KR20050121354A - Rubber composition for tire of truck or bus - Google Patents

Abstract

The present invention is 100 parts by weight of the raw material rubber consisting of 50 to 80% by weight of natural rubber and 20 to 50% by weight of neodymium butadiene rubber having a sheath content of 98% or more, and the nitrogen adsorption specific surface area of 125 ~ 145mg / g, DBP oil absorption 115 ~ 135cc / 100g To provide a tire tread rubber composition comprising a TINT value of 120 to 140 and 45 to 55 parts by weight of carbon black having an aggregate size distribution (ASD) of 21 to 31, which is equivalent to vulcanized rubber compared to conventional rubber tread rubber compositions. While having physical properties, not only the hysteresis loss is reduced but also the wear resistance is improved.

Description

Tire composition for tire of truck or bus

The present invention relates to a rubber tread rubber composition for trucks / buses, and more particularly, a low carbon glass transition temperature polybutadiene rubber, which is advantageous for wear performance, in addition to natural rubber, and has excellent wear and reinforcement performance. By mixing black, the present invention relates to a rubber composition having improved heat resistance and low fuel consumption as well as wear resistance.

The main characteristics required for truck / bus tires are wear resistance and low heat generation. In general, the wear of the tire is a phenomenon in which the surface of the tread rubber is ground and ground due to the friction force generated between the tire and the road surface. This wear phenomenon is caused by various factors such as the lateral force at the curve, the final force during driving and braking, and the wear of the tire has a great influence on the life and braking performance of the tire. Wear resistance should be excellent.

Conventional techniques for improving abrasion resistance are related to a rubber composition containing a small amount of carbon black having a small particle diameter or a large amount of carbon black having a large particle diameter in a natural rubber having a high molecular weight. Because of this, the physical properties of the rubber composition may be lowered, and carbon black having a large particle size may lower wear resistance or disadvantageous heat generation due to a large amount of use, resulting in lower durability. In addition, as a rubber component, butadiene rubber having a low glass transition temperature can be improved in blending with natural rubber. However, there is a limit to the conventional method of reducing the amount of carbon black or using carbon black having a small particle size. In addition, there have been cases where a problem was solved by applying a new concept of carbon black which can improve low fuel efficiency and field workability while maintaining high wear resistance and high braking resistance, but this also did not significantly improve wear resistance.

Accordingly, the present inventors used a blend of neodymium butadiene rubber having a high cis content and a high linearity and a narrow molecular weight distribution in natural rubber as a raw material rubber while trying to solve the above problems. As a result of applying the carbon black having excellent reinforcement, it was found that not only the wear resistance performance was improved but also the exothermic properties.

In addition, to reduce the phenomenon that the vulcanization time is increased by increasing the butadiene rubber, the appropriate vulcanization time was adjusted by changing the vulcanization system.

Accordingly, an object of the present invention is to provide a tire tread rubber composition that can simultaneously improve the wear resistance performance and heat resistance performance of the tire.

Tire tread rubber composition of the present invention for achieving the above object is a raw material consisting of 50 to 80% by weight of natural rubber and 20 to 50% by weight of neodymium butadiene rubber in a sheath content of 98% or more in the known rubber tread rubber composition. 100 parts by weight of rubber, nitrogen adsorption specific surface area 125 ~ 145mg / g, DBP oil absorption 115 ~ 135cc / 100g, TINT value 120 ~ 140 and ASD (aggregate size distribution) 21 ~ 31 45 ~ 55 parts by weight It is characterized by that.

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

In the rubber composition for tire tread of the present invention, the raw material rubber is natural rubber and neodymium butadiene rubber, and neodymium butadiene rubber means butadiene rubber using a neodymium (Nd) catalyst as a polymerization catalyst during butadiene rubber polymerization.

Neodymium butadiene rubber used in the present invention is a butadiene rubber having a cis content of 98% or more, a low glass transition temperature of -108 to -110 ° C, and a molecular weight distribution of 2.1 to 3.1. It serves to improve the wear characteristics.

It is preferable to use neodymium butadiene rubber which plays such a role so as to be 20 to 50% by weight in the raw material rubber. It is disadvantageous in processing and may cause problems such as deterioration of properties and deterioration of chip cut performance.

In addition to such neodymium butadiene rubber, the raw material rubber in the rubber composition for tire tread of the present invention includes natural rubber.

The rubber mixed with neodymium butadiene rubber may contribute to the improvement of crack and heat resistance performance compared to other synthetic rubbers. This is particularly desirable for applying the rubber composition of the present invention to tires for truck buses.

In addition to the raw material rubber of such composition, the tire tread rubber of the present invention includes conventional compounding agents. Among them, carbon black added as a reinforcing agent has a nitrogen adsorption specific surface area of 125 to 145 mg / g and a DBP oil absorption of 115 to 135cc / 100g, having a TINT value of 120 to 140 and having an ASD (aggregate size distribution) of 21 to 31, which, together with the neodymium butadiene rubber, serves to improve wear characteristics and reduce hysteresis.

If carbon black is a carbon black, the nitrogen adsorption specific surface area usually used for tread rubber composition is 115 to 135 mg / g, DBP oil absorption is 125 to 145, TINT value is 110 to 130, and ASD (aggregate size distribution) is 54 to 64. When using the neodymium butadiene rubber as a raw material rubber, the effect does not reach the intended degree.

In the present invention, the content of carbon black is 45 to 55 parts by weight based on 100 parts by weight of the raw material rubber. If the content is less than 45 parts by weight based on 100 parts by weight of the raw material rubber, the wear resistance is lowered. It may increase, resulting in poor workability and too high heat generation.

On the other hand, in the present invention, in consideration of the phenomenon that the vulcanization time is increased according to the increase in the amount of synthetic rubber used, sulfur treated with oil, preferably sulfur treated with 1% naphthenic oil as 100% by weight of raw rubber 1 It is preferable to use in 2 weight part-2, and it is preferable to use an accelerator at 0.9-1.5 weight part with respect to 100 weight part of raw material rubbers.

In addition, a compounding agent such as zinc oxide, stearic acid, or the like, which is usually added in a rubber composition for tire tread, may be included, but is not particularly limited thereto.

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

In the following, the physical properties were measured by the following method.

1) Abrasion resistance index: Tested with a rambon abrasion tester, the larger the index indicates that the wear resistance is improved.

2) Resilience: Tested by the Ueshima impact resilience tester, the higher the value, the lower the fever.

3) HYSTERESIS LOSS: Measured by RHEOMETRICS DYNAMIC SPECTROMETER, the larger the index value, the lower the exotherm.

Comparative Example 1

As shown in Table 1 below, nitrogen is generally used as an additive of a rubber composition based on 80 parts by weight of natural rubber and 100 parts by weight of raw material rubber consisting of 20 parts by weight of nickel butadiene rubber (Ni-BR) using a nickel catalyst as a polybutadiene rubber. Adsorption specific surface area 115 ~ 135mg / g, DBP oil absorption 125 ~ 145, TINT value 110 ~ 130, ASD (aggregate size distribution) 54 ~ 64 45 ~ 55 parts by weight, zinc oxide, 3.5 parts by weight, stearic acid A rubber composition was prepared by mixing 2.5 parts by weight, 1.2 parts by weight of sulfur treated with 1% naphthene oil, and 1.1 parts by weight of accelerator to prepare a rubber composition, which was then vulcanized at 150 ° C. to prepare a rubber specimen.

Comparative Example 2

Nitrogen adsorption specific surface area 125 ~ 145mg / g, DBP oil absorption 115 ~ 135cc / 100g, TINT value 120 ~ 140, except that 45 ~ 55 parts by weight of carbon black with ASD (aggregate size distribution) 21 ~ 31 Was prepared in the same manner as in Comparative Example 1.

Comparative Example 3

Specimen was prepared in the same manner as in Comparative Example 1 except that 70 parts by weight of natural rubber and 30 parts by weight of neodymium butadiene rubber (Nd-BR) using a neodymium catalyst were used as polybutadiene rubber.

<Example 1>

Specimens were prepared in the same manner as in Comparative Example 2 except that 80 parts by weight of natural rubber and 20 parts by weight of Nd-BR were used as polybutadiene rubber and 1.4 parts by weight of sulfur was used as the raw material rubber.

<Example 2>

Nitrogen adsorption specific surface area 125 ~ 145mg / g, DBP oil absorption 115 ~ 135cc / 100g, TINT value 120 ~ 140, ASD (aggregate size distribution) 21 ~ 31 52 parts by weight carbon black 1.4 parts by weight Except that except that the specimen was prepared in the same manner as in Comparative Example 3.

Specific composition and physical property evaluation results are shown in Table 1 below.

Item Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Natural Rubber (NR) 80 80 70 80 70 Synthetic rubber (Ni-BR) ¹ 20 20 - - - Synthetic Rubber (Nd-BR) ² - - 30 20 30 Carbon Black A ³ 52 - 52 - - Carbon Black B ⁴ - 52 - 52 52 Zinc oxide 3.5 3.5 3.5 3.5 3.5 Stearic acid 2.5 2.5 2.5 2.5 2.5 brimstone 1.2 1.2 1.2 1.4 1.4 accelerant 1.1 1.1 1.1 1.1 1.1 Hardness 66 66 66 66 67 100% Mod. 27 27 30 28 30 Wear Resistance Index 100 107 112 115 125 Resilience Index 50.5 51.0 51.3 51.5 53.0 Hysteresis Ross ⁵ 100 104 107 111 116 1. Synthetic rubber (Ni-BR): cis content 96%, glass transition temperature is -103 ~ -106 ℃, molecular weight distribution is 5.0 ~ 6.02. Synthetic rubber (Nd-BR): cis content more than 98%, glass transition temperature is -108 ~ -110 ℃, molecular weight distribution is 2.1 ~ 3.13. Carbon Black A: Nitrogen adsorption specific surface area is 115 ~ 135mg / g, DBP oil absorption 125 ~ 145, TINT value 110 ~ 130, ASD (aggregate size distribution) 54 ~ 644. Carbon Black B: Nitrogen adsorption specific surface area is 125 ~ 145mg / g, DBP oil absorption is 115 ~ 135 cc / 100g, TINT value is 120 ~ 140 and ASD is 21 ~ 315. Hysteresis Loss: 0.5% strain, 10Hz, Temp. 60 degreeC tan δ was measured by sweep.

From the results of Table 1, when carbon black B was added to butadiene rubber (Nd-BR) using a neodymium catalyst, and 1.4 parts by weight of sulfur and 1.1 parts by weight of accelerator were added, equivalent vulcanizability was compared with conventional rubber compositions. It can be seen that not only does hysteresis loss decrease, but also excellent wear resistance is obtained.

As described in detail above, the rubber composition using sharp carbon black as compared to the carbon black that is commonly used while using natural rubber and neodymium butadiene rubber as a raw material rubber according to the present invention is of the same level as the rubber composition for tire treads While having vulcanization properties, hysteresis loss can be reduced and wear resistance can be improved.

Claims (3)

In a known rubber tread rubber composition, 100 parts by weight of raw material rubber consisting of 50 to 80% by weight of natural rubber and 20 to 50% by weight of neodymium butadiene rubber having a sheath content of 98% or more, and a nitrogen adsorption specific surface area of 125 to 145 mg / g and a DBP oil absorption of 115 to 135 cc / 100 g, and a TINT value. The tread rubber composition for truck buses, characterized in that it comprises 120 to 140 and 45 to 55 parts by weight of carbon black having an aggregate size distribution (ASD) of 21 to 31. The tire tread rubber composition for a truck bus according to claim 1, wherein the neodymium butadiene rubber has a glass transition temperature of -108 to -110 ° C, a cis content of 98% or more, and a molecular weight distribution of 2.1 to 3.1. The tire for a truck bus according to claim 1, comprising 1-2 parts by weight of sulfur treated with 1% naphthene oil and 0.9 to 1.5 parts by weight of Nt-butyl-2-benzothiazyl-sulfenamide as an accelerator. Tread rubber composition.