JP3040026B2 - Steel cord - Google Patents

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, and more particularly to a steel cord which suppresses the propagation of corrosion due to moisture and the like and improves the corrosion propagation resistance. About steel cord.

[0002]

2. Description of the Related Art In a product reinforced with a steel cord, there is a problem that a durable life of the product is shortened due to corrosion of a steel filament due to moisture entering the product.

For example, in a steel cord used for a tire belt, if there is a cavity in the steel cord, if the tire is injured enough to reach the tread or the belt, moisture that has penetrated the belt may cause the cavity in the steel cord to be removed. This spreads along the longitudinal direction of the cord, and as a result, rust caused by moisture is also diffused and the adhesive strength between the rubber and the steel cord at that portion is reduced, which eventually causes the separation phenomenon.

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

First, Japanese Patent Publication Nos. 62-2164 and 60
JP-A-49421 discloses that an excessively large mold gives a gap to a filament of a cord. However, there is a disadvantage that it is difficult to maintain the gap and the effect is affected by handling in the tire manufacturing process.

On the other hand, Japanese Patent Application Laid-Open No. 1-175503 discloses a technique for improving a cord structure and securing a gap between filaments, irrespective of the type of filament, and discloses one core filament and six sheath filaments. Steel cord consisting of
No. 8204 and Japanese Unexamined Patent Publication No.
A two-layer twisted steel cord comprising a core made of two metal strands and a sheath filament disposed around the core is disclosed.

In particular, the 1 + 6 cord disclosed in Japanese Patent Laid-Open Publication No. 1-175503 can be twisted in one step, which is advantageous in productivity. However, in the disclosed 1 + 6 cord, the core filament diameter is made larger than the sheath filament diameter to secure a certain gap or more between adjacent sheath filaments so that the rubber penetrates into the inside. In particular, when the sheath filaments are biased, the rubber does not penetrate on the side where the sheath filaments are in close contact with each other, and when applied to truck tires running on severe high moisture bad roads, sufficient corrosion resistance propagation I can not get the nature. Further, there are problems such as an increase in cord weight and a decrease in productivity.

In the 1 + 5 structure as disclosed in Japanese Patent Application Laid-Open No. 56-131404, the core filament diameter is smaller than the sheath filament diameter. Since the rigidity is weakened, the effect of corrugation is reduced, and even when the molding ratio is increased to improve the permeability of rubber, there is a disadvantage that the strength is reduced.

[0009]

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

[0010]

Means for Solving the Problems The present inventor has conducted intensive studies to solve the above-mentioned problems, and as a result, has obtained 1 + 6, 1+
By using a filament having substantially the same diameter as the sheath filament as the core filament of the steel cord having a 7, 1 + 8 structure, and applying an appropriate corrugation to the core filament, sufficient rubber can be applied to the steel cord after pressure vulcanization. The present inventors have found that they can be stably penetrated, and have completed the present invention.

That is, the present invention provides: (1) a core made of one steel filament;
A sheath made of six steel filaments is provided around the core, and the core filament is shaped in a waveform, and is expressed by a ratio of an amplitude Lc of the waveform shaping to a wire diameter dc of the core filament. Molding rate Rc
(= Lc / dc) is 0.12 ≦ Rc ≦ 1.5 and the pitch Pc of the corrugation is 3.0 dc / 0.34 ≦ Pc ≦ 10, where the core filament diameter is dc.
0 dc / 0.34, a steel cord for reinforcing rubber articles,

(2) A core made of one steel filament and a sheath made of seven steel filaments arranged around the core, wherein the core filament is corrugated, and the core filament is corrugated. Amplitude Lc
And the shaping ratio Rc (= Lc / dc) expressed by the ratio of the core filament filament diameter dc to 0.48 ≦ Rc ≦ 1.
86 and the pitch Pc of the waveform shaping is 3.0 dc / 0.34 ≦ given that 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, wherein the core filament is formed into a corrugated shape. Amplitude Lc
And the elementing diameter Rc (= Lc / dc) expressed by the ratio of the element diameter dc of the core filament to 0.98 ≦ Rc ≦ 2.
36 and the pitch Pc of the waveform shaping is 3.0 dc / 0.34 ≦, where the core filament diameter is dc.
A steel cord for reinforcing rubber articles, wherein Pc ≦ 10.0 dc / 0.34,

(4) The 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 a weight percent.

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

Hereinafter, the present invention will be described in detail. In the present invention, the core filament is shaped into a waveform. It is important that this waveform be a waveform having a specific range of amplitude and pitch by using steel cords of 1 + 6, 1 + 7, and 1 + 8 structures, thereby securing a gap for rubber penetration between the sheath filaments. However, since the waveform is formed with good productivity and low cost, and when the core filament is formed into a corrugated shape, the cord itself becomes a flat cord, which can prevent an increase in cord thickness due to the shaping.
The thickness of the rubber layer can be reduced by making the gauge thinner. Further, since the rubber has good permeability, there are advantages such as an increase in corrosion resistance.

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

When the number of sheath filaments is 6, ie, 1
In the case of the +6 structure, the core filament molding rate Rc
(= Lc / dc, where Lc is the amplitude of the waveform, and dc is the diameter of the core filament wire), and 0.12 ≦ Rc ≦ 1.5.
If Rc is less than 0.12, the effect of dispersing the sheath arrangement, properly securing the sheath gap, and penetrating the rubber into the cord is insufficient, and if Rc exceeds 1.5, the cord properties are poor. This is because, when a tensile load is applied, the stress is not applied uniformly and the cord strength is reduced.

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

When the number of sheath filaments is eight, ie, 1
In the case of the +8 structure, the core filament molding rate Rc
Is set to 0.98 ≦ Rc ≦ 2.36. When Rc is smaller than 0.98, there is the same disadvantage as when Rc <0.12 when 1 + 6, and when Rc exceeds 2.36, it is the same as when Rc> 1.5 when 1 + 6. There are drawbacks.

The corrugated patterning pitch Pc of the 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 larger than 10.0 dc / 0.34, the effect of dispersing the sheath arrangement, properly securing the sheath gap, and permeating the rubber into the cord is insufficient.
Is smaller 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 the uniform load is applied to the core filament and the sheath filament during the tensile load on the cord. Without taking
Insufficient code strength.

When the strength of the rubber composite is secured and its weight is reduced as a reinforcing material, 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.

When the diameter of the core filament is smaller than the diameter of the sheath filament, the interval between the sheath filaments becomes narrower, rubber hardly enters, and the rigidity of the core becomes weaker, so that the effect of molding is reduced. When the core filament diameter is larger than the sheath filament diameter, there are problems such as an increase in cord weight and a decrease in productivity. Therefore, in order to increase the productivity in the manufacturing process,
It is preferable that the core filament diameter dc and the sheath filament diameter ds are substantially the same.

[0024]

The present invention will be described more specifically with reference to the following examples and comparative examples, but the present invention is not limited to these examples. A steel cord having a core filament diameter dc, a sheath filament diameter ds, a cord structure, a core waveform shaping rate Rc, a core waveform pitch Pc, and a sheath twist pitch Ps described in Tables 1, 2, 3, and 4 was embedded. Size 10.00R2 with belt
19 prototypes of 0 radial tires for trucks and buses were manufactured, and the corrosion propagation resistance (separation resistance) and the cord strength of each tire were examined. Table 1 shows the results.
Table 4 below.

For the corrosion propagation resistance, 100 mm of a belt cord with the rubber covered from the tire was taken out, and one side of the cord was covered with a silicone sealant after one end of the cord.
It was immersed in a 0% NaOH aqueous solution to infiltrate the aqueous solution only from the cut surface, and then immersed for 24 hours. The rubber was pinched off with pliers, and the portion where the metal was exposed was used as a corrosion propagation portion, and the length (mm) was evaluated. .

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

[0029]

[Table 4]

In Comparative Example 1, the core mold coverage was less than 0.12, and the corrosion propagation resistance was as poor as 100 mm. Comparative Example 2
Shows that when the pitch Pc of the core waveform is smaller than 3.0 dc / 0.34, the cord strength is inferior to 182 kgf. Comparative Example 3 has a core strength of 180 kgf, which is inferior to that of the case in which the core mold ratio is larger than 1.5. Comparative Example 4 has a poor corrosion propagation resistance of 100 mm when the pitch Pc of the core waveform is larger than 10.0 dc / 0.34. In Comparative Examples 5 and 6, none of the core filaments was corrugated, and the corrosion propagation resistance was poor. Comparative Example 7 is a case where the core shaping ratio is larger than 1.5 and the core and the sheath are 0.23 mm strands, but the cord strength is inferior to 80 kgf. Comparative Example 8
In the case of the 1 + 7 structure and the core mold ratio is smaller than 0.48, the corrosion propagation resistance is inferior. Comparative Example 9 has a 1 + 8 structure,
When the core mold ratio is less than 0.98, the corrosion propagation resistance is poor.

[0031]

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

[Brief description of the 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 (having a large core diameter and no molding).

FIG. 3 is a cross-sectional view of a core formed into a waveform according to the present invention on a corrugated surface, and 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 amplitude of core waveform Pc pitch of core waveform

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) D07B 1/00-9/00

Claims (5)

(57) [Claims] 1. A core comprising a steel filament and a sheath comprising six steel filaments disposed around the core, wherein the core filament is corrugated, and the amplitude of the corrugation is provided. The shaping ratio Rc (= Lc / dc) represented by the ratio of Lc to the element wire diameter dc of the core filament is 0.12 ≦ Rc ≦ 1.5, and the pitch Pc of the corrugated shaping is equal to the core. Assuming that the filament diameter is dc, 3.0 dc / 0.34 ≦ Pc ≦ 1
A steel cord for reinforcing rubber articles having a ratio of 0.0 dc / 0.34. 2. A core comprising a steel filament and a sheath comprising seven steel filaments disposed around the core, wherein the core filament is shaped into a waveform and the amplitude of the waveform shaping. The shaping ratio Rc (= Lc / dc) represented by the ratio of Lc to the element wire diameter dc of the core filament is 0.48 ≦ Rc ≦ 1.86, and the pitch Pc of the waveform shaping is equal to Assuming that the filament diameter is dc, 3.0 dc / 0.34 ≦ Pc ≦
A steel cord for reinforcing rubber articles of 10.0 dc / 0.34. 3. A core comprising a steel filament and a sheath comprising eight steel filaments disposed around the core, wherein the core filament is corrugated, and the amplitude of the corrugation is provided. The shaping ratio Rc (= Lc / dc) expressed by the ratio of Lc to the strand diameter dc of the core filament is 0.98 ≦ Rc ≦ 2.36, and the pitch Pc of the waveform shaping is equal to Assuming that the filament diameter is dc, 3.0 dc / 0.34 ≦ Pc ≦
A steel cord for reinforcing rubber articles of 10.0 dc / 0.34. 4. A carbon content of 0.80 to 0.85% by weight
The steel cord according to any one of claims 1, 2, and 3, wherein 5. The method according to claim 1, wherein 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.