Previous papers reported on the yield increase for kraft cooking by using sodium borohydride as a reducing agent and its mechanism¹⁾²⁾ . In the present paper, the effect of using hydrazine or hydroxylamine as a reducing agent was investigated and the reaction mechanism was studied by using hydrocellulose.
It can be concluded on the reaction mechanism that the yield increase of pulp by adding hydrazine or hydroxylamine is due to the increasing resistance to the peeling reaction by making hydrazone or oxime at the reducing end group of the hemicellulose molecule. Since these hydrazone and oxime are easily hydrolyzed in hot alkali, high concentrated addition of these reducing agents in the cooking liquor is necessary to prevent them from the hydrolysis. Namely, if not much amount of these reducing agents are added, no increasing effect of pulp yield is expected.

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Wavy-edged paper sheets will result in “fanning in” at the back edges as they pass through the squeeze impression of the offset press, which makes a dominant source of misregister and wrinkling and is closely related to the handling of paper. It has been tried in this investigation to express the degree of waviness in a quantitative manner by defining the wavy edge number as the product of the average height of waves and their number existing in a unit length of paper edge. The dependence of the wavy edge number upon the difference of relative humidity between paper and atmosphere determined on paper samples of various degree of hygro-expansivity has indicated that the safety limit of deviation of atmospheric humidity over paper humidity, within which only practically tolerable degree of waviness is found, can be greatly affected by the quality of paper.

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