JPH09227720A - Rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber composition effective for improving maneuverability of a car and reducing the fuel cost. SOLUTION: This rubber composition is used as a base part of a steel belt radial tire for a passenger car furnished with a tread having a double-layer structure composed of a road-side cap part and a belt-side base part. The composition is produced by compounding 100 pts.wt. of a diene rubber with >=40 pts.wt. of a carbon black having a nitrogen-adsorption specific area N2 SA of 35-105m<2> /g and a dibutyl terephthalate absorption DBP of 160-210 mL/100 g and has a dynamic elastic modulus (E') of >=100×10<6> dyn/cm<2> at 30 deg.C and a loss tangent (tanδ) of <0.15 at 60 deg.C.

Description

Detailed Description of the Invention TECHNICAL FIELD OF THE INVENTION

The present invention relates to a rubber composition, and more particularly to a rubber composition applied to a base portion when the tread portion has a two-layer structure.

[0002]

2. Description of the Related Art It is known that in order to reduce the rolling resistance of a tire, it is sufficient to reduce the energy loss of compounded rubber. Therefore, conventionally, techniques such as increasing the particle size of carbon black to be used and reducing the amount of carbon black compounded have been adopted.

[0003]

However, in the above method, in order to reduce the strength of rubber, it is difficult to further reduce the rolling resistance and achieve the fuel consumption higher than the current level. In addition, this method also lowers the dynamic elastic modulus of rubber, which reduces steering stability and affects the tire's dynamic performance.

Therefore, an object of the present invention is to provide a rubber composition which can reduce energy loss and rolling resistance without lowering elastic modulus and strength.

[0005]

In order to achieve the above object, the present invention has the following constitution. That is, a rubber composition applied to the base portion of a steel belt radial tire for passenger cars, which comprises a tread having a two-layer structure of a tread side cap portion and a belt side base portion, wherein 100 parts by weight of diene rubber is used. In contrast, nitrogen adsorption method specific surface area N ₂
40 parts by weight or more of carbon black having SA of 35 to 105 m ² / g and dibutyl terephthalate oil absorption DBP of 160 to 210 ml / 100 g is blended, and the dynamic elastic modulus (E ′) at 30 ° C. is 100 ×. 10 ⁶
Loss tangent (tan at 60 ° C, dyn / cm ² or more)
δ) is less than 0.15.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. As the rubber component according to the present invention, various rubbers such as natural rubber (NR), styrene-butadiene rubber (SBR) and butadiene rubber (BR) can be used alone or in a blend as long as they are diene rubbers. .

Further, the carbon black used in the present invention uses a raw material having a high aromatic content, and a reaction furnace according to an ordinary oil furnace method is used to produce reaction temperature, reaction time, combustion gas flow rate, and feed oil in the choke section. It can be manufactured by controlling the concentration and the like.

The rubber composition of the present invention requires compounding agents usually used in the rubber industry, such as a vulcanizing agent, a vulcanization accelerator, a vulcanization accelerating aid, an antiaging agent and a softening agent. It can be appropriately blended.

The operation of the present invention will be described below. If the N ₂ SA of carbon black is less than 35 m ² / g, the fracture characteristics will deteriorate, and if it exceeds 105 m ² / g, the effect of improving the low heat buildup will not be obtained, and DBP will be 160 ml / 100 g
If it is less than 210 ml, it is not possible to secure both the strength of the rubber and the reduction of rolling resistance, and if it exceeds 210 ml / 100 g, the breaking strength is lowered due to the orientation of the rubber composition. When the amount of carbon black is less than 40 parts by weight, the effect of improving the elastic modulus cannot be obtained, and in order to obtain the further effect of reducing the rolling resistance, it is preferably 65 parts by weight or less. Further, E ′ of the rubber composition of the present invention is 100 × 10 ⁶ dyn / cm.
^If it is less than ² , the effect of improving athletic performance of the tire cannot be obtained, and in order to further improve the athletic performance, 140 ×
It is preferably 10 ⁶ dyn / cm ² or more. Further, if the loss tangent (tan δ) at 60 ° C. is 0.15 or more, the rolling resistance reducing effect cannot be expected, and in order to obtain the further rolling resistance reducing effect, less than 0.11 is preferable.

[0010]

EXAMPLES The present invention will be described below based on Examples and Comparative Examples. Vulcanized rubbers and trial tires were prepared according to the formulations shown in Table 1, and the respective properties were determined by the following measurement methods. The tire size is 185 / 70R14
The composition shown in Table 1 is applied only to the base tread rubber, and the cap tread rubber is common to all the examples.
℃) 140 × 10 ⁶ dyn / cm ² , tan δ (60
C.) was 0.28, and the volume of the base rubber was 15% with respect to the entire tread. According to N ₂ SA ASTM D3037. According to DBP ASTM D2414. E ′ and tan δ had an initial strain of 10%, a frequency of 60 Hz, and a dynamic strain of 1%, and the temperature was measured at 30 ° C. and 60 ° C. using a Toyo Seiki spectrometer. Rolling resistance The rolling resistance index is lower than the value calculated from the moment of inertia at a predetermined speed by contacting the tire on a drum with an outer diameter of 1.7 m, rotating the drum, increasing the speed to a certain speed, and coasting the drum. Evaluated by the formula. Comparative Example 5 was used as a control. The smaller the value, the smaller the rolling resistance. (Moment of inertia of test tire / moment of inertia of control tire) × 100 Dynamic performance on dry road A high- performance German-made passenger car was used to run on a dry circuit, and the lap time and feeling at high speed (driving, braking performance) , Steering response, road surface grip characteristics during steering, controllability after exceeding slip limit)
Was comprehensively evaluated and evaluated as the exercise performance. Similarly, Comparative Example 5 was used as a control. The larger the value, the better the exercise performance.

[0011]

[Table 1]

As described above, in each of Examples 1 to 7, it was possible to achieve both rolling resistance and tire motion performance.

[0013]

According to the present invention, rolling resistance can be reduced, fuel consumption can be reduced, and tire dynamic performance can be improved.

Claims (1)

[Claims] 1. A rubber composition applied to the base portion of a steel belt radial tire for passenger cars, which comprises a tread having a two-layer structure of a tread side cap portion and a belt side base portion, wherein the diene rubber is used. With respect to 100 parts by weight, the nitrogen adsorption specific surface area N ₂ SA is 35 to 105 m ² / g and the dibutyl terephthalate oil absorption DBP is 160 to 210 ml / 100 g.
40 parts by weight or more of carbon black, which has a dynamic elastic modulus (E ′) at 30 ° C. of 100 ×
A rubber composition having a loss tangent (tan δ) of less than 0.15 at 10 ⁶ dyn / cm ² and 60 ° C.