It has been known that ammonia has a good penetrating power into wood systems and a good accelerating action of delignification when it is used in sulphite process as a base. As recently the cost of amminia has fallen so it may be used economically. If the destruction of cellulose and hemicelluloses is avoided by means of the neutral cooking with ammonium sulphite, it might be able to manufacture a pulp for paper making with high yield and good quarities
Abies Sachaliensis is cooked by neutral ammonium sulphite liquor for 5 hours at the cooking temperature, and the time to it is controlled in 1.5 hours in every case.The results of the experiments are shown as follows :
1. The practical temperatures by these neutral cookings lie in a range of 160-180°C, and the cooking at 165-170°C gives relatively good results.
2. In spite of the cooking performed in neutral, the destruction of cellulose and hemicelluloses takes place remarkably because of the relatively high cooking temperature in comparison with the ordinary sulphite process, and the yield of pulps is not so high as expected, but the yield of pulps is resulted 52-53%, showing its Roe number 10 and the holocellulose yield 92-93%.
3. To complete the pulping, the concentration of total SO₂ of liquor is needed more than 5% at 165°C cooking and more than 2.6% at 170°C, but by the elongation of the cooking time makes complete pulping possible by 2.0-2.3% SO₂ liquor.
4. At the waste liquor cooked with less than 5% SO₂ liquor is acidic, the destruction of celluloses must be occured, so if it is controlled to keep neutral by alkali, the yield of pulps is sure to increase.
5. To complete the pulping, the SO₂ consumption against absolutely dry chip is measured in the range of 10-30% in every case, and the amount of the lowest consumption corresponds to the SO₂ consumption calculated in ordinary sulphite cooking.
6. A part of NH₃ used is changed into a component of organic compounds inwaste liquor, which is not liberated by alkali.
7. The mechanical strength of the paper made of these pulps correspond to the strength of kraft paper.

View full abstract

After the model of the previous report, the cooking of beech by neutral ammonium sulphite liquor is investigated, and at the same time the comparision between NH₃ and Na base cooking is made, the results of which are as follows : -
1. Beech is cooked easier than Abies Sachaliensis by this process, and when the cooking time is limited for 5 hours, the optimum cooking temperature is found 160°C.The maximum yield of pulp is 55%, and in higher yield range the pulping is not complete. The pulp includes 23.4% pentosan, showing its Roe number 8.4, the holocellulose yield 92.6%, easy bleachability and good mechanical strength ; these are suitable for paper making. To complete the pulping, the concentration of total SO₂ of liquor is needed more than 4.5% at the cooking tempreature.
2. In the case of cooking by 165°C, 2.5% SO₂, the last pH of liquor drops to 4.5, and the resulting pulp is slightly burned, showing only 43.5% yield : similarly, by 170and 180°C series cooking, lower pulping yield results. The degree of pH drop in the case of beech cooking is more remarkable than Abies Sachaliensis.
3. The cooking velocity is greatly effected by the pH of liquor, and NH₃ base cooking shows tendncy to lead liquor to lower pH than Na base.
4. The cooking velocity by NH₃ base is greater than that by Na base at the same pH condition.
5. Although the pulps resulted by both NH₃ and Na bases give nearly the same qualities for the same yield, the former pulp is slightly superior to the latter in its Roe number, lignin content, holocellulose % and mechanical strength, but somewhat inferior in its color, so it may be said that NH₃ base pulp is more suitable than Na base one for obtaining the bleached pulp.

View full abstract

Mino-gami-what's so called-represents our Japanese-paper which is chiefly manufactured at Maki-dani (=Valley) and Mugei-dani (=Valley) in Mino-Province of Gifu Prefecture, Japan; and it has such kinds as sliding-screen-paper, stencil-paper, and papers for Unbrellas or Sunshades for Woman-use etc. The stencil-paper and the sunshades are both exports for America.
Now, as their materials, paper-mulberry, common-mulberry and Manila-hemp are mainly for the sliding-screen-paper ; gampi-fibre for the stencil-paper by 100%, paper-mulberry for umbrellas.
To mention about the way of paper-making “Flowing-method” is generally employed as was handed down from the ancient times ; this is still prevalent because of its remarkable superiority to “Mechanical-method, ” so far as the fibre-twist-about is concerned.
Manufacturing the stencil-paper, we choose paraffin as its principal ingredient, mix with a small quantity of damar-gum, carnauba wax, stearin, wax etc., solve at 80°C, and then apply them over.
Mino-gami is, as an art, of greater merit in its quality and method ; however, we should endeavour to progress this business by adopting scientific method as well as increasing the product of these materials in future.

View full abstract