JP6436734B2 - Pneumatic tire - Google Patents

Description

The present invention relates to a pneumatic tire.

Conventionally, tires have various required performances, especially for European tires, grip performance under a wide range of conditions such as wet grip performance, on-ice grip performance, dry grip performance tends to be emphasized, and at the same time wear resistance It is important. In order to improve wet grip performance and dry grip performance, methods of blending a large amount of fillers and resins have been studied, but the hardness of the rubber composition and the glass transition temperature Tg are increased, and the grip performance on ice is improved. There is a tendency to decrease.

On the other hand, in order to improve the grip performance on ice, a method of blending a large amount of oil and lowering the rubber hardness at low temperature has been proposed, but the wear resistance is greatly impaired or the wet grip performance cannot be secured sufficiently. Such problems arise. Moreover, although the method of improving dry grip using the styrene butadiene rubber with much styrene amount is also known, Tg raises again and there exists a tendency for grip performance on ice to fall (refer patent document 1).

As described above, it is desired to develop a tire having good wear resistance performance while ensuring grip performance on a road surface in an arbitrary temperature zone and conditions such as a dry road surface, a wet road surface, and a road surface on ice and snow.

JP 2014-9324 A

The present invention solves the above-mentioned problems, and improves the wear resistance while improving the grip performance in a well-balanced manner on the road surface in any temperature zone and conditions such as a dry road surface, a wet road surface, and a road surface on ice and snow. The purpose is to provide.

The present invention is a pneumatic tire having a tread produced by using a rubber composition having a total amount of filler of 70 parts by mass or more with respect to 100 parts by mass of the rubber component, the styrene-butadiene rubber in 100% by mass of the rubber component The content of carbon black is 30 to 70% by mass, the content of carbon black with respect to 100 parts by mass of the rubber component is 40 parts by mass or more, and the rubber physical properties after vulcanization of the rubber composition are hardness at −10 ° C. (Hs ) Is 69 or less, tan δ at 0 ° C. is 0.50 or more when viscoelasticity measurement is performed with initial strain 10%, dynamic strain 2%, tan δ at 30 ° C. is 0.20 to 0.27, glass transition The present invention relates to a pneumatic tire having a temperature (Tg) of −35 ° C. or lower.

［式中、Ｒ^１００１は−Ｃｌ、−Ｂｒ、−ＯＲ^１００６、−Ｏ（Ｏ＝）ＣＲ^１００６、−ＯＮ＝ＣＲ^１００６Ｒ^１００７、−ＯＮ＝ＣＲ^１００６Ｒ^１００７、−ＮＲ^１００６Ｒ^１００７及び−（ＯＳｉＲ^１００６Ｒ^１００７）_ｈ（ＯＳｉＲ^１００６Ｒ^１００７Ｒ^１００８）から選択される一価の基（Ｒ^１００６、Ｒ^１００７及びＲ^１００８は同一でも異なっていても良く、各々水素原子又は炭素数１〜１８の一価の炭化水素基であり、ｈは平均値が１〜４である。）であり、Ｒ^１００２はＲ^１００１、水素原子又は炭素数１〜１８の一価の炭化水素基、Ｒ^１００３はＲ^１００１、Ｒ^１００２、水素原子又は−［Ｏ（Ｒ^１００９Ｏ）_ｊ］_０．５−基（Ｒ^１００９は炭素数１〜１８のアルキレン基、ｊは１〜４の整数である。）、Ｒ^１００４は炭素数１〜１８の二価の炭化水素基、Ｒ^１００５は炭素数１〜１８の一価の炭化水素基を示し、ｘ、ｙ及びｚは、ｘ＋ｙ＋２ｚ＝３、０≦ｘ≦３、０≦ｙ≦２、０≦ｚ≦１の関係を満たす数である。］ The rubber composition preferably contains a liquid resin and / or a liquid polymer.
The rubber composition preferably includes a silane coupling agent represented by the following formula (S1).

[Wherein R ¹⁰⁰¹ represents —Cl, —Br, —OR ¹⁰⁰⁶ , —O (O═) CR ¹⁰⁰⁶ , —ON = CR ¹⁰⁰⁶ R ¹⁰⁰⁷ , —ON = CR ¹⁰⁰⁶ R ¹⁰⁰⁷ , —NR ¹⁰⁰⁶ R ¹⁰⁰⁷ and — ( The monovalent groups (R ¹⁰⁰⁶ , R ^1007, and R ¹⁰⁰⁸ ) selected from OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ ) _h (OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ R ¹⁰⁰⁸ ) may be the same or different and each have a hydrogen atom or a carbon number of 1 to 18 R is a monovalent hydrocarbon group, h has an average value of 1 to 4, and R ¹⁰⁰² is R ¹⁰⁰¹ , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, and R ¹⁰⁰³ is R ^{1001, R 1002,} a hydrogen atom or _{^{- [O (R 1009 O)}} j] 0.5 - group ^{(R 1009} represents an alkylene group having 1 to 18 carbon atoms, j is 1 to 4 Is an ^{integer.), R 1004} represents a divalent hydrocarbon ^{group, R 1005} is a monovalent hydrocarbon group having 1 to 18 carbon atoms having 1 to 18 carbon atoms, x, y and z, x + y + 2z = 3 , 0 ≦ x ≦ 3, 0 ≦ y ≦ 2, and 0 ≦ z ≦ 1. ]

The rubber composition preferably contains silica and aluminum hydroxide.
The carbon black preferably has a nitrogen adsorption specific surface area of 120 m ² / g or more and an average primary particle diameter of 20 nm or less.
The volume solid resistance value after vulcanization of the rubber composition is preferably less than 1 × 10 ⁸ Ω · cm.

According to the present invention, the rubber composition having a tread produced using a rubber composition having a predetermined total amount of filler, a styrene butadiene rubber amount and a carbon black amount, and a rubber physical property after vulcanization of the rubber composition, Since it is a pneumatic tire having a hardness (Hs) at −10 ° C., tan δ at 0 ° C. and 30 ° C., and a glass transition temperature (Tg), any temperature zone and conditions such as a dry road surface, a wet road surface, and a road surface on ice and snow It is possible to improve the wear resistance while improving the grip performance on the road surface in a well-balanced manner.

The pneumatic tire of the present invention has a tread produced using a rubber composition having a predetermined total amount of filler, styrene butadiene rubber amount, and carbon black amount, and the rubber physical properties after vulcanization of the rubber composition , Predetermined hardness at −10 ° C. (Hs), tan δ at 0 ° C. and 30 ° C., and glass transition temperature (Tg).

Thus, by applying a rubber composition containing a predetermined amount of filler, styrene butadiene rubber (SBR) and carbon black and having a predetermined Hg, tan δ, and Tg in a state after vulcanization to a tread, It is possible to provide a pneumatic tire having improved wear resistance while improving grip performance on a road surface in an arbitrary temperature range and conditions such as a wet road surface and a snowy road surface.

Hereinafter, first, the rubber composition used for the tread will be described.
In the rubber composition according to the present invention, the hardness of the rubber composition after vulcanization at 69 ° C. is 69 or less. Thereby, the grip performance on ice and snow can be sufficiently exhibited. The hardness is preferably 68 or less, and more preferably 65 or less. On the other hand, the hardness is preferably 48 or more, and more preferably 50 or more. If it is less than 48, it is soft, the block rigidity of the tire is impaired, and the grip performance on ice may be lowered.

The vulcanized rubber composition has a tan δ at 0 ° C. of 0.50 or more when viscoelasticity measurement is performed with an initial strain of 10% and a dynamic strain of 2%. Thereby, wet grip performance can fully be exhibited. The tan δ is preferably 0.53 or more, and more preferably 0.55 or more. There is no particular upper limit.

The rubber composition after vulcanization has a tan δ at 30 ° C. of 0.20 or more of the rubber composition after vulcanization. Thereby, the dry grip performance is sufficiently exhibited. The tan δ is preferably 0.24 or more. On the other hand, the tan δ is 0.27 or less, and in this case, low fuel consumption can be ensured. There are various indexes of dry grip performance and low fuel consumption performance, but it has been found that the balance with other physical properties can be well determined by defining tan δ at 30 ° C.

The rubber composition after vulcanization has a Tg of −35 ° C. or lower. Thereby, the grip performance on snow and the wear resistance performance are sufficiently exhibited. The Tg is preferably −38 ° C. or lower, and more preferably −40 ° C. or lower.

In the rubber composition after vulcanization, tan δ and Tg at 0 ° C. and 30 ° C. when the viscoelasticity measurement was performed at the above-mentioned hardness at −10 ° C., initial strain 10%, dynamic strain 2% are the amount of filler , SBR amount and carbon black amount are adjusted to predetermined amounts, liquid resin and liquid polymer are blended, silane coupling agent is represented by formula (S1), and both silica and aluminum hydroxide are blended. , By adding a carbon black having a nitrogen adsorption specific surface area of 120 m ² / g or more and an average primary particle diameter of 20 nm or less, a carbon black coupling agent described later, and a crosslinking agent represented by formula (II) described later. It becomes possible to do.

In addition, tan δ and Tg at 0 ° C. and 30 ° C. when viscoelasticity measurement was performed at −10 ° C. hardness, initial strain 10%, and dynamic strain 2% of the rubber composition after vulcanization are described in the examples below. It can be measured by the method described.

In the rubber composition of the present invention, the total amount of the filler is 70 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 70 parts by mass, the wear resistance is inferior or the dry grip property is impaired. The total amount of the filler is more preferably 75 parts by mass or more, further preferably 80 parts by mass or more, and most preferably 85 parts by mass or more. The upper limit of the total amount is preferably 180 parts by mass or less, more preferably 150 parts by mass or less, and most preferably 120 parts by mass or less. If it exceeds 180 parts by mass, the fuel efficiency may be inferior.

As the filler, those known in the tire field can be used, for example, carbon black, mica such as silica, aluminum hydroxide, calcium carbonate, sericite, magnesium oxide, magnesium hydroxide, clay, talc, alumina, Examples include titanium oxide.

By blending carbon black, a good reinforcing effect can be obtained and the effect of preventing electrification can be enhanced. Examples of carbon black that can be used include GPF, FEF, HAF, ISAF, and SAF, but are not particularly limited. Carbon black may be used alone or in combination of two or more. In addition, when assuming that future petroleum resources will be depleted, carbon black using renewable raw materials can be preferably used.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 10 to 3000 m ² / g. The lower limit is preferably 50 m ² / g or more, more preferably 100 m ² / g or more, and still more preferably 120 m ² / g or more. If it is less than 10 m < ² > / g, sufficient weather resistance performance will not be acquired and there exists a tendency for abrasion resistance to fall. On the other hand, when it exceeds 3000 m ² / g, the dispersibility is inferior and the wear resistance tends to decrease. In addition, the nitrogen adsorption specific surface area of carbon black is calculated | required by A method of JISK6217.

In particular, it is preferable that the nitrogen adsorption specific surface area of carbon black is 120 m ² / g or more and the average primary particle diameter is 20 nm or less. In this case, the predetermined hardness at −10 ° C., tan δ and Tg at 0 ° C. and 30 ° C. can be imparted to the rubber composition after vulcanization.

In this case, the nitrogen adsorption specific surface area of carbon black is more preferably not less than 130m ² / g, more preferably more than 140 m ² / g. The average primary particle diameter is more preferably 19 nm from the viewpoint that a good balance between grip performance and wear resistance can be realized. The lower limit of the average primary particle size is not particularly defined, but is preferably 10 nm or more from the viewpoint of workability. In this specification, the average primary particle diameter of carbon black can be determined by observing with a transmission electron microscope, measuring 400 or more primary particles observed in the visual field, and calculating the average.

Carbon black having a large structure (DBP oil supply amount) such as acetylene black or conductive carbon black may be blended. As a result, both excellent charging properties and low fuel consumption can be achieved. Examples of such carbon black include Printex XE2B manufactured by Evonik, # 3030, # 3050, # 3230 manufactured by Mitsubishi Chemical Corporation, VP, VXC305, VXC500, VXC500 manufactured by Cabot, and the like. Not as long.

The content of carbon black is 40 parts by mass or more with respect to 100 parts by mass of the rubber component. Within this range, the mechanical strength of the rubber can be ensured and good electric resistance can be obtained. Moreover, the hardness at the predetermined −10 ° C., tan δ and Tg at 0 ° C. and 30 ° C. can be imparted, and the wear resistance can be improved while improving the grip performance on the road surface in an arbitrary temperature range and condition in a well-balanced manner. The upper limit is preferably 150 parts by mass or less, and more preferably 100 parts by mass or less.

（式中、Ａは、Ｏ、Ｓ、ＮＨ又はＮＲを表す。Ｒは、炭素数１〜６の直鎖状又は分岐状のアルキル基を表す。ｎは１〜１２の整数を表す。） A carbon black coupling agent may be blended in the rubber composition in the present invention.
Although it does not specifically limit as a carbon black coupling agent, For example, the compound shown by following formula (I) can be used conveniently. As a result, the above-mentioned hardness at −10 ° C., tan δ and Tg at 0 ° C. and 30 ° C. can be imparted, and the wear performance can be improved while improving the grip performance on the road surface in any temperature zone and conditions in a well-balanced manner. .

(In the formula, A represents O, S, NH or NR. R represents a linear or branched alkyl group having 1 to 6 carbon atoms. N represents an integer of 1 to 12.)

Examples of the compound represented by the formula (I) include bis (benzimidazolyl-2) methane, 1,2-bis (benzimidazolyl-2) ethane, and 1,2-bis (4-ethylbenzimidazolyl-2). Ethane, 1,2-bis (4-isopropylbenzimidazolyl-2) ethane, 1,2-bis (4-tert-butylbenzimidazolyl-2) ethane, 1,3-bis (benzimidazolyl-2) propane, 1 , 3-bis (1-methylbenzimidazolyl-2) propane, 1,3-bis (1-ethylbenzimidazolyl-2) propane, 1,3-bis (4,5-dimethylbenzimidazolyl-2) propane, Bis (benzimidazolyl-2) alkane such as 1,4-bis (benzimidazolyl-2) butane, bis (substituted benzimidazolyl-2) al Can be mentioned.

Examples of the carbon black coupling agent include bis (benzimidazolyl-2) methyl sulfide, 2,2′-bis (benzimidazolyl-2) ethyl sulfide, 2,2′-bis (benzimidazolyl-2) ethyl disulfide, and the like. Bis (benzimidazolyl-2) alkyl (poly) sulfide, bis (substituted benzimidazolyl-2) alkyl (poly) sulfide; 1,2-bis (mercaptobenzimidazolyl-2) ethane, 1,2-bis (mercapto-) Bis (mercaptobenzimidazolyl-2) alkanes such as 4-methylbenzimidazolyl-2) ethane, 1,3-bis (mercaptobenzimidazolyl-2) propane, 1,4-bis (mercaptobenzimidazolyl-2) butane, bis (Substituted mercaptobenzimidazolyl-2 Alkane; α, α′-bis (mercaptobenzimidazolyl-2) metaxylene, 1,4′-bis (mercaptobenzimidazolyl-2) 2-trans-butene; Also mentioned. Furthermore, halogenated organic acids such as 4-bromocrotonic acid and 4- (bromomethyl) phenylacetic acid; silane compounds are also included.

In the rubber composition of the present invention, the content of the carbon black coupling agent is preferably 3 to 25 parts by mass, more preferably 7 to 18 parts by mass with respect to 100 parts by mass of carbon black. Within the above range, the effects of the present invention can be obtained satisfactorily.

In the present invention, it is preferable to use silica and aluminum hydroxide in combination. As a result, the above-mentioned hardness at −10 ° C., tan δ and Tg at 0 ° C. and 30 ° C. can be imparted, and the wear performance can be improved while improving the grip performance on the road surface in any temperature zone and conditions in a well-balanced manner. .

The silica is not particularly limited, and examples thereof include dry process silica (anhydrous silicic acid), wet process silica (hydrous silicic acid), and the like, but wet process silica is preferable because of its large number of silanol groups.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 40 m ² / g or more, more preferably 50 m ² / g or more, and still more preferably 80 m ² / g or more. Further, the nitrogen adsorption specific surface area _(N 2 SA) is preferably from 300 meters ² / g or less, more preferably 200 meters ² / g, more preferably not more than 130m ² / g. Within the above range, wet grip and on-ice grip performance improvement and other physical properties are well balanced. The _N 2 SA of silica is a value measured by the BET method in accordance with ASTM D3037-81.

The content of silica is preferably 5 parts by mass or more and more preferably 15 parts by mass or more with respect to 100 parts by mass of the rubber component. Moreover, this content becomes like this. Preferably it is 50 mass parts or less, More preferably, it is 30 mass parts or less. Within the above range, the predetermined hardness at −10 ° C., tan δ and Tg at 0 ° C. and 30 ° C. can be imparted.

The average particle diameter of aluminum hydroxide is preferably 10 μm or less, more preferably 5 μm or less, and still more preferably 3 μm or less. If the thickness exceeds 10 μm, good wet grip performance may not be obtained. The average particle diameter is preferably 0.05 μm or more, more preferably 0.1 μm or more. When it is less than 0.05 μm, dispersion becomes difficult and wet grip performance may be deteriorated.

In addition, the average particle diameter of aluminum hydroxide is measured using a transmission type or a scanning electron microscope. The average particle diameter means a major axis, and the major axis is the longest length when the aluminum hydroxide powder is projected onto the projection plane while variously changing the direction of the aluminum hydroxide powder relative to the projection plane.

The content of aluminum hydroxide is preferably 2 parts by mass or more, more preferably 5 parts by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less. Within the above range, the predetermined hardness at −10 ° C., tan δ and Tg at 0 ° C. and 30 ° C. can be imparted.

The compounding ratio of silica and aluminum hydroxide (silica content (parts by mass) / aluminum hydroxide content (parts by mass)) is preferably 50/50 to 90/10, more preferably 60/40 to 80/20. Within the above range, the predetermined hardness at −10 ° C., tan δ and Tg at 0 ° C. and 30 ° C. can be imparted.

When silica is blended, it is preferable to add a silane coupling agent. As the silane coupling agent, any silane coupling agent conventionally used in combination with silica can be used in the rubber industry, and examples thereof include sulfide systems such as bis (3-triethoxysilylpropyl) disulfide, 3- Mercapto type such as mercaptopropyltrimethoxysilane, vinyl type such as vinyltriethoxysilane, amino type such as 3-aminopropyltriethoxysilane, glycidoxy type of γ-glycidoxypropyltriethoxysilane, 3-nitropropyltrimethoxy Examples thereof include nitro compounds such as silane and chloro compounds such as 3-chloropropyltrimethoxysilane.

［式中、Ｒ^１００１は−Ｃｌ、−Ｂｒ、−ＯＲ^１００６、−Ｏ（Ｏ＝）ＣＲ^１００６、−ＯＮ＝ＣＲ^１００６Ｒ^１００７、−ＯＮ＝ＣＲ^１００６Ｒ^１００７、−ＮＲ^１００６Ｒ^１００７及び−（ＯＳｉＲ^１００６Ｒ^１００７）_ｈ（ＯＳｉＲ^１００６Ｒ^１００７Ｒ^１００８）から選択される一価の基（Ｒ^１００６、Ｒ^１００７及びＲ^１００８は同一でも異なっていても良く、各々水素原子又は炭素数１〜１８の一価の炭化水素基であり、ｈは平均値が１〜４である。）であり、Ｒ^１００２はＲ^１００１、水素原子又は炭素数１〜１８の一価の炭化水素基、Ｒ^１００３はＲ^１００１、Ｒ^１００２、水素原子又は−［Ｏ（Ｒ^１００９Ｏ）_ｊ］_０．５−基（Ｒ^１００９は炭素数１〜１８のアルキレン基、ｊは１〜４の整数である。）、Ｒ^１００４は炭素数１〜１８の二価の炭化水素基、Ｒ^１００５は炭素数１〜１８の一価の炭化水素基を示し、ｘ、ｙ及びｚは、ｘ＋ｙ＋２ｚ＝３、０≦ｘ≦３、０≦ｙ≦２、０≦ｚ≦１の関係を満たす数である。］ Especially, it is preferable to use the silane coupling agent represented by a following formula (S1). Thereby, the above-mentioned hardness at −10 ° C., tan δ and Tg at 0 ° C. and 30 ° C. can be imparted.

[Wherein R ¹⁰⁰¹ represents —Cl, —Br, —OR ¹⁰⁰⁶ , —O (O═) CR ¹⁰⁰⁶ , —ON = CR ¹⁰⁰⁶ R ¹⁰⁰⁷ , —ON = CR ¹⁰⁰⁶ R ¹⁰⁰⁷ , —NR ¹⁰⁰⁶ R ¹⁰⁰⁷ and — ( The monovalent groups (R ¹⁰⁰⁶ , R ^1007, and R ¹⁰⁰⁸ ) selected from OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ ) _h (OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ R ¹⁰⁰⁸ ) may be the same or different and each have a hydrogen atom or a carbon number of 1 to 18 R is a monovalent hydrocarbon group, h has an average value of 1 to 4, and R ¹⁰⁰² is R ¹⁰⁰¹ , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, and R ¹⁰⁰³ is R ^{1001, R 1002,} a hydrogen atom or _{^{- [O (R 1009 O)}} j] 0.5 - group ^{(R 1009} represents an alkylene group having 1 to 18 carbon atoms, j is 1 to 4 Is an ^{integer.), R 1004} represents a divalent hydrocarbon ^{group, R 1005} is a monovalent hydrocarbon group having 1 to 18 carbon atoms having 1 to 18 carbon atoms, x, y and z, x + y + 2z = 3 , 0 ≦ x ≦ 3, 0 ≦ y ≦ 2, and 0 ≦ z ≦ 1. ]

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

Specific examples of R ¹⁰⁰² , R ¹⁰⁰⁵ , R ¹⁰⁰⁶ , R ¹⁰⁰⁷ and R ^{1008 in} the above formula (S1) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec- Butyl group, tert-butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, cyclopentyl group, cyclohexyl group, vinyl group, propenyl group, allyl group, hexenyl group, octenyl group, cyclopentenyl group, Examples include cyclohexenyl group, phenyl group, tolyl group, xylyl group, naphthyl group, benzyl group, phenethyl group, naphthylmethyl group and the like.
As examples of R ¹⁰⁰⁹ in the above formula (S1), examples of the linear alkylene group include a methylene group, an ethylene group, an n-propylene group, an n-butylene group, a hexylene group, and the like. , Isopropylene group, isobutylene group, 2-methylpropylene group and the like.

Specific examples of the silane coupling agent represented by the above formula (S1) include 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltriethoxysilane, 3 -Lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane, 3-hexa Noylthiopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2 Octanoylthiopropyl ethyltrimethoxysilane, 2- deca Neu thio ethyltrimethoxysilane, and 2-lauroyl thio ethyl trimethoxysilane. Of these, 3-octanoylthiopropyltriethoxysilane (NXT silane manufactured by Momentive Performance Materials) is particularly preferable in terms of both workability and low fuel consumption. The silane coupling agent may be used alone or in combination of two or more.

In the rubber composition of the present invention, the content of the silane coupling agent is preferably 1 to 10 parts by mass and more preferably 3 to 8 parts by mass with respect to 100 parts by mass of silica. Within the above range, the effects of the present invention can be obtained satisfactorily.

In the rubber composition of the present invention, the content of styrene butadiene rubber (SBR) in 100% by mass of the rubber component is 30 to 70% by mass. As a result, the above-mentioned hardness at −10 ° C., tan δ and Tg at 0 ° C. and 30 ° C. can be imparted, and the wear performance can be improved while improving the grip performance on the road surface in any temperature zone and conditions in a well-balanced manner. .

The SBR is not particularly limited, and examples thereof include emulsion polymerization SBR (E-SBR), solution polymerization SBR (S-SBR), and modified SBR for silica modified with a compound having an interaction with silica.

SBR has a bound styrene content of 15% by mass or more, preferably 20% by mass or more. The amount of the bound styrene is 50% by mass or less, preferably 35% by mass or less, more preferably 25% by mass or less. If it is less than 15% by mass, the wet grip performance is insufficient and the effect of the present invention may not be sufficiently obtained. If it exceeds 50% by mass, it may be difficult to disperse the polymer.

Other rubber components that can be used in addition to SBR include natural rubber (NR), epoxidized natural rubber (ENR), isoprene rubber (IR), butadiene rubber (BR), styrene isoprene butadiene rubber (SIBR), and ethylene propylene diene rubber. (EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR) and the like. These modified rubbers may be used.

As another rubber component, a modified natural rubber that is highly purified and has a pH adjusted to 2 to 7 can be suitably used. Due to excellent processability, the filler is highly dispersed, realizing low fuel consumption and isotropic properties. Examples of the modified natural rubber include those disclosed in International Publication No. WO2014 / 125700.

High purification means removing impurities such as phospholipids and proteins other than the natural polyisoprenoid component, and the phosphorus content in the modified natural rubber is preferably 200 ppm or less, more preferably 150 ppm or less. The phosphorus content can be measured by a conventional method such as ICP emission analysis. The modified natural rubber preferably has a nitrogen content of 0.15% by mass or less, preferably 0.1% by mass or less after being immersed in acetone at room temperature (25 ° C.) for 48 hours. More preferred. The nitrogen content is a measured value after the artificial anti-aging agent in the rubber is removed by extraction with acetone, and can be measured by a conventional method such as Kjeldahl method or trace nitrogen meter. A method for highly purifying the highly purified NR is not particularly limited, and examples thereof include mechanical methods such as centrifugation, impurity decomposition methods such as proteins using enzymes, and impurity separation by saponification.

The pH of the modified natural rubber is cut into a size of 2 mm square or less on each side, immersed in distilled water, extracted at 90 ° C. for 30 minutes while being irradiated with microwaves, and the immersion water is measured using a pH meter. Specifically, it is measured by the method described in the examples described later.

In the rubber composition of the present invention, the content of the modified natural rubber in 100% by mass of the rubber component is preferably 50 to 70% by mass from the viewpoints of low fuel consumption, heat resistance, rubber strength, processability and the like. .

As another rubber component, a high cis polybutadiene rubber having a cis content of 95% by mass or more is also suitable. As a result, excellent on-ice grip performance and wear resistance can be obtained. The cis content is preferably 98% by mass or more.

The Mooney viscosity ML _{1 + 4} (100 ° C.) of the high-cis polybutadiene rubber is preferably 50 or more, more preferably 60 or more, and still more preferably 65 or more. The Mooney viscosity is preferably 150 or less, more preferably 120 or less.
The Mooney viscosity is measured according to JIS K 6300: 2001-1.

The high cis polybutadiene rubber is preferably a rare earth BR. As the rare earth element-based catalyst used for the synthesis of the rare earth-based BR, a known one can be used, for example, a catalyst using a lanthanum series rare earth element compound can be preferably used. Further, if necessary, a lanthanum series rare earth element compound can be used in combination with an organoaluminum compound, an aluminoxane, a halogen-containing compound, and a Lewis base. Among these, an Nd-based catalyst using a neodymium (Nd) -containing compound as a lanthanum series rare earth element compound is particularly preferable.

The high cis polybutadiene rubber is preferably linear, and the Mw / Mn of the high cis high molecular weight BR is preferably 1 to 3, more preferably 1 to 2.8, and more preferably 1 to 2.6. Further preferred.

In the rubber composition of the present invention, the content of the high cis polybutadiene rubber in 100% by mass of the rubber component is preferably 10 to 30% by mass.

The rubber composition in the present invention preferably contains a crosslinking agent such as an organic crosslinking agent or an organic-inorganic hybrid crosslinking agent. Thereby, excellent isotropy of rubber strength and physical properties can be obtained. The organic crosslinking agent and the organic / inorganic hybrid crosslinking agent are not particularly limited, but are thermosetting resins such as resorcinol resins, cresol resins, phenol resins, melamine resins, maleimide compounds, alkylphenol / sulfur chloride condensates. , Organic peroxides, amine organic sulfides and the like. The crosslinking agents may be used alone or in combination of two or more, and may be used in combination with sulfur.

（式中、Ｅは炭素数２〜１０のアルキレン基、Ｒ^１０１及びＲ^１０２は、同一若しくは異なって、窒素原子を含む１価の有機基を表す。） Especially, it is preferable to use the compound represented by following formula (II) as a crosslinking agent. Thereby, a CC bond with high binding energy and high thermal stability can be retained in the rubber composition. As a result, the above-mentioned hardness at −10 ° C., tan δ and Tg at 0 ° C. and 30 ° C. can be imparted, and the wear performance can be improved while improving the grip performance on the road surface in any temperature zone and conditions in a well-balanced manner. .

(In the formula, E represents an alkylene group having 2 to 10 carbon atoms, and R ¹⁰¹ and R ¹⁰² are the same or different and each represents a monovalent organic group containing a nitrogen atom.)

The alkylene group for E is not particularly limited, and includes linear, branched, and cyclic groups. Among them, a linear alkylene group is preferable.

Carbon number of the alkylene group of E is 2-10, Preferably it is 4-8. When the number of carbon atoms in the alkylene group is 1, the thermal stability tends to be poor, and the effect of having an alkylene group tends to be insufficient. When the number of carbon atoms is 11 or more, -S-S-E-S- There is a tendency that formation of a crosslinked chain represented by S- becomes difficult.

Examples of the alkylene group satisfying the above conditions include ethylene group, trimethylene group, tetramethylene group, pentamethylene group, hexamethylene group, heptamethylene group, octamethylene group, decamethylene group and the like. Among these, a hexamethylene group is preferred because a cross-link represented by -S-S-E-SS-S is smoothly formed between the polymers and is thermally stable.

R ¹⁰¹ and R ¹⁰² are not particularly limited as long as they are monovalent organic groups containing a nitrogen atom, but those containing at least one aromatic ring are preferred, and N—C (═S) in which a carbon atom is bonded to a dithio group. )-Is more preferable. R ¹⁰¹ and R ¹⁰² may be the same or different from each other, but are preferably the same for reasons such as ease of production.

Examples of the compound represented by the formula (II) include 1,2-bis (N, N′-dibenzylthiocarbamoyldithio) ethane and 1,3-bis (N, N′-dibenzylthiocarbamoyldithio). Propane, 1,4-bis (N, N′-dibenzylthiocarbamoyldithio) butane, 1,5-bis (N, N′-dibenzylthiocarbamoyldithio) pentane, 1,6-bis (N, N ′) -Dibenzylthiocarbamoyldithio) hexane, 1,7-bis (N, N'-dibenzylthiocarbamoyldithio) heptane, 1,8-bis (N, N'-dibenzylthiocarbamoyldithio) octane, 1,9 -Bis (N, N′-dibenzylthiocarbamoyldithio) nonane, 1,10-bis (N, N′-dibenzylthiocarbamoyldithio) decane and the like. Among these, 1,6-bis (N, N′-dibenzylthiocarbamoyldithio) hexane is preferable because it is thermally stable and has excellent polarizability.

In the rubber composition of the present invention, the content of the compound represented by the formula (II) is preferably 0.5 to 6 parts by mass, more preferably 1 to 4 parts by mass with respect to 100 parts by mass of the rubber component. It is.

The rubber composition in the present invention preferably contains zinc oxide. As a result, vulcanization becomes smooth and rigidity and physical properties are obtained. Zinc oxide is not particularly limited, and zinc oxide conventionally used in the rubber industry (eg, silver candy R manufactured by Toho Zinc Co., Ltd., zinc oxide manufactured by Mitsui Metal Mining Co., Ltd.) or an average particle size of 200 nm or less. Fine particle zinc oxide (such as Zinccock Super F-2 manufactured by Hakusuitec Co., Ltd.).

The compounding amount of zinc oxide is preferably 1.0 part by mass or more, more preferably 1.5 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 1.0 part by mass, sufficient hardness (Hs) may not be obtained due to vulcanization reversion. The blending amount is preferably 3.7 parts by mass or less, more preferably 3.0 parts by mass or less. If it exceeds 3.7 parts by mass, the breaking strength tends to decrease.

The rubber composition in the present invention preferably contains a plasticizer such as oil, liquid polymer, or liquid resin from the viewpoint of processability. The type of plasticizer is not particularly limited, but from the viewpoint of the environment, a plasticizer that does not contain 3% or more of polycyclic aromatic (PCA) is preferable.

Of these, the use of a liquid polymer or a liquid resin can impart the above-mentioned hardness at −10 ° C., tan δ and Tg at 0 ° C. and 30 ° C. It is also preferable from the viewpoint of both wear resistance and grip performance, and the wear performance can be improved while improving the grip performance on a road surface in an arbitrary temperature range and condition in a well-balanced manner.

The liquid polymer is a polymer (diene polymer) in a liquid state at room temperature (25 ° C.). For example, a liquid styrene butadiene copolymer (liquid SBR), a liquid butadiene polymer (liquid BR), a liquid isoprene polymer ( Liquid diene polymers such as liquid IR) and liquid styrene isoprene copolymer (liquid SIR). The liquid polymer is not included in the rubber component.

The number average molecular weight (Mn) of the liquid polybutadiene is preferably 600 or more, more preferably 5000 or more. If it is less than 600, the effect of improving the wear resistance tends to be small. The number average molecular weight is preferably 20000 or less, more preferably 15000 or less. When it exceeds 20000, the function as a softening agent tends to be hardly exhibited.
In the present specification, the number average molecular weight is determined by gel permeation chromatograph (GPC) (GPC-8000 series, manufactured by Tosoh Corporation), detector: differential refractometer, column: TSKGEL SUPERMALTPORE HZ- manufactured by Tosoh Corporation. It is determined by standard polystyrene conversion based on the measured value by M).

In the rubber composition of the present invention, the content of the liquid polymer (liquid diene polymer) is preferably 2 to 30 parts by mass, more preferably 5 to 20 parts by mass with respect to 100 parts by mass of the rubber component.

The liquid resin is not particularly limited as long as it is not cured at room temperature (25 ° C.), but liquid coumarone indene resin, liquid terpene resin and the like can be suitably used. Among these, liquid coumarone indene resin is preferable.

The liquid coumarone indene resin is a resin containing coumarone and indene as monomer components constituting the resin skeleton (main chain). In addition to coumarone and indene, monomer components contained in the skeleton include styrene and α-methylstyrene. , Methylindene, vinyltoluene and the like.

The softening point of the liquid coumarone indene resin is preferably -20 to 45 ° C. An upper limit becomes like this. Preferably it is 40 degrees C or less, More preferably, it is 35 degrees C or less. The lower limit is preferably −10 ° C. or higher, more preferably −5 ° C. or higher. In the present specification, the softening point of the coumarone indene resin is a temperature at which the sphere descends when the softening point specified in JIS K 6220-1: 2001 is measured with a ring and ball softening point measuring apparatus.

In the rubber composition in the present invention, the content of the liquid resin is preferably 3 to 40 parts by mass, more preferably 10 to 30 parts by mass with respect to 100 parts by mass of the rubber component.

In addition to the components described above, the rubber composition in the present invention is appropriately blended with materials generally used in the tire industry, such as stearic acid, anti-aging agents, waxes, and vulcanization accelerators. May be.

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

The rubber composition in the present invention has a volume resistivity value after vulcanization of preferably less than 1 × 10 ⁸ Ω · cm, and more preferably less than 1 × 10 ⁷ Ω · cm. Thereby, charging of the tire can be prevented. The volume resistivity value can be measured according to JIS K 6271.

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

The present invention will be specifically described based on examples, but the present invention is not limited to these examples.
The various chemicals used in the examples are described below.
NR1: High purity NR (modified NR) produced in the following production example
NR2: TSR20
SBR: Nipol NS616 (non-oil extended, styrene content: 21%, vinyl content: 63%, Tg: -25 ° C, weight average molecular weight: 800,000) manufactured by Zeon Corporation
BR1: Buna CB21 manufactured by LANXESS (high-cis BR, BR synthesized using an Nd-based catalyst, cis content: 98% by mass, ML _{1 + 4} (100 ° C.): 73, Mw / Mn: 2.4)
BR2: UBEPOL BR150B manufactured by Ube Industries, Ltd. (cis content: 97% by mass, ML _{1 + 4} (100 ° C.): 40, Mw / Mn: 3.3)
CB1: N134 manufactured by Tokai Carbon Co., Ltd. (N ₂ SA: 143 m ² / g, average primary particle size: 19 nm)
CB2: Seast N220 manufactured by Mitsubishi Chemical Corporation (N ₂ SA: 114 m ² / g, average primary particle size: 22 nm)
Aluminum hydroxide: Heidilite H-43 (average particle size: 0.6 μm) manufactured by Showa Denko
Silica: ZEOSIL 115GR manufactured by Rhodia (N ₂ SA: 115 m ² / g)
Coupling agent 1: 1,2-bis (benzimidazolyl-2) ethane coupling agent 2 manufactured by Shikoku Kasei Co., Ltd. 2: NXT (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive
Coupling agent 3: Si69 manufactured by Evonik Degussa
Plasticizer 1: NOVARES C10 manufactured by Rutgers Chemicals (liquid coumarone indene resin, softening point: 5 to 15 ° C.)
Plasticizer 2: Kuraray LBR-307 (liquid polybutadiene, number average molecular weight 8000)
Plasticizer 3: Diana Process Oil AH-24 manufactured by Idemitsu Kosan Co., Ltd.
Wax 1: Kester Wax K82P manufactured by Koster Keunen
Wax 2: Ozoace 0355 manufactured by Nippon Seiwa Co., Ltd.
Stearic acid: Zinc oxide manufactured by NOF Corporation: Zinc oxide 3-type cross-linking agent manufactured by HAXITEC Co., Ltd. 1: Vulcuren KA9188 (1,6-bis (N, N'-dibenzylthiocarbamoyldithio) hexane manufactured by LANXESS )
Sulfur: Powder sulfur vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd. 1: Noxeller NS (Nt-butyl-2-benzothiazylsulfenamide) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Vulcanization accelerator 2: Noxeller D (N, N'-diphenylguanidine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Anti-aging agent: NOCRACK 6C manufactured by Ouchi Shinsei Chemical Co., Ltd.

(Production example of highly purified NR)
After adjusting the solid content concentration (DRC) of the field latex to 30% (w / v), 25 g of 10% Emar E-27C aqueous solution and 60 g of 25% NaOH aqueous solution were added to 1000 g of the latex and saponified for 24 hours at room temperature. Reaction was performed to obtain a saponified natural rubber latex. Next, 6 g of the anti-aging dispersion was added and stirred for 2 hours, and then further diluted with water to a rubber concentration of 15% (w / v). Next, formic acid was added with slow stirring to adjust the pH to 4.0, and then a cationic polymer flocculant was added and stirred for 2 minutes for aggregation. The diameter of the aggregate (aggregated rubber) thus obtained was about 0.5 to 5 mm. The obtained agglomerates were taken out and immersed in 1000 ml of a 2% by weight aqueous sodium carbonate solution at room temperature for 4 hours, and then the rubber was taken out. To this, 2000 ml of water was added and stirred for 2 minutes to remove water as much as possible 7 times. Thereafter, 500 ml of water was added, 2% by mass formic acid was added until pH 4 was reached, and the mixture was allowed to stand for 15 minutes. Further, after removing the water as much as possible, repeating the operation of adding water again and stirring for 2 minutes three times, squeezing the water with a water squeezing roll to form a sheet, and then drying at 90 ° C. for 4 hours to obtain a solid rubber Obtained.
The obtained rubber had a pH of 5.0, a phosphorus content of 92 ppm, and a nitrogen content of 0.07% by mass. Each physical property was evaluated as follows.

<Measurement of pH of rubber>
5 g of the obtained rubber was cut to 5 mm or less (about 1-2 × about 1-2 × about 1-2 (mm)) and placed in a 100 ml beaker, and 50 ml of distilled water at room temperature was added to 90 ° C. for 2 minutes. The temperature was raised, and then irradiation with microwaves (300 W) was performed for 13 minutes (15 minutes in total) while adjusting the temperature to be maintained at 90 ° C. Next, the immersion water was cooled with an ice bath to 25 ° C., and then the pH of the immersion water was measured using a pH meter.

<Measurement of phosphorus content>
The phosphorus content was determined using an ICP emission spectrometer (P-4010, manufactured by Hitachi, Ltd.).

<Measurement of nitrogen content>
(Acetone extraction (test piece preparation))
About 0.5 g of a sample obtained by chopping each solid rubber into 1 mm square was prepared. The sample was immersed in 50 g of acetone, and after 48 hours at room temperature (25 ° C.), the rubber was taken out and dried to obtain each test piece (extracted with anti-aging agent).
(Measurement)
The nitrogen content of the obtained test piece was measured by the following method.
The nitrogen content was determined by decomposing and gasifying each of the acetone-extracted test pieces obtained above using a trace nitrogen carbon measuring device “SUMIGRAPH NC95A (manufactured by Sumika Chemical Analysis Center)”. The nitrogen content was quantified by analyzing with a gas chromatograph “GC-8A (manufactured by Shimadzu Corporation)”.

[Manufacture of vulcanized rubber composition and test tire]
According to the contents shown in Table 1, materials other than sulfur and a vulcanization accelerator were kneaded for 3 minutes under a condition of 150 ° C. using a 1.7 L Banbury mixer to obtain a kneaded product. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and kneaded for 5 minutes at 80 ° C. using a biaxial open roll to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was vulcanized at 150 ° C. for 30 minutes to obtain a vulcanized rubber composition.

The obtained unvulcanized rubber composition was rolled into a sheet of about 2 mm thickness, processed into a tread shape, bonded to another tire member, molded into a tire, and vulcanized at 170 ° C. for 10 minutes. Thus, a test tire (tire size: 195 / 65R15) was obtained.

[Evaluation]
The obtained vulcanized rubber composition and test tire were evaluated as follows, and the test results are shown in Table 1.

<Measurement of viscoelasticity>
Each composition (vulcanized rubber composition) using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.) at temperatures of 0 ° C. and 30 ° C., a frequency of 10 Hz, an initial strain of 10% and a dynamic strain of 2%. ) Was measured.

<Hardness>
According to JIS K6253 “Method for testing hardness of vulcanized rubber and thermoplastic rubber”, the hardness at −10 ° C. of each rubber test piece (vulcanized rubber composition) was measured with a type A durometer.

<Glass transition temperature (Tg)>
About each rubber test piece (vulcanized rubber composition) in accordance with JIS-K7121, using a differential scanning calorimeter (Q200) manufactured by T.A. The midpoint glass transition temperature was measured.

<Conductivity test>
Each rubber test piece (vulcanized rubber composition) was applied using a digital ultrahigh resistance microammeter (R-8340A) manufactured by Advantest Corporation under constant temperature and humidity conditions of 23 ° C. and relative humidity of 55%. The specific resistance value (volume resistivity) was measured by setting the voltage to 1000 V and measuring the others in accordance with JIS K6271. When each sample was less than 1 × 10 ⁸ Ω · cm, it was indicated as “◯”, and when it was 1 × 10 ⁸ Ω · cm or more, “Δ”.

<Wet grip performance>
A test tire was mounted on all wheels of a vehicle (domestic FF2000cc), and a braking distance from an initial speed of 100 km / h was determined on a wet asphalt road surface. With the braking distance of the reference comparative example as 100, the wet grip performance index was calculated by the following formula. The larger the number, the better the wet grip performance.
Wet grip performance index = (braking distance of reference comparative example) / (braking distance of each formulation) × 100

<Dry grip performance>
The test tires were mounted on all wheels of a vehicle (domestic FF2000cc), and the vehicle was run on a dry asphalt road test course. The test driver evaluated the stability of control during steering at that time, and an index was displayed with the reference comparative example being 100. The larger the value, the better the grip performance on the dry road surface.

<Low fuel consumption performance>
Under the condition of 25 ° C., the rolling resistance was measured by running the test tire on a drum under the conditions of a load of 4.9 N, an internal pressure of the tire of 2.00 kPa, and a speed of 80 km / hour. The rolling resistance of the reference comparative example was set to 100, and each formulation was indexed. The larger the index, the smaller the rolling resistance and the better the fuel efficiency.

<Grip performance on ice>
The test place was the Hokkaido Asahikawa test course (on ice) of Sumitomo Rubber Industries, Ltd., and the on-ice temperature was -1 to -6 ° C.
The test tires were mounted on all the wheels of a vehicle (domestic FF2000cc), and braking performance (on-ice braking stop distance): the stop distance on ice required to stop the stepping on the lock brake at a speed of 30 km / h was measured. The standard comparative example was set to 100, and the index was expressed by the following formula. The larger the index, the better the grip performance on ice.
(Grip performance index on ice) = (stop distance of reference comparative example) / (stop distance of each formulation) × 100

<Grip performance on snow>
The prototype tire was mounted on a domestic 2000cc FR vehicle, and the braking stop distance from 30 km / h was measured on snow. Using the reference comparative example as a reference, the evaluation was performed using the index determined by the following formula. The larger the index, the better the grip performance on snow.
(Grip performance index on snow) = (Stop distance of reference comparative example) / (Stop distance of each formulation) × 100

<Abrasion resistance>
The test tire was mounted on a domestic 2-D vehicle, and the groove depth of the tire tread portion after a mileage of 50,000 km was measured. The travel distance when the tire groove depth was reduced by 1 mm was calculated and indicated by an index using the following formula. The higher the index, the better the wear resistance.
(Abrasion resistance performance index) = (travel distance of each formulation) / (travel distance of reference comparative example) × 100

<Overall performance>
The overall performance was evaluated using the sum of the wet grip index, dry grip performance index, low fuel consumption performance index (rolling resistance index), ice grip performance index, snow grip performance index, and wear resistance performance index obtained above. The target value is 610 or more, and more preferably 615 or more.

A tread having a SBR content of 30 to 70% by mass, a total amount of filler of 40 parts by mass or more of carbon black being 70 parts by mass or more, and having a predetermined hardness after vulcanization, tan δ and Tg at 0 ° C. and 30 ° C. In the tires of the examples, the grip performance on the dry road surface, the wet road surface, and the road surface on ice and snow was improved in a well-balanced manner, and excellent wear resistance performance was obtained.

In particular, liquid coumarone indene resin, liquid polybutadiene, NXT (formula (S1)), both silica and aluminum hydroxide components, CB1 (N ₂ SA: 143 m ² / g, average primary particle size: 19 nm), 1, 2 In Examples using bis (benzimidazolyl-2) ethane (formula (I)), KA9188 (formula (II)), the desired performance was obtained.

On the other hand, when these components were not used, or when the amount of SBR and carbon black were not predetermined, predetermined physical properties could not be imparted after vulcanization, resulting in poor performance.

Claims (5)

A pneumatic tire having a tread produced using a rubber composition having a total amount of filler of 70 parts by mass or more and 180 parts by mass or less based on 100 parts by mass of a rubber component,
The content of styrene butadiene rubber in 100% by mass of the rubber component is 30 to 70% by mass,
The content of carbon black with respect to 100 parts by mass of the rubber component is 40 parts by mass or more,
The rubber composition includes at least one selected from the group consisting of a liquid resin and a liquid polymer,
The liquid resin is at least one selected from the group consisting of a liquid coumarone indene resin and a liquid terpene resin, the liquid polymer is a liquid diene polymer,
The content of the liquid resin with respect to 100 parts by mass of the rubber component is 3 to 40 parts by mass, the content of the liquid polymer is 2 to 30 parts by mass,
The rubber composition after vulcanization of the rubber composition has a hardness (Hs) at −10 ° C. of 69 or less, an initial strain of 10%, a dynamic strain of 2%, and a tan δ at 0 ° C. of 0% at 0 ° C. A pneumatic tire having a tan δ of 0.20 to 0.27 at 30 ° C. and a glass transition temperature (Tg) of −35 ° C. or lower. The pneumatic tire according to claim 1, wherein the rubber composition includes a silane coupling agent represented by the following formula (S1).

[Wherein R ¹⁰⁰¹ represents —Cl, —Br, —OR ¹⁰⁰⁶ , —O (O═) CR ¹⁰⁰⁶ , —ON = CR ¹⁰⁰⁶ R ¹⁰⁰⁷ , —ON = CR ¹⁰⁰⁶ R ¹⁰⁰⁷ , —NR ¹⁰⁰⁶ R ¹⁰⁰⁷ and — ( The monovalent groups (R ¹⁰⁰⁶ , R ^1007, and R ¹⁰⁰⁸ ) selected from OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ ) _h (OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ R ¹⁰⁰⁸ ) may be the same or different and each have a hydrogen atom or a carbon number of 1 to 18 R is a monovalent hydrocarbon group, h has an average value of 1 to 4, and R ¹⁰⁰² is R ¹⁰⁰¹ , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, and R ¹⁰⁰³ is R ^{1001, R 1002,} a hydrogen atom or _{^{- [O (R 1009 O)}} j] 0.5 - group ^{(R 1009} represents an alkylene group having 1 to 18 carbon atoms, j is 1 to 4 Is an ^{integer.), R 1004} represents a divalent hydrocarbon ^{group, R 1005} is a monovalent hydrocarbon group having 1 to 18 carbon atoms having 1 to 18 carbon atoms, x, y and z, x + y + 2z = 3 , 0 ≦ x ≦ 3, 0 ≦ y ≦ 2, and 0 ≦ z ≦ 1. ] The pneumatic tire according to claim 1 or 2, wherein the rubber composition contains silica and aluminum hydroxide. The pneumatic tire according to claim 1, wherein the carbon black has a nitrogen adsorption specific surface area of 120 m ² / g or more and an average primary particle diameter of 20 nm or less. The pneumatic tire according to claim 1, wherein the rubber composition has a volume solid resistance value after vulcanization of less than 1 × 10 ⁸ Ω · cm.