JP2003063207A - Pneumatic tire for emergency - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire for emergency capable of suppressing generation of an ozone crack without causing an increase in weight and lowering of manufacturing workability. SOLUTION: By setting surface roughness of a side part 26 of this pneumatic tire for emergency 10 to 35 to 560 μm rougher than that of a side part of a conventional tire, surface area can be increased as compared with the side part of the conventional tire. Therefore, surface distortion of the side part 26 is reduced to suppress generation of the ozone crack.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an emergency pneumatic tire, which is called a T type in the standards such as JATMA, ETRTO, and TRA, and which has a high internal pressure and a narrow width.

[0002]

2. Description of the Related Art In recent years, passenger cars have been reduced in cost and weight,
For the purpose of reducing the volume during storage, a narrow-width type pneumatic tire called T-type emergency tire, which has a high internal pressure and uses high pressure air, is installed.

[0003] Conventionally, the main storage location of the emergency pneumatic tires has been in the trunk, but in recent years the number has increased to 1B.
OX cars have adopted a method of suspending the emergency pneumatic tires under the floor in order to secure a trunk space.

On the other hand, due to the improvement of the road surface environment, the chances of occurrence of puncture are decreasing, and in this case, the emergency pneumatic tire remains stored for a long time in an unused condition.

[0005]

By the way, when storing under the floor, the tires are always exposed to the atmosphere, and compared with the case where the tires are stored in the trunk, ozone in the atmosphere, heat during running, rainwater, etc. The ozone crack is likely to occur in the side portion of the emergency pneumatic tire.

As a prescription for this, it has been customary to change the rubber composition (for example, to increase the amount of wax and an antioxidant), but this method raises the cost and increases the ply and tread during tire molding. There is a problem such as a decrease in manufacturing workability due to a decrease in adhesion.

As another method, there is a method of reducing surface strain, which generally increases the tread gauge,
In this case, there is a problem that the tire mass increases and the weight reduction, which is a feature of the emergency pneumatic tire, is impaired.

In consideration of the above facts, an object of the present invention is to provide an emergency pneumatic tire capable of suppressing the generation of ozone cracks without causing an increase in weight and a decrease in manufacturing workability. .

[0009]

The invention according to claim 1 is used in place of a standard installation tire of an automobile, the tire width is extremely narrow with respect to the standard installation tire, and the tire outer diameter is substantially the same. And a high-use pneumatic tire for emergency use, characterized in that the surface roughness of the side portion is set to 35 μm or more.

Next, the operation of the pneumatic tire according to claim 1 will be described.

The surface roughness of the workpiece is, for example, JIS B
Although it was established in 0601, the surface finish of the mold that molds the current emergency pneumatic tires is the same as that of general tires, with precision finishing (JIS finish symbol ▽▽▽.
1.5 to 6 μm) is applied, and the surface roughness of the emergency pneumatic tire molded by the mold is similar to that of the mold surface.

In the pneumatic tire for emergency use according to the first aspect, since the surface roughness of the side portion is set to 35 μm or more (∇ in the JIS finish symbol), the surface area can be increased as compared with the conventional case. Therefore, the surface strain is reduced and the generation of ozone cracks can be suppressed.

The invention according to claim 2 is characterized in that, in the emergency pneumatic tire according to claim 1, the surface roughness of the side portion is set to 560 μm or less.

Next, the operation of the pneumatic tire according to claim 2 will be described.

If the surface roughness of the side portion exceeds 560 μm, the appearance of the emergency tire may be deteriorated and the commercial value thereof may be impaired.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a pneumatic tire for emergency use according to the present invention will be described with reference to the drawings.

As shown in FIG. 1, an emergency pneumatic tire 10 of this embodiment has a bias structure including a pair of bead cores 12 and a carcass 14 straddling the toroidal shape between the pair of bead cores 12. It is a tire containing.

A squeegee rubber 16 and an inner liner 18 are sequentially arranged on the inner peripheral surface side of the carcass 14,
The tread rubber 2 forming the tread portion 20 on the outer peripheral surface side
2 are arranged, and side rubbers 28 that constitute the side portion 26 are arranged on both side surfaces of the bead portion 24.

The carcass 14 is a single carcass ply 30.
The carcass ply 30 has the bead core 12 folded back from the inside of the tire to the outside, and the folded-back portion 30A is
It is arranged along the main body 30B and extends outward in the tire radial direction so as to extend over the tread end portion 20A and not over the other tread end portion 20A.

The carcass ply 30 has a known structure in which a large number of ply cords arranged in parallel with each other are coated with rubber.

The carcass 14 has its tread portion 20 overlapped at both widthwise end portions.

The surface roughness of the side portion 26 is 35 as a whole.
It is set to ˜560 μm (∇ in JIS finish code).

Here, the side portion 26 means the rim line 3
The area from 2 to the tread edge portion 20A. When the position of the tread end 20A is not clear, the position at a height of 90% of the tire cross-section height H (the position of 0.9H in the figure) is set as the tread end.

Next, the operation of the emergency pneumatic tire 10 of this embodiment will be described.

In the emergency pneumatic tire 10 of this embodiment, the surface roughness of the side portion 26 is 35 to 5 which is rougher than the conventional one.
Since the thickness is set to 60 μm, the surface area can be made larger than that of the side portion of the conventional tire.

Therefore, the surface strain of the side portion 26 is reduced, and the generation of ozone cracks is suppressed.

The surface roughness of the side portion 26 is 560.
If the thickness exceeds μm, the outer appearance is deteriorated, so that the commercial value of the emergency tire may be impaired. (Test Example) In order to confirm the effect of the present invention, an emergency pneumatic tire of the example to which the present invention was applied and a conventional emergency pneumatic tire were prepared and an ozone crack evaluation test was conducted.

The emergency pneumatic tire used in the test had a size of T125 / 70D16 and was 16 × 4T.
It was attached to the rim of and was filled with an internal pressure of 420 kPa.

The surface roughness of the side portion of the emergency pneumatic tire of the example is 200 μm, and the surface roughness of the side portion of the conventional pneumatic tire for emergency is 3 μm.

The test condition is that the ozone concentration is about 20 in the natural environment.
The sample was left in a room (temperature 40 ° C.) set to 0 times, and the period (days) until the occurrence of ozone cracks was examined.

The evaluation was represented by an index with 100 as the number of days when ozone cracks occurred in the tire of the conventional example. The larger the value, the longer the period until ozone cracks occur, and the better the ozone crack performance.

[0032]

[Table 1] As shown in Table 1 above, it is apparent that the tires of the examples to which the present invention is applied are superior in ozone cracking property to conventional tires.

Further, the tire of the example could be manufactured by the same manufacturing process and manufacturing time as the tire of the conventional example, and the manufacturing cost was not changed.

In the mold for molding the tire of the embodiment, the side surface molding surface does not have to be precisely finished, so that the processing cost can be reduced.

[0035]

As described above, since the emergency pneumatic tire of the present invention has the above-mentioned structure, it does not cause an increase in weight and a decrease in manufacturing workability, and suppresses the generation of ozone cracks. It has an excellent effect that

[Brief description of drawings]

FIG. 1 is a sectional view taken along a tire rotation axis of a first-aid pneumatic tire according to an embodiment of the present invention.

[Explanation of symbols]

10 First-aid pneumatic tires 26 Side part

Claims (2)

[Claims] 1. A pneumatic tire for emergency use, which is used in place of a standard-installed tire of an automobile, has a tire width extremely narrower than that of the standard-installed tire, has substantially the same tire outer diameter, and has a high internal pressure. The pneumatic tire for emergency use, wherein the surface roughness of the side portion is set to 35 μm or more. 2. The emergency pneumatic tire according to claim 1, wherein the surface roughness of the side portion is set to 560 μm or less.