Abstract
Acetylated rayon of some 50% acetic acid content can be prepared within 10 minutes, by the action of acetic anhydride and kerosene at above 100°C, on the rayon impregnated with more than 40 % of its weight of potassium acetate from the aqueous solution and then dried. The acetylation reaction not only proceeds smoothly and uniformly, but the rayon suffers no loss of strength nor reduction of D. P. The drawing given to the rayon just after the acetylation improves its properties.
Acetic acid, the by-product of the esterification, retards the acetylation rate. Excess potassium acetate added in the acetylating liquid will produce a double salt, CH3COOK•2CH3COOH, and protect the reaotion rate from its lowering. When the acetylating liquid is cooled, the crystals of the double salt separate from the liquid. Thus acetic acid can be separated and the reactivity of the acetylating liquid is kept constant.
This acetylating process with the retention of fibrous form, the characteristics of which are short reaction time and easy recovery of the chemicals concerned as well as constant reactivity of the acetylating liquid, will make the continuous acetylation of rayon tow successful.
