JPH09228271A - Steel cord for reinforcing rubber article and pneumatic radial tire using the steel cord - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a steel cord excellent in rubber infiltrativity despite having multiply laid structure made up of core strand and sheath strand each composed of plural wires, and excellent in resistance to corrosion and buckling fatigue, thus suitable for use in pneumatic tires. SOLUTION: This steel cord is so designed that each of sheath strands 4 constituting sheath layer is composed of three filaments 3 arranged in nearly parallel with one another, the sheath strands 4 include strand A containing at least one filament 3 subjected to a pitch P (5Dt<=P<=40Dt; Dt is filament diameter) and preforming or postforming at a level of R (0.3Dt<=R<=3Dt) in the form of wave, helix or their combination; and at least cane of the three filaments 3 adjacent to one another in each of the sheath strands 4 represents the strand A, or a strand B composed of two filaments 3 arranged in nearly parallel with each other. The other objective pneumatic tire is obtained by using these steel chords for reinforcing the belt of the tire.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, for reinforcement of rubber products such as pneumatic tires, in steel cords that are used by being embedded in rubber, moisture propagates in the longitudinal direction of the cord when a cut is made in the rubber product, Rubber has been required to penetrate into the cord to prevent corrosion from spreading.

In the conventional technology, (a) the number of sheaths and the wire diameter are larger than the wire diameters of the open twisted cord in which the filaments are excessively shaped and the gaps between the filaments are provided, and (b) the core strand. Cords with gaps between filaments by specifying, (C) 1x2, 2+
Cords having an improved twist structure such as 2, 4 × 2 are mainly known as a method for enhancing rubber penetration.

[0004]

However, since it is difficult to obtain the cord strength with the cord structure (a) or (c) described above, it is used as a reinforcing layer for protecting the inner layer from small tires and external damage. However, it was unsuitable as a reinforcing layer for a medium-sized or larger tire. Further, although the cord strength is easily obtained by the method (b), there is a problem that the arrangement of the constituent filaments is apt to be biased and the penetration of the rubber into the cord is not stable.

Therefore, an object of the present invention is to provide a rubber article excellent in rubber permeability, corrosion resistance and buckling fatigue resistance even though it has a double-twisted structure of two or more layers in which rubber hardly penetrates into the inside. To provide a reinforcing steel cord and a pneumatic tire using the same.

[0006]

To achieve the above object, in a steel cord for reinforcing a rubber article having a two-layer or three-layer multi-twist structure of the present invention, the cores are aligned substantially parallel to each other. 3 filaments, each sheath layer being aligned in parallel with each other, and at least one filament having a pitch P (5Dt ≦ P
≦ 40 Dt: Dt is the filament wire diameter) and the die attachment amount R
(0.3Dt ≦ R ≦ 3Dt) corrugated or spiral shape or a combination of these strands (A)
And at least one of three adjacent sheaths in each sheath layer is defined as the above-mentioned strand (A) or a strand (B) consisting of two filaments aligned substantially in parallel (however, When the number of sheaths in each sheath layer is two, at least one consists of the strand (A) or the strand (B), and the rest consists of ordinary filaments.

In the present invention, instead of the core, the core may be a strand formed by twisting two filaments.

Further, in the steel cord for reinforcing rubber articles having a two-layer or three-layer double twist structure of the present invention, the core is
Each sheath layer is composed of one filament, and each sheath layer is three filaments aligned in parallel, and at least one of them has a pitch P (5Dt ≦ P ≦ 40).
Dt: Dt is the filament wire diameter) and the die amount R (0.
3Dt ≦ R ≦ 3Dt) at least one of two adjacent sheaths in a sheath layer adjacent to the core, the strand (A) having a corrugated shape or a spiral shape or a combination thereof. Is the strand (A) or a strand (B) composed of two filaments aligned in parallel (however, when the number of sheaths in each sheath layer is two, at least one is the above-mentioned strand). (A) or the above-mentioned strand (B)), and the rest consists of ordinary filaments.

In the present invention, all of the sheaths constituting each sheath layer can be either the strand (A) or the strand (B).

After the sheaths constituting the respective sheath layers,
The diameter of the filament of the sheath consisting of one filament is Dm, and the diameter of the filament of the strand (A) is D
t, when the filament diameter of the strand (B) is Dd, it is preferable that the following equation be satisfied: Dd ≦ Dm ≦ 2Dd Dt ≦ Dm ≦ (1 + 2 / √3) Dt, and more preferably the filament diameter. Dt and the filament diameter Dd are set to satisfy the following equation: Dd = Dt.

The present invention also relates to a pneumatic tire in which the steel cord for reinforcing rubber articles is applied to a belt.

Conventional 1 + n (FIG. 17) or 1 ×
With a code such as 2 + n, even if it is set so that there is a gap between the sheaths, the sheath is biased and
There is a problem that the rubber cannot penetrate the voids, and the voids continue in the longitudinal direction, so that the corroded portion expands when water enters due to a cut or the like. On the other hand, in the steel cord of the present invention,
By applying the strand (A) or the strand (B) composed of three filaments to the sheath, cord strength is easily exhibited, and in particular, the strand (A) is untwisted and imprinted in the above range. By this, the rubber can be permeated without impairing the cord strength.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In a steel cord for reinforcing a rubber article according to the present invention, each sheath layer is composed of three filaments aligned in parallel, and at least one of them has a pitch P (5Dt ≦ P). ≤40Dt: Dt
Is the filament wire diameter) and the die attachment amount R (0.3Dt ≦ R
≦ 3 Dt) corrugated or spiral shape or a combination of the shaped strands (A), and at least one of three adjacent sheaths in each sheath layer
The book is the above-mentioned strand (A) or a strand (B) composed of two filaments that are aligned in parallel, and the rest is composed of ordinary filaments. However, when there are two sheaths forming each sheath layer, at least one sheath is the strand (A) or the strand (B). In addition, here, the molding amount R is defined as the amplitude amount of the molding.

The reason why at least one filament of the filaments of the strand (A) is imprinted is to allow the rubber to penetrate into the portion surrounded by the three filaments. When the pitch P and the molding amount R of this molding become P <5Dt or R> 3Dt, the alignment becomes poor when a tensile input is applied to the cords, and the strength decreases. On the other hand, when P> 40 Dt and R <0.3 Dt, the effect of molding becomes small and the rubber penetration becomes poor. In addition, by aligning them substantially in parallel,
As described above, the void portion where the rubber cannot penetrate does not continue in the longitudinal direction, so that good rubber permeability can be maintained.

Here, in the present invention, in the case where the core is composed of two filaments which are aligned in parallel to each other or a strand formed by twisting two filaments, the cores are adjacent to each other in each sheath layer. At least one of the three sheaths is the strand (A) or the strand (B), as shown in FIG. 13, when the three adjacent sheaths are ordinary monofilaments,
This is because the void portion b in which the rubber cannot penetrate is generated and is easily connected in the cord longitudinal direction, which deteriorates the rubber permeability.

When the core is composed of one filament, at least one of the two adjacent sheaths in the sheath layer adjacent to the core is the strand (A) or the strand (B). This is because if the two adjacent sheaths are monofilaments, a rubber impermeable portion will be generated in the portion surrounded by these sheaths and the core filament.

Further, the cord of the present invention has advantages such as good productivity and less loss of strength because it is not necessary to pretwist the sheath strand in advance.

In the present invention, in order to make it easier for the rubber to penetrate into the inside of the cord, each filament or strand itself constituting the sheath may be corrugated or spiral-shaped.

Further, in the present invention, after the sheath constituting each sheath layer, the filament diameter of the sheath consisting of one filament is Dm, the filament diameter of the strand (A) is Dt, and the strand (B) is When the diameter of the filament is Dd, it is preferable from the viewpoint of the heavy load between the filaments and the production of the cord that the following formula is satisfied: Dd ≦ Dm ≦ 2Dd Dt ≦ Dm ≦ (1 + 2 / √3) Dt. = Dt is more preferable.

[0020]

Next, the present invention will be described in detail with reference to examples. Steel cords were produced according to Tables 1 and 2 below. Examples 1 to 10 of these steel cords
1 to 10, respectively, and cord sections of Comparative Examples 1 to 3 in FIGS. 11 to 13, respectively, and Examples 11 to 1
14 to 16 are sectional views of the cord of No. 3 respectively.

Next, radial tires for trucks and buses of size 10.00R20 equipped with a belt made of such steel cord were prototyped, and the respective tires were tested for corrosion propagation resistance and buckling fatigue resistance. It was The results are also shown in Tables 1 and 2 below. The corrosion propagation resistance is a maximum value of the length of the corroded portion extending from the cut portion of the damaged portion, measured in the cord direction, of the tire that has been completely worn due to running on rough roads.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

[Table 3] * 1 cr + 2 represents one strand (A).

[0025]

INDUSTRIAL APPLICABILITY The steel cord for reinforcing rubber articles of the present invention has a two-layer or three-layer double-twisted structure, which is advantageous for expressing the cord strength, and has good rubber penetration, and corrosion resistance propagation. And excellent buckling fatigue resistance. Further, by applying the cord to the belt layer of the pneumatic radial tire, a pneumatic tire excellent in durability and weight reduction can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a steel cord according to a first embodiment.

FIG. 2 is a sectional view of a steel cord according to a second embodiment.

FIG. 3 is a sectional view of a steel cord according to a third embodiment.

FIG. 4 is a sectional view of a steel cord according to a fourth embodiment.

FIG. 5 is a sectional view of a steel cord according to a fifth embodiment.

FIG. 6 is a sectional view of a steel cord according to a sixth embodiment.

FIG. 7 is a sectional view of a steel cord according to a seventh embodiment.

FIG. 8 is a sectional view of a steel cord of Example 8.

FIG. 9 is a sectional view of a steel cord according to a ninth embodiment.

FIG. 10 is a sectional view of a steel cord of Example 10.

11 is a cross-sectional view of a steel cord having a normal 1 + 5 structure of Comparative Example 1. FIG.

12 is a cross-sectional view of a steel cord having a normal 1 + 6 + 12 structure of Comparative Example 2. FIG.

13 is a cross-sectional view of a steel cord having a normal 1 + 5 structure of Comparative Example 3. FIG.

FIG. 14 is a sectional view of a steel cord according to an eleventh embodiment.

FIG. 15 is a sectional view of a steel cord of Example 12;

FIG. 16 is a sectional view of a steel cord of Example 13;

FIG. 17 is a cross-sectional view of a conventional 1 × 6 structure steel cord.

[Explanation of symbols]

 1 Core Filament 2 Core Strand 3 First Sheath Filament 4 First Sheath Strand 5 Second Sheath Filament 6 Second Sheath Strand a, b Gap

Claims (7)

[Claims] 1. A steel cord for reinforcing a rubber article having a two-layer or three-layer double-twisted structure, wherein a core is composed of two filaments aligned in parallel, and each sheath layer is drawn in parallel. Of three aligned filaments, at least one of them has a pitch P (5Dt ≤ P ≤ 40Dt: Dt is the filament wire diameter) and a corrugated amount R (0.3Dt ≤ R ≤ 3Dt) or a spiral shape. Or, at least one of three adjoining sheaths in each sheath layer, which includes a strand (A) having a pattern formed by combining them, is aligned in parallel with the strand (A) or substantially parallel. (B) when the number of the sheaths in each sheath layer is 2, at least one of the strands (A) or Serial strand (B)),
Steel cord for reinforcing rubber articles, characterized in that the rest consists of ordinary filaments. 2. The steel cord for reinforcing rubber articles according to claim 1, wherein the core is a strand formed by twisting two filaments instead of the core. 3. A steel cord for reinforcing a rubber article having a two-layer or three-layer double-twisted structure, wherein the core is composed of one filament, and the respective sheath layers are aligned in substantially three filaments. At least one of them has a pitch P (5Dt ≤ P ≤ 40Dt: Dt is a filament wire diameter) and a die attachment amount R (0.3Dt ≤ R ≤ 3Dt) or a spiral shape or a combination of them. At least one of two adjoining sheaths in a sheath layer adjacent to the core and including the strand (A) provided with the above-mentioned strand (A), or two aligned substantially in parallel. (B) when the number of sheaths in each sheath layer is 2, at least one of the strands (A) or De (B)), steel cord for reinforcement of rubber articles, characterized in that the remainder consists of normal filaments. 4. All of the sheaths constituting each sheath layer are the strand (A) or the strand (B).
The steel cord for reinforcing rubber articles according to any one of claims 1 to 3, which is any one of the strands of. 5. The diameter of the filament of a sheath composed of one filament after the sheath constituting each sheath layer is D
m, the diameter of the filament of the strand (A) is Dt,
When the diameter of the filament of the said strand (B) is set to Dd, the relationship of following Formula, Dd <= Dm <= 2Dd Dt <= Dm <(1 + 2 / √3) Dt, The relationship of any one of Claims 1-4 is satisfy | filled. Steel cord for reinforcing rubber articles. A steel cord for reinforcing a rubber article according to claim 1 or 2. 6. The steel cord for reinforcing rubber articles according to claim 5, wherein the filament diameter Dt and the filament diameter Dd satisfy the following equation: Dd = Dt. 7. A pneumatic tire in which the steel cord for reinforcing rubber articles according to claim 1 is applied to a belt.