Fiber Quality in Beverage Cartons -- A Study of Fiber Deterioration During Storage, 1998 Recycling Symposium Proceedings

Before any waste paper furnish is put into a recycling line, it has to be stored for a certain period of time. Depending on the storage conditions and contaminant’s type and levels, fibers may deteriorate and cause the loss of final pulp quality. The objective of the present study was to examine how the quality of fibers in beverage cartons, i.e., milk cartons and drink boxes (MCDB’s) changes along with the storage, with special attention to whether fiber deterioration can be slowed down or stopped by proper material handling procedure before storage. It was found that all parameters studied, including storage time, soaking liquid and handling methods, had a significant impact on the fiber deterioration in the two.packaging materials used. Results indicated that fiber deterioration occurred to a much lesser extent after one month of storage than three months. Even if stored with a substantial amount of residual soaking liquid, fiber strength could still be restored by proper refining after one month’s storage. After three months, however, fiber deterioration was found to be so severe that most of the pulp strength properties were permanently lost. The type of soaking liquids also played an important role. A 50/50 mixture of milk and chocolate milk resulted in much more loss in fiber strength than by orange juice. The experimental observation indicated that there was more mold growth if material was soaked by milk. Removal of the soaking liquid or even drying the materials afterwards slowed down fiber deterioration. It was found that an effective wash after a carton was used would preserve fiber quality well.