JPH0649784A - Composite cord for reinforcing elastomer good and pneumatic radial tire - Google Patents

Abstract

PURPOSE:To obtain a cord having a single twist structure, exhibiting a high breaking strength and useful for a tire, etc., by combining organic fiber filaments with plural steel filaments mutually adjacently arranged along the peripheral surface of the cord. CONSTITUTION:The objective composite cord for reinforcing an elastomer good, composed of three to five filaments and having a single twist structure is obtained by combining one or more organic fiber filaments 1 with two or more steel filaments 2 and intertwisting both the kinds of filaments in the same layer so that the steel filaments 2 may be mutually adjacently be arranged along the peripheral surface of the cord. In addition, this composite cord is used and arranged in a shape of one layer belt on a carcass composed of a ply of radially arranged cords and toroidally extending between a pair of bead units so as to produce the objective pneumatic radial tire remarkably improved in durability owing to remarkably improved durability to compression deformation applied to the cord and exhibiting light-weight properties realized by using the organic fiber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite cord which is a combination of organic fiber filaments and steel filaments and is used as a reinforcing material for elastomer products such as pneumatic tires and industrial belts. The present invention relates to a pneumatic radial tire in which a belt is arranged on a carcass, and is particularly intended to improve resistance to cord breakage.

[0002]

2. Description of the Related Art Composite cords made by combining organic fiber filaments with the purpose of imparting properties to steel filaments that the steel filaments do not possess are used in elastomer products, typically pneumatic tires. There is.

Regarding this composite cord, the actual code 1-7089
Japanese Patent No. 7 discloses a cord having a 1 × 3 to 5 single twist structure and using 1 to 4 organic fibers. Although these cords are characterized by having a low elastic modulus and a high degree of elongation, they have the following problems.

[0004]

For example, a cord used for reinforcing a tire has a so-called backing on a tread portion of the tire which is an outer side particularly when cornering when an excessive input is applied to the tire during cornering. Since the cord is buckled due to ring deformation, a compressive stress is applied to the cord, which is repeatedly generated, and eventually the cord is broken.

Therefore, an object of the present invention is to provide a composite cord having a 1 × N (N = 2-5, hereinafter the same) structure, which is expected to be lighter in weight and improved in compression fatigue resistance, and which is excellent in cord breaking resistance.
It is the one we are trying to provide.

[0006]

The present invention provides a single twist structure cord composed of 3 to 5 filaments in which a filament made of at least one organic fiber and at least two steel filaments are combined to obtain the steel. The filament is a composite cord for reinforcing an elastomer product, which is characterized in that the filaments are closely arranged along the peripheral surface of the cord. Here, it is preferable that the diameter of the filament made of the organic fiber is smaller than the diameter of the steel filament, and a monofilament or a multifilament can be used as the organic fiber filament. As the organic fiber to be used, polyamide, polyester, etc. are suitable, but not limited to these, various materials can be applied.

Further, the present invention is a pneumatic radial tire having a carcass composed of a ply of radial arrangement cords extending in a toroidal shape between a pair of bead portions as a skeleton, and further having at least one layer of belt on the carcass. And a pneumatic radial tire in which the above composite cord is applied to the belt.

FIG. 1 shows a cross section of a composite cord for reinforcing an elastomer product according to the present invention. In the figure, 1 is an organic fiber filament and 2 is a steel filament, and in this example, it has a single twist structure in which two organic fiber filaments 1 and three steel filaments 2 are twisted in the same layer.

It is important that the steel filaments 2 are arranged closely adjacent to each other along the peripheral surface of the cord in any cross section orthogonal to the longitudinal direction of the cord. That is, the adjacent steel filaments 2 are arranged in contact with each other, or the gap between the filaments 2 is made extremely small so that a plurality of steel filaments 2 always extend in a bundle shape in the cord longitudinal direction to form the organic fiber filaments 1. The structure will be twisted together.

By arranging the steel filaments as described above, when a predetermined twist is applied, the phases between the steel filaments become substantially the same, and the cord breaking resistance is improved.

The diameter of the organic fiber filament is preferably smaller than the diameter of the steel filament in order to improve the cord breaking life. Specifically, the diameter of the organic fiber filament is 0.3 to 0 of the steel filament diameter.
It is advantageous to have a range of 8 times. Eggplant, 0.3
If it is less than twice, wire breakage is likely to occur when twisting the cord, while if it exceeds 0.8 times, rubber penetration between filaments deteriorates.

[0012]

In the present invention, the reason why the steel filaments are closely arranged along the peripheral surface of the cord is as follows. A conventional composite cord having a 1 × 3 twist structure, that is, a conventional cord A in which three steel filaments 2 shown in FIG. 2 are arranged at equal intervals, and two steel filaments 3 shown in FIG. In the conventional cord B arranged side by side in the direction, when there is a compressive bending input, as shown in FIG. 4, a compressive buckling phenomenon occurs at a critical point where a large bending deformation occurs. In the case of the composite cord C according to the present invention shown in FIG. 4, no buckling phenomenon is observed as shown in FIG.

This is because by arranging the steel filaments shown in FIG. 1, that is, by arranging them closely along the peripheral surface of the cord, the phases between the steel filaments become substantially the same, so Even if there is a compressive bending input, multiple steel filaments can absorb the input without buckling, and the deformation of this steel filament can be followed by an organic fiber filament having a lower elasticity than the steel filament. Therefore, it is considered that the buckling phenomenon does not occur because the organic fiber filament can also absorb the compression bending input without causing the buckling.

By the way, the cord proposed in Japanese Utility Model Laid-Open No. 1-70897 mentioned above is not restricted to the arrangement in which the steel filaments are closely arranged along the peripheral surface of the cord, so that the above-mentioned action is expected. Therefore, like the conventional cords A and B, it is difficult to avoid the buckling due to the compressive bending input.

Further, as shown in FIG. 5, in the cord in which the diameter of the organic fiber filament 1 is smaller than the diameter of the steel filament 2, as compared with the cord in FIG. The rubber can easily enter the inside of the cord through the gap, and deformation of the cord can be suppressed especially under compression input, which is extremely advantageous for improving the compression rupture life.

Furthermore, by using an organic fiber filament, the weight of the cord can be reduced, and the cord diameter can be made smaller by making the diameter of the organic fiber filament smaller than the diameter of the steel filament. When applied, it is possible to reduce the belt thickness by reducing the cord diameter, which can greatly contribute to the weight reduction of the tire.

The steel cord having the above structure can be suitably used as a reinforcing material for belts and chafers of pneumatic tires. That is, the tread surface of the tire, which is on the outside during cornering, periodically floats up against the road surface, causing buckling deformation, reducing the tread's ground contact area and reducing cornering performance. There is a disadvantage leading to breakage. However, the code according to the invention is
By applying it to a tire, especially to a belt, buckling deformation is suppressed, cornering performance is improved, and cord breakage can be avoided.

[0018]

EXAMPLES 1 × 5 structure shown in FIGS. 1, 6 and 7, 1 × 4 structure shown in FIG. 8, 1 × 3 structure shown in FIGS. 9 and 10, and the diameter of the organic fiber filament 1 to the diameter of the steel filament 2 Smaller than 1x shown in Figures 5, 11 and 12
5 structure, 1 × 4 structure shown in FIGS. 13 and 14, 1 shown in FIG.
A composite cord having a × 3 structure was prototyped according to Tables 1 to 3 to prepare a test piece in which each cord was embedded in rubber. Aromatic polyamide was used for the organic fiber filament. For comparison, a conventional cord having the structure shown in FIGS. 2, 3 and 16 was prototyped according to Table 1, and a test piece was similarly prepared.

The test pieces thus obtained were subjected to a compression characteristic test and a compression fatigue test, and the results are shown in Tables 1 to 3 together. In the compression characteristic test, the presence or absence of a buckling point in the displacement-stress curve when the test piece was compressed in the cord axis direction was investigated. In the compression fatigue test, the compression input in the compression characteristic test was repeatedly applied until the cord broke, and the number of times was examined.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Table 3]

In addition, the composite cords shown in Tables 1 to 3 were used for the radial tires for passenger cars of tire size 175 / 70R13.
Applied to a belt of layers. Then, tires with an internal pressure of 1.8 kgf / mm ² were mounted on a normal passenger car, and the cornering performance when driving through a corner with a radius of 80 m was evaluated by the driver on a 10-point scale, and with side force added. After traveling in, the tire was disassembled and the number of broken cords in the belt was examined. These evaluations and survey results are shown in Tables 4 to 6 together with the specifications of the belt.

[0024]

[Table 4]

[0025]

[Table 5]

[0026]

[Table 6]

[0027]

According to the steel cord for reinforcing an elastomer product of the present invention, the durability of the elastomer product can be remarkably improved because the durability of the steel cord for reinforcing the elastomer product is significantly improved. Above all, when applied to a tire which is frequently subjected to compressive deformation, not only the durability can be naturally improved, but also the weight reduction of the tire can be achieved by the organic fiber.

[Brief description of drawings]

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

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

FIG. 3 is a cross-sectional view of a conventional steel cord.

FIG. 4 is a graph showing the relationship between compressive strain (%) and compressive stress (kgf) of a cord.

FIG. 5 is a sectional view of a steel cord according to the present invention.

FIG. 6 is a sectional view of a steel cord according to the present invention.

FIG. 7 is a sectional view of a steel cord according to the present invention.

FIG. 8 is a sectional view of a steel cord according to the present invention.

FIG. 9 is a sectional view of a steel cord according to the present invention.

FIG. 10 is a sectional view of a steel cord according to the present invention.

FIG. 11 is a sectional view of a steel cord according to the present invention.

FIG. 12 is a sectional view of a steel cord according to the present invention.

FIG. 13 is a sectional view of a steel cord according to the present invention.

FIG. 14 is a sectional view of a steel cord according to the present invention.

FIG. 15 is a sectional view of a steel cord according to the present invention.

FIG. 16 is a cross-sectional view of a conventional steel cord.

[Explanation of symbols]

 1 Organic fiber filament 2 Steel filament

Claims (3)

[Claims] 1. A single twist structure cord composed of 3 to 5 filaments in which at least one filament made of an organic fiber and at least two steel filaments are combined, and the steel filament is provided on the peripheral surface of the cord. A composite cord for reinforcing an elastomer product, which is characterized in that the cords are arranged closely adjacent to each other. 2. The composite cord according to claim 1, wherein the diameter of the filament made of the organic fiber is smaller than the diameter of the steel filament. 3. A pneumatic radial tire having a carcass composed of a ply of radial array cords extending in a toroidal shape between a pair of bead portions as a skeleton, and further having at least one layer of belt on the carcass. To
A pneumatic radial tire to which the composite cord according to claim 1 or 2 is applied.