Effect of surface treatment and wetting behavior on fiber surface and resulted yarn property

A series of spin finishes with various wetting properties was prepared by incorporating different wetting agents into a formulated basic spin finish master batch. They are then applied to poly(ethylene terephthalate) (PET) high-speed melt spinning yarns. The wetting behavior of the fiber surface was evaluated by measuring the on-line spin finish distribution at various distances from the spin finish applicator. The on-line spin finish distribution became more uniform as the distance was increased to 120 cm, indicating that the spin finish continues to spread rapidly on the yarn surface at smaller distances. The variation in mass per unit length along the yarn (yarn evenness) was compared with the corresponding dynamic surface tension of the spin finish emulsion and with the on-line spin finish distribution on the yarn. The yarn evenness was decreased, with a poor on-line spin finish distribution, and with an increased difference between the dynamic surface tensions, Δγd, for bubbling rates of 1 Hz (γ1 Hz) and 6 Hz (γ6 Hz). The on-line spin finish distribution increases with Δγd to a Δγd value of 1.7 dyn/cm. Thereafter, further increasing Δγd causes spin finish splashing from the yarn, reducing the extraction weight of the spin finish from the PET yarn. However, yarn evenness initially decreases as Δγd increases, but levels off when Δγd exceeds 1.7 dyn/cm. Comparing with the surface friction and the surface dielectric property, we conclude that the wetting behavior of the fiber surface played a dominant effect on the PET high-speed melt spinning and, therefore, for the yarn evenness properties produced.