Abstract: The present invention relates to a polyester tire cord made of polyester yarn and having a 5% LASE of 1.2 g/d or more as measured according to ASTM D885 at 80° C., a 5% LASE of 1.0 g/d or more as measured according to ASTM D885 at 120° C., and a toughness retention rate of 65% or more at 80° C. and 120° C. The tire cord of the present invention has a modulus comparable to that of rayon even in a high-temperature environment at 120° C. or higher, and has excellent dimensional stability and heat resistance, and thus it can be advantageously applied to a high-performance tire.

Abstract: A polyester tire cord having improved dimensional stability and methods of manufacturing the polyester tire cord are provided. The method includes forming a discharge yarn, extruded while a polyester containing 85 mol % or more of ethylene terephthalate units is melted and passes through a nozzle; forming an undrawn yarn by spinning the discharged yarn; manufacturing a yarn by multistep drawing the undrawn yarn; plying the yarn by twisting; and dipping the plied yard in a dipping solution, and then drying, drawing, and heat-setting the plied yarn before dipping the plied yarn in resorcinol-formaldehyde latex and again drying an heat-setting the plied yarn. An intermediate elongation of the formed polyester tire cord after vulcanization for 20 minutes at 170° C. is E2, an intermediate elongation of the polyester tire cord before vulcanization is E1, and a difference between E2 and E1 is ?E. ?E divided by E1 is 0.5 or less.

Abstract: The present invention relates to a polyester tire cord with excellent dimensional stability which utilizes a yarn manufactured by adjusting spinning and drawing conditions, and a method for manufacturing the same.