MULTIFILAMENT EXTRUSION METHOD AND APPARATUS

摘要

Apparatus for producing a multifilament strand wherein the strand is extruded downwardly in heat exchange relationship with a gas is improved according to the present invention by providing the gas as an upwardly flowing annular gas flow surrounding the downwardly flowing filaments. The gas is conducted upwardly parallel to the filaments and thus does not impinge laterally upon the filaments. The extruded filaments entrap ambient air which tends to remain entrained in the downwardly moving strand. The upwardly flowing annular gas stream tends to pull this entrained gas out of the downwardly moving filament thus effectively cooling the filament without causing adjacent strands to impinge upon one another. In this manner, the capacity of the apparatus is increased substantially. Fibers such as polypropylene can be melt spun according to the present invention by passing the molten extruded fibers downwardly inside an annular upwardly flowing heat exchange gas stream. As mentioned, this tends to remove entrained air from the downwardly moving filaments thus effectively rapidly cooling the filaments without causing them to impinge upon one another.