Abstract
Sodium monosulphite, which is now confronted with the growing demand for semichemical pulp, has attracted some attentions as the cooking agent for pure chemical pulp. The instances thereof are represented by Keebra process in 1920's and others.
Many experimental illustrations and reports published heretofore proof that the superiority of this chemicals depends much on the case, the kinds of material used and the conditions they are disposed.
This report covers the distinguished efficacy of sodium monosulphite as the cooking agent for Manila Waste Rope. The Rope Pulp manufactured by this process gives both extra-high brightness and high strength with splendid cooking yield compared to that processed with conventional alkaline process.This is confirmed experimentally and practically in this report.
The desirable prescription for this kind of raw material seems as follows ; the Waste Rope should be cooked at rather high temperature, say 160°C to 170°C, with the addition of 15 to 18 % chemicals under the shortest duration of cooking hours the equipment affords.
The chemicals, sodium monosulphite, should be unadultered as possible in case the highest brightness and strength are prefered to the pulp. The co-use of any type of buffering alkali gives little effect on both color and strength of the pulp.
The Rope Pulp thus treated by monosulphite process gives the total cooking yield of about 70 % with the brightness of over 70 % and the zerospan breaking length of about 1200 m. The pulp also shows excellent beating adaptability which gives the highest sheet strength in the shortest beater run.The paper manufactured with this Rope Pulp ordinally shows the bursting strength of 75 to 80 points andthe brightness of over 75%, the latter being attained with the abbreviation of bleaching process.
The economical consideration shows that the expensiveness of the chemicals can easily be compensated by the high cooking yield of this most expensive papermaking material though the high economical value of the pulp quality being disregarded.
