KR100709977B1 - Rubber composition of tire tread for automobile - Google Patents

Abstract

30 to 50 parts by weight of a solution-polymerized styrene-butadiene rubber A having a styrene content of 15 to 30% and a vinyl content of at least 60%; 30-50 parts by weight of a solution-polymerized styrene-butadiene rubber B having a styrene content of 35 to 50% and a vinyl content of 40% or more; And 60 to 90 parts by weight of silica, 15 to 50 parts by weight of a softener, and 10 to 20 parts by weight of a silane coupling agent based on 100 parts by weight of the silica, based on 100 parts by weight of the raw material rubber including 10 to 30 parts by weight of butadiene rubber (BR). The rubber composition for tire treads for passenger cars is prepared by solution polymerization as a raw material rubber and uses two kinds of styrene-butadiene rubbers and butadiene rubbers satisfying specific properties, and uses an optimal filler and a silane coupling agent. By using emulsifiers whose content satisfies international regulatory levels, it is possible to obtain a tread rubber composition with excellent control stability performance and low fuel consumption performance as well as wear and braking performance.

Emulsifier * Braking Performance * Low Fuel Efficiency * Wear Resistance * Tread

Description

Tire composition for tire treads for passenger cars {Rubber composition of tire tread for automobile}

1 is a graph showing a low fuel consumption performance change of the rubber composition according to the amount of filler used.

The present invention relates to a rubber composition for tire treads for passenger cars, and more particularly, to the use of the optimum filler and the flexibility of the compounded rubber to improve the wear performance and the braking performance of two kinds of solution-polymerized styrene-butadiene rubbers. The present invention relates to a tire tread rubber composition for a passenger car, which further improves handling performance, abrasion performance, fuel efficiency, and braking performance by additionally using an environment-friendly softener.

Due to the high performance of passenger cars, consumers are demanding high performance of tires. In particular, the demand for tires that combine stability and low fuel consumption is actively considering the application of new concept materials. The tire technology, which combines the stability and low fuel economy of these tires, has made significant progress, 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 of adjusting the microstructure is commercialized, it has taken a step further to improve the stability and fuel efficiency.

In general, it is known that the use of rubber having a low glass transition temperature (Tg) may improve tire wear performance and fuel economy. However, it is known that stability (braking performance) is rather deteriorated. In order to compensate for the deterioration of the stability of the tire, first, the use of reinforcing fillers is increased. In this case, the braking performance is improved, but the fuel efficiency is detrimental. Increasing the content improves braking performance but adversely affects wear performance.

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 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 polycyclic aromatic (PCA) content 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 established, and the content of Benzo (a) pyrene, or polycyclic aromatic hydrocarbons (PAH), is 1 mg / kg and 8 All tire makers urgently address this by enacting a law prohibiting the sale after January 1, 2010 when the total content of major PAH materials is more than 10 mg / kg or when the PAC content is more than 3% by weight. It's a matter of what to do.

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.

Therefore, the inventors of the present invention, while researching for the development of tire high-performance technology applying the environmentally friendly materials as described above, in the styrene-butadiene rubber manufactured using an oil having high purity, low temperature characteristics and fuel economy performance, while having environmentally friendly characteristics By adding oil-friendly styrene butadiene rubber with high styrene and vinyl content and excellent affinity with silica, eco-friendly oil with excellent low temperature and fuel efficiency, and applying optimum silica content as reinforcing filler The present invention has been found to improve fuel efficiency, as well as improved stability, wear and braking performance.

Accordingly, it is an object of the present invention to provide a rubber composition for tire treads for passenger cars which is excellent in not only adjustment stability, wear performance and braking performance, but also fuel efficiency.

Rubber composition for tire treads for passenger cars of the present invention for achieving the object of the present invention as described above is 30 to 50 parts by weight of a solution polymerization styrene-butadiene rubber having a styrene content of 15 to 30%, a vinyl content of 60% or more; 30-50 parts by weight of a solution-polymerized styrene-butadiene rubber having a styrene content of 35 to 50% and a vinyl content of 40% or more; And 60 to 90 parts by weight of silica, 15 to 50 parts by weight of a softener, and 10 to 20 parts by weight of a silane coupling agent based on the weight of the silica, based on 100 parts by weight of the raw material rubber including 10 to 30 parts by weight of butadiene rubber (BR). It is characterized by that.

The present invention will be described in more detail as follows.

The present invention is made of two kinds of styrene-butadiene rubber and butadiene rubber prepared by solution polymerization, and includes a rubber for a tire tread for passenger cars, which comprises a silica, a silane coupling agent, and a softening agent having a PCA component of less than 3% by weight. It relates to a composition.

The raw material rubber of the present invention can be largely divided into three, the first is a solution polymerization styrene-butadiene rubber A having a high affinity with silica and a styrene content of 15 to 30%, a vinyl content of 60% or more, It is used in 30-50 parts by weight of raw rubber. In addition, the glass transition temperature of the styrene-butadiene rubber is -27 to -30 ℃, molecular weight distribution satisfies the value of 1.3 to 3.0.

When the styrene content in the solution polymerization styrene-butadiene rubber A is out of the above range, low fuel consumption, wear resistance and processability are disadvantageous, and when the vinyl content is less than 60%, braking performance is disadvantageous.

Further, when the molecular weight distribution is less than 1.3, workability is disadvantageous, while when it exceeds 3.0, low fuel consumption, wear resistance, adjustment stability performance, and the like become disadvantageous. In addition, if the glass transition temperature is out of the above range, it is difficult to realize the optimum performance such as wear resistance, braking resistance, adjustment stability performance, etc. For this reason, it is preferable that the glass transition temperature and the molecular weight distribution satisfy the above range.

Secondly, 30-50 parts by weight of a solution-polymerized styrene-butadiene rubber B having a styrene content of 35 to 50% and a vinyl content of 40% or more. Moreover, the glass transition temperature of the said styrene-butadiene rubber B is -29-32 degreeC, and molecular weight distribution satisfies the value of 2.3-4.0.

When the styrene content in the solution polymerization styrene-butadiene rubber B is out of the above range, low fuel consumption, wear resistance and processability are disadvantageous, and when the vinyl content is less than 60%, braking performance is disadvantageous. Further, when the molecular weight distribution is less than 2.3, workability is disadvantageous, and when it exceeds 4.0, low fuel consumption, wear resistance, adjustment stability performance, and the like become disadvantageous. In addition, when the glass transition temperature is out of the above range, it is difficult to realize the optimum performance such as wear resistance, braking resistance, adjustment stability performance, etc. For this reason, it is preferable that the glass transition temperature and the molecular weight distribution satisfy the above range.

Finally, the raw material rubber of the present invention includes butadiene rubber (BR) in 10 to 30 parts by weight of the total raw material rubber, there is a problem that the braking performance and workability is disadvantageous if the content of butadiene rubber is outside this range.

Meanwhile, in the present invention, silica is included as a filler in an amount of 60 to 90 parts by weight based on 100 parts by weight of the raw material rubber. The smaller the amount of filler added, the more favorable the fuel efficiency, but the disadvantage in terms of wear performance and braking performance. In the case of using silica as a filler, it can be seen that the application of the optimum amount of addition improves wear performance and braking performance without deteriorating fuel efficiency. So looking at the optimum range of addition amount of silica as shown in FIG.

As shown in FIG. 1, there is an optimal amount of filler to maximize the specific performance of the tire. In the range below the optimum addition amount, the performance is improved as the amount of the filler is increased, but in the range above the optimum addition amount, the performance decreases as the amount of the filler is increased. As shown in the graph above, even more fillers can be used to obtain the same level of fuel efficiency as before, and excellent wear and braking performance can be obtained compared to conventional rubber compositions. Therefore, the silica in the present invention is effective to obtain the desired physical properties to satisfy the above range.

In addition, in the present invention, 10 to 20 parts by weight of the silane coupling agent with respect to the weight of the silica in order to couple the silica, there is a problem that low fuel consumption, wear resistance and workability when out of the above range.

In the present invention, in order to produce an environmentally friendly rubber composition having high purity, low temperature characteristics and fuel efficiency, and minimizing the content of harmful substances, the polycyclic aromatic component is less than 3% by weight, and has a kinematic viscosity of 95 ° C. It is used at 15 to 50 parts by weight based on 100 parts by weight of rubber.

If the content of the softener is less than 15 parts by weight, workability and braking performance are disadvantageous. If the content of the softener exceeds 50 parts by weight, workability and wear resistance are disadvantageous.

In the commonly used emollient, as a polycyclic aromatic component, as shown in Table 1 below, the total content of the PCA component as described above is less than 3% by weight.

PCA Ingredients Chemical symbol PCA Ingredients Chemical symbol Benzo (a) Pyrene BaP C ₂₀ H ₁₂ Benzo (b) Fluoranthene BbFA C ₂₀ H ₁₂ Benzo (e) Pyrene BeP C ₂₀ H ₁₂ Benzo (j) Fluoranthene BjFA C ₂₀ H ₁₂ Benzo (a) Anthracene BaA C ₁₈ H ₁₂ Benzo (k) Fluoranthene BkFA C ₂₀ H ₁₂ Chrysene CHR C ₁₈ H ₁₂ Dibenzo (a, h) Anthracene BbFA C ₂₀ H ₁₂

In addition, the softener used in the present invention is that the aromatic component is 15 to 25% by weight of the total softener, the naphthenic component is 27 to 37% by weight, and the paraffinic component is 38 to 58% by weight.

In addition to the above components, the tire tread rubber composition of the present invention can be added with additives such as sulfur, vulcanizing agents, anti-aging agents and the like contained in the general tire rubber composition.

Hereinafter, the present invention will be described in more detail with reference to the following Examples, which are not intended to limit the present invention.

Examples 1 to 3 and Comparative Examples 1 to 5

To prepare a rubber specimen by mixing the composition shown in Table 2, and then vulcanized at 160 ℃.

Ingredients (contents: parts by weight) Comparative example Example One 2 3 4 5 One 2 3 Raw Material Rubber ⁽¹⁾ S-SBR 1 65 - - - - - - - S-SBR 2 50 - - - - - - - S-SBR 3 - 65 65 - - - - S-SBR 4 - 50 50 - - - - - S-SBR A - - 65 - 67 65 55 55 S-SBR B - - - 45 43 45 55 55 BR 20 20 20 20 20 20 20 20 Silica 70 70 70 70 80 70 70 80 Silane Coupling Agents ⁽²⁾ 13 13 13 13 14 13 13 14 Anti-aging 3 3 3 3 3 3 3 3 Zinc oxide 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Stearic acid 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 brimstone 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 Vulcanization accelerator 3.2 3.2 3.2 3.2 3.2 3.2 3.2 3.2 Softener Oil-A ⁽³⁾ 3.75 - - - - - - - Oil-B ⁽⁴⁾ 3.75 3.75 3.75 - 3.75 4.25 5 (1) S-SBR 1, 3, A and B of the raw material rubber contains 37.5 parts by weight of oil in 137.5 parts by weight of S-SBR, and S-SBR 2 and 4 are 150 parts by weight of S-SBR. Contains 50 parts by weight of heavy oil. (2) X50S (Degussa) is used as a compounding agent to improve silica dispersion. 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, and the silane coupling agent is based on silica. (3) Oil-A: 3.0 wt% or more of PCA content, kinematic viscosity 90, 40 wt% of aromatic components, 35% of naphthenic components and 25 wt% of paraffinic components. (4) Oil-B: less than 3.0% by weight of PCA content, kinematic viscosity 95, 20% by weight aromatic component, 32% naphthenic component and 48% by weight paraffin component.

Specific components of S-SBR in the raw material rubber used in Table 2 are as shown in Table 3 below.

S-SBR Type Styrene Content (%) Vinyl content (%) Tg (δ) Molecular weight distribution Types of Oil Contained S-SBR 1 23 58 -24 to -26 2.0 to 3.5 A # 2 S-SBR 2 36 23 -30 to -33 2.5 to 4.5 A # 2 S-SBR 3 23 58 -25 to -28 2.0 to 3.5 TDAE S-SBR 4 36 23 -30 to -33 2.5 to 4.5 TDAE SBR A 25 65 -27 to -30 1.3 to 3.0 TDAE SBR B 44 48 -29 to -32 2.3 to 4.0 TDAE Note: A # 2 is aromatic oil and TDAE is Treated Distillate Aromatic Extracts Oil.

The physical properties of the rubber compositions prepared according to the Comparative Examples and Examples were measured as follows, and the results are shown in Table 4 below.

1) Abrasion resistance index: Tested by the Rambon Abrasion Tester, the value of Comparative Example 1 was indexed on the basis of 100. The larger the index, the better the wear resistance.

2) Braking performance and fuel economy: Rheometrics Dynamic Spectrometer, 0.5% strain, 10 Hz, Temp. 0 [deg.] C tanδ and 60 [deg.] C tanδ were measured by sweep and indexed based on the value of Comparative Example 1 as 100. The larger the index, the better the braking performance and the fuel efficiency.

3) Handling characteristics: The test composition was prepared by applying the rubber composition described in the invention to the tire tread portion, and the prepared test tire was directly mounted on the vehicle to evaluate various maneuverability and stability. (Specification: 195 / 60R15T)

Item Comparative example Example One 2 3 4 5 One 2 3 Wear resistance 100 101 104 100 104 104 106 108 Fuel efficiency 100 103 103 99 103 103 104 106 Braking characteristics 100 96 98 104 104 106 110 115 Handling performance 5.75 5.75 6.0+ 6.25 6.5 6.5+ 6.75 7.0+

As can be seen in the results of Table 4, in the case of Comparative Examples 1 and 2 using a conventional raw material rubber, and different types of softeners, Oil-A (Aromatic oil) and Oil-B (TDAE oil) are composed Due to the difference in components, the glass transition temperature (Tg) is different from each other to exhibit different performances in the rubber composition. Oil-B has a lower glass transition temperature than Oil-A, which is superior to Oil-A in terms of wear performance and fuel economy, but has a disadvantage in terms of braking performance.

In order to make use of the advantages of Oil-B and to compensate for the disadvantages, only the improved solution-polymerized styrene butadiene rubber (SBR-5) was applied (Comparative Example 3), but the braking performance was improved. Showed poor results.

In addition, when solution-polymerized styrene butadiene rubber only (SBR-6) was applied (Comparative Example 4), the adjustment stability performance and the braking performance were improved, but the wear performance and fuel economy performance were deteriorated.

In addition, Comparative Example 5 was carried out by using an oil-A having a PCA content of 3% by weight or more, and applying an optimum amount of filler while further using a solution-polymerized styrene-butadiene rubber (S-SBR 5) having improved microstructure. Compared with Example 1, the fuel efficiency and abrasion performance were not deteriorated, but the braking performance and the adjustment stability were deteriorated.

Therefore, in Examples 1 to 3 having the same composition as the present invention, by using an optimal amount of filler to maximize the performance of the rubber composition compared to Comparative Example 5 and further using a softening agent having a PCA content of less than 3% by weight, which is excellent in abrasion performance or fuel efficiency performance. It is possible to obtain a tire tread rubber composition capable of simultaneously improving wear performance, fuel efficiency, braking performance and steering stability.

As described in detail above, styrene-butadiene rubber and butadiene rubber, which are prepared by solution polymerization as a raw material rubber and satisfy specific properties, use an optimal filler and a silane coupling agent, and have a PCA content in an international regulatory level. By using the emulsifier that satisfies this, it is possible to obtain a tread rubber composition excellent in not only excellent adjustment stability performance and low fuel consumption performance, but also wear and braking performance.

Claims (4)

30-50 parts by weight of a solution-polymerized styrene-butadiene rubber A having a styrene content of 15 to 30%, a vinyl content of 60% or more, a glass transition temperature of -27 to -30 ° C, and a molecular weight distribution of 1.3 to 3.0; 30-50 parts by weight of a solution-polymerized styrene-butadiene rubber B having a styrene content of 35 to 50%, a vinyl content of 40% or more, a glass transition temperature of -29 to -32 ° C, and a molecular weight distribution of 2.3 to 4.0; And 100 parts by weight of raw material rubber including 10 to 30 parts by weight of butadiene rubber (BR), 60 to 90 parts by weight of silica, 15 to 50 parts by weight of softener and 10 to 20 parts by weight of silane coupling agent, based on the weight of silica, wherein the softener is benzo (a) pyrene, benzo (b) pyrene, benzo (a PCA (Poly Cyclic Aromatic) Components Including Anthracene, Chrysene, Benzo (a) Floranthene, Benzo (j) Floranthene, Benzo (k) Floranthene, Dibenzo (a, h) Anthracene For tire treads for passenger cars having a total content of less than 3% by weight, a kinematic viscosity of 95, an aromatic component of 15-25% by weight, a naphthenic component of 27-37% and a paraffinic component of 38-58% by weight. Rubber composition. delete delete delete

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