Oxygen-Scavenging Resin Keeps Food Fresher.

A new olefinic oxygen-scavenging polymer (OSP) system for flexible or rigid packaging has been developed by Chevron Phillips Chemical Co., Houston. Start-up of a commercial production unit is scheduled for next July. In multilayer structures, the OSP can be used as an active barrier layer between a passive oxygen barrier such as nylon, EVOH, or PET and an inside layer such as PE or ionomer.

The OSP system is a blend containing about 90% ethylene methyl acrylate cyclohexene methyl acrylate (EMCM) copolymer. This is an oxidizable resin that readily scavenges oxygen without degrading into smaller, undesirable compounds. The other 10% of the blend is a masterbatch of a proprietary nonextractable photoinitiator and a transition-metal catalyst or cobalt salt. This second component keeps the OSP in a latent, nonscavenging state until it is activated by exposure to uv light while the package is being filled.

Chevron Phillips is also working on new "super oxygen barriers" that involve either blending passive barrier resins with an OSP or grafting or copolymerizing OSP functionality onto existing barrier polymers.