| 摘要 |
A method of preparing a nonwoven web of poly(vinyl alcohol) fibers which involves the steps of (1) preparing an aqueous polymer solution of a defined poly(vinyl alcohol); (2) extruding the resulting polymer solution under defined conditions through a die having a plurality of orifices to form a plurality of threadlines; (3) attenuating the resulting threadlines with a defined primary gaseous source to form fibers under conditions of controlled macro scale turbulence and under conditions sufficient to permit the viscosity of each threadline, as it leaves a die orifice and for a distance of no more than about 8 cm, to incrementally increase with increasing distance from the die, while substantially maintaining uniformity of viscosity in the radial direction, at a rate which is sufficient to provide fibers having the desired attenuation and mean fiber diameter without significant fiber breakage; (4) drying the attenuated threadlines with a defined secondary gaseous source; and (5) depositing the resulting fibers randomly on a moving foraminous surface to form a substantially uniform web, the moving foraminous surface being from about 10 to about 100 cm from the opening from which the last gaseous source to contact the threadlines emerges, which fibers have a mean fiber diameter in the range of from about 0.1 to about 30 mu m and are substantially free of shot, with the attenuating and drying steps being carried out under conditions of controlled macro scale turbulence. <IMAGE> |
