KR100269542B1 - Rubber composition for tire tread - Google Patents

Abstract

PURPOSE: Provided is a rubber composition which is excellent in processability and dispersibility of carbon black, and provide effects of decreasing of hysteresis due to rotation resistance and enhancing of brake power. CONSTITUTION: The rubber composition comprises 20-80 parts by weight of tin coupled, solution polymerized styrene-butadiene rubber based on 100 parts by weight of crude rubber. The styrene-butadiene rubber has a Mooney viscosity of 33-85 and glass transition temperature of -17 to -86 deg.C. The styrene-butadiene rubber contains 5-45% of styrene and 55-95% of butadiene. The butadiene consists of 13-81% of vinyl, 8-31% of cis, and 12-53% of trans. The styrene-butadiene further comprises 22-32% of aromatic oil.

Description

Tread rubber composition for tires

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tread rubber composition for tires that reduces hysteresis due to rolling resistance and improves braking force in a general passenger car tire, and more specifically, oil-based solution polymerization. By adding styrene-butadiene rubber to the compounding rubber, it has excellent processability and dispersibility of carbon black, and strong bonding of carbon black and tin reduces hysteresis by rotational resistance and improves braking force. It is about.

The performance requirements of today's tires are so diverse that there is a need for technology that properly adjusts all characteristics such as steering stability, noise, straightness, rolling resistance, braking force and wear. Among them, rolling resistance is directly related to fuel efficiency of automobiles, so reducing it is one of the most important goals. In particular, in the current situation where energy saving and green round are emerging as a global concern, research and development are actively being conducted to solve them.

Conventionally, carbon black is partially or completely replaced with modified silica to reduce the rolling resistance by forming a bond between rubber and filler, and does not affect wear and braking force. And a method of properly adjusting the vulcanization system was used. However, increasing the fuel economy by reducing rotational resistance using these methods is not very effective or has already reached the limit. To overcome this problem, a rubber modified with end groups or an alkylphenolsulfide formaldehyde oligomer is used. Development of new technologies, such as the application of vulcanization systems, is actively underway.

An object of the present invention is to use oil-based solution-polymerized styrene-butadiene rubber, especially tin (Sn) -bonded styrene-butadiene rubber, as part of the rubber component of the rubber compound, and to be excellent in processability and dispersibility of carbon black, and in the rubber compound. It is to provide a rubber composition that can improve the rotational resistance and braking force of the tire at the same time through the strong combination of tin and carbon black.

The rubber composition according to the present invention for achieving the above object is made by replacing a part of the rubber of synthetic rubber, natural rubber or a mixture thereof widely used with oil-based solution-polymerized styrene-butadiene rubber It is done.

As the compounding rubber used in the present invention, any rubber of natural rubber, synthetic rubber, or a mixture of natural rubber and synthetic rubber can be used, and the content ratio is 0 to 50 parts by weight of natural rubber and 50 to synthetic rubber. 100 parts by weight, the solution-polymerized styrene-butadiene rubber added with double oil is preferably 20 to 80 parts by weight, and the effect of reducing the rolling resistance is sufficient when the amount of the solution-polymerized styrene-butadiene rubber added with oil is less than 20 parts by weight. If it does not appear, if it exceeds 80 parts by weight, there is a fear that the braking force, wear and mechanical properties deteriorate.

The solution-polymerized styrene-butadiene rubber to which the oil is added has a pattern viscosity of 33 to 85, a glass transition temperature of -17 to 86 ° C, a styrene content of 5 to 45%, and a butadiene content of 55 to 95%, butadiene component Among them, tin-coupled rubber having a vinyl content of 13 to 81%, a sheath content of 8 to 31%, and a trans content of 12 to 53%, and an aromatic oil content of 22 to 32% is preferable. .

The present invention will be described in detail through the following examples.

Example

1) Preparation of Test Rubber

Compounding specifications of the rubber composition are shown in Table 1 below.

Table 1. Rubber Formulation Table

Comparative example Example Emulsion Polymerization Styrene-Butadiene Rubber Solution Polymerization Styrene-Butadiene Rubber ¹⁾ Carbon Black ²⁾ Process Oil Zinc Oxide Stearic Acid Antioxidant Sulfur Vulcanizer 100-80203241.92.3 505080203241.92.3

¹⁾ Solution polymerization Styrene-butadiene rubber: pattern viscosity 70, glass transition temperature -55 ℃, styrene content 22%, butadiene content 78%, butadiene vinyl content 38%, cis content 18%, trans content 44%. Tin Coupled Rubber with 27% Aromatic Oil.

²⁾ Carbon Black: N-234 Carbon Black

2) Vulcanization and property measurement

Vulcanization conditions and tests of the compounded rubber were tested according to ASTM standards, the results are shown in Table 2 below.

Table 2. Vulcanization Characteristics and Property Test Results

Comparative example Example Viscometer (125 ℃) Viscosity Scotch Time (T5), Minute Meter (160 ℃) Maximum Torque Vulcanization Time (T90), Minute Stress-Strain Test (160 ℃ * 17 minutes, Hardening) Hardness 300% Modulus (kg _f / Tensile Strength (kg _f / ㎠) Elongation (%) Flexometer Test Heating Characteristics (℃) Ablation Test Loss (mg) Leobibronn Test Tan Delta 0 ℃ 70 ℃ 4936.133.69.67011624254832.917.50.2510.186 4730.433.68.17211721749532.820.00.2650.176

* Curing condition: 160 ℃, 17 minutes curing

As shown in Table 2, in the case of replacing the synthetic rubber with a part of the oil-based solution-polymerized styrene-butadiene rubber, the rotational resistance (tan delta value at 70 ° C.) was remarkably superior to that of the comparative example. It can be seen that the braking force (tan delta value at 0 ° C.) is also improved at the same time. In addition, vulcanization properties such as wear, heat generation and tensile strength showed similar levels.

As can be seen from the above examples and comparative examples, according to the present invention, a part of rubber made of natural rubber or synthetic rubber or a mixture of natural rubber and synthetic rubber is added to 20 to 80 parts by weight of a solution-polymerized styrene-butadiene rubber to which oil is added. When used as an alternative, the processability and dispersibility of carbon black are excellent, and the strong bonding of carbon black and tin reduces hysteresis due to rotational resistance and improves braking force.

Claims (1)

Pattern viscosity is 33 ~ 85, glass transition temperature is -17 ~ -86 ℃, styrene content is 5 ~ 45%, butadiene content is 55 ~ 95%, and the vinyl content is 13 ~ 81%, cis content 8-31%, trans content 12-53%, tin-coupled solution styrene-butadiene rubber added 22-32% of aromatic oil (Aromatic oil) 20- Tread rubber composition for a tire, characterized in that it comprises 80 parts by weight.