INVESTIGATIONS ON THE SUITABILITY OF DOUG LAS-FIR WOOD FOR TMP PRODUCTION .1. IMPORTANCE, CHARACTERISTICS AND PROBLEMS OF THE SPECIES DOUGLAS-FIR

Extractives from Douglas fir are the limiting factor as regards the us e of Douglas fir wood as fibre raw material in the pulp and paper indu stry. They have to date also prevented ist use in the production of TM P. Based on the results of thorough investigations on wood meal the at tempt was made to improve the properties of TMP from Douglas fir by pr etreating the chips. Douglas fir chips from heartwood alone were pretr eated with various metanol-water-mixtures under different conditions. TMPs produced from these pretreated chips were tested by chemical, phy sical and technological as well as optical methods. The cooking liquor s obtained in the course of the pretreatment were analyzed as to their chemical composition and to determine the percentage of dissolved pol ysaccharides and lignin. An assessment was thus possible of the effect iveness of the pretreatment, related to the amount of removed extracti ves. An increase in static as well as dynamic strength properties was recorded for all pretreatment variations. Moreover, an improvement of brightness, depending on the pretreatment, was also achieved.