JPH03287402A - Radial tire - Google Patents

Abstract

PURPOSE:To obtain a radial tire excellent in high speed durability by using a polytetramethylene adipamide cord, provided with the specific elongation percentage under a constant load and dry heat contraction coefficient, for a belt reinforcing layer. CONSTITUTION:A radial tire 7 for a passenger car or the like is formed of a tread part 1, a side wall part 2, a bead part 3, a carcass part 4, a belt layer 5, and a belt reinforcing layer 6. That is, the belt reinforcing layer 6, formed of a heat contractive cord, is provided on the outer peripheral side of the belt layer 5. In this case, the polytetramethylene adipamide cord, in which the elongation percentage E under a constant load is 7.5-10.4% and the dry heat contraction coefficient H is less than 2.0%, is used for the belt reinforcing layer 6. The radial tire of fine uniformity and excellent high speed durability can be thereby obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention provides a radial tire with excellent high-speed durability.

<Prior Art> A radial tire 7 for a passenger car, etc., is composed of a trend part 1, a sidewall part 2, a bead part 3, a carcass part 4, a belt layer 5, and a belt reinforcing layer 6, as shown in FIG. ing.

That is, on the outer peripheral side of the belt layer 5, a belt reinforcing layer 6 made of a heat-shrinkable cord is provided. This belt reinforcing layer 6 has the effect of suppressing the rise of the belt layer 5 due to centrifugal force during high-speed running, and is extremely important in improving the high-speed durability of the radial tire 7.

When manufacturing the radial tire 7, the belt reinforcing layer 6 is wrapped around the outer circumferential side of the belt layer 5, and the belt reinforcing layer 6 is wrapped around the outer circumferential side of the belt layer 5 so that a predetermined overlapping portion 8 is formed as shown in FIGS. Both ends, that is, the winding start part 6a and the winding end part 6b are overlapped. However, since a heat-shrinkable cord is used when vulcanizing by pressure and heating, the belt reinforcing layer 6 shrinks and becomes misaligned, resulting in a sufficient overlapping area as shown in Figure 3 when unvulcanized. 8, the overlapping portion 8 becomes smaller after vulcanization as shown in FIG. Therefore, if this amount of deviation becomes large, the belt layer 5 will be deformed at the overlapping portion 8 of the belt complements 9!116, resulting in poor tire uniformity and reduced high-speed durability.

Therefore, in order to prevent this, Japanese Patent Laid-Open No. 61-1138
As disclosed in Japanese Patent No. 52, it has been proposed to use nylon 4.6 fiber.

(Problem B to be solved by the invention) However, as the cord of the belt reinforcing layer 6, it is simply made of nylon 4.
．． If only 6-series fibers are used, the problem caused by heat shrinkage during vulcanization cannot be sufficiently solved, and a radial tire with excellent high-speed durability cannot be manufactured.

In view of such conventional problems, an object of the present invention is to provide a radial tire having better high-speed durability.

(Means for Solving the Problems) The present invention provides a radial tire in which a bell-top reinforcing layer 6 is provided on the outer peripheral side of a belt layer 5.
．． 4%, a polytetramethylene diramine cord having a dry heat shrinkage rate H of less than 2.0% is used.

(Function) The belt reinforcing layer 6 has a constant load elongation E of 7.5 to 10.
．． To obtain a radial tire with good uniformity and excellent high-speed durability by using a cord made from polytetramethylene diramine processed in 0916 so that the dry heat shrinkage rate H is less than 2.0%. I can do it.

In this case, the elongation rate E at constant load is JIS L-10
17 (standard time test), and the dry heat shrinkage rate H
was measured according to JIS L-1017 (standard time test) (measurement conditions: 160° C. for 30 minutes, Method B).

The reason why the elongation rate E under constant load was set to 7.5 to 10.0 was 7.
．． If it is less than 5%, when an unvulcanized tire with an outer diameter smaller than the mold is inflated to the same outer diameter as the mold during tire vulcanization, the unvulcanized tire will deform in the circumferential direction, resulting in a tire with good uniformity. This is so that you will not be affected. Furthermore, if the elongation rate E at constant load exceeds 10.0%, the belt reinforcement effect that suppresses the rise of the belt 115 during high-speed running cannot be obtained, and high-speed durability decreases.

When the dry heat shrinkage rate is 2.0% or more, when the unvulcanized tire is vulcanized by pressure heating, the displacement of the overlapping portion 8 of the belt reinforcing layer 6 becomes large, causing deformation of the belt layer 5. , the uniformity will deteriorate and high-speed durability will not be improved.

(Example) Examples of the present invention will be described below.

In the radial tire 7 of tire size T/L 185/70 R14, the belt reinforcing layer 6 is made of nylon 4.
6 type fiber, i.e. polytetramethylene adivamodo fiber 84
A cord with adhesive treatment applied to 0 D/2 (48 first twists/Loan, 48 final twists, 710 value) was used. Note that the number of belt reinforcements N6 is one, and the number of cords inserted is 25.0 cords/inch.

In Example 1, a cord with a constant load elongation E of 7.5% and a dry heat shrinkage H of 1.8% was used;
Then, the elongation rate E under constant load is 8.5% and the dry heat shrinkage rate H is 1.
．． Three types of radial tires 7 were manufactured using a 2% cord and, in the example, a cord having an elongation E under constant load of 10.0% and a dry heat shrinkage H of 0.5%.

On the other hand, as Comparative Example 1, a cord with a dry heat shrinkage rate H of 4.0% was used at a constant load elongation E of 7°0), and as a Comparative Example 2, a constant load elongation E of 11.0 was used. % and a dry heat shrinkage rate H of 0.2%.As Comparative Example 3, a nylon 66 fiber with an elongation rate at constant load of 8.0% and a dry heat shrinkage rate H of 6.0% was used. Three types of radial tires 7 for use with cords were manufactured.

When the uniformity and high-speed durability (JIS and ECE $130) of these radial tires 8 were measured and compared, the results shown in the following table were obtained.

In addition, uniformity is measured by air pressure-load based on JIS D-4202, and high-speed durability is measured according to JIS D-4230, and ECE cloud 30. If so, then ■. Uniformity and high-speed durability were 10% compared to Comparative Example 3.
It is expressed as an index value with 0 as the value, and the smaller the value of the former, the better the value, and the larger the value of the latter, the better the value.

As is clear from this result, Examples 1 to 3 of the present invention
In the case of , it can be seen that the uniformity of the bay is better than that of Comparative Examples 1 to 3, and the high-speed durability is excellent.

By the way, the - of nylon 4.6 fiber (840D/2)
The constant load elongation E and the dry heat shrinkage H have a relationship as shown in FIG. Therefore, taking this into consideration, the elongation rate E under constant load is 7.5 to 10.4%, and the dry heat shrinkage rate H is 2.0%.
The conditions may be determined so that it is less than %.

(Effects of the Invention) According to the present invention, the belt reinforcing layer 6 is made of polytetramethylene having an elongation E under constant load of 7.5 to 10.4% and a dry heat shrinkage H of less than 2.0%. Since it uses Giramine cord, it is possible to obtain a radial tire with extremely superior high-speed durability compared to conventional tires.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a radial tire, Figure 2 is a perspective view of the same,
3 and 4 are explanatory diagrams, and FIG. 5 is a diagram showing the relationship between the elongation rate E under constant load and the dry heat shrinkage rate H. 5... Belt layer, 6... Belt reinforcement layer, 8... Overlapping portion. Patent applicant Otsu Tire Co., Ltd. Figure 1 113eii 1 114 Figure 2 1

Claims (1)

[Claims] (1) In a radial tire in which a belt reinforcing layer (6) is provided on the outer circumferential side of the belt layer (5), the belt reinforcing layer (6) has an elongation rate (E) under a constant load of 7.
A radial tire characterized by using a polytetramethylene diramine cord having a dry heat shrinkage rate (H) of 5 to 10.4% and less than 2.0%.