Upgrading OCC and Recycled Liner Pulps by Medium-consistency Ozone Treatment

摘要

Possibilities for improving the properties of old corrugated container (OCC) pulp by applying low levels of ozone at medium consistency were evaluated. In addition, pulps obtained from kraft liner and corrugating medium werernconsidered. Ozone reduces the kappa number but the surface charge of the fiber is not changed. Ozonation clearlyrnincreases the relative bonded area (RBA) in sheets made from treated fibers. It was shown that RBA is essential forrnConcora medium test (CMT) resistance. Papermaking properties like tensile strength, internal bond strength,rncompression strength and CMT were significantly increased even at the lowest ozone charge employed. For OCCrnpulp, it is shown that similar improvements can be reached by refining and alkali treatment. Nevertheless, alkali hasrna greater effect on pulp freeness and produces a higher charge in the effluents.