KR100635799B1 - Tread rubber composition for truck/bus tire - Google Patents

Abstract

Provided is a tire tread rubber composition for a truck or a bus which is excellent in abrasion resistance and is improved in wet traction by using a carbon black showing specific colloidal characteristics. The tire tread rubber composition comprises 40-60 parts by weight of the carbon black which has an N2 adsorption specific surface area of 125-145 mg/g, a DBP oil absorption of 115-135 cc/100 g and a TINT value of 120-140, based on 100 parts by weight of a rubber material which comprises 60 wt% of a natural rubber, 10-30 wt% of a high-cis neodymium butadiene rubber, and 10-30 wt% of a solution polymerization styrene-butadiene rubber.

Description

Tread rubber composition for truck / bus tire}

The present invention relates to a rubber composition for tire treads for trucks / buses, and more particularly, to high-cis niobium-butadiene (Butadiene) rubber with low glass transition temperature, which is advantageous for abrasion performance in a certain ratio of natural rubber. Improved wear, braking, and durability performance by using solution polymerization type styrene-butadiene rubber as a raw material rubber and carbon black satisfying specific colloidal properties. To a tread rubber composition of a truck / bus tire.

In general, truck / bus tires have mainly used natural rubbers having high heat resistance and high molecular weight and high elasticity due to high load durability. The use of carbon black with small particle size and excellent reinforcement performance in such natural rubber can improve abrasion resistance.However, the use of carbon black with small particle size increases heat generation due to friction between carbon blacks, resulting in disadvantageous heat generation and durability. There are disadvantages.

In order to remove the limited performance of the carbon black and improve the wear resistance, butadiene rubber having a low glass transition temperature is required. In particular, Japanese Patent Publication No. 1995-118443 discloses butadiene rubber having high linearity and narrow molecular weight distribution and carbon black having specific colloidal properties to improve wear resistance and heat resistance. Used.

However, the wear resistance can be improved by using butadiene rubber, which is a synthetic rubber. However, the mechanical strength is lower than that of natural rubber, which is disadvantageous in terms of durability. Braking performance is reduced, in particular, the disadvantage is that the wet performance (Wet Traction) on the wet road surface is disadvantageous.

Accordingly, the present inventors have been studying to solve various problems in manufacturing the tread rubber composition of a conventional truck / bus tire as described above, and as a raw material rubber, natural rubber and high-cis neodymium butadiene Rubber and solution-polymerized Styrene-Butadiene rubber are mixed in an appropriate ratio, and carbon black that satisfies specific colloidal properties is used. It was found that the braking performance can be improved at the same time to complete the present invention.

Accordingly, an object of the present invention is to provide a tread rubber composition of a truck / bus tire having excellent wear resistance and improved braking performance on wet road surfaces.

The rubber composition for the tread of the truck / bus tire of the present invention for achieving the object of the present invention as described above is 60% by weight of natural rubber, 10-30% by weight of high-cis niodymium butadiene rubber, and solution polymerization styrene- Carbon black 40 having a nitrogen adsorption specific surface area of 125 to 145 mg / g, a DBP oil absorption of 115 to 135cc / 100g, and a TINT value of 120 to 140 with respect to 100 parts by weight of the raw material rubber containing 10 to 30% by weight of butadiene rubber. Characterized in that it comprises ~ 60 parts by weight.

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

The present invention relates to a rubber composition for a tread of a bus / truck tire comprising carbon black and other additives satisfying specific colloidal properties in raw rubber including natural rubber and other synthetic rubbers.

The raw material rubber of the present invention includes natural rubber, high-cis niodymium butadiene rubber, and solution polymerized styrene-butadiene rubber.

The natural rubber is not particularly limited as long as it is used in a conventional tire tread rubber composition, natural rubber is determined to use 60% by weight of the total raw rubber.

In addition, as the butadiene rubber, niobium butadiene (Nd-BR) rubber is particularly used. Butadiene rubber can use several catalysts according to the manufacturing process. Butadiene rubber prepared using a niobium catalyst has a cis content (97 to 99%) than butadiene rubber prepared using a cobalt (Co) or nickel (Ni) catalyst. Its high, high molecular weight, low degree of branching and high linearity make it more advantageous in terms of wear resistance and heat generation. Therefore, in the present invention, the niobium-butadiene rubber having a high cis content as described above is used in 10 to 30% by weight of the total raw rubber.

In addition, the solution-polymerized styrene-butadiene (S-SBR) rubber used for braking performance is characterized in that the styrene content of 13-17%, vinyl content of 28-33%, other high styrene content and low vinyl content It has better heat generation and physical properties than styrene-butadiene rubber. Such solution-polymerized styrene-butadiene rubber is included in 10 to 30% by weight of the total raw rubber.

However, it is advantageous in terms of maintaining braking performance that the sum of the niobium-butadiene rubber and the solution-polymerized styrene-butadiene rubber does not exceed 40 parts by weight of the total raw rubber.

Carbon black that satisfies specific colloidal properties suitable for maintaining abrasion resistance and heat generation performance is used in the raw material rubber compounding ratio as described above. The carbon black has a nitrogen adsorption specific surface area of 125 to 145 mg / g and a DBP oil absorption of 115 It is ˜135 cc / 100g and the TINT value is 120 to 140. In the present invention, it is preferable to use 40 to 60 parts by weight of carbon black with respect to 100 parts by weight of the raw material rubber in order to express the wear resistance and heat resistance characteristics as described above.

In addition to the above-described composition, the rubber composition of the present invention can add other additives included in conventional rubber compositions such as processed oil, sulfur, vulcanization accelerator, and antioxidant.

Hereinafter, the present invention will be described in detail with reference to the following Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1 and Comparative Examples 1 and 2

Next, the tread rubber compositions of Examples and Comparative Examples were prepared according to a method of preparing a general tire rubber composition using the composition shown in Table 1 below. Example 1 uses 100 parts by weight of raw material rubber containing 20% by weight of niobium-butadiene rubber and solution-polymerized styrene-butadiene rubber in 60% by weight of natural rubber, Comparative Example 1 is a raw material rubber containing only natural rubber 100 parts by weight was used, and Comparative Example 2 used 100 parts by weight of the raw material rubber containing 60% by weight of natural rubber and 40% by weight of niodymium-butadiene rubber.

Compounding agent (content: parts by weight) Comparative Example 1 Comparative Example 2 Example Raw material rubber (wt%) Natural rubber (NR) 100 60 60 Niodymium-Butadiene Rubber (Nd-BR) ⁽¹⁾ - 40 20 Solution Polymerized Styrene-Butadiene Rubber (Sol-SBR) ⁽²⁾ - - 20 Carbon Black ⁽³⁾ 55 55 55 zinc oxide 5 5 5 Stearic acid 2 2 2 Process oil 3 3 3 brimstone 1.6 1.6 1.6 Vulcanization accelerator 1.2 1.2 1.2 (1) Niodymium-butadiene rubber: Sheath content 97-99%, glass transition temperature -103-110 degreeC, molecular weight distribution 2.0-3.5. (2) Solution polymerization Styrene-butadiene rubber: Styrene content 13-17%, Vinyl content 28-33%, Glass transition temperature -60 ~ -70 ℃. (3) Carbon black: Nitrogen adsorption specific surface area 125-145 mg / g, DBP oil absorption 115-135cc / 100g, TINT value 120-140.

The physical properties of the rubber composition obtained from the above and Examples and Comparative Examples were evaluated as follows, exothermic evaluation was carried out according to ASTM (D623) using a Flexometer, and durability evaluation was made in the tire 12R22.5 standard for trucks as follows. Evaluation was performed as shown in Table 2 below.

(1) The measurement of tensile properties was carried out with a tensile tester manufactured by Instron by cutting the specimen into dumbbells. 100% modulus refers to the stress acting on a specimen when it is stretched 100%. Tensile strength represents the maximum stress value until the rubber specimen breaks. In addition, hardness is measured with the Shore A type.

(2) The durability was measured at 80KPH speed under 100% load condition and expressed in relative index based on the value of Comparative Example 1 as 100, indicating that the higher the value, the better the durability performance.

(3) Wear resistance refers to Lambbourn abrasion, which represents the loss of rubber worn by rotating at a sliding ratio of 25% and a load of 1.5 kg at room temperature. The relative index is based on 100 in Comparative Example 1. The larger the value, the better the wear performance.

(4) The braking performance on the wet road surface was measured by using a viscoelasticity measuring instrument, the tanδ value of 0 ℃, expressed as a relative index based on the value of Comparative Example 1 as 100, indicating that the greater the value the better the braking performance.

Compounding agent Comparative Example 1 Comparative Example 2 Example 1 Shore A 68 68 67 100% modulus 31 29 28 Tensile Strength (MPa) 326 283 286 Heat resistance (℃) 145 ℃ 156 ℃ 157 ℃ durability 100 100 102 Wear resistance 100 110 118 Wet Traction 100 82 102

As can be seen from the results of Table 2, Example 1 prepared from the composition as the present invention is significantly improved wear resistance compared to Comparative Examples 1 and 2, the braking performance is also secured at an equivalent level or higher than Comparative Example 1 It can be seen that, even in Comparative Example 2 compared to Comparative Example 1, the wear performance is improved, but the braking performance is very poor.

As described in detail above, when the carbon black that satisfies specific colloidal properties is used as a reinforcing agent in the raw material rubber including natural rubber, niobium-butadiene rubber and solution-polymerized styrene-butadiene rubber as the present invention, In addition to excellent performance, braking performance on wet roads has an improved effect.

Claims (4)

Nitrogen adsorption specific surface area is 125-145 mg with respect to 100 weight part of raw material rubber which consists of 60 weight% of natural rubbers, 10-30 weight% of high-cis niodymium butadiene rubbers, and 10-30 weight% of solution polymerization styrene-butadiene rubber. A rubber composition for a tread of a truck / bus tire comprising 40 to 60 parts by weight of carbon black / g, having a DBP oil absorption of 115 to 135 cc / 100 g and a TINT value of 120 to 140. The rubber composition for tread of a truck / bus tire according to claim 1, wherein the sum of the high-cis niobium-butadiene rubber and the solution-polymerized styrene-butadiene rubber does not exceed 40% by weight in the total raw rubber. . The bus / truck according to claim 1, wherein the high-cis niobium-butadiene rubber has a cis content of 97 to 99%, a molecular weight distribution of 2.0 to 3.5, and a glass transition temperature of -103 to -110 ° C. Rubber composition for the tread of the tire. The bus / truck according to claim 1, wherein the solution-polymerized styrene-butadiene rubber has a styrene content of 13 to 17%, a vinyl content of 28 to 33%, and a glass transition temperature of -60 to -70 ° C. Rubber composition for tread of tires.