JAPAN TAPPI JOURNAL

Show abstractHide abstract

The cooking of Abies Sachaliensis by ammonium bisulphite is investigated, and at the same time the cooking is compared with those by Na base bisulphite and neutral ammonium sulphite. The results are as follows :
1) The cooking velocity by the liquor of ammonium bisulphite, showing its pH 2.8, is greater than that of neutral ammonium sulphite. The complete pulping is performed by the liquor more than 5 % SO₂ concentration at 140°C, or more than 2.5 % SO₂ concentration at 150°C in the case of the cooking time is limitted to 4 hours. The cooking ability of NH₃ base is superior to Na base. To have the same cooking degree in the case of using Na base compared with that of NH₃ base, the cooking temperature must be elevated about 610°C, when another conditions are unchanged. The resulting pulp of Na base shows the almost same properties as the NH₃ one, excepting some superiorities in its colour and some greater folding number than the latter one. (Japanese report, Fig. 1, 2, 3, 12)
2) The elongation of the cooking time from 4 to 10 hours is correspondent to the elevelation of the cooking temperature about 10°C, and the properties of 10 hours cooking pulp resulted, excepting some lower hemicellulose content, are the same with those of 4 hours cooking pulp. (Japanese report, Fig. 1, 2, 3, 9, 10).
3) Considering from the degree of SO₂ consumption, it is decided that the digestion mechanisms by SO₂ in both neutral and acidic mediums must be the same, inspite of the observed difference in both reaction velocities. (Japanese report, Fig. 2, 3)
4) Ammonium bisulphite pulp shows some lower holocellulose content, appreciable higher lignin content and some lower Roe number in comparison with the neutral ammonium sulphite pulp. (Japanese report, Fig. 5, 6, 7)
5) Mannan content of the pulp is 22.5 % lower than the neutral cooked pulp having the same yield. (Japanese report, Fig. 10)
6) The pulp shows the maximum mechanical strength at about 50% yield, and it shows breaking length 12 km, folding number 400 times and specific bursting strength 9, showing superiority in comparison with the maximum value of neutral cooked pulp. But in the range of semichemical pul, the mechanical strength decreases.

View full abstract

Download PDF (1249K)

Two classes of unbleached pulps were obtained by sulfite cooking, varying the heating duration at maximum temperature. Unbleached pulps were purified with hot alkaline solution under various conditions. Refined pulps were acetylated under the condition : pulp 1, Ac₂O 4, AcOH 8, H₂SO₄ 0.15, and the suitability of refined pulp for acetylation were studied. A certain correlation seems to exist between the suitability of refined pulp for acetylation and the vield of the pulp (based on the original wood), and the suitability for acetylation increases in proportion to the decrease of the γ cellulose content or pentosan content of refined pulp. But the pentosan may not have direct connection with the suitability for acetylation because no relation is said to exist between the pentosan content of cold refined pulp and the turbidity of the acetylation mixture.

View full abstract

Register with J-STAGE for free!