JP4268464B2 - Pneumatic radial tire - Google Patents

Description

【００３８】
表の如く実施例のタイヤは、バンドコードの残存強力が高く、しかも優れたロードノイズ性能を発揮しながら高速耐久性が向上しているのが確認できる。
【００３９】
【発明の効果】
叙上のごとく本発明は、バンドコードを、ＰＥＮ繊維のストランドと他の有機繊維のストランドとの複合コードとしているため、バンドコードの残存強力を高く確保でき、しかも優れた振動・騒音性能を発揮しながらタイヤ耐久性を向上することができる。
【図面の簡単な説明】
【図１】発明の一実施例の空気入りラジアルタイヤを示すタイヤの断面図である。
【図２】帯状プライの構造を示す斜視図である。
【図３】バンドコードを誇張して示す線図である。
【符号の説明】
２ トレッド部
６ カーカス
７ ベルト層
９ バンド層
９Ａ バンドプライ
１０ バンドコード
１０Ａ 第１のストランド
１０Ｂ 第２のストランド[0001]
BACKGROUND OF THE INVENTION
The present invention uses a composite cord of polyethylene 2, 6 naphthalate fiber strands and other organic fiber strands as a band cord, thereby improving durability while exhibiting excellent vibration and noise performance. The present invention relates to a pneumatic radial tire.
[0002]
[Prior art]
In radial tires where the outer side of the carcass is tightened with a belt layer of steel cord, the so-called lifting phenomenon that bulges outward in the radial direction occurs in the tread due to the centrifugal force accompanying the tire rotation. In addition to inducing it, there is a problem in that high-speed durability is lowered, such as causing peeling damage starting from the outer edge of the belt layer.
[0003]
Therefore, conventionally, a band layer in which a nylon band cord is spirally wound is provided outside the belt layer to suppress the lifting phenomenon.
[0004]
However, with the recent improvement of the road network and the high performance of vehicles, the performance required for tires has become increasingly severe, and the generation of vibration and noise has become a major problem. Therefore, it has been proposed to employ polyethylene 2, 6 naphthalate (PEN) having a high elastic modulus for the band cord. (For example, refer to Patent Documents 1 and 2). This PEN cord increases the restraining force on the belt layer and suppresses the lifting phenomenon more, and increases the tread circumferential rigidity to make it difficult to pick up vibrations from the road surface. Seen [0005]
[Patent Document 1]
JP 9-30210 A [Patent Document 2]
Japanese Patent Publication No. 2002-29214
[Problems to be solved by the invention]
However, since the PEN cord has a higher elastic modulus than other organic fiber cords, it tends to be inferior in fatigue resistance, so that the strength of the cord after running is greatly reduced and it is necessary to improve it in terms of tire durability. There is. As a result of the present inventors' research, it has been found that the vibration / noise performance cannot be sufficiently improved with the cords of other organic fibers and the composite cords of other organic fibers.
[0007]
The present invention is based on the fact that the band cord is a composite cord of PEN fiber strands and other organic fiber strands, and is a pneumatic radial that can improve tire durability while exhibiting excellent vibration and noise performance. The purpose is to provide tires.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 of the present application is a pneumatic comprising a belt layer disposed inside a tread portion and outside a carcass, and a band layer disposed outside the belt layer. A radial tire,
The band layer is composed of one or more band plies in which a band cord is spirally wound at an angle of 5 degrees or less with respect to the tire circumferential direction,
The band cord comprises a first strand made of polyethylene 2,6 naphthalate fiber and twisted, and a second strand made of another organic fiber and twisted in the same direction, opposite to the twisted direction. It is characterized by being a composite cord that is twisted and twisted together.
[0009]
In the invention of claim 1, the composite cord is characterized in that the second strand is a nylon fiber, a polyethylene terephthalate fiber, or an aromatic polyamide fiber.
[0010]
In the invention of claim 1, the composite cord has an initial twist number n1 of the first strand of 30 to 45 times / 10 cm and an initial twist number n2 of the second strand of nylon fiber or polyethylene terephthalate fiber. 25 to 40 times / 10 cm, and 35 to 50 times / 10 cm for aromatic polyamide fibers, and the number N of upper twists is 35 to 45 times / 10 cm.
[0011]
In the invention of claim 1, the composite cord is characterized in that at least the number of lower twists n1 and the number of lower twists n2 are different.
[0012]
In the invention of claim 2, the composite cord is characterized in that the number of upper twists N is different from the number of lower twists n1 and n2.
[0013]
According to a third aspect of the present invention, the composite cord comprises: 150 to 350 fibers m1 of the first strand, 100 to 400 fibers m2 of the second strand, and polyethylene terephthalate fibers. 150 to 600 fibers and 500 to 1000 fibers for aromatic polyamide fibers.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a meridional section when the pneumatic radial tire of the present invention is a passenger tire.
[0015]
In FIG. 1, a pneumatic radial tire 1 (hereinafter referred to as a tire 1) includes a carcass 6 that extends from a tread portion 2 through a sidewall portion 3 to a bead core 5 of a bead portion 4, an inner side of the tread portion 2, and the carcass 6. The belt layer 7 disposed outside the belt layer 7 and the band layer 9 disposed further outside the belt layer 7 are configured.
[0016]
The carcass 6 is formed of one or more, in this example, one carcass ply 6A in which carcass cords are arranged at an angle of 75 to 90 ° with respect to the tire circumferential direction. The carcass ply 6 </ b> A includes ply folding portions 6 b that are folded from the inner side to the outer side in the tire axial direction around the bead core 5 on both sides of the ply main body portion 6 a that extends between the bead cores 5 and 5. A bead apex rubber 8 is provided between the ply body portion 6a and the ply turn-up portion 6b so as to taper outward from the bead core 5 in the radial direction, and is reinforced from the bead portion 4 to the sidewall portion 3.
[0017]
As a carcass cord, in the case of a tire for a passenger car, an organic fiber cord such as nylon, polyester, rayon, aromatic polyamide or the like is suitably employed, but a steel cord can also be employed depending on the tire size, category, or the like.
[0018]
The belt layer 7 is formed of two or more belt plies 7A and 7B in which high-strength belt cords such as steel cords are arranged at an angle of 15 ° to 40 ° with respect to the tire circumferential direction, in this example. Is done. Each belt ply 7A, 7B enhances belt rigidity by crossing the belt cords between the plies, and reinforces substantially the entire width of the tread portion 2 with a tagging effect.
[0019]
The ply width of the radially inner belt ply 7A is wider than that of the outer belt ply 7B, and this ply width constitutes the belt width WB of the belt layer 7.
[0020]
Next, the band layer 9 is formed from one or more band plies 9A, in this example, one band ply 9A, in which the band cord 10 is spirally wound at an angle of 5 degrees or less with respect to the tire circumferential direction. In this example, the case where the band ply 9A is a so-called full band that covers substantially the entire width of the belt layer 7 is illustrated. However, the band ply 9A is a pair of left and right so-called edge bands that cover only the outer end portion of the belt layer 7. The band layer 9 may be formed alone or in combination. As for the full band, “covering substantially the entire width” of the belt layer 7 means covering 95% or more of the belt width WB, and in this example, the width W of the band ply is the belt width WB. The case where it is substantially equal is illustrated.
[0021]
Further, as shown in FIG. 2, the band ply 9A includes a tape-like band-like ply 13 formed by embedding one band cord 10 or an aligned body of a plurality of band cords 10 in a topping rubber 12. It is formed by spirally winding along the circumferential direction, and at this time, the angle formed by the band cord 10 and the tire circumferential direction is set to 5 degrees or less. The band ply 9 </ b> A formed by such a spiral winding has a so-called jointless structure with no seam, so that it has excellent tire uniformity and increases the restraining force on the belt layer 7 to improve its tagging effect.
[0022]
In the present invention, as the band cord 10, as conceptually shown in FIG. 3, the first strand 10 </ b> A made of polyethylene 2, 6 naphthalate (PEN) fiber and twisted, and other organic fibers are used. And the 2nd strand 10B by which the lower strand was twisted in the same direction is formed with the composite cord of the double twist structure which twisted together by the upper twist in the direction opposite to the said lower twist.
[0023]
In addition, nylon fibers, polyethylene terephthalate (PET) fibers, or aromatic polyamide fibers are employed as other organic fibers forming the second strand 10B .
[0024]
Thus, the constructed composite cord exhibits excellent vibration and noise performance by the first strand 10A made of PEN fiber, and after traveling by the second strand 10B made of the other organic fiber. The strength reduction of the cord can be suppressed and the tire durability can be improved.
[0025]
Here, in the composite code,
(1) The number of primary twists n1 of the first strand 10A is 30 to 45 times / 10 cm;
(2) The number of twists n2 of the second strand 10B is
-25-40 times / 10 cm for nylon fiber or PET fiber,
-35-50 times / 10 cm for aromatic polyamide fibers;
(3) The number N of upper twists is 35 to 45 times / 10 cm
It is said .
[0026]
If the number of lower twists n1 and n2 and the number of upper twists N exceed the lower limit values, respectively, the fatigue resistance and impact resistance of the cord will be reduced, resulting in a deterioration in tire durability. On the contrary, when the upper limit value is exceeded, the strength and elastic modulus of the cord are reduced, and excellent vibration / noise performance cannot be exhibited.
[0027]
In particular, when the organic fiber of the second strand 10B is nylon or PET whose elastic modulus is lower than that of PEN, its lower twist number n2 is set to n2 <n1, and the elastic modulus is higher than that of PEN. In the case of a high aromatic polyamide, it is preferable that the number n2 of the lower twist is n2> n1 from the viewpoint of balancing the strength and durability of the first and second strands 10A and 10B. The difference in the number of twists | n1-n2 | is preferably in the range of 3-10. As described above, the composite cord has at least the lower twist number n1 and the lower twist number n2.
[0028]
Further, the number of upper twists N is preferably smaller than the number of lower twists nmax of the number of lower twists n1 and n2, from the viewpoint of balancing strength and durability. The difference (nmax−N) is preferably in the range of 1-15.
[0029]
When the composite cord is used for the band cord 10, the thickness of each strand 10A, 10B is preferably 500 to 2000 dtex, and if it is less than 500 dtex, the number of plies is increased in order to secure the band strength necessary for the tire. . On the other hand, if it exceeds 2000 dtex, the cord becomes thick and the ply thickness increases. The thickness d1 of the first strand 10A and the thickness d2 of the second strand 10B may be the same, but the thickness of the strand on the side where the elastic modulus of the fiber is low is high. It is preferable to make it smaller than the thickness of the strand on the side from the viewpoint of balancing strength and durability.
[0030]
In the composite cord, the number of PEN fibers m1 in the first strand 10A is in the range of 150 to 350, and the number of organic fibers m2 in the second strand 10B is in the range of 100 to 400 when nylon. It is preferably in the range of 150 to 600 for PET and in the range of 500 to 1000 for aromatic polyamide fiber. When the numbers m1 and m2 exceed the upper limit, the fibers are too thin, and tend to cause a reduction in the strength of the cord due to friction between the fibers. Conversely, when the lower limit is exceeded, the fibers are too thick. There is a problem with durability.
[0031]
The PEN fiber may be not only a homopolymer but also a copolymer composed of 85 mol% or more of polyethylene 2,6 naphthalate and less than 15 mol% of a copolymerizable third component. Examples of the third component include naphthalene dicarboxylic acid other than 2,6 naphthalene dicarboxylic acid, terephthalic acid, isophthalic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, and the like.
[0032]
As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.
[0033]
【Example】
A tire with a tire size of 195 / 65R15 having the structure shown in FIG. 1 was made on the basis of the specifications shown in Table 1, and the high speed durability, road noise, and remaining strength of the band cord of each sample tire were measured and compared.
The specifications of the carcass, belt layer, and band layer other than those in Table 1 are the same as follows.
・ Number of carcass plies: 2
Code: 1100 dtex (PET),
Cord angle: 90 degrees,
Number of cords driven: 38 / 5cm,
・ Number of belt layer plies: 2
Code: 1 x 3 x 0.27HT (steel),
Cord angle: +20 degrees / -20 degrees
Number of cords driven: 40 / 5cm,
・ Number of band layer plies: 1 (full band)
[0034]
(1) High speed durability;
Using a drum running tester, starting from 80 km / h with internal pressure (250 kPa) and load (2.45 kN), increasing the speed by 10 km / h every 10 minutes and running until damage The distance was expressed as an index with Comparative Example 1 as 100. The larger the value, the better.
[0035]
(2) Road noise;
It was mounted on all wheels of a passenger car (2000 cc) at an internal pressure (200 kPa), traveled on a smooth road surface at a speed of 60 km / h, and a sound pressure of 250 Hz and 315 Hz was measured at the position of the backrest of the driver's seat. The reciprocal of the value was displayed as an index with Comparative Example 1 as 100. The larger the value, the lower the road noise and the better.
[0036]
(3) Residual strength;
Using a drum testing machine, the vehicle was run at 10,000 km at a speed of 80 km / h under the conditions of the internal pressure specified by JIS and the maximum load specified by JIS, and the tire was disassembled after running to take out the band cord. And the load g at the time of a fracture | rupture was measured for the taken-out band cord based on 7.5 (tensile strength and elongation rate) of JIS L1017 (chemical fiber tire cord test method), and before rubber drawing (after DIP processing) ) In a ratio g / G to the load G at the time of breaking of the band cord in the state of). The larger the value, the higher the residual strength and the better the fatigue resistance.
[0037]
[Table 1]

[0038]
As shown in the table, it can be confirmed that the tires of the examples have a high residual strength of the band cord, and the high-speed durability is improved while exhibiting excellent road noise performance.
[0039]
【The invention's effect】
As described above, the present invention uses a band cord as a composite cord of PEN fiber strands and other organic fiber strands, so that the remaining strength of the band cords can be secured high, and excellent vibration and noise performance can be achieved. However, tire durability can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a tire showing a pneumatic radial tire according to an embodiment of the invention.
FIG. 2 is a perspective view showing a structure of a belt-like ply.
FIG. 3 is a diagram exaggeratingly showing a band code.
[Explanation of symbols]
2 Tread portion 6 Carcass 7 Belt layer 9 Band layer 9A Band ply 10 Band cord 10A First strand 10B Second strand

Claims (3)

A pneumatic radial tire comprising a belt layer arranged inside the tread and outside the carcass, and a band layer arranged outside the belt layer,
The band layer is composed of one or more band plies in which a band cord is spirally wound at an angle of 5 degrees or less with respect to the tire circumferential direction,
The band cord includes a first strand made of polyethylene 2,6 naphthalate fiber and twisted, and a second strand made of nylon fiber, polyethylene terephthalate fiber, or aromatic polyamide fiber and twisted in the same direction. , together with the said lower twisting a composite code by twisting and ply-twisted in the opposite direction,
The composite cord has an initial twist number n1 of the first strand of 30 to 45 times / 10 cm, an initial twist number n2 of the second strand of 25 to 40 times / 10 cm when nylon fiber or polyethylene terephthalate fiber and When it is an aromatic polyamide fiber, it is 35-50 times / 10 cm, and the upper twist number N is 35-45 times / 10 cm,
Moreover , the pneumatic radial tire is characterized in that the composite cord has at least the lower twist number n1 and the lower twist number n2 . The pneumatic radial tire according to claim 1 , wherein the composite cord has an upper twist number N different from the lower twist numbers n1 and n2. The composite cord has 150 to 350 fibers m1 of the first strand, 100 to 400 fibers m2 of the second strand fibers,
The pneumatic radial tire according to claim 1 or 2 , wherein the number is 150 to 600 for polyethylene terephthalate fibers and 500 to 1000 for aromatic polyamide fibers.

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