JPH11217779A - Material for reinforcing rubber product and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a pneumatic tire capable of avoiding the buckling of a belt under a very severe condition of using a tire by using a metal single wire having a cross section of an almost rectangular shape as a belt reinforcing material. SOLUTION: This pneumatic tire is obtained by using a metal single wire having an almost rectangular cross section satisfying the ranges of 0.5-10.0 mm width (longer diameter) (a) and 0.05-0.40 mm thickness (shorter diameter) (b) and also the relationship of a>=2b as a reinforcing material for a rubber product, and arranging a plurality of the above metal wires in a belt width direction in parallel as a belt reinforcing material of a pneumatic tire equipped with a belt and tread in a radial direction of a crown part of a carcass extending as toroidal between a left and right pair of bead parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rubber article reinforcing material used for rubber articles such as pneumatic tires and industrial belts, and a pneumatic tire using the reinforcing material as a belt reinforcing material.

[0002]

2. Description of the Related Art A belt for locking a carcass ply of a pneumatic radial tire extends along the equatorial plane of the tire or extends in a direction inclined with respect to the equatorial plane of the tire. Lumber is commonly used. Such a belt generally has a laminated structure in which a plurality of reinforcing members are covered with rubber and at least two layers of the obtained covering members are laminated.

Here, in order to improve the steering stability when the vehicle is running, it is advantageous to increase the cornering force generated in the direction perpendicular to the vehicle traveling direction with respect to the steering with a constant input. In order to increase the cornering force, it is necessary to increase the lateral slip deformation of the tread land portion that occurs in the contact area of the tire when the tire rolls. The amount of side slip deformation is a deformation caused by the cornering force of the belt supporting the tread land portion of the tire, that is, a deformation occurring in the belt ply shown in FIG. 1A in the direction along the surface of each layer of the belt shown in FIG. (Less than,
"In-plane bending deformation"). That is, in order to generate a large cornering force, it is preferable to suppress the in-plane bending deformation of the belt portion, and therefore, the ability to resist the in-plane bending deformation (hereinafter, referred to as “in-plane bending rigidity”) is high. Required.

[0004] In addition, in order to obtain excellent vibration riding comfort, it is advantageous to secure a contact area even with a slight unevenness of the road surface. Ability to resist deformation occurring in a direction perpendicular to the plane (hereinafter,
(Referred to as “out-of-plane bending stiffness”).

Therefore, it is necessary to optimize the bending stiffness required for a tire belt in different directions, in-plane and out-of-plane, respectively. Many proposals have been made for the structure of the reinforcing material because it is affected by the performance of the reinforcing material.

For example, a reinforcing material having a flat cross-sectional shape has a so-called anisotropy in which the bending rigidity is different depending on a bending direction. Therefore, the reinforcing material is applied to a tire belt such that its major axis extends in the belt width direction. By arranging, it is possible to reduce the out-of-plane bending stiffness while increasing the in-plane bending stiffness of the belt.

On the other hand, if the cross section of the reinforcing material is flattened, under extremely severe use conditions in which the vehicle repeatedly turns sharply, such as running on a so-called tortuous path over a long distance, depending on the thickness of the belt, depending on its thickness, The cord may be broken, and if the thickness is small, it is difficult to maintain a desired strength, so that the durability of the belt becomes a problem.

[0008] Regarding the durability of this belt,
In JP-A-200303, by flattening flat-section steel wires in parallel and coating them with unvulcanized rubber to form a flat plate,
Belt reinforcements have been proposed that avoid wear between steel wires and significantly extend tire life.

In Japanese Patent Application Laid-Open No. Sho 61-12989, carbon content: 0.65 to 0.90% by weight, tensile strength:
2.2 × 10 ⁵ psi or more and elongation at break: 1.0 to
It has been proposed to reduce tire tread wear and belt heating with rubber articles reinforced with cold worked flat steel wire cords in the range of 3.5%.

Further, in Japanese Patent Application Laid-Open No. 6-158565, a tire reinforcing steel cord in which a wire having a substantially track-shaped cross section is given a flat spiral shape having a substantially elliptical or substantially track-shaped contour is used. It has been proposed to improve not only the flexibility and elongation properties but also the rigidity of a steel wire.

[0011]

The tires proposed above do not cause a problem when traveling straight, but under extremely severe use conditions, that is, when traveling over a so-called meandering path over a long distance, the tires may be used. It has been found that frequent buckling of the belt during repeated sharp turns results in cord breakage. If the cord is frequently broken, the belt has a partial recess on the surface of the tread, causing abnormal wear on the tread. As a result, there is a problem that the life of the tire is shortened. In addition, if the wire is subjected to a habit, the productivity of the steel cord is greatly reduced, and the cost is increased.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a reinforcing member capable of avoiding disadvantages caused by flattening, particularly breakage caused by belt buckling under extremely severe tire use conditions, and a flattening member. It is another object of the present invention to provide a pneumatic tire that can enjoy improved belt performance by the reinforcing member.

[0013]

In order to solve the above-mentioned problems, a reinforcing material for a rubber article according to the present invention comprises a single metal wire having a substantially rectangular cross section and an elongation at break of 3.6% or more. It is characterized by the following.

The pneumatic tire according to the present invention is a pneumatic tire having a belt and a tread radially outside a crown portion of a carcass extending in a toroidal shape between a pair of right and left beads, wherein the belt has a substantially rectangular shape. A plurality of single metal wires having a cross section and a breaking elongation of 3.6% or more are arranged in parallel in the tire belt width direction. The relationship between the width (major axis) a and the thickness (minor axis) b of the cross section of the single metal wire preferably satisfies the relationship represented by the following formula, a ≧ 2b, and more preferably the width (major axis) a Is 0.5 to 10.0 mm, and the thickness (short diameter) b is in the range of 0.05 to 0.40 mm.

[0015]

FIG. 2 (a) shows a specific example of a single metal wire of a reinforcing material for a rubber article according to the present invention. The cross-sectional shape of the single metal wire 1 may be substantially rectangular, and may be, for example, an elliptical shape having no corners. That is, as shown in FIG. 2B, the cross section may be a single metal wire 2 having an oval cross section.

In such a single metal wire, the relation between the width (major axis) a and the thickness (minor axis) b of the cross section is preferably a
Those with ≧ 2b, more preferably with a ≧ 3b are advantageously suited as belt reinforcements for pneumatic tires. More specifically, it is preferable that the width a is 0.5 to 10.0 mm and the thickness b is 0.05 to 0.40 mm. When the width a is less than 0.5 mm, the in-plane bending stiffness of the belt becomes small, and no improvement in steering stability is observed. On the other hand, when the width a exceeds 10.0 mm, wire drawing workability is slightly reduced, and productivity is reduced. Will be brought. Similarly, when the thickness b is less than 0.05 mm, the wire drawing processability is slightly reduced, and the wire breaks during the wire drawing and the productivity is reduced. On the other hand, when the thickness b exceeds 0.40 mm, the bending input during tire running is reduced. As a result, the surface distortion caused by the above becomes large, and the belt cord breaking resistance is not improved. Further, the interval between the single metal wires is preferably 0.3 to 3.0 mm.

Further, the breaking elongation of the single metal wire of the reinforcing material for rubber articles of the present invention must be 3.6% or more, and preferably 4.0% or more. If the elongation at break is less than 3.6%, the belt cord breakage resistance is inferior to the conventional steel cord due to flattening of the single metal wire.
Generally, a metal single wire having a substantially rectangular cross section is manufactured by a roller rolling method in which a wire rod after die drawing is rolled with a roller (elongation at break: 1.0 to 3.5%), but the metal single wire of the present invention is manufactured. To do this, pull out the die, for example,
It is necessary to perform a heat treatment in a furnace maintained at 340 to 460 ° C. for a time during which a predetermined breaking elongation is obtained.

Further, the present invention applies the above-described single metal wire as a reinforcing material for rubber articles to, for example, a belt 3 of a pneumatic tire shown in FIG. In addition, it is possible to advantageously avoid breakage of the belt reinforcing material (metal wire), which is a problem under extremely severe use conditions such as repeated rapid turning of the vehicle. In addition, by applying a metal single wire having a substantially rectangular cross section to the belt, the out-of-plane bending stiffness of such a belt is reduced, so that the contact property against unevenness of the road surface is improved. Therefore, a tire having excellent steering stability and ride comfort can be obtained.

The pneumatic tire according to the present invention shown in FIG. 3 has a carcass 5 extending in a toroidal shape between a pair of right and left bead cores 4, and a two-layered carcass 5, which is disposed outside the crown of the carcass 5 in the tire radial direction. And a tread 6 disposed radially outward of the belt 3 in the tire radial direction.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. Examples 1 to 6, Conventional Examples and Comparative Examples 1 to 2 A 165SR13 size radial tire for a passenger car having a one-ply carcass and a two-belt ply structure shown in FIG. And a single metal wire having the conditions shown in Table 1 below were applied in such an arrangement that the axial direction of the single metal wire was inclined at 20 degrees with respect to the equatorial plane of the tire.

Further, as Comparative Examples 1 and 2, a single metal wire having a rectangular cross section but having a breaking elongation smaller than that specified in the present invention was used. Further, as a conventional example, a steel cord having a 1 × 3 structure shown in FIG. : 0.28 mm)
Each was applied to a tire belt in the same manner as described above under the conditions shown in Table 1 below.

Each of the obtained tires was tested for belt cord break resistance, steering stability and ride comfort, and each reinforcing material was tested for wire drawing workability. The test methods are as follows.

(1) Folding resistance of the belt cord After filling the tire with a specified internal pressure, the tire is mounted on an actual vehicle and the tire is driven at 60 kph
After running 20,000 km on a constant meandering path at m, the tire was dissected, reinforcing material was collected from the belt, the number of broken cords was measured, and the result was expressed as an index by the following equation. The smaller the index, the smaller the number of broken cords, indicating that the belt cord is more resistant to breakage. (Breaking resistance index of belt cord) = (number of folds in test tire) / (number of folds in conventional tire) × 100

(2) Maneuvering Stability One of the measures for maneuvering stability is belt rigidity. The cornering power (CP) obtained from this in the state of the tire is the cornering power (CP). In this test, a tire filled with an internal pressure of 190 kPa was mounted on a rim 4.50B, pressed against a drum having a diameter of 3 m with a load of 425 kg, and preliminarily driven at a speed of 30 km / h for 30 minutes. After the preliminary running, the internal pressure is readjusted, the cornering force is measured with the same speed, the same load, positive and negative slip angles, and the cornering power (CP) is calculated by the following equation.
I asked. CP = ｛CF (1 °) + CF (2 °) / 2 + CF (3
°) / 3 + CF (4 °) / 4 ° / 4 where CF (1 °), CF (2 °), CF (3 °) and CF (4 °) each have a slip angle of 1
It is the value of the cornering force at the time of degree, degree 2, degree 3, and degree 4. This C. P. Based on the values, the steering stability was expressed as an index by the following formula. The larger the index, the better the steering stability. (Driving stability index) = (CP value of test tire) /
(CP value of conventional tire) × 100

(3) Ride Comfort A protrusion having a width of 2 cm and a height of 1 cm was attached to one place on an iron drum having an outer diameter of 2 m, and a tire was pressed on the drum with a standard load to rotate the drum. did. The vertical vibration when the tire passes over the protrusion is measured by the accelerometer as the force of the tire mounting axis. From the waveform recorded here, the amplitude of the first cycle is determined as the number of hits, and The riding comfort index was determined from the equation. The smaller the index, the better the ride comfort. (Ride comfort index) = (Number of hits of test tire) / (Number of hits of conventional tire) × 100

(4) Wire drawing workability The ease of productivity by the roller rolling method was intuitively evaluated by an operator. The test results are shown in Table 1 below.

[0027]

[Table 1]

From Table 1, it can be seen that the embodiments are all 1 × of the conventional example.
It can be seen that the belt cord breakage resistance is improved and the steering stability and ride comfort are also improved as compared with the steel cord having the three structures. In addition, it can be seen that Comparative Examples 1 and 2 in which the breaking elongation of the metal wire was 1.8 and 3.2% were inferior in the belt cord breaking resistance as compared with the examples. In Examples 2 and 5, although the wire drawing workability was somewhat inferior, the performance as a tire was improved.

[0029]

According to the present invention, there is provided a belt reinforcing material which is a problem of the prior art, in which the belt cord is easily broken at the time of repeated sudden turning without impairing steering stability and riding comfort. Breaking can be suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view illustrating bending rigidity of a tire belt.

FIG. 2A is a cross-sectional view illustrating a rubber material reinforcing material (single metal wire) as an example of the present invention. (B) is sectional drawing which shows the reinforcing material (metal single wire) for another example rubber articles of this invention.

FIG. 3 is a cross-sectional view in the width direction of the pneumatic radial tire.

FIG. 4 is a sectional view of a conventional steel cord.

[Explanation of symbols]

 1, 2 single metal wires 3 belt 4 bead core 5 carcass 6 tread a width b thickness

Claims (4)

[Claims] 1. A reinforcing material for a rubber article, comprising a single metal wire having a substantially rectangular cross section and a breaking elongation of 3.6% or more. 2. A pneumatic tire comprising a belt and a tread radially outside a crown portion of a carcass extending in a toroidal shape between a pair of left and right bead portions, wherein the belt has a substantially rectangular cross section and has a breaking elongation. A pneumatic tire comprising a plurality of 3.6% or more single metal wires arranged in parallel in the tire belt width direction. 3. The pneumatic pneumatic pump according to claim 1, wherein a relationship between a width (major axis) a and a thickness (minor axis) b of a cross section of the single metal wire satisfies a relationship represented by the following equation: a ≧ 2b. tire. 4. The width (major axis) a is 0.5 to 10.0 m.
m, and the thickness (short diameter) b is 0.05 to 0.40 m
The pneumatic tire according to claim 3, which is within a range of m.