Manufacturing Process for Cellulose Acetate
Cellulose and acetic acid are mixed in a reactor. During the activation phase the cellulose sheets are broken down into fibers. For acetylation acetic anhydride is added. At the end of the reaction, a solution of cellulose triacetate in acetic acid is obtained. In a subsequent saponification (hydrolysis), the resulting solution is mixed with water in a separate hydrolysis tank, where part of the acetylation is reversed. The reaction is allowed to continue until cellulose-2,5-acetate (dissolved in acetic acid) is obtained. By diluting this solution with water, cellulose-2,5-acetate precipitates rapidly in the form of flakes.Due to their porous structure, the flakes are saturated with acetic acid. Through intensive washing with water this acid is removed. After the washing process, the flakes are first freed of water in a roller press and then in a hot air dryer.
Below: Saponification and Precipitation