METHOD OF PREPARING A NONWOVEN WEB OF POLY (VINYL ALCOHOL) FIBERS

摘要

A method of preparing a nonwoven web of poly(vinylalcohol) fibers which involves the steps of (1) preparing anaqueous polymer solution of a defined polyvinyl alcohol);(2) extruding the resulting polymer solution under definedconditions through a die having a plurality of orifices toform a plurality of threadlines; (3) attenuating the resultingthreadlines with a defined primary gaseous source to formfibers under conditions of controlled macro scale turbulenceand under conditions sufficient to permit the viscosity ofeach threadline, as it leaves a die orifice and for adistance of no more than about 8 cm, to incrementally increasewith increasing distance from the die, while substantiallymaintaining uniformity of viscosity in the radial direction,at a rate which is sufficient to provide fibers having thedesired attenuation and mean fiber diameter without significantfiber breakage; (4) drying the attenuated threadlineswith a defined secondary gaseous source; and (5) depositingthe resulting fibers randomly on a moving foraminous surfaceto form a substantially uniform web, the moving foraminoussurface being from about 10 to about 100 cm from the openingfrom which the last gaseous source to contact the threadlinesemerges, which fibers have a mean fiber diameter in the rangeof from about 0.1 to about 30 µm and are substantially freeof shot, with the attenuating and drying steps being carriedout under conditions of controlled macro scale turbulence.