Propylene Homopolymer for High-Tenacity Fibers and Nonwovens

摘要

Propylene homopolymers having a melt flow index in the range from 3.0 dg/min to 8.0 dg/min can be particularly suited for high-tenacity fibers and yarns and nonwovens. The propylene homopolymers can be produced by a process that can include polymerizing propylene in presence of a Ziegler-Natta polymerization catalyst, an aluminium alkyl, hydrogen and an optional external donor.

主权项

1. Propylene homopolymer comprising at least two propylene homopolymer fractions of different melt flow index, wherein a ratio of the melt flow index of the fraction with the highest melt flow index and the melt flow index of the fraction with the lowest melt flow index is in the range from 3 to 400, said propylene homopolymer being characterized by:
a melt flow index in the range from 3.0 to 8.0 dg/min, a xylene solubles content in the range from 1.5 wt % to 3.5 wt %, a tacticity in the range from 97.0% to 99.0% of mmmm pentads (determined on the insoluble heptane fraction of the xylene insolubles fraction), and a recovery compliance in the range from 4.0·10−4 Pa−1 to 5.5·10−4 Pa−1, with melt flow index determined according to ISO 1133, condition L, at 230° C. and 2.16 kg.