KR100703850B1 - Rubber composition for tire tread - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition for tire treads, and more particularly, carbon black and silica are added to a raw material rubber made of a mixture of high cis-1,4 butadiene rubber, butadiene rubber having a high vinyl content, and butyl rubber. Therefore, the present invention relates to a rubber tread rubber composition having improved abrasion performance and braking performance.

Pneumatic Tire, Tread Rubber Composition

Description

Rubber composition for tire treads {RUBBER COMPOSITION FOR TIRE TREAD}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition for tire treads, and more particularly, carbon black and silica are added to a raw material rubber made of a mixture of high cis-1,4 butadiene rubber, butadiene rubber having a high vinyl content, and butyl rubber. Therefore, the present invention relates to a rubber tread rubber composition having improved abrasion performance and braking performance.

The performance required for PCR tires varies widely. For example, low rotational resistance, which is closely related to wet traction and low fuel efficiency, and noise, abrasion resistance, and braking performance. However, these performances are mutually exclusive, and it is very difficult to improve the specific performance desired without sacrificing other performance, and even more difficult to improve these performances simultaneously.

In general, silica mixed silica compounds are superior to rubbers mixed with carbon black in wet traction (wetting on wet road surfaces) and fuel efficiency (reduction of hysteresis loss at high temperatures). However, as is well known, the blind spot of the silica compound is that the wear performance is lowered compared to the compound containing carbon black.

Therefore, in order to compensate for the problem of deterioration of abrasion performance in spite of excellent performances such as wetting friction and fuel efficiency of silica compounds, a coupling system has been used to improve the interaction between the polymer and silica. In addition, many grades of carbon black have been used to improve the wear performance and fuel efficiency by changing the structure of the carbon black used together with silica.

For example, U. S. Patent No. 5,587, 417 describes a method of improving the wear and fuel efficiency performance by modifying the grade of carbon black in a polymer in which butadiene rubber is mixed with natural rubber or natural rubber. In addition, U.S. Patent Nos. 5,294,663, 5,162,409, 5,219,944, and 6,429,245 have attempted to improve wear, fuel efficiency and braking performance by modifying the polymer system while employing carbon black and silica as major reinforcing systems. However, these attempts, namely reinforcing agents (carbon black, silica) and coupling agents, have been used only in certain polymer systems, and there have been limitations in their use by the use of certain reinforcing systems when the polymer system has been altered and evaluated. On the other hand, the rubber composition used for tires, especially for passenger and light truck tires, due to the nature of its use could not increase the amount of natural rubber in order to improve fuel efficiency and wear performance. This is because the use speed of the vehicle is high and the frequency of use in the road is high, so the braking performance as well as the braking performance should be considered first.

Therefore, the amount of synthetic rubber having good braking performance must be largely increased, and therefore, there is a concern that a reduction in fuel efficiency performance is achieved among various performances.

It is an object of the present invention to provide a rubber composition for tire treads that improves the above problems and maintains wear performance and braking performance without deteriorating fuel efficiency.

Rubber composition for tire tread of the present invention is a raw rubber 100 comprising 40 to 50% by weight of high cis-1,4 butadiene rubber, 40 to 50% by weight of butadiene rubber having a high vinyl content, 10 to 20% by weight of butyl rubber It is characterized by comprising 30 to 40 parts by weight of carbon black and 10 to 20 parts by weight of silica as a reinforcing agent with respect to parts by weight.

High cis-1,4 butadiene rubber used in the present invention is a polybutadiene rubber having a sheath content of 70 to 90% by weight and a vinyl content of 2 to 10% by weight, and has high wear performance and resilience. The content of the high cis-1,4 butadiene rubber is preferably 40 to 50% by weight based on the total weight of the raw rubber, but when the content is less than 40% by weight, the rebound elasticity is lowered. There is a problem that is greatly reduced.

Butadiene rubber having a high vinyl content used in the present invention is a rubber having a vinyl content of 80% or more and a glass transition temperature of -15 ~ -20 ℃, the content is 40 to 50% by weight relative to the total weight of the raw rubber It is preferable. If the vinyl content of the butadiene rubber having a high vinyl content is less than 80%, there is a problem that the glass transition temperature of the rubber is lowered, and when the glass transition temperature is less than -20 ° C, the braking performance is disadvantageous, and -15 ° C If exceeded, wear performance is reduced. When the content of the butadiene rubber having a high vinyl content is less than 40% by weight, the effect of improving fuel efficiency is low as the vinyl content is lowered, and when the content is more than 50% by weight, wear performance decreases.

The butyl rubber used in the present invention is preferably used in an amount of 10 to 20% by weight based on the total weight of the raw material rubber. When the content is less than 10% by weight, it is disadvantageous in terms of processability, and when it is more than 20% by weight, the butyl rubber is used in high temperature vulcanization. It has an adverse effect on the deterioration of physical properties and braking performance due to the decomposition of polymer.

As the reinforcing filler used in the present invention, carbon black and silica are preferable.

The carbon black used in the present invention is preferably used 30 to 40 parts by weight based on 100 parts by weight of the raw rubber, when the content is less than 30 parts by weight, the tensile strength of the rubber can be reduced to exhibit the proper function, 40 When it exceeds the weight part, excessive physical property increase of rubber becomes very disadvantageous in fairness and fuel efficiency.

The carbon black has an iodine adsorption amount of 130 to 140 mg / g, a dibutyl phthalate (DBP) oil absorption amount of 135 to 145 cm 3/100 g, and an aggregate size distribution (ΔD50) of 58 to 65, and is a general ISAF grade. Compared with carbon black, it is desirable to increase the reinforcement while lowering the heat generation performance.

If the iodine adsorption amount of the carbon black is less than 130mg / g, the reinforcing effect is lowered, and if it exceeds 140mg / g, the exothermic increase adversely affects fuel efficiency performance.

In addition, when the DBP oil absorption amount is less than 135 cm 3/100 g, the reinforcing effect is lowered.

And, if the coagulation size distribution is less than 58, it is disadvantageous to heat generation suppression, and if it exceeds 65, the heat generation becomes too low or the reinforcing effect is lowered.

The silica used in the present invention is hydrated silica, and it is preferable to use 10 to 20 parts by weight based on 100 parts by weight of the raw rubber. If the amount is less than 10 parts by weight, it does not exert a substantial effect on fuel efficiency. If the amount is more than 20 parts by weight, the wear performance is adversely affected.

It is preferable that iodine adsorption amount of the said silica is 160-180 mg / g, and DBP oil absorption amount is 230-240 cm <3> / 100g. When the adsorption amount of iodine is less than 160 mg / g, the tensile property of the rubber is sharply reduced, the braking performance and wear performance is reduced at the same time, if it exceeds 180 mg / g, the tensile property of the rubber is too high in the processability Very disadvantageous. In addition, when the DBP oil absorption is less than 230 cm 3/100 g, the tensile property of the rubber drops sharply, and wear performance decreases. When the DBP oil absorption exceeds 240 cm 3/100 g, the tensile property of the rubber is too high, which is very disadvantageous in processability.

In addition, the rubber composition for tire treads of the present invention may further include a silica coupling agent and caster oil. The amount of the silica coupling agent may vary depending on the amount of the silica, and 4 parts by weight or less, preferably 2 to 4 parts by weight, based on 100 parts by weight of the raw rubber.

The caster oil used in the present invention preferably uses organic unsaturated fatty acids containing 30 to 40% of conjugated dienic acid as the process oil, and the content thereof is preferably 10 to 12 parts by weight based on 100 parts by weight of the raw rubber. If the content of conjugated dienic acid is less than 30%, the reactivity with the polymer is lowered, and if it exceeds 40%, the viscosity tends to increase. If the content of castor oil is less than 10 parts by weight, the viscosity increases, the blending processability is disadvantageous, and if it exceeds 12 parts by weight, there is a problem that the wear performance and fuel efficiency performance is lowered.

In addition, of course, the rubber composition of the present invention may include other additives and compounding agents used in conventional rubber tread rubber compositions.

The present invention can be understood in more detail by the following examples and comparative examples, the following examples are only for illustrating the present invention, and are not intended to limit the protection scope of the present invention.

EXAMPLE

As shown in Table 1, each component was formulated to prepare a rubber composition. Using the prepared rubber specimens, general physical properties such as hardness, modulus, dynamic loss coefficient, and wear resistance were measured and shown in Table 2 below.

(Hardness)

The term refers to the hardness of rubber, which is measured using a Shore A Type hardness tester.

(Dynamic loss factor)

As a measure of the viscoelasticity of rubber, it was measured in the range of low temperature to high temperature (-80 ~ 80 ℃) using RDS (RHEOMETRICS DYNAMIC SPECTROMETER), the lower the value is excellent fuel efficiency and heat generation durability performance, The higher the 0 ° C dynamic loss coefficient, the better the braking performance on wet road surfaces.

(Wear resistance)

LAMBOURN, a laboratory wear tester, is used to measure the loss of rubber (LOSS) caused by friction between rubber specimens and abrasive stone. The smaller the amount lost, the better the wear resistance.

matter content Raw material rubber (% by weight) Hys-1,4-butadiene rubber 40 Butadiene rubber with high vinyl content 40 Butyl rubber 20 Compounding agent (part by weight) Silica 15 Silica coupling agent 3 Carbon black 30 oil 10

test item result Hardness 67 Modulus (300%) 142 Dynamic loss factor 0 ℃: 0.379 70 ℃: 0.159 Wear Factor (DIN) 0.159 g

As a result of applying the rubber produced in the composition of the present invention to the tire, the wear loss is advantageous because the wear loss is low, the hysteresis loss at high temperature (70 ° C., tanδ) is low, the R / R is low, and the fuel efficiency is favorable, and the braking is also excellent. It can be seen that the performance is maintained even at the performance (0 ° C., tan δ), and the tire is also excellent in durability.

As described above, according to the present invention, by adding carbon black and silica as a reinforcing agent to a raw material rubber containing high cis-1,4 butadiene rubber, butadiene rubber having a high vinyl content, and butyl rubber, various physical properties may be excellent. In addition, wear performance is advantageous because the wear loss is low, the hysteresis loss at high temperature is low, the fuel economy performance is advantageous, and also good performance in the braking performance, it can be seen that also excellent tire durability.

Claims (6)

Carbon black 30-40 based on 100 parts by weight of the raw rubber comprising 40-50% by weight of high cis-1,4 butadiene rubber, 40-50% by weight of butadiene rubber having a high vinyl content, and 10-20% by weight of butyl rubber The rubber composition for tire treads containing a weight part and 10-20 weight part of silicas. The rubber composition for tire treads according to claim 1, wherein the high cis-1,4 butadiene rubber is a polybutadiene rubber having a sheath content of 70 to 90% by weight and a vinyl content of 2 to 10% by weight. The rubber composition for tire treads according to claim 1, wherein the butadiene rubber having a high vinyl content is a rubber having a vinyl content of 80% by weight or more and a glass transition temperature of -15 to -20 ° C. The rubber composition for a tire tread according to claim 1, wherein the carbon black has an iodine adsorption amount of 130 to 140 mg / g, a DBP oil absorption amount of 135 to 145 cm 3/100 g, and an agglomeration size distribution of 58 to 65. The rubber composition for a tire tread according to claim 1, wherein the silica has an iodine adsorption amount of 160 to 180 mg / g and a DBP oil absorption of 230 to 240 cm 3/100 g. The rubber composition for tire tread according to any one of claims 1 to 5, further comprising 2 to 4 parts by weight of a silica coupling agent and 10 to 12 parts by weight of caster oil.