JP3177382B2 - Tire reinforcement cord and pneumatic tire using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention can reduce the thickness of a cord while securing necessary bending rigidity and compressive rigidity.
The present invention relates to a tire reinforcing cord useful for weight reduction and a pneumatic tire using the same.

[0002]

2. Description of the Related Art A pneumatic tire having a radial structure in which a tread portion is reinforced with a tough belt layer is frequently used in accordance with an increase in speed and performance of a vehicle. Usually has a plurality of steel filaments twisted together, for example, 1 × 3, 1 ×
A so-called steel cord having four structures or the like is widely used.

[0003] However, in recent years, in order to improve the fuel efficiency and the kinetic performance of vehicles, it is strongly desired to reduce the weight of tires.
In particular, in the case of a belt layer having a relatively large proportion of the tire weight, a non-metallic material having a small specific gravity such as an aromatic polyamide fiber is used instead of a steel cord.

[0004]

However, the cord using the non-metallic material has a problem in that the bending rigidity and the compressive rigidity are insufficient, and the steering stability, abrasion resistance, noise and the like are deteriorated.

[0005] In addition, as shown in FIG. 5, EP-A-492682 discloses that two to seven steel core filaments F1 aligned parallel to each other in the same plane.
Are bundled with a wrapping filament F2.

In this method, although the thickness of the cord can be reduced and the weight of the tire can be reduced, contact pressure acts between adjacent filaments because the cords are bundled by wrapping filaments. It is inferior in durability such as inducing wear damage. Also, since each filament is arranged independently, the bending stiffness of the cord does not greatly exceed the sum of the bending stiffness of each filament,
There is also a problem that the bending rigidity is insufficient and the wrapping filament unnecessarily increases the cord weight and the cord thickness.

The present invention is based on intermittent bonding between filaments aligned in parallel in the same plane, and greatly reduces the thickness of a cord while exhibiting high bending rigidity and compressive rigidity. It is an object of the present invention to provide a reinforcing cord for a tire and a pneumatic tire using the same.

[0008]

In order to achieve the above object, a first invention of the present application is to arrange two to six steel filaments side by side in the same plane without twisting. Adhering and adhering adjacent filaments intermittently and adjusting the diameter of each filament to 0.1
This is a tire reinforcing cord having a range of 5 to 0.3 mm.

In a second aspect of the present invention, there is provided a carcass folded from a tread portion to a sidewall portion around a bead core of a bead portion, and a reinforcing cord disposed radially outside the carcass and inside the tread portion and topped with a reinforcing cord. The reinforcing cord includes at least one reinforcing ply embedded in rubber, and the reinforcing cord draws two to six steel filaments side by side in the same plane without twisting. A pneumatic tire having a band shape in which aligned and adjacent filaments are intermittently bonded, the diameter of each filament is in the range of 0.15 to 0.3 mm, and the thickness of the reinforcing ply is 1 mm or less.

[0010]

The reinforcing cord is formed of filaments aligned in parallel on the same plane. For this reason, the thickness of the cord can be reduced until it becomes equal to the diameter of the filament. Even when a filament having a diameter D of 0.15 to 0.3 mm is used, the thickness of the ply can be maintained at 1 mm or less. Thus, the weight of the tire can be significantly reduced.

In addition, since the filaments adjacent to each other are intermittently bonded, the filaments can be restrained to each other, and the bending rigidity can be greatly improved while maintaining characteristics such as tensile elasticity as a cord. Becomes possible.

Further, since the filaments are intermittently bonded by bonding, no contact pressure acts between the filaments, thereby reducing the abrasion damage of the filaments during bending deformation and greatly increasing the durability of the cord. Further, a minute gap can be provided between the filaments. At this time, the durability of the cord is further improved.

[0013]

An embodiment of the present invention will be described below with reference to the drawings. In the figure, a pneumatic tire 1 has a tread portion 2,
The tire includes a sidewall portion 3 extending inward in the tire radial direction from both ends of the tread portion 2 and a bead portion 4 located at the radially inner end of each sidewall portion 3. It is formed as a flat radial tire having an aspect ratio of 80% or less, for example, 65%.

Further, the pneumatic tire 1 includes the bead portion 4,
Between the tread portion 2 and the side wall portion 3, a carcass 6 whose both ends are folded around the bead core 5 of the bead portion 4 is bridged, and is radially outside of the carcass 6 and inside the tread portion 2. , A tough reinforcing layer 7 is wound.

The carcass 6 has at least one carcass cord arranged at an angle of 75 to 90 degrees with respect to the tire equator.
The carcass ply 6A has a hard portion extending from the bead core 5 to the outside in the tire radial direction between the toroidal body portion 6a and the folded portions 6b at both ends of the carcass 6. A bead apex 8 is provided to reinforce from the bead portion 4 to the sidewall portion 3 and increase the tire lateral rigidity.

In the present embodiment, the carcass 6 is formed of, for example, one carcass ply 6A using polyester fibers. As the carcass cord, other organic fiber cords such as nylon, rayon, and aromatic polyamide are preferably used. An ordinary metal cord in which a steel filament or the like is twisted according to the required tire performance can be used.

The reinforcing layer 7 is a so-called belt layer formed of at least one or more reinforcing ply 7A in the present embodiment, which is placed on the carcass 6, and an outer reinforcing ply 7B disposed outside the reinforcing ply 7A. Thus, the tread portion 2 is reinforced almost all the width with a tag effect.

Each of the reinforcing plies 7A and 7B is a reinforcing cord 1
0 is arranged at an angle of 10 to 30 degrees with respect to the tire equator in a sheet form in which tread rubber 12 embeds a cord array 11. In this example, the reinforcing plies 7A and 7B They are arranged in different directions so as to intersect with each other.

As shown in FIGS. 2 and 3, the reinforcing cord 10 is formed by twisting two to six steel filaments 13 having a diameter D of 0.15 to 0.3 mm without twisting. It is formed in a flat band shape in which the adjacent filaments 13 are intermittently adhered between the adjacent filaments 13 by being twisted and arranged side by side in the same plane. As a result, each of the reinforcing plies 7A and 7B has a thickness t of 1.0 mm or less.
Preferably, it is set to 0.8 mm or less.

In the present embodiment, the reinforcing cord 10 is composed of four filaments 13. The filaments 13 are arranged in parallel with a small interval d, and are bonded by using welding means such as spot welding. Is done. In addition, as the bonding, for example, an adhesive means using a thermosetting adhesive, an alloy adhesive, or the like may be employed.

As described above, since the reinforcing cords 10 bond the filaments 13 by bonding, a restraining force acts between the filaments, and the bending rigidity is greatly improved.

The pitch length of the intermittent bonding, that is, the pitch length L of the bonding portion K between the filaments 13
Is preferably 30 to 70 times the diameter D of the filament 13, and the bonding length KL of each bonding portion K is preferably not more than twice the diameter D. When the pitch length is smaller than 30D and when the bonding length KL is larger than 2D, the characteristics as a cord cannot be expected. Conversely, when the pitch length L exceeds 70D, the effect of improving the bending rigidity is not improved. Will be enough. As shown in FIG. 4, the bonding is performed by displacing the bonding portion K between adjacent filaments on one side and the bonding portion K between adjacent filaments on the other side in the axial direction. Can be dispersed, but from the viewpoint of maintaining the characteristics as a cord, the adhesive portion K is
As shown in FIG. 3, it is preferable to form them side by side.

The distance d between the filaments 13 is preferably 0.2 to 0.3 times the diameter D. When the distance d is smaller than 0.2D, the filaments 13 are deformed when the tire is deformed. There is a tendency for durability to decrease, such as in contact with each other, causing abrasion. Conversely, when the distance d is larger than 0.3D, the cord width becomes excessively large, and the number of plies needs to be increased, for example, the number E of filaments to be described later becomes insufficient, which hinders weight reduction.

In order to obtain a lightweight and sufficient strength, the reinforcing cord 10 has a strength of the filament 13 of 200 kg /.
mm ² or more.

In order to make the belt layer function effectively, the number E of filaments to be driven per 5 cm width of the reinforcing ply is set to 100 to 240 filaments / 5 cm.
^{3. The} filament density (S × E) obtained by multiplying the cross-sectional area S (unit: mm ² ) of the filament 13 by the number of shots E is 4.
It is set to 78 or more. The filament density is 4.
When it is smaller than 78, the handling stability and abrasion resistance are reduced, such as insufficient tread rigidity. Therefore, in order to enhance the performance, the filament density is set to 7.0 or more, more preferably 7.3 or more.

Further, in the reinforcing plies 7A and 7B, it is preferable that the interval a between the adjacent reinforcing cords 10 is 0.75 to 0.95 times the diameter D of the filament, and when the interval a is smaller than 0.75D. In addition, the rubber gauge between the cords is insufficient, and the cords are easily loosened due to the shearing force acting between the cords. When the distance a is larger than 0.95D, the filament density is reduced, and as a result, the tread rigidity becomes insufficient, and the steering stability and the wear resistance are reduced.

The reinforcing cord 10 can be used as a breaker cord of a breaker layer in a tire having a bias structure. In such a case, the reinforcing cords are arranged at an angle of 30 to 40 degrees with respect to the tire equator.

(Specific Example) Radial tires having the structure shown in FIG. 1 and having a tire size of 185 / 65R14 are prototyped based on the specifications shown in Table 1, and the weight, wear resistance, steering stability and noise of each test tire are shown. Was compared with Conventional Tire 1 and Conventional Tire 2.

The steering stability was measured by a five-point method based on the driver's sensory evaluation of the driving stability when the tire was mounted on a passenger car (1600 cc, FF vehicle) under the conditions of standard rim and standard internal pressure, and the vehicle was driven on a test course. Was rated. The average is 3 and the larger the value, the better.

The noise performance was measured by a coasting test specified in JASOC606. Using the passenger car, the vehicle was coasted on a straight test course at an engine-off state with a passing speed of 55 km / h, and was moved laterally from the traveling center by 7 km. Passing noise was measured by a stationary microphone installed at a height of 1.2 m from the road surface at a distance of 0.5 m, and the maximum level at that time was shown in dB (A).

[0031]

[Table 1]

[0032]

Since the present invention is constructed as described above, the thickness of the cord can be reduced while securing the required bending stiffness and compression stiffness. The tire can be reduced in weight while maintaining stability and noise.

[Brief description of the drawings]

FIG. 1 is a sectional view of a tire showing one embodiment of the present invention.

FIG. 2 is an enlarged perspective view showing a part of the reinforcing ply.

FIG. 3 is a plan view showing the reinforcing cord.

FIG. 4 is a plan view showing another example of the reinforcing cord.

FIG. 5 is a plan view of a cord for explaining a conventional technique.

[Explanation of symbols]

 2 Tread 3 Sidewall 4 Bead 5 Bead core 6 Carcass 7 Reinforcement layer 7A, 7B Reinforcement ply 10 Reinforcement cord 13 Filament

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-63-240402 (JP, A) JP-A-4-95506 (JP, A) JP-A-51-47702 (JP, A) JP-A-62 149929 (JP, A) JP-A-7-82679 (JP, A) JP-A-63-97404 (JP, A) JP-A-64-24603 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60C 9/00 B60C 9/18-9/20 D07B 1/06

Claims (6)

(57) [Claims] 1. A steel filament comprising two to six steel filaments,
Without twisting, the filaments are arranged side by side in the same plane, aligned in parallel, and the adjacent filaments are intermittently bonded, and the diameter of each filament is 0.15 to 0.3 mm.
Tire reinforcement cord in the range of 2. A carcass folded back from a tread portion to a side wall portion around a bead core of a bead portion, and a reinforcing cord disposed radially outside of the carcass and inside the tread portion, and a reinforcing cord is embedded in topping rubber. The reinforcing cord comprises at least one reinforcing ply, and the reinforcing cord has two to six steel filaments arranged side by side in a same plane without twisting so as to be aligned and parallel to each other. A pneumatic tire having a belt shape in which filaments are intermittently adhered, each filament having a diameter of 0.15 to 0.3 mm and a thickness of the reinforcing ply of 1 mm or less. 3. The pneumatic tire according to claim ² , wherein the filament has a strength of 200 kg / mm ² or more. 4. The pneumatic tire according to claim 2, wherein the reinforcing ply has a number of filaments E of 100 to 240/5 cm per 5 cm width of the reinforcing ply. 5. The reinforcing cord according to claim 1, wherein a distance d between adjacent filaments is 0.2 to 0.3 of a diameter D of the filament.
In addition to the doubled, the reinforcing ply is arranged such that a distance a between adjacent reinforcing cords is 0.75 to a diameter D of the filament.
3. The pneumatic tire according to claim 2, wherein said pneumatic tire is 0.95 times. 6. The reinforcing ply is characterized in that a filament density (S × E) obtained by multiplying a cross-sectional area S (unit: mm ² ) of the filament by a number E of the cords to be set is 4.78 or more. The pneumatic tire according to claim 4.