Kraft and Mechanical Pulps from Softwood Commercial Thinnings, 1996 Pulping Conference Proceedings

J.V. Hatton, K. Hunt, W.Y. Gee, and S.S. Johal

Pulp and Paper Research Institute of Canada

The basic density, and the kraft, thermomechanical and chemithermomechanical pulp properties have been determined of commercial thinnings from black, Norway, red and white spruce, and from tamarack and jack pine. The trees varied in age from 17 to 26 years and consisted entirely of juvenile wood. Thinnings had lower basic relative density compared with mature wood of the same species. Kraft pulp yields were good and, with the exception of tearing strength, had sheet properties superior to those from their corresponding mature woods. The thin cell walls of these kraft pulp fibers produced high tensile sheet strengths. Mechanical pulps were brighter and had higher light scattering coefficients than those from the mature wood of the same species. Kraft pulps from thinnings would be ideally suitable as reinforcement fibers in coated and low basis weight papers; mechanical pulps should find use in high value printing grades.