JP2000038479A - Rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition capable of exhibiting a good deterioration-preventing performance even in a tire at an end period of its running by a synergistic effect of compounding a natural rubber and/or a diene- based synthetic rubber with a specific age resister in a specific ratio. SOLUTION: This rubber composition contains (A) a natural rubber and/or a diene-based synthetic rubber, and (B) a blended material of N-(1,3- dimethylbutyl)-N'-phenyl-p-phenylenediamine (hereinafter as 6C) with a 2,2,4- trimethyl-1,2-dihydroquinoline polymer (hereinafter as RD) in (20:1)-(1:1) weight ratio. Further, the content of the component (B) is preferably 1-5 pt.wt. based on 100 pts.wt. component (A). In this way, if the using ratio of 6C to RD in the component B is within the above range, a synergistic effect is exhibited to suppress the deterioration of the rubber in a tire in an end period of its running effectively and also it becomes possible to improve the adhesion of a tire cord to the rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a rubber composition,
More specifically, the present invention relates to a rubber composition having excellent deterioration prevention performance and good adhesion to a tire cord, and particularly suitable as a tire material.

[0002]

2. Description of the Related Art In recent years, the life of tires has been dramatically increased due to the development of a highway network, an increase in road pavement ratio, and progress in tire development. I have. Various techniques have been used to improve the durability of the tire, but suppressing deterioration of the rubber is one of the important techniques for improving the durability of the tire. Various factors are involved in the deterioration of rubber. For example, the deterioration progresses due to oxidation, thermal deterioration, bending cracks, sunlight cracks, ozone deterioration, copper / manganese damage, and the like. Therefore, when selecting an anti-aging agent, consider the type of the above-mentioned deterioration preventing action and consider the effect on the vulcanization rate, the effect on the physical properties of unvulcanized rubber and vulcanized rubber, coloring, contamination, and blooming properties. It is necessary to consider toxicity, toxicity, and combined effects.

As anti-aging agents, amine-based anti-aging agents are mainly used. These amine-based anti-aging agents can be classified into, for example, naphthylamine, diphenylamine, p-phenylenediamine, quinoline and other amines. it can. Typical examples of naphthylamines include phenyl-α-naphthylamine, and typical examples of diphenylamines include reaction products of diphenylamine and acetone and reaction products of diphenylamine and aniline and acetone. Products, octylated diphenylamine and the like are known. Typical examples of the p-phenylenediamine type include N-isopropyl-N′-phenyl-p-phenylenediamine (3
C), N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine (6C) and the like, and typical quinoline-based compounds include 2,2,4-trimethyl-1, 2-dihydroquinoline polymer (RD), 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline (AW) and the like. In general, the prevention of tire rubber deterioration includes prevention of oxidation, copper damage, bending cracks, and the like, as well as heat deterioration prevention. However, the above-mentioned conventional anti-aging agents can sufficiently prevent tire rubber deterioration due to these various causes. At present, it cannot be prevented. In particular, the prevention of deterioration of the tire rubber at the end of traveling when the oxygen concentration and the water content in the rubber increase is insufficient, and a solution to the problem is desired.

[0004]

Under such circumstances, the present invention is excellent in deterioration prevention performance, and exhibits good deterioration prevention performance when used as a material for a tire, especially in a tire at the end of running. It is intended to provide a rubber composition.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to develop a rubber composition having the above-mentioned preferable properties, and as a result, they have specified ratios of 6C and RD as anti-aging agents. It has been found that the rubber composition exerts a good deterioration preventing performance even in a tire at the end of running due to its synergistic effect, and also improves the adhesion to a tire cord. The present invention has been completed based on such findings. That is, the present invention provides (A) a natural rubber and / or a diene-based synthetic rubber, (B) N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine, and 2,2,4- An object of the present invention is to provide a rubber composition containing a combination of a trimethyl-1,2-dihydroquinoline polymer in a weight ratio of 20: 1 to 1: 1.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the rubber composition of the present invention,
As the component (A), a natural rubber and / or a diene-based synthetic rubber is used. Here, as the diene-based synthetic rubber,
For example, polyisoprene synthetic rubber (IR), polybutadiene rubber (BR), styrene-butadiene rubber (SB)
R), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR) and the like. The natural rubber and the diene-based synthetic rubber of the component (A) may be used alone or in combination of two or more. In the rubber composition of the present invention, as the antioxidant of the component (B), a compound represented by the formula (I):

[0007]

Embedded image

N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine (6)
C) and formula (II)

[0009]

Embedded image

2,2,4-trimethyl-1,
A mixture with a 2-dihydroquinoline polymer (RD) is used. The anti-aging agent 6C represented by the above formula (I) is known as an anti-aging agent and an ozone deterioration preventing agent for natural rubber, BR, IR, SBR and the like, and has an action of preventing oxidation, copper damage, bending cracks and the like. Is excellent. This can be produced by reductive alkylation of 4-aminodiphenylamine with methyl isobutyl ketone in the presence of hydrogen, and can be easily obtained as a commercial product.

On the other hand, RD represented by the formula (II) has an ordinary anti-aging effect on natural rubber, SBR, IR, BR, NBR, CR, EPDM, etc. and has particularly excellent heat deterioration prevention. It is known to have an effect. This is a polymer obtained by condensing aniline and acetone in the presence of a catalyst. In the present invention, a purified product (RD-S) having n of 2 to 3 is preferred.
This can be easily obtained as a commercial product.
In the present invention, as the component (B), 6C and RD
Are used in a weight ratio of 20: 1 to 1: 1. When the use ratio is within the above range, a synergistic effect is exhibited, deterioration of the rubber in the tire at the end of traveling is effectively suppressed, and the adhesion between the tire cord and the rubber is improved, and the tire durability is further improved. The performance is improved. If the use ratio is out of the above range, the synergistic effect is not sufficiently exhibited, and the object of the present invention cannot be achieved. From the viewpoint of the effect, the preferred proportion of 6C and RD is in the range of 10: 1 to 2: 1 by weight, most preferably in the range of 9: 1 to 7: 1.

The content of the component (B) in the rubber composition of the present invention, that is, the total content of 6C and RD, is defined as (A)
It is usually in the range of 1 to 5 parts by weight per 100 parts by weight of natural rubber or diene-based synthetic rubber as a component. If the content is less than 1 part by weight, the effect of preventing deterioration may not be sufficiently exerted. If the content exceeds 5 parts by weight, no improvement in the effect is recognized for the amount, and other physical properties may be impaired. Become. In addition, even if the use ratio of 6C and RD is different,
If the content of the component (B) is the same, the initial rubber properties such as elongation at break, tensile strength at break and workability hardly change. In the rubber composition of the present invention, in addition to the above components, a compounding agent usually used in the rubber industry can be appropriately compounded in a usual compounding amount. Specifically, fillers such as carbon black and silica, softeners such as aroma oil, vulcanizing agents such as sulfur, guanidines such as diphenylguanidine, thiazoles such as mercaptobenzothiazole, N, N'-dicyclohexyl- Vulcanization accelerators such as sulfenamides such as 2-benzothiazolylsulfenamide, thiurams such as tetramethylthiuram disulfide, vulcanization accelerators such as zinc oxide, stearic acid, and other antiaging agents. is there.

Among them, fillers such as carbon black and silica are used as reinforcing agents for increasing the tensile strength, breaking strength, modulus, hardness, etc. of the vulcanized rubber, and improving the abrasion resistance and tensile resistance. Zinc oxide is known as a vulcanization accelerator which forms a complex compound with a fatty acid to enhance the vulcanization acceleration effect.

[0014]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 Natural rubber (manufactured by Tech Bee Hang Co., trade name: RSS #
4) 100 parts by weight, 60 parts by weight of carbon black (N330, manufactured by Tokai Carbon Co., Ltd.), 5 parts by weight of zinc oxide, antioxidant 6C in the amount shown in Table 1 [Ouchi Shinko Chemical Co., Ltd. And trade name: Nocrack 6C] and / or RD
-S [manufactured by Seiko Co., Ltd., trade name: non-flex], vulcanization accelerator N, N'-dicyclohexyl-2-benzothiazolylsulfenamide [manufactured by Ouchi Shinko Chemical Co., Ltd., trade name: Noxeller DZ] and 1 part by weight of sulfur and 5 parts by weight of sulfur. 1 to No. Eleven types of rubber compositions were prepared.

Next, using these rubber compositions, each CR
A test (cord / rubber adhesion test) A sample was prepared and left in the air at 80 ° C. for one month, and then the adhesion between the cord and the rubber and the prevention of rubber deterioration were evaluated according to the following methods. Table 1 shows the results. (1) Adhesion between cord and rubber According to the method of ASTM-D-2229, the rubber adhesion rate (%) of the cord was determined, and the adhesion was evaluated. The higher the value, the better the adhesiveness. (2) Deterioration prevention of rubber Increase in oxygen concentration in rubber by the following method (%)
Was measured, and the deterioration prevention properties of the rubber were evaluated. A smaller value indicates better deterioration prevention. Measurement method: About 10 mg of a sample rubber composition was precisely weighed,
Using CHN-O RAPID manufactured by ERAEUS,
Nitrogen / helium mixed atmosphere (95/5) at about 1100 ° C
After the oxygen was converted into carbon monoxide by burning in a combustion catalyst and passing the combustion gas through a carbon catalyst, the oxygen concentration (O _s ) was measured by an infrared spectrometer. The regard to sample rubber composition before deterioration test, in the same manner as described above to measure the oxygen concentration (O _C), the difference of both, i.e. as an increase of (O _s -O _C) the oxygen concentration (%) evaluated.

[0016]

[Table 1]

6C: N- (1,3-dimethylbutyl)-
N'-phenyl-p-phenylenediamine, manufactured by Ouchi Shinko Chemical Co., Ltd., trade name: Nocrack 6C RD-S: purified product of 2,2,4-trimethyl-1,2-dihydroquinoline polymer, refined As is clear from Table 1, the product having a 6C / RD-S weight ratio in the range of 20/1 to 1/1 defined by the present invention is as follows.
It can be understood that the adhesiveness between the rubber and the cord and the prevention of deterioration are superior due to the synergistic effect as compared with those deviating from this range. Example 2 No. 2 obtained in Example 1 was obtained. 1, No. 3, No. 6, N
o. 9 and No. 9 Using the rubber compositions of No. 11, test tires (11R22.5) were prepared. Next, a drum test with a 150% load was performed on each tire to determine the drum travel distance. Further, for the tire after the drum test, the oxygen concentration in the rubber was measured in the same manner as in Example 1 to evaluate the deterioration prevention of the rubber, the rubber adhesion rate of the cord was obtained, and the adhesion was evaluated. . Second result
It is shown in the table.

[0018]

[Table 2]

(Note) 6C, RD-S: Same as the footnote in Table 1. As is clear from Table 1, those having a 6C / RD-S weight ratio in the range of 20/1 to 1/1 specified in the present invention are:
Compared to those deviating from this range, the synergistic effect shows that the drum traveling distance is longer, and even in the tire at the end of traveling, the rubber deterioration prevention property and the adhesion to the cord are better.

[0020]

According to the rubber composition of the present invention, by combining 6C and RD in a specific ratio as an anti-aging agent, the rubber composition exhibits excellent deterioration preventing performance due to its synergistic effect and is used for tires. In such a case, particularly at the end of running, the tire exhibits good deterioration prevention properties, improves the adhesion between the cord and the rubber, and has the effect of improving the durability of the tire.

Claims (2)

[Claims] 1. A natural rubber and / or a diene-based synthetic rubber, and (B) N- (1,3-dimethylbutyl) -N ′.
Containing a combination of -phenyl-p-phenylenediamine and a 2,2,4-trimethyl-1,2-dihydroquinoline polymer in a weight ratio of 20: 1 to 1: 1 Composition. 2. The composition according to claim 1, wherein the content of the component (B) is 10%.
The rubber composition according to claim 1, wherein the amount is 1 to 5 parts by weight per 0 parts by weight.