1.1|cents~/lb for Ziegler catalyst. However, Brockmeier said that premium will drop 30-50% as metallocene production increases.
Metallocenes leave different amounts of residues from high-activity Ziegler catalysts, he said.
Narrow-MWD resins made with Ziegler catalyst
"have a tendency to fail ESCR tests for bottles and have a greater tendency toward melt fracture under blow molding conditions," says James Fargher, head of materials and development at Owens-Brockway in Toledo, Ohio.
Unlike the conventional resin made with Ziegler catalysts
, the single-site-formed polymer has a narrow molecular-weight distribution.
This began in the early 1950s with experiments on Ziegler catalysts
for making polyethylene.
"The Unipol II process is designed to use new super-high-activity Ziegler catalysts
as well as emerging new single-site systems," says Polyolefins Div.