抄録
In this paper, we report on the effects of SO2 concentration and addition of the relief liquid to the cooking acid for the properties and yields of sulphite rayon pulp, from the coniferous woods.
The higher the SO2 concentration, the yield of pulp becomes greater at same Sieber No. and in another words, Sieber No. of pulp is lower at the same yield. Consequently it is no doubt that the cooking liquor with higher SO2 contents is preferably used to cook the pulps for paper making.
At digestiong with the lower SO2 cooking acid, alpha-cellulose content of such pulp is slightly higher than the former and even in the low viscosity range it does not fall rapidly.
From these results we can not assert which SO2 concentration is more suitable to cook rayon pulp.
When the relief liquid from the sulphite digester is mixed to the new acid liquor, the cooking acid easily penetrates into chips, and the yield of the pulp becomes higher with the amount of the relief liquid.
Commercially, in spite of mixing rather more amounts of relief liquid, lignosulfonic acid and sugars are not so much involved in the cooking acid that it does not darken pulp by appearance and have no inimical effects on the pulp properties.
If the such impurities are more excessive in the cooking liquor, it becomes unstable at the final stage of the sulphite digestion and give the undesirable effect on rayon pulp.
