THE FIBROUS ACETYLATION OF VISCOSE RAYON WITH KETENE

(1) THE EFFECT OF CATALYSTS IN ACETYLATION

Abstract

Viscose rayon, which was swollen by soaking in water containing catalysts and water content of which was adequately controlled by pressing and drying, was at room temperature brought into contact with ketene generated from the pyrolysis of acetone and fibrously acetylated.
Using as catalysts inorganic acids such as H₂SO₄, HClO₄ and salts and by using suitable combination of salts, for example, the mixture of NH₃-H₃PO₄-H₂SO₄-NaOH, partially acetylated fine fibers are slightly coloured and not damaged by acetylation, were prepared.
In this reaction, for the purpose of obtaining the uniform high acetylated fibers, it is necessary that fibers should contain adequate water, and in consideration of the consumption of ketene in the process of acetylation, it is desirable that the water quantity should be 40-60% weight of original fiber.
The fibers preswollen with alkali are easily acetylated by ketene as well as by acetic anhydride vapour.