Studies on the Filterability of Cellulose Acetate Solution

Abstract

The effect of raw materials (cotton linter and sulphite and sulphate wood pulps), purifieing temperature of wood pulps in alkali, non-cellulosic material especially pentosan, precipitation conditions of flakes from acetylating bath and surface active agents, and moisture contents of flakes before drying etc., on filterability of these acetate flakes are disscussed.The higher the temperature of alkali purification of wood pulps, the more the homogeneity of the acetate are obtained than the lower one. Pentosan is a undesirable material especially in secondary acetate, but not so in primary one. From these results, it seems that the less purified wood pulp may be used as a raw materials for primary acetate use. The milder the precipitation of flakes from acetilating bath, the more the homogeneity of the flakes are obtained. Also, the stability of the filtrate are disscussed after standing for long time at 30 C. It seems that the change of K2 before and after aging are small for homogeneous flakes. From these result, it was found that the filterability and stability of acetate solution depend not only upon the pulps but also the producing conditions of flakes.