Resumen:
Air consumption in the melt-blowing process represents one of the major costs involved in the production of thin fibers. In the present work an experimental study is conducted on two multihole melt-blowing nozzles for manufacturing styrene-butadiene-styrene based hot-melt adhesive fibers in order to assess their fiber attenuation capability. With this purpose in mind, fiber diameter, fiber temperature, fiber bending, and air velocity were measured experimentally, and the steady-state quasi-one-dimensional longitudinal momentum equation of the slender fiber was integrated numerically in the nozzle postextrusion region and solved for aerodynamic force prefactor K, as it appears in Matsui's drag coefficient correlation. A measure of fiber attenuation efficiency is proposed in terms of prefactor K and other nozzle geometrical and process operating parameters, which indicates the capacity of the nozzle to produce thin fibers with low air consumption. The results indicate that increasing nozzle air tilt angle, prefactor K, and air-polymer kinematic viscosity ratio in turn increases fiber attenuation efficiency. Working conditions are provided for each nozzle design that allow thin hot-melt-adhesive melt-blown fibers to be produced in a cost-effective manner. Furthermore, a formula is provided for estimating the melt-blown fiber attenuation rate in terms of multihole nozzle geometrical and process operating parameters. The results obtained in this work will help to reduce unnecessary energy consumption of melt-blowing equipment.
