Mullinix Packages Inc., Fort Wayne, Ind., was an early mover in thermoformed PET packaging, helping pioneer the use of CPET in the early 1980s, according to Tim Love, v.p. of sales and marketing. Speaking at this February’s Packaging Conference in Orlando, Fla. (see story, p. 13), Love detailed Mullinix’s recent work to advance PET, pairing it with a proprietary oxygen scavenger developed with packaging innovator Boh Tsai (holder of patents at American Can, Amoco, and Ciba) to create “glass-clear” packaging that can maintain zero oxygen permeation for more than 4 yr. Even at that point, the company says the amount of headspace oxygen is still lower than the initial level.
Love said Oxy Rx prevents oxidation of foods and drinks, protecting flavor while maintaining clarity for low-temperature APET applications, as well as the ability to be crystallized into an opaque package that can withstand retort sterilization of 260 F and oven reheating to 400 F. In addition, the package is still acceptable in the PET recycling stream.
Among its other novelties is a “designable” shelf life of anywhere from 4 to 24 months. Zero oxygen permeation over 4 yr was achieved in a package with a very high surface-to-volume ratio and fairly thin (20 mils) sidewalls.
Perhaps most novel is that the barrier can be put on hold until its needed. “We can create a dormant state,” Love said. “We can put Oxy Rx to sleep for a period of time until it needs to be used. That way, we’re saving the capacity for that scavenger to be effective.” For example, Love showed testing where the packaging didn’t start consuming oxygen until after 14 days in inventory.
At present, there are no commercial products on the market using the technology, but several applications are undergoing tests to confirm shelf life.