KR100274906B1 - A rubber composition of steel cord for radial tire - Google Patents

Abstract

PURPOSE: A rubber composition for steel cord of the radial tire is provided for contacting and adhering the rubber and the steel cord to improve ageing-resistance and higher strength even low expansion condition, and prevent crack due to difference of stress between rubber and steel cord. CONSTITUTION: The rubber composition for adhering steel cord and the radial tire comprises 5-80 parts by weight of the double phases filler reformed by contacting silanol component onto surface of the carbon black in terms of 100 parts by weight of the natural rubber; 0.1-3 parts by weight of bis-(3-tri ethoxysilylpropyl)tetrasulfan as the coupling agent, 4-6 weight parts of sulfur as the commercial additive, 10 parts by weight of cobalt naphthenate/resorcinol-formaldehyde hydrazine/hexa methoxy methyl melamine, 2 weight parts of N,N-dicyclohexyl-2-benzothiazole sulfenamide.

Description

Rubber compositions for steel cords of radial tires

The present invention relates to a rubber composition for bonding the rubber of the radial tire and the steel cord. More specifically, by mixing the carbonylated carbon bladder and the ideal filler of silica into the rubber by incorporating the silanol component, which is the main component of silica, into a conventional carbon black used as a rubber reinforcing agent, the rubber has a vulnerable physical property. The present invention relates to a rubber composition which improves the durability of the belt part by increasing the strength to reduce the stress difference in the adhesive surface between the rubber and the steel cord, and on the other hand, by improving the aging resistance.

The belt part of the tire is deteriorated due to fatigue and heat by transferring heat generated by deformation due to repeated bending motion during driving and heat generated by the bending, impact, deformation, etc. generated in the tread and shoulder parts. This is the cause of cracks in the rubber of the belt part and promotes growth.

The belt part of the radial tire mainly uses steel cord as a reinforcing agent to increase the mechanical strength of the tread area. The steel cord used is plated with a material whose main components are copper and zinc to improve adhesion between rubber and steel cord. These plating materials are easily invaded by moisture and salts penetrated from the outside, causing cracks and deterioration of adhesion.

In addition, such a crack and a decrease in adhesion force are further deepened at the bonding interface between the rubber and the steel cord by the stress difference caused by the difference in strength between the rubber and the steel cord, thereby causing a problem in the durability of the tire.

Rubber composition for adhesion of rubber and steel cord should basically have easy processing performance. As vulcanization property, high adhesive strength under all conditions including high strength at low elongation, low elongation, good aging, low heat generation and aging conditions Should be there.

Therefore, as part of improving the durability of radial tires, various methods have been developed and used to improve the aging resistance and fatigue resistance of the rubber composition for bonding the belt rubber to the steel cord. The most widely used method is the so-called high-sulfur system. to be.

The system improves the initial adhesion by adding a large amount of sulfur to help adhesion by working with the copper component of the steel cord plating, and at the same time increases the strength of the rubber to reduce the stress difference between the rubber and steel cord to prevent the initial cracking but The use of sulfur has disadvantages in the aging resistance of rubbers, in particular in the heat aging resistance, which leads to problems in tire durability.

Cobalt-Resorcinol, Hexamethoxymethylmelamine (Co-RH) System and Cobalt-Hysilica, Resorcinol, Hexamethoxymethylmelamine (Co-HRH) The system has been developed, and the Co-RH system is superior to the Co-HRH system in the initial adhesion, but most of them prefer the Co-HRH system due to its disadvantage in aging resistance. However, in the case of Co-HRH system, due to the use of silica, excessive processing power loss and even dispersion in the rubber, and silica's own interaction is weak, so that the bonding strength with the rubber is weak. Because of this high strength under low elongation conditions and an increase in elongation at break, the stress difference becomes large at the interface between rubber and steel cord, causing stress concentration. There was a problem that the liver stress difference became large.

The present inventors applied Co-HRH system in which silica is mixed to solve the heat-resistant aging problem of the existing high-sulfur system, and the problem of processing performance and low strength under low elongation conditions by using silica, which is the biggest problem of the system, As a result of research to solve the problem, the above problem is solved while maintaining the aging resistance function of the Co-HRH system by using an ideal filler of carbon black and silica modified by incorporating silanol component on the surface of carbon black. This has led to the present invention.

Accordingly, the present invention is to reduce the stress difference between the rubber and the steel cord by reducing the stress difference between the rubber and the steel cord has a high strength under low elongation conditions to prevent the cracking at the interface, improved heat aging resistance and fatigue resistance And to provide a rubber composition that improves the adhesion in the overall aging conditions, including heat aging conditions and easy to blend and process.

The present invention is a rubber composition for bonding rubber and steel cord, 5 to 80 parts by weight of an ideal filler of carbon black and silica modified by grafting silanol component to the surface of carbon black with respect to 100 parts by weight of natural rubber, coupling agent 0.1 to 3 parts by weight of bis- (3-triethoxysilylpropyl) tetra-sulfane, 4 to 6 parts by weight of sulfur, which is a common additive, and cobalt naphthenate / resosinol-formaldehyde / hexamethoxy as binder It relates to a rubber composition for the adhesion of rubber and steel cord of a radial tire, characterized in that 10 parts by weight of methyl melamine, 2 parts by weight of N, N-dicyclohexyl-2-benzothiazole sulfenamide as an accelerator.

Hereinafter, the present invention will be described in detail.

The present invention is a special reinforcing agent modified by incorporating a silanol component in natural rubber, carbon black aggregates, that is, an ideal filler of carbon black and silica, and simultaneously acts on both carbon black and silica to improve characteristics such as vulcanization rate. A rubber composition for adhering rubber and steel cord of radial tires, characterized in that it consists of a coupling agent, i.e., bis- (3-triethoxysilylpropyl) tetra-sulfane, sulfur, a binder and conventional additives. By using it, it has the effect of improving aging resistance, increasing initial adhesion and preventing cracking caused by stress difference between rubber and steel cord.

In the above, the abnormal filler is a carbon black agglomerate in the existing furnace carbon black process by changing the manufacturing process for introducing oil and air into the reactor by adding the silanol component gas, which is the main component of silica in addition to oil and air into the reactor The silanol component is chemically bonded to the carbon particles, thereby preparing a filler having a silanol component of 3 to 20 parts by weight relative to carbon black. Therefore, the abnormal filler is mixed with the carbon black functional group and the silica functional group is distributed away from each functional group to suppress the reactivity between the filler-filler due to the excessive distribution of functional groups on the surface which is a characteristic of the conventional silica By reducing filler network development, activating the reactivity with filler-rubber and increasing the production of bound rubber in the filler formulation, the ideal formulation to compensate for the disadvantages of silica while maintaining the blending properties of each of the fillers, carbon black and silica, namely In addition, it shows high strength under low elongation conditions and improves aging property at the same time.

The abnormal filler is a filler having a nitrogen adsorption surface area of 90 to 190 square meters per gram, and a DI value of 70 to 150 millimeters per 100 grams.

If the abnormal filler is used in an amount of 5 parts by weight or less, the effect of the abnormal filler is not used, and when used in an amount of 80 parts by weight or more, the processability problem (requires dispersing and special processing technology of the filler) and the vulcanization time are long, so that it is used up to 5 to 80 parts by weight. do.

By using a coupling agent that simultaneously acts on both carbon and silica components, that is, bis- (3-triethoxysilylpropyl) tetra-sulphan, properties such as vulcanization rate are improved. When the coupling agent is used, the exothermic performance can be lowered, but since the strength is lowered under low elongation, the use of 3 parts by weight or less is appropriate.

In the present invention, other types of fillers (including carbon black) usually used as rubber compounding agents, and anti-aging agents, softeners, vulcanizing agents, vulcanization accelerators and the like can be used in combination.

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

Example 1

The rubber composition before vulcanization was prepared according to a conventional procedure using the rubber additives shown in Table 1.

Here, the rubber composition was prepared by a conventional procedure with the composition according to Example 1 of Table 1.

Example 2

A rubber composition was prepared in a composition according to Example 2 of Table 1 by the same procedure as in Example 1.

[Comparative Example]

By the same process as in Example 1 to prepare a rubber composition with a composition according to the comparative example of Table 1.

TABLE 1

[Test Example]

The rubber composition prepared by Examples 1, 2 and Comparative Example was vulcanized at 150 ° C. for 30 minutes, and tested according to ASTM standard D2240 using a Shore A hardness tester for hardness measurement. Tensile strength was evaluated using the Instron 4203 tester using the Instron 4203 tester and tested according to ASTM D412. Tear strength was evaluated using the Instron 4203 tester using the B type test and tested according to ASTM D624. In order to measure the adhesive force was tested using a steel cord standard 3 + 9 + 15 (0.175) + W according to ASTM D2229 and the results are shown in Table 2. The mixed power is Kobe Steel (Japan) BB-4, the mixed rubber content of 2,200 grams, the hardness is the Shore A type, which means room temperature hardness measured, and the thermal aging conditions of the rubber are aged at 100 ° C for 72 hours. In the aging condition of the adhesive force, the thermal aging condition means aging for 2 weeks in air at 100 ° C., and the hot water aging condition means aging for 3 weeks in water.

TABLE 2

Only in the case of using an abnormal filler and a coupling agent (Examples 1 and 2), the hardness, elongation, tensile strength and tear strength were similar to or less than those initially used (comparative example). Later, it was found to be considerably improved compared to the comparative example, and in particular, this tendency was apparent in adhesive strength.

Rubber composition for the adhesion of rubber and steel cords according to the present invention improves the aging resistance and maintains high strength at low elongation conditions to increase the initial adhesive strength and to prevent the occurrence of cracking due to the stress difference between the rubber and steel cords Has

Claims (2)

In the rubber composition for bonding rubber and steel cord, 5 to 80 parts by weight of an ideal filler of carbon black and silica modified by incorporating silanol component on the surface of carbon black with respect to 100 parts by weight of natural rubber, and a bis- 0.1 to 3 parts by weight of (3-triethoxysilylpropyl) tetra-sulfane and 4 to 6 parts by weight of sulfur, which is a common additive, cobaltnaphthenate / resorcinol-formaldehyde / hexamethoxymethylmelamine 10 as binder A rubber composition for adhering the rubber and the steel cord of a radial tire, characterized by comprising 2 parts by weight of N, N-dicyclohexyl-2-benzothiazole sulfenamide as parts by weight and accelerator. The method of claim 1, wherein the abnormal filler is a surface modified by incorporating the silanol component gas to the reaction furnace 3 to 20 parts by weight compared to the carbon black in the reaction furnace by injecting the silanol component gas in the reactor during the manufacturing process of the carbon black Rubber for adhesion of radial tires and steel cords, characterized in that the filler has a nitrogen adsorption surface area of 90 to 190 square meters per gram and a DI value of 70 to 150 millimeters per 100 grams as an ideal filler of carbon black and silica. Composition.