JPH0782421A - Rubber composition for tire having improved grip - Google Patents

Abstract

PURPOSE:To provide a rubber composition for tire capable of remarkably improving the gripping performance of a tire without lowering the high-elongation modulus, steering stability, abrasion resistance, etc. CONSTITUTION:This rubber composition for tire is produced by compounding 100 pts.wt. of a diene rubber with 5-15 pts.wt. of an imidazole compound and 60-200 pts.wt. of carbon black having a CTAB of >=160m<2>/g, 24M4DBP oil absorption of >=100mL/100g and a TINT of >=120%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition for tires, more specifically, without causing a decrease in modulus at high elongation, a decrease in steering stability and a decrease in wear resistance.
TECHNICAL FIELD The present invention relates to a rubber composition for a tire, which gives a tire having markedly improved grip (road surface grasping) performance.

[0002]

2. Description of the Related Art In recent years, in response to the demand for higher performance of automobiles, the development of high-speed tires having excellent steering stability, particularly the development of tires having excellent grip performance, has been strongly desired. Tan δ at 60 ℃ to improve tire grip performance
It is known that a high tread rubber composition may be used.

Tan of rubber composition for tread at 60 ° C.
Conventionally, in order to increase δ, (1) glass transition point (Tg)
High polymer, for example, high styrene SBR (styrene-butadiene copolymer rubber) with a large amount of bound styrene or high vinyl SBR with a large amount of vinyl bond is used as a rubber component, and (2) a large amount of carbon black is blended. Measures such as doing have been taken.

However, in the case of (1), there is a problem that the temperature dependency of the hardness of the rubber composition becomes high, the hardness is lowered at high temperature, the rigidity is lowered, and the grip performance is rather lowered. Further, in the case of (2), the dispersion of carbon black in the rubber composition is deteriorated, or the hysteresis loss of the rubber composition is increased to increase the dynamic properties of the rubber composition, particularly the heat buildup property, thereby increasing the rubber composition. There were some drawbacks such as easy deterioration of things.

Further, it has been proposed to improve the grip performance by increasing the tan δ at high temperature by blending a diene rubber with an imidazole compound (Japanese Patent Laid-Open Publication No. Sho 6-62).
See JP-A-3-130647). However, when the imidazole compound is blended, there is a problem that the modulus (300% modulus) at the time of high elongation is largely reduced in the ordinary blending, and the steering stability and the wear resistance are rather degraded.

[0006]

Accordingly, the present invention eliminates the above-mentioned problems of the prior art, and reduces the modulus at high elongation, the steering stability, and the wear resistance of the tire. To provide a rubber composition for a tire, which can remarkably improve the grip performance.

According to the present invention, 0.5 to 20 parts by weight of an imidazole compound, 160 m ² / g or more of CTAB, 100 ml / 100 g or more of 24M4DBP oil absorption and 120% or more of TINT are added to 100 parts by weight of a diene rubber. Provided is a rubber composition for a tire, which comprises 60 to 200 parts by weight.

The structure of the present invention will be described in more detail below. As the diene rubber used in the present invention, any diene rubber conventionally used for compounding tires, such as natural rubber, various styrene-butadiene copolymer rubbers (SBR), polybutadiene, polyisoprene, ethylene propylene is used. Copolymer rubber, butyl rubber and the like can be used alone or in a blend, and a blend with another rubber containing 50% by weight or more of these diene rubbers can also be used.

As described above, the carbon black blended in the rubber composition of the present invention is CTAB (surface area m ² / g per unit weight of carbon black calculated from the amount of adsorption of cetyltrimethylammonium bromide) (ASTM D3).
Measured according to the method of 765-80) 160 m ² / g or more, preferably 160 to 220 m ² / g, 24M4DBP
(Dibutyl phthalate) (measured according to the method of ASTM D3493) 100 ml / 100 g or more, preferably 1
05-145ml / 100g, TINT (JISK622
1-82, Testing method of carbon black for rubber 6.1.
In accordance with item 3, IRB # 3 is measured as a reference sample) 120
%, Preferably 120 to 150%, and in the present invention, 60 to 200 parts by weight, preferably 80 to 180 parts by weight of such carbon black is blended with 100 parts by weight of the polymer content.

When the amount of the carbon compounded is less than 60 parts by weight, tan δ at 60 ° C. becomes low, which is not preferable.
If it exceeds 100 parts by weight, the kneading property of carbon is deteriorated and abrasion resistance and strength are deteriorated, which is not preferable.

Examples of the imidazole compound blended in the rubber composition of the present invention include 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4methylimidazole, 1-cyanoethyl-2-phenylimidazole and 2 -Mercaptobenzimidazole, 2-mercaptomethylbenzimidazole and the like can be mentioned, but the imidazole compound used in the present invention is
In short, any compound containing an imidazole ring in the compound, particularly an imidazole compound in which the ring is substituted with an alkyl group, an aryl group, a cyanoalkyl group, a benzyl group or the like is included.

As described above, the amount of the imidazole compound compounded in the rubber composition of the present invention is 5 to 15 parts by weight, preferably 10 to 15 parts by weight, per 100 parts by weight of the diene rubber. If the compounding amount of the imidazole compound is less than 5 parts by weight, tan δ at high temperature does not increase and the desired effect cannot be obtained, which is not preferable. On the contrary, if it exceeds 15 parts by weight, the vulcanization rate in the vulcanization step becomes too fast. And there is a problem in workability, and the modulus at the time of high extension decreases, which is not preferable in terms of steering stability.

The tire rubber composition of the present invention contains, in addition to the above-mentioned diene rubber, imidazole compound and carbon black, sulfur, vulcanization accelerator, antioxidant, filler, softening agent, plasticizer and the like for tires. Various additives generally blended with can be blended, and such blend can be vulcanized by a common method to produce a tire tread. The compounding amount of these additives may be a general amount.

[0014]

The present invention will be described in more detail below with reference to Examples and Comparative Examples, but it goes without saying that the technical scope of the present invention is not limited to these Examples. Examples and Comparative Examples Each component was blended according to the blending content (parts by weight) shown in Table 1, and a vulcanization accelerator and a raw rubber excluding sulfur and a blending agent were prepared as follows.
After mixing for 5 minutes with a 7 liter Banbury mixer,
A vulcanization accelerator and sulfur were kneaded with this mixture for 4 minutes with an 8-inch test kneading roll machine to obtain a rubber composition. These rubber compositions were press-vulcanized at 160 ° C. for 25 minutes,
Target test pieces were prepared, various tests were performed, and the physical properties were measured. The physical properties of the obtained vulcanized product are as shown in Table 1 and FIG. The vulcanized physical properties were measured by the following methods.

1) 300% modulus Measured according to JIS K6301

2) HS (60 ° C.) The sample was left for 30 minutes or longer in a constant temperature bath adjusted to 60 ° C., and after confirming that the sample reached 60 ° C., JIS
Measured according to K6301 A-type spring hardness test method

3) tan δ (60 ° C.) Using a viscoelasticity spectrometer manufactured by Iwamoto Seisakusho, measured at a temperature of 60 ° C. under a condition of a strain rate of 10 ± 2% by extension deformation and a frequency of 20 Hz. Note that the larger the tan δ value at 60 ° C., the better the grip performance on a dry road surface when used in a tire.

[0018]

[Table 1]

[0019]

As shown in the examples, according to the present invention, a diene synthetic rubber is blended with an imidazole compound, and CTAB as carbon black is 160 m ²
/ G or more, 24M4DBP oil absorption is 100ml / 100g
As described above, by using the one having TINT of 120% or more, tan δ can be remarkably increased while maintaining the modulus at the time of high elongation, and the grip performance is maintained while maintaining the steering stability and the wear resistance at desired levels. Can be improved.

[Brief description of drawings]

FIG. 1 is a drawing showing the relationship between tan δ and 300% modulus of vulcanized physical properties in Examples and Comparative Examples of the present invention, in which the numbers indicate the numbers of Examples or Comparative Examples, and the area A is preferable. Indicates the range.

Claims (1)

[Claims] 1. An imidazole compound in an amount of 5 to 15 parts by weight and CTAB 160 relative to 100 parts by weight of a diene rubber.
m ² / g or more, 24M4DBP oil absorption 100ml / 100g
Or more and TINT 120% or more of carbon black 6
A rubber composition for a tire, which comprises 0 to 200 parts by weight.