JPS6112409A - Aired radial tire for passenger car - Google Patents

Abstract

PURPOSE:To improve the durability of tire by employing aromatic polyamid fiber cord as the reinforcing cord of belt layer having folded portion in plural laminated layers while setting the stranding angle of said fiber cord within specific range. CONSTITUTION:A carcase layer 4 is arranged between a pair of bead sections 1 while plural belt layers V are arranged on the carcass layer 4 at the tread section 3 while crossing each other. Here, the belt layer V is composed of a belt layer Vs employing steel cord S and a belt layer Va employing aromatic polyamid cord 10 formed with a portion A folded to the tread section 3 side. The stranding angle of said fiber cord 10 is set within the range of 31.3-39.9 deg. when measured from acute side against the axis of said cord 10. Consequently, separation at the folded portion A of the belt layer Va is prevented to achieve the purpose.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a pneumatic radial tire for passenger cars, and more specifically, the present invention relates to a pneumatic radial tire for passenger cars. This invention relates to a pneumatic radial tire for passenger cars that has significantly improved durability by preventing peeling failures that occur at the bent portion by improving the aromatic polyamide fiber cord that constitutes the reinforcing cord of the belt layer. be.

[Conventional technology]

Pneumatic radial tires for passenger cars are generally constructed by laminating multiple belt layers with steel cords as reinforcing cords on the tread side of the carcass layer. Durability and high speed due to the arrangement of the belt layer consisting of cords.

It is possible to improve trench longitudinal stability, etc.

However, as described in (-), a radial tire in which a plurality of belt layers each made of a steel cord as a reinforcing cord is laminated has a problem in that the ride comfort deteriorates.

Recently, in order to solve the above-mentioned problems, both ends of the belt layers laminated on the tread side of the carcass layer are bent toward the tread side to form a bent part, and this bent part is Pneumatic radial tires for passenger cars using aromatic polyamide fiber cords as reinforcing cords for the belt layer have been researched and proposed.

However, as shown in -1-M', both layers of the belt layer laminated in multiple layers are bent toward the Treso 1 side to form a folded part, and the folded part is Reinforcement of the belt layer: If aromatic polyamide fiber cord 1 is used as the 1-cord, it will be possible to create a passenger vehicle Φ in which multiple belt layers are laminated using the steel 1-1 described above as the reinforcing cord. ◇Compared to a pneumatic radial tire for commercial use, the ride quality is improved, but the aromatic polyamide fiber coating, its molecular structure, and adhesion to the coated rubber are inferior, and in particular, the folding of the belt layer is poor. At the curved portion, a so-called separation failure occurs in which the aromatic polyamide fiber cord constituting the heald layer and the coated rubber separate, which may reduce the durability of the tire.

Therefore, in order to solve the above-mentioned problem, the inventors of the present invention conducted experiments and studies, and found that both ends of a plurality of laminated belt layers are bent toward the tread side to form a bent portion. When aromatic polyamide fiber cords are used as reinforcing cords for a belt layer having bent portions, there is a significant relationship between the twist angle and the adhesion of the coated rubber. angle,
Measured from the acute angle side with respect to the axis of the cord, 31.3° ~
If the angle is set within the range of 39.3°, the adhesion between the coated rubber and the coated rubber can be greatly improved, and separation failure at the bent portion of the heald layer can be prevented, and the durability of the tire can be greatly improved. We have come to the realization that it is possible to move towards this.

[Purpose of the invention]

The present invention was made based on two consecutive findings,
A pneumatic radial for a passenger car that prevents separation of a belt layer having a folded part among multiple laminated belt layers at the folded part, thereby greatly improving the durability of the tire. The purpose is to provide tires.

[Structure of the invention]

That is, in the present invention, among the belt layers laminated with a plurality of layers,
Both ends are bent toward the tread portion side to form a bent portion, and as a reinforcing cord for the belt layer having this bent portion,
In the pneumatic radial tire for passenger cars using aromatic polyamide fiber cords, the twist angle of the aromatic polyamide fiber cords of the belt layer having the bent portion is 31.3° as measured from the acute angle side with respect to the axis of the cords. ~39.3°
The gist of this invention is a pneumatic radial tire for passenger cars characterized by the following.

〔Example〕

Hereinafter, the present invention will be specifically described by way of examples with reference to the drawings.

FIG. 1 is a partially cutaway perspective explanatory view showing a pneumatic radial tire for a passenger car according to an embodiment of the present invention.

In the figure, E denotes a pneumatic tire according to an embodiment of the present invention, which includes a pair of left and right bead portions 1, a pair of left and right sidewall portions 2 connected to the bead portions 1, and an I-shaped tire located between the sidewall portions 2. Consists of red part 3,
A carcass layer 4 having a cord angle of substantially 90° with respect to the tire circumferential direction is installed between the pair of left and right bead portions 1, and a carcass layer 4 in the tread portion 3 is further installed.
On the top, the cord angle with respect to the tire circumferential direction is 10''~
A plurality of belt layers V are arranged which intersect each other at 35 degrees.

In the present invention, the belt layer V includes a belt layer Vs using a steel cord S as a reinforcing cord, and an aromatic polyamide fiber cord as a reinforcing cord, with both ends bent toward the tread portion 3 side to form a bent part A. The twist angle of the aromatic polyamide fiber cord 10 of the belt layer Va having the bent portion A is 31.3° to 31.3° when measured from the acute angle side with respect to the axis of the cord 10. It is set to a range of 39.3°.

This is because, from the results of experiments described below, when the twist angle θ of the aromatic polyamide fiber cord 10 is less than 31.3°,
This is because the effect of improving the adhesion between the cord 10 and the coat rubber 20 is reduced, and separation occurs at the bent portion A of the belt layer Va having the bent portion A, which deteriorates the durability of the tire. The twist angle θ of cord 10 is 39.
If it exceeds 3 degrees, the effect of improving the adhesion between the cord 10 and the coated rubber 20 will decrease, and the bell having the bent part A)
Separation occurs at the bending part A of JifVa, which deteriorates the durability of the tire. On the other hand, the process of making the aromatic polyamide fiber cord 10 into a single yarn becomes difficult, and it is easily damaged, which deteriorates the physical properties of the cord and deteriorates the quality of the tire. This is because it inhibits the improvement of durability.

In this example, the aromatic polyamide fiber cord used for the aromatic polyamide fiber cord 10 is as follows:
A cord having a tensile strength of 150 kg/**2 or more and a tensile modulus of 3000 kg/**2 or more in its raw yarn has a twist angle θ of 31.3° or more measured from the acute angle side with respect to the axis of the cord. After being twisted so that it has an angle of 39.3 degrees, the surface is adhesively treated.

Further, in this embodiment, the belt layer Va having the bent portion A is
Aromatic polyamide fiber cord 10 of 1000 d
/2, the inclination angle with respect to the tire circumferential direction was 20 degrees, and the number of cords 10 driven per 5011 was 60 when measured perpendicular to the cord direction.

The number of cords 10 inserted per 50 cords is preferably in the range of 40 to 70 cords measured perpendicular to the cord direction. This means that if the number of drives is less than 40,
This is not preferable because it lacks strength as a belt layer. In addition, when introducing the number of inputs of 70, each adjacent code has 1
If the interval between the cords 10 and 0 becomes too narrow, the intrusion of the coated rubber 20 between the cords 10 is inhibited during the manufacturing process, and the adhesive force between the cords 10 and the coated rubber 20 decreases, leading to a decrease in durability. This is not desirable because the number of lines becomes too large, leading to a double layer of costs.

In addition, it is more preferable that the number of cords 10 to be implanted is in the range of 45 to 65 for the reasons mentioned above.

Furthermore, the 100% modulus of the coated rubber 20 is
It is preferably in the range of 30 kg/ct to 70 kg/cxa. This is because the modulus of the aromatic polyamide fiber cord is high, so if the modulus of the coated rubber 20 is less than 30 kg/cJ, the effect of improving the adhesion between the cord 10 and the coated rubber 20 cannot be obtained, and the effect of improving the tire durability cannot be obtained. Because I can't do it, and I'm also 70 kg.
This is because if it exceeds /-, the coat rubber 20 becomes too hard, inhibiting productivity during tire manufacturing and causing an increase in costs, which is not preferable.

Further, in this embodiment, as shown in FIG. 1, the belt layer V includes a two-layer belt layer Vs arranged above the carcass layer 4 and using steel cord S as a reinforcing cord;
It is composed of a total of three layers: the belt layer Va having the bent portion A is laminated on the tread portion 3 side of the two-layer belt layer Vs.

However, the belt layer Va having the bent portion A is not laminated on the tread portion 3 side of the two-layer belt layer Vs using steel cord S as a reinforcing cord as in the present embodiment, and the belt layer Va having the bent portion A is The belt IWVa is placed directly on top of the carcass layer 4, one or more of the belt layers Vs are laminated on the tread portion 3 side of the belt layer Va, and the belt layer V
Of course, both ends of s may be covered with the bent portions A of the bell) IiiiVa.

In the figure, 5 is a bead wire and 6 is a bead filler.

[Experiment example]

Experimental examples will be explained below.

The specifications and test conditions of the pneumatic radial tire for passenger cars used in this experimental example are as follows.

[Specifications of pneumatic tires]

Tire size...195/70HR14 [Carcass layer] (The cord angle to the circumferential direction of the al tire is substantially 90
Double layer arrangement at °.

(BL carcass cord is 1000 d/2 polyester cord.

[Belt layer]

As shown in FIG. 1, there is a two-layer belt layer VS arranged on the upper part of the carcass Fi14 and using steel cord S as a reinforcing cord, and a trend part 3 of the two-layer belt layer Vs.
Consisting of a total of three layers of the belt layer Va having the bent portion A laminated on the side, (belt layer Vs) +al The two layers are arranged so that the cord angle with respect to the tire circumferential direction is 20° and intersects with each other.

(bl code S is steel I x 5 (0,22
) (C) The number of cords inserted per 50 seals, measured perpendicular to the cord direction, is 40.

(d) The 100% modulus of the coated rubber is 55 kg/
c.

(Belt I'fiva) (al) The cords are arranged so that they intersect with each other at an angle of 20' with respect to the circumferential direction of the tire.

(b) Cord] 0 is +000 d/2 aromatic polyamide fiber cord 6 (1 cord per 501 measured perpendicular to Cl direction) Number of cords is 60 Book.

(The 100% modulus of di Cotego J8 is 55 kg.
/(・Iδ.

fe) Aromatic polyamide fiber τl-1' has a tensile strength of 150 kir/fin 2 or more and a tensile modulus of 300 or more.
Uses a cord whose raw yarn has a characteristic of 0 kg/m2 or more.

In the above pneumatic radial tire for passenger cars, the twist angle θ of the cords 10 of the belt layer Va having the bent portion A is as follows: 23.3.27.3.31.3.35.3.39.3.
43.3 were manufactured respectively.

〔Test conditions〕

Rim...5.1/2JJX14゜Pneumatic pressure...
...Bow, 9kg/cIil.

Drum diameter: 1707N.

Speed: 80km/hr.

The initial load is 525 kg, and the load is increased by 5 kg every 2 hours.
The tire weight was increased in increments of 11 kg, and the distance traveled until the tire broke was measured. (Measurement results are shown as an index when the conventional tire is set as 100) As a result of the experiment, the experimental results shown in FIG. 2 were obtained.

FIG. 2 is a diagram showing the relationship between the twist angle θ of the cord of the bell) iitVa having the bent portion A and the durability of the tire.
The vertical axis shows the distance traveled until the tire breaks down, that is, the durability of the tire, as an index, and the horizontal axis shows the twist angle θ of the cord.

From FIG. 2, aromatic polyamide fiber cord 10 was used for the reinforcing cord 1'' of the belt MVa having the bent portion A, and the twist angle θ of this cord was set in the range of 31.3° to 39.3°. It can be seen that the pneumatic radial tire for passenger cars of the present invention can significantly improve the durability of the tire compared to the conventional tire in which the twist angle θ of the cord 10 is 27.3.

In particular, the pneumatic radial tie t-cat for passenger cars of the present invention in which the twist angle θ of the cord 1 is 35.3°, and the conventional tie 1 in which the twist angle θ of the cord 1 is 27.3.
Compared to ・, the durability of tie-1 can be improved by 10%.

As shown in No. 1, No. 31 (2), when the twist angle θ of the cord 10 is in the range of 31.3° to 39.3°, the cord 10 is perpendicular to its axis as shown in the figure. This is because even if the force F acts, shearing deformation is unlikely to occur in the entire cord 10.

In other words, this is the FRR (Fiher) of composite material mechanics.
From the basic idea of the deformation characteristics in forced rubber (reinforced rubber), if the twist angle θ of the cord 10 is less than 31.3°, the cord 10 will receive a force perpendicular to its axis, as shown in Figure 4ia). When F acts, the shape of the cord 10 is deformed into a parallelogram tilted to the left as shown by the two-dot chain line. That is, shear deformation occurs. As a result, the effect of improving the adhesion between the cord 10 and the coat rubber 20 is reduced during running, and separation occurs at the bent portion A of the belt layer Va having the bent portion A, which deteriorates the durability of the tire. Because it forces you.

Furthermore, if the twist angle θ of the cord 1'10 exceeds 39.3 degrees, as shown in FIG.
It transforms into a parallelogram tilted to the right as shown by the dotted chain line. In other words, shear deformation occurs. As a result, during running, the effect of improving the adhesion between the cord 10 and the coat rubber 20 decreases, and a separation occurs at the bent part of the belt layer Va having the bent part A, which also results in the improvement of tire durability. is not obtained.

Moreover, in this case, the process of twisting the aromatic polyamide fiber cord becomes difficult and is likely to be damaged, which may deteriorate the physical properties of the cord and impair the improvement of tire durability.

On the other hand, as in the present invention, the twist angle θ of the cord 10
is in the range of 31.3° to 39.3°, as shown in Fig. 4 (b
), even if a force F perpendicular to its axis is applied to the cord 10, the shape of the cord 10 deforms as shown by the dotted chain line, and shearing deformation is unlikely to occur. . As a result, while driving, code 10 and courtim 2
Separation occurs at the interface with 0 -1! °J', lh
Separation does not occur at the above-mentioned bent portion A of the bottom row Va provided to the bent portion 8. Therefore, the durability of tights can be greatly improved.

〔Effect of the invention〕

As described above, in the present invention, both ends of the heald layer, which is laminated in multiple layers, are bent toward the tread portion to form a bent portion, and aromatic polyamide is used as a reinforcing cord for the belt layer having this bent portion. In a pneumatic radial tire for passenger cars using IJli fiber cords, the twist angle of the aromatic polyamide fiber cords of the belt layer having the bent portions is 31.3° when measured from the acute angle side with respect to the axis of the cords.
Since the angle is set at ~39.3°, it is possible to prevent shear deformation of the aromatic polyamide fiber cord of the belt layer having the bent portion, and to prevent separation from occurring at the interface between the cord and the coated rubber during running. I can do it.

Therefore, it is possible to prevent separation from occurring at the bent portions of the belt layer having the bent portions, and the durability of the tire can be significantly improved.

[Brief explanation of drawings]

FIG. 1C19 A partially cut away perspective explanatory view showing a pneumatic radial tire for a passenger car according to an embodiment of the present invention.
The figure shows the relationship between the twist angle θ of the aromatic polyamide fiber cords of the belt layer having bent parts and the tire durability.
Fig. 3 is a partially enlarged explanatory diagram of a belt layer having a folded portion, and Fig. 4 (b) (c) is a force perpendicular to the axis of the aromatic polyamide fiber cord of the belt layer having a folded portion. It is an explanatory diagram explaining shear deformation when F acts. ■... Bell I layer, Va... Belt layer having a folded part, A... Bending of the belt layer having a folded part. Part, 10・
... Reinforcement cord of the belt layer having a bent part, that is, an aromatic polyamide fiber cord, 20... Coated rubber.

Claims (1)

[Claims] A passenger car air compressor in which both ends of a plurality of laminated belt layers are bent toward the tread portion to form a bent portion, and aromatic polyamide fiber cord is used as a reinforcing cord for the belt layer having the bent portion. The radial tire is characterized in that the twist angle of the aromatic polyamide fiber cord of the belt layer having the bent portion is 31.3° to 39.3° as measured from the acute angle side with respect to the axis of the cord. Pneumatic radial tires for passenger cars.