Wax dispersion during recycling of old corrugated containers

Bales of old corrugated containers (OCC) often contain a small percentage of wax-coated boxes. During the recycling process, the petroleum waxes are dispersed in the furnish, leading to runnability problems and diminished sheet quality. Laboratory tests were conducted to determine how the thermal properties of various waxes affect their behavior in papermaking systems. Results show that the mass of dispersed wax is a function of temperature. This relationship is described by a sigmoid curve that climbs only after the onset of the wax's melting transition. Deposit formation was greatest between the end of the waxes' solid-solid phase transition and its melting point. These lab results guided the development of a new dispersant that reduces the melting transition of wax coatings. Testing shows that the new dispersant substantially improves the breakdown and stabilization of wax contaminants at temperatures typically used for repulping OCC. The dispersant can be used with a polyelectrolyte coagulant as port of a two-step contaminant control strategy in which the wax is first broken down into a stable colloidal dispersion and then removed by coagulating the colloidal particles with the fiber at a clarifier or on the fiber line. Application: Test data demonstrate the effectiveness of a new dispersant that can break down and stabilize petroleum wax coatings from treated corrugated containers. Used in combination with a polyelectrolyte coagulant, the dispersant provides a viable strategy for removing wax contaminants from recycled pulp.