RETICULATE POLYPROPYLENE FIBERS, PROCESS FOR THEIR PRODUCTION, AND RETICULATE FIBER NONWOVEN FABRIC.

摘要

A soln. of isotactic polypropylene in a specific solvent (trichlorofluoromethane) having a pressure higher than an extinction-initiating pressure (LIE) is introduced into a vacuum chamber at a pressure of not lower than the extinction-finishing pressure (LEE), and the chamber is kept at 198-220 deg.C and at a pressure not higher than the extinction-finishing pressure (LEE) to prepare a soln. The resulting soln. is spun under such a condition that melt flow rate (MFR) immediately before extrusion satisfies the following MFR/C = 0.15-0.0014 (TPF-198)-1.74-0.029(TPF-198) (where TPF represents a soln. temp. and C represents a polypropylene concn. (wt.%)) to produce three-dimensionally reticulate polypropylene fibres. Nonwoven fabric is obtd. by opening the fibres.