KR100775684B1 - Tire tread rubber composition with silica - Google Patents

Abstract

A rubber composition for tire treads is provided to improve the processability and to ensure improved braking performance on a wet road surface by virtue of a decreased wet braking distance. A rubber composition for tire treads comprises: 100 parts by weight of a rubber blend comprising 35-45 parts by weight of emulsion polymerized styrene-butadiene rubber containing 30-50 wt% of styrene, 10-30 wt% of vinyl and 20-50 wt% of aromatic oil, 20-335 parts by weight of emulsion polymerized styrene-butadiene rubber containing 15-40 wt% of styrene and free from aromatic oil, and 30-40 parts by weight of solution polymerized styrene-butadiene rubber containing 25-35 wt% of styrene, 25-35 wt% of vinyl and 20-50 wt% of aromatic oil and having a Tg of -15 to -25 deg.C; and 50-85 parts by weight of silica.

Description

Rubber composition for tire treads with silica {TIRE TREAD RUBBER COMPOSITION WITH SILICA}

The present invention relates to a rubber tread rubber composition to which silica is applied. More specifically, the processability is improved while applying silica as a reinforcing filler to a mixed rubber composed of two emulsion-polymerized styrene-butadiene rubbers and a solution-polymerized styrene-butadiene rubber. The present invention relates to a rubber tread rubber composition to which silica is applied, which can improve braking performance on wet road surfaces.

The required characteristics of the tire include adjustment stability, ride comfort, fuel efficiency, snow performance, braking performance, abrasion resistance, and the like, and play a major role in enabling the tread rubber to achieve the above-mentioned performance.

The tire tread is the only road contact area in the tire, which protects the carcass and contributes to the effective braking force and maneuverability by securing the friction coefficient between the road surfaces. Especially important tire demand characteristics are wet traction, wear resistance, and rolling resistance. It is quite difficult to develop a rubber that often meets all performances at the same time since the three performances, which often belong to the magic triangle, are trade off.

Recently, in order to improve automobile low fuel efficiency and braking performance on wet roads, a technology of completely or partially replacing carbon black, which has been conventionally used, has been developed. However, the more silica used in the tread rubber composition of the tire, the better these performances, but due to the strong interactions between the hydroxyls of the silica, the dispersion and scorch of the silica during the mixing of the composition. There was a problem with fairness.

An object of the present invention is to solve the above problems, to provide a rubber composition for a tire tread that can improve the processability and improve the braking performance on the wet road surface while applying silica as a reinforcing filler.

The rubber composition for tire treads to which silica of the present invention is applied is characterized in that 50 to 85 parts by weight of silica is applied to 100 parts by weight of a mixed rubber composed of two kinds of emulsion-polymerized styrene-butadiene rubbers and solution-polymerized styrene-butadiene rubbers. do.

The mixed rubber used in the present invention is 35 to 45 parts by weight of emulsion-polymerized styrene-butadiene rubber and 15 to 40% by weight of styrene-butadiene rubber including 30 to 50% by weight of styrene, 10 to 30% by weight of vinyl and 20 to 50% by weight of aromatic oil. 20 to 35 parts by weight of emulsion-polymerized styrene-butadiene rubber containing no aromatic oil and 25 to 35% by weight of styrene, 25 to 35% by weight of vinyl and 20 to 50% by weight of aromatic oil, and Tg is- It is preferable that it consists of 30-40 weight part of solution polymerization styrene-butadiene rubber which is 15-25 degreeC.

When rubber outside the composition ratio is used, high filler-filler interaction of silica when silica is used as a reinforcing filler, hydrophilicity due to polar functional groups present on the surface, and low energy loss Since it is unavoidable, since the fall of fairness, such as the dispersibility and viscosity increase of a silica, arises, it is not preferable.

Silica used in the present invention is BET (value representing the surface of the reinforcing filler) is 110 to 200 m 2 / g, DBP (value representing the structure of the reinforcing filler) is 270 to 310ml / 100g Precipitated silica is preferred. When the BET and DBP are out of the numerical range, it is difficult to expect a fairness improvement effect.

The addition amount of the silica is preferably 50 to 85 parts by weight with respect to 100 parts by weight of the mixed rubber. When the addition amount of the silica is less than 50 parts by weight, the addition amount is small, and thus it is difficult to obtain the effect of adding the reinforcing filler. If it exceeds 85 parts by weight, it is not preferable because problems of processability such as mixing and extrusion are caused.

In the rubber composition of the present invention, additives for conventional rubber compositions, for example, zincated, stearic acid, antioxidants, waxes, aromatic oils, sulfur, accelerators, and the like 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 are not intended to limit the protection scope of the present invention.

Example  And Comparative example

Example

40 parts by weight of emulsion-polymerized styrene-butadiene rubber comprising 41% by weight of styrene, 17% by weight of vinyl and 37.5% by weight of aromatic oil, 25 parts by weight of emulsion-polymerized styrene-butadiene rubber containing 23.5% by weight of styrene And 100 parts by weight of a mixed rubber blended in a proportion of 35 parts by weight of a solution-polymerized styrene-butadiene rubber containing 33% by weight of styrene, 35% by weight of vinyl and 20% by weight of an aromatic oil, wherein BET is 120 m 2 / g and DBP is 300 ml. 80 parts by weight of precipitated silica, which is 100 g, and the other additives described in Table 1 were mixed using an internal mixer to prepare a rubber tread rubber composition. Specimens were prepared from the prepared rubber composition, and physical properties thereof were measured and shown in Table 1 below. The vulcanization of the specimen was vulcanized from high temperature to high pressure using a hot press at an optimum cure time at 160 ° C.

Comparative example

A tread rubber composition for a tire was prepared in the same manner as in Example, except that 80 parts by weight of styrene-butadiene rubber, 20 parts by weight of butadiene rubber, and 6.5 parts by weight of silica coupling agent were used.

Specimens were prepared in the same manner as in the prepared rubber composition, and the physical properties thereof were shown in Table 1 below.

 division  Example Comparative example Mixed rubber (parts by weight) 1) E-SBR = 40 SBR = 80 2) E-SBR = 25 BR = 20 3) S-SBR = 35 - Carbon black - 45 Silica 80 45 Silica coupling agent 11.5 6.5 common RD: 2 parts by weight, K-13: 3 parts by weight, wax: 2 parts by weight, zincation: 3 parts by weight, stearic acid: 2 parts by weight, SDA: 2 parts by weight Sulfur: 2 parts by weight, vulcanization accelerator: 2 parts by weight, DPG: 0.3 parts by weight Pattern viscosity (100 ℃) 80 106  Tensile test Hardness 63 71 300% modulus 99 131 Tensile Strength (kg / ㎠) 210 227 % Elongation 584 522 Dynamic viscoelasticity Tg (℃) -6.6 -11.9 Tan δ (0 ℃) 0.904 0.504 Tan δ (70 ° C) 0.150 0.179 Wet braking distance (m) 36.2 38.7

week)

1) E-SBR: Emulsified polymerized styrene butadiene rubber containing 41 wt% styrene, 17 wt% vinyl and 37.5 wt% aromatic oil

2) E-SBR: Emulsion polymerization styrene-butadiene rubber containing 23.5% by weight of styrene

3) S-SBR: solution-polymerized styrene-butadiene rubber containing 33% by weight of styrene, 35% by weight of vinyl and 20% by weight of aromatic oil and having a Tg of -15 ~ -25 ° C.

* RD: polymerizable 2,2,4-trimethyl-1,2-dihydroquinoline

* K-13: 6PPD 1,3-dimethylbutyl

* SDA: Zn-Soap

* DPG: Diphenylene Glycol

As shown in Table 1, looking at the pattern viscosities, which is an indicator of fairness improvement, the lower the pattern viscosity, the better the fairness. The embodiment of the present invention shows that the fairness is improved compared to the comparative example, and the wet braking is performed. The distance is also shorter than the comparative example, it can be seen that the braking performance on the wet road surface is improved.

As can be seen from the above, the rubber composition for tire treads to which the silica according to the present invention is applied has an effect of improving processability and wet braking performance.

Claims (2)

35 to 45 parts by weight of emulsion-polymerized styrene-butadiene rubber, including 30 to 50% by weight of styrene, 10 to 30% by weight of vinyl, and 20 to 50% by weight of aromatic oil, and 15 to 40% by weight of styrene. Unpolymerized styrene-butadiene rubber solution containing 20 to 35 parts by weight of styrene and 25 to 35% by weight of styrene, 25 to 35% by weight of vinyl and 20 to 50% by weight of aromatic oil and having a Tg of -15 to 25 ° C. -Rubber composition for tire treads comprising 50 to 85 parts by weight of silica with respect to 100 parts by weight of mixed rubber consisting of 30 to 40 parts by weight of butadiene rubber. The rubber composition for tire treads according to claim 1, wherein the silica is precipitated silica having a BET of 110 to 200 m 2 / g and a DBP of 270 to 310 ml / 100 g.