HOUSTON - End users will be the judge of how far metallocene-catalyzed polyethylenes will penetrate stretch film markets, according to John Cook, research and development manager for Atlantis Plastics Inc. in Tulsa, Okla. Atlantis tested a metallocene linear low density PE and found it improved some strength properties, but end users reported film breakage for light gauges in high-speed pallet wrappers, ``an important part of the market,'' according to Cook. Stretch film containing high levels of expensive metallocene resins also could be perceived as overengineered for most customers' needs.
Cook said metallocene resin blended with regular LLDPE gave superior puncture resistance and higher load containment, and it retained strength after stretching. In puncture tests such films had fewer and smaller punctures that showed less tendency to propagate. But the metallocene blends were more difficult to process than conventional LLDPE.
Stretch film sales are price-sensitive. End users have yet to put a value on what they would pay for film enhancements offered by metallocenes, Cook said at Flexpo '96 in Houston.