KR20020076626A - Tread Composition of Radial Tire for Truck and Bus with High Anti-Cutting and Anti-Chipping Resistance by means of Using Low Toxic Softner - Google Patents

Abstract

PURPOSE: Provided is a radial tire tread rubber composition for trucks and buses by using a low toxic softener, which is excellent in blend, extrusion processability, and cutting resistance/chipping resistance. CONSTITUTION: The radial tire tread rubber composition for trucks and buses, which run on unpaved roads mainly, contains 0.5-5.0wt%(based on a raw rubber) of the low toxic softener containing about 3% of polycyclic aromatics(PCA), wherein the low toxic softener is a tyrex-20 oil being friendly to environment and excellent in blend and extrusion properties.

Description

Tread Composition of Radial Tire for Truck and Bus with High Anti-Cutting and Anti-Chipping Resistance by means of Using Low Toxic Softner}

The present invention is a radial tire tread rubber composition for truck buses, and more particularly, softeners blended in the tread rubber composition are replaced with materials that have little harm to the human body from existing toxic materials, and at the same time, the conventional softeners The present invention relates to a tread rubber composition for truck buses configured to be maintained at an equivalent level or higher.

Tread rubber of pneumatic tires, mainly used for truck buses on unpaved roads, is made of natural carbon and synthetic rubber using the appropriate carbon black, anti-aging agent, softener and vulcanizing agent. In order to minimize chipping due to cutting or rough road surfaces, the modulus is usually designed to be 100 kg / cm 2 or less.

There are many types of softeners used for smooth compounding and extrusion processes, and generally, aromatic oils are known to achieve optimum physical properties and smooth processability. However, in a recent Swedish study, animal tests using different oils containing polycyclic aromatics (PCA) have shown that oils with a PCA content above 3% are more likely to cause skin cancer. Reported. The European Tire Manufacturers Association (BLIC) accepted the above test results and took measures to prepare for them.The Swedish government established specific usage regulations.In 2002, the oil manufacturer and the products using the oil contained more than 3% of PCA. The company decided to legalize the sale of toxic carcinogenic labels.

In addition, conventional oils, including paraffin oils, are unstable in the formulation and extrusion process even if the PCA content is within the regulated level, making it difficult to achieve optimal performance of the product. The discovery of matter is a very urgent task in the present situation.

The inventors of the present invention have been in search of a substitute material for overcoming the problems of the prior art as described above by replacing the existing oil with an oil having a good compounding and extrusion processability while the PCA content is within 3%. The present invention was completed by confirming that a result that satisfies both requirements can be obtained.

Therefore, an object of the present invention is to provide a novel truck bus radial tire tread rubber composition containing less than 3% PCA, and at the same time excellent in blending and extrusion processability and cutting / chipping resistance.

The present invention is primarily a radial tire tread rubber composition for truck buses traveling on a dirt road, and is characterized by adding a softener containing PCA within 3%.

Since the tread rubber composition of the present invention contains PCA within 3%, it is environmentally friendly, and is excellent in blending and extrusion processability and cutting / chipping resistance.

The low PCA-containing softener is preferably Tyrex-20 oil. The oil is environmentally friendly, with an average PCA content of 1.4% and less than 3%. In addition, conventional aromatic oils have a low aromatic content of about 5%, which is compatible with rubber, whereas Tyrex-20 oils have a high content of about 24%. It contains about 62% in -2 oil, while the Tyrex-20 oil has a low property of about 34% and has excellent physical properties in blending and extrusion performance.

Although the amount of the low PCA-containing softener is not particularly limited, it is preferable to add 0.5 to 5.0% by weight of the raw material rubber when preparing the tread rubber composition to improve the compounding and extrusion performance.

Hereinafter, the contents of the present invention will be described in detail with reference to the following examples, but the scope of the present invention is not limited to these examples.

Comparative Example 1

The tread rubber composition of truck tire radial tires traveling more than 80% on unpaved roads was manufactured according to a known method using raw materials applied to ordinary tires, and as a softener, aromatic # 2 (Aromatic # 2 (PCA) Content: 13.6%), Michang Petroleum Co., Ltd.). The composition and physical properties of the blended raw materials are shown in Table 1.

Comparative Example 2

The tread rubber composition of truck tire radial tires traveling more than 50% on unpaved roads was manufactured according to a known method using raw materials applied to ordinary tires, and as a softener, aromatic # 2 (Aromatic # 2 (PCA) was used. Content: 13.6%), Michang Petroleum Co., Ltd.). The composition and physical properties of the blended raw materials are shown in Table 2.

<Example 1>

The tread rubber composition of truck tire radial tires traveling more than 80% on unpaved roads was manufactured according to a known method using raw materials applied to ordinary tires, and as a softener, Tyrex-20 oil (Tyrex-20 ( PCA content: 1.4%), British Petroleum, UK). Composition and physical properties of the blended raw materials are as shown in Table 1.

<Example 2>

The tread rubber composition of truck tire radial tires traveling more than 50% on unpaved roads was manufactured according to a known method using raw materials applied to ordinary tires, and as a softener, Tyrex-20 oil (Tyrex-20 ( PCA content: 1.4%), British Petroleum, UK). Composition and physical properties of the blended raw materials are as shown in Table 2.

<Test Example>

The wear resistance and cutting / chipping performance obtained from the durability and actual vehicle test results for the 11.00R20 standard tires manufactured using the formulations obtained through the Comparative Examples and Examples are shown in Tables 3 to 4 below.

<Table 1> Tread rubber compositions and physical properties for tires running over 80% on unpaved roads

Item Comparative Example 1 Example 1 Natural rubber carbon black inorganic reinforcing agent process oil (aromatic-2) process oil (Tirex-20) stearic acid zinc anti-aging agent Sulfur / vulcanization residue 100 100 50 50 10 10 4 - - 4 2 2 5 5 6.5 6.5 2 / 0.6 2 / 0.6 Compound dispersion 93% 92% Rubber viscosity (100 ℃) 59.8 60.0 Extrusion Tread Shrinkage 12% 11% Tensile Properties (Initial / Aging) Hardness, shore A 61/67 61/67 300% modulus, kg / ㎠ 84/119 86/117 Tensile strength, kg / ㎠ 246/221 260/232 Elongation,% 637/529 633/502 Exothermic performance Temperature rise, ℃ 32.9 31.2 Wear performance Pico method, g 0.0463 0.0449 Cutting / Chipping Resistance, (Monsanto Method, g) 2.786 2.6065

<Table 2> Tread Rubber Compositions and Properties for Tires

Item Comparative Example 2 Example 2 Natural rubber styrene butadiene rubber carbon black (N220) process oil (aromatic-2) process oil (Tirex-20) stearic acid zinc aging inhibitor sulfur / vulcanization residue 70 70 30 30 52 52 3 - - 3 One One 5 5 5 5 1.8 / 0.75 1.8 / 0.75 Compound dispersion 95% 95% Rubber viscosity (100 ℃) 56.8 56.5 Extrusion Tread Shrinkage 11.5% 11.7% Tensile Properties (Initial / Aging) Hardness, shore A 64/69 64/68 300% modulus, kg / ㎠ 94/127 97/124 Tensile strength, kg / ㎠ 274/216 270/222 Elongation,% 630/475 633/492 Exothermic performance Temperature rise, ℃ 34.5 34.1 Wear performance Pico method, g 0.0355 0.0314 Cutting / Chipping Resistance, (Monsanto Method, g) 1.5825 1.5363

<Table 3> Tire Performance with Tread Rubber Composition for Running Tires

Item Comparative Example 1 Example 1 Durability Results (ECER-54) 58hr05min Trap Belt Burst 60hr49min Trap Belt Burst 70hr 42min Trap Belt Burst 72hr 10min Tread Belt Burst Abrasion Resistance Index (km / TREAD mm) 1,249 1,269 Cutting / Chipping Index (Point / TREAD) 18 13

* The longer the durability, the higher the wear resistance index, and the smaller the cutting / chipping index, the better the performance.

<Table 4> Tire performance made of tread rubber composition for running tires over 50% of unpaved road

Item Comparative Example 2 Example 2 Durability Results (ECER-54) 61hr 12min Tread Belt Burst 62hr27min Tread Belt Burst 65hr21minTrading Belt Burst63hr15minTrading Belt Burst Abrasion Resistance Index (km / TREAD mm) 2,287 2,451 Cutting / Chipping Index (Point / TREAD) 11 8

* The longer the durability, the higher the wear index, and the smaller the cutting / chipping index, the better the performance.

When the rubber composition according to the present invention is applied to tire treads, the abrasion resistance, cutting resistance, chipping resistance and chipping performance and durability are improved while maintaining the compounding processability and the extrusion processability at the same level or higher than the current levels, as well as 3% of harmful PCA. It is contained within the environmentally friendly advantages.

Claims (3)

Radial tire tread rubber composition for truck buses, mainly for driving on a dirt road, wherein the added softener contains less than 3% of the PCA content. The radial tire tread rubber composition for a truck bus according to claim 1, wherein the softener comprises Tyrex-20 oil. 3. The radial tire tread rubber composition according to claim 1 or 2, wherein the softener is added in an amount of 0.5 to 5.0 wt%.