JPH08176981A - Steel cord and pneumatic radial tire - Google Patents

Abstract

PURPOSE: To produce a steel cord to be used as a reinforcing material for elastomer products such as pneumatic radial tires and intended to improve the durability of such pneumatic radial tires. CONSTITUTION: In a strand having 1 to 3 core filaments and having a two- or three-layered, so-called layer-stranded structure, the core or sheath filaments in at least one layer have the closest structure, and at least one of such filaments has a partly preformed or postformed profile over its longer direction and is characterized by that the distance between two preformed/postformed points adjacent to each other is 3 to 10cm. This steel cord is obtained by entwining plural number of the above strands and thus has a plural-stranded structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel cord used as a reinforcing material for rubber articles such as industrial belts, and a pneumatic radial tire using the same.

[0002]

2. Description of the Related Art Conventionally, in a steel cord having a multi-twist structure used as a reinforcing material for a rubber article, rubber is unlikely to enter the inside of the cord due to its structure, and a reduction in corrosion resistance due to cutting has been a problem. It was Further, when the core or the sheath had a filament number enough to have a close-packed structure, rubber was difficult to enter especially in the central portion of the cord.

Here, the method of reducing the number of a part of the filaments of the core or sheath layer having the close-packed structure to form a gap from the outer side of the cord toward the central part to facilitate the intrusion of rubber has a corrosion resistance. Is effective, but there is a problem that the tensile rigidity is not sufficient because the number of filaments is reduced.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to obtain a steel cord having a multi-twisted structure which is excellent in corrosion propagation due to the intrusion of rubber to the inside of the cord while maintaining sufficient tensile rigidity. Further, the present invention relates to a pneumatic radial tire having both corrosion propagation resistance and steering stability by using the same.

[0005]

In order to achieve the above object, in the present invention, (1) the number of core filaments is 1 to 2;
In a layer or a three-layer strand having a so-called layer twist structure, at least one core or sheath has a close-packed structure, and at least one filament of the layer having the close-packed structure is partially distributed in the longitudinal direction. A steel cord for reinforcing a rubber article having a multi-twisted structure in which a plurality of strands are twisted together, which has a molded shape and a distance between one molding and one molding is 3 cm or more and 10 cm or less.

(2) In the above (1), preferably, the partially shaped filament is shaped in a corrugated shape, and a steel for reinforcing a rubber article having a multi-twisted structure in which a plurality of strands are twisted together. code.

(3) In (1) above, for reinforcing a rubber article having a multi-twisted structure in which a plurality of strands are twisted, characterized in that the shape of the partially shaped filaments is preferably helical. Steel cord.

(4) A pneumatic radial tire using the steel cord according to the above (1) to (3) in a belt layer of the tire.

[0009]

The present invention has the following actions. That is, in a two-layer or three-layer strand-twisted strand having 1 to 3 filaments in the core, at least a part of the filaments in the layer having the close-packed structure extends in the longitudinal direction,
By molding a part instead of the whole, it is possible to suppress deterioration of steering stability due to variations in tensile load of tensile rigidity and compression rigidity for each filament, facilitate rubber intrusion, and corrosion propagation resistance Is an improvement.

The length from one embossing to the next embossing of the filaments imprinted here is 3
10 cm is suitable. If this length is less than 3 cm, the variation in the load of tension with other unmolded filaments will increase, and the steering stability will decrease when applied to pneumatic tires. On the other hand, if it is larger than 10 cm, it is difficult for the rubber to enter and the corrosion propagation resistance is deteriorated.

Regarding the shape of the molded part,
In terms of its manufacture, it is preferable to use a corrugated or spiral mold, but other forms may be used as long as the rubber penetrates.

Regarding the length of the shaped part,
If the rubber sufficiently penetrates, it is preferable that the length is as short as possible. Further shaping is accomplished, such as by partially passing the rollers through the twisting of the filaments.

[0013]

[Examples] Table 1 shows the test results of rubber permeability, which is an index of durability, steering stability when applied to tires, and corrosion propagation resistance, in Examples and Comparative Examples of the present invention. ing.

[0014]

[Table 1]

The tires used in the tests shown in Table 1 are tubeless tires having the following structure. Tire size: 18.00 R33 Carcass: (1 + 6) x0.21 + 6x (1 + 6) x0.21 Steel cord with structure Belt layer: 4 pieces separated structure

The test methods for steering stability and corrosion fatigue resistance listed in Table 1 are as follows. [Steering stability] For the steering stability, a feeling test was conducted by mounting the manufactured tire on an actual vehicle. 1 tire of Comparative Example 1
00 and displayed as an index. The larger the value, the better. [Corrosion fatigue resistance] After running a prototype tire on the road for 20,000 km, the tire was dissected and the location of rust in the cord was examined, and the length of the portion where the rust was most developed was displayed as an index. .

The example using the steel cord having the layer-twisted structure of the present invention has a sufficient rubber permeability as compared with the comparative example, and the pneumatic tire using the same has the comparative example. Compared to tires using tires, steering stability and corrosion resistance are excellent.

In Comparative Example 1, since the filaments are in contact with each other over the entire longitudinal direction, the rubber does not sufficiently penetrate into the inside of the cord and there is a problem in corrosion propagation resistance. Further, in Comparative Example 2, since the distance between the mold parts is short, the steering stability is poor. Further, in Comparative Example 3, since the distance between the mold parts is too long, the rubber does not sufficiently penetrate like Comparative Example 1, and the corrosion propagation resistance is poor.

[0019]

EFFECT OF THE INVENTION According to the steel cord for reinforcing a rubber article of the present invention, rubber penetrates even into the cord, and a cord having excellent durability can be obtained. Further, by applying the cord to the belt layer of a pneumatic radial tire within the scope of the present invention, a pneumatic tire having more excellent steering stability and corrosion propagation resistance can be obtained.

[0020]

[Brief description of drawings]

1 is a cross-sectional view of a steel cord according to the present invention.

FIG. 2 illustrates a distance between mold parts of a filament and a length of a mold part.

FIG. 3 shows an example of filament morphology according to the present invention.

[Explanation of symbols]

 1 Filament a Distance between typed parts b Length of typed part L Amount of typed

Claims (4)

[Claims] 1. In a strand having a so-called layer twist structure of 2 layers or 3 layers having 1 to 3 filaments in the core, at least one layer of the core or sheath has a close-packed structure, and the close-packed structure thereof. At least one of the filaments of the layer having a shape having a partially shaped shape in the longitudinal direction, and the distance between the one shaping and the one shaping is 3 cm or more and 10 cm or less A steel cord for reinforcing rubber articles with a double twist structure in which multiple strands are twisted together. 2. A steel cord for reinforcing a rubber article having a multi-twisted structure in which a plurality of strands are twisted together, wherein the partially shaped filament has a corrugated shape. 3. A steel cord for reinforcing a rubber article having a multi-twist structure in which a plurality of strands are twisted together, wherein the shape of the partially shaped filament is helical. 4. A pneumatic radial tire using the steel cord according to any one of claims 1 to 3 in a belt layer of a tire.