JPH1044259A - Composite material of rubber and steel stiffener used for belt part of tire, and pneumatic radial tire using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite material of rubber and steel stiffener adapted to realize a pneumatic radial tire in which durable performance, low fuel cost performance and steering stability performance of the tire are compatible in good balance and the pneumatic radial tire using it for its belt part. SOLUTION: The composite material of rubber and steel stiffener is obtained by cross-laminating two unidirectional stiffeners in which rubber is reinforced by the steel stiffeners at an angle of 15 to 30 degrees, and obtaining main member of hoop clamping an pneumatic radial tire. The unidirectional stiffener is obtained by disposing bundles obtained by bringing at least two or more of steel filaments or steel cords obtained by intertwining the filaments into contact with each other substantially on the same plane and disposing them in parallel in an arraying direction, in parallel at a gap interval (s) of 0.2 to 1.25mm and covering it with coating rubber. When the material is observed so as to pass it in its thickness direction, population (W(%)) of the steel stiffeners to the entire area is set to a range of -50/3.s+305/3<=W<100.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite of rubber and a steel reinforcing material used for a belt intersecting layer of a pneumatic radial tire, and a pneumatic radial tire.

[0002]

2. Description of the Related Art The belt layer of a pneumatic radial tire is
It is an important member that functions as a member for maintaining the shape of a radial tire and as a strength member, and determines various tire performances such as durability performance, steering stability performance, rolling resistance performance, and riding comfort.It is a belt for conventional pneumatic radial tires. The layers are formed by arranging steel cords in parallel, coating them with a coating rubber, and laminating two layers at an intersection angle of 15 to 30 degrees with respect to the equator line of the tire (hereinafter referred to as a cross layer). ) Are used as main members.

[0003] The space between the steel cords of the interlaced layer and the occupation ratio of the steel cord to the whole area when the belt intersecting layer is seen through the thickness direction are conventionally known. In the pneumatic radial tires, there is a relationship that is approximately inversely proportional, where the occupancy is high if the gap is small, and the occupancy is low if the gap is wide. , As shown by the symbol △ in the graph of FIG.

[0004] However, the steel disclosed in Japanese Patent Application Laid-Open Nos. 6-17387 and 7-82679 has been disclosed.
It discloses a code in which a plurality of cord filaments are arranged in parallel and wrapped by a filament having a circular or flat cross section. JP-A-5-5290 discloses a method in which steel filaments are aligned and used as a unit for a belt ply of a radial tire for a passenger car.

[0005]

In recent years, high performance pneumatic radial tires have demanded high performance tires having excellent performance such as durability, abrasion resistance, steering stability and rolling resistance, as automobiles have become more sophisticated. It is rare. On the other hand, fuel economy and weight reduction are important due to problems such as resource saving and pollution.

Here, it has been found that it is important for the steering stability, rolling resistance performance and wear resistance performance of the tire to increase the tensile rigidity of the belt intersecting layer and to improve the shape maintaining function. The inventors of the present invention have conducted intensive studies, and as a result, in order to increase the tensile rigidity of the belt intersecting layer, the steel cord is required to have a larger area than the entire area when the belt intersecting layer is seen through in the thickness direction. We found that we needed to increase the occupancy. However, if the amount of steel cord is increased in order to increase the occupancy, the weight of the tire increases, and the fuel efficiency worsens, and the gap between the steel cords and the occupancy are approximately inversely proportional. Therefore, there is a problem that the gap becomes narrow, the separation propagates quickly at the belt edge, and the durability is deteriorated.

Therefore, it is conceivable to increase the Young's modulus of the steel cord to increase the tensile rigidity of the belt intersecting layer. However, recent steel cords have a sufficiently long pitch to improve productivity. Due to the twist, the Young's modulus could not be so large as to have an effect on tire performance.
Further, it is known that the durability is deteriorated by increasing the pitch, and that the workability at the time of calendar molding is deteriorated.In addition, in the case of the open twist cord, if the pitch is increased, It was expected that rubber permeability would deteriorate and tire durability would be impaired.

The present invention relates to a composite of rubber and a steel reinforcing material suitable for realizing a pneumatic radial tire having a good balance between durability, fuel economy and steering stability of a tire. An object is to provide a pneumatic radial tire used for a belt portion.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and the first aspect of the present invention has been made.
Is a two-way reinforcing material reinforced with rubber with a steel reinforcing material. The longitudinal axis of the steel reinforcing material is substantially symmetrical with respect to the tire equator and intersects at an angle of 15 to 30 degrees. A composite of rubber and a steel reinforcing material which is laminated and is a main member for fastening a pneumatic radial tire, wherein the unidirectional reinforcing material is a steel filament or a steel coil obtained by twisting the filament. A bundle in which at least two or more of them are arranged substantially in parallel on the same plane in parallel with the arrangement direction,
0.2 mm to 1.25 mm, preferably 0.5 mm to
It is arranged in parallel with a gap interval (s) of 1.0 mm and covered with a coating rubber, and when the composite is viewed so as to penetrate in the thickness direction, the steel with respect to the entire area is used. The occupation ratio (W (%)) of the reinforcing material is set to -50 / 3 ·
It is a composite of rubber and steel reinforcing material in the range of s + 305/3 ≦ W <100.

A second aspect of the present invention is a pneumatic radial tire using the composite, comprising: a pair of beats;
A pneumatic radial tire comprising a carcass comprising a radially arranged cord ply extending in a toroidal shape between the beads and a belt layer for holding down a crown portion of the carcass according to the first aspect of the present invention. Wherein the composite of rubber and steel reinforcing material is used as an essential layer of the belt portion.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The object of the present invention is to improve the performance of a pneumatic radial tire such as durability, abrasion resistance, steering stability and rolling resistance. The composite of the first rubber and the steel reinforcing material has a large tensile rigidity because the occupation ratio of the steel reinforcing material with respect to the entire area is defined as described above when viewed through the thickness direction. As a result, steering stability performance, rolling resistance performance, and wear resistance performance are improved.

[0012] The reason is that, when the content is in the above range, the occupation ratio of the steel reinforcing material becomes higher than before, the shear stress between the layers increases, and the tensile rigidity increases. Here, the gap interval of the laminated steel reinforcing members, that is, the so-called interlayer gauge, is in the range conventionally used, and is 0.2 to 1.
Within a range of 5 mm, preferably 0.4 to 1.0 mm.

However, in the prior art, the occupation rate could not be increased without increasing the amount of steel reinforcing material, so that the code gap was narrowed, and the propagation of separation at the belt edge was accelerated, resulting in durability. Had worsened. or,
It is anticipated that the weight will increase and fuel economy will deteriorate.
Therefore, a bundle in which at least two or more steel filaments or steel cords obtained by twisting them are arranged closely and in parallel on a substantially same plane is placed at a gap interval (s) of 0.2 mm or more. This problem is solved by arranging the gaps in parallel with each other.
By setting the thickness to 5 mm or more, the durability can be further improved. That is, the problem of belt edge separation was solved by setting the gap interval (s) between the bundles to 0.2 mm or more, preferably 0.5 mm or more.
Is increased, the penetration resistance is deteriorated, the shear stress between the reinforcing members is reduced, and the tensile rigidity is not increased. Therefore, the gap interval (s) is set to 1.25 mm, preferably 1.0 mm or less. This is a solution to this problem.

[0014] Regarding the above points, the steel filaments disclosed in the above-mentioned Japanese Patent Application Laid-Open Nos. Hei 6-17387 and Hei 7-82679 are arranged in parallel, and the filaments having a circular or flat cross section are used. The wrapped code only discloses the structure of the reinforcing material, but does not disclose how to use it to increase the tensile stiffness of the belt.
Align the steel filaments as one unit,
It is used for a belt ply of a radial tire for a passenger car. Although the structure of one unit is also disclosed,
Nothing is disclosed about how to use the belt to increase the tensile rigidity.

[0015]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples. A pneumatic radial tire in which a composite of rubber and steel cord reinforcing material shown in Table 1 was applied to a belt intersecting layer was prepared, and the steering stability performance, rolling resistance performance, belt edge separation performance, and durability were improved. The wear performance was evaluated.
Further, the belt intersecting layer of the crown center portion was cut out from the tires shown in Table 1 at a width of 50 mm and a length of 400 mm.
Through the line, the occupancy of the steel reinforcement was confirmed. or,
The tensile stiffness of this sample was evaluated. Table 2 shows the results of these evaluations.

FIG. 1 is a schematic view of the arrangement of the steel cord reinforcing material of the composite of Example 1, and FIG. 2 is a schematic view of the arrangement of the steel cord reinforcing material of the composite of Comparative Example 1. In the drawing, 1 is a steel filament, 2 is a steel cord, 3 is a rubber, and s is a gap between steel filaments (steel code).

[0017]

[Table 1]

(Tensile stiffness) The tensile tester catches the sample in the direction of the equatorial line of the tire in the direction of the tensile axis.
The sample was pulled at a speed of m / min, and the displacement was measured at a center distance of 50 mm between the upper and lower chucks to determine and evaluate the tensile rigidity.

(Steering stability performance) A cornering force which affects the steering stability performance of the vehicle was measured. The cornering force was measured by applying a predetermined load after filling the internal pressure after mounting on the specified rim, and using a flat belt type cornering characteristic tester, at a speed of 50 km / h and a slip angle of ±
The cornering force at 2 ° was measured, and the measured values were averaged and evaluated.

(Rolling resistance performance) A test tire adjusted to a predetermined internal pressure was placed on a drum having an outer diameter of 1708 mm,
Preliminary running at 0 km / h for 30 minutes, readjust the internal pressure,
After increasing the number of revolutions of the drum to 200 km / h, the drum was coasted, and the time required for the number of revolutions of the drum to decrease from 185 km / h to 20 km / h was measured, and this was taken as a measure of rolling resistance.

(Belt Edge Separation Resistance) Outer Diameter 1
A test tire adjusted to a predetermined internal pressure was installed on a 708 mm drum tester, and a slip angle of 3.5 ° was intermittently applied. After 12 hours, the tire was dissected to compare the length of a crack formed on a belt edge.

(Abrasion resistance performance) A tire was mounted on an actual vehicle and a field test was carried out. After running around near complete wear, the running distance per 1 mm of wear was calculated.

[0023]

[Table 2]

(Examples 1, 2 and Comparative Examples 1 to 5) Comparative Example 1
5 are compared with Examples 1 and 2, and are expressed as indices with the evaluation result of Comparative Example 1 being 100, and the larger the value, the better the performance. (Example 3 and Comparative Examples 6 to 10) Comparative Examples 6 to 10 are for comparison with Example 3, and the evaluation results of Comparative Example 6 were 100
The larger the value, the better the performance.

As can be seen from the results in Table 2, Examples 1 to 3 were used.
Shows good results in all of the steering stability performance, rolling resistance performance, belt edge separation performance and abrasion resistance performance with respect to each of the comparative examples.

FIG. 3 is a graph of Example 1 to Comparative Example 1 to 10 in which the horizontal axis represents the gap interval (s) between the steel cords of the intersecting layer, and the vertical axis represents the occupancy of the steel reinforcing material with respect to the entire area. It is the figure which plotted this as rate (W). As shown in the above results, the results of Examples 1 to 3 are all superior to those of Comparative Examples, and W
As shown by the oblique line a, the relationship between
05/3 ≦ W <100, and the hatched line b indicates a particularly preferred range.

[0027]

According to the above results, the rubber of the present invention and the stainless steel
It has been found that the use of the composite of the reinforcing material for the belt intersecting layer of the pneumatic radial tire enables the performance of the tire to be compatible with higher dimensions.

[Brief description of the drawings]

FIG. 1 is a schematic view of the arrangement of steel code reinforcements of the composite of Example 1.

FIG. 2 is a schematic view of the arrangement of steel code reinforcements of the composite of Comparative Example 1.

FIG. 3 is a graph of each embodiment and comparative example, in which the horizontal axis represents the gap interval (s) between the steel cords of the intersecting layer, and the vertical axis represents the occupation ratio (W) of the steel reinforcing material with respect to the entire area. FIG.

[Explanation of symbols]

s ‥‥ Spacing of steel code (steel filament), 1 ‥‥ steel filament, 2 ‥‥ steel code, 3 ‥‥ rubber.

Claims (3)

[Claims] 1. A unidirectional reinforcing material reinforced with rubber by a steel reinforcing material, wherein the longitudinal direction of the steel reinforcing material is substantially symmetrical with respect to the tire equator line and is 15 to 30 degrees. A composite of rubber and a steel reinforcing material that is cross-laminated at an angle and is a main member for fastening a pneumatic radial tire, wherein the one-way reinforcing material is a steel filament or a steel twisted with the steel filament. A bundle in which at least two or more of the codes are arranged substantially in parallel on the same plane and in parallel in the arrangement direction, and are arranged in parallel with a gap (s) of 0.2 mm to 1.25 mm; Occupying ratio of the steel reinforcing material to the whole area (W
(%)) Is calculated as −50 / 3 · s + 305/3 ≦ W <10
0. A composite of rubber and steel reinforcing material, characterized in that the range is 0. 2. The gap interval (s) is 0.5 mm to 1.0 m.
2. The composite of rubber and steel reinforcing material according to claim 1, wherein m is m. 3. A carcass comprising a pair of beats, a radially arranged cord ply extending in a toroidal shape between the beads, and a belt layer for clamping a crown portion of the carcass. 2. A pneumatic radial tire according to claim 1, wherein the composite of rubber and steel reinforcing material according to claim 1 is used as an essential layer of a belt portion.