JPH07156617A - Radial tire for high speed heavy load - Google Patents

Abstract

PURPOSE:To prevent a bead core from being separated, and thereby enhance the durability of a bead section. CONSTITUTION:This invention is concerned with the high speed heavy loading radial tire provided with a bead core substrate 4 which has a plurality of metal plated element wires wound into a plurality of layers, and with a rubber shielding layer 5 which is disposed over its outer circumferential surface for shielding the bead core substrate, besides the aforesaid tire comprises a bead core 3 provided for a bead section where the thinnest thickness of the rubber shielding layer is 0.3 to 1.8mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-speed heavy-duty radial tire having improved durability of a bead portion.

[0002]

2. Description of the Related Art In recent years, structural durability of tires used under high load and high speed conditions, such as aircraft tires,
A radial structure is being adopted to improve running performance and weight reduction.

However, in such a radial tire for an aircraft, since the bead portion is largely bent and deformed because it is used under a high load condition as described above, the bead is subjected to the impact high speed running at the time of taking off and landing and the braking. A large stress acts on the part, and the internal temperature rises greatly. Due to such deformation and temperature rise, adhesion is lowered between the bead core and the rubber such as carcass topping, bead apex and bead filler topping rubber, and peeling occurs between the bead core substrate and the rubber.

[0004]

In order to improve the adhesion performance between the bead core and the rubber around the bead core, a method of forming the bead core by using a steel element wire plated with metal has been proposed, but none has been proposed. It was not possible to obtain stable adhesive performance simply by applying metal plating intentionally.

As a result of repeated studies to solve the above-mentioned problems, the inventors have conducted a metal coating on a steel wire and, in addition, a rubber coating covering a bead core substrate formed by using the steel wire having the above-mentioned structure. By providing a layer, it is possible to prevent peeling between the bead core and the members such as the carcass, bead apex, bead filler, etc., which are arranged around the bead core, and the bead portion can be applied even if the tire has a high speed and a large load such as an aircraft tire. The inventors have found that the durability of can be improved and completed the present invention.

It is an object of the present invention to provide a high speed heavy duty radial tire having an improved durability of the bead portion.

[0007]

According to the present invention, there is provided a bead core substrate formed by winding a plurality of layers of steel wire having a metal plated surface, and a bead core substrate disposed on the outer peripheral surface of the bead core substrate. A rubber coating layer for covering the rubber and covering the thinnest portion of the rubber coating layer with a rubber thickness of 0.3.
A radial tire for high-speed heavy load, comprising a bead core having a diameter of not less than mm and not more than 1.8 mm provided at a bead portion.

The rubber coating layer has a complex elastic modulus E * of 80 to
It is preferably formed by a rubber composition of 200 kgf / cm ² .

The rubber coating layer is made of rubber polymer 100.
In addition to containing 0.5 to 5.0 parts by weight of cobalt salt with respect to parts by weight, the steel wire has a Cu content of 60 to 75% by weight and a Zn content of 25 to 40% by weight. / Zn plating is 0.3 ~ per 1kg of steel wire
It is more preferable to perform metal plating with a deposition amount of 0.8 g.

[0010]

In the bead core substrate, a plurality of steel element wires each having a metal plated surface are wound in a plurality of layers. This prevents rusting of the steel wire and enhances the durability of the bead core, and also enhances the adhesiveness between the rubber coating layer and the bead base.

The bead core substrate is covered with a rubber coating layer. Therefore, the bead core substrate does not come into direct contact with the carcass and the bead apex, and the rubber coating layer provided for coating can select the rubber composition mainly on the adhesiveness with the bead core substrate, so that the steel strands The bead core formed by the method can surely be fixed at the bead portion.

By providing such a rubber coating layer, a strong adhesion reaction layer is formed on the surface of the bead core, and the adhesion between the bead core substrate and the rubber can be improved.

The thickness of the rubber in the thinnest part of the rubber coating layer is 0.3 mm or more and 1.8 mm or less. If the rubber thickness is less than 0.3 mm, good adhesion cannot be obtained, and if it exceeds 1.8 mm, the rubber thickness of the rubber coating layer becomes excessive and heat generation at the bead portion caused by tire rotation becomes large.

By thus metal-plating the steel element wires and organically bonding and integrating the provision of the rubber coating layer, it is possible to suppress a decrease in adhesive force due to heat generation in the bead portion due to tire rotation. It is possible to prevent the bead core from peeling and improve the durability of the bead portion.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings by taking a case where a radial tire for high speed heavy load is a tire for aircraft as an example.

In FIG. 1, which shows a normal internal pressure state in which the normal rim R is attached and the normal internal pressure is filled, a high speed heavy load radial tire 1 includes a tread portion 12 and sidewall portions extending inward in the tire radial direction from both ends thereof. 13, 13
And the bead portions 2 and 2 located at the inner ends of the sidewall portions 13. In addition, each bead part 2 has a bead core 3
While being reinforced by the carcass 16, a carcass 16 is bridged between the bead cores 3 and 3, and a belt layer 17 is wound around the carcass 16 in the radial direction, and in the present embodiment, the carcass 16 and the belt layer 17 are provided. A cut breaker layer 18 is provided between the cut breaker layer 18 and the cut breaker layer 18.

The carcass 16 extends from the tread portion 12 to both sides and extends to the bead portion 2 through the sidewall portion 13 and the main body portion 16a. From the tread portion 12 to the side wall portion 13 and the bead portion 2 which is arranged outside the inner layer 16A and is formed of a plurality of, for example, four winding plies provided with a folded-back portion 16b that is wound up from the inside to the outside. The outer layer 6B which extends inward in the radial direction of the bead core 3, and in the present embodiment, one or a plurality of, in this example, two lowering plies, which extend outside the folded-back portion 16b of the winding ply in the axial direction of the tire.
And with. The winding ply and the lowering ply have a radial configuration in which carcass cords made of organic fibers such as nylon, rayon, polyester, and aromatic polyamide are arranged at an angle of 75 to 90 degrees with respect to the tire equator C, and in this example, 85 degrees. None, each ply is oriented differently as the carcass cords intersect each other between the plies.

A bead apex 14 made of hard rubber extending in a tapered shape is provided on the outer side of the bead core 2 in the radial direction of the tire, and is provided between the main body portion 16a of the winding ply 16A and the folded portion 16b and the lowering ply 16B. It alleviates the working shear force.

The belt layer 17 comprises a plurality of belt plies, which are stacked in this order from the carcass 16 side toward the tread surface side in this example, and each belt ply has a ply width in the tire axial direction. It is set larger than the ply width of the belt plies that are adjacent on the outside. In each belt ply, the belt cords made of organic or inorganic fibers such as nylon, rayon, polyester, aromatic polyamide and carbon are arranged substantially parallel to the tire equator C, in this example the tire equator C. is doing.

The cut breaker layer 18 is a tire equator C made of a breaker cord made of an organic or inorganic fiber such as nylon, rayon, polyester, aromatic polyamide or carbon.
On the other hand, it is formed by one or a plurality of breaker plies arranged at an angle of 25 degrees or less, in this example, 19 degrees, in this example, two breaker plies. Each breaker ply is oriented so that its breaker cords cross each other between the plies.

As shown in FIG. 2, the bead core 3 comprises a bead core base 4 and a rubber coating layer 5 which is arranged on the outer peripheral surface of the bead core base 4 and covers the bead core base 4.

The bead base body 4 is formed by winding a steel base wire 6 into a plurality of layers, as shown in FIG.

In this embodiment, a plurality of surrounding steel element wires 6B are arranged in four layers around the steel element wire 6A of the core portion which is arranged in the center, and the steel wire element 6A has a substantially circular cross section. The bead core substrate 4 is formed.

In the present embodiment, the core steel wire 6A is formed with a wire diameter of 6 mm, and the surrounding steel wire 6B is formed with a wire diameter of 2.2 mm.

The surrounding steel wire 6B is a hard wire rod,
For example, a piano wire rod S specified in JIS G 3502
WRS77A or 82A, JIS G 3506
The hard steel wire rod specified in can be adopted. The diameter of the steel wire is preferably in the range of 0.8 to 3.0 mm.
Further, the steel wire 6A of the core portion may be made of a hard or soft steel wire, and its diameter is preferably larger than that of the surrounding wire 6B.

The steel wire 6 is subjected to a metal plating treatment prior to the formation of the bead core substrate 4. In this example, the metal plating has a Cu content of 60 to 75% by weight,
It is a Cu / Zn binary plating having a Zn content of 25 to 40%, and is applied at an amount of 0.3 to 0.8 g per kg of steel wire.

The steel wire 6 has such a plating composition,
By applying metal plating according to the amount of plating, the adhesive force between the rubber coating layer 5 and the rubber coating layer 5 can be increased.

When the amount of plating adhered is less than 0.3 g per kg of steel wire, the activation of the adhesive reaction due to plating is reduced and the adhesion speed is slowed down, and the vulcanization speed of the rubber coating layer 5 matching this is decreased. When trying to obtain the rubber, angucure of the rubber is likely to occur during vulcanization. Also 0.
If it exceeds 8 g, the activation of the adhesion reaction due to plating increases and the adhesion speed increases, and there is a risk of rubber burning when an attempt is made to obtain a vulcanization speed of a rubber matching this.

There is no particular limitation on the Cu / Zn plating, and commonly used methods such as a substitution method and a diffusion method can be adopted, and there is no particular limitation on the method of depositing the plating. It suffices that the plating is as uniform as the plating applied to the wire.

Generally, the compression shearing force and heat generated by the deformation of the bead portion caused by the rotation of the tire reduce the adhesive force between the bead core substrate 4 and the rubber around the bead core substrate 4 and cause peeling. Due to this peeling, the carcass ply of the bead core, the bead apex of the bead core, and the looseness of the entire bead portion between the bead core and the peripheral members surrounding the bead core such as the bead filler will occur, leading to a decrease in the durability of the bead portion 2. .

As in this embodiment, by providing the rubber coating layer 5 on the outside of the bead core substrate 4 formed of the steel strand 6, the adhesive force between the bead substrate 4 and the members arranged around the bead substrate 4 is increased. Further, the propagation of the compressive shearing force generated by the rotation of the tire to the bead core substrate can be alleviated, and the decrease in the adhesive force can be suppressed.

The rubber coating layer 5 has a rubber thickness t at its thinnest portion of 0.3 mm or more and 1.8 mm or less. If the rubber thickness t is less than 0.3 mm, good results cannot be obtained between the rubber forming the rubber coating layer 5 and the bead core substrate 4. This is because the rubber thickness t is less than 0.3 mm and the sulfur content that enhances the adhesive force is insufficient. Moreover, the impact force due to the rotation of the tire is propagated to the bead core base body 4, and the adhesive force between the bead base body 4 and the members arranged around it is lowered. On the other hand, when the rubber thickness t exceeds 1.8 mm, the heat of the bead core generated by the tire rotation becomes large, the deterioration of the rubber coating layer 5 is accelerated, and the durability is deteriorated. In order to improve durability, it is more preferable to set the rubber thickness t in the range of 0.5 to 1.5 mm.

Further, in this embodiment, the rubber coating layer 5 is formed of a rubber composition having a complex elastic modulus E * of the rubber E * 80 to 200 kgf / cm ² . The complex elastic modulus E * is 8
If it is less than 0 kgf / cm ² , the rigidity is insufficient, and the movement of the bead core base body 4 is remarkably generated by the rotation of the tire, while the heat generation is large.
If it exceeds 00 kgf / cm ² , the impact caused by the tire rotation is propagated to the bead core substrate, so that the bead substrate 4 and the rubber coating layer 5 are easily separated.

The rubber coating layer 5 is made of the rubber polymer 10
To 0 parts by weight, 2 to 10 parts by weight of sulfur is blended in order to obtain good adhesion between the rubber and the metal plating, and 0.5 to 5.0 parts by weight to obtain more stable adhesion. Contains cobalt salt. As a typical example of rubber polymer,
Natural rubber, a blend of natural rubber and isobrene rubber,
There are blends of natural rubber, isobrene rubber, and liquid isobrene rubber.

If the content of the cobalt salt is less than 0.5 parts by weight, the effect of stabilizing the adhesive strength is not obtained, and if it exceeds 5.0 parts by weight, the change of the screws during raw rubber is large and the manufacturing process is hindered.

Another example of the bead core 3 is shown in FIGS. In FIG. 3, a long steel element wire 6 coated with metal is spirally wound into a plurality of layers to form a bead core base 4 having a rectangular cross section, and the bead core base 4 is covered with a rubber coating layer 5. .

FIG. 4 shows another example in which a steel wire 6 is wound to form a bead core substrate having a hexagonal cross section, and in FIG. 5, a core obtained by winding the steel wire 6 in a hexagonal shape is shown. The bead core substrate 4 is formed by winding an outer layer 4D having an annular shape of the steel element wire 6 on the outer side of the portion 4C. In this way, the bead core substrate 4 can be formed in various sectional shapes.

[0038]

SPECIFIC EXAMPLE A tire having a tire size of 46 × 17R20 and having the configuration shown in FIGS. 1 and 2 was prototyped according to the specifications shown in Table 1 (Examples 1 to 5), and its performance was tested. . A tire having a conventional structure without a rubber coating layer (conventional example 1) and a tire having a structure other than the structure of the present application (comparative example) were also tested to compare their performances.

Table 2 shows the rubber composition in which the content ratio of the cobalt salt was changed (Reference Examples 1 to 5) and the rubber composition.
Tests were also carried out on those having different complex elastic moduli as shown in (Reference Examples 6 to 9) to compare their performances.

The metal plating applied to the steel wire is
In each of the example, the conventional example, the comparative example, and the reference example, Cu is 6
Cu / Zn plating containing 0 to 75% by weight made the amount of adhesion 0.3 to 0.8 g per 1 kg of steel wire.

The test method is as follows. 1) Complex elastic modulus E * viscoelasticity spectrometer VES-F- manufactured by Iwamoto Seisakusho
Type III, temperature 70 ℃, initial strain 10%, dynamic strain ± 1
%, Measured at a frequency of 10 Hz.

2) Adhesion between the rubber coating layer and the bead core substrate A five-step evaluation was performed and the larger the value, the better.

3) Heat generation at the bead portion A test was conducted by a 100% load taxi simulation using a drum tester in accordance with the United States Civil Aviation Bureau standard TSO-C62C, and the temperature of the bead portion was measured at the end of 100 cycles. It is expressed by an index with 3 being 100. The smaller the value, the lower the exothermic temperature.

4) Change in screw of rubber coating layer After each sample was left for 20 days, a Mooney viscosity test according to JIS K-6300 was carried out. If the index was 100 or less, it indicates that the screw was lowered. Table 1 shows the test results
Shown in.

[0045]

[Table 1]

[0046]

[Table 2]

As a result of the test, good results were obtained when the rubber thickness t of the rubber coating layer was 0.3 mm or more, preferably 0.5 mm or more, and when the thickness was 2.0 mm, the heat generation at the bead portion was large. It was confirmed.

Further, as shown in Reference Examples 1 to 5, in the range containing 0.5 to 5.0% by weight of cobalt salt, the change in Mooni bis was insignificant, and in the case containing 7.0% by weight, the bis change was small. It was confirmed to be large.

[0049] Further, the intended complex elastic modulus E of the rubber-coated layer as in Reference Example 6-9 * is 80~200kgf / cm ² was good without swelling of the bead portion, too soft at 60 kgf / cm ² Also, it was found that 300 kgf / cm ² was too hard and the durability of the bead portion was poor.

[0050]

As described above, the radial tire for high speed heavy load of the present invention has the above-mentioned constitution, thereby suppressing the heat generation of the bead core generated during the rotation of the tire, preventing the bead core from peeling, and improving the durability of the bead portion. Improve sex.

[Brief description of drawings]

FIG. 1 is a right half sectional view of a tire showing an embodiment of the present invention.

FIG. 2 is a sectional view showing the bead core.

FIG. 3 is a cross-sectional view showing another example of a bead core.

FIG. 4 is a sectional view showing another example of a bead core.

FIG. 5 is a cross-sectional view showing another example of a bead core.

[Explanation of reference numerals] 2 bead portion 3 bead core 4 bead core substrate 5 rubber coating layer 6 steel strand t rubber thickness

Claims (3)

[Claims] 1. A bead core base formed by winding a plurality of layers of steel strands whose surfaces are metal-plated, and a rubber coating layer arranged on the outer peripheral surface of the bead core base to cover the bead core base. A high-speed heavy-duty radial tire having a bead core having a bead core having a rubber thickness of 0.3 mm or more and 1.8 mm or less at the thinnest portion of the rubber coating layer. 2. The rubber coating layer has a complex elastic modulus E * of 80.
The radial tire for high-speed heavy loads according to claim 1, which is made of a rubber composition of about 200 kgf / cm ² . 3. The rubber coating layer contains 0.5 to 5.0 parts by weight of a cobalt salt with respect to 100 parts by weight of a rubber polymer, and the steel wire has a Cu content of 60.
~ 75 wt%, Cu with a Zn content of 25-40 wt%
/ Zn plating 0.3-0.8g per kg of steel wire
2. The metal plating is performed according to the adhesion amount of
Alternatively, the high-speed heavy-duty radial tire according to item 2.