抄録
To investigate the manufacture of dissolving pulp from red pine by NH3 base SP process, some comparisons between NH3 and Ca base cookings are made. The results may be summerized as follows:
1. Under the same cooking conditions, the results of cookings by NH3 base process differ considerably from those by Ca base process. The NH3 base process gives lower yield of knots and higher yield of pulps, and its observed cooking velocity seems smaller than that of Ca base. (Fig.1)
2. Ca base process with larger amount of combined acid or lower cooking temperature than, those of NH3 base cooking gives almost the same results as NH3 base in specific knot (knot×100/pulp) and the amount of SO2 consummed. But in this case, to obtain the same yield of pulp by both processes, Ca base needs longer cooking time. Hence the practical cooking velocity of NH3 base is larger than that of Ca base. (Fig. 2, 3)
3. In case of NH3 base process, the degree of increase in specific knot by shortening the penetrating time of the cooking liquor is smaller than that in case of Ca base. It may be said that NH3 base with shorter penetrating time the same cooking results as that by Ca base. (Fig.2) is obtainable.
4. The qualities of pulps obtained by both processes are almost the same in unbleached and bleached conditions at the same yield, except of slightly higher value in α-cellulose of unbleached and α-and β-cellulose of bleached pulps by NH3 base. Pulps of both processes are not distingushable in bleaching process. (Fig. 4-14)
From the above, it is concluded that the manufacture of dissolving pulp by NH3 base process is promising.
