Abstract
Laboratory studies for direct caustcizing process by ferric oxide in soda quinone pulping conditions were carried out in comparison with kraft pulping. DDA (1, 4-dihydro-9, 10-dihydroxy anthracene sodium salt) was used as quinone with addition of 0.1% as AQ by weight on o. d. wood. In the case of soda quinone pulping of Douglas fir, low temp.-long time pulping at the same H-factor and short time-high alkali pulping at the same τ-factor gave the same Kappa number of pulp, but low temp.-high alkali pulping at the same τ-factor gave a slihgtly high Kappa number pulp. By different pulping conditions, pulp yield and pulp properties were slightly different each other. There are not negligible differences in pulp yield and pulp properties at the same Kappa number by three different Douglas fir chip lot from different pulp mills in Japan. Almost same results with previous reports were obtained by the reappearance tests of soda quinone pulping of Douglas fir and eucalyptus at low Kappa number, and tear strength of soda quinone pulp of Douglas fir was ca. 10% lower than KP by statistical analysis.
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