PURPOSE: To obtain two-component loop sewing yarn having specified values of ultimate tenacity, thermal shrinkage and ultimate tensile strength elongation by feeding the core yarn and the effect yarn of high tenacity, low shrinkage and low elongation into the air jet flow at different over-feed rate.

CONSTITUTION: Two feed yarn strands constituted with high tenacity, low shrinkage and low elongation are fed into the air-jet bulking nozzle at different overfeeding rate from each other to give the objective two-component loop sewing yarn (core/effect) having the ultimate tenacity of ≥40 CN/tex, preferably 48-60 CN/tex, the thermal shrinkage at 180°C of ≤8% thermal shrinkage, preferably ≤5%, the ultimate tensile strength elongation of ≤18%, preferably ≤15%.