JP2003238735A - Rubber composition and pneumatic tire produced by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a rubber composition which exhibits excellent griping performance without reducing productivity, and to provide a pneumatic tire made by using the same. <P>SOLUTION: The rubber composition is obtained by blending 100 pts.wt. of a rubber component comprising a natural rubber and/or a synthetic rubber, 0.1-50 pts.wt. of a benzimidazole derivative represented by formula (I) (wherein R<SP>1</SP>is a 1-18C hydrocarbon group, a heterocyclic group, an acyl, an amido, a sulfonyl, hydroxy or nitro; and R<SP>2</SP>to R<SP>6</SP>are each independently H, a halogen atom, a 1-18C hydrocarbon group, a heterocyclic group, hydroxy, an alkoxyl, a substituted or unsubstituted amino, amido, nitro, a substituted or unsubstituted mercapto, sulfonyl or an acyl), and 0.1-50 pts.wt. of a protonic acid. The pneumatic tire is produced by using the rubber composition for its member. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a rubber composition and a pneumatic tire using the same. For more details,
The present invention relates to a rubber composition having improved grip performance without impairing productivity, and a pneumatic tire using the rubber composition having improved grip performance in high-speed running and the like.

[0002]

2. Description of the Related Art In recent years, the demand for pneumatic tires having high dynamic performance has increased with the improvement of automobile performance, pavement of roads, and development of highway networks. The higher this characteristic, the faster, more accurate and safer the vehicle can travel. Above all, grip performance represented by acceleration performance and braking performance is an important required characteristic. Conventionally, as a method for obtaining a high grip performance, a method of using a styrene-butadiene copolymer rubber having a high styrene content, which is a rubber having a high glass transition temperature, in a rubber composition for a tire tread is known. However, according to this method, although the grip performance at around room temperature is improved, there is a disadvantage that the tan δ value is lowered and the grip performance is lowered as the rubber temperature rises due to running.

Further, in order to improve the deterioration of grip performance with temperature rise, a monomer such as 1,3-butadiene, styrene or isoprene and diphenyl-2-methacryloyloxyethyl phosphate or diphenyl-2 are used.
-A technique of using a copolymer rubber obtained by copolymerizing a (meth) acrylate compound having a diphenyl phosphate group such as acryloyloxyethyl phosphate has been disclosed (JP-A-59-187011).
However, in this case, not only is it not applicable to natural rubber, but there is also the disadvantage that depending on the production conditions, the properties inherent to polymers such as styrene-butadiene copolymer rubber and polybutadiene rubber are impaired. On the other hand, there is known a method of increasing the tan δ value of a rubber composition by using a compounding system highly filled with process oil and carbon black. According to this method, although the grip performance is improved, the filling amount is increased. If it is too large, there is a problem that the high filling is limited and the desired high grip performance is difficult to obtain, because the fracture characteristics and the wear resistance are significantly reduced.

Furthermore, by blending a specific imidazole compound and / or imidazoline compound and a specific protonic acid derivative in a rubber component in a predetermined ratio, the tan δ value in a high temperature region is increased, and this rubber composition is used in a tire. A technique for improving the grip performance by using it for the tread has been disclosed (Japanese Patent Laid-Open No. 63-139931). However, this technique has a problem in practical use because of insufficient productivity.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a rubber composition which solves the problems of the prior art and exhibits excellent grip performance without impairing the productivity, and a rubber composition thereof. It is an object of the present invention to provide a pneumatic tire having improved grip performance in high speed running and the like.

[0006]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors have determined that a benzimidazole derivative having a specific structure and a protonic acid are used as rubber components in specific ratios. It has been found that the purpose can be achieved by the compounded composition. The present invention is
It was completed based on this knowledge. That is,
The present invention comprises: (1) 100 parts by weight of a rubber component composed of natural rubber and / or synthetic rubber;

[0007]

[Chemical 2]

(In the formula, R ¹ is a hydrocarbon group having 1 to 18 carbon atoms, a heterocyclic group, an acyl group, an amide group, a sulfonyl group, a hydroxyl group or a nitro group, and R ^{2 to} R ⁶ are independently hydrogen. Atom, halogen atom, hydrocarbon group having 1 to 18 carbon atoms, heterocyclic group, hydroxyl group, alkoxyl group, substituted or unsubstituted amino group, amide group, nitro group, substituted or unsubstituted mercapto group, sulfonyl group or acyl group The benzimidazole derivative represented by
The present invention provides a rubber composition containing 0 part by weight and 0.1 to 50 parts by weight of a protic acid. The present invention also provides
The present invention also provides a pneumatic tire characterized by using the rubber composition for a rubber member, particularly a tread.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As the rubber component in the rubber composition of the present invention, natural rubber and / or synthetic rubber is used. Here, the synthetic rubber is preferably a diene rubber, for example, a styrene-butadiene copolymer rubber (SB
R), polybutadiene rubber (BR), polyisoprene rubber (IR), acrylonitrile-butadiene copolymer rubber (NBR) and the like, and other butyl rubber (II
R), ethylene-propylene copolymer rubber and the like. Further, those having a branched structure, which are obtained by using a polyfunctional modifier such as tin tetrachloride, can also be used. These natural rubbers and synthetic rubbers may be used alone or in combination of two or more. The rubber composition of the present invention has the general formula (I)

[0010]

[Chemical 3]

(In the formula, R ¹ is a hydrocarbon group having 1 to 18 carbon atoms, a heterocyclic group, an acyl group, an amide group, a sulfonyl group, a hydroxyl group or a nitro group, and R ^{2 to} R ⁶ are independently hydrogen. Atom, halogen atom, hydrocarbon group having 1 to 18 carbon atoms, heterocyclic group, hydroxyl group, alkoxyl group, substituted or unsubstituted amino group, amide group, nitro group, substituted or unsubstituted mercapto group, sulfonyl group or acyl group The benzimidazole derivative represented by

In the general formula (I), the hydrocarbon group having 1 to 18 carbon atoms in R ¹ and the hydrocarbon group having 1 to 18 carbon atoms in R ^{2 to} R ⁶ include 1 to 1 carbon atoms. 18 alkyl group, C2-C18 alkenyl group, C2-C2
Examples thereof include an alkynyl group having 18 carbon atoms, an aryl group having 6 to 18 carbon atoms and an aralkyl group having 7 to 18 carbon atoms.
Here, the above-mentioned alkyl group having 1 to 18 carbon atoms and 2 carbon atoms
The alkenyl group having 18 to 18 carbon atoms and the alkynyl group having 2 to 18 carbon atoms may be linear, branched, or cyclic, and at least one selected from sulfur atom, nitrogen atom, and oxygen atom. It may be substituted with one or more substituents containing atoms. Examples of the aforementioned alkyl group, alkenyl group and alkynyl group include a methyl group, an ethyl group,
n-propyl group, isopropyl group, various butyl groups, various pentyl groups, various hexyl groups, various octyl groups, various decyl groups, cyclopentyl groups, cyclohexyl groups, vinyl groups, allyl groups, propenyl groups, ethynyl groups, propynyl groups, etc. Can be mentioned.

The aryl group having 6 to 18 carbon atoms and the aralkyl group having 7 to 18 carbon atoms have at least one atom selected from carbon atom, sulfur atom, nitrogen atom and oxygen atom on the ring. One or more containing substituents may be introduced. Examples of the aryl group and aralkyl group include a phenyl group, a tolyl group, a xylyl group, a naphthyl group, an anthryl group, a trityl group, a benzyl group, a phenethyl group and a naphthylmethyl group. Furthermore, the heterocyclic group of R ¹ and the heterocyclic group of R ^{2 to} R ⁶ have at least one atom selected from a carbon atom, a sulfur atom, a nitrogen atom and an oxygen atom on the ring. One or more containing substituents may be introduced. Examples of the hetero atom constituting the ring of this heterocyclic group include at least one selected from a sulfur atom, a nitrogen atom and an oxygen atom, and the number of members of the ring is about 3 to 10. Examples of such a heterocyclic group include a furyl group,
Thienyl group, pyrrolyl group, oxazolyl group, thiazyl group, imidazolyl group, pyrazolyl group, pyridyl group, pyrimidinyl group, pyrrolidinyl group, piperidyl group, piperazinyl group, morpholinyl group, quinolyl group, quinoxalinyl group, indolyl group, benzofuranyl group, benzothio Examples thereof include a phenyl group.

The acyl group of R ¹ and the acyl group of R ^{2 to} R ⁶ are preferably those having 2 to 18 carbon atoms, and examples thereof include an acetyl group, a propionyl group and a benzoyl group. Examples thereof include formamide group and acetamide group, and examples of sulfonyl group include methanesulfonyl group and ethanesulfonyl group. Of the R ¹ 's described above, an aryl group is preferable, and a phenyl group is particularly preferable. Examples of the halogen atom among R ^{2 to} R ⁶ include fluorine, chlorine, bromine, and iodine, and the alkoxyl group has a carbon number of 1 to 18, such as methoxy group, ethoxy group, n-propoxy group, and iso Examples include propoxy group, various butoxy groups, various pentoxy groups, various hexoxy groups and the like. Further, the substituent of the substituted amino group and the substituted mercapto group among R ^{2 to} R ⁶ has 1 to 18 carbon atoms.
Is preferably an alkyl group such as a methyl group, an ethyl group,
Examples thereof include n-propyl group, isopropyl group, various butyl groups, various pentyl groups, and various hexyl groups. In addition,
The substituted amino group may be mono-substituted or di-substituted.

Examples of the benzimidazole derivative represented by the general formula (I) are 1-phenylbenzimidazole, 1-phenyl-2-methylbenzimidazole, 1-benzylbenzimidazole and 1-benzyl-2. -Methylbenzimidazole, 1-phenyl-2
-Ethylbenzimidazole, 1-benzyl-2-ethylbenzimidazole, 1,2-dimethylbenzimidazole, 1-tert-butyl-2-methylbenzimidazole, 1-trityl-2-methylbenzimidazole, 1-tert-butyl 2-ethylbenzimidazole, 1-trityl-2-ethylbenzimidazole and the like can be preferably mentioned.

In the present invention, the benzimidazole derivative may be used alone or in combination of two or more kinds. Further, the compounding amount is the same as the rubber component 1
It is selected in the range of 0.1 to 50 parts by weight with respect to 00 parts by weight. When this amount is in the range of 0.1 to 50 parts by weight, the desired effect is further exhibited, and when it is 50 parts by weight or less, the physical properties after vulcanization are not adversely affected. For these reasons, the preferred amount is 0.5 to 30 parts by weight, particularly 1 to 20 parts by weight.

The rubber composition of the present invention contains a protic acid. The protonic acid has, for example, 2 to 2 carbon atoms.
20 aliphatic mono- or polycarboxylic acids with 7 to 20 carbon atoms
At least one selected from the aromatic mono- or polycarboxylic acids, their acid anhydrides and phenol derivatives. The aliphatic mono- or polycarboxylic acid having 2 to 20 carbon atoms may be saturated or unsaturated, and examples thereof include acetic acid, propionic acid, succinic acid, oleic acid, rosin acid and maleic acid. Is mentioned. Examples of the aromatic mono- or polycarboxylic acid having 7 to 20 carbon atoms include benzoic acid, p-methoxybenzoic acid,
p-chlorobenzoic acid, p-nitrobenzoic acid, cinnamic acid,
Examples thereof include phthalic acid, trimellitic acid, pyromellitic acid, and naphthoic acid. Furthermore, examples of acid anhydrides of these carboxylic acids include succinic anhydride, maleic anhydride,
Examples thereof include phthalic anhydride, trimellitic anhydride, and pyromellitic dianhydride. On the other hand, a phenol derivative is a derivative of phenol with a nuclear substitution, and has a molecular weight of 2000.
The following are preferable, and bisphenol compounds are particularly preferable. Specifically, 1,1-bis (4-hydroxyphenyl) cyclohexane, 4,4′-butylidenebis (3-methyl-6-tert-butylphenol) and the like can be preferably mentioned. In the present invention, the protonic acid may be used alone or in combination of two or more kinds. Further, the compounding amount thereof is selected in the range of 0.1 to 50 parts by weight with respect to 100 parts by weight of the rubber component. If this amount is 0.1 to 50 parts by weight, the desired effect is further exhibited, and if it is 50 parts by weight or less, other physical properties are not adversely affected. For these reasons, the preferred amount is 0.5 to 30 parts by weight, particularly 1 to 20 parts by weight. A reinforcing filler can be further used in the rubber composition of the present invention. As the reinforcing filler, those conventionally known for reinforcing rubber, such as carbon black, silica, alumina, aluminum hydroxide, calcium carbonate,
Examples thereof include titanium oxide, and these may be used alone or in combination of two or more. Of these, carbon black is particularly preferable. The carbon black is not particularly limited, and any one can be selected and used from those conventionally used as a reinforcing filler for rubber. Examples of the carbon black include FEF, SRF, HAF, ISAF,
SAF etc. are mentioned. Preferably, the iodine adsorption amount (I
Carbon black having A) of 60 mg / g or more and dibutyl phthalate oil absorption (DBP) of 80 ml / 100 g or more. By using this carbon black, the effect of improving various physical properties becomes great, but HAF, ISAF, and SAF, which are excellent in wear resistance, are particularly preferable.

The amount of the reinforcing filler compounded is preferably 20 to 120 parts by weight with respect to 100 parts by weight of the rubber component. When the compounding amount of the reinforcing filler is 20 parts by weight or more based on the rubber component, the effect of improving the reinforcing property and other physical properties is sufficiently exhibited, and when it is 120 parts by weight or less, particularly good processability is obtained. Considering the reinforcing property, other physical properties, processability, etc., the content thereof is particularly preferably in the range of 30 to 100 parts by weight.

In the rubber composition of the present invention, if desired, various chemicals usually used in the rubber industry such as a vulcanizing agent, a vulcanization accelerator, a process oil and an aging agent are used as long as the object of the present invention is not impaired. Inhibitors, antiozonants, silane coupling agents, scorch inhibitors, zinc white, stearic acid and the like can be added. Examples of the vulcanizing agent include sulfur and the like. The amount of the vulcanizing agent is preferably 0.1 to 10.0 parts by weight, more preferably 1.0 to 5 parts by weight, as the sulfur content, relative to 100 parts by weight of the rubber component. 0.0 parts by weight.
Sufficient breaking strength of vulcanized rubber if 0.1 parts by weight or more
Abrasion resistance and low heat buildup can be obtained, and sufficient rubber elasticity can be obtained by adjusting the content to 10.0 parts by weight or less.

The vulcanization accelerator which can be used in the present invention is not particularly limited, but for example, M (2-mercaptobenzothiazole), DM (dibenzothiazyl disulfide), CZ (N-cyclohexyl-2-). Benzothiazyl sulfenamide) and other thiazoles, or DP
Examples thereof include guanidine-based vulcanization accelerators such as G (diphenylguanidine), and the amount thereof is preferably 0.1 to 5.0 parts by weight, more preferably 100 parts by weight of the rubber component. It is 0.2 to 3.0 parts by weight.

The process oil that can be used in the rubber composition of the present invention is, for example, paraffin type, naphthene type,
Aromatic type etc. can be mentioned. An aromatic type is used for applications where importance is attached to tensile strength and wear resistance, and a naphthene type or paraffin type is used for applications where importance is attached to hysteresis loss and low temperature characteristics. The amount used is preferably 0 to 100 parts by weight, and 100 parts by weight or less, with respect to 100 parts by weight of the rubber component, suitable tensile strength of the vulcanized rubber,
Low heat buildup is obtained.

The rubber composition of the present invention comprises an open roll,
It is obtained by kneading using a kneading machine such as an internal mixer (closed-type kneading machine) such as a Banbury mixer, a kneader, an extruder, etc., and after the molding process, vulcanization is performed to obtain a rubber article. The rubber composition of the present invention can be used for tire treads, undertreads, carcasses, sidewalls, bead portions and other tire applications, as well as vibration isolating rubbers, belts, hoses and other industrial products. It is preferably used as rubber for tire treads.

The pneumatic tire of the present invention is produced by the usual method using the rubber composition of the present invention. That is, if necessary, the rubber composition of the present invention containing various chemicals as described above is extruded into, for example, a tread member at the unvulcanized stage, and is pasted and molded by a usual method on a tire molding machine. Then, a raw tire is molded. This raw tire is heated and pressed in a vulcanizer to obtain a tire.

In this pneumatic tire, the gas filled in the tire may be an inert gas such as air or nitrogen. The pneumatic tire using the rubber composition of the present invention for the tread is particularly excellent in grip performance.

[0025]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The Mooney scorch time of the composition and the tan δ value of the vulcanized product were measured according to the methods described below. (1) Mooney scorch time (ML _{1 + 4} ) of the composition According to JIS K6300-1994, the Mooney scorch time (ML _{1 + 4} ) at 130 ° C. was measured, and the index was displayed with the control being 100. The larger the number, the longer the Mooney scorch time and the better the productivity. (2) Tan δ of vulcanized product Using a viscoelasticity tester manufactured by Ueshima Seisakusho, a tan δ value at 50 ° C. was measured under the condition of a dynamic strain of 1%, and the control was set to 100 and displayed as an index. The higher the number,
The tan δ value is large, and the resulting tire has good grip performance.

Comparative Example 1 100 parts by weight of styrene-butadiene copolymer rubber, 80 parts by weight of aromatic oil, 80 parts by weight of SAF carbon black, 1.5 parts by weight of zinc white, 2 parts by weight of stearic acid, antioxidant. 6C [N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine]
1.5 parts by weight, paraffin wax 1.5 parts by weight, 1,
1-bis (4-hydroxyphenyl) cyclohexane 5
A masterbatch is prepared by blending 1 part by weight, and further 1.5 parts by weight of zinc white, 1.5 parts by weight of vulcanization accelerator DM (mercaptobenzothiazyl disulfide), vulcanization accelerator CZ.
A rubber composition was prepared by blending 2.5 parts by weight of (N-cyclohexyl-2-benzothiazylsulfeninamide) and 1.5 parts by weight of sulfur.

Next, this composition was vulcanized at 160 ° C. for 20 minutes to obtain a vulcanized rubber. The Mooney scorch time of the unvulcanized rubber composition and the tan δ value of the vulcanized rubber were measured and used as controls. Examples 1 to 5 and Comparative Example 2 The procedure of Comparative Example 1 was repeated, except that 5 parts by weight of an imidazole compound of the type shown in Table 1 was further added in the preparation of the masterbatch in Comparative Example 1. The results are shown in Table 1.

[0028]

[Table 1]

(Note) A: 1-benzyl-2-methylimidazole B: 1-phenylbenzimidazole C: 1-phenyl-2-methylbenzimidazole D: 1-benzyl-2-methylbenzimidazole E: 1-benzylbenzimidazole F: 1,2-dimethylbenzimidazole

Comparative Example 3 100 parts by weight of styrene-butadiene copolymer rubber, 80 parts by weight of aromatic oil, 80 parts by weight of SAF carbon black, 1.5 parts by weight of zinc white, 2 parts by weight of stearic acid, antioxidant. 6C (previously described) 1.5 parts by weight, paraffin wax 1.5 parts by weight, 1-phenylbenzimidazole 5 parts by weight to prepare a masterbatch,
Furthermore, 1.5 parts by weight of zinc white, vulcanization accelerator DM (described above)
A rubber composition was prepared by blending 1.5 parts by weight, 2.5 parts by weight of a vulcanization accelerator CZ (described above) and 1.5 parts by weight of sulfur.
Next, this composition was vulcanized at 160 ° C. for 20 minutes to obtain a vulcanized rubber. Table 2 shows the Mooney scorch time of the unvulcanized rubber composition and the tan δ value of the vulcanized product.

Examples 6 to 9 The procedure of Comparative Example 3 was repeated, except that 5 parts by weight of the protic acid of the type shown in Table 2 was further added in the preparation of the masterbatch in Comparative Example 3. The results are shown in Table 2.

[0032]

[Table 2]

(Note) G: 4,4'-butylidene bis (3-methyl-6-te)
rt-butylphenol) H: benzoic acid I: naphthoic acid J: rosin acid

[0034]

According to the present invention, a rubber component is combined with a benzimidazole derivative having a specific structure and a protic acid in a specific amount, and a specific amount of the compound is blended so that productivity is not significantly reduced and a grip region (50 ° C.) is obtained. It is possible to increase the tan δ value of the rubber composition (vulcanized product) in the vicinity. As a result, the tire using the rubber composition in the tread portion has a tan δ which increases as the tire temperature rises during running.
This has the excellent effect of suppressing drop in value and improving grip performance at high speeds.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08L 21/00 C08L 21/00 (72) Inventor Akinori Oka 463 Kagasuno, Kawauchi Town, Tokushima City, Tokushima Prefecture Otsuka Chemical Co., Ltd. Tokushima Corporation In-house (72) Inventor Ken Sonoki 463 Kagasuno, Kawauchi-cho, Tokushima City, Tokushima Prefecture Tokushima Chemical Co., Ltd.In-house (72) Inventor Shuichi Kijima 463, Kagasuno, Kawauchi-cho, Tokushima City, Tokushima Prefecture Tokushima Research Co., Ltd. In-house (72) Inventor Jun Igarashi 463 Kagasuno, Kawauchi-cho, Tokushima City, Tokushima Prefecture F-term in the Tokushima Research Institute, Otsuka Chemical Co., Ltd. (reference) 4J002 AC001 AC011 DA038 EF017 EF067 EF127 EJ017 EJ037 EU116 FD018 GN01

Claims (9)

[Claims] 1. A rubber component comprising 100 parts by weight of a natural rubber and / or a synthetic rubber, and a compound represented by the general formula (I): (In the formula, R ¹ is a hydrocarbon group having 1 to 18 carbon atoms, a heterocyclic group, an acyl group, an amide group, a sulfonyl group, a hydroxyl group or a nitro group, and R ^{2 to} R ⁶ are each independently a hydrogen atom or a halogen atom. An atom, a hydrocarbon group having 1 to 18 carbon atoms, a heterocyclic group, a hydroxyl group, an alkoxyl group, a substituted or unsubstituted amino group, an amide group, a nitro group, a substituted or unsubstituted mercapto group, a sulfonyl group or an acyl group. ) 0.1 to 50 parts by weight of a benzimidazole derivative represented by the formula (1) and 0.1 to 50 parts by weight of a protic acid are compounded. 2. The rubber composition according to claim ¹ , wherein in the general formula (I), R ¹ is a phenyl group. 3. The protonic acid is selected from aliphatic mono- or polycarboxylic acids having 2 to 20 carbon atoms, aromatic mono- or polycarboxylic acids having 7 to 20 carbon atoms, their acid anhydrides and phenol derivatives. The rubber composition according to claim 1, which is at least one of the following: 4. The rubber composition according to claim 3, wherein the phenol derivative is a bisphenol compound. 5. The bisphenol compound is 1,1-
Bis (4-hydroxyphenyl) cyclohexane or 4,4′-butylidene bis (3-methyl-6-tert-)
Butylphenol), The rubber composition according to claim 4. 6. The rubber composition according to claim 1, further comprising 20 to 120 parts by weight of a reinforcing filler. 7. The rubber composition according to claim 6, wherein the reinforcing filler is carbon black. 8. A pneumatic tire using the rubber composition according to claim 1 as a member. 9. The pneumatic tire according to claim 8, wherein the member is a tread.