JPH06305304A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve the durability in high speed without increasing noises in a passage of a pneumatic tire by forming a band layer disposed outside a belt layer of a band ply having band cores finally twisted with both strands of nylon and polyester. CONSTITUTION:A pneumatic tire is provided with at least a band layer disposed outside a belt layer. Then, the band layer is formed of two inner and outer layers, and respective band plies forming two inner and outer layers are formed of band cords 11 arranged in parallel, i.e., the band cord 11 as a composite cord is formed of nylon filaments 12 and polyester filaments 13. Also, a plurality of nylon filaments 12 are bundled up and undercoated to form a nylon strand 14. Further, a plurality of the polyester filaments 13 are bundled up and undercoated to form a polyester strand 15. The nylon strand 14 and polyester strand 15 are finally twisted to form the band cord 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire capable of improving high-speed durability and suppressing passing noise.

[0002]

2. Description of the Related Art With the recent development of highway networks, there is an increasing demand for higher speeds regardless of the size of large vehicles such as passenger cars and trucks. Even in a tire, a so-called lifting phenomenon occurs in which the tread portion bulges outward in the radial direction due to a centrifugal force generated in the tread portion due to the rotation of the tire as the speed increases.

Further, the deformation of the tire due to the lifting not only promotes the vibration of the tire, but also raises the belt layer, causing separation between the belt layer and its surrounding rubber and carcass. Particularly when a steel cord is used for the belt layer, there is a problem that the peeling is further promoted due to insufficient adhesion between the cord and the topping rubber, and high-speed durability is impaired.

In order to suppress the lifting, there is a tire in which a band layer made of a ply using a nylon cord is wound on the outside of the belt layer, but such a nylon cord winding increases centrifugal force at high speed running. Therefore, it was insufficient to suppress lifting.

[0005]

SUMMARY OF THE INVENTION In order to solve some of the above problems, JP-A-54-45007 and JP-A-61 are used.
-71204, Japanese Patent Application Laid-Open No. 1-247204, etc., an aromatic polyamide fiber having high elasticity;
It has been proposed to use a composite cord formed by twisting low-elasticity nylon fibers in the band layer.

However, when the composite cord is formed by using the aromatic polyamide fiber, the elasticity is increased and the above-mentioned lifting can be suppressed, but a high noise is generated during running,
Further, the increase in cost has hindered its widespread use.

The inventors of the present invention have conducted earnest research to create a composite cord for a tire that can be economically provided while retaining the effect of suppressing lifting, and as a result, it has a higher elasticity than nylon fiber and is an aromatic polyamide fiber. It was found that the above-mentioned problems can be solved by paying attention to a polyester fiber which is cheaper than the above, and forming a composite cord of the polyester fiber and the nylon fiber.

The present invention can effectively suppress lifting during high-speed traveling without increasing passing noise.
The purpose of the present invention is to provide a pneumatic tire that has high-speed durability and can be economically produced.

[0009]

According to the present invention, there are provided a tread portion, a sidewall portion extending inward from both ends thereof in a radial direction, and a bead portion located at an inner end portion in the radial direction of the sidewall portion. And a toroidal carcass that folds around the bead core through the tread portion and the sidewall portion, a belt layer disposed inside the tread portion and radially outside the carcass, and radially outside the belt layer. In the pneumatic tire provided with a band layer, the band layer is composed of a band ply in which band cords are arranged in parallel, and the band cords include a nylon strand formed by twisting a nylon filament and a polyester filament. Polyester stra formed by twisting the nylon filament in the same direction A pneumatic tire and the de orientation of the lower twist, characterized in that the ply-twisted in the opposite direction.

Nylon strands and polyester filaments each have a filament of 10 cm.
It is preferable that each twist is 20 to 60 times per twist, and that between the nylon strand and the polyester strand is 20 to 60 twists per 10 cm.

As the nylon filament, a filament made of nylon 66, nylon 6 or nylon 46 can be used, and as the polyethylene filament, a terephthalate filament can be preferably adopted.

[0012]

As described above, the band layer located on the outer side in the radial direction of the belt layer is formed by the band ply having the composite cord in which the nylon filament and the polyester filament are twisted together.

As shown in FIG. 3, the tensile properties of the fiber cord are that the initial elastic region a in which the elongation is relatively large at the initial load and the intermediate elastic region in which the elongation is smaller than that in the low elastic region a by further applying a load. There is a region b and a fracture deformation region c that occurs immediately before the fiber cord breaks.

In order to suppress lifting during high-speed running, it is necessary to use fibers having a small elongation in the intermediate elastic region b. As shown in FIG. 3 and Table 1, the polyester has a smaller elongation in the intermediate elastic region b than nylon, and therefore, by using the polyester, the lifting can be suppressed. The adhesiveness, that is, the heat-resistant adhesiveness, is low, and peeling occurs between the rubber and the rubber as the tire temperature rises.
Therefore, when the band cord is formed of only the polyester fiber, the high speed durability is not so improved due to the peeling of the cord.

[0015]

[Table 1]

Therefore, by forming a composite cord with a nylon filament as the band cord, the high elasticity in the intermediate elastic region of polyester is used to suppress lifting of the tread portion, while at the same time the nylon becomes hot in the tread portion. The adhesiveness with the rubber is maintained, the band cord is prevented from peeling, and the two are united to enhance the durability during high-speed running.

The nylon filament is twisted under to form a nylon strand, and the polyester filament is twisted under to form a polyester strand, and both strands are twisted over to form a band cord.

By forming the strands from filaments of the same kind in this way, the elastic modulus is low when a low load is applied, which causes vulcanization in the vulcanization mold of the raw tire and internal pressure inside the raw tire during molding. The outer peripheral surface of the tire can be pressed against the inner surface of the vulcanization mold along with the elongation of the band cord, and the tire can be easily vulcanized and molded while using a highly elastic filament such as polyester.

Regarding the inflection point between the initial elastic region and the intermediate elastic region found in the composite cord, whether the inflection point is high or low as long as the present invention is intended to prevent peeling of the band cord. There is no particular problem and there is no need to constrain it.

Further, since the band cord formed by using the polyester strand can impart a great hoop effect to the tread portion of the tire, it is possible to prevent lifting during high speed running. Moreover, the polyester strand has a lower passing noise than the conventional composite cord using the aromatic polyamide fiber, and can contribute to the noise reduction of the tire.

In addition, since the polyester filament is less expensive than the aromatic polyamide filament, the band cord can be economically produced and the tire cost can be reduced.

As described above, according to the present invention, by organically integrating the above-mentioned components, lifting during high speed traveling can be prevented, high speed durability can be improved, noise can be reduced, and an economical tire can be obtained. Can be provided.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, a pneumatic tire 1 has a sidewall portion 3 extending inward in the radial direction from both ends of a tread portion 2 and a bead portion 4 located at the radially inner end of the sidewall portion 3. , A toroidal carcass 6 that passes through the tread portion 2 and the sidewall portion 3 and folds around the bead core 5 of the bead portion 4, and the belt layer 7 is disposed inside the tread portion 2 and outside the carcass 6 in the radial direction. To be done. Further, a band layer 9 is arranged on the outer side of the belt layer 6 in the radial direction, and in this example, is arranged over substantially the entire width of the belt layer 7.

The carcass 6 is made up of one or more carcass cords in this embodiment, in which carcass cords are arranged at an angle of 70 to 90 ° with respect to the tire equator C, and in this example, one carcass ply. As the cord, an organic fiber such as nylon, rayon or aromatic polyamide is used.

The belt layer 7 uses belt cords made of steel or organic fibers such as nylon, rayon, aromatic polyamide or the like, and inner and outer two layers of belt plies 7A and 7B.
The belt cord is formed at an angle of 10 to 30 ° with respect to the tire equator C and the inner and outer belt plies 7A,
In 7B, they are oriented so as to be inclined in opposite directions. Belt layer 7
Belt width WB, which is the width of the tire in the axial direction, is tread portion 2
Is set to a range of 0.7 to 1.0 times the tread width WT, which is the distance in the tire axial direction between the edges E.

In the present embodiment, the band layer 9 is composed of two inner and outer layers, and the inner layer 9A disposed adjacent to the belt layer 7 covers the outer surface of the belt layer 7 substantially all over. It consists of a wide band ply having a width WS. On the other hand, the outer layer 9 </ b> B has a so-called hollow structure including two narrow band plies arranged outside the both ends of the belt layer 7.

Each of the band plies 10A and 10B constituting the inner layer 9A and the outer layer 9B is formed by coating a fabric in which the band cords 11 are arranged at an angle of 0 to 10 ° with respect to the tire equator C with a topping rubber. Form a sheet body.

The band cord 11 is a composite cord formed by a nylon filament 12 and a polyester filament 13. As shown in FIG. 2, a plurality of nylon filaments 11 are collectively twisted together to form a nylon strand 14 consisting of only the nylon filaments 12 ... A polyester strand 15 composed only of the polyester filaments 13 is formed.

Furthermore, these nylon strands 13
The band cord 11 is formed by twisting the polyester strand 14 and the polyester strand 14 together. In forming the nylon and polyester strands 14 and 15, there is no particular limitation on the number of denier and the number of bundles of the nylon and polyester filaments 12 and 13, but it is preferable that the nylon filament has a thickness of 840d or 1000d. Further, the number of threads for the upper twist of the nylon strand 14 and the polyester strand 15 can be appropriately set within a range in which the adhesive force between the nylon strand 14 and the topping rubber can be maintained during the upper twist.

Nylon and polyester strands 1
When forming Nos. 4 and 15, the twisting directions of the undertwisting of the filaments 12 and 13 are the same, and the number of twists at the time of undertwisting is in the range of 20 to 60 times per 10 cm. Nylon and polyester strands 14 and 15
In the twisting, that is, in the upper twisting, the twisting direction is preferably opposite to that of the lower twisting, and the number of twists of both strands 14 and 15 is preferably 20 to 60 times per 10 cm. However, it is not particularly necessary to match the number of twists in the lower twist.

In the lower twist and the upper twist, the number of twists is 20.
If it is less than 60, the filaments or strands may not be sufficiently bundled and become unstable as a composite cord, while if it exceeds 60, twisting becomes difficult during production and the composite cord becomes unstable.

In the lower twist and the upper twist, it is more preferable that the number of twists per 10 cm is in the range of 30 to 50 times. In addition, it is preferable that the number of band cords 11 to be driven is 40 to 60 per 10 cm during topping.

The band cord 11 formed in this way
Since the nylon strands 14 are always exposed on a part of the surface of the cord when the rubber is topping, the nylon strands 14 and the topping rubber are The adhesive strength of the band cord 11 is retained, and the band cord 11 can be prevented from peeling off. Moreover, since the polyester strand 15 strongly tightens the belt layer 7 with high elasticity, lifting can be prevented and high-speed durability can be increased.

Further, in this embodiment, after forming the hand cord or the fabric after the twisting, the adhesive treatment for further improving the adhesiveness of the polyester strand itself is performed.

For example, there is a treatment method in which the band cord 11 is impregnated with an epoxy resin, a pretreatment is performed, and then a tread of resorcinol-formadecit-latex is treaded. By performing such a treatment on the band cord 11 including the polyester filament, the adhesive force of the band cord 11 to the topping rubber can be further improved,
The band cord can be more reliably prevented from peeling off.

The band layer may be formed by a wide band ply 10A as shown in FIG. 4, and one or several band plies may be topped with the band cord according to the above-mentioned structure. It can also be formed by spirally winding a small-width and long strip-shaped ply formed by tilting the tire in the circumferential direction of the tire, and the present invention can be modified into various embodiments.

[0037]

SPECIFIC EXAMPLES Tires (Examples 1 and 2) having a tire size of 205 / 60R15 and having the structure shown in FIG. 1 and provided with a band layer having the specifications shown in Table 2 were tested and their performance was tested. did. The band cords made of nylon alone (Comparative Example 1), polyesters alone (Comparative Example 2) and composites of nylon and aramid fiber (Comparative Example 3) were also tested and their performances were compared.

The test conditions are as follows. a) High-speed durability Using a high-speed tester, apply an internal pressure of 2.1 kg / cm ² and a load of 515 kg to each tire, first run at a speed of 120 km / H for a certain period of time, and then gradually increase the speed. The distance traveled until the tread portion was damaged by repeating the running was shown as an index with Comparative Example 1 being 100. The larger the value, the better.

B) Passing noise Carried out by an actual vehicle coasting test specified in JASO C606, a vehicle equipped with test tires was passed over a straight test course at a passing speed of 60 km / H and a distance of 50 m while coasting. The passing noise was measured at a midpoint of the course by a stationary microphone placed at a distance of 7.5 m from the running center line and at a height of 1.2 m from the test road surface.
Is shown as an index. The larger the value, the less the passing noise and the better. The test results are shown in Table 2.

[0040]

[Table 2]

As a result of the test, it was confirmed that the high-speed durability of the example was higher than that of the comparative example.

[0042]

As described above, the pneumatic tire of the present invention is
A band having a band cord in which a band layer disposed outside the belt layer is twisted on a nylon strand formed by twisting a nylon filament and a polyester strand formed by twisting a polyester filament. Since it is formed of ply, high-speed durability is improved, and tire passing noise can be reduced as compared with a cord using a conventional aromatic polyamide fiber.

[Brief description of drawings]

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

FIG. 2 is a front view illustrating the band cord.

FIG. 3 is a graph showing the relationship between load and elongation of organic fibers used for band cords.

FIG. 4 is a cross-sectional view schematically showing another structure of the band layer.

[Explanation of symbols]

 2 tread part 3 sidewall part 4 bead part 5 bead core 6 carcass 7 belt layer 9 band layer 10 band ply 11 band cord 12 nylon filament 13 polyester filament 14 nylon strand 15 polyester strand

Claims (3)

[Claims] 1. A tread portion, a sidewall portion extending radially inward from both ends of the tread portion, and a bead portion located at an inner end portion of the sidewall portion in the radial direction. A toroidal carcass folded around a bead core through a wall portion, a belt layer arranged inside the tread portion and radially outside the carcass, and a band layer arranged radially outside the belt layer. A tire, wherein the band layer is composed of a band ply in which band cords are arranged in parallel, and the band cords are formed by twisting a nylon filament into a nylon strand and a polyester filament in the same direction as the nylon filament. The direction of the lower twist and the polyester strand formed by twisting Is a pneumatic tire characterized by being twisted in the opposite direction. 2. The pneumatic tire according to claim 1, wherein the nylon strands and the polyester strands are respectively twisted with a nylon filament or a polyester strand at a twist number of 20 to 60 times per 10 cm. 3. The nylon strand and the polyester strand are 20 to 60 per 10 cm of both strands.
The pneumatic tire according to claim 1 or 2, wherein the band cord is formed by performing upper twisting with a twist number of times.