JP3848790B2 - Pneumatic radial tire - Google Patents

Description

【００２０】
【表２】

【００２１】
【表３】

【００２２】
表１〜表３において、比較例１〜２、比較例４、比較例７〜８、比較例１１はＮＥ、ＮＦをベルト層の外側に配置した場合であり、比較例３および比較例５はＮＦをベルト層の外側に配置した場合であり、比較例６はＮＥ、ＮＦをベルト層の内側に配置してはいるがベルト層のコード径が大き過ぎる場合であり（０．６５ｍｍ）、比較例９はＮＥ、ＮＦをベルト層の内側に配置してはいるがベルト層のコード径が小さ過ぎる場合であり（０．２０ｍｍ）、比較例１０ＮＥをベルト層の内側に配置してはいるがベルト層のコード径が小さ過ぎる場合である（０．２０ｍｍ）。
【００２３】
表１〜表３から明らかなように、本発明の場合（実施例１〜１０）には比較例１〜１１に比してベルト層の耐コード折れ性および耐ベルトエッジセパレーション性に優れていることが判る。
【００２４】
【発明の効果】
以上説明したように、本発明によれば、トレッドのカーカス層の外側に単線スチールコードからなるベルト層を配置した空気入りラジアルタイヤにおいて、前記カーカス層と前記ベルト層との間に、最大幅ベルト層の幅方向端部を超えてタイヤ幅方向に延びる有機繊維コードからなるバンド層をコードがタイヤ周方向に実質的に平行に配置したために、ベルト層の耐コード折れ性を向上させると共にベルトエッジセパレーションの発生を抑制することが可能となる。
【図面の簡単な説明】
【図１】本発明の空気入りラジアルタイヤの一例を示すタイヤ子午線方向半断面説明図である。
【図２】本発明の空気入りラジアルタイヤの要部を示す展開平面図である。
【符号の説明】
１ ビードコア ２ カーカス層 ３ トレッド ４ｕ 上側ベルト層４ｄ 下側ベルト層 ７ バンド層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic radial tire that improves the cord fold resistance of a belt layer and suppresses belt edge separation.
[0002]
[Prior art]
Conventionally, steel cords having excellent tensile strength and elastic modulus have been used for the belt layer of pneumatic radial tires. This steel cord is a 1 × 2 or 1 × 3 stranded wire cord formed by twisting two or three filaments, and 2 + 2 formed by twisting two filaments outside the two filaments Although a stranded wire cord having a structure has been used, recently, a single wire cord has come to be used from the viewpoint of reducing the cord production cost and reducing the weight of the tire.
[0003]
Since the single wire cord does not have a twisting process compared to the stranded wire cord, the cord production cost can be greatly reduced. In addition, since the single wire cord does not have a useless space called a gap between filaments unlike the stranded wire cord, the diameter is smaller than that of the stranded wire cord, so the amount of rubber composition (coat rubber) used to coat the steel cord is used. The weight of the tire can be reduced, and the belt layer covered with the coat rubber is completely covered with the coat rubber, so the cord is corroded by water penetration and the adhesion between the cord and the coat rubber is reduced. Can be prevented.
[0004]
However, the single wire cord is rigid because it is not twisted compared to the stranded wire cord, and is less likely to be broken because the elongation in the longitudinal direction and the width direction is less like the stranded wire cord, and at the belt layer width direction end There is a problem that separation (peeling of the cord and coat rubber, belt edge separation) easily occurs, thereby reducing belt durability.
[0005]
Therefore, with regard to pneumatic radial tires using single-wire steel cords for the belt layer, further improvements in belt durability have been demanded with the recent increase in the speed of vehicles.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a pneumatic radial tire using a single-wire steel cord for the belt layer, which improves the cord layer resistance to breakage of the belt layer and suppresses the occurrence of belt edge separation.
[0007]
[Means for Solving the Problems]
The present invention relates to a pneumatic radial tire in which a belt layer made of a single wire steel cord is disposed outside a carcass layer of a tread, and the single wire steel cord has a cord diameter of 0.25 to 0.60 mm, and the belt The layer is formed by arranging the single wire steel cords at a cord angle of 15 ° to 35 ° with respect to the tire circumferential direction and 35 to 135 embeddings per 50 mm in width, and between the carcass layer and the belt layer. in, wherein the encoding band layer made of organic fiber cords extending in the tire width direction beyond the width direction end portion of the maximum width belt layer is arranged so as to be substantially parallel to the tire circumferential direction .
[0008]
Since the band layer made of organic fiber cords is disposed between the carcass layer and the belt layer in this way, the band layer acts as a cushioning material so that the movement of the carcass layer is difficult to be transmitted to the belt layer and the belt layer width direction terminal. Therefore, it is possible to improve the cord fold resistance of the belt layer and to suppress the occurrence of belt edge separation (improve belt edge separation resistance).
[0009]
DETAILED DESCRIPTION OF THE INVENTION
In FIG. 1, the end of the carcass layer 2 is wound around the pair of left and right bead cores 1, 1 from the inside of the tire to the outside, and the lower belt layer 4 d and the upper side are disposed outside the carcass layer 2 in the tread 3. Two belt layers with the belt layer 4u are arranged over the circumference of the tire in the tire circumferential direction. A main groove 5 extending in the tire circumferential direction is provided on the surface of the tread 3.
[0010]
The two belt layers 4d, 4u are each made of a single wire steel cord 6, as shown in FIG. In these belt layers 4d and 4u, the cords cross each other between the plies. Three or more belt layers may be arranged.
[0011]
The single wire steel cord 6 may have a cord diameter of 0.25 to 0.60 mm. This is because if the cord diameter is less than 0.25 mm, the cord becomes too thin and the cord breakage resistance and the belt edge separation resistance decrease, while if it exceeds 0.60 mm, the ride comfort is deteriorated.
[0012]
The cord angle of the single wire steel cord 6 with respect to the tire circumferential direction EE ′ is preferably 15 ° to 35 °. Cord breakage of the belt layer is caused by buckling deformation (buckling) of the tire ground contact surface, but when the single wire steel cord is made at such a high angle (15 ° to 35 °), the cord tension of the belt layer increases. This is because the buckling amount can be reduced, which is effective in improving the cord fold resistance of the belt layer.
[0013]
The number of embedded single wire steel cords 6 (number of ends) in each of the two belt layers 4d and 4u is preferably 35 to 135 per 50 mm of the belt layer width. If the number is less than 35, sufficient belt rigidity cannot be secured, while if it exceeds 135, the belt weight is too large and the belt weight increases.
[0014]
Between the carcass layer 2 and the belt layer (the belt layer adjacent to the carcass layer 2, that is, the lower belt layer 4d), as shown in FIG. 1 and FIG. 2, the maximum width belt layer (lower belt layer 4d) A band layer 7 made of an organic fiber cord extending in the tire width direction beyond the end portion in the width direction is disposed so that the cord 7a is substantially parallel (substantially 0 °) to the tire circumferential direction EE ′.
[0015]
The band layer 7 is formed by embedding an organic fiber cord in a coated rubber. As shown in FIGS. 1 and 2, the band layer 7 may be a single layer or two or more layers. The belt layer may be disposed over the entire width of the belt layer (hereinafter referred to as a full cover), or may be disposed only at both ends in the width direction of the belt layer (hereinafter referred to as an edge cover). The arrangement may be a combination of a full cover and an edge cover.
[0016]
The organic fiber cord is not particularly limited. For example, a polyamide fiber cord or a polyester fiber cord may be used. The polyamide fiber cord is, for example, an aliphatic polyamide fiber cord such as a nylon fiber cord or an aromatic polyamide fiber cord such as an aramid fiber cord.
[0017]
【Example】
Pneumatic radial tires having tire dimensions of 175/65 R14 and having the specifications shown in Table 1, Table 2, and Table 3 in which two belt layers made of a single wire steel cord were arranged were produced (Examples 1 to 10, Comparative Examples 1-11).
[0018]
After mounting these tires on the vehicle and traveling 30,000 km on mountain roads including bad roads, disassemble the mounted tires and visually inspect the belt layer for cord breakage and visually check for belt edge separation. I investigated. The results are shown in Table 1, Table 2, and Table 3. In these tables, “NE” is an edge cover made of nylon fiber cord, and “NF” is a full cover made of nylon fiber cord. “1B” represents the first belt layer counted in the tread direction from the carcass layer (carcass layer adjacent belt layer), and “1B, 2B” represents the first belt layer and the second belt layer. Represent. Note that “1B inside” in the term of edge separation means edge separation on the carcass layer side of the first belt layer.
[0019]
[Table 1]

[0020]
[Table 2]

[0021]
[Table 3]

[0022]
In Tables 1 to 3, Comparative Examples 1-2, Comparative Example 4, Comparative Examples 7-8, and Comparative Example 11 are cases where NE and NF are arranged outside the belt layer. Comparative Examples 3 and 5 are This is a case where NF is arranged outside the belt layer. In Comparative Example 6, NE and NF are arranged inside the belt layer, but the cord diameter of the belt layer is too large (0.65 mm). In Example 9, NE and NF are arranged inside the belt layer, but the cord diameter of the belt layer is too small (0.20 mm), and Comparative Example 10 NE is arranged inside the belt layer. This is a case where the cord diameter of the belt layer is too small (0.20 mm).
[0023]
As is apparent from Tables 1 to 3, in the case of the present invention (Examples 1 to 10), the belt layer is superior in cord break resistance and belt edge separation resistance as compared with Comparative Examples 1 to 11. I understand that.
[0024]
【The invention's effect】
As described above, according to the present invention, in a pneumatic radial tire in which a belt layer made of a single wire steel cord is disposed outside a carcass layer of a tread, a maximum width belt is provided between the carcass layer and the belt layer. The band layer made of organic fiber cords extending in the tire width direction beyond the width direction end of the layer is arranged substantially in parallel with the tire circumferential direction, so that the cord layer is improved in cord folding resistance and the belt edge Generation of separation can be suppressed.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a tire meridian half-sectional explanatory view showing an example of a pneumatic radial tire of the present invention.
FIG. 2 is a developed plan view showing a main part of the pneumatic radial tire of the present invention.
[Explanation of symbols]
1 Bead core 2 Carcass layer 3 Tread 4u Upper belt layer 4d Lower belt layer 7 Band layer

Claims (2)

In a pneumatic radial tire in which a belt layer made of a single wire steel cord is arranged outside a carcass layer of a tread, the single wire steel cord has a cord diameter of 0.25 to 0.60 mm, and the belt layer is a single wire The steel cord is arranged with a cord angle of 15 ° to 35 ° with respect to the tire circumferential direction and an embedding number of 35 to 135 per 50 mm in width, and further, the maximum width between the carcass layer and the belt layer. a pneumatic radial tire cord band layer made of organic fiber cords extending in the width tire width direction beyond the axial end portion is arranged so as to be substantially parallel to the tire circumferential direction of the belt layer. The pneumatic radial tire according to claim 1 , wherein the organic fiber cord is a polyamide fiber cord or a polyester fiber cord.

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