JP2000225809A - Pneumatic radial tire for passenger car - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve moving performance and carcass durability by preventing cord protrusion from an inner liner layer. SOLUTION: In a pneumatic radial tire for a passenger car, a buried cord of at least one sheet of carcass ply is made of steel cord, and a rubber layer 8 having a thickness of 0.3 to 2.0 mm is formed at least partially between a carcass 2 and an inner liner layer 7 within a range of plus or minus 5% of a first belt ply length toward a cross direction from a first belt ply end.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire for a passenger car using a steel cord for a carcass, and more particularly to a pneumatic radial tire for a passenger car having both exercise performance and carcass durability.

[0002]

2. Description of the Related Art Generally, in a radial tire for trucks and buses, a steel cord is used as a reinforcing material for a belt and a carcass. In a radial tire for a passenger car,
A steel cord is used for the belt, and a textile cord such as polyester, nylon or rayon having excellent fatigue resistance is used for the carcass.

[0003] However, radial tires for passenger cars using a textile cord for the carcass have insufficient resistance to trauma, which is likely to occur when the tire side portion comes into contact with a curb, and poor adhesion between the cord and rubber tends to occur. This may lead to cord breakage or separation. Further, the textile cord generally has a low bending rigidity, and it is difficult to increase the rigidity of the side portion of the tire.

[0004] Therefore, it has been proposed to apply a steel cord instead of a textile cord to a carcass of a radial tire for a passenger car.
No. 0803 proposes to use, as a carcass, a steel cord having a 1 + n structure including one core filament and n sheath filaments arranged around the core filament. As a result, the disadvantage described above has been resolved.

[0005]

However, since the steel cord is hardly stretched, there is a problem that the steel cord of the carcass ply projects from the inner liner layer, that is, the so-called inner liner layer cord is easily exposed. As a countermeasure against such a problem, the improvement of the steel cord, that is, the high elongation, is an improvement based on the fact that the entire cord is uniformly stretched. I was

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pneumatic radial tire for a passenger car, which improves the athletic performance and also improves the carcass durability by preventing the inner liner layer cord from coming out.

[0007]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have adopted a steel cord for a carcass ply and, at the same time, provided a specific rubber layer at a predetermined position adjacent to the carcass. As a result, the present inventors have found that the above object can be achieved, and have completed the present invention.

That is, a pneumatic radial tire for a passenger car according to the present invention comprises a carcass comprising at least one carcass ply folded back by a pair of bead cores and connected in a toroidal shape; At least one pneumatic radial tire for a passenger car, comprising a belt made of at least one steel cord belt ply disposed between a tread and the carcass, and a pair of sidewalls disposed on the left and right sides of the tread. The embedded cord of the carcass ply is made of steel cord, and a thickness (gauge) of 0.3 to 2.0 mm is provided between the carcass and the inner liner layer.
Characterized in that at least a part of the rubber layer having the following structure is present outside or inside the tire width direction from the end of the first belt ply within a range of 5% of the length of the first belt ply.

In the pneumatic radial tire for a passenger car according to the present invention, the steel cord is 1 × N or 1 + N.
It is preferable to have an N, 2 + N (2 ≦ N ≦ 7) twist structure, and the filament has a wire diameter of 0.125 to
Preferably, it is within the range of 0.25 mm.

The rubber layer has a 50% tensile stress of 3.
The elongation at break of the steel cord embedded in the carcass ply is preferably 3.5% or more.

[0011]

Embodiments of the present invention will be described below. FIG. 1 shows a cross section of a pneumatic radial tire 1 for a passenger car according to an embodiment of the present invention. In the illustrated example, the carcass 2 is composed of a single ply arranged in a direction substantially perpendicular to the equatorial plane, and both ends of the ply are wound around the bead ring 5 to form a winding end and the bead ring 5 A hard rubber bead filler 6 is tapered between the carcass 2 and the ply winding end. The belt 4 includes two belt cords (a first belt ply 4a and a second belt ply 4) in which the belt cords are arranged inclined with respect to the equatorial plane between the carcass 2 and the tread 3.
b) are overlapped so that the codes cross each other.

In the present invention, in order to prevent the inner liner layer cord from coming out and to improve carcass durability, FIG.
As shown in FIG. 2, the distance between the carcass 2 and the inner liner layer 7 is 0.3 to 2.0 mm, preferably 0.5 to 1.5 m.
There is a rubber layer 8 having a thickness of m. This rubber layer 8 is arranged at least partially within a range of ± 5% of the length of the first belt ply in the tire width direction from the end of the first belt ply. As a result, the inner liner layer cord can be locally prevented. Rubber layer 8
If the thickness is less than 0.3 mm, the effect of preventing the cord from coming out is not sufficient, while if it exceeds 2.0 mm, the effect is saturated and the disadvantageous surface due to an increase in weight increases. In order to effectively prevent the inner liner layer cord from coming out, the rubber layer 8
Is preferably 20 mm or more. More preferably, it is 25 to 50 mm.

The rubber component used in the rubber layer 8 used in the present invention is not particularly limited. For example, natural rubber (N
R), butadiene rubber (BR), styrene-butadiene rubber (SBR), and isoprene rubber (IR). Of these, natural rubber and butadiene rubber are preferable.
In addition, compounding agents usually used in the rubber industry, for example, a reinforcing agent such as carbon black, a vulcanizing agent, a vulcanizing aid, a vulcanization accelerator, an antioxidant, a softening agent, and the like can be appropriately provided. Of course it is. By adjusting the type and amount of carbon black, the amount of sulfur, the amount of oil, and the like with respect to the rubber, the tensile stress at 50% elongation is 3.0 MPa.
A rubber layer made of a rubber having a of not more than a is obtained. If the tensile stress of the rubber layer exceeds 3.0 MPa, the difference in elastic modulus between the carcass ply-covered rubber and the inner liner layer becomes large, causing a failure such as separation of the end of the carcass ply during normal running.

[0014] The embedded steel cord of at least one carcass ply used in the present invention preferably has a breaking elongation of 3.5% when measured after being taken out of the tire.
Above, more preferably 4.0% or more. If the elongation is less than 3.5%, the steel cord itself is not preferable in terms of fatigue durability. A cord having a high breaking elongation can be obtained by increasing the amount of molding with respect to the filament pitch length of the cord.

In the present invention, the ply burying cord of the carcass 2 is made of a steel cord, and preferably, the steel cord is 1 × N or 1 + N, 2 + N (2
≦ N ≦ 7) having a single twist or layer twist structure. N
Is preferably a natural number of 3 to 6. When N exceeds 7, the arrangement of the filaments is liable to collapse, and as a result,
It is not preferable in that the permeability of the matrix rubber into the steel cord is reduced, the uniformity as a cord is deteriorated, and a high elongation at break becomes difficult to obtain. The filament diameter of the filament is preferably 0.125 to 0.2.
It is within the range of 5 mm. If the wire diameter is less than 0.125 mm, the wire is hardly drawn during production and the tensile strength is hardly produced, so that the cord strength is reduced, and as a result, the strength of the tire case member is reduced. Exceeding this is not preferred because fatigue resistance deteriorates.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. Various types of pneumatic radial tires for passenger cars were manufactured by using tires having a size of 195/65 R14 and a rim size of 6J × 14 and employing the conditions shown in Table 1 below as a carcass structure and a rubber layer structure. The following evaluation was performed about the obtained test tire.

Driving stability The test tire was placed on a drum having an outer diameter of 3000 mm, and after a load of 400 kg was applied to the tire, the tire was 30 km / h.
After preliminarily running at a speed of 30 minutes, the load was removed and the internal pressure was readjusted to ² kgf / cm ^2, and then, again under the same speed and the same load conditions, the slip angle on the drum was increased up to ± 4 °. Positive and negative were added consecutively.
Next, the cornering force (CF) at each positive and negative angle
Is measured, and the following equation is obtained: CP (kg / degree) = ｛CF (1 °) (kg) + CF (2
°) (kg) / 2 + CF (3 °) (kg) / 3 + CF
The cornering power (CP) was determined at (4 °) (kg) / 4 ° / 4. The evaluation results were indicated by an index when the CP of each test tire was set to 100 for the CP of the control tire (Comparative Example 1). The larger the index, the better the steering stability.

Inspection of inner liner layer code Each of the test tires is filled with air so that the internal pressure becomes 2 kgf / cm ² , and the speed is 60 km / min under a JIS 100% load.
After traveling on a general road up to 20,000 km at h, the presence or absence of an inner liner layer cord was examined.

[0019]

[Table 1] * 1 The tire maximum width section from the end of the first belt ply (Fig. 1
Medium A) has a width of 30 mm.

[0020]

As described above, in the pneumatic radial tire for a passenger car according to the present invention, the steel cord is used for the carcass ply, and at the same time, the specific rubber layer is provided at a predetermined position between the carcass and the inner liner layer. By the presence of the, exercise performance is improved and at the same time, it is possible to locally prevent the inner liner layer cord from coming out,
Carcass durability can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a pneumatic tire for a passenger car according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Carcass 3 Tread 4 Belt 4a 1st belt ply 4b 2nd belt ply 5 Bead ring 6 Bead filler 7 Inner liner layer 8 Rubber layer

Claims (5)

[Claims] 1. A carcass comprising at least one carcass ply folded back by a pair of bead cores and connected in a toroidal shape, a tread arranged on a crown portion of the carcass, and arranged between the tread and the carcass. In a pneumatic radial tire for a passenger car, comprising a belt made of at least one steel cord belt ply and a pair of sidewalls arranged on the left and right sides of the tread, at least one embedment code of the carcass ply is a steel cord. And a rubber layer having a thickness of 0.3 to 2.0 mm between the carcass and the inner liner layer,
A pneumatic radial tire for a passenger car, which is at least partially present within a range of ± 5% of a belt ply length. 2. The steel cord is 1 × N or 1+
2. A twisted structure of N, 2 + N (2 ≦ N ≦ 7).
The pneumatic radial tire for a passenger car as described. 3. The steel cord according to claim 1, wherein a filament diameter of the filament is in a range of 0.125 to 0.25 mm.
Or the pneumatic radial tire for a passenger car according to 2. 4. The rubber layer has a 50% tensile stress of 3.0 M.
The pneumatic radial tire for a passenger car according to any one of claims 1 to 3, which is not more than Pa. 5. The pneumatic radial tire for a passenger car according to claim 1, wherein an embedded steel cord of the carcass ply has a breaking elongation of 3.5% or more.