| abstract |
A thermally improved polyester weft yarn is provided by melt-spinning a blend of a polyethylene terephthalate polymer and a small amount of polymer having a glass transition temperature of at least 10° C. higher than that of the polyethylene terephthalate polymer. The yarn has a break elongation of 70% to 200% and a dry heat shrinkage of +5% to -2%, and is capable of withstanding a severe heat-treatment, for example, at 245° C. for 2 minutes during dipping and curing process of a tire cord fabric comprising the same. Even after such heat-treatment, the yarn shows a residual break elongation of more than 60%. Thus, the weft yarn extends uniformly, without breakage, to a toroidal shape during a tire building process, keeping warp cords at a equi-distance relation. A tire cord fabric comprising the weft yarn of the invention finds its use as the carcass in the form of single ply in a radial tire. |