JPH0764955B2 - Rubber composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a rubber composition applicable to various rubber products such as tires, anti-vibration rubbers and fenders, and has particularly excellent grip performance. The present invention relates to a rubber composition suitable for a tread of a pneumatic tire having

(Prior Art) Recently, with the improvement of automobile performance, paving of roads, and development of highway network, the demand for pneumatic tires with high athletic performance has increased, and especially grip performance is an important required property. , Acceleration performance and braking performance. Therefore, the higher these characteristics are, the faster and more accurately and safely the vehicle can travel.

Conventionally, in order to obtain a high grip performance, a styrene-butadiene copolymer rubber (a rubber having a high glass transition temperature) having a high styrene content is selected as a tread rubber composition of a tire, or a process oil and a carbon black are used in a high amount. It was necessary to select a filled compounding system and increase the tan δ value of the rubber composition.

Further, as a method for improving the deterioration of grip performance with temperature rise, JP-A-59-187011 discloses a monomer such as 1,3-butadiene, styrene, or isoprene and diphenyl-2-methacryloyloxyethyl phosphate or diphenyl-. It is described that a copolymer rubber obtained by copolymerizing an acrylate or methacrylate compound containing a diphenylphosphate group such as 2-acryloyloxyethyl phosphate is used.

(Problems to be Solved by the Invention) However, in order to obtain high grip, when the styrene content of the styrene-butadiene copolymer is increased,
Although the grip performance is certainly improved, there is a problem that the tan δ value is lowered as the temperature of the rubber is increased by running the tire and the grip performance is drastically lowered. On the other hand, although the grip performance is improved by high filling of process oil or carbon black, there is a limit to the high filling, and there is a problem that the high filling of these results in a marked deterioration of the fracture characteristics and wear resistance. Further, the method of JP-A-59-187011 for improving the above-mentioned deterioration of grip performance due to temperature rise is not applicable to natural rubber, but depending on production conditions, a polymer such as styrene-butadiene copolymer rubber or polybutadiene may be used. There was a problem that the original properties of rubber should be impaired. From this point of view, the present inventors have previously found that the rubber composition containing the imidazole compound and / or the imidazoline compound in the Japanese Patent Application No. 60-163831 and the Japanese Patent Application No. 61-39088 has the above problems. He suggested that the points could be resolved. However, since these imidazole compounds and imidazoline compounds are basic, there is a problem that the rubber composition is likely to be scorched and workability is deteriorated.

(Means for Solving Problems) The inventors of the present invention have arrived at the present invention as a result of extensive studies to solve the above problems.

That is, in the configuration of the present invention, 100 parts by weight of rubber made of natural rubber and / or synthetic rubber,
Imidazole compound and / or imidazoline compound
0.1 to 50 parts by weight, selected from phenol derivative, carboxylic acid derivative, sulfonic acid derivative, sulfuric acid derivative, phosphoric acid derivative, cyanuric acid derivative, sulfinic acid derivative, nitric acid derivative, phosphorous acid derivative, dithiophosphoric acid derivative, carbonic acid derivative The present invention relates to a rubber composition containing 0.1 to 50 parts by weight of at least one protonic acid derivative.

Although the imidazole compound and the imidazoline compound used in the present invention are not limited, the following compounds are particularly preferable.

That is, the imidazole compound has the following general formula (In the formula, at least one of R ₁ , R ₂ , R ₃ , R ₄ , and R ₅ is a hydrogen atom, an alkyl group, a cyanoalkyl group, a benzyl group, an allyl group, a sulfonyl group, a carbonyl group, a silyl group, or a nitro group. a halogen atom, a mercapto group, - (CH _{2) n} -0-
(CH ₂ ) _m CN, − (CH ₂ ) _n OH, −COOC _n H _{2n + 1} or X is a halogen atom, and n and m are 1 to 20).

Further, the imidazoline compound has the following general formula (In the formula, at least one of R ₁ , R ₂ , R ₃ and R ₅ is a hydrogen atom, an alkyl group, a cyanoalkyl group, a benzyl group, an allyl group, a sulfonyl group, a carbonyl group, a silyl group, a nitro group, a halogen atom. , mercapto group, - (CH _{2) n} -0-
(CH ₂ ) _m CN, − (CH ₂ ) _n OH, −COOC _n H _{2n + 1} or and n = 1 and m = 1 to 20) are preferred.

In the present invention, the rubber component may be a natural rubber or a synthetic rubber, or a mixture of these. Examples of this synthetic rubber include synthetic polyisoprene rubber, polybutadiene rubber, styrene butadiene rubber and the like.

Next, the imidazole compound used in the present invention and /
Or an imidazoline compound is illustrated.

That is, as the (I) type imidazole compound, 2-
Methyl imidazole (2MZ), 2-undecyl imidazole (C11Z), 2-heptadecyl imidazole (C17
Z), 2-phenylimidazole (2PZ), 2-ethyl-
4-Methylimidazole (2E4MZ), 2-phenyl-4
-Methylimidazole (2P4MZ), 1-benzyl-2-
Methylimidazole (1B2MZ), 1-cyanoethyl-2
-Methylimidazole (2MZ-CN), 1-cyanoethylundecylimidazole (C11Z-CN), 1-cyanoethyl-2-phenylimidazole (2PZ-CN), 1-cyanoethyl-2ethyl-4methylimidazole (2E4MZ-C)
N), 2,4-diamino-6- {2'methylimidazolyl (1 ')} ethyl-S-triazine (2MZ-AZ1NE), 2,
4-diamino-6- {2'undecylimidazolyl (1 ')} ethyl-S-triazine (C11Z-AZINE),
2,4-Diamino-6- {2'ethyl-4-methylimidazolyl (1 ')} ethyl-S-triazine (2E4MZ-AZ1
NE), 1- (p-toluenesulfonyl) imidazole (PT
Z), 2,4,5, -tribromoimidazole (TBZ), 4 methylimidazole (4MZ), N-trimethylsilylimidazole (TSZ), 2-mercapto-1-methylimidazole (1M2MrZ), p- (imidazole-1) -Yl) phenol (4ZP), N-acetylimidazole (1AZ), urocanic acid (U-Acid), imidazole 4,5dicarboxylic acid (ZD-Acid), 1- (2,4,6-trimethylbenzenesulfonyl) imidazole , 2-methyl-5-nitro-1
-Imidazole ethanol (2M5N1EZ), 2-nitroimidazole, 4-phenyleneimidazole, 1,1'-carbonyldiimidazole, 4,5-diphenylimidazole 2,2'-dithiobis (4-tert-butyl-1-isopropylimidazole) , Ethyl-4-methyl-5imidazole carboxylate, histidine, 2-phenyl-4,5-dioxymethylimidazole (2PHZ), 2-
Phenyl-4-methyl-5-oxymethylimidazole (2P4MHZ), Imidazole rhidium derivative, 4 '-(imidazol-1-yl) acetophenone, 1-methylimidazole, 2-methylimidazole, 4-methylimidazole, 1,1'-thiocarbonyldiimidazole, 1- (2,
4,6-Triisopropylbenzenesulfonyl) imidazole, 2,4,5-triphenylimidazole, 1-vinylimidazole, N-ω-acetylhistamine, N-α
-Acetyl-L-histidine monohydrate, L-carnazine, N-trans-cinnamoylimidazole, 2,
4-dimethylimidazole, 1,2-dimethylimidazole, 4,5-diphenyl-2-imidazolthiol, 2
-Ethylimidazole, 2-ethyl-4-methylimidazole, N, N'-bis [3- (4,5-dihydro-1H-imidazol-2-yl) -phenyl] ureadipropanoate, 2,2'- Bis (4,5-dimethylimidazole), 1
-Benzylimidazole, etc.

Next, as the above-mentioned (II) type imidazole compound, 1-
Cyanoethyl-2-methylimidazole-trimellitate (2MZ-CNS), 1-cyanoethyl-2-phenylimidazole-trimellitate (2PZ-CNS), 1-cyanoethyl-2 undecylimidazole-trimellitate (C1
1Z-CNS), 1-cyano-2ethyl-4-methylimidazole-trimellitate (2E4MZ-CNS), 1,2-diundecylimidazole (2C11Z), 1-stearyl-2-
Undecyl imidazole (C18C11Z) etc. are mentioned.

Further, as the (III) type imidazole compound,
1-dodecyl-2-methyl-3benzylimidazolium chloride (SFZ), 1,3 dibenzyl-2-methylimidazolium chloride (FFZ), 4- (hydroxymethyl) imidazole hydrochloride, 4-imidazole acetic acid Hydrochloride, Propyl-dl-1- (1-phenylethyl) imidazole-5
-Examples include carboxylate and hydrochloride.

Examples of the imidazoline compound include 2-methylimidazoline (2MZL) and 2-phenylimidazoline (2PZ
L), 2-methylthio-2-imidazoline hydrochloride, 2- (1-naphthylmethyl) -2-imidazoline hydrochloride, trazoline hydrochloride and the like. These compounds may be used alone or in combination of two or more.

In the present invention, the compounding amount of these compounds is defined as 0.1 to 50 parts by weight with respect to 100 parts by weight of the rubber component.If the compounding amount is less than 0.1 parts by weight, the desired effect intended by the present invention can be obtained. Can not.

On the other hand, if it exceeds 50 parts by weight, not only the effect commensurate with the increase in the amount is not obtained, but also various physical properties after vulcanization are adversely affected, resulting in an unfavorable result.

As the proton acid derivative used in the present invention, a phenol derivative, a carboxylic acid derivative, a sulfonic acid derivative, a sulfuric acid derivative, a phosphoric acid derivative, a cyanuric acid derivative, a sulfinic acid derivative, a nitric acid derivative, a phosphorous acid derivative, a dithiophosphoric acid derivative, Carbonic acid derivatives, specifically 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis-4-methyl-6-tert-butylphenol, 2,5-di-tert-butylhydroquinone , 4,4'-thiobis-3-methyl-6-tert-butylphenol, styrenated-p-cresol, 4,4'-butylidene bis-
3-methyl-6-tert-butylphenol, acetic acid, succinic acid, stearic acid, oleic acid, rosin acid, maleic acid, benzoic acid, p-methoxybenzoic acid, p-chlorobenzoic acid, p-nitrobenzoic acid, cinnamic acid , Α-naphthylcarboxylic acid, phthalic acid, trimellitic acid, pyromellitic acid,
Phthalic anhydride benzenesulfonic acid, benzenesulfonic acid substituted with an alkyl group having 1 to 12 carbon atoms, α-naphthalenesulfonic acid, sulfuric acid, sulfuric acid monomethyl ester, phosphoric acid, phosphoric acid mono (2-ethylhexyl) ester, phosphoric acid Di (2-ethylhexyl) ester, cyanuric acid,
Cyanuric acid diamide, benzenesulfinic acid, p-toluenesulfinic acid, phosphorous acid, dimethyl phosphite, diphenyl phosphite, 0,0'-dimethyldithiophosphoric acid, 0,0'-bis (2-ethylhexyl) Examples thereof include dithiophosphoric acid, carbonic acid and ammonium hydrogen carbonate.

These protic acid derivatives may be used alone or in combination of two or more kinds, and may be premixed with an imidazole or imidazoline compound when compounded in a rubber, or each may be separately compounded separately. I don't care.

In addition, in the present invention, in addition to the above-mentioned imidazole compound and / or imidazole compound, a protonic acid derivative, a compounding agent usually used in the rubber industry, such as a filler, a softening agent, an antioxidant, a vulcanization accelerator. The vulcanization accelerating aid, vulcanizing agent and the like can be blended within the range of the usual blending amount as required.

(Operation) Imidazole compound and / or used in the present invention
Alternatively, when the imidazoline compound is used in combination with a protonic acid derivative, the scorch property, which was a drawback when the imidazole compound or the imidazoline compound is blended, is improved, and a tan δ value at high temperature can obtain a rubber composition that is synergistically improved. it can.

(Example) Next, the present invention will be described with reference to Examples and Comparative Examples.

Examples 1-22, Comparative Examples 1-2 With respect to 100 parts by weight of styrene-butadiene rubber, 37.5 parts by weight of aromatic oil, 65 parts by weight of ISAF carbon black, 3 parts by weight of zinc white, 0.5 part by weight of 1,3-diphenylguanidine, To 1.5 parts by weight of dibenzothiazyl disulfide and 1.5 parts by weight of sulfur, 1-stearyl-2-undecylimidazole (C
₁₈ C ₁₁ Z) or 1-benzyl-2-methylimidazole (1B2MZ) and various protic acid derivatives shown in Table 1
An unvulcanized rubber composition was obtained by mixing in an amount of 0.01 mol and kneading. For these rubber compositions, 1 according to JIS K 6300
The Mooney scorch time t ₅ at 30 ° C. was measured. The results are shown in Table 1. Also, the measurement was carried out when imidazole and a protonic acid derivative were mixed in advance, and when Comparative Example 1 and 2 did not contain a protonic acid derivative,
The results are shown in Table 1.

As is clear from Table 1, the use of protic acid
It is clear that the scorch time, which is a disadvantage of incorporating imidazole, is improved.

Next, the unvulcanized rubber compositions of Examples 1, 3, 5, 7, 9, 9, 10, 13 and 14 were vulcanized. For each of the obtained vulcanizates, using a rheometrics viscoelasticity tester, under the condition of a dynamic strain of 1%,
The tan δ at 80 ° C. was measured, and the unvulcanized rubber composition of Comparative Example 1 was similarly vulcanized to determine the increase in the tan δ value measured. The results are shown in Table 2. In addition, for comparison, a case where neither imidazole nor a proton acid derivative was blended was similarly evaluated and shown in Table 2.

As is clear from Table 2, the combined use of imidazole and a proton acid derivative synergistically improves the tan δ value at high temperatures.

(Effects of the Invention) As described above, the rubber composition of the present invention contains the imidazole compound and the imidazoline compound by mixing the rubber component with the specific imidazole compound and / or the imidazoline compound and the specific protonic acid derivative in the specific amount. The scorch property, which was a drawback in the case of blending with, was improved, and the tan δ value in the high temperature region was increased synergistically.
Therefore, when such a rubber composition is used for a tread of a tire, the tire temperature is increased due to running.
It is possible to obtain an excellent effect that the decrease in tan δ value is suppressed and the grip performance at high speed traveling is improved.

Claims (13)

[Claims] 1. An imidazole compound and / or 100 parts by weight of a rubber composed of natural rubber and / or synthetic rubber.
Or 0.1 to 50 parts by weight of imidazoline compound, phenol derivative, carboxylic acid derivative, sulfonic acid derivative, sulfuric acid derivative, phosphoric acid derivative, cyanuric acid derivative, sulfinic acid derivative, nitric acid derivative, phosphorous acid derivative, dithiophosphoric acid derivative, carbonic acid derivative A rubber composition comprising 0.1 to 50 parts by weight of at least one protonic acid derivative selected from the above. 2. An imidazole compound having the following general formula (In the formula, at least one of R ₁ , R ₂ , R ₃ , R ₄ , and R ₅ is a hydrogen atom, an alkyl group, a cyanoalkyl group, a benzyl group, an allyl group, a sulfonyl group, a carbonyl group, a silyl group, or a nitro group. a halogen atom, a mercapto group, - (CH _{2) n} -0-
(CH ₂ ) _m CN, − (CH ₂ ) _n OH, −COOC _n H _{2n + 1} or X represents a halogen atom, n and m = 1 to 20) The rubber composition according to claim 1, which is selected from at least one compound represented by the formula: 3. An imidazoline compound represented by the following general formula: (In the formula, at least one of R ₁ , R ₂ , R ₃ and R ₅ is a hydrogen atom, an alkyl group, a cyanoalkyl group, a benzyl group, an allyl group, a sulfonyl group, a carbonyl group, a silyl group, a nitro group, a halogen atom. , mercapto group, - (CH _{2) n} -0-
(CH ₂ ) _m CN, − (CH ₂ ) _n OH, −COOC _n H _{2n + 1} or The rubber composition according to claim 1, wherein n and m represent 1 to 20). 4. The phenol derivative is 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis-4'-methyl-6-tert-butylphenol, 2,5-di-tert-.
Butylhydroquinone, 4,4'-thiobis-3-methyl-6-tert-butylphenol, styrenated-p-cresol, 4,4'-butylidenebis-3-methyl-6-ter
The rubber composition according to claim 1, which is t-butylphenol. 5. The carboxylic acid derivative is acetic acid, succinic acid, stearic acid, oleic acid, rosin acid, maleic acid, benzoic acid, p-methoxybenzoic acid, p-chlorobenzoic acid, p-
The rubber composition according to claim 1, which is nitrobenzoic acid, cinnamic acid, α-naphthylcarboxylic acid, phthalic acid, trimellitic acid, pyromellitic acid, or phthalic anhydride. 6. The sulfonic acid derivative is benzenesulfonic acid,
The rubber composition according to claim 1, which is benzenesulfonic acid or α-naphthalenesulfonic acid substituted with an alkyl group having 1 to 12 carbon atoms. 7. The rubber composition according to claim 1, wherein the sulfuric acid derivative is sulfuric acid or sulfuric acid monomethyl ester. 8. The phosphoric acid derivative is phosphoric acid or phosphoric acid mono (2-
The rubber composition according to claim 1, which is an ethylhexyl) ester or a di (2-ethylhexyl) phosphoric acid ester. 9. The rubber composition according to claim 1, wherein the cyanuric acid derivative is cyanuric acid or cyanuric acid diamide. 10. The rubber composition according to claim 1, wherein the sulfinic acid derivative is benzenesulfinic acid or p-toluenesulfinic acid. 11. The rubber composition according to claim 1, wherein the phosphorous acid derivative is phosphorous acid, phosphorous acid dimethyl ester or phosphorous acid diphenyl ester. 12. The rubber composition according to claim 1, wherein the dithiophosphoric acid derivative is 0,0'-dimethyldithiophosphoric acid or 0,0'-bis (2-ethylhexyl) dithiophosphoric acid. 13. The rubber composition according to claim 1, wherein the carbonic acid derivative is carbonic acid or ammonium hydrogencarbonate.