System Development for the Recycling of Polycoated and Wet Strength Containing Food Packaging Materials, 1998 Recycling Symposium Proceedings

Recycling of the high quality fibers used in food packaging materials remains a major challenge due to their polymer laminations and wet strength nature. In the present study, a system based on high consistency pulping was first tested in a laboratory, and then evaluated in a pilot plant scale study. The effects of major variables, that is, pH, temperature and pulping time, on the defibered fiber yield in the repulping stage were examined in a laboratory through a 2 3 statistical experimental design. It showed that temperature and pulping time had a significant impact but pH was not important. A comparison between the polycoated and uncoated paperboard indicated that peeling of the polymer film from paperboard was crucial. In the pilot study, the results indicate that the complete recycling system with high consistency pulping was very effective in defibration. At the repulping stage effective defibration could be achieved at 110°F in 45 minutes and at 12% consistency. Removal of plastics with the detrash plate in the pulper, the pressure screens and cleaners was essentially completed. Pulps recycled from the base paperboard and cartons were similar and both were superior to normal OCC and MOW pulps.