KR20040002185A - Polycyclic aromatics free tread compound of truck-bus radial tire used in Deep tread - Google Patents

Abstract

PURPOSE: Provided is a tread rubber composition of truck and bus radial tires for a deep tread, which contains small polycyclic aromatics and is excellent in heat resistance and abrasion property. CONSTITUTION: The tread rubber composition contains 100pts.wt. of a raw rubber comprising 60-70pts.wt. of a natural rubber and 30-40pts.wt. of a butadiene rubber, 55-60pts.wt. of carbon black, and 4-7pts.wt. of paraffin oil containing less than 3wt% of the polycyclic aromatics. The tires produced by using the tread rubber composition are excellent in performance and friendly to environment.

Description

Polycyclic aromatics free tread compound of truck-bus radial tire used in Deep tread}

The present invention relates to tread rubber compositions of truck and bus radial tires for deep treads, and more particularly to tread rubber compositions of truck and bus radial tires for deep treads using paraffin oils with low polycyclic aromatics content. It is about.

The increase in automobiles, an indispensable necessity in modern society, has brought various conveniences to human life. However, as the number of automobiles increases, many problems such as human loss due to traffic accidents, pollution and environmental problems, deepening of petroleum energy, and transportation problems are emerging. In particular, the problem of environmental pollution that is closely related to life must be solved. Remains a challenge to do. To this end, regulations on harmful substances are being tightened on raw tire parts, which are an important part of automobile parts.

The process oil is used for the purpose of making it easy to process rubber | gum of a tire raw material, and a volume increase. Generally, in the tire industry, aromatic oils having good affinity with rubber and good finished product performance, and having high poly cyclic aromatics (PCA) content are widely used. However, several studies have reported that oil tests on rat skin according to PCA content result in skin cancer when the PCA content is above 3%. The European Union recommends that carcinogens be reduced or replaced when there is a technical alternative. And the Swedish National Chemicals Inspectorate (KEMI) report published in Sweden in 1994 raised interest in the use of oils with high PCA content in tire compositions.

Accordingly, the European Union's Dangerous Substances Commission mandates that oils containing 3% PCA content are carcinogenic by IP 346 DMSO Extraction and that carcinogen labels and texts are also sold on the oil and its products. . Therefore, the tire industry was also required to develop tires with high performance and less than 3% PCA content.

Thus, in the present invention, instead of the aromatic oil having a PCA content of 13 wt% or more, conventional treads for deep tread having excellent heat resistance and wear characteristics using paraffinic oil having a PCA content of less than 3 wt%. An object is to provide a tread rubber composition for truck and bus radial tires.

The present invention relates to 55-60 parts by weight of carbon black and polycyclic aromatics with less than 3 wt% of paraffinic oil, based on 100 parts by weight of raw rubber containing 60-70 parts by weight of natural rubber and 30-40 parts by weight of butadiene rubber. It is characterized by including 7 parts by weight.

In the present invention, when using less than 4 parts by weight of paraffinic oil with respect to 100 parts by weight of the raw material rubber, there is a problem that the fairness when the rubber composition is blended, when using more than 7 parts by weight of excess oil is the physical properties of the rubber Since it may reduce, it is preferable to include 4-7 weight part of paraffinic oil with respect to 100 weight part of raw material rubbers in this invention.

Table 1 compares the characteristics of aromatic oils and paraffin oils in process oils.

Table 1. Comparison of properties of aromatic oils and paraffin oils

division Aromatic oils Paraffin oil PCA, wt% 13.6 1.0 Ca / Cp / Cn 41/24/35 5/62/33 importance 1.1095 0.8705 Kinematic viscosity (98.9 ℃, cSt) 21.5 11.5 Aniline point (℃) 43.5 106.5

The PCA, wt% represents the PCA content in the oil.

The Ca / Cp / Cn represents Aromatic, Paraffine, Naphthene oil content.

The aniline point (° C.) is a numerical value representing polarity, and is measured for compatibility with aniline, which is a typical polar material, and becomes a management standard for workability and affinity with rubber.

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

(Comparative Example)

As shown in the mixing ratios shown in Table 2, the present invention is 57 parts by weight of carbon black, 6 parts by weight of aromatic oil as a process oil, and 1.5 parts by weight of stearic acid, based on 100 parts by weight of raw rubber containing natural rubber and butadiene rubber at 6: 4 , 4 parts by weight of zinc, 4.5 parts by weight of antioxidant, 2.2 parts by weight of sulfur, 0.9 parts by weight of vulcanization accelerator, 0.2 parts by weight of a retarder, and mixed with the rubber specimens were prepared using a Banbury mixer.

(Example)

A rubber specimen was prepared using the same composition, composition ratio, and method as in Comparative Example, except that 6 parts by weight of paraffin oil was used instead of 6 parts by weight of aromatic oil as a process oil.

Table 2. Tread rubber compositions for truck buses of Examples and Comparative Examples (unit: parts by weight)

division Comparative example Example Natural rubber 60 60 BR rubber 40 40 Carbon black 57 57 Process oil Aromatic oils 6 - Paraffin oil - 6 Stearic acid 1.5 1.5 Zincification 4 4 Anti-aging 4.5 4.5 brimstone 2.2 2.2 Vulcanization accelerator 0.9 0.9 Retardant 0.2 0.2

<Test Example>

The rubber specimens of Comparative Examples and Examples were measured for physical properties according to ASTM-related regulations, and the results are shown in Table 3 below.

Table 3. Results of Measurement of Physical Properties of Comparative Examples and Examples

division Comparative example Example Viscosity 100 ℃ 90 92 Tensile Properties Hardness, Shore A method 67 67 300% modulus, kg / cm ² 133 133 Tensile strength, kg / cm ² 222 220 Elongation,% 466 463 Exothermic performance Temperature rise, ℃ 32 28 Blow out Breaking time, min 5.8 6.0 Wear performance Wear, g 0.016 0.014

As shown in Table 3, the physical property measurement results are as follows.

First, the exothermic performance shows excellent properties as the temperature rises, the embodiment according to the present invention can be seen that the properties are improved than the comparative example.

Second, the blow out shows excellent characteristics as the break time is longer, and the embodiment according to the present invention can be seen that the characteristics are improved than the comparative example.

Third, the wear performance shows excellent characteristics as the generation amount is smaller, and the embodiment according to the present invention can be seen that the characteristics are improved than the comparative example.

As shown in Comparative Examples and Examples above, in the tread rubber composition of truck and bus radial tires, paraffinic oil having a PCA content of less than 3 wt% is substituted for aromatic oil having a PCA content of 13 wt% or more. By using it, the heat resistance (heating performance, blow out) and abrasion performance are improved while maintaining the same level as the existing technology, thereby making it possible to manufacture tires having excellent performance and environmentally friendly.

Claims (1)

In the tread rubber composition of truck and bus radial tires for deep tread, 55-60 parts by weight of carbon black and 4-7 parts by weight of paraffinic oil having a polycyclic aromatic content of less than 3% by weight based on 100 parts by weight of raw rubber containing 60-70 parts by weight of natural rubber and 30-40 parts by weight of butadiene rubber Tread rubber composition for truck and bus radial tires for deep treads, including