We tried to make dissolving pulp from mangrove (Rhizophora sp.) grown in Southeast Asia. This paper is to illustrate the cooking behavior in Ca-base acid sulfite pulping process.
Cooking speed of mangrove is slower than that of Japanese hard wood (Castanopsis mixed Quercus), but delignification is very easy. And we can get unbleached pulp with low lignin and high relative viscosity (1015).
Compared with hard wood pulp of the same relative viscosity, unbleached pulp made from mangrove is not only excellent in permanganate number, α- and β- cellulose, but tailings are very small. And the pulp yield of each wood is almost the same.
As the wood density of mangrove is high, it can be digested with small ratio of cooking liquor to wood. But when we think of synthetic quality of pulp, there is a limit at about 2.8 (1/kg of chip) in general liquor (T. A. 7.5%, C. A. 1.5%). At this ratio, CaO in combined acid is 30 g per bone dry chip kg.
It is characteristic of mangrove that it admits a very low limit of combined acid in cooking, while Japanese hard wood needs CaO 35g/chip kg.
In filterbility test of viscose, reactivity of mangrove pulp is better than hard wood pulp. Mangrove pulp made from unbleached pulp of relative viscosity 1014, is better in its reactivity than normal pulp of relative viscosity 78. And also in general cooking liquor (T.A. 7.5%, C.A. 1.5%), mangrove pulp made from combined acid containing CaO 3032g/chip kg, is the most reactive.
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