The strength and high melting point of polypropylene makes it the single-most used plastic packaging in the United States and United Kingdom, with 5 billion pounds manufactured in the U.S. alone in 2010.
Although polypropylene is one of the fastest growing areas of plastics recycling, for some end uses it’s important to remove odor and traces of food contamination.
Enter Nextek Ltd., the UK-based plastics-design and -recycling consultant, and a 2013 Recycling Innovators Forum finalist. Nextek has created an innovative process proven to decontaminate food-grade PP for reuse in a closed loop back into food packaging. Is this a game-changer in recyclable plastic food packaging? Quite possibly.
Plastic packaging research: Polypropylene food packaging challenge and proposed solution
With funding from WRAP, the UK government’s recycling-support agency, Nextek developed an innovative two-step polypropylene decontamination process. The initial melting phase reaches nearly 500 degrees Fahrenheit (250 Celsius) to remove contaminant molecules. Next, during solidification under vacuum at about 280 Fahrenheit (140 Celsius), any residual molecules migrate for final removal.
Studies show that the resulting product achieves “the necessary values of food-grade content” that is readily compatible with virgin PP and lacks negative interference from inks and labels, says Edward Kosior, Managing Director, Nextek Ltd. The resulting product can be blended with virgin polypropylene at rates up to 50 percent.
Impact on the plastic packaging industry
Nothing will change in processing and production, but this process would offer packaging decision makers a new stream of material from which to choose as they devise packaging solutions. The recycled polypropylene is suitable for a wide range of foods that contain water or are largely oily, for up to 30 days at temperatures up to 68 Fahrenheit (20C), according to the WRAP/Nextek final report, “Development of a Food-Grade Recycling Process for Post-Consumer Propylene.” Further investigations have shown that the recycled PP can be used at higher temperatures up to 250 Fahrenheit (121 Celsius) for shorter times.
By 2015, Nextek expects to see businesses put the polypropylene decontamination process into production. The first uses could be in non-food applications, but food-grade is expected to follow soon, says Kosior.
Two primary steps remain in bringing polypropylene decontamination full-scale. The first step is to improve process optimization – improving energy efficiency, and modifying final flow property to meet brand owners’ demands, says Kosior.
The second step is improving the systems for separating non-food and food polypropylene packaging, assuring that at least 99 percent of the decontamination process’ input material is food-contact. Already, a WRAP-sponsored research project has developed a system that inexpensively implants laser-detectable identifiers on plastic packaging during molding.
Hear Nextek officials explain their decontamination process at the Recycling Innovators Forum, a showcase for innovative and actionable breakthroughs that can transform recycling. Nine finalists will present to judges and an audience, competing for cash honoraria of up to $20,000. Register for the free event, to be held August 26, 2013, in Louisville, Kentucky, at the Recycling Innovators Forum.