High molecular weight, medium density polyethylene

摘要

A high molecular weight, medium density polyethylene (HMW, MDPE) is disclosed. The polyethylene comprises from about 85 to about 98 wt % of recurring units of ethylene and about 2 to about 15 wt % of a C3-C10 alpha-olefin. It has a density from about 0.92 to about 0.944 g/cc, a melt index MI2 from about 0.01 to about 0.5 dg/min, and a melt flow ratio MFR from about 50 to about 300. It has a multimodal molecular weight distribution comprising a high molecular weight component and a low molecular weight component. The low molecular weight component has an MI2 from about 50 to about 600 dg/min and a density from about 0.94 to about 0.97 g/cc. A process for making the medium density polyethylene is also disclosed. The process uses a Ziegler catalyst and applies multiple reaction zones.