The fundamental investigation on kraft cooking from the viewpoint of chemical engineering

Part 4 The relationship of cooking degree and pulp quality

Abstract

This paper concerns to investigate the relationship between pulp characteristics (yield, viscosity, sugar composition) and cooking degree in kraft pulping.
The unbleached kraft pulps of Buna (Fagus crenata Blume) and Akamatsu (Pinus densiflora S. et Z.) with various cooking degree were prepared and were bleached with NaClO₂. Pulp viscosity were measured with cupri-ethylene diamine solution and sugar components were analysed by alditol-acetate method. The following informations were consequently obtained.
(1) Little carbohydrate was dissolved and pulp viscosity was dropped only a little during bleaching with NaClO2 when kappa no. of Buna UKP was higher than about 21 and kappa no. of Akamatsu UKP was higher than about 84.
(2) Carbohydrate degradation was obserbed during bleaching with NaClO₂ when kappa no. of Buna UKP was lower than about 21 and kappa no. of Akamatsu UKP was lower than about 84.
(3) The main components of BKP were glucan, xylan in Buna and glucan, xylan, mannan in Akamatsu from analysis by gas chromatography.