抄録
The semichemical pulp made from red pine by neutral ammonium sulfite process, a number of phenomena observed in cooking and qualities of the pulps obtained are compared with those of Na base process. The results are as follows:
1. At the same pH condition the cooking velocity by NH3 base is somewhat larger than that by Na base. The cooking by both NH3 and Na bases showing the same amount of SO2 consumed give the same amount of pulps, yielded. (Vide; Fig. 8, 9)
2. As compared to the pulp obtained by Na base that by NH3 base is darker in colour, the same in Roe number and breaking length, and somewhat lower in pentosan content and specific bursting strength. The last quality, is somewhat improved by cooking in higher pH using some pH control reagent. (Vide; Fig. 10, 11, 12, 13)
3. In bleaching the pulp cooked by NH3 base it shows the same degree of brightness as that by Na base with the same pulp yield. (Vide; Fig. 14)
4. To keep the pH of liqur always more than 7 throughout the cooking, the pH of the liquor at the start must be about 9. For this purpose the needed amount of NH3 or NaOH is about 0.4g/ 100cc liquor, which is equivalent to 28% of NH3 needed to prepare the NH3 base liquor of pH 7, containing 2.5% SO2.
