KR100512132B1 - Silica-filled tire tread rubber composition - Google Patents

Abstract

The present invention relates to a tread rubber composition for tires reinforced with silica, and more particularly, by using solution-polymerized styrene butadiene rubber and butadiene rubber as raw material rubbers, and by adding 20 to 80 phr of highly dispersible silica prepared to facilitate dispersion. A tread rubber composition for tires with improved wear and rolling resistance properties.

Description

Silica-filled tire tread rubber composition

The present invention relates to a tread rubber composition for tires reinforced with silica, and more particularly, by adding high dispersible silica (HDS) to a synthetic rubber composed of solution-polymerized styrene butadiene rubber and butadiene rubber, And a tread rubber composition for a tire having improved rolling resistance characteristics.

Conventionally prepared tread rubber compositions for tires use only natural rubber, solution-polymerized styrene butadiene rubber or butadiene rubber as main components, and carbon black as a reinforcing agent to satisfy a certain degree of braking performance and fuel efficiency.

Tires consist of many parts and parts, but treads, especially those that contact the ground, have the most important influence on the fuel efficiency of the tires. In general, the braking performance and fuel efficiency of tires are highly correlated with the viscoelastic properties of rubber properties. Among the viscoelastic properties, the dynamic loss factor at 0 ° C is the braking performance on wet road surface, and the dynamic loss factor at 60 ° C. It has a close relationship with the rolling resistance, that is, fuel efficiency. Therefore, the higher the dynamic loss factor at 0 ° C., the better the braking performance. The lower the dynamic loss factor at 60 ° C., the better the fuel efficiency.

In order to improve fuel efficiency, friction between the tire and the road surface should be reduced. In this case, since the contrary characteristics of the braking performance of the tire are deteriorated, silica compounding has been researched and developed as a method of satisfying the contradictory characteristics simultaneously.

However, silica has high acidity due to excessive concentration of functional groups on the surface, high reactivity between filler and filler, and low reactivity with accelerator-rubber. Therefore, special processing conditions are required to obtain ideal vulcanizability. It was. In addition, a large amount of coupling agent was required.

In addition, when silica is used as a reinforcing agent in the rubber composition, the amount of silica in the rubber composition increases, which is difficult to disperse when blending with the polymer due to the silica's own specific gravity. The reinforcement tends to be somewhat inferior, such as deterioration of rubber properties due to the use of a dispersing aid and process oil.

As a dispersing aid, a compound mainly composed of metal fatty acid salts is used, which is an amphiphilic substance having both hydrophilic groups by metal ions and hydrophobic groups by fatty acids. Metal ions react with silanol groups on the silica surface to reduce the surface energy between molecules for silica aggregates that are strongly bonded to each other by hydrogen or dipole bonds, leading to decomposition during the mixing process. This is excellent and serves to dilute the rubber chains. In addition, the process oil is a hydrophobic substance composed of hydrocarbons and serves to lower the viscosity of the rubber composition by diluting rubber chains.

As such, as the amount of silica in the rubber increases, the reinforcement may be somewhat deteriorated, such as an increase in viscosity and a decrease in rubber properties due to poor dispersion.

The present invention is to improve the above problems, an object of the present invention is to improve the wear resistance and rotation resistance characteristics by adding a highly dispersible silica prepared to facilitate dispersion, braking performance and fuel economy on wet road surface It is to provide a tread rubber composition for a tire that simultaneously improves performance.

The present invention relates to a tread rubber composition for tires, wherein 20 to 80 phr of highly dispersible silica is added to 100 phr of synthetic rubber composed of solution-polymerized styrene butadiene rubber and butadiene rubber.

Highly dispersible silica (HDS) used in the present invention compared to the conventional silica, BET, DBP, CTAB, etc., the basic properties of the silica is improved dispersibility even if it is within the same range, but was developed and marketed in the silica manufacturing industry, It is not yet applied to the tire field. In the present invention, as a highly dispersible silica, a commercially available product can be purchased and used, and the content thereof is preferably 20 to 80 phr in consideration of physical properties and dispersibility. The highly dispersible silica preferably has a BET of 150 to 180 m 2 / g, a CTAB of 160 to 170 m 2 / g, and a DBP of 160 to 240 ml / 100 g.

In the rubber composition of the present invention, additives for conventional rubber compositions, for example, additives such as zinc, stearic acid, anti-aging agent, wax, aromatic oil, sulfur, accelerator, etc. may be appropriately selected and added. It is known in the art.

Hereinafter, the present invention will be described in more detail with reference to the following Examples and Comparative Examples. The following examples are merely examples for illustrating the present invention and do not limit the protection scope of the present invention.

Examples and Comparative Examples

The chemical properties of the silica used in the following Examples and Comparative Examples are shown in Table 1, and the composition ratios of the rubber compositions of Examples and Comparative Examples are shown in Table 2.

Example 1

Oil-Based Solution Polymerized Styrene Butadiene Rubber (Oil extended S-SBR) 96phr, Butadiene Rubber (BR) 30phr, Highly Dispersible Silica B 80phr, Zinc 3.0phr, Stearic Acid 2.0phr, Antioxidant 1.5phr, Wax 1.0phr, Aromatic Oil 10 phr, sulfur 1.5 phr, accelerator 3.5 phr and coupling agent 12.8 phr were placed in a Banbury mixer, mixed and released at 180 ° C.

Example 2

Except having made 80 phr highly disperse silica C instead of highly disperse silica B, it mixed in the same manner as Example 1, and discharged at 160 degreeC.

Comparative Example 1

Except having made 80 phr of normal silica A instead of highly dispersible silica B, it mixed similarly to Example 1, and discharged at 180 degreeC.

Table 3 shows the results of physical properties measured after preparing and vulcanizing the specimens from the rubber compositions prepared in Examples and Comparative Examples.

As can be seen from the above, the rubber composition according to the present invention can be easily dispersed by using highly dispersible silica (HDS) prepared to disperse the particle or aggregate structure more easily when a shear force is applied from the outside. Not only the wear characteristics but also the viscoelastic properties improve both the 0 ° C and 60 ° C dynamic loss coefficients, thereby improving both braking performance and fuel efficiency on wet roads.

1 is a silica dispersion state measured by an optical microscope for silica used in Examples and Comparative Examples,

2 is a surface roughness of the silica measured using a surface analyzer for the silica used in Examples and Comparative Examples,

3 shows particle size distribution of silica used in Examples and Comparative Examples.

Claims (1)

For 100 phr of synthetic rubber composed of solution-polymerized styrene butadiene rubber and butadiene rubber, 20 to 20 highly dispersed silica having BET of 150 to 180 m 2 / g, CTAB of 160 to 170 m 2 / g and DBP of 160 to 240 ml / 100 g. Tread rubber composition for tires, comprising 80 phr.