JPH019682Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Technical Field of the Invention] The present invention relates to a pneumatic radial tire, and more specifically, by covering the tread portion of the tire with an outer skin that has excellent oxygen barrier properties and is easily worn,
A pneumatic radial tire with excellent durability that does not cause aging of the tread even in high-temperature atmospheres such as shipping, and whose outer skin quickly wears out during use so that it can touch the ground at its original tread. It is. [Prior Art] In order to improve the maneuverability, ride comfort, rolling resistance, or performance on ice and snow of a vehicle, improvements have been made to the structure and rubber materials of tires. For example, JP-A-55-135149 describes that the hardness of tread rubber has a great effect on performance on ice and snow. Additionally, steel radial tires may be blended with large amounts of extender oil or plasticizers to improve ride comfort, and spikeless tires or snow tires may be blended with large amounts of butadiene rubber to improve performance on ice and snow. It is being done.
However, tires are often left on the bottom of a high-temperature ship for a long period of time, and seasonal spikeless tires may be left in a warehouse for up to a year, causing the tread rubber to deteriorate in the high-temperature atmosphere.
The problem was that the hardness and modulus changed, making it impossible to achieve the desired performance. In order to improve such drawbacks, for example, JP-A-58-87138 and JP-A-58-139803 disclose that various anti-aging agents are added to tread rubber. Adding a large amount of the agent itself does not have a very positive effect on the performance of the rubber, so it cannot be used in large quantities, and as a result, changes in rubber hardness due to aging are inevitable in long-term high-temperature atmospheres. It was the actual situation. [Purpose of the invention] The purpose of the invention is to solve the above-mentioned conventional problems, and to prevent deterioration even when exposed to high temperature atmosphere for a long time.
Another object of the present invention is to provide a pneumatic radial tire that can use a tread portion having the desired performance during running. [Structure of the invention] The structure of the invention includes a pair of left and right beat parts, a pair of left and right sidewall parts connected to the beat parts,
It consists of a tread part located between the sidewall parts, and a carcass layer having a cord angle of substantially 90 degrees with respect to the tire circumferential direction is mounted between the pair of left and right beat parts, and a carcass layer on the carcass layer in the tread part is installed. , the cord angle with respect to the tire circumferential direction is
In a radial tire comprising a plurality of belt layers that intersect with each other at an angle of 10° to 30°, the contact surface side of the tread portion has a thickness of 20% or less of the depth of the main groove of the tread portion, and is provided with ventilation. The gist of the tire is a pneumatic radial tire provided with a vulcanized and integrated skin rubber whose air permeability and abrasion resistance are lower than those of treaded rubber. Hereinafter, the configuration of the present invention will be explained in more detail.
The structure of the tire according to the present invention can be the same as that of a known radial tire, except that the tread portion is provided with an outer skin. The thickness of the outer skin provided on the contact surface side of the tread portion must be 20% or less of the depth of the main groove of the tread portion. This outer skin blocks oxygen from the atmosphere and serves to prevent the tread rubber from aging, but it must quickly wear out or peel off when the tire is used. Therefore, if it is thick enough to exceed 20% of the tread groove, the wear life of the tire will be shortened and the intended purpose cannot be achieved, and if it is too thin, there will be problems with air permeability. Therefore, preferably 5-15%
is within the range of It is necessary that the permeability and abrasion resistance of the outer skin be lower than those of the treaded rubber. In other words, the lower the air permeability and the better the oxygen barrier properties, the higher the anti-aging properties of the treaded rubber. Similar to the aforementioned thickness, the wear resistance is better as it is lower because the outer skin needs to be quickly worn away when the tire is in use. Preferably, the breathability and abrasion resistance of the outer skin are 50% or less of those of treaded rubber. The material of the outer skin is not particularly limited, but since it covers the tread rubber, vulcanizable rubber is preferred. In addition, the material, performance, physical properties, etc. of the treaded rubber should be selected depending on the various uses, but the effectiveness of the present invention is significant when the permeability of the rubber is 20ml・cm/cm ²・sec・Hg or more. . Methods for providing the outer skin on the contact surface side of the tread rubber include pasting the outer skin on the tread portion in advance during the extrusion process before molding, extruding the opposed tube tube outer skin and the tread rubber as one body, or treading the outer skin during molding. It is possible to adopt a method such as pasting it on the parts. The outer skin bonded to the tread portion in this manner becomes an integrated outer skin rubber by being vulcanized during vulcanization molding of the tire. Hereinafter, the structure of the present invention will be explained with reference to the drawings. FIG. 1 is an explanatory cross-sectional view of the pneumatic radial tire of the present invention, and the bead portion has a bead wire 1.
There are sidewalls 2 on both outer sides, and tread rubber A is provided between both sidewalls. The carcass layer 3 is mounted at a cord angle of substantially 90° with respect to the tire circumferential direction. The belt layers 4 cross each other at cord angles of 10° to 30° with respect to the tire circumferential direction. side wall 2
The boundary between this and the tread rubber A forms a shoulder 5. A groove 6 is provided in the tread rubber A,
An undertread rubber B is arranged below the carcass layer 3, and an inner liner 7 is arranged inside the carcass layer 3. An outer skin S is provided on the contact surface side of the tread rubber A. FIG. 2 is an explanatory cross-sectional view of a main part showing another example of the pneumatic radial tire of the present invention, in which the tread rubber A covers the sidewall 2 and forms the shoulder 5. The outer skin S is provided on the entire tread rubber including the shoulder 5. The effects of the present invention will be explained below with reference to Examples. [Example] Tire size is 165SR13, carcass is 1500d/
The belt layer consists of 1x polyester with a wire diameter of 0.25mm.
Five-structure steel cords were arranged at 20 degrees to the equatorial plane, making it a two-ply structure. The depth of the main groove in the tread part was 7.8 mm, and the thickness of the outer skin was 1 mm. In other words, the thickness of the outer skin is 12.8% of the depth of the main groove. Table 1 shows the compositions of the two types of tread rubber, outer skin rubber, and side rubber that were produced.

[Table] Next, these rubbers were vulcanized at 160℃ for 15 minutes,
Air permeability measured by ASTMD1434-75
Table 2 shows the physical properties measured according to JISK6301.

[Table] The structure of the manufactured tire is shown in Table 3 below. For untreated tires and tires left at 70℃ for 7 days, the hardness of the tread surface (outer skin), the hardness of the tread rubber after removing the outer skin (1 mm) by running, and the distance traveled to wear the outer skin (compared to conventional products) index) was measured and shown in Table 3. Note that the larger the value of the mileage index, the less likely it is to wear out.

【table】

[Table] From the results in Table 3, it can be seen that the tire of the present invention does not change in hardness even when the tread rubber is placed in a hot atmosphere, compared to the conventional and comparative products. It also shows that the skin wears off quickly. Therefore, the tire of the present invention prevents aging due to a hot atmosphere, and when used, the original tread rubber quickly appears on the surface, and the outer skin does not adversely affect running.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional explanatory view of a pneumatic radial tire according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional explanatory view of essential parts of a pneumatic radial tire according to a second embodiment of the present invention. 1...Bead wire, 2...Side wall, 3
...carcass layer, 4...belt layer, 5...shoulder,
6...Main groove, 7...Inner liner, A...Tread rubber, B...Under rubber, S...Outer skin.

Claims (1)

[Scope of utility model registration request] Consisting of a pair of left and right bead parts, a pair of left and right sidewall parts connected to the bead parts, and a tread part located between the sidewall parts, the cord angle between the pair of left and right bead parts with respect to the tire circumferential direction is substantially The carcass layer is mounted at an angle of 90°,
Further, in a radial tire in which a plurality of belt layers intersecting each other at a cord angle of 10° to 30° with respect to the tire circumferential direction are arranged on a carcass layer in the tread portion, on the ground contact side of the tread portion,
The provision of a vulcanized, integrated outer skin rubber whose thickness is 20% or less of the depth of the main groove of the treaded portion, and whose air permeability and abrasion resistance are lower than those of the tread rubber. Features pneumatic radial tires.