POLYPROPYLENE FIBERS AND FABRICS

摘要

This invention relates to polypropylene fibers and fabrics containing polypropylene fibers, the fibers comprising propylene polymers comprising at least 50 mol % propylene, said polymers having: a) a melt flow rate (MFR, ASTM 1238, 230° C., 2.16 kg) of about 10 dg/min to about 25 dg/min; b) a dimensionless Stress Ratio/Loss Tangent Index R2 [defined by Eq. (8)] at 190° C. from about 1.5 to about 30; c) an onset temperature of crystallization under flow, Tc,rheol, (as determined by SAOS rheology, 190° C., 1° C./min, where said polymer has 0 wt % nucleating agent present), of at least about 123° C.; d) an average meso run length determined by 13C NMR of at least about 55 or higher; and e) optionally, a loss tangent, tan δ, [defined by Eq. (2)] at an angular frequency of 0.1 rad/s at 190° C. from about 14 to about 70.

主权项

1. A nonwoven fabric comprising polypropylene fibers, wherein said polypropylene fibers comprise a propylene polymer comprising at least 50 mol % propylene, said polymer having:
a) a melt flow rate (MFR, ASTM 1238, 230° C., 2.16 kg) of about 10 dg/min to about 21.5 dg/min; b) a dimensionless Stress Ratio/Loss Tangent Index R2 [defined by Eq. (8) herein] at 190° C. from about 1.5 to about 28; c) an onset temperature of crystallization under flow, Tc,rheol, (as determined by SAOS rheology, 1° C./min as described herein, where said polymer has 0 wt % nucleating agent present), of at least about 131° C.; and d) an average meso run length determined by 13C NMR of at least about 97 or higher.