JP2002079806A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire reducing rolling resistance and road noise. SOLUTION: This tire has a belt part comprising a first belt layer and a second belt layer arranged outside of the first belt layer in a tire radius direction, and a belt reinforcement layer arranged outside of the belt part in the tire radius direction. The belt reinforcement layer is made of plural rubber coated polyester fiber cords arranged in a line. The polyester fiber cords is spirally wound in a tire circumference direction to bet in parallel, an outermost end part A in a tire width direction of the belt reinforcement layer is placed between an outermost end part M of the first belt layer and an outermost end part N of the second belt layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having low rolling resistance, excellent steering stability, and greatly reduced road noise (in-vehicle noise).

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for improvement in rolling resistance and road noise in passenger car tires. The road noise is noise (in-vehicle noise) generated when the running tire picks up irregularities on the road surface, the vibration is transmitted to the inside of the vehicle, and the air in the vehicle vibrates. At present, several techniques for improving rolling resistance and road noise (in-vehicle noise) have been proposed.
Japanese Patent Application Publication No. 08-0808 proposes that the rigidity in the circumferential direction of the belt is strengthened by clamping a nylon fiber cord in which all or both ends of the cross belt are circumferentially arranged by a belt reinforcing layer formed by rubberizing. In addition, it has been proposed to spirally wind the belt reinforcing layer around the tire in order to eliminate the joint. The nylon fiber cord can be suitably used for the belt reinforcing layer in terms of adhesion to rubber, elongation characteristics, heat shrinkage, and the like. But,
In the case of the nylon fiber cord, since the elastic modulus is relatively low, the clamping force of the belt reinforcing layer cannot be sufficiently secured, and the rolling resistance and road noise (in-vehicle noise) of passenger car tires cannot be sufficiently improved. There is a problem.

As a cord in the belt reinforcing layer, a high-elastic fiber cord such as aramid fiber, carbon fiber or glass fiber is used instead of the nylon fiber cord, for example, as disclosed in Japanese Patent Application Laid-Open No. 2-147407.
It has been proposed in Japanese Patent Application Laid-Open No. 1-145203. However, in this case, although the road noise (in-vehicle noise) is improved as compared with the case where the nylon fiber cord is used, the shear distortion in the tire circumferential direction of the tread portion and the belt layer at the time of contact with the ground, and the belt layer are not. The rolling resistance deteriorates due to an increase in interlayer shear strain between the ends of the belt reinforcing layer. Further, since the fitting of the high elastic fiber cord to the mold at the time of vulcanization is not sufficient, the vulcanization moldability is poor, and a wide frequency band of 100 to 500 Hz, particularly 30
There is a problem that road noise (in-vehicle noise) in a relatively high frequency band of 0 to 500 Hz cannot be sufficiently reduced, the grounding property is not uniform, and steering stability and uneven wear resistance are significantly deteriorated. .

Recently, polyester fiber cords have been attracting attention as cords in the belt reinforcing layer. Among the polyester fiber cords, polyethylene terephthalate (hereinafter referred to as “PET”) suitable for reinforcing materials for tires such as carcass materials. Relatively high elasticity polyethylene-2,6- suitable for fields such as fiber, film and bottle
Naphthalate (hereinafter referred to as “PEN”) fiber cord
Particular attention has been paid.

[0005] As a cord in the belt reinforcing layer,
Polyethylene-2,6- instead of nylon fiber cord
The use of polyester fiber cords such as naphthalate (hereinafter referred to as "PEN") fibers can improve the rolling resistance, road noise (in-vehicle noise), and the like of the passenger car tire, for example, as disclosed in JP-A-9-66705.
No. pp. 147-64. However, recent requirements for rolling resistance and road noise (in-vehicle noise) are high, and even in this case, rolling resistance of passenger car tires,
The improvement effect of road noise (in-vehicle noise) is not a satisfactory level.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional problems and achieve the following objects. That is, an object of the present invention is to provide a pneumatic tire having low rolling resistance, excellent steering stability, and significantly reduced road noise (in-vehicle noise).

[0007]

Means for solving the above problems are as follows. That is, <1> a belt portion including a first belt layer and a second belt layer disposed radially outward of the first belt layer in the tire radial direction, and a belt reinforcing layer disposed radially outward of the belt portion in the tire radial direction. The belt reinforcing layer is obtained by rubberizing a plurality of polyester fiber cords arranged in a line, and is wound spirally so that the polyester fiber cords are substantially parallel to the tire circumferential direction. The outermost end portion A of the belt reinforcing layer in the tire width direction is the outermost end portion M of the first belt layer in the tire width direction and the outermost end portion N of the second belt layer in the tire width direction. And a pneumatic tire, wherein the pneumatic tire is located between the tires. <2> Polyester fiber cord is polyethylene-2,
The pneumatic tire according to <1>, which is a 6-naphthalate fiber cord.

[0008] The pneumatic tire according to <1>, wherein a belt portion including a first belt layer and a second belt layer disposed radially outward of the first belt layer in a tire radial direction, and a tire radius of the belt portion And a belt reinforcing layer disposed on the outside in the direction. In this pneumatic tire, the belt reinforcing layer is obtained by rubberizing a plurality of polyester fiber cords arranged in parallel, and spirally wound so that the polyester fiber cords are substantially parallel to the tire circumferential direction. Has been turned. Therefore, the polyester fiber cord having a high tension is arranged in the tire circumferential direction, and the tension rigidity of the tread portion in the tire circumferential direction is increased. As a result, the so-called tag effect of the belt layer is increased, so that it becomes difficult for the surface of the tread portion to pick up vibration due to unevenness of the road surface during tire running, and the vibration is sequentially transmitted to the tire side portion, the rim portion, and the wheel and transmitted to the vehicle interior. Vibration is reduced, and the road noise (in-vehicle noise) is reduced. In this pneumatic tire, the outermost end A of the belt reinforcing layer in the tire width direction is the outermost end M of the first belt layer in the tire width direction and the outermost end M of the second belt layer in the tire width direction. Outermost end N at
Is located between. In this case, the interlayer shear strain between the end of the first belt layer relatively moving in the tire circumferential direction and the belt reinforcing layer having small movement is effectively suppressed. As a result, the rolling resistance is greatly reduced. Also,
The belt reinforcement layer suppresses the vibration of the second belt layer which occurs when the second belt layer is stepped on and kicked out at the time of ground contact. As a result, road noise (in-vehicle noise) is significantly reduced.

[0009] In the pneumatic tire according to <2>, in <1>, the polyester fiber cord is a polyethylene-2,6-naphthalate fiber cord.
For this reason, compared with other high elastic fiber cords, the vulcanization moldability is good, and road noise (in-vehicle noise) in a wide frequency band of 100 to 500 Hz, particularly a relatively high frequency band of 300 to 500 Hz is obtained. It is sufficiently reduced, the contact property is uniform, and steering stability and uneven wear resistance are greatly improved. Further, since the stress-elongation curve is linear as compared with the composite fiber cord, the road noise (in-vehicle noise) does not deteriorate due to the magnitude of road surface input or the traveling speed, and is practical.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As an example of the structure of a pneumatic tire according to the present invention, a pair of beads, a carcass connected to the beads in a toroidal shape, and a crown of the carcass are crimped. A first belt layer, a second belt layer disposed on the first belt layer, a tread portion located on an outer peripheral side of a crown portion of the carcass, and inner positions of both ends of the tread portion or the entire tread portion. And a belt reinforcing layer disposed on the outer peripheral side of the second belt layer and reinforcing the first belt layer and the second belt layer, and further appropriately selected as necessary. It has other members.

In the pneumatic tire according to the present invention, the belt reinforcing layer is disposed at a position inside both ends of the tread portion and a position inside the entire tread portion and on the outer peripheral side of the second belt layer. There is a need. When the belt reinforcing layer is arranged as described above, in the pneumatic tire of the present invention, the tension rigidity in the tire circumferential direction of the tread portion is increased, and the so-called tag effect of the belt layer is increased. During running, it is difficult to pick up the vibration of the unevenness of the road surface on the surface of the tread,
Vibration transmitted to the rim and wheel sequentially to the interior of the vehicle is reduced as a whole, and the road noise (in-vehicle noise) is reduced.
Is reduced. On the other hand, if the belt reinforcing layer is not arranged as described above, a joint can be formed in the tire circumferential direction, a gap occurs between the upper and lower layers at the joint portion, and the uniformity is significantly deteriorated.

In the pneumatic tire of the present invention, the belt reinforcing layer is obtained by rubberizing a plurality of polyester fiber cords arranged in parallel so that the polyester fiber cords are substantially parallel to the tire circumferential direction. It must be spirally wound, and is preferably wound endlessly. If the polyester fiber cord is not spirally wound so as to be substantially parallel to the tire circumferential direction, the tire circumferential direction is not in a state where the polyester fiber cord having a high tension is arranged, and the tread portion is not provided. Has a low tensile rigidity in the tire circumferential direction. As a result, the so-called tag effect of the belt layer is not sufficient, and the surface of the tread portion easily picks up vibration due to unevenness of the road surface during running of the tire, and is sequentially transmitted to the tire side portion, the rim portion, and the wheel and into the vehicle. The transmitted vibration is not reduced, and the road noise (in-vehicle noise) is not reduced.

In the pneumatic tire of the present invention, the outermost end portion A of the belt reinforcing layer in the tire width direction is the outermost end portion M of the first belt layer in the tire width direction and the outermost end portion M of the second belt layer. Outermost end N in width direction
Must be located between When the outermost end portion A of the belt reinforcing layer in the tire width direction is located outside the outermost end portion M of the first belt layer in the tire width direction, that is, in a conventional tire structure which is conventionally present in many cases. If there is, the rolling resistance is deteriorated. When the outermost end portion A of the belt reinforcing layer in the tire width direction is located inside the outermost end portion N of the second belt layer in the tire width direction, when the second belt layer is stepped on the ground and kicked. Since the vibration generated at the time of pulling out cannot be completely suppressed by the belt reinforcing layer, the road noise (in-vehicle noise) deteriorates, and the rolling contact resistance also deteriorates at the same time as the grounding shape and the grounding pressure distribution deteriorate. Resulting in.

In the pneumatic tire of the present invention, the shape, structure, size, material, etc. of the bead portion, the carcass, the first and second belt layers, the tread portion, the belt reinforcing layer, and the like are as follows. There is no particular limitation, and it can be appropriately selected from known ones according to the purpose.

As the polyester fiber cord in the belt reinforcing layer, it is necessary that 90% or more of the total decitex number in the cord is a polyester fiber.
Preferably, 00% is polyester fiber. The fiber other than the polyester fiber in the polyester fiber cord is not particularly limited, and one or more kinds can be appropriately selected from known ones such as nylon fiber, aramid fiber, rayon fiber, and the like. .

The polyester fiber is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include polyethylene-2,6-naphthalate fiber and polyethylene terephthalate fiber. Among these, polyethylene is preferred because it has a high elastic modulus and is excellent in a belt circumferential clamping force which is a basic function of a belt reinforcing layer.
2,6-Naphthalate fibers are preferred. These polyester fibers may be used alone or in combination of two or more.

The polyethylene-2,6-naphthalate fiber is obtained, for example, by melt-spinning a resin chip of polyethylene-2,6-naphthalate (intrinsic viscosity 0.72). The conditions of the melt spinning are not particularly limited and may be appropriately selected depending on the purpose. For example, the spinning speed may be 600 m / min, and the ambient temperature immediately below the spinneret may be 340 ° C. Then, a heating cylinder having a length of 44 cm is set, and the spun unstretched yarn is wound by applying an oil agent with an oiling roller, and then the obtained unstretched yarn is pre-tensioned by 1%. Shrink heat setting is performed between a heated roll and a non-heated roll at a temperature of 2.2% at a relaxation rate of 2.2 ° C. and wound at 300 m / min to obtain a raw yarn of polyethylene-2,6-naphthalate fiber. In addition, the temperature of the spinning machine was set to 30 in the latter half of the extruder where the polymer was melted.
It is preferable that the temperature is about 0 to 315 ° C., and the temperature until the ink is discharged from the base is about 318 ° C. After passing through the heating tube, it is preferable to cool and solidify at a relative humidity of 65% and a temperature of 25 ° C. over a length of 35 cm.

The total decitex number D in the polyester fiber cord is 1100 to 5010 dtex.
Is preferable, and 2200-3340 dtex is more preferable. If the total decitex number D in the polyester fiber cord is less than 1100 dtex, the circumferential rigidity may be insufficient, and the effect of reducing road noise may be reduced (however, in this case, the number of cords and the belt reinforcing layer By increasing the number and the number of sheets, such a problem can be eliminated.) When the number exceeds 5010 dtex, the thickness of the belt reinforcing layer increases, the weight becomes too large, and the rolling resistance deteriorates. Circumferential rigidity is increased, and the effect of reducing road noise is increased, but the balance with rolling resistance may be poor.

The adhesive used for the polyester fiber cord in the belt reinforcing layer is not particularly limited and may be appropriately selected depending on the intended purpose. It may be a two-component reactive adhesive or a one-component reactive adhesive. It may be a type non-reactive adhesive.

The belt reinforcing layer can be manufactured according to a known method. For example, a polyester fiber cord obtained by applying the adhesive to the polyester fiber by a known method and then performing a heat treatment under known conditions. By arranging a plurality of these in parallel and rubberizing them by using an appropriately selected rubber, it can be manufactured in a belt shape.

[0021]

Hereinafter, embodiments of the present invention will be described.
The present invention is not limited to these examples.

(Examples 1 to 5 and Comparative Examples 1 to 3) Each of the pneumatic tires (radial tires) in Examples 1 to 5 and Comparative Examples 1 to 3 has a pair of bead portions and a pair of bead portions. A carcass formed in a toroidal shape, a first belt layer for clinching a crown portion of the carcass, a second belt layer disposed on the first belt layer, and a carcass located on an outer peripheral side of the crown portion of the carcass. A tread portion to be disposed and located at an inner position of both end portions of the tread portion or an inner position of the entire tread portion and on an outer peripheral side of the second belt layer, and reinforces the first belt layer and the second belt layer. And a belt reinforcing layer.

The pneumatic tire (radial tire) used in each of Examples 1 to 5 and Comparative Examples 1 to 3 was 205/6.
The pneumatic tire was manufactured under vulcanization conditions of 170 ° C. for 13 minutes and post-cure inflation conditions at an internal pressure of 2.5 kg / cm ² for 26 minutes.

In the pneumatic tire, the carcass has a number of twists of 1100 dtex / 2 (two twists of 1100 decitex) (primary twist × twist twist) 47 × 47.
(Times / 10 cm) using two polyethylene terephthalate cords, the number of shots is 55.0 lines / 5 cm
Was used. The carcass is arranged substantially in a direction perpendicular to the tire circumferential direction, and is composed of at least one layer.

In the pneumatic tire, two steel cord belts having a 1 × 5 × 0.23 structure are arranged as the belt layer, and the driving angles are 26 ° to the left and right with respect to the circumferential direction. 40.0 pieces / 5 cm was used. In the belt layer, non-extensible cords represented by aramid fibers and steel cords are arranged at an inclination angle of 10 ° to 30 ° with respect to the tire circumferential direction (or the equatorial plane of the tire). Are overlapped so as to cross in different directions.

The belt reinforcing layer is formed by rubberizing a plurality of polyester fiber cords arranged in parallel and has a narrow (about 5 to 20 mm) band shape.
As shown in Table 2, the polyester fiber cord was wound spirally (spirally) and endlessly so as to be substantially parallel (0 ° to 5 °) in the tire circumferential direction. In each of Examples and Comparative Examples, the outermost end A of the belt reinforcing layer in the tire width direction, the outermost end M of the first belt layer in the tire width direction, and the outermost end of the second belt layer in the tire width direction. The positional relationship with the outermost portion N is as shown in Tables 1 and 2.

The polyethylene-2,6-naphthalate fiber cord used for the belt reinforcing layer was produced as follows. That is, the yarn of the polyethylene-2,6-naphthalate fiber cord has a twist coefficient R of 0.20 to 0.2.
72, to obtain a twisted cord. The twisted cord was subjected to application of an adhesive and heat treatment under the following conditions to produce a polyethylene-2,6-naphthalate fiber cord. The application of the adhesive is described in JP-B-63
This was carried out by immersion in a resorcinol-formalin-latex adhesive shown in Example 1 of Example No.-12503. In the heat treatment, the treatment temperature in the drying zone is 170 ° C.
The processing time is 85 seconds, the processing temperature of the heat setting zone and the normalizing zone is 250 to 260 ° C., the processing time is 85 seconds, and the heat setting zone and the normalizing zone cord tension are 1.8 to 3.2 mN.
/ Dtex, and the tension ratio (H / N) between the heat set zone (H) and the normalizing zone (N) is 0.7 to
The test was performed under the condition of 1.05. Here, the cord physical properties after the application of the adhesive and after the heat treatment are 2.2.
Elongation under a load of 5 g / d (%) (JIS L1017-
1983) to 3.5% or less.

The following pneumatic tires (radial tires) in Examples 1 to 5 and Comparative Examples 1 to 3 were subjected to the following road noise test and rolling resistance test.

<Road noise test> Pneumatic tires (205 / 65R15, internal pressure 2.0 k) of each of the examples and comparative examples
gf / cm ² , rim size 6J-15 test tires) are mounted on a 2000cc displacement sedan type car with all four wheels, and two passengers are driven at a speed of 60km / h on the test course on the Road Nois evaluation road. A sound collecting microphone is attached to the center of the back of the driver's seat,
z and total sound pressure at 300 to 500 Hz frequency (Digibel)
Was measured. The index was displayed with the value of the control tire of Comparative Example 1 taken as 100. It is to be noted that the larger the value, the better the road noise property.

<Rolling Resistance Test> The rolling resistance was determined to be 1707.6 mm in outer diameter and 3 mm in width having a steel smooth surface.
Using a 50 mm rotating drum, under the action of a load of 300 kg, it was measured and evaluated by the coasting method when rotated at a speed of 0 to 180 km / hour. The speed was measured every 20 km / hour, evaluated by the average value of each speed, and the result was indicated as an index with the control tire of Comparative Example 1 as 100. The larger the value, the better (small) the rolling resistance.

[0031]

[Table 1]

[0032]

[Table 2]

As is clear from the results shown in Tables 1 and 2, the pneumatic tire of the present invention has extremely low rolling resistance and road noise as compared with the pneumatic tire of Comparative Example 1. On the other hand, in the pneumatic tires of Comparative Examples 2 and 3, the rolling resistance could not be reduced.

[0034]

According to the present invention, it is possible to provide a pneumatic tire having low rolling resistance, excellent steering stability, and significantly reduced road noise (in-vehicle noise).

[Brief description of the drawings]

FIG. 1 is a conceptual diagram for explaining an arrangement state of a belt reinforcing layer.

FIG. 2 is a conceptual diagram for explaining an arrangement state of a belt reinforcing layer.

FIG. 3 is a conceptual diagram for explaining an arrangement state of a belt reinforcing layer.

Claims (2)

[Claims] 1. A belt portion comprising a first belt layer and a second belt layer disposed radially outward of the first belt layer in a tire radial direction, and a belt reinforcing layer disposed radially outward of the belt portion in the tire radial direction. The belt reinforcing layer is obtained by rubberizing a plurality of polyester fiber cords arranged in a line, and spirally wound so that the polyester fiber cords are substantially parallel to the tire circumferential direction. The outermost end A of the belt reinforcing layer in the tire width direction.
Is located between the outermost end portion M of the first belt layer in the tire width direction and the outermost end portion N of the second belt layer in the tire width direction. 2. The pneumatic tire according to claim 1, wherein the polyester fiber cord is a polyethylene-2,6-naphthalate fiber cord.