JPH01109105A - Pneumatic radial tire for heavy load - Google Patents

Abstract

PURPOSE:To improve durability at the above tire arranged with at least more than 2 carcass plies by using as a carcass material vinylon which has a high elasticity modulus and a high strength and has undergone a predetermined heat treatment. CONSTITUTION:An arrangement is so made that vinylon whose molecular weight has drastically increased in comparison with that of a prior vinylon and which has a high elasticity modulus and a high strength is used as a carcass material, and this vinylon is manufactured by a method in which polymer of a super high molecular weight is used and a centrifugal magnification at the time of yarn making is heightened. And vinylon such as this is heat-treated by means of a treatment liquid using a soft resin of pre-contraction type in order to increase the anti-fatique quality of vinylon, and then, the number of driven in pieces per 5cm in the direction of the width of cord members shaped like a reed screen after rubberization is set at 30-60 pieces and a carcass ply is to be manufactured.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a heavy-duty pneumatic radial tire, and more specifically to a heavy-duty pneumatic radial tire that uses a specific carcass cord to significantly improve the appearance quality and durability of the tire. It relates to pneumatic radial tires.

[Conventional technology]

Traditionally, materials such as steel, aramid, nylon, polyester, and rayon have generally been used as carcass cord materials for radial tires, but they are particularly important for so-called heavy-duty pneumatic radial tires, which have relatively high internal pressure and high loads. Steel, aramid and polyester are used. The reason for this is that at high internal pressures and high loads, it is preferable to reduce the elongation of the carcass cord material and suppress distortion at the belt end or carcass end of the radial tire as much as possible.

[Problem that the invention seeks to solve]

Recently, there has been an increasing need for this type of pneumatic radial tire for heavy loads to be able to travel at high speeds, under heavy loads, and over long distances, and highly durable tires are desired. Furthermore, appearance quality is also becoming more important. However, a tire that satisfies all of these requirements has not yet been provided. This is because the conventional carcass materials mentioned above do not provide a cord that satisfies all aspects such as strength, creep, heat shrinkage, and fatigue resistance, and each material has its own problems. Nothing but. For example, steel has low creep and low elongation, but it is heavy and corrodes, while aramid, on the other hand, is light, has low creep and is strong, but has poor compression fatigue resistance. Polyester is light but has a high heat shrinkage rate, resulting in poor uniformity, while rayon has a low heat shrinkage rate but low strength. Nylon has high strength but has a large amount of creep.

[Means for solving problems]

Therefore, in order to solve the above problems, this invention has a low dry heat shrinkage rate and low creep like aramid and rayon.
As a result of extensive research into carcass materials that have higher strength than polyester and nylon, we have achieved high durability by using vinylon, which has a high elastic modulus and high strength and has a significantly increased molecular weight than conventional vinylon, as a carcass material. The present inventors have discovered that a heavy-duty pneumatic radial tire with good appearance quality can be obtained, and have completed the present invention.

In other words, this invention provides a heavy-duty pneumatic radial tire with at least two or more carcass plies, and uses a high-strength material that has a strength greater than that of conventional nylon and an elastic modulus almost twice that of conventional polyester as a reinforcing material for the carcass ply. Vinylon, which has high strength and high elastic modulus, was used. This vinylon is obtained by using an ultra-high molecular weight polymer and increasing the draw ratio during spinning.

However, in order to apply this invention to a pneumatic radial tire for heavy loads, from the viewpoint of improving the tire safety factor, appearance quality, and durability, it is necessary to increase the number of cords of this type per 5 cm in the width direction of the rubberized blind. Limited to 30 to 60 pieces.

This is because if the number of cords is less than 30, the cords will be inserted sparsely and unevenness on the side will become noticeable, which is not desirable in practical terms. Cord construction 1500d/2 requires 5 plies, cord construction 1500d/3 requires 4 plies.
This is because plying is required, which increases the thickness of the carcass layer, resulting in increased heat generation and increased weight during tire running, which is rather undesirable. On the other hand, the number of strokes is limited to 60, but this is because a thick denier cord structure such as 1500 d/3 will not produce uniform blinds, and a cord structure of 1500 d/2 will have a small cord space. This is because separation occurs while the tire is running, causing problems such as reduced durability.

Additionally, the present invention is characterized in that the cord is heat treated with a treatment liquid of a softening adhesive using a flexible resin of the former type. This has a high elastic modulus,
This is to roughly improve the fatigue resistance of vinylon, which has high strength. In other words, a general resorcinol-formalin-latex (RFL) treatment solution does not provide sufficient durability for reinforcing materials of this type, but if treated with a treatment solution that uses a softening adhesive, the cord hardness can be reduced. By reducing this, tire durability can be greatly improved.

[Effect]

Since this invention has such a structure, the carcass reinforcement material has strength, excellent modulus of elasticity, low creep, excellent compression fatigue resistance, low cord hardness, and no increase in heat generation or weight, resulting in improved durability and appearance quality. It can be made into a heavy-duty pneumatic radial tire that exhibits particularly remarkable effects.

〔Example〕

Examples 1 to 4, Comparative Examples 1 to 5 In both Examples and Comparative Examples, after applying the following ordinary RFL treatment solution (B) or treatment solution using softening adhesive (A>) to the carcass ply cord, cord to about 200℃
The fabric was heat-treated at a temperature of about 2% with a stretch of about 2%, and then made into a rubberized cloth as usual, and then molded and vulcanized to obtain each test tire. The following performance evaluation tests were conducted on the obtained test tires. Note that Examples 1 to 4
In Comparative Examples 1 to 5, 11R22,516PR radial tires were used. Further, the material, adhesive, structure, number of plies, number of cords, and cord hardness of the carcass ply cords of each radial tire in the above Examples and Comparative Examples are as shown in Table 1 below.

1. Cord Hardness A cord is passed over two intersection points with both ends free, and the resistance force when the center part of the cord is pressed and bent is calculated using polyester (Comparative Example 4).
) is expressed as an index value as 100.

2. Weight Steel Tire (Comparative Example 5) The weight of the tire is set as 100 and is expressed as an index value.

3. Rotate the tire filled with side unevenness internal pressure 7.0 kg/Cm2,
The difference between the maximum and minimum values of the concave part of the tire side part is continuously detected in an angular range of 5 degrees in the tire circumferential direction using a strain meter, and the size of the difference is indicated in 10 grades. Displayed as a class.

4. Uniformity The tire is rotated with the air pressure and load specified in JIS D-4202, and the magnitude of the force variation in the radial direction of the tire is indicated by grade, with grade 5 indicating the best.

5. Durability Evaluated in accordance with FMVSSl 19 and expressed as an index with steel ply tire durability as 100.

6° rolling resistance 5Evaluated in accordance with AEJ1379, with steel ply tires set as 100 and expressed as an index.

The results of each of the above tests are also listed in Table 1.

(Leaving space below) Processing liquid A: Pre-condensation type flexible resin Processing liquid B Niresorcin-formalin-latex processing liquid Processing liquid composition table *Penacolite R2170 manufactured by Koppaz Co., Ltd. Sumika Lure 00 manufactured by Sumitomo Chemical Co., Ltd. It is clear from Table 1 above Similarly, Comparative Example 1 is a tire having the same structure as Example 2, but because the treatment liquid is RFL, the cord is hard and the tire durability is low. Comparative Example 2 has the same number of plies as Example 1, but the number of cords is more. Comparative Example 3 has the same cord structure as Example 2.3.4, but the number of cords is less, so the number of plies is larger ( (to ensure safety factor), tire durability decreased. On the other hand, it is recognized that the durability of the examples is extremely high.

〔Effect of the invention〕

As described above, the present invention provides a heavy-duty pneumatic radial tire with a carcass ply of at least two braises, in which the reinforcing material of the carcass ply is made of vinylon having a high elastic modulus and high strength, and is made of pre-condensation type flexible resin. The number of strokes per 5 cm in the width direction of the blind after rubberization is 30 to 30.
Since the configuration has 60 tires, it was possible to provide a heavy-duty pneumatic tire with excellent appearance quality and high durability.

Claims (1)

[Claims] (1) In a heavy-duty pneumatic radial tire with at least two or more carcass plies, the reinforcing material of the carcass ply is made of vinylon, which has a high elastic modulus and high strength, and is treated using a pre-condensation type flexible resin. 1. A pneumatic radial tire for heavy loads, characterized in that the pneumatic radial tire is heat treated with a liquid and the number of tires per 5 cm in the width direction of the blind after rubberizing is 30 to 60.