JPH05139111A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE:To improve adhesiveness to the coat rubber to prevent edge separation of the terminal part of a carcass layer by constituting the carcass layer of PEN fiber cords processed with an adhesive material having reactivity to the base member fiber and an other adhesive material RFL. CONSTITUTION:A carcass layer 4 of a pneumatic tire is formed of polyethylene-2,6-naphthalate (PEN) fiber cords processed with an adhesive agent having reactivity to fiber, and another adhesive agent, namely resorcinol- formaldehyde-rubber latex (RFL), and a JIS-A altitude 50-80 coat rubber. Thus, adhesiveness to the coat rubber can be improved, and edge separation of the terminal part of the carcass layer can be prevented. Further, since the fiber cords are covered with the coat rubber JIS-A altitude, the difference of modulas between the PEN fiber cords and the coat rubber is reduced to improve fatigue resistance and to reduce the stress concentration applied to the terminal part of the carcass layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire having improved driving stability and durability during high speed running.

[0002]

2. Description of the Related Art Polyethylene terephthalate fiber (hereinafter PE) is used as a carcass layer of a pneumatic radial tire for passenger cars.
A cord (abbreviated as T fiber) is mainly used. However, since this PET fiber has a large decrease in modulus at high temperatures, there is a problem in handling stability during high-speed traveling. As a tire for solving such a defect of the PET fiber cord, JP-A-50-55004 discloses a pneumatic tire using polyethylene-2,6-naphthalate fiber (hereinafter referred to as PEN fiber) cord in a carcass layer. Radial tires with interior are proposed. However, this P
Since the EN fiber has low adhesiveness to rubber, edge separation of the carcass layer terminal part turned up especially around the bead core is likely to occur, and since the modulus is large, the fatigue resistance of the cord is poor and the PET fiber cord is used. It had a drawback that its durability was lower than that of tires.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to improve the adhesion of PEN fiber cords to coated rubber when the carcass layer is made of PEN fiber cords to improve steering stability during high-speed running. An object of the present invention is to provide a pneumatic radial tire having improved durability by improving fatigue resistance.

[0004]

The pneumatic radial tire of the present invention which achieves the above object has an adhesive having a reactivity with a fiber and a resorcin-formaldehyde-former.
Polyethylene-2,6-naphthalate fiber cord treated with adhesive agent of rubber latex (RFL) and JIS-
The carcass layer is composed of a coated rubber having an A hardness of 50 to 80.

By thus forming the carcass layer from the adhesive having reactivity with the base fiber and the PEN fiber cord treated with the adhesive of RFL, the adhesion to the coat rubber can be improved. Therefore, the edge separation of the carcass layer end portion can be prevented. Further, by covering with the above-mentioned coated rubber having the JIS-A hardness, the difference in modula from the PEN fiber cord is reduced so that the fatigue resistance is improved, and moreover, the stress concentration applied to the end portion of the carcass layer is reduced. This can be reduced to further enhance the above-described effect of preventing edge separation. Therefore, the PEN fiber cord is used to improve the steering stability at high temperature, and the tire durability equal to or higher than that of the tire using the PET fiber cord is made possible.

The present invention will be described in detail below with reference to the drawings. As shown in FIG. 1, a pneumatic radial tire of the present invention has sidewall portions 2 and bead portions 7 arranged on both left and right sides of a tread portion 1, and these sidewall portions 2 are
The carcass layer 4 is spanned between the bead portion 7 and the bead portion 7. Both terminals of the carcass layer 4 have bead portions 7 respectively.
Around the bead core 3 is folded back from the inside of the tire to the outside thereof, and the folding end is provided at a position near the lower side of the tire maximum width position of the sidewall portion 2. In the figure, 5 is a belt layer and 6 is a belt cover layer.

The carcass layer 4 is composed of a PEN fiber cord. As the polyethylene-2,6-naphthalate constituting the PEN fiber cord, not only a homopolymer but also 85 mol% or more of polyethylene-2,6- It may be a copolymer composed of naphthalate and a copolymerizable third component of less than 15 mol%. Examples of the third component include naphthalenedicarboxylic acid other than 2,6-naphthalenedicarboxylic acid, terephthalic acid, isophthalic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid, sebacic acid, adipic acid, tetramethylene glycol, trimethylene glycol, diethylene glycol. Etc.

A PEN fiber cord made of such polyethylene-2,6-naphthalate or a copolymer thereof is
It is preferred that its tensile strength is at least 7 g / d. The number of twists imparted to such a PEN fiber cord is
It is determined in consideration of strength, initial modulus, convergence, etc., but the twist coefficient K shown by the following formula is preferably 1700 to 1700.
It is preferable to twist the yarn so that it is in the range of 2500.

[0009] In the above formula, T represents the number of twists (times / 10 cm), and D represents the total number of denier of the cord. The twisted PEN fiber cord is subjected to an adhesive treatment with an adhesive having reactivity with the fiber and RFL. This adhesive treatment is generally carried out by a two-step treatment of treating with an adhesive having reactivity and then treating with RFL.

Examples of reactive adhesives include epoxy adhesives and blocked isocyanate adhesives. The treatment conditions with this adhesive are as follows: 0.5 to 1.5% by weight per fiber weight, 100 to 150
After drying at ℃ for about 3 minutes, at 240-260 ℃ 50-6
Heat treatment is performed for 0 seconds. At this time, the tension applied to the cord is about 0.3 g / d.

Further, the processing condition by RFL is 4
After depositing ~ 5% of RFL, heat treatment is applied at a temperature of 240 to 260 ° C. for 50 to 60 seconds by applying a tension of about 0.2 g / d. Thus, the PEN fiber cord treated with the adhesive preferably has a sum of intermediate elongation at 2.25 g / d and dry heat shrinkage at 150 ° C. in the range of 4.0 to 6.0. The obtained PEN fiber cord is coated with a coat rubber to form a sheet-like carcass layer. For this coat rubber, a rubber having a JIS-A hardness of 50 to 80, which is close to the modulus of the PEN fiber cord, is used. There is a need. It is preferably in the range of 60 to 70.
If the JIS-A hardness of this coated rubber is less than 50,
The difference from the modulus of the PEN fiber cord becomes large,
This leads to a decrease in fatigue resistance of the PEN fiber cord.
Further, the promoting effect of preventing the edge separation of the carcass layer is reduced. Furthermore, by using such a coated rubber having a high hardness, the rigidity of the carcass layer is increased, so that the steering stability can be improved. On the other hand, JI
If the SA hardness exceeds 80, the fatigue crack resistance of the coated rubber deteriorates, which is not preferable.

[0012]

[Examples] As shown in Table 1, the total denier and the number of twists are the same, the adhesive treatment, the physical properties of the cord, and the JIS of the coated rubber.
-Polyethylene-2,6-naphthalene with different A hardness
The tire size in which the carcass layer is composed of the G fiber (PEN) cord is 185 / 70R13, which are the same. 4
Various types of inventive tire 1 and comparative tires 1 to 3 were produced.

For comparison, polyethylene terephthalate fiber (PE having the adhesive treatment liquid and the cord physical properties shown in Table 1 and coated with a coat rubber having a JIS-A hardness of 48 (PE) is used.
T) A conventional tire having the same tire size in which a carcass layer is composed of a cord was manufactured. These five types of tires were evaluated for steering stability (cornering power), edge separation property and durability by the following methods. The results are shown in Table 4. Steering stability: A test tire with an air pressure of 1.9 kgf / cm ^{2 was} mounted on a rim of 13 × 5 J and the load was 450 kgf.
Drive at a speed of 10 km / hr and slip angle 1
The cornering power was defined as the average of the absolute values of the lateral force at 0 ° and 1 ° to the left.

The tire assembled with the rim was left in a room at 80 ° C. for 24 hours and then taken out to measure the cornering power at room temperature under the same conditions as above while the tire was not cooled. Durability : 1 test tire with air pressure of 1.9 kgf / cm ²
Assembled on a 3 x 5J rim, at a speed of 80 km / hr,
The durability was defined as the distance when the tire traveled under the following load conditions until failure occurred.

Loading conditions: Step 1 4 hours running with a load of 450 kg Step 2 6 hours running with a load of 495 kg Step 3 4 hours running with a load of 515 kg Step 4 4 hours running with a load of 580 kg After step 4 a loading of 65 kg every 4 hours The maximum load is increased to 1360 kg, and thereafter, the load is kept at 1360 kg and the vehicle is run until a tire failure occurs. Edge separation property : Air pressure 2.0 kgf / cm ²
The test tire of No. 1 was assembled on a rim of 13 × 5J and the diameter was 1
On a 707 mm room (38 ° C) drum, load 900
After traveling 5,000 km at a speed of 80 km / hr and a kgf, the turn-up part of the carcass layer was cut and the damaged state was observed. The "minority" indicates that the turn-up edge of the carcass layer has a separation of 1 mm or less, and the "crack" indicates that the turn-up edge of the carcass layer has been separated.

[0016] Adhesive epoxies, "Valkabond" and RF in Table 1
The composition of L is shown in Tables 2 to 4, respectively.
The compounding compositions of the coated rubbers 1 to 4 are as shown in Table 5. * 1: 1 means no rubber adhesion, and 5 means 100% rubber adhesion.

[0017] In Table 2, ^{* 1} is "Tenacol" EX-313 (manufactured by Nagase Kasei) ^{* 2} is sodium dioctyl sulfosuccinate (manufactured by American Chanamides).

[0018] In Table 3, ^{* 1} is RF resin (Sumitomo Chemical Co., Ltd.) ^{* 2} is Vulnax International Limited ^{* 3} is Up Latex (Zeon Corporation)

[0019]

[0020] In Table 1, ^{* 1} is "Nipol" 1502 (manufactured by Zeon Corporation) ^{* 2} is 1,2-dihydro-2,2,4-trimethylquinoline ^{* 3} is N-tert-butyl-2-benzothiazyl-sulfenamide Is.

From Table 1, it can be seen that the tire of the present invention has a tire durability equivalent to that of a conventional tire, while having a steering stability (C
P) is improving. On the other hand, the comparative tires 1 and 3 each have significantly lower tire durability than the conventional tires, and the comparative tire 2 has less deterioration in tire durability, but also has lower steering stability.

[0022]

EFFECTS OF THE INVENTION According to the present invention, the carcass layer is composed of the adhesive having reactivity with the base fiber and the PEN fiber cord treated with the adhesive of RFL, so that the adhesion to the coat rubber can be improved. Since it can be improved, edge separation of the carcass layer end portion can be prevented. Also, by covering with the above-mentioned coated rubber having the specific JIS-A hardness, the difference in modula from the PEN fiber cord is reduced, so that the fatigue resistance is improved and the stress applied to the end portion of the carcass layer is also improved. The concentration can be reduced, and the effect of preventing the above-mentioned edge separation can be further enhanced. For this reason, the PEN fiber cord is used to improve the steering stability at high temperatures, and the PET
Allows tire durability equal to or better than tires using fiber cords.

[Brief description of drawings]

FIG. 1 is a half sectional view showing an example of a pneumatic radial tire of the present invention.

[Explanation of symbols]

1 tread 2 sidewall part 4 carcass layer

Claims (1)

[Claims] 1. An adhesive having reactivity with a fiber and a resorcin-formaldehyde-rubber latex (RF).
L) A pneumatic radial tire having a carcass layer composed of a polyethylene-2,6-naphthalate fiber cord treated with an adhesive according to L) and a coated rubber having a JIS-A hardness of 50 to 80.