JPH0374203A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To remarkably increase durability in high speed running of a vehicle by providing a carcass ply layer, in which organic fiber cords of a core- sheathing structure, arranged parallel with each other, are arranged at a prescribed cord-angle, thereby forming a pneumatic tire. CONSTITUTION:Organic fiber cords are manufactured by intertwining organic fiber base yearns having a core-sheath structure consisting of a core part and a sheath part, which covers a circumference of the core part. A pneumatic tire is formed by providing at least one layer of carcass ply layer, in which the said organic fiber cords are placed parallel with each other, is arranged at a cord angle of 40 deg. to 90 deg. with respect to the equatorial plane of the tire. The said core part is formed with polyurethane naphthalene-2,6-dicarboxylate having a repeating unit as shown in the expression-I, while the sheath part is formed with polyamide. In addition, the core part should be 30 to 90weight% the entire base yarns.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a pneumatic tire, particularly a pneumatic tire in which the durability of the carcass reinforcement material is improved and the high-speed durability is significantly improved. Relating to a pneumatic tire with improved reinforcement and improved high-speed durability.

(Prior art) Traditionally, carcass ply cords for radial tires have been mainly made of steel for large to medium-sized tires, such as tires for trucks, lotuses, and construction vehicles, and polyester has been used for small- to medium-sized tires, such as tires for small trucks and passenger cars. , nylon and rayon are the mainstream. In this case, the reason why steel cord is used for the carcass of large tires is that these tires are generally used under high internal pressure and high load conditions, and the large amount of heat generated by the tires due to this is due to the physical properties of the tires due to heat. This is because a steel cord with the smallest change is suitable. However, steel cords have the disadvantage that they are susceptible to corrosion due to contact with water that has passed through the tire exterior or is sealed inside the tire.

In order to overcome this drawback, attempts have been made to use fully aromatic polyamide (aramid) instead of steel, but there are problems such as insufficient bending fatigue resistance and adhesive strength, and high cost. It has not yet reached the point where it has been generalized as a.

On the other hand, in the case of passenger car tires, nylon has problems such as low elastic modulus, high heat shrinkage, insufficient creep properties, poor flat spot properties, uniformity, and insufficient side unevenness. Also, rayon is
Since it has the lowest strength, it needs to be used in a larger amount than polyester to obtain the same strength as carcass material, and it is also prone to injury due to the presence of moisture, and long-term storage in a humid atmosphere deteriorates the adhesion level and physical properties, especially the strength. There are problems such as a decrease in

On the other hand, polyester is the best of the three without the above-mentioned drawbacks, but it still has major drawbacks such as resistance to amine decomposition and hydrolysis.

This is a phenomenon in which the polyester is decomposed in the carcass by the polyester component contained in the embedded rubber, resulting in a decrease in molecular weight and a concomitant decrease in strength or adhesive force. This naturally accelerates as the tire temperature increases, so there is a problem in applying it to the carcass of large tires.
Problems remain in application due to the increased severity of the carcass due to heat.

Claims (1)

[Scope of Claims] 1. A pneumatic tire comprising at least one carcass ply layer comprising organic fiber cords arranged in parallel to each other at a cord angle of 40 to 90° with respect to the equatorial plane of the tire. The organic fiber cord is a cord made by twisting organic fiber filaments that have a core-sheath structure consisting of a core and a sheath that wraps around the core, and the core has the following formula ▲ Numerical formula, chemical formula, table, etc. It is made of polyethylene naphthalene-2,6-dicarboxylate having the repeating unit shown by ▼, the sheath part is made of polyamide, and the core part is made of three
The organic fiber cord has the following formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, NT is the twist coefficient, T is the number of twists of the cord (twice/10 cm), and ρ is (The specific gravity of the fibers, D indicates the total denier of the cord.) A cord formed by twisting together a first twist and a first twist within a range of 0.3 to 0.6, with a twist coefficient NT expressed as: A pneumatic tire characterized in that the heat shrinkage rate at 177° C. of the dip-treated cord before making the tire is 5.0% or less. 2. 0 of the organic fiber cord taken out from the tire product
．． Elongation E_1 at 6 g/d and elongation E_ at 0.3 g/d
2. The pneumatic tire according to claim 1, wherein the difference ΔE=E_1−E_2 from ΔE=E_1−E_2 is less than 1.0%. 3. In a radial tire reinforced with a radial carcass and a plurality of belt cord (cord A) layers in which the cord arrangement provided at the upper tread position of the carcass alternately intersects, the belt cord (cord A) closest to the tread surface is ) layer and the tread rubber layer, further reinforced at least at the end of the belt cord (cord A) layer by one or more cord (cord B) layers in which cords are arranged parallel to the circumferential direction, In addition, the cord B is a cord made by twisting organic fiber yarns having a core-sheath structure consisting of a core and a sheath wrapped around the core, and the core has the following formula ▲ mathematical formula, chemical formula, table, etc. It is made of polyethylene naphthalene-2,6-dicarboxylate having the repeating unit shown by ▼, the sheath part is made of polyamide, and the core part is made of three parts of the entire yarn.
The organic fiber cord has the following formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, NT is the twist coefficient, T is the number of twists of the cord (twists/10 cm), and ρ is (The specific gravity of the fibers, D indicates the total denier of the cord.) A cord made by twisting together a first twist and a second twist within a twist coefficient NT of 0.3 to 0.6, A pneumatic tire characterized by having an elongation (E) of 6.0% or less at 2.25 g/d as a cord taken out from a tire product.