JPH05186978A - Steel cord - Google Patents

Abstract

PURPOSE:To obtain the subject product, good in rubber penetrability and excellent corrosion propagation resistance and capable of providing tires, etc., good in productivity and improved in durability by subjecting a core filament of a steel cord having a (1+5) structure to suitable waveform shaping. CONSTITUTION:The objective product is a steel cord having a sheath 2, composed of 6 steel filaments and arranged around a core 1 composed of one steel filament. The core filament 1 is shaped into a waveform so that the shaping ratio (RC) which is the ratio of the amplitude (LC) to the element wire diameter (dC) of the core filament 1 is 0.12-1.5 and the pitch (PC) of waveform shaping may satisfy the formula 3dC/0.34<=PC<=10dC/0.34. A waveform having a gentle curve such as a sine wave is preferred as the waveform. The core filament 1 and the sheath filaments 2 preferably have the same diameter for enhancing the productivity.

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 pneumatic tires and industrial belts. More specifically, it suppresses corrosion propagation due to moisture or the like and improves corrosion propagation resistance. Regarding steel cord.

[0002]

2. Description of the Related Art In a product reinforced with a steel cord, there is a problem that the durability of the product is shortened due to the corrosion of the steel filament due to the water infiltrated into the product.

For example, in a steel cord used for a belt of a tire, when the steel cord has a cavity, when the tire tread or the belt is injured to reach the belt, moisture that has penetrated into the belt causes the cavity in the steel cord to be damaged. As a result, the cord spreads along the longitudinal direction of the cord, and as a result, rust due to water also diffuses, and the adhesive force between the rubber and the steel cord in that portion is reduced, and eventually a separation phenomenon occurs.

In order to prevent such corrosion propagation, therefore, a cord structure has been proposed in which rubber is sufficiently penetrated into the cord through a gap between adjacent metal filaments by pressure vulcanization.

First, Japanese Patent Publication Nos. 62-21641 and 60
Japanese Patent Publication No. 49421/1992 discloses that the filaments of the cord are provided with a gap by excessively shaping. However, it is difficult to maintain the gap, and there is a disadvantage that the effect is influenced by the handling in the tire manufacturing process.

On the other hand, a technique for improving the cord structure to secure a gap between the filaments regardless of the type of the filament is disclosed in JP-A-1-175503, in which one core filament and six sheath filaments are used. A steel cord consisting of
In Japanese Patent No. 8204 and Japanese Patent Laid-Open No. 2-154086,
A two-layer twisted steel cord composed of a core made of two metal wires and a sheath filament arranged around the core is disclosed.

[0007] In particular, the 1 + 6 cord disclosed in Japanese Patent Laid-Open No. 175503/1989 allows one-step twisting, which is advantageous in terms of productivity. However, in the disclosed 1 + 6 cord, the diameter of the core filament is made larger than the diameter of the sheath filament so that a certain gap or more is secured between the adjacent sheath filaments so that the rubber penetrates to the inside. As a result, the sheath filaments are unevenly arranged, and rubber does not permeate on the side where the sheath filaments are in close contact with each other. I can't get sex. Further, there are problems such as an increase in cord weight and deterioration of productivity.

Further, in the 1 + 5 structure as disclosed in JP-A-56-131404, since the core filament diameter is smaller than the sheath filament diameter, the distance between the sheath filaments is narrowed, rubber is hard to enter, and the core Since the rigidity is weakened, the effect of corrugation is lowered, and the strength is lowered even when the die-casting ratio is increased to improve the permeability of rubber.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is to improve the permeability of rubber of the cord having the conventional 1 + 6 structure as described above, and to further improve the permeability of the steel cord having the 1 + 7, 1 + 8 structure, which has been difficult to penetrate the rubber. The purpose of the present invention is to provide a steel cord having a 1 + 6, 1 + 7, 1 + 8 structure, which has improved corrosion propagation resistance by increasing rubber permeability.

[0010]

As a result of earnest research to solve the above problems, the present inventor has found that 1 + 6, 1+
By using the core filament of the steel cord of 7, 1 + 8 structure and the filament having substantially the same diameter as the sheath filament, and by appropriately corrugating it, sufficient rubber is applied to the steel cord after pressure vulcanization. The present invention has been completed by discovering that stable penetration is possible.

That is, the present invention is: (1) A core made of one steel filament,
A core is provided with a sheath made of six steel filaments arranged around the core, and the core filament is shaped in a corrugated form, and is represented by the ratio of the amplitude Lc of the corrugated form and the strand diameter dc of the core filament. Molding rate Rc
(= Lc / dc) is 0.12 ≦ Rc ≦ 1.5, and the pitch Pc of the corrugated pattern is 3.0 dc / 0.34 ≦ Pc ≦ 10.
A steel cord for reinforcing a rubber article, which is 0 dc / 0.34,

(2) A core made of one steel filament and a sheath made of seven steel filaments arranged around the core are provided, and the core filament is shaped in a corrugated shape. Amplitude Lc
And the stranding diameter Rc (= Lc / dc) represented by the ratio of the core filament diameter dc to 0.48 ≦ Rc ≦ 1.
86 and the pitch Pc of the corrugated pattern is 3.0 dc / 0.34 ≦ when the core filament diameter is dc.
A steel cord for reinforcing rubber articles, wherein Pc ≦ 10.0 dc / 0.34,

(3) A core made of one steel filament and a sheath made of eight steel filaments arranged around the core are provided, and the core filament is shaped in a corrugated shape. Amplitude Lc
Of the core filament and the filament diameter dc of the core filament have a molding ratio Rc (= Lc / dc) of 0.98 ≦ Rc ≦ 2.
36 and the pitch Pc of the corrugated pattern is 3.0 dc / 0.34 ≦, where dc is the core filament diameter.
A steel cord for reinforcing rubber articles, wherein Pc ≦ 10.0 dc / 0.34,

(4) Carbon content is 0.80 to 0.85
The steel cord according to any one of the above items (1), (2), and (3), which is% by weight,

(5) The steel cord according to any one of items (1), (2), (3) and (4), wherein the core filament diameter dc and the sheath filament diameter ds are substantially dc = ds. ..

The present invention will be described in detail below. In the present invention, the core filament is corrugated. It is important that this waveform has a specific range of amplitude and pitch due to the steel cords of each structure of 1 + 6, 1 + 7, and 1 + 8, which secures a rubber permeation gap between the sheath filaments. , This corrugation has good productivity and low cost, and when the core filament is corrugated, the cord itself becomes a flat cord, and it is possible to prevent an increase in cord thickness due to the molding.
The gauge can be reduced and the rubber layer can be thinned. Further, since the rubber has good permeability, it has advantages such as increased corrosion resistance.

Here, the typed waveform is preferably a waveform having a gentle curve such as a sine wave rather than a pointed shape such as a triangle, and stress is concentrated at the apex. Can be prevented.

When there are 6 sheath filaments, that is, 1
In the case of +6 structure, the molding ratio Rc of the core filament
(= Lc / dc, where Lc is the amplitude of the waveform and dc is the core filament wire diameter) is 0.12 ≦ Rc ≦ 1.5.
When Rc is less than 0.12, the sheath arrangement is dispersed, the sheath gap is properly secured, and the effect of permeating rubber inside the cord is insufficient. When Rc exceeds 1.5, the cord properties are poor and the cord This is because when a tensile load is applied to, the stress is not evenly applied and the cord strength is reduced.

When the number of sheath filaments is 7, that is, 1
In the case of +7 structure, the molding ratio Rc of the core filament
Is set to 0.48 ≦ Rc ≦ 1.86. When Rc is less than 0.48, there are the same drawbacks as when Rc <0.12 when 1 + 6, and when Rc exceeds 1.86 the same as when Rc> 1.5 when 1 + 6. There are drawbacks.

When there are 8 sheath filaments, that is, 1
In the case of +8 structure, the molding ratio Rc of the core filament
Is 0.98 ≦ Rc ≦ 2.36. When Rc is less than 0.98, there are the same drawbacks as when Rc <0.12 when 1 + 6, and when Rc exceeds 2.36 the same as when Rc> 1.5 when 1 + 6. There are drawbacks.

Corrugation molding pitch Pc of core filament
For each of the structures 1 + 6, 1 + 7, and 1 + 8, 3.0 dc / 0.34 ≦ Pc ≦ 10.0 dc / 0.
34. If Pc is greater than 10.0 dc / 0.34, the effect of dispersing the arrangement of the sheath, ensuring an appropriate sheath gap, and allowing rubber to penetrate into the cord is insufficient.
Is less than 3.0 dc / 0.34, the strength of the core filament decreases due to the load on the core filament at the time of molding, and a uniform load is applied to the core filament and the sheath filament during the tensile load on the cord. Without taking
The code is not strong enough.

As a reinforcing material, in order to secure the strength and reduce the weight of the rubber composite, the carbon content is 0.80 to 0.80.
It is preferable to use a steel cord made of 0.85% by weight of high tensile strength steel material.

When the diameter of the core filament is made smaller than the diameter of the sheath filament, the spacing between the sheath filaments is narrowed, it is difficult for rubber to enter, and the rigidity of the core is weakened, so that the effect of molding is deteriorated. Further, when the core filament diameter is made larger than the sheath filament diameter, there are problems such as an increase in cord weight and deterioration in productivity. Therefore, from the standpoint of improving productivity in the manufacturing process,
It is preferable that the core filament diameter dc and the sheath filament diameter ds have substantially the same diameter.

[0024]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The steel cords having the core filament diameter dc, the sheath filament diameter ds, the cord structure, the core corrugated patterning ratio Rc, the core corrugated pitch Pc, and the sheath twist pitch Ps described in Table 1, Table 2, Table 3, and Table 4 were embedded. Size 10.00R2 with belt
19 types of radial tires for trucks and buses were prototyped, and the corrosion propagation resistance (separation resistance) and cord strength of each tire were examined. The results are shown in Table 1.
~ Also shown in the lower part of Table 4.

For corrosion resistance, 100 mm of the belt cord with the rubber covered is taken out from the tire, and one side of the cord is covered with a silicone sealant.
Dip in 0% NaOH aqueous solution to infiltrate the aqueous solution only from the cut surface, then immerse it for 24 hours, pinch the rubber off with pliers, and remove the exposed metal as a corrosion propagation part, and evaluate the length (mm). ..

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

[0029]

[Table 4]

In Comparative Example 1, the core die coverage is smaller than 0.12, and the corrosion propagation resistance is 100 mm, which is poor. Comparative example 2
Shows that the cord strength is inferior at 182 kgf when the pitch Pc of the waveform of the core is smaller than 3.0 dc / 0.34. In Comparative Example 3, when the core die attachment ratio is larger than 1.5, the cord strength is inferior at 180 kgf. Comparative Example 4 is poor in corrosion propagation resistance of 100 mm when the core pitch Pc is greater than 10.0 dc / 0.34. In each of Comparative Examples 5 and 6, the corrugation is not molded on the core filament, and the corrosion propagation resistance is poor. In Comparative Example 7, the die-casting ratio of the core is larger than 1.5, and 0.23 mm strands are used for the core and the sheath, but the cord strength is inferior at 80 kgf. Comparative Example 8
In the 1 + 7 structure, when the core die attachment rate is smaller than 0.48, the corrosion propagation resistance is inferior. Comparative Example 9 has a 1 + 8 structure,
When the core die coverage is less than 0.98, the corrosion propagation resistance is poor.

[0031]

EFFECT OF THE INVENTION The steel cord of the present invention has good productivity, is less affected by variations in the process, and has good rubber permeability, so it has good corrosion propagation resistance and can retain cord strength. When used as a rubber reinforcing material, the durability of a rubber composite such as a tire can be improved and its service life can be significantly improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a steel cord having a 1 + 6 structure according to the present invention.

FIG. 2 is a sectional view of a conventional steel cord having a 1 + 6 structure (one having a large core diameter and not having a mold).

FIG. 3 is a cross-sectional view of a corrugated surface of a corrugated core of the present invention, which is an explanatory diagram of a core wire diameter dc, a waveform amplitude Lc, and a waveform pitch Pc.

FIG. 4 is a sectional view of a steel cord having a 1 + 7 structure according to the present invention.

FIG. 5 is a sectional view of a steel cord having a 1 + 8 structure according to the present invention.

[Explanation of symbols]

 1,3 core filament 2,4 sheath filament dc core wire diameter Lc core waveform amplitude Pc core waveform pitch

Claims (5)

[Claims] 1. A core comprising one steel filament and a sheath comprising six steel filaments arranged around the core, the core filament being corrugated, and the amplitude of the corrugation. The molding ratio Rc (= Lc / dc) represented by the ratio of Lc to the core wire diameter dc of the core filament is 0.12 ≦ Rc ≦ 1.5, and the corrugated pitch Pc is Assuming that the filament diameter is dc, 3.0 dc / 0.34 ≦ Pc ≦ 1
A steel cord for reinforcing a rubber article having a content of 0.0 dc / 0.34. 2. A core composed of one steel filament and a sheath composed of seven steel filaments arranged around the core, the core filament being corrugated, and the amplitude of the corrugated molding. The molding rate Rc (= Lc / dc) represented by the ratio of Lc to the core diameter dc of the core filament is 0.48 ≦ Rc ≦ 1.86, and the corrugated pitch Pc is Assuming that the filament diameter is dc, 3.0 dc / 0.34 ≦ Pc ≦
A steel cord for reinforcing rubber articles having a content of 10.0 dc / 0.34. 3. A core comprising one steel filament and a sheath comprising eight steel filaments arranged around the core, the core filament being corrugated, and the amplitude of the corrugation. The molding ratio Rc (= Lc / dc) represented by the ratio of Lc to the strand diameter dc of the core filament is 0.98 ≦ Rc ≦ 2.36, and the corrugated pitch Pc is Assuming that the filament diameter is dc, 3.0 dc / 0.34 ≦ Pc ≦
A steel cord for reinforcing rubber articles having a content of 10.0 dc / 0.34. 4. The carbon content is 0.80 to 0.85% by weight.
The steel cord according to any one of claims 1, 2, and 3. 5. The core filament diameter dc and the sheath filament diameter ds are substantially dc = ds.
The steel cord according to any one of 2, 3, and 4.