JPS6243305A - Penumatic radial tire - Google Patents

Abstract

PURPOSE:To improve the high-speed durability and steering stability by reinforcing a carcass by the nylon 46 cord having a prescribed twist coefficient, in a radial tire for car. CONSTITUTION:A carcass is reinforced by the nylon 46 cord having a twist coefficient of 1,200-2,100. The thickness of the single filament of the nylon 46 in this case is 3-7 denier. With such constitution, the faculty of a tire such as high-speed durability, steering stability, etc. is improved.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to pneumatic radial tires for automobiles, in particular,
This invention relates to a radial tire for automobiles using a tire cord made of nylon 46 for the carcass of the tire.

(Conventional technology) Traditionally, the carcass of radial tires for automobiles.

It is reinforced with cords of linear material arranged perpendicular to the tire's equator.

As the above-mentioned linear material, fibers such as rayon, polyester fiber, nylon fiber, steel wire, etc. are used, but each has advantages and disadvantages. Tires reinforced with rayon cord have better uniformity than tires using polyester cord, but if water gets into the tire while the tire is running, the strength of the rayon cord decreases, resulting in inferior high-speed durability. . Steel cord has a high specific gravity, making the tire heavy, and if water gets into the tire while the tire is running, the steel cord will rust and its adhesion to the rubber will decrease. Tires using polyester cord are generally made of polyamide fiber, which causes a decrease in the initial modulus of the cord when exposed to high temperatures during driving, and a decrease in cord strength and adhesive strength with rubber due to hydrolysis. The currently used nylon cords made of nylon 6 and nylon 66 have relatively good adhesion to rubber and fatigue resistance, but have large dimensional changes, so tires using conventional nylon cords Since the steering stability of the tire, which is closely related to the rigidity of the tire, and the uniformity of the tire are poor, it is rarely used except for tires of some sizes. On the other hand, nylon 46, which is obtained by high-condensation polymerization of tetramethylene diamine and adipic acid, is known to have a melting point of about 300°C, which is higher than nylon 6 and nylon 66, but it has not been put to practical use as a filament. do not have.

(Problems to be Solved by the Invention) This invention improves the drawbacks of the conventional tires using cords made of various linear materials, and improves tire performance such as high-speed durability and handling stability. be.

(Means for solving the problem) This invention is made of nylon 46 and has a twist coefficient of 1200.
This is a pneumatic radial tire characterized by having a carcass reinforced with ~2100 cord.

This tire cord is made of nylon 46 filament yarn obtained by melt-extruding and drawing nylon 46, which is obtained by high-condensation polymerization of tetramethylene diamine and adipic acid, in the same way as conventional nylon fibers. It is twisted together in the same way. The thickness of the single yarn of nylon 46 filament is preferably 3 to 7 deniers (D), and the cord structure is: 12600/2.12600/3
．． 18900/2 etc. The twist coefficient of the tire cord is calculated by the formula = TXJ (T is the number of twists per 10 cm, D is the total denier of the filaments forming the cord), and the twist coefficient is 1200 to 2100, preferably 1300 to
It is 2050. If the twist coefficient K is less than 1200, the fatigue resistance of the cord will decrease, and if it exceeds 2100, the dimensional change coefficient will be greater than 10%, resulting in a decrease in tire uniformity and reduced steering stability during high-speed running. do.

The above nylon 46 cord has a dimensional change coefficient of 10% or less. The 0 dimensional change coefficient refers to a cord heat-treated after adhesion of resorcin formalin latex (RFL) adhesive under a constant load (2,
Elongation (%) when applying 7g/D) and JIS-L1
It is defined by the sum of the dry heat shrinkage rate (%) at 150° C. for 30 minutes as specified in 017.

In addition, the initial modulus of nylon 46 cord at 120°C is 80% of the initial modulus at room temperature (22°C).
% or more. The initial modulus at room temperature is calculated by calculating the load L (g) when the elongation of the cord is 2% and using the formula □
(However, DaO, 02X Da is the actual denier of the cord) and is a value calculated at 120℃
The initial modulus in is a value calculated by preheating the cord in an oven at 120°C for 2 minutes and then measuring it in the oven in the same manner as above, and using 0.02XDa shrinkage stress (g)].

Furthermore, the nylon 46 cord has high DISC fatigue resistance.The DISC fatigue resistance is based on JIS-L1017, and is repeatedly subjected to a load with an elongation rate of 6.3% and a compression rate of 12.6%, at a rotation speed of 250 rpm, and Strong retention rate after hours (
%).

The nylon 46 cord of the present invention is immersed in an RFL adhesive solution and heat treated in the same manner as conventional nylon cords, and then used as a reinforcing material for the carcass of a radial tire.

(Function) Compared to nylon 6 and nylon 66, nylon 46 has the following properties:
Nylon 46 cord has a high melting point and little change in physical properties at high temperatures.As mentioned above, nylon 46 cord has a small coefficient of dimensional change, so it is suitable for unevenness in tire sidewalls and RF V.
(Radial Fores Variat, 1on)
is small and the tire has uniformity.

In addition, the dimensional change of the tire due to heat during running is small, and the rubber has excellent wear resistance. In addition, nylon 46 cord has a small drop in initial modulus at high temperatures, so it minimizes tire growth and deformation due to increases in tire temperature when running at high speeds, and has excellent wear resistance and crack resistance. Maintains the same level of steering stability as when driving at low speeds. Furthermore, the nylon 46 cord is DI
Since the SC has good fatigue resistance, the cord strength is less likely to deteriorate due to strain caused by repeated compression and expansion while the tire is running, extending the life of the tire and increasing safety.

Example (a) A filament of 1260 denier (300 filaments) obtained by melt-spinning and drawing tire cord nylon 46,
1260D/ with upper twist and lower twist shown in Table 1 below
After manufacturing the cord No. 2 and soaking the cord in RFL adhesive, 3.5 kg was added to the cord in an oven at 250°C.
It was heat-treated under a tension of .

The physical properties of these cords are shown in Table 1 below.

For comparison, the physical property values of each cord of 1260 D/2 of nylon 66, 1500 D/2 of polyethylene terephthalate, and 1650 D/2 of rayon are also listed in Table 1.

(blank below) As seen in Table 1 above, the nylon 46 of this invention
The cord has a smaller initial modulus drop at 120° C. than nylon 66 and polyester cords, and a smaller coefficient of dimensional change than nylon 66 cord. Rayon cord has a small coefficient of dimensional change, but is significantly inferior in tensile strength and DISC fatigue resistance.

(b) Use two layers of lx5x0.25m steel cords for the radial tire belt, and arrange the cord NQB shown in Table 1 in two layers for the carcass with 18/25 ends, size 1
A radial tire of 95/60 R15-86H was manufactured and the performance of the tire was tested. The results are shown in Table 2 below.

Note that the code NnD in Table 1 is used instead of the code NaB.
, E, F, G, and H are also listed.

(Blank below) Table 2 In Table 2, RF V (Radial Force V
ariation) is a grade that indicates the magnitude of force variation in the tire's radial direction when the tire is rotated with the air pressure and load specified in JIS-D4202.
Grade 5 indicates the best, and the unevenness of the sidewall is determined by the internal pressure of 2.
A tire filled with 5 kg/cd is rotated, and the difference between the maximum and minimum values of the concavity of the tire is continuously detected in an angular range of 5 degrees in the circumferential direction of the tire using a strain meter. If there is no difference, it is classified as grade 3. , those with a difference of 0.5 mm or less are classified as 2nd class, and those with a difference of 0.5+m or more are classified as 1st class. High-speed durability is ETRTO standard.
The drum durability under C30 conditions was measured based on the mileage until the tire failed, and polyester cord (
G) It is expressed as an index with the tire used as 100, and the higher the number, the better the high-speed durability. The steering stability is based on the feeling of a test driver on a car driving test course, where O indicates best, O indicates good, and Δ indicates poor.

(Effect of the invention) As shown in Table 2 above, the tire of the present invention has an RFV
The sidewall irregularities are the same as tires using rayon cord, and high-speed durability and handling stability are superior to tires using conventional cord.

Patent applicant: Toyo Rubber Industries, Ltd. Agent Patent Attorney Takeshi Sakano lost Words 1) Ryo Tsukasa

Claims (1)

[Claims] [1] Made of nylon 46, with a twist coefficient of 1200 to 21
A pneumatic radial tire characterized by having a reinforced carcass with a 00 cord.