KR100782969B1 - Rubber composition for tire tread for an automobile - Google Patents

Abstract

A tire tread rubber composition for automobiles is provided to improve abrasion resistance, gasoline mileage efficiency, traction performance and handling performance. A tire tread rubber composition comprises 100 parts by weight of a rubber material which comprises 30-70 wt% of a solution polymerization styrene-butadiene rubber (S-SBR 2) containing 15-30 % of styrene and 60 % or more of vinyl component and having a glass transition temperature of -27 to -30 deg.C and an average molecular weight of 700,000 or more and 30-70 parts by weight of a solution polymerization styrene-butadiene rubber (S-SBR 3) containing 32-47 % of styrene and 50 % or more of vinyl component and having a glass transition temperature of -25 to -28 deg.C and an average molecular weight of 1,500,000 or more; 60-100 parts by weight of silica as a reinforcing filler; and 3-10 parts by weight of a silane coupling agent.

Description

Tire composition for tire tread for an automobile

The present invention relates to a rubber tread rubber composition for passenger cars, and more particularly, to a rubber tread for passenger car tire treads having improved fuel economy performance, handling performance and wet braking performance.

Due to the high performance of passenger cars, consumers are demanding high performance of tires. In particular, the demand for tires with excellent wear resistance and low fuel consumption, as well as adjustable stability and braking performance, is actively considering the application of new new concept materials. Tire technology, which combines the adjustment stability and braking performance of these tires at the same time, has brought significant advances, especially in the field of materials. For example, as styrene-butadiene copolymer rubber produced by emulsion polymerization is produced by solution polymerization method and the technology to adjust its microstructure is commercialized, it has taken a step further to improve the control stability and braking performance at the same time. As the organic reinforcing filler, which was represented by carbon black, appeared as an inorganic reinforcing agent called silica, further improvement of tire performance was made.

In general, it is known that the use of rubber having a low Tg (glass transition temperature) can improve tire wear performance and fuel economy. However, it is known that stability (braking performance) is rather deteriorated. When the amount of reinforcing filler is used to compensate for the deterioration of the stability of the tire, braking performance is improved, but fuel efficiency is disadvantageous. Thus, each performance of a tire shows that when one performance is improved, the other performance is degraded. Therefore, the performance of a tire that can improve one performance while minimizing the other performance degradation or even two performances simultaneously can be improved. Development will be the key to further progress.

Meanwhile, in Europe, the demand for the use of environmentally friendly materials is increasing in relation to environmental regulations. There are many kinds of softeners among the additives of the tread rubber composition of the tire for passenger cars, but in general, aromatic oils are known to realize processability and optimum properties in refining and extrusion processes. However, with the recent increase in environmental awareness, when the content of polycyclic aromatic carbon (PAH) in aromatic oils is more than 3% by weight, it is known that cancer is likely to be caused. The European Rubber Association (BRIC) has accepted this result. In the EU, specific measures for use have been set up in the EU. When the content is more than 3% by weight, the law prohibiting the sale after January 1, 2010 makes all tire makers think that this should be solved urgently.

As mentioned above, the market demands both high performance of tires and the use of environmentally friendly materials, so technology related to the discovery of environmentally friendly materials and the improvement of tire performance using the same has been a hot topic in the industry.

In order to solve this technical problem, the present invention provides a solution-polymerized styrene butadiene rubber having excellent compatibility with silica and styrene butadiene rubber prepared using an oil having excellent low temperature characteristics and low fuel consumption performance as well as environmentally friendly properties as a raw material rubber. It is an object of the present invention to provide a tire tread composition for a passenger car which is excellent in low fuel consumption performance and wear resistance as well as braking performance by using an appropriate amount of silica as a reinforcing filler.

Tire tread rubber composition of the present invention for achieving the above object is a solution-polymerized styrene butadiene rubber (S-SBR 3 and S-SBR having a high molecular weight and high styrene and vinyl content in 100 parts by weight of the raw rubber) 4) 30 to 70 parts by weight of silica with 60 to 100 parts by weight of reinforcing filler mixed with 30 to 70 parts by weight of solution-polymerized styrene butadiene rubber (S-SBR 2) having high compatibility with silica and high vinyl content. It is characterized by improving the adjustment stability performance, low fuel consumption performance, wear resistance performance and braking performance at the same time. In addition, the present invention is to obtain an environmentally friendly rubber composition by producing a polymer using an environmentally friendly oil (PAHs content of less than 3% by weight) with a high purity, low temperature characteristics and excellent heat resistance performance and minimized harmful substances content do.

The raw material rubber of the present invention can be largely divided into three, the first is a solution polymerization styrene butadiene rubber having a high affinity with silica and a styrene content of 15 to 30%, a vinyl content of 60% or more (S-SBR 2 ), It is used in 30 to 70 parts by weight of the total raw material rubber. In addition, the glass transition temperature of the styrene butadiene rubber is -27 to -30 ℃, the weight average molecular weight satisfies the value of 700,000 or more.

When the styrene content in the solution-polymerized styrene butadiene rubber (S-SBR 2) is out of the above range, fuel efficiency, wear performance and processability are disadvantageous, and when the vinyl content is less than 60%, braking performance is disadvantageous. Further, when the weight average molecular weight is less than 700,000, wear performance, handling performance, braking performance, and the like become disadvantageous. In addition, if the glass transition temperature is out of the above range, it is difficult to implement the optimum performance, such as wear performance, braking performance, handling performance, it is preferable that the molecular weight, glass transition temperature and the microstructure content satisfy the above range.

Secondly, 30 to 70 parts by weight of a solution-polymerized styrene butadiene rubber (S-SBR 3) having a styrene content of 32 to 47% and a vinyl content of 50% or more, and a styrene content of 35 to 50% and a vinyl content of 40% or more. Solution polymerization styrene butadiene rubber (S-SBR 4) 30 to 70 parts by weight. In addition, the glass transition temperature of the styrene butadiene rubber (S-SBR 3) is -25 to -28 ℃, the weight average molecular weight is 1,500,000 or more, the styrene butadiene rubber (S-SBR 4) has a glass transition temperature- It is 29-32 degreeC, and a weight average molecular weight satisfies the value of 1,600,000 or more.

If the styrene content in the solution-polymerized styrene-butadiene rubber (S-SBR 3 and S-SBR 4) is out of the above range, fuel economy performance, wear performance and workability are disadvantageous, and braking performance when the vinyl content is less than 40% This is disadvantageous. In addition, when the weight average molecular weight is less than 140,000, wear performance, handling performance, braking performance, and the like are disadvantageous, so that the molecular weight, the glass transition temperature, and the microstructure preferably satisfy the above range.

On the other hand, in the present invention, 60 to 100 parts by weight of silica is included with respect to 100 parts by weight of the raw material rubber as a filler. The smaller the amount of filler added, the more favorable the fuel efficiency, but the disadvantage in terms of wear performance and braking performance. Therefore an optimum amount of addition is required.

In addition, in the present invention, an environmentally friendly rubber composition is obtained by using a polymer using an environmentally friendly oil (PAHs content of 3 wt% or less) having high purity, low temperature characteristics, and fuel efficiency, and minimizing harmful substance content as a softener. . When the content of the silane coupling agent is less than 3 parts by weight and more than 10 parts by weight, fuel efficiency, abrasion resistance, braking performance, and the like are disadvantageous, and the above range is preferably satisfied.

In the present invention, of course, in addition to the above composition, additives such as anti-aging agents, vulcanizing agents, vulcanization accelerators, etc., which are added to ordinary tire tread rubber compositions can be added.

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

<Examples and Comparative Examples>

 Rubber Compositions of Comparative Examples and Examples Item Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Example 1 Example 2 S-SBR 1 82.5 E-SBR 1 55 S-SBR 2 82.5 68.75 103.13 34.38 34.38 68.75 68.75 E-SBR 2 55 68.75 34.38 S-SBR 3 103.13 68.75 S-SBR 4 103.13 68.75 Silica 75 75 78 78 81 81 83 83 Silane Coupling Agent ¹ 6.5 6.5 7 7 7.5 7.5 8 8 Wear resistance 100 102 103 104 101 102 106 105 Fuel efficiency 100 103 104 105 106 107 108 110 Braking characteristics 100 102 104 102 106 107 108 109 Handling performance 5.5 5.75 6.25 6.25- 6.5 6.5+ 6.75 6.75+ (1) X50S (Degussa) is used as a compounding agent to improve the dispersion of silica. In the case of X50S, the silane coupling agent and carbon black are mixed at a ratio of 1: 1, so the actual amount of silane coupling agent is 1/2 of the X50S input amount. The oil of S-SBR & E-SBR 137.5 PHR contains 37.5 PHR.

* Antioxidant: 5 parts by weight, zinc oxide: 3 parts by weight, stearic acid: 1.5 parts by weight, sulfur: 2.5 parts by weight, vulcanization accelerator: 2.0 parts by weight was commonly used in all comparative examples and examples.

* Solution polymerization S-SBR and emulsion polymerization E-SBR used as the raw material rubber includes a softener as shown in Table 2 below.

The performance of the rubber compositions specified in Table 1 was compared by the following method.

1) Abrasion Resistance Index: Tested by Rambon Abrasion Tester, the higher the index, the better the wear resistance.

2) Braking performance and fuel efficiency: measured by Rheometrics Dynamic Spectrometer, the larger the index value, the better the braking performance and fuel efficiency.

3) Handling characteristics: The test composition was prepared by applying the rubber composition proposed in the invention to the tire tread part, and the various testability and stability were evaluated by directly mounting the prepared test tire on the vehicle. (Specification: 195 / 65R15T)

Comparative Example 1

As shown in Table 1, 82.5 parts by weight of solution-polymerized styrene butadiene 1 (S-SBR 1) rubber, 75 parts by weight of silica, 6.5 parts by weight of silane coupling agent, and 55 parts by weight of emulsion-polymerized styrene butadiene 1 (E-SBR 1); 5 parts by weight of antioxidant, 3 parts by weight of zinc oxide, 1.5 parts by weight of stearic acid, 2.5 parts by weight of sulfur, 2 parts by weight of vulcanization accelerators were formulated to prepare a rubber composition, which was vulcanized at 160 ℃ to prepare a rubber specimen.

Comparative Example 2

A solution was prepared in the same manner as in Comparative Example 1 except that 82.5 parts by weight of styrene butadiene 2 (S-SBR 2) rubber and 55 parts by weight of emulsion polymerization styrene butadiene 2 (E-SBR 2) were used.

Comparative Example 3

68.75 parts by weight of solution-polymerized styrene butadiene 2 (S-SBR 2) rubber, 68.75 parts by weight of emulsion polymerization styrene butadiene 2 (E-SBR 2) except that 78 parts by weight of silica and 7 parts by weight of silane coupling agent are used. Was prepared in the same manner as in Comparative Example 1.

[Comparative Example 4]

Solution polymerization Styrene butadiene 2 (S-SBR 2) 103.13 parts by weight of rubber, emulsified polymerization styrene butadiene 2 (E-SBR 2) 34.38 parts by weight, except that a specimen was prepared in the same manner as in Comparative Example 3.

[Comparative Example 5]

34.38 parts by weight of solution-polymerized styrene butadiene 2 (S-SBR 2) rubber, 81 parts by weight of silica and 7.5 parts by weight of silane coupling agent based on 103.13 parts by weight of solution-polymerized styrene butadiene 3 (S-SBR 3) A specimen was prepared in the same manner as in Comparative Example 4.

Comparative Example 6

Solution polymerization Styrene Butadiene 4 (S-SBR 4) A specimen was prepared in the same manner as in Comparative Example 5 except for using 103.13 parts by weight.

Example 1

68.75 parts by weight of solution-polymerized styrene butadiene 2 (S-SBR 2) rubber, 81 parts by weight of silica and 7.5 parts by weight of silane coupling agent based on 68.75 parts by weight of solution-polymerized styrene butadiene 3 (S-SBR 3) Was prepared in the same manner as in Comparative Example 1.

Example 2

68.75 parts by weight of solution-polymerized styrene butadiene 2 (S-SBR 2) rubber, 81 parts by weight of silica and 7.5 parts by weight of silane coupling agent, based on 68.75 parts by weight of solution-polymerized styrene butadiene 4 (S-SBR 4) Was prepared in the same manner as in Comparative Example 1.

S-SBR Characteristics Comparison S-SBR Type Styrene Content (%) Vinyl content (%) Tg (℃) Weight average molecular weight Types of Oil Contained S-SBR 1 23 58 -24 to -26 More than 600,000 A # 2 (Oil A) E-SBR 1 38 18 -34 to -38 More than 900,000 A # 2 (Oil A) S-SBR 2 25 65 -27 to -30 More than 730,000 TDAE (OilB) E-SBR 2 40 18 -36 to -39 1,100,000 or more TDAE (Oil B) S-SBR 3 38 57 -25 to -28 1,500,000 or more SRAE (OilC) S-SBR 4 44 48 -29 to -32 1,600,000 or more TDAE (Oil B) Note: A # 2 is Aromatic oil, TDAE is Treated Distillate Aromatic Extracts Oil, and SRAE is Safe Residual Aromatic Extracts Oil.

1.Oil-A: PAH content is 3% by weight or more, kinematic viscosity 90, aromatic components 40% by weight, naphthenic components 35% and paraffin components containing 25% by weight.

2. Oil-B: PAH content is 3 wt% or less, kinematic viscosity is 95, aromatic component is 20 wt%, naphthenic component is 32% and paraffin component is 48 wt%.

3. Oil-C: PAH content is 3 wt% or less, kinematic viscosity 140, aromatic components 22 wt%, naphthenic components 22% and paraffin components 56% by weight.

4. Braking performance and low fuel consumption: 0.5% strain, 10 Hz, Temp. Measure 0 ° C tanδ and 60 ° C tanδ by sweep.

Oil-A (Aromatic Oil), Oil-B (TDAE Oil), and Oil-C (SRAE Oil) exhibit different performances in rubber compositions due to different glass transition temperatures (Tg) due to different components. . Oil-B and Oil-C have lower glass transition temperatures than Oil-A, which is superior to Oil-A in terms of wear resistance and fuel efficiency, but has a disadvantage in terms of braking performance. Therefore, in order to supplement the disadvantages while utilizing the advantages of Oil-B and Oil-C, in the present invention, the microstructure of the styrene butadiene rubber (S-SBR 2 to 4 and E-SBR 2) is first worn and braked. It was designed and applied to favor performance and adjustment stability performance. This is shown well in the performance test results of Comparative Examples and Examples of Table 1.

First, the comparative examples 2, 3, and 4 show the effect at the time of applying an emulsion polymerization styrene butadiene rubber. Secondly, the brake performance and the abrasion resistance were not good when the rubber blending ratio was out of the comparative examples 5 and 6. Third, as shown in Examples 1 and 2, performance can be further improved by applying an appropriate rubber compounding ratio and applying an appropriate amount of silica so as to improve braking performance and adjusting stability without deteriorating fuel efficiency and wear performance. Acquired skills.

In the present invention, a solution polymerization styrene butadiene (S-SBR 3 and S-SBR) designed to improve wear resistance, braking performance, and adjustment stability without deteriorating fuel efficiency and using an optimal amount of filler to maximize the performance of the rubber composition. 4) A tread rubber composition having excellent performance was obtained by mixing rubber.

30-70 wt% of solution-polymerized styrene butadiene rubber (S-SBR 2) and 30-70 wt% of solution-polymerized styrene butadiene rubber (S-SBR 3) or solution-polymerized styrene butadiene rubber (S-SBR 4) ) Tire tread rubber composition for passenger cars comprising 60 to 100 parts by weight of silica as a reinforcing filler and 3 to 10 parts by weight of silane coupling agent based on 100 parts by weight of raw rubber including 30 to 70% by weight, However, it has an excellent effect on braking performance and handling performance.

Claims (5)

Silica as a reinforcing filler for 100 parts by weight of raw material rubber containing 30 to 70 parts by weight of solution-polymerized styrene butadiene rubber (S-SBR 2) and 70 to 30 parts by weight of solution-polymerized styrene butadiene rubber (S-SBR 3) Tire tread rubber composition for passenger cars comprising 60 to 100 parts by weight, 3 to 10 parts by weight of a silane coupling agent. Here, the solution-polymerized styrene butadiene rubber (S-SBR 2) has a styrene content of 15 to 30%, a vinyl content of 60% or more, a glass transition temperature of -27 to -30 ° C, a weight average molecular weight of 700,000 or more, and solution polymerization styrene The ethylene butadiene rubber (S-SBR 3) has a styrene content of 32 to 47%, a vinyl content of 50% or more, a glass transition temperature of -25 to -28 ° C, and a weight average molecular weight of 1,500,000 or more. To 100 parts by weight of the raw material rubber containing 30 to 70 parts by weight of solution-polymerized styrene butadiene rubber (S-SBR 2) and 70 to 30 parts by weight of solution-polymerized styrene butadiene rubber (S-SBR 4), silica as a reinforcing filler Tire tread rubber composition for passenger cars comprising 60 to 100 parts by weight, 3 to 10 parts by weight of a silane coupling agent. Here, the solution-polymerized styrene butadiene rubber (S-SBR 2) has a styrene content of 15 to 30%, a vinyl content of 60% or more, a glass transition temperature of -27 to -30 ° C, a weight average molecular weight of 700,000 or more, and solution polymerization styrene The styrene butadiene rubber (S-SBR 4) has a styrene content of 35-50%, a vinyl content of 40% or more, a glass transition temperature of -29 to -32 ° C, and a weight average molecular weight of 1,600,000 or more. delete delete delete