| 摘要 |
In order to solve the above problems, the present invention relates to a method for preparing a polyester multifilament for a tire cord, wherein the temperature gradation of quenching air is provided to decrease the difference in the degree of orientation between an inside and an outside of the filament and increase the degree of orientation of an external surface layer, thereby improving heat resistance and chemical resistance of a dip cord. In preparing a polyester multifilament having excellent dimensional stability, heat resistance, and chemical resistance for a tire cord, provided is a method for preparing a polyester multifilament for a tire cord, comprising the steps of: extrusion-melting a solid-phase polymerization polyester chip containing an ethylene terephthalate unit at a temperature of 290-300°C to prepare a spin-out yarn; delay-cooling the spin-out yarn at a temperature of 60-100°C; quenching the cool air temperature to 20-25°C immediately after hot air, followed by solidification; winding a yarn at a spinning rate at which the birefringence and density of the undrawn yarn are controlled; and multi-stage drawing the wound yarn. According to the present invention, a high-strength, low-shrinkage polyester multifilament can be obtained by decreasing the difference in the degree of orientation between the inside and the outside of the filament and increasing the degree of orientation of the external surface layer, and can improve chemical resistance stability and heat resistance due to the increase in the degree of orientation in the surface, thereby being applicable as a tire cord. |
