JP2010269675A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire for attaining both of excellent various performance such as steering stability and high quality of the tire. <P>SOLUTION: This pneumatic tire 10 includes at least a sheet of angled belt layer 6 and an auxiliary belt layer 7 arranged at substantially 90°C in a tire peripheral direction. This auxiliary belt layer 7 is reinforced by a cord made of twine prepared by doubling the plurality of first twisted yarns and applying final twists in a direction opposite to that of the first twists at a final twist coefficient N2 defined by formula: N2=n2×√(0.125×D2/ρ)×10<SP>-3</SP>after applying first twists at a first twist coefficient N1 defined by formula: N1=n1×√(0.125×D1/ρ)×10<SP>-3</SP>. The first twist coefficient N1 and the final twist coefficient N2 satisfy formula: 0.95≤N2/N1≤3.00, and the final twist coefficient N2 satisfies formula: 0.55≤N2≤1.10. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pneumatic tire (hereinafter, also simply referred to as “tire”), and more particularly, to a pneumatic tire that highly balances various performances and quality of a tire including steering stability.

  Currently, the belt commonly used as a reinforcing member of a carcass forming a skeleton of a radial tire for a passenger car, in particular, a reinforcing member of a crown portion of a carcass, is mainly composed of a rubberized layer of a steel cord that is inclined with respect to the equator plane of the tire. Two or more steel belt layers are used, and the steel cords in these belt layers intersect each other.

  In addition, the stability of the tire during running of the tire, particularly the stability during high speed running, and further the peeling of the belt layer during high speed running, particularly the peeling that occurs remarkably at the end of the belt layer, prevents the durability of the tire. In order to improve the property, a belt protective layer formed by rubberizing an organic fiber cord in the tire circumferential direction may be disposed outside the belt in the tire radial direction. As the structure of such a belt protective layer, a so-called cap structure or layer structure is known.

  Further, conventionally, as a technique for improving performance in a pneumatic tire, a floating belt structure including an auxiliary belt layer disposed substantially at 90 ° with respect to the circumferential direction of the tire is known (for example, Patent Document 1). reference). Since this structure can make the distribution in the width direction of slip and tangential force between the outer surface of the tire tread and the road surface, steering stability and uneven wear resistance can be improved. In the main floating belt structure, a belt auxiliary layer made of organic fibers is arranged along a belt layer immediately below (see FIG. 1).

JP 2007-331424 A

  According to the above-described floating belt structure, various performances such as steering stability and uneven wear resistance of a pneumatic tire can be improved, but today, it is desired that tire performance and quality are more highly compatible. ing.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic tire that is highly compatible with various performances and quality of a tire including steering stability.

  As a result of diligent investigation focusing on the auxiliary belt layer in the pneumatic tire having a floating belt structure in order to make the performance and quality of the tire highly compatible, the present inventors found that the tire is in the width direction during tire vulcanization. However, if the shrinkage rate of the auxiliary belt layer is smaller than the shrinkage rate of the tire, it was found that the belt could not follow and undulate in the radial direction and the circumferential direction. It has been found that this undulation affects not only the quality of the tire but also the quality, but also the steering stability, which is a feature of the floating belt structure, is impaired due to uneven rigidity in the auxiliary belt layer. . The present invention has been completed as a result of further intensive studies based on such findings.

That is, the pneumatic tire according to the present invention has a carcass extending in a toroidal shape between a pair of left and right bead portions, and at least one angled belt layer and a tire periphery sequentially in the tire radial direction of the carcass. In a pneumatic tire comprising an auxiliary belt layer disposed substantially at 90 ° with respect to the direction,
The cord of the auxiliary belt layer has the following formula (I),
N1 = n1 × √ (0.125 × D1 / ρ) × 10 ⁻³ (I)
(N1 is the number of lower twists (times / 10 cm), D1 is the indicated decitex number of the lower twisted yarns, and ρ is the specific gravity (g / cm ³ ) of the organic fiber). After twisting, the plurality of the lower twisted yarns are aligned and in the opposite direction to the lower twist, the following formula (II),
N2 = n2 × √ (0.125 × D2 / ρ) × 10 ⁻³ (II)
(N2 is the number of upper twists (times / 10 cm), D2 is the total display decitex number, and ρ is the specific gravity (g / cm ³ ) of the organic fiber.) It consists of a twisted yarn, and the lower twist coefficient N1 and the upper twist coefficient N2 are represented by the following formula (III),
0.95 ≦ N2 / N1 ≦ 3.00 (III)
And the upper twist coefficient N2 is the following formula (IV),
0.55 ≦ N2 ≦ 1.10 (IV)
It is a cord twisted so as to satisfy the above.

  In the present invention, the cord constituting the carcass is preferably an organic fiber, and in the present invention, the total fineness of the cord of the auxiliary belt layer is preferably 1000 to 9000 dtex. In this case, it is preferable that the dry heat shrinkage of the cord of the auxiliary belt layer is 10 to 15%. In the present invention, a belt protective layer wound in a spiral shape in the tire circumferential direction and covering both ends of the auxiliary belt layer can be suitably provided.

  According to the present invention, it is possible to provide a pneumatic tire in which various performances and quality of a tire including steering stability are highly compatible.

It is sectional drawing which shows the pneumatic tire which concerns on one embodiment of this invention. (A) is a top view which shows the lamination | stacking state of the crossing belt layer which concerns on one embodiment of this invention, an auxiliary | assistant belt layer, and a belt protective layer, (b) is typical sectional drawing which shows the same lamination | stacking state FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail.
FIG. 1 shows a schematic cross-sectional view of an example of a pneumatic tire according to an embodiment of the present invention. The illustrated tire 10 includes a tread portion 1, a pair of sidewall portions 2 extending inward in the tire radial direction from both ends thereof, and a pair of bead portions 3 positioned at the inner ends thereof. A carcass 5 composed of a single carcass ply (one in the illustrated example) is extended in a toroidal shape between a pair of bead cores 4 embedded in the bead portion 3.

  In the tire 10, as shown in FIG. 2, a belt 6 including at least one belt ply (in the illustrated example, two crossing belt layers 6 a and 6 b) on the outer side of the crown portion of the carcass 5 in the tire radial direction, An auxiliary belt layer 7 disposed substantially at 90 ° with respect to the circumferential direction, and a belt protective layer 8 that covers both ends of the auxiliary belt layer 7 and is spirally wound in the tire circumferential direction are sequentially disposed. Yes.

In the present invention, the cord of the auxiliary belt layer 7 is represented by the following formula (I),
N1 = n1 × √ (0.125 × D1 / ρ) × 10 ⁻³ (I)
(N1 is the number of lower twists (times / 10 cm), D1 is the indicated decitex number of the lower twisted yarns, and ρ is the specific gravity (g / cm ³ ) of the organic fiber). After twisting, the plurality of the lower twisted yarns are aligned and in the opposite direction to the lower twist, the following formula (II),
N2 = n2 × √ (0.125 × D2 / ρ) × 10 ⁻³ (II)
(N2 is the number of upper twists (times / 10 cm), D2 is the total display decitex number, and ρ is the specific gravity (g / cm ³ ) of the organic fiber.) It is made of a twisted yarn, and the lower twist coefficient N1 and the upper twist coefficient N2 are represented by the following formula (III),
0.95 ≦ N2 / N1 ≦ 3.00 (III)
And the upper twist coefficient N2 is the following formula (IV),
0.55 ≦ N2 ≦ 1.10 (IV)
It is important that the cord is twisted so as to satisfy the above.

  When the cord of the auxiliary belt layer 7 satisfies the above conditions, the dry heat shrinkage rate of the cord increases. Thereby, when the auxiliary belt layer 7 contracts in the cord direction, it is possible to follow the contraction of the entire tire. For this reason, the waviness in the radial direction and the circumferential direction that occurs in the conventional auxiliary belt layer does not occur, the quality is excellent, and the steering stability can be improved.

  Here, when the ratio N2 / N1 of the lower twist coefficient N1 and the upper twist coefficient N2 of the cord of the auxiliary belt layer 7 is less than 0.95, the twist torque generated by the lower twist becomes excessive, and the cord properties are extremely poor. It becomes stable. On the other hand, when it is larger than 3.00, the twisting torque generated by the lower twist becomes large, and the cord properties are also unstable.

  Further, when the upper twist coefficient N2 of the cord of the auxiliary belt layer 7 is less than 0.55, the fatigue resistance required for the cord of the auxiliary belt layer is lowered, resulting in a problem that the tire durability is lowered. . On the other hand, if it is greater than 1.10, the cord properties become extremely unstable, so that the fatigue resistance is also lowered.

  In the present invention, the carcass cord is preferably an organic fiber. By using the organic fiber as the carcass cord, the shrinkage ratio of the entire tire and the shrinkage ratio of the auxiliary belt layer 7 can be brought close to each other, and the manufacture of a tire having excellent quality is facilitated.

  In the present invention, the total fineness of the cord of the auxiliary belt layer 7 is preferably 1000 to 9000 dtex. If the total fineness of the cord is less than 1000 dtex, both the elastic modulus and the heat shrinkage stress are insufficient. On the other hand, if it exceeds 9000 dtex, the cord diameter becomes thick and the driving cannot be made dense.

Furthermore, in the present invention, the dry heat shrinkage rate of the cord of the auxiliary belt layer 7 is preferably 10 to 15%. The reason why the dry heat shrinkage rate of the organic fiber used for the cord of the auxiliary belt layer 7 is in the range of 10 to 15% is that if this value is less than 10%, the shrinkage at the time of vulcanization cannot be followed, while 15% This is because, when the heat shrinkage occurs, there is a concern that undulation and horn are likely to occur due to the shrinkage of the cord itself. Further, when the dry heat shrinkage of the organic fiber used for the auxiliary belt layer 7 is 10 to 15%, the steering stability is also improved. The dry heat shrinkage in the present invention is a value obtained by the following equation by performing a dry heat treatment at 160 ° C. for 30 minutes in an oven and measuring the fiber length before and after the heat treatment with a load of 50 g.
Dry heat shrinkage (%) = (Lb−La) / Lb × 100
However, Lb is the fiber length before heat treatment, and La is the fiber length after heat treatment.

  Preferable examples of the organic fiber material used for the auxiliary belt layer 7 include polyamides such as 66 nylon (66Ny) and 6 nylon (6Ny).

  The organic fiber cord constituting the auxiliary belt layer 7 is preferably subjected to a treatment with an adhesive solution. Such treatment with an adhesive solution is a conventionally known immersion or coating treatment in an adhesive solution, and as the adhesive solution, for example, a resorcin-formaldehyde condensate / rubber latex mixed solution is generally used. is there. The organic fiber cord used in the present invention is a heat set zone or a normalizer in an adhesive heat treatment method for a rubber organic fiber cord which is passed through a drying zone, a heat set zone and a normalizing zone after being immersed in an adhesive solution or applied. Good adhesiveness with rubber can be obtained by appropriately changing the processing temperature of the rising zone. Moreover, a desired dry heat shrinkage rate can be obtained by appropriately changing the processing tension of the heat setting zone or the normalizing zone.

  In the present invention, the belt 6 is preferably a two-layer (6a, 6b) crossing belt that is inclined in opposite directions with respect to the equator direction (circumferential direction). The code type, the inclination angle, and the number of driving can be appropriately selected from a known range, and are not particularly limited as long as a desired tag effect is obtained.

  Further, in the present invention, it is preferable to provide the belt protective layer 8 because a tire failure due to belt end separation can be prevented. As shown in FIG. 2, the belt protective layer 8 has a so-called layer structure disposed on both ends of the auxiliary belt layer 7. The belt protective layer 8 is formed by spirally winding a thin ribbon-like sheet obtained by rubberizing two or more reinforcing elements having a width smaller than the arrangement width until the arrangement width is reached. Preferably formed. By forming the protective layer 8 by continuously winding the ribbon-like sheet, a joint portion does not occur in the tire circumferential direction, and the belt 6 and the auxiliary belt layer 7 can be uniformly reinforced. .

  In the present invention, as long as the auxiliary belt layer 7 has the above-described configuration, the other tire structures and materials are not particularly limited, and can be appropriately set according to a conventional method. For example, the carcass 5 is formed of one organic fiber ply cord in the illustrated example, but may be provided by two or more. Although not shown, an inner liner is usually disposed in the innermost layer of the tire, and a tread pattern is appropriately formed on the tread surface. In the pneumatic tire of the present invention, as the gas filled in the tire, normal or air having a changed oxygen partial pressure, or an inert gas such as nitrogen can be used.

Hereinafter, the present invention will be specifically described based on examples.
(Examples 1 to 10, conventional examples and comparative examples 1 to 3)
Using the cords shown in the following Tables 1 to 3 for the auxiliary belt layer, tires of size 215 / 45ZR17 were manufactured, and the disturbance of the auxiliary belt layer and the steering stability were evaluated by the following methods. The dry heat shrinkage rate in the table is changed by changing the twist coefficient and changing the treatment temperature and treatment tension of the heat setting zone or normalizing zone in the fiber cord adhesive treatment to the conditions shown in the table. It was.

(Auxiliary belt layer disturbance)
Each test tire was dissected and the disturbance of the auxiliary belt layer was evaluated visually.

(Maneuvering stability)
Each test tire was mounted on an actual vehicle, and the driving stability was evaluated by the driver's feeling running on a dry circuit (dry). The results are shown as an index with the conventional example as 100. The larger the value, the better the steering stability and the better.

※１：オーブン中で１６０℃、３０分の乾熱処理を行ない、熱処理前後の繊維長を、５０ｇの荷重をかけて計測して下式により求められる値である。
乾熱収縮率（％）＝（Ｌｂ−Ｌａ）／Ｌｂ×１００
ただし、Ｌｂは熱処理前の繊維長、Ｌａは熱処理後の繊維長である。
※２：ヒートセットゾーンおよびノルマライジングゾーンの処理温度で従来例を１００とした指数表示である。数値が大なるほど高温であることを示す。
※３：ヒートセットゾーンおよびノルマライジングゾーンの処理張力で従来例を１００とした指数表示である。数値が大なるほど高張力であることを示す。

* 1: A value obtained by the following equation by performing a dry heat treatment at 160 ° C. for 30 minutes in an oven and measuring the fiber length before and after the heat treatment with a load of 50 g.
Dry heat shrinkage (%) = (Lb−La) / Lb × 100
However, Lb is the fiber length before heat treatment, and La is the fiber length after heat treatment.
* 2: Index display with the conventional example as 100 at the heat set zone and normalizing zone processing temperatures. The higher the value, the higher the temperature.
* 3: Index display with the conventional example set to 100 for the processing tension in the heat setting zone and normalizing zone. The larger the value, the higher the tension.

  As can be seen from the evaluation results of the tire performance shown in Tables 1 to 3, the tires of the examples were not affected by the disturbance of the auxiliary belt layer and the steering stability was excellent as compared with the tires of the conventional example and the comparative example. .

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Bead core 5 Carcass 6 Belt 7 Auxiliary belt layer 8 Belt protective layer

Claims (5)

A carcass extending in a toroidal shape between a pair of left and right bead portions is used as a skeleton, and at least one angled belt layer is sequentially disposed on the outer side in the tire radial direction of the carcass and substantially 90 ° with respect to the tire circumferential direction. In a pneumatic tire comprising an auxiliary belt layer,
The cord of the auxiliary belt layer has the following formula (I),
N1 = n1 × √ (0.125 × D1 / ρ) × 10 ⁻³ (I)
(N1 is the number of twists (times / 10 cm), D1 denotes a display decitex number of twist yarn, [rho is the organic fiber specific gravity (g / cm ^3).) Under under twist factor N1 defined by After twisting, the plurality of the lower twisted yarns are aligned and in the opposite direction to the lower twist, the following formula (II),
N2 = n2 × √ (0.125 × D2 / ρ) × 10 ⁻³ (II)
(N2 is the number of upper twists (times / 10 cm), D2 is the total display decitex number, and ρ is the specific gravity (g / cm ³ ) of the organic fiber.) It is made of a twisted yarn, and the lower twist coefficient N1 and the upper twist coefficient N2 are represented by the following formula (III),
0.95 ≦ N2 / N1 ≦ 3.00 (III)
And the upper twist coefficient N2 is the following formula (IV),
0.55 ≦ N2 ≦ 1.10 (IV)
A pneumatic tire characterized by being a cord twisted so as to satisfy   The pneumatic tire according to claim 1, wherein the carcass cord is an organic fiber.   The pneumatic tire according to claim 1 or 2, wherein the total fineness of the cord of the auxiliary belt layer is 1000 to 9000 dtex.   The pneumatic tire according to any one of claims 1 to 3, wherein the cord of the auxiliary belt layer has a dry heat shrinkage rate of 10 to 15%.   The pneumatic tire according to any one of claims 1 to 4, further comprising a belt protective layer that covers both ends of the auxiliary belt layer and is wound in a spiral shape in the tire circumferential direction.

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