JPH08164703A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE: To provide a pneumatic radial tire for a passenger can which can prevent the breakage of a cord in a cord layer, which is apt to occur when the cord in the cord layer is exposed to the outside or when the car makes hasty cornering, and enable a driver realize through his/her visual sensation that the tire is in danger. CONSTITUTION: In an organic-fiber-made cord belt layer 7 situated above an inclined belt layer 6, which is formed by arranging a steel-made reinforcing element at the outer periphery of a crown part 4, a cord in the cord belt layer 7 has a breaking strength of more than 1000kgf per 50mm in width when measured in the normal direction to the cord, while the breaking elongation of the cord is more than 4%. The cord in the belt layer 7 in the circumferential direction has such as object color in the yellow color system as 0.3<x<0.7, 0.3<y<0.7 when denoted by chromaticity coordinates x, y in the XYZ color system of the CIE chromaticity diagram specified by JIS.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single inclined belt layer in which a plurality of steel reinforcing elements are obliquely arranged with respect to the equatorial plane of a tire, and an organic fiber cord is provided on the inclined belt layer. The present invention relates to a pneumatic radial tire having a reinforcing belt composed of at least one circumferential belt layer arranged substantially parallel to the tire equatorial plane, and more particularly to a general-purpose passenger car tire.

[0002]

2. Description of the Related Art Nowadays, there is a growing demand for energy saving, and in automobiles, studies have been made to improve fuel efficiency by reducing weight. Along with this, demands for weight reduction of tires are also increasing year by year. This tendency is particularly remarkable in general-purpose passenger car tires.

A pneumatic radial tire generally has a so-called cross belt in which at least two inclined belt layers are laminated around the crown portion of the carcass so that their steel cords intersect each other. On the other hand, a pneumatic radial having a reinforcing belt including one inclined belt layer and a circumferential belt layer in which the inclined belt layer and organic fiber cords are arranged substantially parallel to the equatorial plane of the tire are provided. The tire is US Pat.
No. 2 specification.

By the way, in the pneumatic radial tire, the cord of the belt may be exposed at the end of use of the tire due to abrasion of the tread rubber during running.

[0005]

In the tire having the simplified belt proposed in the above publication, the circumferential belt layer is located on the outer side in the radial direction, and the cord of the circumferential belt layer is higher than that of the steel cord. Since the cord of the circumferential belt layer substantially bears the circumferential tension generated in the belt due to the internal pressure filling, it is an organic fiber cord with a small breaking strength, so that the cord of the belt is exposed. When the vehicle continues to run, the cord is more likely to break due to the unevenness of the road surface or the frictional force caused by stones, etc., as compared with a general pneumatic radial tire. Once a cord breaks, adjacent cords will break in a chain,
Eventually, it could lead to a tire burst, which was extremely dangerous for the driver. Therefore, when the cord of the belt is exposed, it is necessary for the driver to quickly recognize the limit of use of the tire.

In a general pneumatic radial tire, if the belt cord is exposed and the vehicle continues to run,
Since the belt cord is made of steel, reddish "iron rust" appears on the cord surface due to moisture in the air or on the road surface.
Occurs, and the surface of the cord present in the black rubber portion changes to red, which allows the driver to recognize the limit of use of the tire. In this case, since the cord of the circumferential belt layer located on the outer layer side of the belt is an organic fiber cord, when the cord is exposed and further continued to run, like a general pneumatic radial tire, the cord is The phenomenon that the surface of the tire changed to a color different from the black rubber portion could not occur, and it was difficult for the driver to recognize the use limit of the tire.

In addition, in the case where rapid cornering is repeated, in-plane bending deformation occurs in the belt,
Forcible tensile strain of the cord is generated especially at the end of the circumferential belt layer, so if the limit elongation of the circumferential belt layer is small, cord rupture occurs due to the above-mentioned forced tensile strain of the cord. If the vehicle continues to run in this state, it may lead to a tire burst as described above.

Therefore, an object of the present invention is to make the circumferential strength that tends to occur in a sharp cornering run by optimizing the breaking strength of the circumferential belt layer, the breaking elongation of the cord, and the color of the cord. It is an object of the present invention to provide a pneumatic radial tire, in particular, a general-purpose passenger vehicle tire, which can prevent the cord of the directional belt layer from being broken and can promptly recognize the danger to the driver.

[0009]

In order to achieve the above object, a pneumatic radial tire of the present invention comprises a plurality of steel members on the outer periphery of a crown portion of a carcass that forms a toroidal shape across at least a pair of bead cores. One layer of a slanted belt layer in which the reinforcing elements made of slant are arranged with respect to the equatorial plane of the tire, and at least 1 layer of organic fiber cords arranged on the slanted belt layer and substantially parallel to the equatorial plane of the tire. A tread portion reinforced with a reinforcing belt consisting of a circumferential belt layer and the circumferential belt layer has a breaking strength of 1000 kgf or more per 50 mm width measured in the direction perpendicular to the cord, and the breaking elongation of the cord is 4 % Or more, and the cord of the circumferential belt layer is C defined by JIS.
In the IE chromaticity diagram, chromaticity coordinates x, y in the XYZ color system
, 0.3 <x <0.7, 0.3 <y <0.7, respectively
And has a yellowish object color. Here, the steel reinforcing element specifically means a steel cord or monofilament. Further, it is preferable that the cords of the circumferential belt layer are spirally wound for the reason of ensuring the uniformity of the tire.

In addition, the circumferential vector layer may have two layers at the crown center portion and one layer at the remaining crown portion, or two layers at the crown end portion and one layer at the remaining crown portion. preferable.

The object color is measured by (1) the type of measuring method, (2) the type of color matching function, (3) the type of standard light,
(4) The geometrical conditions of illumination and light reception were set as follows. (1) Type of measurement method Measurement was performed using a spectrophotometer with one optical path. Effective wavelength width is 1
It is 0 nm. (2) Kind of color matching function The color matching function of the XYZ color system was used. (3) Types of standard light Standard light D ₆₅ was used. (4) Geometric condition of illumination and light reception The geometric condition of illumination and light reception was set as condition c. That is, the light was uniformly illuminated from all directions, and the reflected light in the direction of an angle of 8 ° with the normal was received.

[0012]

The general-purpose pneumatic radial tire having the simplified belt has the following advantages as compared with general pneumatic radial tires. It is difficult for the driver to quickly recognize that the cord is exposed. 2. When the vehicle sharply repeats cornering, the cord is likely to break and cause a tire burst. As mentioned above, there is a problem.

Therefore, the inventors of the present invention have conducted studies for solving the problems 1 and 2 described above. As a result, in order to solve the above-mentioned problem 1, the organic fiber cord of the circumferential belt layer is colored in advance with a color different from that of the rubber part and with a yellow system known as a universal color as a color for warning. In addition, in order to solve the above-mentioned problem 2, it is considered that the breaking strength of the circumferential belt layer and the breaking elongation of the cord of the circumferential belt layer should be increased, and the optimization of these is aimed at. I decided.

That is, in the pneumatic radial tire of the present invention, the breaking strength of the circumferential belt layer is 1000 kgf or more per width 50 mm measured in the direction perpendicular to the cord, and the breaking elongation of the cord is 4% or more. This prevents cord breakage in the circumferential belt layer, which tends to occur during sharp cornering travel.

The cord of the circumferential belt layer is JIS
In the CIE chromaticity diagram defined by, the chromaticity coordinates x and y in the XYZ color system are 0.3 <x <0.7,0.
The driver can quickly recognize that the organic fiber cord of the circumferential belt layer is exposed by setting the yellowish object color in the range of 3 <y <0.7.

[0016]

EXAMPLES Specific examples of pneumatic radial tires according to the present invention will now be described with reference to the drawings.
FIG. 1 shows a cross section in the width direction of a typical pneumatic radial tire according to the present invention. In the figure, 1 is a pneumatic radial tire, 2 is a bead core, 3 is a carcass, 4 is a carcass crown portion, and 5 is a tire equator. Surface, 6 is an inclined belt layer,
Reference numeral 7 is a circumferential belt layer, 8 is a reinforcing belt, and 10 is a tread portion.

The pneumatic radial tire 1 has a toroidal carcass 3 that extends between a pair of bead cores 2.
1 × 5 × 0.23 more structure on the outer circumference of the crown portion 4 of
One layer of the inclined belt layer 6 in which steel cords having a driving number of 37/50 mm are inclinedly arranged at an angle of 35 ° with respect to the tire equatorial plane 5, and the cords are located on the inclined belt layer 6. It comprises a tread portion 10 reinforced by a reinforcing belt 8 consisting of one circumferential belt layer 7 which is wound and arranged in a spiral shape substantially parallel to the equatorial plane of the tire. The cord of the circumferential belt layer 7 is preferably a cord of relatively high elasticity such as aramid or rayon in order to obtain cornering power. In this example, a polyamide cord having a structure of 1000d / 2 was used. Further, breaking extension is proportional to the value of the twist coefficient N _t, to adjust the elongation at break by changing the twist coefficient N _t. Table 1 shows the values of the twist coefficient N _t , elongation at break, and breaking strength. , Examples 1 to 6 are those in which the values of breaking elongation and breaking strength are within appropriate ranges, and Conventional Examples 1 to 3 are
At least one of the values of elongation at break and strength at break is outside the proper range. The twisting factor N _t is N _t = T × (0.139 × D _T / 2 × 1 /) where T is the number of twists of the cord (number of times / 10 cm), total denier is D _T , and specific gravity is ρ. ρ) ^1/2 × 10 ^-3 . Further, in Conventional Examples 1 to 3, the cords of the circumferential belt layer were not subjected to coloring treatment, but Examples 1 to 6 were used.
Indicates that the cord of the circumferential belt layer is colored in red, and the chromaticity coordinates x and y are 0.55 and 0.40, respectively.
And

[0018]

[Table 1]

(Test method) The test was carried out by using J
The maximum internal pressure and the maximum load determined by the ATMA standard were used, and the durability drum test with slip angle was performed. The test method was such that, after running for 20 seconds at a slip angle of + 2 ° and then running for 20 seconds at a slip angle of −2 °, the running mode was repeated for 20,000 km to run the end portion of the circumferential belt layer. The remaining strength of the cord was measured. The residual strength is obtained by disassembling a new tire and subjecting the cord taken out to a tensile test, and the force at break at this time is set to 100%. The measured value of the residual strength is 68% or more. It was a level. This passing level is that in the above-mentioned endurance drum test, no rupture occurred even after running 100,000 km without slip angle.

[0020]

[Table 2]

In the conventional examples 1 and 3, the cord of the circumferential belt layer was cut, and in the conventional example 2, only the residual strength of 30% was obtained, whereas in the examples 1 to 6, the passing level was obtained. The remaining strength of was obtained. Also, scraping off the tread rubber,
When the appearance of the tire was checked in the state where the cord of the circumferential belt layer is exposed, in the conventional examples 1 to 3, it cannot be distinguished unless the cord is exposed carefully.
In Examples 1-6, it was immediately found that the cord was exposed.

[0022]

According to the present invention, when the cord of the circumferential belt layer is exposed, it is possible to prompt the user to recognize the danger of tire burst, and when repeated rapid cornering, It has become possible to provide a general-purpose pneumatic radial tire that prevents cord breakage in the circumferential belt layer and prevents tire bursts from occurring.

[Brief description of drawings]

FIG. 1 is a cross-sectional view in the width direction of a typical pneumatic radial tire according to the present invention.

[Explanation of symbols]

 1 Pneumatic radial tire 2 Bead core 3 Carcass 4 Carcass crown part 5 Tire equatorial plane 6 Inclined belt layer 7 Circumferential belt layer 8 Reinforcement belt 10 Tread part

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location B60C 23/00 Z

Claims (2)

[Claims] 1. A single inclined belt layer formed by arranging a plurality of steel reinforcing elements in an inclined arrangement with respect to an equatorial plane of a tire on the outer circumference of a toroidal carcass crown portion that straddles at least a pair of bead cores. And air having a tread portion reinforced by a reinforcing belt, which is located on the inclined belt layer and has at least one circumferential belt layer in which organic fiber cords are arranged substantially parallel to the tire equatorial plane. In radial tires with inner circumference, the circumferential belt layer has a width of 5 in the direction perpendicular to the cord.
It has a breaking strength of 1000 kgf or more per 0 mm, and the breaking elongation of the cord is 4% or more. The cord of the circumferential belt layer is CIE specified by JIS.
In the chromaticity diagram, the chromaticity coordinates x and y in the XYZ color system are
A pneumatic radial tire characterized by having a range of 0.3 <x <0.7 and 0.3 <y <0.7, respectively, and having a yellowish object color. 2. The pneumatic radial tire according to claim 1, wherein the cord of the circumferential belt layer is wound in a spiral shape.