JP4499968B2 - Pneumatic radial tire - Google Patents

Description

【００２５】
この表１から明らかなように、実施例１はスチールベルト層を使用した比較例１に比べて乗り心地に優れ、しかも耐水圧強度やベルト層間剥離面観察については比較例４に比べて良好な結果が得られ、耐久性も優れていた。一方、ベルト層にポリオレフィンケトン以外の有機繊維コードを用いた比較例２，３は、耐水圧強度やベルト層間剥離面観察の結果が不十分であった。
【００２６】
【発明の効果】
以上説明したように本発明によれば、左右一対のビード部間にスチールコードを用いた少なくとも１層のスチールカーカス層を装架し、トレッド部におけるカーカス層の外周側に複数層のベルト層を埋設した空気入りラジアルタイヤにおいて、全てのベルト層に特定の条件を満足するポリオレフィンケトンの繊維コードを用いると共に、ベルト層の外周側に、特定の条件を満足するポリオレフィンケトンの繊維コードからなるベルトカバー層を配置したから、タイヤ重量を低減しつつ、耐久性と乗り心地を改善することができる。
【図面の簡単な説明】
【図１】本発明の実施形態からなる空気入りラジアルタイヤを示す半断面図である。
【符号の説明】
１ トレッド部
２ サイドウォール部
３ ビード部
４ カーカス層
５ ビードコア
６ａ，６ｂ ベルト層
７ ベルトカバー層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic radial tire using a polyolefin ketone fiber cord as a belt layer, and more particularly, to a pneumatic radial tire which eliminates the disadvantages of using a steel cord as a carcass layer.
[0002]
[Prior art]
In recent years, pneumatic radial tires using an ultra-high tensile steel cord for the carcass layer have been put on the market. Such a pneumatic radial tire has an advantage that its rolling resistance is particularly small in terms of performance. However, the tire is not only accompanied by an increase in weight due to the steel cords constituting the carcass layer, but there is a concern that the ride comfort may deteriorate due to an increase in rigidity.
[0003]
In order to eliminate such inconvenience, it is conceivable to use an organic fiber cord such as an aramid fiber in place of the steel cord for the belt layer embedded in the tread portion. However, in the pneumatic radial tire, since the tread portion is greatly deformed during running, the aramid fiber has insufficient adhesion to rubber, which is not preferable in practice.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to provide a pneumatic radial tire capable of improving durability and ride comfort while reducing tire weight.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a pneumatic radial tire according to the present invention has at least one steel carcass layer using a steel cord mounted between a pair of left and right bead portions, and is disposed on an outer peripheral side of the carcass layer in a tread portion. a pneumatic radial tire having embedded belt layer of the multiple layers, Rutotomoni using fiber cords made of filaments of a polyolefin ketone having the structure represented by all of the belt layer the following equation (1), the outer peripheral side of the belt layer In addition, a ribbon material in which at least one fiber cord composed of a polyolefin ketone filament having a structure represented by the following formula (1) is aligned and rubber-coated is continuously formed at substantially 0 ° with respect to the tire circumferential direction. A belt cover layer wound around is arranged .
[0006]
_{- (CH 2 -CH 2 -CO)} n- (R-CO) m- ··· (1)
Here, 1.05 ≧ (n + m) /n≧1.00,
R is an alkylene group having 3 or more carbon atoms.
[0007]
Thus, in the pneumatic radial tire having a carcass layer made of steel cords, by Rukoto have use a belt layer composed of the fiber cord polyolefin ketone satisfying specific conditions, while reducing the tire weight, and durability Riding comfort can be improved.
[0008]
In the present invention, in order to obtain a sufficient improvement effect on durability and ride comfort, at least one fiber cord comprising a polyolefin ketone filament having a structure represented by the above formula (1) on the outer peripheral side of the belt layer. It is preferable to dispose a belt cover layer formed by continuously winding a rubber-coated ribbon material substantially at 0 ° with respect to the tire circumferential direction.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
[0010]
FIG. 1 shows a pneumatic radial tire according to an embodiment of the present invention, where 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion. At least one carcass layer 4 is mounted between the pair of left and right bead portions 3, 3, and an end portion of the carcass layer 4 is folded around the bead core 5 from the inside to the outside of the tire. The carcass layer 4 is formed by aligning a plurality of steel cords so as to extend in the tire radial direction. The steel cord used for the carcass layer 4 preferably has a 1 × N twist structure. The steel cord preferably has a wire diameter of 0.10 to 0.25 mm and a carbon content of 0.9 to 1.1% by weight.
[0011]
Two belt layers 6 a and 6 b are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. The belt layer 6a located on the inner side of the tire and the belt layer 6b located on the outer side of the tire are obtained by arranging a plurality of polyolefin cord fiber cords. These belt layers 6a and 6b are arranged such that the cords are inclined with respect to the tire circumferential direction and the cords cross each other between the layers.
[0012]
In the present invention, using a fiber cords polyolefin ketone to all of the belt layer, it is possible to increase the total number of belt layers as needed. In either case, replacing the steel cord of the belt layer used in the past with the fiber cord of polyolefin ketone, which has excellent adhesion to rubber, reduces the weight of tires with a steel carcass layer and improves riding comfort. It becomes possible.
[0013]
On the outer peripheral side of the belt layers 6a and 6b, there is disposed a belt cover layer 7 having a polyolefin ketone fiber cord oriented in the tire circumferential direction. The belt cover layer 7 preferably has a jointless structure in which a ribbon material formed by aligning at least one fiber cord and covering with rubber is continuously wound substantially at 0 ° with respect to the tire circumferential direction. . The belt cover layer 7 is preferably composed of a full cover that covers the belt layers 6a and 6b over the entire width and an edge cover that covers only both ends of the belt layers 6a and 6b.
[0014]
Polyolefin ketone fibers used here are disclosed in JP-A-1-124617, JP-A-2-112413, US Pat. No. 5,194,210, JP-A-9-324377, JP-A-2001-115007, JP-A-2001. Although it can be obtained by melt spinning or wet spinning disclosed in JP-A-131825, etc., it is necessary to use a polyolefin ketone fiber having a structure represented by the following formula (1).
[0015]
_{- (CH 2 -CH 2 -CO)} n- (R-CO) m- ··· (1)
Here, 1.05 ≧ (n + m) /n≧1.00,
R is an alkylene group having 3 or more carbon atoms.
[0016]
In the formula (1), when the fraction of m (an alkylene unit other than ethylene) increases, the tire traveling growth increases and the durability decreases. This is presumably because the crystal structure of the spun fiber changes with an increase in m units, and the secondary binding force between the molecular chains decreases. In addition, when the strength of the fiber is lowered, the strength is further reduced when a twisted cord is used. Therefore, it is necessary to increase the amount of cord used to secure the breaking strength of the tire, and the provision of a lightweight and highly economical tire is provided. It becomes difficult. More preferably, an alternating copolymer consisting essentially of ethylene and carbon monoxide with m = 0 is preferably used. It is preferable to use wet spinning to produce such fibers.
[0017]
Further, as the fiber cord of polyolefin ketone, it is preferable to use a fiber cord having a tensile strength of 8.83 cN / dtex or more and an elongation at 1.99 cN / dtex of 3.5% or less. When the tensile strength is less than 8.83 cN / dtex, it is necessary to increase the number of fiber cords to be driven or to increase the thickness of the cords. However, when the number of drivings is too large, there is substantially no rubber between the cords, and adhesion failure between the belt layer (or belt cover layer) and the surrounding rubber tends to occur, resulting in a decrease in durability. On the other hand, if the cord becomes thick, the belt layer (or belt cover layer) becomes thick and it is difficult to ensure light weight. On the other hand, if the elongation at 1.99 cN / dtex exceeds 3.5%, it is difficult to ensure the rigidity of the belt layer, which causes a disadvantage in handling stability.
[0018]
The fiber cord of polyolefin ketone preferably has a twist coefficient K represented by K = T√ (D / 1.111) in the range of 1000 to 3500. Here, K is a twist coefficient, T is the number of twists of the cord (times / 10 cm), and D is the total number of decitex of the cord. When the twisting coefficient K is less than 1000, not only is it difficult to ensure fatigue resistance, but also the elongation at break is reduced and the resistance to trauma is deteriorated. When the twist coefficient K exceeds 3500, the modulus is greatly lowered, and it becomes difficult to ensure steering stability.
[0019]
【Example】
In the pneumatic radial tire having the tire size 205 / 55R16 89VA041 and the tire structure of FIG. 1, the steel cord is used for the carcass layer, while the types of cords constituting the belt layer and the belt cover layer are as shown in Table 1. Various pneumatic radial tires of Example 1, Reference Examples 1 and 2, and Comparative Examples 1 to 4 were produced. In addition, the following were used for the fiber cord of polyolefin ketone.
[0020]
POK fiber 1: polyolefin ketone (n + m) /n=1.07
Twist factor 1500, strength 9.27 cN / dtex,
1.9% elongation at 1.99 cN / dtex
POK fiber 2: Polyolefin ketone (n + m) /n=1.00
Twist factor 3500, strength 10.68 cN / dtex,
1.99cN / dtex elongation rate 3.5%
POK fiber 3: Polyolefin ketone (n + m) /n=1.00
Twist factor 1500, strength 12.71 cN / dtex,
1.6% elongation at 1.99 cN / dtex
With respect to these test tires, the ride comfort and water pressure resistance were evaluated by the following methods, and the belt delamination surface was observed. The results are shown in Table 1.
[0021]
Ride comfort:
The actual ride comfort evaluation (feeling relative evaluation) was performed by five drivers. The evaluation results were scored by a five-point method based on the following criteria in a relative comparison with a reference tire (Comparative Example 4), and expressed as the average score of three people excluding the highest and lowest points.
[0022]
Water pressure strength:
A water pressure was applied to the inside of the test tire, and the pressure when the tire was broken by increasing the water pressure was measured. The evaluation results are shown as an index with the reference tire (Comparative Example 4) as 100. It means that the greater the index value, the greater the water pressure resistance.
[0023]
Observation of belt delamination surface:
The test tire is mounted on a standard rim, and the inner pressure is 300 kPa, and the belt is removed from the tire by running 3000 km at a speed of 50 km / h on a drum provided with 10 cm high protrusions on the circumference. A delamination test was performed on the layer, and the state of the peeled surface was observed. The evaluation result is indicated by “OK” when the peeled surface is broken by rubber or when there is no difference between the protruding part and the non-overriding part. When the code part is exposed or the protruding part of the code is exposed “NG” indicates a case in which is increased compared to the non-overriding portion.
[0024]
[Table 1]

[0025]
As is apparent from Table 1, Example 1 is superior in ride comfort compared to Comparative Example 1 using a steel belt layer, and is also better than Comparative Example 4 in terms of water pressure resistance and belt delamination surface observation. The result was obtained and the durability was excellent. On the other hand, Comparative Examples 2 and 3 using organic fiber cords other than polyolefin ketone for the belt layer had insufficient results of water pressure resistance and observation of the belt delamination surface.
[0026]
【The invention's effect】
As described above, according to the present invention, at least one steel carcass layer using a steel cord is mounted between a pair of left and right bead portions, and a plurality of belt layers are formed on the outer peripheral side of the carcass layer in the tread portion. a pneumatic radial tire buried, using the fiber cord of polyolefin ketone satisfying specific conditions to all of the belt layers Rutotomoni, on the outer circumferential side of the belt layer, a fiber cord polyolefin ketone satisfying specific conditions belt Since the cover layer is disposed , durability and ride comfort can be improved while reducing the weight of the tire.
[Brief description of the drawings]
FIG. 1 is a half sectional view showing a pneumatic radial tire according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Carcass layer 5 Bead core 6a, 6b Belt layer 7 Belt cover layer

Claims (1)

In a pneumatic radial tire in which at least one steel carcass layer using a steel cord is mounted between a pair of left and right bead portions, and a plurality of belt layers are embedded on the outer peripheral side of the carcass layer in a tread portion , Rutotomoni using fiber cords made of filaments of a polyolefin ketone having the structure represented in the belt layer by the following equation (1), on the outer circumferential side of the belt layer, a polyolefin ketone having a structure represented by the following formula (1) A pneumatic radial tire in which a belt cover layer is formed by continuously winding a ribbon material, in which at least one fiber cord made of the above filament is aligned and rubber-coated, substantially at 0 ° with respect to the tire circumferential direction .
_{- (CH 2 -CH 2 -CO)} n- (R-CO) m- ··· (1)
Here, 1.05 ≧ (n + m) /n≧1.00,
R is an alkylene group having 3 or more carbon atoms.

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