KR20010106744A - Tire tread composition - Google Patents

Abstract

The present invention relates to a rubber composition for tire treads, comprising styrene-butadiene rubber having a glass transition temperature of -50 to -10 ° C, wherein D50 is 5.0 or less, BET specific surface area is 400 m 2 / g or less, and CTAB Silica having a specific surface area of 400 m 2 / g or less, which can improve the rolling resistance while maintaining the wear performance or the braking performance can provide a rubber for tire tread that can lower fuel economy.

Description

Rubber tread composition for tire treads

The present invention relates to a rubber tread rubber composition, and more particularly, by using a specific silica, and by using a part of the styrene-butadiene rubber having a glass transition temperature of -50 to -10 ℃, wear resistance, braking performance and fuel efficiency performance An improved rubber composition for tire treads.

As the tire industry develops, we are expanding our technology to produce low fuel consumption, low rolling resistance, and environmentally friendly products. For this purpose, the first concern is to improve the interaction between the carbon black and the polymer which is most widely used as a reinforcing agent. However, there is a limit in the nature of the carbon black, silica has been proposed as a solution. However, silica was not easily miscible with nonpolar rubber due to its strong polarity. In order to solve this problem, coupling agents have been introduced.

Therefore, it was possible to improve the interaction between the silica and the polymer, and from this point on, tire technology using silica began to develop remarkably.

On the other hand, a coupling agent having two functional groups (also referred to as a silane coupler) acts to enhance the reinforcement of the inorganic filler by acting to chemically bond the interaction with the inorganic filler used as a polymer reinforcement agent. Known.

Initially, the glass fiber, which is a resin reinforcing agent, was used to improve the reinforcement properties. However, its use has recently been expanded, and has been used for surface treatment of inorganic materials, solidification of active materials, and production of tires using silica as a reinforcing agent.

In these coupling agents, the inclusion of sulfur in a portion capable of bonding with a polymer is commonly used by tire manufacturers, where the reaction with the polymer is monosulfide, disulfide, and polysulfite. have.

Examples of using a coupling agent containing sulfur include U.S. Patent Nos. 3,798,196, 3,842,111, 3,978,103, 4,444,936, 4,012,403, 4,044,037, 5,675,014, and European Patent No. 0018094. Can be.

On the other hand, in the case of a tread rubber composition used in a conventional low fuel efficiency tire, it is very difficult to simultaneously improve braking performance and wear resistance on wet road surfaces with low fuel efficiency.

In order to solve the problem of low braking performance on wet roads, conventionally, the use of carbon black is increased, or by using rubber with high glass transition temperature, the braking performance is improved on wet roads while partially sacrificing low fuel consumption. I wanted to.

In order to solve the problem of low wear resistance, butadiene rubber is used or carbon black is used. However, the use of butadiene rubber causes a problem that the braking performance on the wet road surface is deteriorated, the increase of carbon black has a problem of lowering the low fuel consumption performance.

Therefore, the inventors of the present invention are trying to solve the problem that the conventional method for improving wear resistance and braking performance does not achieve low fuel efficiency, using rubber having a specific glass transition temperature, and adding precipitated silica with specific characteristics. As a result, it was found that braking performance, abrasion resistance, and low fuel efficiency can be improved, and thus, the present invention has been completed.

Accordingly, an object of the present invention is to provide a rubber tread rubber composition having improved rolling resistance while maintaining wear resistance and braking performance.

The rubber composition for tire treads of the present invention for achieving the above object is a rubber composition consisting of a raw material rubber, a reinforcing agent, a softener, zinc oxide, stearic acid, a processing aid, a vulcanizing agent and a vulcanization accelerator, wherein the raw material rubber has a glass transition temperature- 30 to 100 parts by weight of styrene-butadiene rubber having a temperature of 50 to 10 ° C, and silica is characterized by having a D50 of 5.0 µm or less.

The rubber composition for tire treads of this invention adds specific silica to the rubber composition for tire treads normally.

The silica added in the present invention is a silica having a D50 of 5.0 μm or less, wherein the measurement of D50 (μm) is performed after pretreatment in a constant form even if the silica has any form such as powder, granule, and micro pearl. The pretreated silica is dispersed in water and constant energy is applied. After sonication for about 5 minutes, the silica particle size distribution is measured using a laser scatterer. The smaller this value is, the better the silica is used as a criterion for dispersion. Moreover, it is preferable that silica has a BET value of 400 m <2> / g or less, and a CTAB value of 400 m <2> / g or less.

If the silica deviates from the above standard, it may cause not only the problem of slowing the vulcanization time but also the problem of impossible processing in the field.

On the other hand, the raw material rubber of the present invention is a butadiene rubber or styrene-butadiene rubber, it should contain 30 to 100 parts by weight of styrene-butadiene rubber having a glass transition temperature of at least -50 ~ -10 ℃. By using 30 parts by weight or more of a rubber having a glass transition temperature of -50 to -10 ° C, it is possible to improve braking performance on wet road surfaces. As the styrene-butadiene rubber used in the present invention, any styrene-butadiene rubber having a glass transition temperature of -50 to -10 ° C can be used.

In addition to the raw material rubber and silica described above, the rubber composition of the present invention contains a softening agent, a zinc oxide and stearic acid as a vulcanizing agent, a processing aid, a vulcanizing agent, a vulcanization accelerator, and a coupling agent which are added to a rubber composition for a tire tread. to be.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by the Examples.

Examples 1-4 and Comparative Examples 1-3

The conditions of the silica used in the Examples and Comparative Examples are shown in Table 1 below.

Including such silica, as shown in the following Table 2, the raw material rubber, softener, zinc oxide and stearic acid as a vulcanizing agent, processing aids, vulcanizing agent and vulcanization accelerator, and coupling agent were added in a banbury mixer after mixing Emitted at

To explain in detail step by step, first of all the raw material rubber 2/3 reinforcing agent and coupling agent, zinc oxide, stearic acid, and softener was added in a Banbury mixer and then mixed at 100 ℃. Then, 1/3 of the reinforcing agent, the coupling agent, the softening agent, and the processing aid were added to the obtained compound rubber, mixed in a Banbury mixer, and then discharged at 160 ° C. Finally, the vulcanizing agent and the vulcanization accelerator were added thereto, mixed in a Banbury mixer, and released after 1 minute and 30 seconds.

CTAB (㎡ / g) BET (㎡ / g) D50 (μm) Silica A 157 156 6.5 B 150 218 5.4 C 167 179 4.6 D 160 159 2.3 E 147 216 2.6 F 110 111 3.7

(Unit: parts by weight) Example Comparative example One 2 3 4 One 2 3 Synthetic rubber KBR31 33 33 33 33 33 33 33 s-SBR 76 76 76 76 76 76 76 Silica A - - - - 80 85 - B - - - - - - 80 C 80 - - - - - - D - 80 - - - - - E - - 80 - - - - F - - - 80 - - - Coupling Agent (Si-69) 6.4 6.4 6.4 6.8 6.4 6.4 6.4 Softener (A # 2 Oil) 31 31 31 31 31 31 31 Zinc oxide 3 3 3 3 3 3 3 Stearic acid 2 2 2 2 2 2 2 Processing aid 1.5 1.5 1.5 1.5 1.5 1.5 1.5 brimstone 1.4 1.4 1.4 1.4 1.4 1.4 1.4 accelerant 1.7 1.7 1.7 1.7 1.7 1.7 1.7 Accelerator (DPG) 2 2 2 2 2 2 2 KBR31: A # 2 Oil 37.5 phr extended BRs-SBR: Solution polymerization styrene-butadiene rubber with glass transition temperature of -20 ℃

Experimental Example

The physical properties of the rubber products obtained according to Examples 1 to 4 and Comparative Examples 1 to 3 were measured, and the results are shown in Table 3 below.

Example Comparative example One 2 3 4 One 2 3 300 modulus (MPa) 12.1 13.0 11.8 13.3 12.0 12.5 12.2 Elongation () 385 395 413 385 412 390 405 Wear (g) 0.087 0.087 0.090 0.079 0.090 0.089 0.090 tanδ 0 ℃ 0.630 0.624 0.636 0.499 0.616 0.610 0.584 60 ℃ 0.141 0.143 0.142 0.125 0.142 0.145 0.143

In Table 3, the wear degree is PICO abrasion, 0 ° C tan δ indicates the braking characteristics, the higher the value means the better braking performance. 60 ° C tan δ represents rotational resistance, and the lower the value, the better the performance.

From the results of Table 3, it can be seen that in the case of Examples 1 to 4, the use of a D50 of 5.0 or less improved the rotational resistance performance while the abrasion performance and the braking performance were equal or more than those of the Comparative Examples 1 to 3, which were not.

As described in detail above, according to the present invention, styrene-butadiene rubber having a glass transition temperature of -50 to -10 ° C is contained as a raw material rubber of 30 to 100 parts by weight in the total rubber composition, and a silica having a D50 of 5.0 µm or less is added. In the case of the rubber composition, it is possible to provide a tire tread rubber which can improve the rolling resistance while maintaining the wear performance or the braking performance.

Claims (3)

In a rubber composition comprising a raw material rubber, a reinforcing agent, a softening agent, zinc oxide, stearic acid, a processing aid, a vulcanizing agent, a vulcanization accelerator and a coupling agent, The raw material rubber contains 30 to 100 parts by weight of styrene-butadiene rubber having a glass transition temperature of -50 to -10 ° C, and silica has a D50 of 5.0 µm or less. The rubber composition for a tire tread according to claim 1, wherein the silica has a BET specific surface area of 400 m 2 / g or less and a CTAB specific surface area of 400 m 2 / g or less. The rubber composition for tire treads according to claim 1 or 2, wherein the silica is contained in an amount of 10 to 120 parts by weight based on 100 parts by weight of the raw material rubber.