Junya Ishibashi

Mechanism of Surface Roughness Development in Melt Spinning of Blend Fibers for Artificial Hair

Surface roughness is one of the most important characteristics in the production of fibers for artificial hair. It was recently found that the fibers with highly developed surface roughness can be formed in the melt spinning of polyamide 6 (PA6)/poly (ethylene terephthalate) (PET) blend fibers under certain spinning conditions. To elucidate the conditions necessary for the development of roughness on the fiber surface, melt spinning of various combinations of blend polymers was carried out under a wide range of spinning conditions. It was concluded that the surface roughness can be developed when (1) the minor component is a crystalline polymer, (2) the major component is either an amorphous or crystalline polymer, but is melt processable at a temperature lower than the melting temperature of the minor component, and (3) the extrusion temperature is lower than the melting temperature of the minor component. From the wide-angle X-ray diffraction measurement of amorphous co-PA/PET blend fibers, the crystallization of the PET component in the as-spun fibers was confirmed only for the fibers with surface roughness. Differential scanning calorimetry measurement of the as-spun fibers in the heating and cooling processes revealed that the PET component maintained its high crystallizability even after its melting, when the PET component was crystallized and surface roughness was developed in the spinning process.