12.