JPH0669763B2 - Radial tire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is a so-called low noise system in which the noise level is significantly reduced without impairing various tire performances such as exercise performance, vibration riding comfort performance, and wet performance. It relates to radial tires.

(Prior Art) In recent years, the noise generated from automobiles has become a major social problem, and even legal regulations have been made regarding automobile noise, and there is an urgent need to reduce the noise level. On the other hand, it is necessary to secure a low noise level in the vehicle from the viewpoint of improving the habitability of the vehicle, and the demand for low noise is indispensable.

Conventionally, regarding noises related to radial tires, it has been said that improvement of the tread pattern or non-uniformity of the pattern pitch is effective for noise reduction. However, such changes in the tread pattern have a great effect on the tire's dynamic performance, particularly on the braking performance and dynamic performance on wet roads, not only significantly restricting the degree of freedom in designing the tire, but sometimes reducing noise. In order to obtain tires, it was often necessary to sacrifice athletic performance.

Therefore, it has been desired to establish a technology capable of reducing noise without changing the tread pattern, but in the past, it has been impossible to find an effective means. For example, in a normal two-piece detachable belt structure, a fold structure (hereinafter referred to as “aramid fold structure”) composed of a combination of a steel cord belt and a folded aramid fiber cord belt (see FIG. 1) has a certain low level. It is possible to make noise, and the tire having such an aramid fold structure is highly evaluated as a tire with good habitability and low noise in the market, but the noise improvement level is 0.2 to 0.3 decibel at most, It was desired to secure a low noise level.

(Problems to be Solved by the Invention) The present inventors have conducted various basic studies for the purpose of obtaining low-noise tires. However, if the pattern is changed as described above, the braking performance on a wet road surface deteriorates. Since there is an antinomy phenomenon like that, it is necessary to take a completely different approach from the conventional technology.

Therefore, the inventors of the present invention also tried to study various tire design factors, but the noise level was reduced by about 1 decibel at most, and so-called total tire performance other than noise, such as exercise performance, vibration riding comfort performance, and wet performance, was obtained. It seemed difficult to obtain tires with satisfactory performance. For this reason, it was necessary to establish a technology for obtaining low-noise tires while maintaining the same level of exercise performance, vibration riding comfort performance, and wet performance as conventional ones.

Therefore, an object of the present invention is to provide a radial tire with further reduced noise without deteriorating the above-mentioned exercise performance, vibration riding comfort performance, and wet performance.

(Means for Solving Problems) The inventors of the present invention have focused their attention on the fact that the conventional aramid fold structure tire has an improved noise level, although it is about 0.3 decibels, as described above. After a study, a high-elasticity and high-strength vinylon cord belt with unprecedented high-strength and high-modulus characteristics was used in combination with a steel cord belt, resulting in a two-piece steel belt structure. The inventors have found that it is possible to reduce the noise by about 3 decibels as compared with the conventional tires that the conventional tire has, and it is possible to reduce the noise by about 2.5 decibels as compared with the tire having the aramid fold structure, and have completed the present invention.

That is, the present invention is a radial tire having a belt reinforcing layer composed of a first belt arranged on the carcass side and a second belt arranged on the tread side, wherein the first belt is a belt using a steel cord. , The second belt has an elongation of 2 under the stress of 4.5 g / d in the raw yarn.
% Or less, the strength is 15.0 g / d or more, and the elongation of the twisted cord tire under the stress of 2.25 g / d is 3
% Or less and the strength is 9.0 g / d or more, a belt using a high elastic modulus and high strength vinylon cord, and the second belt is a fold belt structure in which both widthwise end portions of the tire are folded back to the tread side. Is characterized in that.

Further, in a radial tire having a belt reinforcing layer including a first belt arranged on the carcass side, a third belt arranged on the tread side, and a second belt arranged between the first belt and the third belt, , The first belt is a belt using a steel cord, the second belt and the third belt
The belt has an elongation of 2 in the yarn yarn under 4.5g / d stress.
% Or less, the strength is 15.0 g / d or more, and the elongation of the twisted cord tire under the stress of 2.25 g / d is 3
% Or less and a strength of 9.0 g / d or more, a belt using a high-elasticity, high-strength vinylon cord, and the second belt has both widthwise end portions of the tire folded back to the tread side of the third belt. It has a fold belt structure.

The belt reinforcing layer of the radial tire of the present invention is essential to have a structure in which a belt layer of a steel cord and a belt layer of an organic fiber cord are combined in order to achieve low noise, and particularly, the organic fiber cord is In order to achieve sufficient noise reduction without impairing various tire performances, it is indispensable that the elongation and strength are the high elastic modulus and high strength vinylon defined as described above. That is, like the conventional vinylon yarn, the elongation of the yarn at 4.5 g / d stress is 3.3%,
When the strength was about 11 g / d, the tensile rigidity in the tire circumferential direction was not sufficiently high when the normal twist was applied to this, and there was a problem in tire performance such as steering stability of the tire. Therefore, the belt cord should be used as a yarn to obtain sufficient maneuverability.
Elongation under a stress of 4.5 g / d is required to be 2% or less, and the higher the strength when used as a belt cord, the safer it is. Considering the weak heat deterioration of vinylon. The yarn strength is required to be 15.0 g / d or more. In addition, if such a high-modulus and high-strength vinylon yarn has an elongation of 3% or less under 2.25 g / d stress and a strength of 9.0 g / d or more in a cord after tire vulcanization, it is sufficiently low. It is possible to achieve noise reduction.

Further, if the elongation exceeds 3%, it is inconvenient because the maneuverability is deteriorated, and the strength is set to 9.0 g / d or more from the viewpoint of safety.

If the cord is made thick in order to satisfy these points, the gauge thickness and weight are increased, which adversely affects heat generation and rolling resistance, which is inconvenient.

As a result, as a raw yarn, the elongation under stress of 4.5 g / d is 2
%, In other words, the elastic modulus must be a certain level or more, and the strength must be 15.0 g / d or more. That is, unless the elongation as the yarn of the raw yarn is not more than the above value, the elongation under the stress of 2.25 g / d stress does not become 3% or less when the cord is used with the number of twists which is usually used, and If the strength of the yarn is also not less than 15.0 g / d, the cord strength at the time of tire production will be lower than that of the original yarn due to twisting or cord treatment, and it will be impossible to secure a cord of 9.0 g / d or more.

Further, by using the two-layer structure or the three-layer structure according to the present invention as the belt reinforcing layer, the belt rigidity is not impaired, the maneuverability can be improved, and the noise can be reduced.

Furthermore, by adopting the three-layer structure of the present invention as the belt reinforcing layer, it is possible to further improve maneuverability and noise reduction.

In addition, the folded structure belt has a cord arrangement angle that is opposite to the unfolded portion and the cords are connected, so the movement of the belt is restricted and the rigidity of the belt reinforcing layer itself is increased. It is thought that this will lead to increased maneuverability.

Vinylon with high elastic modulus and high strength is a method of increasing the draw ratio during spinning by using a polymer whose molecular weight is greatly increased compared to that used for conventional vinylon production, and is generally called gel spinning method. Such a method of spinning a polymer having an ultrahigh molecular weight from a dilute solution, or after dry-wet spinning even if the polymer has a not so high molecular weight as disclosed in JP-A-60-126311 and JP-A-60-126312. It can be produced by a method of greatly increasing the draw ratio. Further, heat treatment, post-treatment such as acetalization or formalization of the drawn fiber may be performed to chemically modify the vinylon to improve resistance to wet heat deterioration.

In this way, the yarn of vinylon of high elasticity and high strength produced in this way is subjected to the lower twist and the upper twist to enhance the sizing property of the cord,
Along with this, the fatigue resistance is improved. The twisted cord thus obtained may be weaved using a weft in some cases to form a combed weave, and in some cases, the twisted cord may be soaked in a normal tire cord dip solution such as resorcinol-formaldehyde-latex. After that, it is heat-treated and used as a tire cord.

An aramid fold structure has been conventionally known as such a combined belt structure of an organic fiber cord and a steel cord, but it is difficult to obtain the low noise radial tire which is the object of the present invention with such an aramid fold structure. The elastic modulus of the organic fiber cord is considered as the reason for this.
The tire noise is mainly pattern noise, and it is considered that the pattern noise is a sound generated when the air in the pattern recess is compressed or released when the tire tread is stepped on or off the road surface. That is, in order to reduce the pattern noise, it is important to reduce the increase / decrease in the air pressure in the pattern concave portion of the tread surface.

The air pressure in the pattern depressions on the tread is due to the rigidity of the belt,
In particular, it is considered that the rigidity of the tread and the outermost layer of the belt has a great influence. If the belt has a high rigidity like steel or aramid fiber, the pattern hardly moves when the tire is stepping on or rolling out, and air is trapped in the pattern recesses on the tread surface, resulting in a significant increase in air pressure. However, if the belt rigidity is too small, the pattern will be uniformly crushed, and the compressed air trapped in the pattern concave portion on the tread surface will not escape.

The present inventors have examined the relationship between belt rigidity and pattern noise in detail in view of such a situation. As a result, in the tire of the present invention, the tire of the present invention has a decibel of 2 to 3 decibels as compared with a tire having a belt structure in which two steel cords are separated. We have found that it is possible to reduce noise.

(Example) Next, the present invention will be described with reference to Examples and Comparative Examples.

In the examples and comparative examples, a yarn having the strength and elongation shown in Table 1 measured by the following method was subjected to 30 × 30 T / 10 cm ply twist and ply twist with a structure of 1500 d / 2. , Twisted cord, and normal RFL liquid (resorcin
14 after dipping in formalin / latex adhesive treatment liquid
After a drying process of 0 ° C. × 90 seconds, a heat treatment of 205 ° × 60 seconds was performed. After that, using a belt layer with both sides topped with rubber, a 185 / 70HR13 size radial tire was made using a single ply of 1500d × 2, 40 × 40T / 10cm polyester, and the test shown below. Was carried out.

The belt angle of this test tire was
The temperature is 13 degrees, and the belt-covered rubber is 1.58 × 10 ⁸ at room temperature and 50 Hz.
The dyn / cm ² was used. In addition, the bead portion has a tensile stress M of 40 kg / cm ² at 50% elongation of the bead filler rubber and a carcass ply turn back height of 20 mm. This steel belt tire (185 / 70HR13 GR01 (regno pattern))
Was used as a control. In the following comparative examples and examples, tires having the same structure were used unless otherwise specified.

The high modulus, high strength vinylon fibers shown in Table 1 were manufactured as follows.

First, a 16% DMSO solution of completely saponified PVA with a degree of polymerization of 2600 was used as a spinning stock solution, and the spinning stock solution was discharged into the air from a spinneret with a diameter of 0.10 mmφ, and after running in air of about 5 mm, It was introduced into a methanol coagulation bath to complete the coagulation to obtain an unstretched yarn.

The unstretched yarn was washed with methanol and then dried.
A drawn yarn was prepared by drawing in heated air at 0 to 230 ° C.

(1) Strength and elongation Tensile strength (g / d) and elongation (%) under load of 2.25g / d and 4.5g / d by pulling at 25 ± 2 ℃ at room temperature by autograph according to JIS L1017 And asked. The denier number used was the original yarn denier before twisting. This is to avoid complication of the change in denier due to the change in cord length due to shrinkage during twisting, dipping, and tire vulcanization.

(2) Noise measurement A tire stand test was performed according to JASO (Japan Society of Automotive Engineers) C 606-81. The outline of the test by JASO C 606-81 is shown below.

In such a test, a testing machine equipped with a tire loading device and a drum having a diameter of 3 m, which has a coarse surface having a flat surface and a high friction coefficient as a substitute road surface, was used. Noise was applied so that noise from this tester and the outside would be as small as possible, and the tire load and air pressure were the maximum load specified in JIS D 4202 and the air pressure corresponding to it. Rim is also JIS D
It was a standard rim specified in 4202.

A microphone was installed at a position 1 m away from the tire, and after preliminarily running at 60 km / hour for 30 minutes, the internal pressure and load were readjusted, and the noise level (dB in 30 km / hour to 110 km / hour) was adjusted.
(A)) is measured and the average noise level at all speeds (dB
(A)) was calculated.

(3) Maneuverability A test tire adjusted to an internal pressure of 1.70 kg / cm ² was installed on a drum with an outer diameter of 2500 mm, a load of 395 kg was applied, and then preliminarily run at a speed of 30 km / hour for 30 minutes, with no load. Internal pressure 1.70 kg
/ cm ² was readjusted, a load of 390 kg was applied again, and a slip angle of up to 14 ° was continuously applied on the drum at the same speed. Measure the corner force (CF) at positive and negative angles and use the following formula: The cornering power (CP) was calculated at.

In addition, the index of the CP of each test tire
Dividing by CP, the control tire was set to 100. The larger this index, the better the maneuverability.

Comparative Examples 1 and 4 A belt reinforcing layer is composed of a first belt arranged on the carcass side and a second belt arranged on the tread side, and a separation structure in which cords between these belts are arranged so as to intersect with each other. (Table 2), the arrangement angles of the cords of the first and second belts were both set to 15 ° with respect to the tire circumferential direction.

In Comparative Example 1, as the cord of the belt reinforcing layer, both the first and second belt cords were steel cords, and the structure 1
× 5, filament diameter 0.68 mm and cord strength 65 kg / piece were used. The number of such cords to be driven is 38 / 5cm
The tires currently on the market were used as controls.

In Comparative Example 4, a tire having a belt structure similar to that of Comparative Example 1 was used except that both the cords of the first and second belts had the high elastic modulus and high strength vinylon.

Each of the above tests was carried out on these tires, and the results obtained are shown in Table 2 below.

As can be seen from Table 2, in Comparative Example 4, the belt rigidity is inferior to that of the steel cord belt, and therefore the maneuverability is inferior. Further, since the belt cord is composed only of cords of organic fiber, the bending rigidity is particularly steel. It was inferior to the case of using, and as a result, the movement of the tread increased and the noise level was hardly improved compared to the control.

Comparative Example 2 The same steel cord as in Comparative Example 1 was used as the cord of the first belt, and the aramid fiber cord shown in Table 1 was used as the cord of the second belt. The first and second belts are arranged so that the cords intersect each other at an angle of 13 ° with respect to the tire circumferential direction, and the second belt has a folded structure (Table 2) folded at both ends in the tire width direction. . A tire was manufactured under the same conditions as the control tire except that the aramid cord of the second belt was driven into the fold structure and the number of aramid cords was set to 40/5 cm. The above tests were carried out on this tire, and the results obtained are shown in Table 2 below.

As can be seen from Table 2, the maneuverability is improved due to the fold structure, but the noise level improvement effect was small.

Comparative Example 3 The tire of Comparative Example 3 was the same as the control tire except that the high elastic modulus and high strength vinylon cord was used instead of the steel cord of the second belt of the control tire. When the above-mentioned tests were carried out on this tire, it was found that the noise level was improved by 2.6 dB (A) as compared with the control as shown in Table 2 and the maneuverability was equivalent to that of the control.

Comparative Examples 5, 6, 7 The tires of Comparative Examples 5, 6 and 7 were all those of Example 1 described below except that ordinary vinylon, polyester and nylon cords were used instead of the high elastic modulus and high strength vinylon cords, respectively. Same as tires.

Each of the above tests was carried out on these tires, and the results obtained are shown in Table 2.

As can be seen from Table 2, the noise level is improved in a tire having a fold structure using vinylon or polyester for the cord of the second belt, but the maneuverability is lower than that of the control tire due to the low elastic modulus of the cord. Then dropped. In particular, in the case of a nylon fold structure tire, the elastic modulus of the cord was too low, so that the pattern became easy to move, the noise level was lowered, and the maneuverability was also remarkably lowered.

Example 1 The tire of Example 1 is the same as the tire of Comparative Example 2 except that in the aramid fold structure of Comparative Example 2, the high elastic modulus and high strength vinylon cord was used for the second belt instead of the aramid fiber. And

The above tests were carried out on this tire, and the results obtained are shown in Table 2 below.

According to Table 2, the noise level is 2.8 dB (A) in Example 1.
It was also found that the improvement effect was great. The maneuverability has also been improved compared to the control.

Comparative Examples 8, 9, 10 The tires of Comparative Examples 8, 9, and 10 are, as shown in Table 2, the first, second, and third tires in order from the carcass side to the tread side.
It has a belt reinforcing layer structure composed of a belt, and the second belt has a fold structure in which it is folded back to the tread side of the third belt.

The first belt was made of steel cord, and the second and third belts were usually vinylon, polyester and nylon cords, respectively. Each belt is in the tire circumferential direction
The cords are arranged so as to cross each other at an angle of 13 °, and the number of cords driven into the second and third belts is 40 cords / 5 cm. Other than that, it is the same as the control tire.

For each of these, the same tests were conducted and the results are shown in Table 2. As can be seen from Table 2, the noise levels of Comparative Examples 8 and 9 were improved, but the maneuverability was inferior to that of the control tire due to the insufficient elastic modulus of the cord. In Comparative Example 10, the noise level was not improved, and the maneuverability was significantly reduced.

Example 2 In the tire of Example 2, as shown in Table 2, the first belt was a steel cord belt, the second and third belts were high elastic modulus and high strength vinylon cord belts, and the second belt was It has a fold structure. The other points were the same as in Comparative Examples 8, 9 and 10. When the above-mentioned tests were carried out on this tire, as shown in Table 2, the maneuverability was remarkably improved, and the noise level was also improved, and very good results were obtained.

In the fold structure in each of the comparative examples and the examples, the belt width after folding is 160 mm and the folding width is 43 mm. In other words, about 17% of the total width of the second belt
Are folded back to the tread side on both sides.

(Effects of the Invention) As described above, the two layers or the three layers according to the present invention are used.
In a radial tire having a belt reinforcement layer of a layer, by using a vinylon cord belt having a predetermined high elastic modulus and high strength in combination with a steel cord belt, it is possible to obtain tire performance such as exercise performance, vibration ride comfort performance, and wet performance. The effect that sufficient noise reduction is achieved can be obtained without impairing various performances.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a belt-reinforcing layer, which has a fold structure and is separated into two sheets.

Claims (2)

[Claims] 1. A radial tire having a belt reinforcing layer including a first belt arranged on the carcass side and a second belt arranged on the tread side, wherein the first belt is a belt using a steel cord, and 2 belts have an elongation of 2% or less and a strength of 15.0 g / d or more in a yarn yarn under 4.5 g / d stress, and in a tire of a cord formed by twisting the same under 2.25 g / d stress. A belt using a vinylon cord having an elongation of 3% or less and a strength of 9.0 g / d or more, and the second belt has a fold belt structure in which both widthwise end portions of the tire are folded back to the tread side. Radial tires featuring. 2. A belt reinforcing layer comprising a first belt arranged on the carcass side, a third belt arranged on the tread side, and a second belt arranged between the first belt and the third belt. In the radial tire having, the first belt is a belt using a steel cord, and the second belt and the third belt are 4.5 g in the yarn yarn.
/ d The elongation under stress is 2% or less and the strength is 15.0 g / d or more. 2.25 g /
A belt made of vinylon cord having an elongation under d stress of 3% or less and a strength of 9.0 g / d or more, and the second belt has both widthwise ends of the tire on the tread side of the third belt. A radial tire characterized by having a folded belt structure that is folded back.