JPH0892883A - Steel cord for reinforcing rubber article - Google Patents

Abstract

PURPOSE: To produce a steel cord for reinforcing a rubber article excellent in corrosion propagation resistance without deteriorating the cord strength in a steel cord of a [1+(n)] structure[(n) is 6-8] and a pneumatic tire reinforced with the steel cord. CONSTITUTION: This steel cord for reinforcing a rubber article is obtained by preforming a core filament into a waveform in the steel cord for reinforcing the rubber article in which one spiral filament 3 is arranged around sheath filaments 2 by a [1+(n)] structure [(n) is 6, 7 or 8]. In the steel cord, the preforming ratio R (=L/D) represented by the ratio of the amplitude L of the wavy preforming to the wire diameter (d) of the core filament is respectively 0.08<=R<=1.4 when (n) is 6; 0.45$ R<=1.8 when (n) is 7 and 0.95<=R<=2.3 when (n) is 8. Furthermore, the sheath filaments are non-twist ones.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel cord for reinforcing rubber articles. TECHNICAL FIELD The present invention relates to a steel cord for reinforcing a rubber article, which has improved heat resistance and corrosion resistance, and a pneumatic tire reinforced with the steel cord.

[0002]

2. Description of the Related Art Rubber of 1 + 6, 1 + 7 or 1 + 8 structure consisting of a core filament composed of one steel filament and a sheath filament composed of 6, 7 or 8 steel filaments arranged around the core filament. In the steel cord for article reinforcement,
In order to improve the permeability of rubber inside the cord, a certain corrugation is applied to the core filament to secure a certain gap between adjacent sheath filaments, thereby suppressing the corrosion propagation of moisture etc. And steel cord for reinforcing rubber articles having improved corrosion propagation resistance
It is disclosed in Japanese Patent Publication No. 86978. Among such steel cords for reinforcing rubber articles, one having a 1 + 6 structure is shown in FIG. 5 as an example.

Steel cords for reinforcing these rubber articles are
Since it has a high corrosion propagation property, when it is used as a reinforcing material for a rubber composite such as a tire, the durability of the rubber composite is improved and the service life can be greatly improved.

[0004]

The above-mentioned steel cord for rubber reinforcement has good permeability of rubber into the cord, but since the sheath filament is twisted, the cord strength peculiar to the twisted cord decreases. The problem was inevitable.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a steel cord for reinforcing rubber articles which does not cause a reduction in cord strength in a steel cord having a 1 + n structure (n is 6 to 8) and is excellent in corrosion propagation. It is to provide a pneumatic tire reinforced by a steel cord.

[0006]

As a result of intensive studies to solve the above problems, the inventor of the present invention has a 1 + n structure (n is 6 to 8) in order to improve the permeability of rubber into the cord. By setting the corrugation patterning ratio of the core filament of the steel cord within a predetermined range, and making the sheath filament non-twisted to prevent the strength from being reduced by twisting, and by providing the spiral filament to prevent the variation due to the non-twisting Found that
The present invention has been completed.

That is, according to the present invention, a core filament composed of one steel filament, a sheath filament composed of six steel filaments arranged around the core filament, and one core filament arranged around the sheath. In a steel cord for reinforcing a rubber article, the core filament is shaped in a corrugated form, and an amplitude L of the corrugated form is formed.
And the molding ratio R (= L / d) represented by the ratio of the wire diameter d of the core filament is in the range of 0.08 to 1.4, and the sheath filament is non-twisted. The present invention relates to a characteristic steel cord for reinforcing a rubber article.

Further, according to the present invention, a core filament composed of one steel filament, a sheath filament composed of seven steel filaments arranged around the core filament, and one sheath filament arranged around the sheath. In a steel cord for reinforcing a rubber article, the core filament is shaped in a corrugated form, and a shaping ratio represented by a ratio of an amplitude L of the corrugated shaping and a wire diameter d of the core filament. R
(= L / d) is within a range of 0.45 to 1.8, and the sheath filament is non-twisted, and relates to a steel cord for reinforcing a rubber article.

Further, according to the present invention, a core filament composed of one steel filament, a sheath filament composed of eight steel filaments arranged around the core filament, and one core filament arranged around the sheath. In a steel cord for reinforcing a rubber article, the core filament is shaped in a waveform, and the amplitude L of the waveform shaping is
The molding ratio R (= L / d) represented by the ratio to the wire diameter d of the core filament is in the range of 0.95 to 2.3, and the sheath filament is non-twisted. The present invention relates to a steel cord for reinforcing rubber articles.

Furthermore, the present invention relates to a pneumatic tire reinforced by any of the above steel cords for reinforcing rubber articles.

[0011]

In the steel cord for reinforcing a rubber article of the present invention, by making the sheath filament untwisted,
It is possible to prevent a decrease in cord strength caused by twisting. The sheath filament, which may occur due to untwisting, can be prevented by the spiral filament.

Further, in the present invention, 1 + 6 + 1, 1
For the + 7 + 1 and 1 + 8 + 1 code structures, FIG.
It is necessary that the shaping ratio R (= L / d), which is represented by the ratio of the waveform shaping amplitude L of the core filament to the wire diameter d, satisfies the following conditions. When the number of sheath filaments is 6: 0.08 ≦ R ≦ 1.4 When the number of sheath filaments is 7: 0.45 ≦ R ≦ 1.8 When the number of sheath filaments is 8: 95 ≦ R ≦ 2.3

If the molding ratio R of the core filament is less than the above range, the effect of dispersing the arrangement of the sea filaments, properly securing the sheath gap and allowing the rubber to penetrate into the cord is insufficient. That is,
When R is within the above range, sufficient rubber can be stably permeated into the steel cord after pressure vulcanization.

On the other hand, when R exceeds the above range,
If the tensile load is applied to the cord, stress will not be evenly applied to the cord, resulting in a decrease in cord strength.

The pitch P of the molding of the core filament is
Preferably, the following conditions are satisfied. 8.8d ≦ P ≦ 29.4d If it is smaller than 8.8d, the strength of the filament is reduced due to the load on the filament at the time of molding, while 29.4d
If it is larger, it becomes difficult for the rubber to penetrate into the inside of the cord.

In the present invention, the number of sheath filaments arranged around the core is set to 6 to 8 when the number is 5 or less, it is difficult to obtain sufficient cord strength, and when the number is 9 or more, the sheath filament is This is because the gap between the two becomes small, and it becomes difficult for rubber to penetrate into the cord.

The wire diameters of the core filament and the sheath filament are not particularly limited, but the reinforcing material of the pneumatic tire is preferably within the range of 0.1 to 0.5 mm. From the viewpoint of manufacturing cost, it is preferable that they have the same wire diameter.

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

The steel cord for reinforcing a rubber article of the present invention can be suitably used as a reinforcing material for a pneumatic tire, particularly for a large pneumatic radial tire.

[0020]

EXAMPLES Next, the present invention will be specifically described with reference to Examples and Comparative Examples. Various steel cords having a core filament diameter (d), a sheath filament diameter, a spiral filament diameter, a core filament type ratio (R), a core filament pitch, a sheath filament pitch, and a spiral filament pitch shown in Table 1 below were experimentally manufactured.

Among the code structures of the embodiment shown in Table 1, the 1 + 6 + 1 structure is shown in FIG. 1 and the 1 + 7 + 1 structure is shown in FIG.
And the 1 + 8 + 1 structure is shown in FIG. In the figure, 1 is a core filament, 2 is a sheath filament, and 3 is a spiral filament.

10 types of radial tires for trucks and buses of size 10.00R20 equipped with belts in which various steel cords were buried were manufactured, and the corrosion resistance and the cord strength of the belt cords taken out from each tire were examined. It was

For the corrosion propagation resistance, take out 100 mm of the belt cord with the rubber covered from the tire, coat the side surface with a silicone sealant, and immerse one end of the cord in a 10% NaOH aqueous solution to form an aqueous solution only from the cut surface. And then immersed for 24 hours, pinch the rubber with pliers and peel it off, and make the exposed metal part the corrosion propagation part,
The length (mm) was evaluated. The results obtained are also shown in Table 1 below.

[0024]

[Table 1]

In the steel cords of 1 + 6 + 1 structure of Examples 1 to 3, there was no reduction in cord strength,
Moreover, the corrosion propagation resistance is also good. On the other hand, in Comparative Example 1, since the molding ratio R of the core filament is smaller than 0.08, the corrosion propagation resistance is inferior at 100 mm.
On the other hand, in Comparative Example 2, since the molding ratio R is larger than 1.4, the cord strength is inferior at 198 kgf. Comparative Example 3 has a 1 + 6 structure and sheath filaments having a pitch of 1
It is a conventional steel cord twisted with 7 mm, but in this case, the cord strength is inferior to 199 kgf.

Example 4 is a steel cord having a 1 + 7 + 1 structure, and this cord has no deterioration in strength and has good corrosion propagation resistance. On the other hand, Comparative Example 4 is a conventional steel cord having a 1 + 7 structure and sheath filaments twisted at a pitch of 17 mm.
kgf and a decrease in strength due to the twist of the sheath were observed.

Example 5 is a steel cord having a structure of 1 + 8 + 1. This cord has no deterioration in strength and has good corrosion propagation resistance. On the other hand, Comparative Example 5 is a conventional steel cord having a 1 + 8 structure in which sheath filaments are twisted at a pitch of 17 mm, but this cord also shows a decrease in strength due to twisting of the sheath.

[0028]

As described above, in the steel cord for reinforcing rubber articles of the present invention, the 1 + n structure (n
6-8), the corrugated patterning ratio of the core filament of the steel cord is within a predetermined range, the sheath filament is non-twisted, and a spiral filament is provided around this, so that the cord strength due to the twisting of the sheath is increased. There is no deterioration, and the permeability of rubber inside the cord is good, corrosion propagation of moisture etc. is suppressed, that is, corrosion propagation resistance is improved. Therefore, this steel cord is used for rubber composites such as pneumatic tires. When used as a reinforcing material, the durability of the tire or the like can be improved and its service life can be significantly extended.

[Brief description of drawings]

FIG. 1 (a) is a cross-sectional view of a steel cord for reinforcing a rubber article, which is an example of the present invention having a 1 + 6 + 1 structure. (B) is a perspective view of a cross section of the steel cord.

FIG. 2 is a cross-sectional view of a steel cord for reinforcing a rubber article, which is an example of the present invention having a 1 + 7 + 1 structure.

FIG. 3 is a cross-sectional view of a steel cord for reinforcing a rubber article, which is an example of the present invention having a 1 + 8 + 1 structure.

FIG. 4 Amplitude L of a corrugated core filament
It is explanatory drawing which shows the relationship with and the wire diameter d.

FIG. 5 is a cross-sectional view of a conventional steel cord for reinforcing a rubber article having a 1 + 6 structure.

[Explanation of symbols]

 1 core filament 2 sheath filament 3 spiral filament

Claims (4)

[Claims] 1. A core filament composed of one steel filament, a sheath filament composed of six steel filaments arranged around the core filament, and one spiral filament arranged around the sheath. In a steel cord for reinforcing a rubber article, the core filament is shaped in a corrugated form, and a forming ratio R (= L is represented by a ratio of an amplitude L of the corrugated form and a wire diameter d of the core filament. / D) is 0.08 to 1.
Steel cord for reinforcing rubber articles, characterized in that it is within the range of 4 and the sheath filament is non-twisted. 2. A core filament composed of one steel filament, a sheath filament composed of seven steel filaments arranged around the core filament, and a spiral filament arranged around the sheath. In a steel cord for reinforcing a rubber article, the core filament is shaped in a corrugated form, and a forming ratio R (= L is represented by a ratio of an amplitude L of the corrugated form and a wire diameter d of the core filament. / D) is 0.45-1.
Steel cord for reinforcing rubber articles, characterized in that it is within the range of 8 and the sheath filament is non-twisted. 3. A core filament composed of one steel filament, a sheath filament composed of eight steel filaments arranged around the core filament, and one spiral filament arranged around the sheath. In a steel cord for reinforcing a rubber article, the core filament is shaped in a corrugated form, and a forming ratio R (= L is represented by a ratio of an amplitude L of the corrugated form and a wire diameter d of the core filament. / D) is 0.95 to 2.
Steel cord for reinforcing rubber articles, characterized in that it is within the range of 3 and the sheath filament is non-twisted. 4. A pneumatic tire reinforced with the steel cord for reinforcing a rubber article according to claim 1.