JPH11334310A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the maneuverability by containing a specific amount of each styrene-butadiene copolymer rubber or more, a specific % or more of total combined styrene, a specific amount of aluminum hydroxide, and a specific amount of a compound such as metallic salt of dithiophosphoric acid having a specific formula, in a specific weight part of rubber component. SOLUTION: This rubber in a tread part contains 50 pts.wt. or more of styrene-butadiene copolymer rubber (SBR) in 100 pts.wt. of rubber component, 20 wt.% or more of total combined styrene in rubber component is blended in this SBR, and this rubber contains 5 to 40 pts.wt. of aluminum hydroxide for 100 pts.wt. of rubber component. Moreover, a dithiophosphoric acid compound is selected from a group of dithiophosphoric acid metallic salt expressed by a formula (wherein, R<1> , R<2> denote alkyl group having the number of carbons of 1 to 8 or aryl group having the number of carbons of 6 to 10 independently, the alkyl group is like straight chain or cyclic group or the like. M<1> denotes Zn atom, Sb atom or the like and (n) denotes the number of valence of metal), and 0.2 to 10.0 pts.wt. of the dithiophosphoric acid compound is contained for 100 pts.wt. of rubber component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire having excellent wet steering stability (hereinafter, simply referred to as "steerability") from an early stage to a middle stage.

[0002]

2. Description of the Related Art In recent years, as automobiles have become higher in horsepower, higher in function and longer in life, there has been a demand for tires having excellent maneuverability from the middle stage of driving. In particular, in passenger car tires, the tire changes from a bias tire to a radial tire,
Even for radial tires, the flattening rate is 82 to 70 and 65
With the change to, highly maneuverability with high altitude is strongly demanded.

As one of the solutions, various rubber compounding agents for tire treads have been studied, but if attention is paid to vulcanization accelerators, JP-A-58-87138 discloses a specific vulcanization accelerator. It is disclosed that a rubber composition containing a specific anti-aging agent improves the heat-resistant curing property and improves the appearance at the end of running of the tire. However, the exercise performance and the like of the tire have not been studied at all. Also, JP-A-56-139542
The publication discloses that a rubber composition using a specific vulcanization accelerator improves sintering (scorchability) in rubber kneading, but there is no description or suggestion regarding the performance of the tire. In addition, if attention is paid to inorganic fillers, Japanese Patent Application Laid-Open
The 53003 publication discloses that a rubber composition using alumina improves the initial maneuverability of the tire, but cannot maintain this maneuverability until after the middle stage of traveling.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a pneumatic tire having excellent tire maneuverability from an early stage to a middle stage. It is in.

[0005]

Means for Solving the Problems The present inventors have focused on the rubber components and various compounding agents to be compounded in the tread rubber, and as a result of intensive studies, have found that the problems can be solved by the following means. Was completed.

That is, (1) In the pneumatic tire of the present invention, the rubber composition in the tread portion contains 50 parts by weight or more of styrene-butadiene copolymer rubber in 100 parts by weight of the rubber component, and 20% by weight of total bound styrene
As described above, based on 100 parts by weight of the rubber component, 5 to 40 parts by weight of aluminum hydroxide is contained, and the following general formula
A rubber component comprising at least one dithiophosphate compound selected from the group consisting of a metal dithiophosphate represented by (I), O, O'-dialkyldithiophosphate disulfide and O, O'-dialkyldithiophosphate tetrasulfide; It is characterized by having a tread portion composed of a rubber composition containing 0.2 to 10.0 parts by weight with respect to 100 parts by weight.

[0007]

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Wherein R ¹ and R ² are each independently
Represents an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 10 carbon atoms. This alkyl group may be linear, branched or cyclic. M ¹ represents a Zn atom, an Sb atom, an Fe atom or a Cu atom, and n represents the number of valences of the metal to be bonded. (2) The metal dithiophosphate represented by the general formula (I) described in the above item (1) is preferably a dithiophosphate-based compound represented by the following general formula (II).

[0009]

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(Wherein, M ² represents a Zn atom or an Sb atom, and n represents the number of valences of the metal to be bonded.) (3) In the pneumatic tire of the present invention, the rubber composition of the tread portion is Styrene-butadiene copolymer rubber in 50 parts by weight or more in 100 parts by weight of the rubber component, the total bound styrene content in the rubber component is 20% by weight or more, and the rubber component 1
5 parts by weight to 40 parts by weight of aluminum hydroxide, and the following general formulas (III), (IV), (V) and (V)
At least one benzothiazole compound selected from the group consisting of the compounds represented by I)
It is characterized by having a tread portion composed of a rubber composition containing 0.2 to 10.0 parts by weight with respect to parts by weight.

[0011]

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[0012]

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[0013]

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[0014]

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(Wherein R ³ and R ⁴ are each independently
Hydrogen atom, alkyl group having 1 to 8 carbon atoms or 6 to 1 carbon atoms
Represents an aryl group of 0. However, the case where R ³ and R ⁴ are a hydrogen atom at the same time is excluded. R ⁵ represents an alkyl group, an alkenyl group or a cycloalkyl group having 1 to 8 carbon atoms, R ⁶
Represents a hydrogen atom or -N amino group represented by (R ⁷⁾ R ^8, an alkyl group or a cyclohexyl group of R ⁷ and R ⁸ are each independently a hydrogen atom or a C2-4. However, the case where R ⁷ and R ⁸ are a hydrogen atom at the same time is excluded.
R ⁹ and R ¹⁰ each independently represent an alkyl group, alkenyl group or cycloalkyl group having 1 to 8 carbon atoms. X is Z
represents n atom, an amino group represented by Cu atom or> N-R ^13, R ¹³ represents an alkyl group or a cyclohexyl group having 2 to 4 carbon atoms. R ¹¹ and R ¹² have the same meaning as R ⁹ . (4) R ³ and R ⁴ of the benzothiazole compound represented by the general formula (III) described in the above item (3) are each independently a hydrogen atom, a methyl group, an ethyl group or a phenyl group ( However, it is preferable that R ³ and R ⁴ are hydrogen atoms at the same time).

(5) The general formula (III) described in the above item (3)
The benzothiazole compound represented by
Methylbenzothiazolyl-2) disulfide, bis-
It is preferably at least one selected from the group consisting of (5-methylbenzothiazolyl-2) disulfide, mercapto-4-methylbenzothiazole and mercapto-5-methylbenzothiazole.

(6) The general formula (IV) described in the above item (3),
The position of the alkoxy group of the benzothiazole compound represented by (V) or (VI) in the aromatic monocycle is preferably the 4-position or 6-position, and more preferably the 4-position.

(7) General formula (IV) described in the above item (3),
The alkoxy group of the benzothiazole compound represented by (V) and (VI) is preferably a group selected from the group consisting of a methoxy group, an ethoxy group and a butoxy group, and more preferably an ethoxy group.

(8) The rubber composition according to the above item (1) or (3) has a rubber component having an amount of bound styrene of 30.
It is preferable to contain styrene butadiene copolymer rubber in an amount of at least% by weight.

As described above, the present invention is particularly characterized by using aluminum hydroxide in combination with a specific vulcanization accelerator.

That is, (1) the vulcanization accelerator represented by the formulas (I) to (VI) suppresses the curing due to the heat history due to the running of the tire, so that the softness of the tread rubber composition is maintained. (2) The effect of aluminum hydroxide on improving the tire maneuverability increases as the tread rubber composition is softer.

More specifically, as described in the above (1) and (2), the rubber composition is usually heat-aged and hardened. When aluminum hydroxide is present in the kept rubber composition, the maneuverability of the tire is significantly improved as compared to the case where aluminum hydroxide is simply used or the case where only the specific vulcanization accelerator is used alone. . That is, a new finding that synergistically excellent maneuverability is exhibited by the combined use of aluminum hydroxide and a specific vulcanization accelerator has been obtained, and the pneumatic tire of the present invention has been obtained.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The tread of a tire used in the present invention may be a single layer, or two layers of a cap rubber disposed radially outward and a base rubber disposed radially inward, or a further multilayer. May be configured. When the tread is composed of two or more layers, the rubber composition is more preferably applied to at least the base rubber, and further preferably applied to both the cap rubber and the base rubber or the base rubber.

The tread rubber should contain at least 50 parts by weight, preferably at least 70 parts by weight, of styrene-butadiene copolymer rubber (SBR) per 100 parts by weight of the rubber component. If the blending amount of SBR is less than 50 parts by weight, the handling property and the riding comfort are inferior. This SB
R is selected so that the total amount of bound styrene in the rubber component is at least 20% by weight, preferably 25 to 40% by weight.
It is necessary to incorporate BR. If the total amount of bound styrene is less than 20% by weight, the wet skid performance is reduced. On the other hand, if it exceeds 40% by weight, rolling resistance tends to increase and abrasion resistance tends to decrease, which is not preferable. As for the total bound styrene amount, for example, when 50 parts by weight of one kind of SBR and 50 parts by weight of natural rubber of another rubber component are blended, the bound styrene amount of this SBR is 40 parts by weight.
Weight percent or more.

The amount of bound styrene as a rubber component is 3
It is preferable to contain 0% by weight or more of SBR. However, for example, SBR having an amount of bound styrene of 35% by weight is 10
4 parts by weight of SBR containing 23.5% by weight of bound styrene
In the case where 0 parts by weight and 50 parts by weight of natural rubber are blended, such a blending is not included in the present invention because the styrene unit in the total rubber component is less than 20% by weight.

The SBR used in the present invention is not limited as long as it satisfies the above conditions, and commercially available emulsion-polymerized SBR, solution-polymerized SBR and the like can be used.

In the present invention, examples of the rubber component include natural rubber and synthetic rubber such as isoprene rubber, butadiene rubber, butyl rubber (including halogenated butyl rubber), and ethylene-propylene rubber, in addition to the above SBR.

In the present invention, aluminum hydroxide [Al (OH) ₃ ] is used with respect to 100 parts by weight of the rubber component.
It is used in an amount of 5 to 40 parts by weight, preferably 10 to 30 parts by weight. If the amount is less than 5 parts by weight, the effect of improving the steerability of the tire is reduced, and if it is more than 40 parts by weight, the wear resistance is undesirably reduced. The average particle size of the aluminum hydroxide is preferably 0.01 to 10 μm, and 0.01 to 10 μm.
2 μm is more preferred. If the particle size is less than 0.01 μm, the kneading workability decreases, and if it exceeds 10 μm, the breaking resistance, particularly the wear resistance, of the tread rubber decreases, which is not preferable.

The dithiophosphate compound used in one embodiment of the present invention is a metal dithiophosphate represented by the above general formula (I), O, O'-dialkyldithiophosphate disulfide and O, O'-dialkyldithiophosphate tetrasulfide. It is at least one selected from the group consisting of sulfides. It is preferable to use a dithiophosphoric acid type vulcanization accelerator.

R ¹ and R ² of the metal dithiophosphate represented by the above general formula (I) are each independently a C 1-8.
An alkyl group or an aryl group having 6 to 10 carbon atoms,
This alkyl group may be linear, branched or cyclic. M ¹ is a Zn atom, Sb atom, Fe atom or Cu atom, and n is the number of valences of the metal to be bonded. Among them, R ¹ and R ² are preferably an alkyl group having 3 to 4 carbon atoms. Metal dithiophosphates having an alkyl group having 2 or less carbon atoms tend to have low solubility in rubber, and if the number of carbon atoms is 5 or more, the effect cannot be further improved. Is not always effective. As the metal, a Zn atom or an Sb atom is preferable. That is, a metal dithiophosphate represented by the formula (II) is preferable.

That is, these metal dithiophosphates include, for example, zinc O, O'-dipropyldithiophosphate, zinc O, O'-diisopropyldithiophosphate,
O'-di-n-butyl zinc dithiophosphate, O, O'-di-sec-butyl zinc dithiophosphate, O, O'-di-t
-Butyldithiophosphate, zinc O, O'-diphenyldithiophosphate, zinc O, O'-dicyclohexyldithiophosphate, antimony O, O'-dipropyldithiophosphate, antimony O, O'-diisopropyldithiophosphate, O, O Antimony '-di-n-butyldithiophosphate, antimony O, O'-di-sec-butyldithiophosphate, antimony O, O'-di-t-butyldithiophosphate, antimony O, O'-diphenyldithiophosphate
O, O'-dicyclohexylantimony dithiophosphate and the like, among which zinc O, O'-diisopropyldithiophosphate, O, O'-di-n-butyldithiophosphate zinc, O, O'-diisopropyldithiophosphate antimony, Antimony O, O'-di-n-butyldithiophosphate is preferred. These compounds can be used alone or in a mixture of two or more.

Examples of the O, O'-dialkyldithiophosphate disulfide or O, O'-dialkyldithiophosphate tetrasulfide include, for example, O, O'-dibutyldithiophosphate disulfide, O, O'-diisopropyldithiophosphate disulfide, O, O O'-dipropyldithiophosphate disulfide, O, O'-diethyldithiophosphate disulfide, O, O'-dimethyldithiophosphate disulfide, O, O'-bis (2-ethylhexyl) dithiophosphate disulfide, O, O'-bis (4-methylpentyl) dithiophosphate disulfide, O, O'-dioctadecyldithiophosphate disulfide, O, O'-dibutyldithiophosphate tetrasulfide, O, O'-diisopropyldithiophosphate tetrasulfide, O, O'-dipropyl Dithiophosphoric acid tetrasulfide, O, O′-diethyldithiophosphate tetrasulfide, O, O′-dimethyldithiophosphate tetrasulfide, O, O′-bis (2-ethylhexyl) dithiophosphate tetrasulfide, O,
O'-bis (4-methylpentyl) dithiophosphate tetrasulfide, O, O'-dioctadecyldithiophosphate tetrasulfide and the like can be mentioned. Above all, from the point of effect,
O, O'-dibutyldithiophosphoric acid tetrasulfide,
O, O'-diisopropyldithiophosphate tetrasulfide and O, O'-bis (2-ethylhexyl) dithiophosphate tetrasulfide are preferred.

The dithiophosphoric acid compound should be contained in an amount of 0.2 to 10.0 parts by weight, preferably 0.5 to 5.0 parts by weight, based on 100 parts by weight of the rubber component.
If it is less than 0.2 parts by weight, the controllability improvement effect after traveling is low,
Even if the amount is more than 10.0 parts by weight, no further improvement in the effect is recognized, and further increase in the amount is not effective from an economic viewpoint.

The benzothiazole compound used in another embodiment of the present invention is a compound represented by the above general formula (III), (IV) or (V)
And at least one selected from the group consisting of the compounds represented by (VI). Benzothiazole vulcanization accelerators are preferred.

The above general formula (III) used in the present invention
R ³ and R ⁴ of the benzothiazole compound represented by are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or 6 to 10 carbon atoms, except when they are simultaneously hydrogen atoms.
Preferably a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms, each being a hydrogen atom, a methyl group, an ethyl group or a phenyl group. More preferred.

These compounds include, for example, 2-mercapto-4-methylbenzothiazole, 2-mercapto-4-ethylbenzothiazole, 2-mercapto-5
-Methylbenzothiazole, 2-mercapto-5-ethylbenzothiazole, 2-mercapto-6-methylbenzothiazole, 2-mercapto-6-ethylbenzothiazole, 2-mercapto-4,5-dimethylbenzothiazole, 2-mercapto -4,5-diethylbenzothiazole, 2-mercapto-4-phenylbenzothiazole, 2-mercapto-5-phenylbenzothiazole,
2-mercapto-6-phenylbenzothiazole, bis- (4-methylbenzothiazolyl-2) disulfide,
Bis- (4-ethylbenzothiazolyl-2) disulfide, bis- (5-methylbenzothiazolyl-2) disulfide, bis- (5-ethylbenzothiazolyl-2) disulfide, bis- (6- Methylbenzothiazolyl-
2) disulfide, bis- (6-ethylbenzothiazolyl-2) disulfide, bis- (4,5-dimethylbenzothiazolyl-2) disulfide, bis- (4,5-diethylbenzothiazolyl-2) ) Disulfide, bis-
(4-phenylbenzothiazolyl-2) disulfide,
Bis- (5-phenylbenzothiazolyl-2) disulfide, bis- (6-phenylbenzothiazolyl-2) disulfide and the like can be mentioned. Among them, bis- (4-methylbenzothiazolyl-2) disulfide, bis- (5-methylbenzothiazolyl-2) disulfide, 2-mercapto-4-methylbenzothiazole and 2-mercapto-5-methylbenzothiazole Is preferred. These compounds can be used alone or in a mixture of two or more.

The method for producing these compounds is not particularly limited, but they can be easily produced by using, for example, JP-A-49-93361.

The above general formula (IV) used in the present invention,
The benzothiazole compound represented by (V) or (VI) is a 2-mercaptobenzothiazole compound containing an alkoxy group, and is used alone or in a mixture of two or more.

Where R^FiveIs an alkyl group having 1 to 8 carbon atoms,
Represents an alkenyl group or a cycloalkyl group;⁶Is hydrogen
Atom or -N (R⁷) R⁸Represents an amino group represented by
R⁷And R⁸Are each independently a hydrogen atom or 2 to 2 carbon atoms
4 represents an alkyl group or a cyclohexyl group (provided that
R⁷And R⁸Are simultaneously hydrogen atoms). R
⁹And R^TenIs independently alkyl having 1 to 8 carbon atoms
Represents an alkenyl group or a cycloalkyl group. X is Z
n atom, Cu atom or> NR¹³The amino group represented by
Represents, R¹³Is an alkyl group having 2 to 4 carbon atoms or cyclohexyl
Represents a sil group. R ¹¹And R¹²Is R⁹Is synonymous with

In these general formulas, the alkoxy groups -OR ⁵ , -OR ⁹ , -OR ¹⁰ , -OR ¹¹ and -OR ¹²
Each group is preferably independently a methoxy group, an ethoxy group or a butoxy group from the viewpoint of the effect, and more preferably an ethoxy group.

Examples of the benzothiazole compound represented by the general formula (IV) include, for example, 4-methoxy-2-mercaptobenzothiazole, 5-methoxy-2-mercaptobenzothiazole, 6-methoxy-2-mercaptobenzothiazole 7-methoxy-2-mercaptobenzothiazole, 4-ethoxy-2-mercaptobenzothiazole, 5-ethoxy-2-mercaptobenzothiazole, 6-ethoxy-2-mercaptobenzothiazole,
7-ethoxy-2-mercaptobenzothiazole, 4-
Butoxy-2-mercaptobenzothiazole, 5-butoxy-2-mercaptobenzothiazole, 6-butoxy-2-mercaptobenzothiazole, 7-butoxy-2
-Mercaptobenzothiazole, N-tert-butyl-4-methoxy-2-benzothiazolylsulfenamide, N-tert-butyl-5-methoxy-2-benzothiazolylsulfenamide, N-tert-butyl-
6-methoxy-2-benzothiazolylsulfenamide, N-tert-butyl-7-methoxy-2-benzothiazolylsulfenamide, N-tert-butyl-
4-ethoxy-2-benzothiazolylsulfenamide, N-tert-butyl-5-ethoxy-2-benzothiazolylsulfenamide, N-tert-butyl-
6-ethoxy-2-benzothiazolylsulfenamide, N-tert-butyl-7-ethoxy-2-benzothiazolylsulfenamide, N-tert-butyl-
4-butoxy-2-benzothiazolylsulfenamide, N-tert-butyl-5-butoxy-2-benzothiazolylsulfenamide, N-tert-butyl-
6-butoxy-2-benzothiazolylsulfenamide, N-tert-butyl-7-butoxy-2-benzothiazolylsulfenamide, N-ethyl-4-methoxy-2-benzothiazolylsulfenamide, N -Ethyl-5-methoxy-2-benzothiazolylsulfenamide, N-ethyl-6-methoxy-2-benzothiazolylsulfenamide, N-ethyl-7-methoxy-2-
Benzothiazolylsulfenamide, N-ethyl-4-
Ethoxy-2-benzothiazolylsulfenamide, N
-Ethyl-5-ethoxy-2-benzothiazolylsulfenamide, N-ethyl-6-ethoxy-2-benzothiazolylsulfenamide, N-ethyl-7-ethoxy-2-benzothiazolylsulfenamide, N-ethyl-4-butoxy-2-benzothiazolylsulfenamide, N-ethyl-5-butoxy-2-benzothiazolylsulfenamide, N-ethyl-6-butoxy-2-benzothiazolylsulfenamide N-ethyl-7-butoxy-2-benzothiazolylsulfenamide, N-
Cyclohexyl-4-methoxy-2-benzothiazolylsulfenamide, N-cyclohexyl-5-methoxy-2-benzothiazolylsulfenamide, N-cyclohexyl-6-methoxy-2-benzothiazolylsulfenamide, N -Cyclohexyl-7-methoxy-2-
Benzothiazolylsulfenamide, N-cyclohexyl-4-ethoxy-2-benzothiazolylsulfenamide, N-cyclohexyl-5-ethoxy-2-benzothiazolylsulfenamide, N-cyclohexyl-6
-Ethoxy-2-benzothiazolylsulfenamide,
N-cyclohexyl-7-ethoxy-2-benzothiazolylsulfenamide, N-cyclohexyl-4-butoxy-2-benzothiazolylsulfenamide, N-cyclohexyl-5-butoxy-2-benzothiazolylsulfenamide , N-cyclohexyl-6-butoxy-
2-benzothiazolylsulfenamide, N-cyclohexyl-7-butoxy-2-benzothiazolylsulfenamide, N, N-dicyclohexyl-4-methoxy-
2-benzothiazolylsulfenamide, N, N-dicyclohexyl-5-methoxy-2-benzothiazolylsulfenamide, N, N-dicyclohexyl-6-methoxy-2-benzothiazolylsulfenamide, N, N
-Dicyclohexyl-7-methoxy-2-benzothiazolylsulfenamide, N, N-dicyclohexyl-4
-Ethoxy-2-benzothiazolylsulfenamide,
N, N-dicyclohexyl-5-ethoxy-2-benzothiazolylsulfenamide, N, N-dicyclohexyl-6-ethoxy-2-benzothiazolylsulfenamide, N, N-dicyclohexyl-7-ethoxy-2-
Benzothiazolylsulfenamide, N, N-dicyclohexyl-4-butoxy-2-benzothiazolylsulfenamide, N, N-dicyclohexyl-5-butoxy-2-benzothiazolylsulfenamide, N, N-dicyclohexyl -6-butoxy-2-benzothiazolylsulfenamide, N, N-dicyclohexyl-7-butoxy-2-benzothiazolylsulfenamide, and the like.

Examples of the benzothiazole compound represented by the general formula (V) include di-4-methoxy-2-benzothiazolyl disulfide, di-5-methoxy-2-benzothiazolyl disulfide, 6-methoxy-2-
Benzothiazolyl disulfide, di-7-methoxy-2
-Benzothiazolyl disulfide, di-4-ethoxy-
2-benzothiazolyl disulfide, di-5-ethoxy-2-benzothiazolyl disulfide, di-6-ethoxy-2-benzothiazolyl disulfide, di-7-ethoxy-2-benzothiazolyl disulfide, Di-4-butoxy-2-benzothiazolyl disulfide, di-5
Butoxy-2-benzothiazolyl disulfide, di-6
-Butoxy-2-benzothiazolyl disulfide, di-
7-butoxy-2-benzothiazolyl disulfide, and the like.

Examples of the benzothiazole compound represented by the general formula (VI) include 4-methoxy-2-mercaptobenzothiazole zinc salt, 5-methoxy-2-mercaptobenzothiazole zinc salt and 6-methoxy-2 −
Mercaptobenzothiazole zinc salt, 7-methoxy-2
-Zinc mercaptobenzothiazole, 4-ethoxy-
2-mercaptobenzothiazole zinc salt, 5-ethoxy-2-mercaptobenzothiazole zinc salt, 6-ethoxy-2-mercaptobenzothiazole zinc salt, 7-ethoxy-2-mercaptobenzothiazole zinc salt, 4-butoxy-2- Mercaptobenzothiazole zinc salt, 5-
Butoxy-2-mercaptobenzothiazole zinc salt, 6
-Butoxy-2-mercaptobenzothiazole zinc salt,
7-butoxy-2-mercaptobenzothiazole zinc salt, 4-methoxy-2-mercaptobenzothiazole copper salt, 5-methoxy-2-mercaptobenzothiazole copper salt, 6-methoxy-2-mercaptobenzothiazole copper salt, 7- Methoxy-2-mercaptobenzothiazole copper salt, 4-ethoxy-2-mercaptobenzothiazole copper salt, 5-ethoxy-2-mercaptobenzothiazole copper salt, 6-ethoxy-2-mercaptobenzothiazole copper salt, 7-ethoxy- 2-mercaptobenzothiazole copper salt, 4-butoxy-2-mercaptobenzothiazole copper salt, 5-butoxy-2-mercaptobenzothiazole copper salt, 6-butoxy-2-mercaptobenzothiazole copper salt, 7-butoxy-2- Mercaptobenzothiazole copper salt, N-ethyl- ( - methoxy-2-benzothiazolyl) sulfenimides, N- ethyl - (5-methoxy -
2-benzothiazolyl) sulfenimide, N-ethyl- (6-methoxy-2-benzothiazolyl) sulfenimide, N-ethyl- (7-methoxy-2-benzothiazolyl) sulfenimide, Nt-butyl (4- Methoxy-2-benzothiazolyl) sulfenimide, N-
t-butyl (5-methoxy-2-benzothiazolyl) sulfenimide, Nt-butyl (6-methoxy-2-
Benzothiazolyl) sulfenimide, Nt-butyl (7-methoxy-2-benzothiazolyl) sulfenimide, N-cyclohexyl (4-methoxy-2-benzothiazolyl) sulfenimide, N-cyclohexyl (5-methoxy-2- Benzothiazolyl) sulfenimide, N-cyclohexyl (6-methoxy-2-benzothiazolyl) sulfenimide, N-cyclohexyl (7-methoxy-2-benzothiazolyl) sulfenimide, N-ethyl- (4-ethoxy-2-benzothiazolyl) ) Sulfenimide, N-ethyl- (5-ethoxy-2-benzothiazolyl) sulfenimide, N-ethyl- (6-ethoxy-2-benzothiazolyl) sulfenimide, N-ethyl- (7-ethoxy-2- Benzothiazolyl) sulfene Bromide, N-t-butyl (4-ethoxy-2-benzothiazolyl) sulfenimides, N
-T-butyl (5-ethoxy-2-benzothiazolyl)
Sulfenimide, Nt-butyl (6-ethoxy-2
-Benzothiazolyl) sulfenimide, Nt-butyl (7-ethoxy-2-benzothiazolyl) sulfenimide, N-cyclohexyl (4-ethoxy-2-benzothiazolyl) sulfenimide, N-cyclohexyl (5-ethoxy-2) -Benzothiazolyl) sulfenimide, N-cyclohexyl (6-ethoxy-2-benzothiazolyl) sulfenimide, N-cyclohexyl (7-ethoxy-2-benzothiazolyl) sulfenimide, N-ethyl- (4-butoxy-2-) Benzothiazolyl) sulfenimide, N-ethyl- (5-butoxy-2-benzothiazolyl) sulfenimide, N-ethyl- (6-butoxy-2-benzothiazolyl) sulfenimide, N-ethyl- (7-butoxy-2) -Benzothiazolyl) sulfe Imide, N-t-butyl (4-butoxy-2-benzothiazolyl) sulfenimides, N
-T-butyl (5-butoxy-2-benzothiazolyl)
Sulfenimide, Nt-butyl (6-butoxy-2
-Benzothiazolyl) sulfenimide, Nt-butyl (7-butoxy-2-benzothiazolyl) sulfenimide, N-cyclohexyl (4-butoxy-2-benzothiazolyl) sulfenimide, N-cyclohexyl (5-butoxy-2) -Benzothiazolyl) sulfenimide, N-cyclohexyl (6-butoxy-2-benzothiazolyl) sulfenimide, N-cyclohexyl (7-butoxy-2-benzothiazolyl) sulfenimide, and the like.

Among these benzothiazole compounds,
The position of the alkoxy group contained in the general formulas (IV), (V) and (VI) on the aromatic monocycle is preferably the 4-position or 6-position, more preferably the 4-position. In addition, a benzothiazole compound having an alkoxy group at the 4- or 6-position of the aromatic monocycle is preferable in terms of availability of raw materials and ease of synthesis. In addition, aromatic monocyclic 4
Benzothiazolylsulfenamide, benzothiazolyl disulfide and benzothiazolylsulfenimide having an alkoxy group at the 6-position or 6-position are also preferable in view of scorch properties. Further, a compound having an alkoxy group at the 4-position of the aromatic monocyclic ring is more preferable because it suppresses curing during thermal aging of the rubber composition.

The production method of these compounds is not particularly limited, but they can be easily produced by using, for example, JP-A-49-93361.

The amount of the benzothiazole compound used in the present invention is from 0.2 to 100 parts by weight of the rubber component.
10 parts by weight, preferably 0.5 to 5.0 parts by weight,
If the amount is less than 0.2 parts by weight, a sufficient effect cannot be obtained.
If the amount exceeds 10 parts by weight, not only no further effect can be obtained, but also the workability such as scorch properties deteriorates.

These compounds used in the present invention include, in addition to the above, general-purpose vulcanization accelerators such as 2-mercaptobenzothiazyldisulfide, Nt-butylbenzothiazolylsulfenamide, and N-cyclohexylbenzothiazolylsulfur. A thiazole compound such as phenamide or a thiuram compound such as tetra (2-ethylhexyl) thiuram disulfide or tetramethylthiuram disulfide can be appropriately compounded.

Carbon black, silica, zinc oxide, stearic acid, an antioxidant, W which is commonly used together with the above essential components as the rubber composition for a pneumatic tire of the present invention.
Components such as AX, a silane coupling agent, and a vulcanizing agent can be appropriately compounded as long as the effects of the present invention are not impaired.

Examples of the vulcanizing agent include sulfur and the like, and its amount is 0.1 to 5 parts by weight, preferably 1 to 2 parts by weight, based on 100 parts by weight of the rubber component. If the amount is less than 0.1 part by weight, the breaking strength and abrasion resistance of the vulcanized rubber decrease, and if it exceeds 5 parts by weight, the rubber elasticity is impaired.

The rubber composition for a pneumatic tire of the present invention comprises:
It is obtained by kneading using a kneading machine such as a roll, an internal mixer, a Banbury mixer, and the like, and after forming, vulcanized and used for a tire tread and the like.

[0051]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the present invention.

The physical properties of the vulcanized rubber were measured according to the following methods. (1) Wet skid performance (grip property on wet road surface) Wet skid performance was measured using a British Standard Portable Skid Tester (manufactured by Stanley London Co.), and the index was expressed as an index with Example 5 being 100. The larger the value, the better the wet skid performance. (2) Rolling Resistance Using a spectrometer manufactured by Toyo Seiki Co., Ltd., the reciprocal of the value of tan δ when measured under the conditions of a dynamic strain amplitude of 0.1%, a frequency of 52 Hz, and a measurement temperature of 60 ° C. was measured. 5 to 1
The index was indicated as 00. The higher the value, the better. (3) Wear resistance Using a Lambourn-type abrasion tester, a slip ratio of 2 at room temperature was used.
The test was performed under the condition of 5%, and the reciprocal of the abrasion amount was set to 100 in Example 5 as an index. The higher the value, the better. (4) Maneuverability (wet steering stability) Using a FF4 door sedan on a test course, driving on a wet asphalt road using a real vehicle, and testing the driveability, braking, steering wheel responsiveness, and steering controllability. The driver made a comprehensive evaluation and evaluated the maneuverability of the new tire. In addition, the same tire can be used for general markets of 20,000 km.
After running, the steering performance of the running tire was evaluated.

The evaluation results are shown in Examples 1 and 2,
The new tires and running tires of Comparative Examples 2, 3, 4, 5 and 6, and the running tires of Comparative Example 1 were all controlled using the new tire of Comparative Example 1 and Examples 3, 4, 6 and 7 respectively. In each of the new tires and running tires of Comparative Examples 7 to 11, and the running tire of Example 5, the difference between the control and the new tire of Example 5 was indicated by ± values. The larger the value of +, the better the performance. Where ±
0 means that the test driver cannot detect the difference in performance between the control tires, +1 means that the test driver has excellent performance to detect a significant difference in performance between the control tires, and +2 means that the test driver can clearly detect the difference. +3 means that the test driver can detect the difference in performance very clearly, and +4 means that the driver has a clear difference in performance. Indicates that the performance is excellent to the extent that it can be detected. The larger the value of-, the lower the performance. -1, -2, -3,
The degree of inferiority of -4 corresponds to the case where "excellent" is read as "inferior" in accordance with the above numerical value of +.

[Examples 1 and 2, Comparative Examples 1 to 6] Kneading and compounding were performed according to the compounding recipe shown in Table 1 below, and this tread rubber compound was vulcanized at 150 ° C for 30 minutes.
Using the same composition, a tire of 195 / 60R14 size was prototyped, and the performance of the tire was measured. Table 1 shows the results.

[0055]

[Table 1]

The description of the numbering in Table 1 is shown below. 1) SBR # 1500 (23.5% by weight of bound styrene, J
2) SBR # 0120 (Bound styrene content 35% by weight, 37.5
3) Carbon black: ISAF, SEAST 7H (manufactured by Tokai Carbon Co., Ltd.) 4) TMDQ: 2,2,4-trimethyl-1,2-dihydroquinoline polymer 5) IPPD : N-isopropyl-N'-phenyl-p
-Phenylenediamine 6) Heidilite 43M (manufactured by Showa Denko KK, average particle size 0.6 μm) 7) MBTS: bis- (benzothiazolyl-2) disulfide 8) DPG: diphenylguanidine 9) MMBTS: bis- (4- Methylbenzothiazolyl-2) disulfide 10) TBBS: Nt-butyl-2-benzothiazolylsulfenamide 11) DIPDPZn: zinc O, O'-diisopropyldithiophosphate 12)% by weight in rubber component Examples 3 to 7 and Comparative Examples 7 to 11] A common formulation for each of Examples and Comparative Examples was 20 parts by weight of aroma oil, 2.0 parts by weight of wax, 2,2,4-trimethyl-1,2-dihydroquinoline. 0.5 parts by weight of polymer, N-isopropyl-
N'phenyl-p-phenylenediamine 1.0 part by weight,
Using 1.0 part by weight of stearic acid, 3.0 parts by weight of zinc white and 1.8 parts by weight of sulfur, and a composition having the composition shown in Tables 2 and 3 was vulcanized at 150 ° C. for 30 minutes. Also,
A tire of 195 / 60R14 size was prototyped using the same composition. The physical properties of the vulcanized rubber thus obtained and the wet handling of the tire were evaluated. The results are shown in Tables 2 and 3.

[0057]

[Table 2]

[0058]

[Table 3]

The description of the numbering in Tables 2 and 3 is shown below. 1) SBR # 1500 (23.5% by weight of bound styrene, J
2) SBR # 0120 (Bound styrene content 35% by weight, 37.5
3) Heidilite 43M (manufactured by Showa Denko KK, average particle diameter 0.6 μm) 4) Nipsil AQ (manufactured by Nippon Silica Co., Ltd., BET value 1)
95m ² / g) 5) Seast KH (Tokai Carbon Co., Ltd., BET value 9)
^{3m 2 / g) 6) Si69} ( Degussa, bis (3-triethoxysilylpropyl) tetrasulfide) 7) MBTS: bis - (benzothiazolyl -2) disulfide 8) DPG: diphenylguanidine 9) MMBTS: bis - ( 4-methylbenzothiazolyl-2) disulfide 10) TBBS: Nt-butyl-2-benzothiazolylsulfenamide 11) DIPDPZn: zinc O, O'-diisopropyldithiophosphate 12) DBDPZn: O, O ' -Zinc di-n-butyldithiophosphate 13) DEBTS: di-4-ethoxy-2-benzothiazolyl disulfide 14)% by weight in rubber component As shown in Tables 1-3, the pneumatic tire of the present invention Is to maintain a high level of maneuverability of running tires from mid-running onwards with respect to the maneuverability of new tires (before running). Can.

When neither the aluminum hydroxide according to the present invention nor the compound according to the present invention is used (Comparative Example 1), the case where only the benzothiazole compound according to the present invention is used without using aluminum hydroxide ( Comparative Example 2) In the case where only the dithiophosphoric acid-based compound according to the present invention is used without using aluminum hydroxide (Comparative Example 3),
When only the aluminum hydroxide was used without using the compound according to the present invention (Comparative Example 4), the SBR in the rubber component was used using the dithiophosphoric acid-based compound according to the present invention regardless of the presence or absence of aluminum hydroxide. When the total bound styrene content of is outside the range of the present invention (less than 20% by weight) (Comparative Examples 5 and 6)
In any case, the maneuverability of the tire after the middle stage of running is deteriorated.
On the other hand, when the aluminum hydroxide according to the present invention and the dithiophosphoric acid-based or benzothiazole-based compound are used in combination and the total bound styrene content of SBR in the rubber component is 20% by weight or more (Examples 1 and 2), It can be seen that the maneuverability is maintained at a high level even after the middle stage of driving. Examples 3 to
7. From Comparative Examples 7 to 11, it can be seen that the same effect is obtained even with the silica-containing system.

[0061]

As described above, the pneumatic tire of the present invention has an excellent effect of maintaining a high level of maneuverability from the early stage of running to the middle stage and thereafter.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 21/00 C08L 21/00

Claims (8)

[Claims] The rubber composition in the tread portion is a rubber component 1
5 parts by weight of styrene-butadiene copolymer rubber
0 parts by weight or more, the total bound styrene content in the rubber component is 20% by weight or more, aluminum hydroxide is contained in 5 to 40 parts by weight with respect to 100 parts by weight of the rubber component, and the following general formula (I) )) At least one dithiophosphoric compound selected from the group consisting of a metal dithiophosphate, O, O'-dialkyldithiophosphate disulfide and O, O'-dialkyldithiophosphate tetrasulfide represented by the following formula: A pneumatic tire having a tread portion composed of a rubber composition containing 0.2 to 10.0 parts by weight with respect to a portion. Embedded image (Wherein, R ¹ and R ² are each independently a C 1-8
Represents an alkyl group or an aryl group having 6 to 10 carbon atoms.
This alkyl group may be linear, branched or cyclic. M ¹ represents a Zn atom, an Sb atom, an Fe atom or a Cu atom, and n represents the number of valences of the metal to be bonded. ) 2. The pneumatic tire according to claim 1, wherein the metal dithiophosphate represented by the general formula (I) is a dithiophosphate-based compound represented by the following general formula (II). Embedded image (In the formula, M ² represents a Zn atom or an Sb atom, and n represents the number of valences of the metal to be bonded.) 3. The rubber composition of the tread portion, wherein the rubber component 1
5 parts by weight of styrene-butadiene copolymer rubber
0 parts by weight or more, the total bound styrene content in the rubber component is 20% by weight or more, aluminum hydroxide is contained in 5 to 40 parts by weight with respect to 100 parts by weight of the rubber component, and the following general formula (III) ), (IV),
A rubber containing 0.2 to 10.0 parts by weight of at least one benzothiazole compound selected from the group consisting of the compounds represented by (V) and (VI) based on 100 parts by weight of the rubber component. A pneumatic tire having a tread portion composed of a composition. Embedded image Embedded image Embedded image Embedded image (Wherein, R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 10 carbon atoms, provided that R ³ and R ⁴ are simultaneously a hydrogen atom. unless .R ⁵ represents an alkyl group having 1 to 8 carbon atoms, an alkenyl group or a cycloalkyl group, R ⁶ represents an amino group represented by hydrogen or ^{-N (R 7) R 8,} R 7 and R ⁸ each independently represent a hydrogen atom or an alkyl group or a cyclohexyl group having 2 to 4 carbon atoms. However, .R ⁹ and R ¹⁰ except when R ⁷ and R ⁸ are not hydrogen atoms at the same time
Each independently represents an alkyl group, alkenyl group or cycloalkyl group having 1 to 8 carbon atoms. X is a Zn atom, Cu
An amino group represented by atom or> N-R ^13, R ¹³ represents an alkyl group or a cyclohexyl group having 2 to 4 carbon atoms. R ¹¹ and R ¹² have the same meaning as R ⁹ . ) 4. The benzothiazole compound represented by the general formula (III) according to claim 3, wherein R ³ and R ⁴ are each independently a hydrogen atom, a methyl group, an ethyl group or a phenyl group ( ^4. The pneumatic tire according to claim ³ , wherein R ³ and R ⁴ are hydrogen atoms at the same time). 5. The benzothiazole compound represented by the general formula (III) according to claim 3, wherein bis- (4-methylbenzothiazolyl-2) disulfide, bis- (5-
Methylbenzothiazolyl-2) disulfide, mercapto-4-methylbenzothiazole and mercapto-5
The pneumatic tire according to claim 3, wherein the pneumatic tire is at least one selected from the group consisting of methylbenzothiazole. 6. The general formula (IV) or (V) according to claim 3,
4. The pneumatic tire according to claim 3, wherein the position of the alkoxy group of the benzothiazole compound represented by (VI) in the aromatic monocycle is the 4-position or the 6-position. 7. The general formula (IV) or (V) according to claim 3,
4. The pneumatic tire according to claim 3, wherein the alkoxy group of the benzothiazole compound represented by (VI) is a group selected from the group consisting of a methoxy group, an ethoxy group and a butoxy group. 8. The rubber composition according to claim 1, wherein the rubber component contains a styrene-butadiene copolymer rubber having a bound styrene content of 30% by weight or more as a rubber component.
The pneumatic tire as described.