KR100506841B1 - Silica-filled tread compound of PCR tire - Google Patents

Abstract

The present invention relates to a tread rubber composition for passenger car tires using silica having improved braking performance and heat resistance on wet roads as a reinforcing material, and having a BET value of 130 to 200 m 2 / g based on 100 parts by weight of raw material rubber. 80 weight part and 4-10 weight part of tetraethoxysilyl propyl disulfide which is a disulfide compound as a coupling agent.

As described above, according to the present invention, by applying tetraethoxysilyl propyl disulfide as a coupling agent instead of tetraethoxysilyl propyl tetrasulfide, braking performance and heat resistance on wet roads are greatly improved, thereby improving tire life.

Description

Silica-filled tread compound of PCR tires

The present invention relates to a tread rubber composition for a passenger car tire using silica having improved braking performance and heat resistance on wet roads as a reinforcing material.

In recent years, rubber compositions for applying silica as a reinforcing filler have been increasing in rubber used in tires. However, when the silica is used in a rubber composition, the viscosity is increased due to poor dispersion, and the rubber property is decreased due to the gelation reaction when it is left for a long time.

In order to prevent the above problems, dispersing aids, process oils and coupling agents are used to improve the dispersibility of silica.

The silane coupling agent acts as a crosslinking linkage between the silanol group on the silica surface used as a reinforcing agent and the rubber material of the rubber composition, and when used alone, the silane coupling agent serves to crush the strong cohesion between silica and silica. However, the coupling agent has a disadvantage that the price is expensive and ethanol is volatilized in the process.

At present, the most commonly used coupling agent is tetraethoxysilyl propyl tetrasulfide, and 6 to 10% of the silica addition amount is applied. However, the coupling agent has a disadvantage of low stability at high temperature and high energy consumption when blending.

In order to achieve the above object, the present invention, in the tread rubber composition to which silica is applied, by applying tetraethoxysilyl propyl disulfide instead of tetraethoxy silyl propyl tetrasulfide (TESPT) as a coupling agent on a wet road surface The purpose is to improve braking performance and heat resistance performance.

In order to achieve the above object, the present invention is a known tread rubber composition for passenger car tires, wherein 40 to 80 parts by weight of silica having a BET value of 130 to 200 m 2 / g and a coupling agent are disulfide compounds with respect to 100 parts by weight of the raw material rubber. Tetraethoxysilyl propyl disulfide 4 to 10 parts by weight.

When the silica is added in less than 40 parts by weight, there is a problem that the grip performance on the wet road surface is significantly reduced, and when the silica is added in excess of 80 parts by weight, dispersibility in the rubber compound is lowered to the finished product It shows uneven wear characteristics in the phase.

In addition, when the tetraethoxysilyl propyl disulfide is added in less than 4 parts by weight, a problem occurs that the reactivity between silica and rubber is weak, and when the tetraethoxysilyl propyl disulfide is added in excess of 10 parts by weight, When the rubber is mixed at high temperatures, the crosslinking reaction with the rubber proceeds excessively, resulting in a decrease in modulus and hardness, and an increase in the cost of the rubber compound.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to these examples.

Comparative Example

As shown in the following Table 1, 70 parts by weight of silica, 3 parts by weight of zinc, 3 parts by weight of stearic acid, 2 parts by weight of antioxidant based on 100 parts by weight of the raw material rubber consisting of 75 parts by weight of styrene-butadiene rubber and 25 parts by weight of butadiene rubber Parts, tetraethoxysilyl propyl tetrasulfide (TESPT) 6.1 parts by weight, vulcanizing agent 2 parts by weight, accelerator 1 (CZ) 1.9 parts by weight, and accelerator 2 (DPG) 0.4 parts by weight, using a Banbury mixer tread rubber Specimen was prepared.

<Example 1>

Except for applying 4.2 parts by weight of tetraethoxysilyl propyl disulfide instead of tetraethoxysilyl propyl tetrasulfide (TESPT) was prepared rubber specimens using the same composition, composition and method as in the comparative example.

<Example 2>

Except for applying 5.6 parts by weight of tetraethoxysilyl propyl disulfide instead of tetraethoxysilyl propyl tetrasulfide (TESPT) was prepared rubber specimens using the same composition, composition and method as in the comparative example.

Table 1 Rubber compositions of Comparative Examples and Examples 1 and 2

division Comparative example Example 1 Example 2 Styrene Butadiene Rubber 75 75 75 Butadiene rubber 25 25 25 Silica 70 70 70 Zincification 3 3 3 Stearic acid 2 2 2 Anti-aging 2 2 2 TESPT 5.6 0 0 Tetraethoxysilyl disulfide 0 4.2 5.6 Vulcanizing agent 2 2 2 Accelerator 1 (CZ) 1.9 1.9 1.9 Accelerator 2 (DPG) 0.4 0.4 0.4

<Test Example>

Comparative Examples and Examples The rubber specimens were measured for physical properties according to ASTM-related regulations, and the results are shown in Table 2 below.

(1) TAN δ @ 0 ° C. is used as a substitute for the adjustment stability of the tire (ie, handling performance), and the higher the value, the better the handling performance.

(2) TANδ @ 70 ℃ is used as a substitute value for the rolling resistance value of the tire, and the lower the value, the better the rolling resistance.

(3) Heat build-up

Perry Machinery's hysteresis testing machine is used to measure the elevated temperature by applying a constant stroke to the specimen, indicating that the smaller the temperature difference between the initial temperature and the final temperature of the specimen, the better the performance.

(4) Rebound

Measurement of the ride comfort of the vehicle and an index indicating the elasticity of the vulcanized rubber.

(5) modulus

The measurement is carried out with a tensile tester (Model 4502) manufactured by Instron, by cutting the specimen into dumbbells. 300% modulus refers to the stress acting on the specimen when the specimen is stretched 300%. The higher the value, the better the performance.

<Table 2> Measurement results of physical properties of Comparative Example and Example 1-2

division Comparative example Example 1 Example 2 Fairness 100 ℃ viscosity 132 114 106 125 ℃ viscosity 100 83 76 Scorch time (t5) 34 43.7 46.5 Torque 54.5 46.8 44.4 Torque 25.1 19.5 17.6 Holding time (t90) (minutes) 20.8 18.6 17.7 Tensile Properties Hardness 71 71 70 300% modulus 116 115 120 The tensile strength 206 204 222 Elongation 479 523 501 Fever (temperature difference) 31.6 29.9 27.6 Rebound (1st) 32.2 33.8 32.5 Tg -25.4 -25.4 -29.4 Tanδ @ 0 ℃ 0.243 0.253 0.270 Tanδ @ 70 ℃ 0.131 0.126 0.117

As shown in Table 2, the physical property measurement results are as follows.

1) The embodiment according to the present invention can be seen that the equivalent to the comparative example in terms of tensile properties and rebound performance.

2) It can be seen that the embodiment according to the present invention is much improved than the comparative example in terms of heat generation performance.

3) The present invention can be seen that the tire adjustment stability and rolling resistance performance is superior to the prior art.

In the tread rubber composition to which silica is applied as described above, braking performance and heat resistance on wet roads are greatly improved by applying tetraethoxysilyl propyl disulfide as a coupling agent instead of tetraethoxysilyl propyl tetrasulfide (TESPT). This also improves tire life.

Claims (1)

In a known tread rubber composition for passenger car tires, 40 to 80 parts by weight of silica having a BET value of 130 to 200 m 2 / g and a tetraethoxysilyl propyl disulfide as a coupling agent to 100 parts by weight of the raw material rubber and a coupling agent. A tread rubber composition for a passenger car tire reinforced with silica, comprising a weight part.