KR100505325B1 - A rubber composition for tire tread - Google Patents

Abstract

The present invention is a rubber composition for tire tread.

The present invention relates to 50 parts by weight of styrene butadiene rubber having a styrene content of 23.5%, 20 to 30 parts by weight of styrene butadiene rubber having a styrene content of 40 to 50%, and 100 parts by weight of synthetic rubber consisting of 20 to 30 parts by weight of butadiene rubber. A rubber composition for tire treads comprising 70-80 parts by weight of carbon black having a adsorption surface area of 115 to 130 m 2 / g, 3-5 parts by weight of terpene tall oil rosin, and conventional additives.

Such a rubber composition has an effect of simultaneously improving the wear performance and the driving / braking performance, which are performances that are opposite to each other, and also complement the handling performance.

Description

Rubber composition for tire treads

Representative materials used in rubber compositions among the raw materials used in tires are carbon blacks used as rubbers and reinforcing agents.

Like rubber reinforcement, the use of rubber should be suitable for the conditions of use, and it is necessary to accurately understand the severity of the conditions of use in order to select a polymer that can perform optimally.

In particular, unlike truck bus radial tires (hereinafter referred to as TBR tires), products of more than 6 PLY and less than 10 PLY require a wear performance and various characteristics required for a tire for a passenger car (PCR TIRE).

When the tires are driven and braked, the tread rubber wears out and eventually wears out.The tires must be used up to the end of the wear and the driving / braking performance is maintained as in the beginning, regardless of dry or wet road surface. Should be.

In general, abrasion performance and driving / braking performance are opposite to each other, and it is difficult to improve both performances at the same time, and this technique requires a lot of tire knowledge.

In order to improve such contradictory performance, the amount of carbon black, which is an organic filler, is lowered and a polymer which is advantageous for abrasion performance is used. However, as the required performance is changed as the amount of filler decreases, the decrease in the amount of filling should be careful.

Until now, many efforts have been made to simultaneously improve these opposing performances, such as wear and driving / braking performance. However, there has been no clear performance. Even though the performance has been improved, only the driving / braking performance is considered. The problem of poor handling performance has emerged.

Accordingly, the present invention uses a mixture of styrene butadiene rubber having different styrene contents (hereinafter referred to as SBR), that is, a conventionally used SBR and a higher styrene content SBR, and a terpene among carbon black having a small particle size and a resin having a reinforcing effect. It aims to simultaneously improve the wear performance and driving / braking performance, which are mutually opposite performances, using complementary oil rosin, and compensate for the handling performance under low deformation.

The present invention relates to 50 parts by weight of styrene butadiene rubber having a styrene content of 23.5%, 20 to 30 parts by weight of styrene butadiene rubber having a styrene content of 40 to 50%, and 100 parts by weight of synthetic rubber consisting of 20 to 30 parts by weight of butadiene rubber. It is to provide a rubber composition for tire tread consisting of 70-80 parts by weight of carbon black, terpene-based tall oil rosin 3-5 parts by weight, and a conventional additive with an adsorption surface area of 115 to 130 m 2 / g.

Synthetic rubber used in the present invention is used by mixing styrene butadiene rubber (hereinafter referred to as SBR) and butadiene rubber (hereinafter referred to as BR) produced by copolymerizing styrene and butadiene.

The styrene content of the commonly used SBR is 23.5%, and the styrene content is 40 to 50%, and a mixture of SBR having a higher styrene content than the SBR used normally is used.

Excessive use of SBR with a high styrene content generally reduces wear performance but improves drive / braking performance. Therefore, in the range of not deteriorating the wear performance, 50 parts by weight of SBR having a styrene content of 23.5%, 20-30 parts by weight of SBR having a styrene content of 40-50%, and 20-30 parts by weight of BR, respectively. Use one synthetic rubber.

The styrene content of the SBR having a high styrene content is more preferably 40%.

The carbon black used in the present invention has an iodine adsorption surface area of 115 to 130 m 2 / g, and 70 to 80 parts by weight based on 100 parts by weight of the synthetic rubber.

Carbon black having an iodine adsorption surface area of 115 to 130 m 2 / g has a smaller particle diameter than the conventional one, and the smaller the particle diameter, the better the wear performance. This can compensate for the disadvantageous wear performance when using SBR with a high styrene content.

Terpene tall oil rosin is a resin having a reinforcing effect under the trade name MY-60 as a melt blend of tall oil resin / C9 petroleum resin / terpene resin.

The terpene-based tall oil rosin is preferably used in an amount of 3 to 5 parts by weight based on 100 parts by weight of the synthetic rubber, which improves the hardness of the rubber composition to compensate for handling performance during driving.

Common additives used in the present invention include zincation, stearic acid, N-cyclohexyl-2-benzothiazyl sulfenamide, Tetrametyl thiuram disulfide and sulfur.

Hereinafter, the present invention will be described with reference to Examples.

Examples 1 and 2

SBR having a styrene content of 23.5%, SBR having a styrene content of 40%, BR, tall oil rosin and the usual additives were mixed and vulcanized in the composition ratios shown in Table 1 below to prepare rubber specimens of Examples 1 and 2.

Comparative example

A rubber sample of Comparative Example was prepared in the same manner as in Example 1 except that SBR having 40% styrene content and tall oil rosin was not used.

TABLE 1

1) Synthetic rubber 1: SBR with 23.5% styrene content, 13% CIS content and 37.5% oil

2) Synthetic rubber 2: SBR with 40% styrene and 37.5% oil

3) Synthetic Rubber 3: BR with 98% CIS Content

4) Carbon Black 1: Carbon black with nitrogen adsorption surface area 110-120 ㎡ / g, iodine adsorption surface area 115-125 mg / g

5) Carbon black 2: Carbon black with nitrogen adsorption surface area 140-150 m 2 / g, iodine adsorption surface area 120-130 mg / g

6) Accelerator 1: N-cyclohexyl-2-benzothiazyl sulfenamide

7) Accelerator 2: Tetrametyl thiuram disulfide

Test Example

In order to measure the physical properties of the rubber specimens of Examples 1 to 2 and Comparative Examples, hardness, hysteresis, and rambon wear performance were tested as shown in Table 2 below.

Hardness

The hardness of the rubber is measured by pressing the needle attached to the tester on the specimen.

Hysteresis

It is related to the driving / braking performance of tires as a measure of energy loss. Viscoelasticity tester is used to simulate the displacement of tread rubber during tire travel, and the viscosity and elastic stress ratio obtained by measuring the energy loss of rubber by measuring the viscosity and elasticity of rubber at various temperature ranges.

If this value is increased at high temperatures, heat generation is increased, and if it is increased at low temperatures, traction, that is, driving / braking performance is improved.

Rambon wear

The rubber specimen is made into a spherical shape similar to that of a tire, and it is run by applying a constant load on the polished stone which simulates the road surface.

TABLE 2

As shown in Table 2, when the physical properties of the Examples and Comparative Examples were examined, Examples 1 to 2, which are rubber compositions of the present invention, had improved one point and two points, respectively, compared to the Comparative Examples, and the hysteresis measured at 0 ° C. 12% and 1% improvement, and Rambon wear performance was improved by 22% and 39%.

According to the present invention, SBR having high styrene content and carbon black and tall oil rosin having small particle diameters simultaneously improve wear performance and driving / braking performance, which are mutually opposite performances, and compensate for the handling performance required in passenger tires. The rubber composition for tire treads which is effective can be obtained.

Claims (1)

In the tread rubber composition for tires composed of styrene containing butadiene rubber and butadiene rubber, carbon black having an iodine adsorption surface area of 115 to 130 m 2 / g, natural resin-based rosin and ordinary additives, the synthetic rubber is 50 parts by weight of styrene butadiene rubber with a styrene content of 23.5%, 20 to 30 parts by weight of styrene butadiene rubber with a styrene content of 40 to 50% and 20 to 30 parts by weight of butadiene rubber, wherein the carbon black is 100 parts by weight of the synthetic rubber 70 to 80 parts by weight of the rosin, and the rosin is a terpene-based tall oil rosin 3 to 5 parts by weight based on 100 parts by weight of the synthetic rubber.