Dissolving pulp which can be utilized for viscose rayon was prepared from bamboo for Burma (Melocanna Bambusoides) through a series of treatments consisting of sulfate digestion and six-stage bleaching including afterhydrolysis by chlorination waste liquor.
Experimental results obtained are as follows;
(I) Both two-stage and one-stage digestions were experimented. In the two-stage digestion, the 1st-stage was carried out at 115°C with 20% of the total chemicals, and the 2nd-stage at 160°C with the remaining 80% of the chemicals. As the 65% of the total silica extracted existed in the waste liquor of the 1st-stage digestion, it seems to be disadvantageous to treat further the 1st-stage waste liquor, thus containing a great quantity of silica, for the sake of its recovery.
(2) Yield of the unbleached pulp were 40% on oven dry basis. Its α-cellulose content was 96%. The yield of the α.cellulose from oven dry chips was similar with that from Akamatsu (P. densiflora) (about 33%).
(3) Analitical data of the bleached pulp and the viscose filtrability were excellent.No significant difference was found between one-stage and two-stage digestions, in these respects.
(4) The qualities of the filaments prepared from this pulp were comparable with those from spruce rayon pulp.

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We studied on quantities of bleaching agents required for conducting three-stage bleaching of Beech NSSC alone and admixtures of Beech NSSC and Red pine sulphite pulp. The results obtained were as follows :
Fully bleached NSSC and mixed pulps obtained by three-stage bleaching process proved of high yield and comparatively superier quality. Remarkable development of strength was the most distinguished characteristic of the these bleached pulps.

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In our country, wood, one of the most important raw and construction materials, is rapidly getting scarce.
From the rational utilization of wood, authors have been carried out this study in order to find whether the rejects in paper mills are suitable as raw material for fiberboard or not.
In this report, the rejects in sulfate pulp mill were used as sample material.
1. Preparation of stock. The rejects (so called knots) were disintegrated with Unimax-Refiner (a kind of vertical type refiner), the stock resulted had following characteristics.
freeness (S.R.) 13.5
alcohol-benzol extracts 0.9%
Lignin (72%H₂SO₄) 24.8%
2. Sheet formation and hot-pressing. The wet fiber sheets were prepared using the laboratory forming box from the suspension of its pulp. Thus obtained wet sheets were pressed holding between wire-gauze and stainless steel plate under next same pressing condition, as the temperature 140°C. the pressure 30 Kg/Cm² and time 20minutes.
In this experiment, rice straw defibrated after cooking with water, as raw material, was used solely or as blended to above reject.
3. Quality
Qualities of thus obtained hardboard were tested depending upon the specification of JIS-A-5903, the figures measured were as following table. From the above table, it will be known that the characteristics of hardboard prepared with sulfate pulp reject (knot) are the impact strength very high and the flexibility is relatively large in comparing with the density of those boards owing to the partial delignification by cooking process.

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