KR20120056479A - Air Injection Radial Tire Using a Hybrid cord including Shape Remember Alloy - Google Patents

Abstract

PURPOSE: A pneumatic radial tire comprising shape-memory alloys is provided to improve high speed durability and control stability without ride quality reduction. CONSTITUTION: A pneumatic radial tire including a hybrid cord comprising shape-memory alloys is composed to improve high speed durability and control stability without ride quality reduction by applying a hybrid cord to a reinforcement belt. The hybrid cord is made of twisted nitinol fiber which is a type of shape memory alloys and nylon 66. The nitinol fiber which is a type of shape memory alloy has a shape memory temperature of 60-150°C, 3-20% strain, and a 0.1-1.30mm diameter.

Description

Air Injection Radial Tire Using a Hybrid cord including Shape Remember Alloy}

The present invention relates to a pneumatic radial tire to which a hybrid cord including a shape memory alloy is applied, and more particularly, a hybrid cord mixed and twisted with nitinol fiber and nylon 66, which is a shape memory alloy that memorizes an original shape at a specific temperature or more. The present invention relates to a pneumatic radial tire that has been applied to a reinforcing belt to improve high speed durability and steering stability without deteriorating ride comfort.

In general, typical performance demands of high-performance tires along with improved performance of the vehicle include high speed durability, steering stability, ride comfort, and noise. However, it is very difficult to satisfy two opposing physical properties at the same time, even though the driving and comfort of tires are required at the same time, it is always a task to satisfy both performances in the study of tires.

On tires, belts are a very important factor in distributing stress from the ground when driving a vehicle and maintaining a ground shape, which affects driving performance, wear and braking performance. Among them, the reinforcement belt serves to maintain tire performance by suppressing the flow of the steel belt when driving the vehicle.

The main characteristics required for these reinforcing belts include heat-resistant adhesion, shrinkage, modulus retention at room temperature and high temperature. Among them, the heat-resistant adhesive force is the most influential factor on the durability of the tire. As a result of the positional characteristics of the reinforcing belt positioned between the tread and the belt which generate the most heat on the tire, the adhesive force must be maintained when the aging caused by high temperature during driving is large. Retraction force has the effect of preventing the phenomenon that the durability is disadvantageous due to the expansion of the tire due to the temperature rise during the shrinkage of the reinforcing belt. Modulus is a factor that affects the ride comfort and steering stability. The larger the modulus of the reinforcement belt, the smaller the change in the shape of the steel belt due to the force transmitted from the outside.

Cords used for tires for passenger cars include polyethylene terephthalate (PET), rayon and nylon. PET cord is disadvantageous in heat-resisting adhesive strength and has a high modulus deterioration at high temperatures, making it difficult to apply a reinforcing belt. Rayon has little shrinkage force and can't be used because it can't support steel belt due to increased cord length at high temperature. Finally, nylon 66, which is widely used today, is the most widely used reinforcing belt material in the world because of its superior heat resistance and low modulus at high temperature. However, since the basic modulus of nylon is very low, there is a problem in that it has an adverse effect on durability performance when applied to a high-performance radial tire having a high possibility of increasing the internal temperature of the tire by high speed driving.

The present invention is to solve the problems of the prior art as described above, an object of the present invention is to provide a pneumatic radial tire that improves high-speed durability and steering stability at high speeds while maintaining a riding comfort.

One aspect of the present invention for achieving the above object relates to a pneumatic radial tire that applies a hybrid cord of shape memory alloy fiber and nylon 66 to a reinforcing belt.

In the pneumatic radial tire according to an embodiment of the present invention, the shape memory alloy fibers are nitinol fibers. The nitinol fiber has a shape memory temperature of 60 to 150 ° C., a strain of 3 to 20%, and a diameter of 0.1 to 1.30 mm.

In the pneumatic radial tire according to an embodiment of the present invention, the nylon 66 has a quantitative fineness of 1000 to 10,000 denier.

In the pneumatic radial tire according to an embodiment of the present invention, the hybrid cord of the nitinol fiber and nylon 66 is 1 to 5% of the volume of the lintinol fiber, the volume of the nylon 66 is 99 to 95%. In addition, the hybrid cord has a leading twist of 100 to 700 TPM.

The pneumatic radial tire according to the present invention applies a hybrid memory of shape memory alloy nitinol fiber and nylon 66 to the reinforcing belt, thereby maintaining the riding comfort by showing nylon 66 characteristics at low speed, and increasing the temperature of the tire at high speed. At a certain temperature or more, the nitinol fiber is stressed to return to the shape before deformation, thereby suppressing tire expansion, thereby improving high speed durability and steering stability.

Hereinafter, the present invention will be described in more detail with reference to Examples. In addition, in the following description of the present invention, a detailed description of related general functions or configurations will be omitted.

The present invention is to replace the existing high-performance radial tire reinforcing belt cord nylon 66 by applying a hybrid cord of the shape memory alloy mixed with nylon 66 to the reinforcing belt to improve the high-speed durability, steering stability 10-15% without deteriorating ride comfort It relates to a pneumatic radial tire. More specifically, the shape memory alloy is preferably nitinol fibers.

In more detail, nylon 66 serves to maintain the ride comfort and steering stability of the tire when used for the reinforcement belt of the tire as the heat resistance, shrinkage, low temperature and low modulus is excellent. However, this can be said that the effect is great only in the low-speed and general economic speed section, when the internal temperature of the tire is increased by high-speed driving, the basic modulus of nylon is low, it can not guarantee the shape stability of the tire. Accordingly, in the present invention, the problem can be solved by mixing the alloy with the nylon 66, which remembers the shape in a specific temperature section, in order to maintain the modulus at a high temperature.

Nitinol is an alloy of nickel and titanium. When Ni and titanium are reacted at a ratio of 1 to 1 for 30 minutes at 400 to 500 ℃, the alloy remembers this shape, and when heated above a certain temperature, it returns to its original shape. The temperature is called shape memory temperature. The shape memory temperature can be set according to the conditions. Using this characteristic, the shape stability problem of the tire when applied to the reinforcing belt by setting the speed range and the temperature range in which the tire expands in volume and the temperature section at that time as the shape memory temperature As it decreases, the steering stability is greatly improved. In particular, nickel-titanium alloys can be applied to tires because they have almost no loss of the ability to memorize the shape even after one million repetitions.

In the pneumatic radial tire according to an embodiment of the present invention, the shape memory temperature of the nitinol fiber is preferably between 60 to 150 ℃. If the shape memory temperature is less than 60 ℃, there is a problem that hinders the behavior of the nylon 66 cord, if the shape memory temperature is higher than 150 ℃ it is higher than the tire heating temperature range that occurs during high-speed running it is difficult to expect the durability effect.

In one embodiment of the present invention, the hybrid cord of the nitinol fiber and nylon 66 may be used to combine the manufacturing method in the act of staging the cord. At this time, the nitinol fiber in the hybrid cord is monofilament, the volume is 1-5% of the total hybrid cord, the volume of nylon 66 is preferably 95-99%. In the hybrid cord, when the nitinol monofilament is less than 1% of the total volume, it is difficult to affect the steering stability since the recovery stress that can support the tire inflation stress at high temperature is relatively low, and when the tire self-weight exceeds 5%, Accordingly, the rolling resistance is increased and the recovery stress of the nitinol fiber is too large, resulting in an unbalanced tire shape, which may cause problems such as abnormal wear.

In the hybrid cord, the number of twists of the upper edge is preferably about 100 to 700 TPM (Twist Per Meter), the diameter of the nitinol fiber is 0.1 to 1.30 mm, and the quantitative fineness of nylon 66 is about 1,000 to 10,000 denier. good. In this case, the strain of the nitinol fiber is about 3 to 20%. If the number of twists of the hybrid cord is less than 100 TPM, tire manufacturing and driving fatigue performance decreases due to the increase in modulus, and if it exceeds 700 TPM, the effect of nitinol fiber is expected to increase when the tire is inflated at high speeds. There is a difficult problem.

By applying the hybrid cord of nitinol fiber and nylon 66 as described above to the reinforcing belt, the tire according to the present invention maintains the riding comfort by exhibiting the properties of nylon 66 at low speeds, and at a certain temperature by increasing the tire temperature at high speeds. At this point, the nitinol fiber is stressed to return to its shape before deformation, thereby suppressing tire expansion, thereby improving high speed durability and steering stability. This uses the characteristics of the shape memory alloy to return to its original shape before deformation above the shape memory temperature.

Hereinafter, the present invention will be described in more detail with reference to specific examples and comparative examples. However, this is for the purpose of explanation and the present invention is not limited thereto.

[Examples 1 and 2]

To prepare a Nitinol fiber-nylon 66 hybrid cord in the configuration as shown in Table 1 below, the physical properties of the cord is shown in Table 1 below.

 Comparative Example 1

The properties of the conventional nylon 66 cord were evaluated under the same conditions as in Examples 1 and 2, and are shown in Table 1 below.

Example 1 Example 2 Comparative Example 1 Kinds Nitinol (0.20) +
Nylon 66 840 D / 2 Nitinol (0.40) +
Nylon 66 840 D / 2 Nylon 66 840 D / 2 Nitinol monofilament diameter (mm) 0.20 0.40 - Nylon 66 kink
(Hayeon, TPM) 470 470 470 Hybrid code
Twist (Stage, TPM) 470 470 470 Cutting strength (kgf, room temperature) 21.2 28.0 13.8 Cutting strength (kgf, 100 ℃) 20.4 27.4 9.2 Elongation at break (%, room temperature) 16.5 14.2 18.9 Heat adhesion
H-Test (kgf / 9.5mm) 15.8 15.4 14.8

[Property evaluation]

1) Cutting strength and elongation at break are measured according to ASTM D885.

2) Heat-resistant adhesion is in accordance with H-Test ASTM D4776, the adhesive strength was measured after aging at 100 ℃ for 24 hours.

As can be seen from the cutting strength at a high temperature of 100 ° C. in Table 1, the reduction of physical properties at high temperature reduces the nitinol fiber of the hybrid cord, and also shows a better result than the comparative example in the heat-resisting adhesive strength due to the difference between metal and rubber. It can be seen that the strong drop by temperature is greater than the strong drop.

[Test Examples 1 and 2]

    The hybrid cords of Examples 1 and 2 were applied to the reinforcing belts to produce tires of the standard as shown in Table 2 below. The driving test results for the tire are shown in Table 3 below.

     Comparative Test Example 1

    The hybrid cord of Comparative Example 1 was applied to a reinforcing belt to manufacture a tire having a standard as shown in Table 2 below. The driving test results for the tire are shown in Table 3 below.

Test Example 1 Test Example 2 Comparative Test Example 1 Tire specification 215 / 45ZR17 215 / 45ZR17 215 / 45ZR17 Hybrid code Example 1 Example 2 Comparative Example 1 Number of Reinforcement Belts One One One Reinforcement belt form Front cover
(Full Cover) Front cover
(Full Cover) Front cover
(Full Cover) Code array density
(ends / inch 28 28 28

     The high-speed running durability and adjustment stability of the tire manufactured as described above, the evaluation of the running stability after high-speed driving was performed as follows, and the results are shown in Table 3 below.

1) High speed driving durability evaluation: It evaluated based on ECE-R30 which is a high speed driving durability test method.

2) Steering Stability Evaluation: The vehicle is equipped with tires and is adjusted by a professional test driver who can detect changes in steering stability and grasp the degree of steering stability. Here, the initial steering stability refers to the steering stability at the initial stage of tire mounting, and the steering stability evaluation after the high-speed driving refers to the steering stability when the tire is warmed up after 30 minutes of running the evaluation tire at 230 km / hr.

division Test Example 1 Test Example 2 Comparative Test Example 1 High speed driving durability (ECE R30) 2 hours 35 minutes 3 hours 04 minutes 2 hours 10 minutes control
stability Early 108 111 100 High Speed (230 km) 123 139 100 tire
Diameter Early 103 108 100 High Speed (230 km) 118 129 100

Item Index: 100 or less (low) <100 <100 or more (good)

      As shown in the results of Table 3, Test Examples 1 and 2 in which a reinforcing belt cord reinforced with a Nitinol fiber-nylon 66 hybrid cord mixed with a shape memory alloy nitinol monofilament fiber were applied to a tire, were used at high speed and durability. And while the steering stability is excellent at high speed, the tire with the existing nylon 66 cord as a reinforcement belt cord has a result of high driving speed durability, low stability at low speed and high speed driving.

       Although the present invention has been described in detail with reference to preferred embodiments of the present invention, the present invention is not limited to the above-described embodiments, and many modifications are made by those skilled in the art to which the present invention pertains within the scope of the technical idea of the present invention. This possibility will be self-evident.

Claims (6)

    A pneumatic radial tire comprising a shape memory alloy fiber and a nylon 66 hybrid cord applied to a reinforcing belt. The pneumatic radial tire according to claim 1, wherein the shape memory alloy fibers are nitinol fibers. 3. The pneumatic radial tire according to claim 2, wherein the nitinol fiber has a shape memory temperature of 60 to 150 ° C, a strain of 3 to 20%, and a diameter of 0.1 to 1.30 mm. The pneumatic radial tire according to claim 1, wherein the nylon 66 has a quantitative fineness of 1,000 to 10,000 denier. 3. The pneumatic radial tire according to claim 2, wherein the hybrid cord of nitinol fibers and nylon 66 has a volume of 1 to 5% of the nitinol fibers and a volume of 99 to 95% of the nylon 66. 6. The pneumatic radial tire according to claim 5, wherein the hybrid cord has a leading twist of 100 to 700 TPM.