Supercritical carbon dioxide dewaxing of old corrugated containers

Wax-coated old corrugated containers (OCC) are not part of the paper recycl ing stream because a process to remove the wax coating is not presently ava ilable. Residual waxes influence fiber-fiber bonding, reducing the paper pr operties of recycled OCC as well as the paper machine operating efficiency. A procedure to dewax OCC is a major objective of the paper industry. Here we describe a novel process to quantitatively dewax OCC by using supercriti cal carbon dioxide to remove the wax. The results obtained for the extracti on of both saturated and curtain-coated waxed containers are reported and c ompared with Soxhlet extraction with hexane. Quantitative removal of the wa xes was obtained under a variety of operating conditions. Gas chromatograph ic analysis of the extracted paraffin wax shows that supercritical fluid ex traction does not chemically alter the paraffin wax, indicating the recover ed wax may be recycled. (C) 2001 John Wiley & Sons, Inc.