The production process of diacetate fiber tow mainly includes the following steps:
Raw material preparation: First, high-purity cellulose (usually derived from wood pulp or cotton linters) is crushed and alkali-treated to remove impurities such as lignin and hemicellulose to obtain α-cellulose (purity>95%), and then dried to control the water content (usually <5%) to avoid hydrolysis side reactions in the acetylation reaction.
Acetylation reaction: Cellulose and acetic anhydride undergo esterification reaction under the action of a catalyst (such as sulfuric acid) to produce diacetate cellulose ester. The reaction temperature is controlled at 40-50℃ to avoid high temperature causing cellulose degradation.
Spinning process: Dissolve diacetate cellulose flakes in an appropriate solvent (such as acetone) to form a spinning solution. The spinning solution is filtered and degassed before entering the spinning tunnel. The spinning fine stream is solidified into filaments through hot air flash evaporation in the tunnel, and then wound into a tow by a winding roller.
Post-processing process: The initially formed fiber bundles are stretched, coagulated, washed, dried and other processing to obtain the final diacetate fiber bundles.