PARTIAL SUBSTITUTION OF HYBRID LARCH AND WHITE BIRCH FOR BLACK SPRUCE IN TMP FOR THE PRODUCTION OF NEWSPRINT GRADE

摘要

Pilot TMP trials on the suitability of substituting hybrid larch and white birch for black spruce were investigated. The purpose was to find suitable supplementary species in mechanical pulping to fill the gap in fibre supply of traditional species such as spruce. The results suggest that partial replacement up to about 30% of black spruce either by hybrid larch or white birch is possible. However, new mechanical and chemical treatment techniques are needed to improve the pulp quality and extend the usage of the less desirable species for producing newsprint or other high quality grades.