Alkaline Peroxide Mechanical Pulping of High Density Hardwoods, 1991 International Mechanical Pulping Conference Proceedings

The dominate species for chemically treated mechanical hardwood pulps has been aspen in North America. High density hardwoods such as maple and birch have found only limited uses in mechanical pulps. Low strength properties and the difficulty of impregnating have been the major concerns. With the Alkaline Peroxide mechanical Pulping (APMP)® process, there is more flexibility in impregnation than with conventional bleached CTMP. Five different species were combined to produce an APMP pulp for this study. They were aspen, balsam fir, birch, black spruce, and maple. Three stage impregnation was used since it is beneficial for evening the chemcial application between the different species. The results indicate that a strong, bright pulp can be made using significant (1/3) quantities of maple and birch in combination with aspen and softwoods in comparison to softwood/aspen blends. Eliminating aspen from the hardwood/softwood blend did reduce strength properties, but increased the light scattering coefficient. These results show that species that were previously thought unusable for mechanical pulps can be used in APMP systems.