JP2002363873A - Steel cord for reinforcing rubber article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radial tire having excellent durability by achieving the production of belt ply-reinforcing layer in which strand wire cords comprising a number of steel cords that has uniform elongation and are folded in wavy form and the like and using the steel cords. SOLUTION: The steel cords comprises 2 or 3 layers having the central basic structure formed by twisting 3 filament together, but having no spiral in which the diameters of individual filaments are in a prescribed range, at least the twisting direction of the filament of the outer layer differs from the twisting direction of the filament of the adjacent inner layer, the cross section area Sc that is calculated based on the diameter of the steel cords, the sum ΣSf of the cross section areas Sf calculated based on the diameter Df of the filaments constituting the steel cords satisfies ΣSf/Sc>a prescribed value. The radial tire has the belt ply-reinforcing layer that is produced by continuously winding the strips of a plurality of steel cords covered with rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a steel cord for reinforcing rubber articles and a radial tire using the same.

[0002]

2. Description of the Related Art Conventionally, in order to suppress tire growth (internal pressure growth) and running growth and to improve tire durability, a carcass layer in which a number of cords substantially perpendicular to the tire equatorial plane are embedded is used. A belt layer having a parallel belt ply reinforcing layer in which a number of cords bent in a wavy or zigzag shape are embedded so as to be substantially parallel to an equatorial plane of a tire disposed radially outward thereof and embedded therein. There is known a large pneumatic radial tire having the following (for example, JP-A-2-81707).

[0003] This kind of radial tire has a parallel belt ply reinforcing layer arranged so as to be substantially parallel to the equatorial plane, so that internal pressure growth and running growth of the tire are suppressed and tire durability is improved. effective. However,
When the parallel belt ply reinforcement layer is a steel cord, if a cut is made to reach the parallel belt ply reinforcement layer by running the tire, water enters the steel cord from the cut part, and this moisture passes through the gap between the filaments and the steel There is a concern that the sound may propagate in the longitudinal direction of the cord, break the adhesion between the cord and the rubber, and cause separation to progress in the tire circumferential direction.

[0004] As a countermeasure, a so-called rubber penetration cord is provided in which a gap is previously provided between filaments in the steel cord so that rubber easily penetrates into the steel cord during vulcanization to suppress the propagation of moisture from the outside. Although application is conceivable, when a method of manufacturing a wavy or zigzag steel parallel belt using gears known in JP-A-64-075227 is used, the influence of a gap existing between filaments causes a problem. When the cord is caught in the gear, it is crushed or twisted in the radial direction, the wavelength and amplitude of the corrugation of each steel cord are not uniform, and the steel parallel belt ply reinforcement layer that requires uniform elongation is required. It is difficult to obtain the tire, and there is a disadvantage in that the circumferential uniformity of the internal pressure growth and running growth of the tire is lost.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and it is an object of the present invention to provide a stranded wire comprising a large number of steel cords having a uniform elongation and bent in a wavy or zigzag shape. The present invention provides a steel cord that enables the production of a parallel belt ply reinforcement layer in which a cord is buried, and more particularly, to provide a (large) radial tire with higher durability using such a steel cord. It is in.

[0006]

Namely, the rubber article of the first invention
Steel cords for reinforcing products are, in particular, radial ties.
Wavy or zigzag used for belt ply reinforcement layer
A steel cord that is bent into a shape and embedded in rubber
And the central basic structure in which three filaments are twisted
It consists of a two-layer twisted structure without spiral having
The filament has a diameter of 0.15 to 0.30 mm,
At least the filament twist direction of the outer layer and the central basic structure
The twist direction of the filament is different and the steel cord
Diameter Dc ₁ Area Sc calculated based on₁ = (Dc₁ /
2)^Two × π and the filament that constitutes the steel cord
Diameter Df₁ Area Sf calculated based on₁ = (Df₁ 
/ 2)^Two × π Sum ΣSf₁ But ΣSf₁ / Sc₁ > 0.
68.
In this specification, “without spiral” or “non-spiral”
`` Spiral '' is sometimes added to the outermost circumference of the cord.
Has a so-called wrapping filament of spiral winding
Means no.

[0007] In terms of the twist pitch, preferably, the twist pitch Pc ₁ of the filament having the central basic structure,
The twist pitch Ps ₁ of the filament having the outer layer structure is 0.3
≦ Pc ₁ / Ps ₁ <0.8 This is a steel cord for reinforcing rubber articles satisfying the relation of: 0.8, particularly when used in a belt ply reinforcing layer of a radial tire, in terms of molding, a wave-like or zig-zag wavelength. λ ₁ , the wavy or zigzag half amplitude a ₁ is 2.0 × 10 ⁻² <2a ₁ / λ ₁
It is a steel cord for reinforcing rubber articles that satisfies the relationship of <7.0 × 10 ⁻² and 30 mm <λ ₁ <38 mm.

[0008] A steel cord for reinforcing a rubber article of the second invention.
Is the belt ply strength of the radial tire as in the first invention.
Bent in a wavy or zigzag shape used for
Steel cord to be buried in
Spiral with a central basic structure with twisted parts
Consisting of a three-layer stranded structure with no filament, the diameter of each filament
Is 0.12 to 0.23 mm, and at least the outer layer
Filament twist direction and filament of one inner layer from the outermost layer
The twist direction is different and the diameter Dc of the steel cord_Two To
Area Sc calculated based on_Two = (Dc_Two / 2)^Two × π
And the diameter Df of the filament constituting the steel cord
_Two Area Sf calculated based on_Two = (Df _Two / 2)^Two ×
Sum of πΣSf_Two But ΣSf_Two / Sc_Two > 0.70 Seki
It is characterized by satisfying the staff.

In terms of the twist pitch, it is preferable.
Or the twist pitch Pc of the filament having the central basic structure_Two ,
Twist pitch Ps of the outermost filament_Two Is 0.5 ≦
Pc _Two / Ps_Two Rubber article supplement that satisfies <0.8
Heavy duty steel cord, especially bells for radial tires
When used for the topply reinforcement layer,
For example, wavy or zigzag wavelength λ_Two , Wavy or zigzag
Half-amplitude a_Two Is 2.0 × 10^-2<2a_Two / Λ_Two <
7.0 × 10^-2, And 30 mm <λ_Two <38mm
It is a steel cord for reinforcing rubber articles that satisfies the relationship.

[0010] The third invention relates to a particularly large radial tire using the steel cord specified in the first invention, and includes a carcass layer in which a number of cords substantially perpendicular to the tire equatorial plane are embedded. A belt ply reinforcing layer disposed radially outside the carcass layer, arranged so as to be substantially parallel to the equatorial plane of the tire, and embedded with a number of steel cords bent in a wavy or zigzag shape. The reinforcing layer is formed by continuously winding a strip in which a plurality of steel cords are covered with rubber in a spiral manner, and the steel cord has the structure described above. It was done.

A fourth invention relates to a radial tire using the steel cord specified in the second invention, wherein a carcass layer in which a number of cords substantially perpendicular to the tire equatorial plane are embedded, A belt having a belt ply reinforcing layer in which a number of steel cords that are arranged radially outward of the layer and are arranged so as to be substantially parallel to the equatorial plane of the tire and that are bent in a wavy or zigzag shape are embedded. A reinforcing layer comprising a plurality of steel cords, each of which is formed by continuously winding a strip in which a plurality of steel cords are covered with rubber in a helical manner, wherein the steel cords have the above-described structure. is there.

Here, the radial tire according to the third aspect of the present invention will be further described. FIG. 1 shows a cross section of the radial tire in the tire width direction. In the radial tire of the illustrated example, at least two parallel belt ply reinforcing layers 2 are arranged radially outside a crown portion of a carcass 1 extending in a toroidal shape between a pair of beads. A belt ply reinforcement layer 3 in which steel cords arranged at a predetermined angle with respect to the equatorial plane of the tire are embedded, and two layers, three layers in the illustrated example, are arranged. A belt layer is constituted by the reinforcing layer 3 and a tread 4 is disposed thereon.

As shown in FIG. 2, the parallel belt ply reinforcing layer 2 is composed of a strip 6 in which a steel cord 5 plastically deformed in a wavy or zigzag manner by a plurality of gears, 11 in the illustrated example, is covered with rubber. The carcass 1 is spirally wound around the crown.

The requirements necessary for imparting uniform elongation to the parallel belt ply reinforcement layer plastically deformed in a wavy or zigzag manner with gears are that the wavelength and amplitude between the cords are uniform and that the cords are uniform. Are aligned. When the steel cord is bitten by gears and is shaped in a wave or zigzag shape, the cord is significantly crushed in the radial direction,
It has been found by the inventors of the present invention that, when the cords are unevenly twisted, the wavelengths and the amplitudes between the cords become uneven and a phase shift occurs.

[0015] As a countermeasure, a molding test using a twisted structure of various steel cords was carried out, and it was found that the smaller the gap between the filaments in the steel cord, the more uniform the wavelength and amplitude can be obtained. . Hereinafter, the present invention will be specifically described including the first invention. In the case of a two-layer twisted non-spiral steel cord having a central basic structure in which three filaments are twisted, the cross-sectional area Sc calculated based on the cord diameter Dc _{1 1 = (Dc 1/2)} 2 × π
When the cross-sectional area Sf ₁ that is calculated based on a straight径径Df ₁ of filaments constituting the code in Code = (Df _1/2)
The sum of ² × π ΣSf ₁ is ΣSf ₁ / Sc ₁ > 0.68,
It was found that when the following relationship was satisfied, a uniform molding was obtained.

The reason why the steel cord of the first invention has three central basic structures is as follows. In the case where the central basic structure is a single filament, when a typed corrugated pattern is received, the central basic structure has one central basic structure compared to a cord having a central basic structure in which a plurality of filaments are twisted. The filament is hard to stretch. For this reason, depending on the setting of the amplitude and wavelength of the steel cord of the reinforcing layer of the parallel belt ply, the tensile load ratio in the steel cord becomes high, and the cord is likely to be tensilely broken starting from this part. Is not preferred.

Next, when the central basic structure is two filaments, the cross section of the steel cord becomes elliptical and non-uniform in the longitudinal direction, and the steel cord is bitten by gears and becomes wavy or zigzag. It is not preferable that the cords are non-uniformly twisted at the time of molding, and the wavelengths and amplitudes between the cords tend to be non-uniform.

When the central basic structure is four filaments or more, the shape stability of the central basic structure is poor, so that when the steel cord is bitten by a gear and is shaped in a wavy or zigzag shape, the cord is easily crushed in the radial direction. This is not preferable because the wavelength and amplitude between the codes become non-uniform.

From the results of these considerations, it can be seen that the cross section of the steel cord is circular, the shape stability of the central basic structure is high, and the twisting rate of the interlayer filament tension in the steel cord can be easily adjusted by twisting. It has a basic structure.

The filament diameter range is from 0.15 to 0.3
The reason for setting 0 mmφ is to use a mold with uniform wavelength and amplitude.
Easy to use, thicker than 0.30mm
Belt reinforcement layer necessary for pneumatic radial tires
If made, 2a₁ / Λ ₁ Rolling tires when making a wave shape
Steel cord breakage due to fluctuating strain due to the expansion and contraction of the wavy shape when moving
More likely to occur, while filaments finer than 0.15 mm
The bending stiffness and breaking strength of steel cord are low.
Sufficient cut resistance and diameter growth suppression effect cannot be obtained.
You.

The steel cord in which the filaments of the outer layer and the filament of the central basic structure have different twisting directions is such that when the steel cord is plastically deformed in a wavy or zigzag manner by a gear, the steel cord is bitten at the tip of the gear. There is a gap between the outer filaments in the vicinity of the part, and rubber penetrates into the cord from this gap during tire vulcanization, so the gap between the filaments is filled with rubber, twisting it and suppressing the propagation of moisture, This is because the adhesion between the cord and the rubber is hardly broken, and the progress of separation in the tire circumferential direction is suppressed.

On the other hand, when a steel cord having the same direction twist is plastically deformed in a wavy or zigzag manner by a gear, the steel cord rotates in the direction in which the steel cord is twisted and unraveled in the vicinity of a portion bitten at the tip of the gear. Since it returns to the original state after passing through the gear, a gap is hardly generated between the outermost filaments.
For this reason, since it is difficult for the rubber to enter the gap between the filaments, the propagation of water cannot be sufficiently suppressed, the adhesion between the steel cord and the rubber is broken, and the separation tends to easily spread in the tire circumferential direction.

In the steel cord, the twist pitch of the outer layer is Ps ₁ , the twist pitch of the central basic structure is Pc ₁ ,
It is more preferable to satisfy 0.3 ≦ Pc ₁ / Ps ₁ <0.8. If Pc ₁ / Ps ₁ <0.3, the waveform of the inner layer is less likely to be attached to the outermost layer, and the wavelength and amplitude between the codes tend to be non-uniform.
In the case of 0.8 ≦ Pc ₁ / Ps ₁ , the inner layer structure is hardly stretched with respect to the outermost layer, so that the tensile load ratio in the steel cord is increased, and the steel cord is subjected to a tensile fracture starting from this portion. Is more likely to occur.

In the first invention, as shown in FIG. 3, when the wavy or zigzag wavelength of the code 8 is λ ₁ and the half amplitude of the wavy or zigzag is a ₁ , the code 8 in the tire is
Is 2.0 × 10 ⁻² <2a ₁ / λ ₁ <7.0 × 10 ⁻² ,
And 30 mm <λ ₁ <38 mm. When 2a ₁ / λ ₁ is 7.0 × 10 ⁻² or more, the effect of suppressing the internal pressure growth and running growth of the tire decreases, and when 2a ₁ / λ ₁ becomes 2.0 × 10 ⁻² or less. As a result, the steel cord is completely stretched due to the internal pressure and the running growth, and the tire buckles and is not formed in a normal shape, which is not preferable. When λ _{1 is set} to 38 mm or more, a ₁ must be increased, and the width of the parallel belt ply reinforcing layer increases, so that the belt strength decreases and more parallel belt ply reinforcing layers are used. This causes an increase in the weight of the tire and an increase in the gauge of the tread portion, which causes a reduction in tire durability. Further, when λ ₁ is less than 30 mm, a ₁ becomes too small, the wavelength and amplitude between the cords become uneven, and the phase shifts, so that the parallel belt ply reinforcement layer becomes non-uniform, and the tire The circumferential uniformity of the internal pressure growth and running growth is lost.

Next, referring to the second invention, the reason why the number of the central basic structures is three is the same as the reason described in the items 0016 to 0019.

The filament diameter range is from 0.12 to 0.2
The reason for setting 3 mmφ is the same as the reason described in item 0020. When a belt reinforcing layer necessary for a pneumatic radial tire is formed with a filament thicker than 0.23 mm, a corrugation of 2a ₂ / λ ₂ is formed. If made, steel cord breakage is likely to occur due to fluctuating strain due to the expansion and contraction of the wavy shape when rolling the tire. On the other hand, for filaments thinner than 0.12 mm, the bending rigidity and breaking strength of the steel cord will be low, and sufficient cut resistance This is because the effect of suppressing diameter growth cannot be obtained.

The steel cord in which at least the outermost filament and the inner filament of the one layer have different twisting directions is formed when the steel cord is plastically deformed in a wavy or zigzag shape by a gear. There is a gap between the outer layer filaments near the inserted part, and the rubber penetrates into the cord from the gap during tire vulcanization, so the gap between the filaments is filled with rubber, twisting it and suppressing the propagation of moisture Therefore, the adhesion between the cord and the rubber is hardly broken, and the progress of separation in the tire circumferential direction is suppressed. In addition, in some cases, rubber penetration does not reach the central basic structure because the steel cord of the third invention is twisted into three layers. However, moisture penetration into this part may lead to breakage of the adhesive between the cord and rubber. The time is long and does not become a big problem.

On the other hand, when a steel cord having the same direction twist or only the outer two layers is twisted in the same direction is plastically deformed in a wavy or zigzag manner by gears,
Significant problems can arise for the same reasons as described in the section.

In the above steel cord, the twist pitch of the outer layer is Ps ₂ , the twist pitch of the central basic structure is Pc ₂ ,
In this case, it is more preferable to satisfy 0.5 ≦ Pc ₂ / Ps ₂ <0.8. When Pc ₂ / Ps ₂ <0.5, the waveform of the inner layer is less likely to adhere to the outermost layer, and the wavelength and amplitude between the codes tend to be non-uniform.
In the case of 0.8 ≦ Pc ₂ / Ps ₂ , a problem occurs for the same reason as described in the section 0023.

Further, the wavelength of the wavy or zigzag shape is λ ₂ ,
Wavy or reasons for limiting when the zigzag of half amplitude was a ₂ is the same as the reason described for lambda _1, a ₁ in 0024 of paragraphs 1 invention.

[0031]

Next, the present invention will be described based on Examples and Comparative Examples.
As will be described in more detail, the present invention is limited to these examples.
It is not something to be done. (First invention / third invention): Table 1 below shows steel cords
Structure / wire diameter, twist direction, cord cross section Sc₁ , Filame
Total cross-sectional area₁ , Twist pitch, cord pitch
Ratio (Pc₁ / Ps ₁ ), Created by changing the value of
11 with a parallel belt ply reinforcement layer of 11 pulls
/70R22.5 size pneumatic radial tire
Code amplitude a₁ And wavelength λ₁ 2a₁ / Λ₁ ,wavelength
λ₁ , 2a₁ / Λ₁ Standard deviation, internal pressure growth and running growth
It shows the length of cut separation due to water and water propagation.
The code amplitude a in Example 1 and each comparative example₁ And waves
Long λ₁ 2a₁ / Λ₁ , Wavelength λ₁ , 2a₁ / Λ₁ Standard
Gap, internal pressure growth and running growth, cut by moisture propagation
Measurement of separation length, cord fatigue and cutability
The method is as follows.

(1) Standard deviation of 2a ₁ / λ ₁ , 2a ₁ / λ ₁ The coordinates of wave-shaped peaks and valleys of 10 wavelength strips of 11 steel cords taken out from the tire are measured and calculated. did.

(2) Internal pressure growth and running growth In the internal pressure growth, the internal pressure is increased from 9.8 × 10 ⁴ Pa to 7.105 ×
At 10 ⁵ Pa, the change in the tire circumference at the crown center was measured. Running growth is 5000k of QC drum
The change in the tire circumference at the crown center after m running was measured. The control (Comparative Example 1) was set to 100 for the internal pressure growth and the running growth, and the smaller the index, the better.

(3) Length of Cut Separation Due to Moisture Propagation After running a molded tire for 150,000 km, the maximum cut separation length of 11 strips taken out from the tire was measured.

(4) Cord Fatigue and Cutability After running the molded tire for 150,000 km on the ground, the eleven-stretched strip taken out from the tire is visually checked for breakability.
It was evaluated as “Yes”.

[0036]

[Table 1]

Embodiment 1 is an example of a steel cord based on the first invention.

In Comparative Example 1, the twist direction of Example 1 was the same direction, and since no gap was formed between filaments, rubber did not penetrate into the steel cord, and the cut separation length was increased. I have.

In Comparative Example 2, one of the outermost filaments of Example 1 was removed, but ΔSf ₁ / Sc ₁ <0.68
Therefore, the standard deviation of 2a ₁ / λ ₁ is large, suggesting that the wavelength and the amplitude are largely dispersed.

In Comparative Example 3, the wire diameter of Example 1 was increased, and since the filament diameter Df ₁ > 0.30 mmφ, the cord fatigue property was reduced and the filament was broken.

In Comparative Example 4, the filament diameter of Example 1 was reduced. Since the filament diameter Df ₁ <0.15 mmφ, the internal pressure growth and running growth were large, and the filament was broken by cutting.

In Comparative Example 5, the core twist pitch of Example 1 was shortened, and since Pc ₁ / Ps ₁ <0.3, 2a ₁ /
The standard deviation of lambda ₁ is large, suggesting that variations in the wavelength and amplitude have Oki.

In Comparative Example 6, the core twist pitch of Example 1 was increased, and since Pc ₁ / Ps ₁ > 0.8, the tensile load ratio of the core to the tensile input of the steel cord was high, and filament breakage occurred. ing.

In Comparative Example 7, the molding wavelength was short and 2a ₁ /
for λ ₁ is large, the internal pressure growth and driving growth is large.

In Comparative Example 8, the molding wavelength was long and 2a ₁ /
for λ ₁ is small, it will be stretched a steel cord in the internal pressure growth and driving growth, has caused a filament break.

(Second invention / fourth invention): Next, the second invention
-The fourth invention will be described based on Example 2 and Comparative Example.
You. Table 2 below shows the steel cord structure, wire diameter, and twisting method.
Direction, cord cross section Sc_Two , Filament cross section sum ΣS
f_Two , Twist pitch, cord pitch ratio (Pc_Two / Ps
_Two ) Is created by changing the value of
445 / 65R22 with row belt ply reinforcement layer applied.
Cord vibration for 5 size pneumatic radial tires
Width a_Two And wavelength λ_Two 2a_Two / Λ_Two , Wavelength λ_Two , 2a_Two /
λ_Two Standard deviation, internal pressure growth and running growth, moisture propagation
Indicates the length of cut separation. In addition, in Example 1 and
And code amplitude a in each comparative example_Two And wavelength λ_Two 2a_Two 
/ Λ_Two , Wavelength λ_Two , 2a_Two / Λ_Two Standard deviation, internal pressure growth
And separation by cutting and running growth
Measurement method for length, cord fatigue and cutability is 0023 ~
As described in 0026.

[0047]

[Table 2]

Embodiment 2 is an example of a steel cord according to the second invention.

In Comparative Example 11, the twist direction was the same as that of Example 2, and since no gap was formed between the filaments, rubber did not penetrate into the steel cord, and the cut separation length was increased. I have.

Comparative Example 12 is the outermost layer filament of Example 2.
Although I missed two pieces, _Two / Sc_Two <0.7
2a for 0_Two / Λ_Two The standard deviation of
This suggests that the width varies widely.

In Comparative Example 13, the filament diameter of Example 2 was increased, and the filament diameter Df ₂ > 0.23 mmφ.
Cord fatigue is reduced, and filament breakage occurs.

In Comparative Example 14, the wire diameter of Example 2 was reduced, and since the filament diameter Df ₂ <0.12 mmφ,
Internal pressure growth / running growth is large, and filament breakage due to cutting occurs.

In Comparative Example 15, the twist pitch of the core and the first sheath of Example 2 was shortened, and Pc ₂ / Ps ₂ <0.
Because of 5, the standard deviation of 2a ₂ / λ ₂ is large, suggesting that the wavelength and the amplitude are largely dispersed.

In Comparative Example 6, the core twist pitch of Example 2 was increased, and since Pc ₂ / Ps ₂ > 0.8, the tensile load ratio of the core to the tensile input of the steel cord was high, and filament breakage occurred. ing.

In Comparative Example 17, the molding wavelength was short and 2a ₂
Since / λ ₂ is large, internal pressure growth and running growth are large.

Comparative Example 18 had a long wavelength of 2a ₂
Since / λ ₂ is small, the steel cord is completely stretched by the internal pressure growth and running growth, and the filament is broken.

[0057]

From the above results, the carcass layer comprising at least one carcass ply in which a large number of steel cords substantially perpendicular to the tire equatorial plane according to the second and fourth inventions are embedded, A parallel belt ply reinforcement layer which is arranged radially outside of the layer, is arranged so as to be substantially parallel to the equatorial plane of the tire, and has embedded therein a cord made of many steels bent in a wavy or zigzag shape. In a radial tire having a belt layer having: a parallel belt ply reinforcing layer in which a stranded wire cord made of a number of steels bent in a wavy or zigzag shape having a uniform elongation is embedded, and running is performed. Because the breakage between the steel cord and the rubber caused by moisture propagation into the steel cord based on the cut inside is reduced,
The separation in the tire circumferential direction can be suppressed, which is a great advantage in practical use.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a cross section in a width direction of a pneumatic radial tire.

FIG. 2 is a view showing a structure of a strip for forming a belt reinforcing layer.

FIG. 3 is an enlarged sectional view showing a main part of a belt reinforcing layer.

[Explanation of symbols]

1 Carcass 2 Reinforcement layer 3 Reinforcement layer 4 Tread 5 Waveform code 6, 7 Strip 8 Waveform code λ ₁ Waveform or zigzag wavelength of code a ₂ Waveform or zigzag half amplitude of code

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshikazu Kaneko 1340-3 Kohata, Yaita-shi, Tochigi F-term (reference) 3B153 AA12 AA15 AA39 BB20 CC52 FF16 GG05 GG13

Claims (8)

[Claims] 1. The belt ply reinforcement layer of a radial tire
Used to bend in a wavy or zigzag shape and embedded in rubber
Steel cord, and three filaments
A spiral with a twisted central basic structure
It has a two-layer twist structure, and each filament has a diameter of 0.
15 to 0.30 mm and at least the outer layer filament
Twist direction and filament twist direction of central basic structure
Is different, the diameter Dc of the steel cord₁ Is calculated based on
Cross section Sc₁ = (Dc₁ / 2) ^Two × π and steel
Diameter Df of the filament constituting the cord₁ Calculated based on
Cross section Sf₁ = (Df₁ / 2)^Two × π Sum ΣSf₁ 
But ΣSf₁ / Sc₁ > 0.68
And a steel cord for reinforcing rubber articles. 2. A twist pitch Pc ₁ of a filament having a central basic structure and a twist pitch Ps _{1 of} a filament having an outer layer structure.
The steel cord for reinforcing a rubber article according to claim 1, wherein a relationship of 0.3 ≦ Pc ₁ / Ps ₁ <0.8 is satisfied. 3. The wavy or zigzag wavelength λ ₁ and the wavy or zigzag half-amplitude a ₁ are 2.0 × 10 ⁻² <2a _1.
/ Λ ₁ <7.0 × 10 ⁻² and 30 mm <λ ₁ <38 m
The steel cord for reinforcing a rubber article according to claim 1, wherein the steel cord satisfies a relationship of m. 4. A belt ply reinforcement layer for a radial tire.
Used to bend in a wavy or zigzag shape and embedded in rubber
Steel cord, and three filaments
A spiral with a twisted central basic structure
It has a three-layer twist structure, and each filament has a diameter of 0.
12 to 0.23 mm and at least the outer layer filament
Twist direction and filament twist of one inner layer from the outermost layer
The diameter of the steel cord Dc_Two Based on
Calculated cross-sectional area Sc_Two = (Dc_Two/ 2)^Two × π and ste
Diameter Df of the filament constituting the wire cord_Two Based on
Calculated cross-sectional area Sf_Two = (Df_Two / 2)^Two × π sumΣ
Sf_Two But ΣSf_Two / Sc _Two Satisfies the relationship of> 0.70
A steel cord for reinforcing rubber articles. 5. A filament twist pitch Pc ₂ of one inner layer from the outermost layer, and a twist pitch Ps of a filament of the outermost layer.
_{2. The} steel cord for reinforcing a rubber article according to claim 1, wherein ₂ satisfies the relationship of 0.5 ≦ Pc ₂ / Ps ₂ <0.8. 6. A wavy or zigzag wavelength λ ₂ , and a wavy or zigzag single amplitude a ₂ is 2.0 × 10 ⁻² <2a _2.
/ Λ ₂ <7.0 × 10 ⁻² and 30 mm <λ ₂ <38 m
The steel cord for reinforcing a rubber article according to claim 1, wherein the steel cord satisfies a relationship of m. 7. A carcass layer in which a number of cords substantially perpendicular to the tire equatorial plane are embedded, and are arranged radially outside of the carcass layer and arranged to be substantially parallel to the equatorial plane of the tire. And a belt layer having a belt ply reinforcement layer in which a number of steel cords bent in a wavy or zigzag shape are embedded, wherein the reinforcement layer covers a plurality of steel cords with rubber. A radial tire, wherein the strip is wound continuously in a helical manner, and the steel cord is the steel cord for reinforcing rubber articles according to any one of claims 1 to 3. 8. A carcass layer in which a number of cords substantially orthogonal to the tire equatorial plane are embedded, and are arranged radially outside of the carcass layer and arranged to be substantially parallel to the equatorial plane of the tire. And a belt layer having a belt ply reinforcement layer in which a number of steel cords bent in a wavy or zigzag shape are embedded, wherein the reinforcement layer covers a plurality of steel cords with rubber. A radial tire, wherein the strip is wound continuously in a helical manner, and the steel cord is the steel cord for reinforcing rubber articles according to any one of claims 4 to 6.