Film Enhancements Increase Stiffness
Although still in their infancy, Cargill Dow's NatureWorks polylactide (PLA) polymers are well suited to replace incumbent materials in some packaging applications. PLA is a new polymer derived from n...
Although still in their infancy, Cargill Dow’s NatureWorks polylactide (PLA) polymers are well suited to replace incumbent materials in some packaging applications. PLA is a new polymer derived from natural plant sugars extracted from corn.
The resin is readily extruded, and gives enhanced properties when oriented. PLA films show good stiffness, twist retention and sealability.
A facility being built in Nebraska to manufacture the polymer should be on-line in 2002.
Another stiffness booster is Ticona’s Topas cyclic olefin copolymer (COC). When Topas is blended with linear low density polyethylene (LLDPE), a resulting 2-mil monolayer film has significantly greater stiffness than LLDPE alone. “The new blend runs like any LLDPE, but gives a more substantial-feeling film,” reports Mirek Planeta, owner of Macro Engineering & Technology Inc., which ran the blend on a blown film line during NPE. “The COC also improves film clarity and frictional properties like anti-block and slip, as well as sealing and moisture barrier.”
A technological development by Brampton Engineering Inc. has opened up the possibility of new high-barrier film structures. The ISO-therm SCD (streamlined coextrusion die) isolates the processing temperature of various layers in a multi-layer structure, permitting combinations such as nylon and PVDC. Brampton Engineering president Bill Wybenga says it is now “practical to use these materials in a coextrusion structure without the degradation seen in the past.”
The potential new film structures could be used for myriad applications, such as nylon/PVDC for processed meat packaging to PP/PVDC films for retort packaging, to polyolefin/PVDC for industrial packaging. As an alternative to foil-lined paper bags, thick barrier film will be able to run on form, fill and seal packaging machinery.