METHOD FOR PRODUCING HEAT-GENERATING MACHINE SEWING THREAD

PROBLEM TO BE SOLVED: To obtain a staple fiber blended thread in which metal fibers and synthetic fibers are uniformly distributed on the order of single fibers, and thereby to provide a heat-generating machine sewing thread significantly improved in machine sewing performance as compared to a conventional one.SOLUTION: A method for producing a heat-generating machine sewing thread, in which metal staple fibers and synthetic staple fibers are blended, includes feeding a metal fiber filament bundle and a synthetic fiber filament bundle arranged in parallel with each other to a stretch-breaking apparatus. In the method, the filament bundles are each opened to form flat threads. The flat threads are superposed in the thickness direction of the flat threads and are passed through two pairs of nip rollers having different peripheral speeds in the order of a pair of low-speed nip rollers and a pair of high-speed nip rollers, during which the flat threads are held between the nip rollers of each pair in the thickness direction so as to keep the flatness. The flat threads are stretch-broken between the two pairs of nip rollers and then passed through an air injection nozzle to be conjugated.