KR100249738B1 - Radial tire for middle load having super high tensile belt - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heavy duty radial tire having an ultra high strength belt. The belt is manufactured by using an ultra high strength steel cord to manufacture a belt to reduce the weight of the tire without harming the plunger energy and dynamic performance of the tire. To form a heavy-duty radial tire.

In order to achieve this purpose, an ultra high strength steel cord (3) having a tensile strength of 350 kg / mm 2 or more and a rigidity of 900 N. mm or more is used, including 100 phr of natural rubber, 50 phr of carbon black, 8 phr of zinc oxide, 4 phr of sulfur, A rubber blend consisting of 0.7 phr of a vulcanization accelerator is used together.

Description

Heavy duty radial tires with belts of super high strength

1 is a perspective view of a steel cord in an ultra high strength belt according to the present invention,

2 is a cross-sectional view of a steel cord for a conventional belt.

* Explanation of symbols for main parts of the drawings

1: core line 2: sideline

3: Steel cord

[Purpose of invention]

The present invention relates to a heavy duty radial tire having an extremely high strength belt (or a belt ply), and more particularly to a plunger energy of a tire by using a super high tensile steel cord in a belt of a heavy duty radial tire. The present invention relates to a method for manufacturing a heavy-duty radial tire using the belt by manufacturing a belt to reduce the weight of the tire without harming Plunger Energy) and dynamic performance.

[Technical field to which the invention belongs and the prior art in that field]

Heavy duty radial tires used for truck buses usually consist of a body ply made of a composite of steel cord and rubber and at least two belt plies, which support the body load and deliver engine power to the ground. Doing. Among them, the body fly plays an important role to form the center skeleton of the tire, and the belt fly plays a role of uniformly distributing the body load on the ground plane while preventing damage to the body fly due to the impact on the ground.

In particular, the sudden impact with protrusions experienced during tire driving can seriously damage the tire, so the industrial standard standards of most developed countries including the Japanese Industrial Standard JIS-D4230 exceed the prescribed values in the tire breaking test. Plunger energy is required.

In order to increase the plunger energy of the tire, the belt ply must have sufficient tensile strength. Conventionally, the tensile strength of the belt ply is increased by increasing the cord diameter of the belt or increasing the number of steel cords used for the belt ply. Was raising. Figure 2 is a cross-sectional view of such a conventional steel cord, the conventional steel cord is composed of six strands (2 ') arranged around three core wires (1') and they are twisted into one body, If the diameter of the cord 3 'is increased to increase the plunger energy of the belt made of steel cord 3' or the heavy duty radial tire including the belt, the rubber thickness of the belt also increases proportionally. The weight of the steel becomes too heavy to meet the aforementioned requirements. On the other hand, when the number of steel cords 3 'is increased, not only is the tire heavy but also the gap between the cords 3' is narrow. Crack propagation easily occurs at both ends of the belt due to the dynamic deformation of the jersey tire, thereby degrading the running durability of the heavy-duty radial tire.

[Technical Problem to Solve]

The present invention has been made to solve the problems of the conventional heavy-loaded radial tires, more specifically, the problems caused by the structure of the steel cord in the belt, while reducing the weight of the tire, while the tensile strength and dynamic performance There is a feature of the present invention to provide an excellent heavy duty radial tire.

In order to achieve the above object, the present invention provides a steel cord having a tensile strength of 350 kg / mm 2 or more and a rigidity of 900 N. mm or more; The belt is composed of a compound rubber having a composition of 100 phr of natural rubber, 8 phr of zinc oxide, 50 phr of carbon black (N323), 4 phr of sulfur, 0.7 phr of accelerator (MOR), 1 phr of stearic acid, and 0.3 phr of cobalt salt.

[Configuration and Function of Invention]

Hereinafter, on the basis of the accompanying drawings, the configuration of a heavy-duty radial tire having an ultra-high strength belt according to the present invention will be described.

Applicant, after much research to develop a heavy-duty radial tire that is excellent in the tensile strength and dynamic performance of the tire while reducing the tire weight, the steel cord used for the belt has a tensile strength of 350kg / ㎜ or more and stiffness ) Was found to be preferably 900 N. mm or more. In addition, as shown in FIG. 1, the diameter D of the steel cord 3 is in the range of 0.8 to 1.0 mm, and the diameter d1 of the core wires and side lines 1 and 2 constituting the steel cord 3. , d2) was selected in the range of 0.25 ~ 0.40mm, the diameter (d2) of the six-sided side line 2 surrounding the core wire (1) was selected to 0.25 ~ 0.35mm.

On the other hand, although the twist pitch of these core wires 1 and the side wire 2 is 14.0-18.0 mm, in the present invention, the reason for limiting the twist pitch of the steel cord 3 to 14.0-18.0 mm is, If the pitch is shorter than 14.0 mm, the stiffness decreases, but the manufacturing cost increases. If the pitch is shorter than 18.0 mm, fatigue resistance and rubber permeability deteriorate.

In the present invention, the E.P.I (number of cords per inch of cross section) of the belt is 12.0 to 16.0 pieces, and the thickness of the belt is 1.5 to 2.0 times the diameter (D) of the steel cord (3). In particular, the rubber layer for planting steel cord is a compound rubber having the composition of natural rubber 100phr, zinc oxide 8phr, carbon black (N323) 50phr, sulfur 4phr, accelerator (MOR) 0.7phr, stearic acid 1phr, cobalt salt 0.3phr The strength should be at least 250 kg / mm 2 or more, and 100% modulus should be at least 100 kg / mm 2 or more.

EXAMPLE

As shown in Table 1, in the 12R22.5 standard, the body ply uses a rubber composite including a steel cord having the same structure as the conventional one, and the first, second, and third belts use the rubber composite according to the present invention, and the tread The fourth belt closest to is made of rubber composite of 3 × 7 structure. In addition, the belt of the embodiment is planted with a steel cord having a structure of 1 × 0.35 + 6 × 0.32 SHT to 14.3 E.P.I, the thickness of the rubber composite is 1.70mm.

TABLE 1

In the present embodiment, a heavy-duty radial tire using 1 × 0.35 + 6 × 0.32 SHT steel cord 3 as a belt cord has excellent durability, rubber permeability, and corrosion resistance. It extends the service life of truck / bus radial tires, which is advantageous in terms of economic and resource activities. In addition, since the rubber composite is thin, the weight of the tire is also reduced by about 6%, which greatly reduces the cost.

However, in the case of the steel cord having the same diameter as the core and the side wire as in Example 2, it is not larger than Example 1 in the effect of corrosion resistance and weight reduction.

[Effects of the Invention]

As described above, when the belt (or belt ply) is manufactured from the steel cord 3 according to the present invention, and the belt is used as the first, second and third belts of the heavy-weight radial tire, the tire durability and the like are more dynamic than before. The performance is excellent and the weight of the tire can be obtained.

In particular, since the rubber permeability is good and the rigidity is high, the body ply is protected from impact, thereby increasing the number of tire regenerations and extending the service life of the tire.

Claims (4)

In a heavy-duty radial tire consisting of a body ply made of a composite of steel cord and rubber and at least two belts used for trucks / buses, the belt has a cord having a diameter (D) of 0.8 to 1.0 mm as a cord. Steel cord (3) is used, but the steel cord (3) has a core (1) of one strand having a diameter (d1) of 0.30 to 0.40 mm in the center and has a diameter (d2) of 0.25 to 0.35 mm around the core. A heavy-duty radial tire with an extremely high strength belt, characterized by a six-sided side line (2) arranged in an integral twist so that the twist pitch is 14.0-18.0 mm. 2. The heavy-duty radial tire according to claim 1, wherein the steel cord (3) has a tensile strength of 350 kg / mm 2 or more and a rigidity of 900 N.mm or more. The rubber compound according to claim 1, wherein the rubber compound used as the rubber layer has a composition of 100 phr of natural rubber, 50 phr of carbon black, 8 phr of zinc oxide, 4 phr of sulfur, 0.7 phr of vulcanization accelerator, and tensile strength of 250 kg / mm 2 or more, 100%. A heavy duty radial tire having an ultra-high strength belt, characterized by a modulus of 100 kg / mm 2 or more. The heavy duty radial tire according to claim 1 or 3, wherein the belt has an E.P.I of 14.3 and a thickness of 1.7 mm.

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