The raw materials of tire cord fabric include nylon, polyester, viscose filament, para-aramid and steel wire, etc.
The raw materials of tire cord fabric include nylon, polyester, viscose filament, para-aramid and steel wire, etc.
Nylon has a low modulus, poor creep resistance, and a large thermal shrinkage rate. Its cord fabric is prone to the "flat point" effect, which can cause tire deformation. Therefore, it is not suitable for the carcass of radial tires with high rigidity requirements. To enhance its dimensional stability, DuPont has developed a low-line-density nylon 66 shaped fiber called Hyten. Its cross-section is a rounded rectangle with an aspect ratio of approximately 3.
High modulus low shrinkage (HMLS) polyester cord fabric, also known as Dimensionally Stable Polyester (DSP) cord fabric, is suitable for the tire body of passenger car radial tires with high rigidity requirements. However, it will undergo amination at high temperatures, resulting in a decrease in strength. Therefore, it is not suitable for large tires that generate a lot of heat and have difficulty dissipating heat during operation. The first-generation HMLS polyester industrial filament was produced in the 1990s. Since then, its dimensional stability has been continuously improved. Currently, its heat shrinkage rate can reach half of that of conventional polyester, and the modulus has increased by one quarter. Its development goal is to achieve a lower heat shrinkage rate and a higher modulus than viscose filament.
Viscose filament has good thermal stability, and its dimensional stability is far superior to that of nylon and polyester. It has less elastic modulus loss at high temperatures, high handling stability when tires are running at high speeds, and a comfortable ride. Due to its low strength, more fibers are used, thereby enhancing the shear rigidity. However, its wet strength and fatigue resistance are poor, waste liquid is generated during the production process, and the cost is high.
The specific strength and specific modulus of para-aramid are nearly 6 times and 3 times that of steel wire respectively, and 2 times and over 10 times that of nylon 66. It has good resistance to high and low temperatures, and the tires made from it have good steering performance, are comfortable and have a long service life. The composite cord fabric obtained by blending aramid with nylon or polyester can improve its poor resistance to compression and bending fatigue, difficulty in bonding and high cost.