Forming processes polypropylene multifilament yarn by melt spinning and yarns formed therefrom

摘要

A method comprising: - forming a molten polymer composition comprising at least one polypropylene and a nucleating agent: - extruding the molten polymeric composition through multiple orifices to form multiple filaments (9) of polymeric lacomposición describing each extruded filaments (9) swelling at the outlet (31) adjacent the orifice; - cooling the filaments (9) in a liquid bath (16), warming the liquid bath to a temperature encuentraentre 50 ° C and 130 ° C and near the crystallization temperature maximum (Tc) of the polymer composition and estandola surface the liquid bath (16) within the distance of swelling at the outlet (31); - collecting the filaments (9) to form a multifilament fiber bundle (28); and - drawing the multifilament fiber bundle (28) with an aspect ratio greater stretched to about 6 to thread formarun drawn multifilament (30), wherein the multifilament fiber bundle (28) is stretched while heating, the source being heat at a temperature between about 120 ° C and about 150 ° C and siendoel residence time of the filaments (9) in the liquid bath (16) long enough to ensure lacristalización filaments (9).