Acetylation of Zein Fibers

The acetylation of zein fibers increased the water-resistance, improved the softness of the fiber by moderation of the severe formaldehyde post-cure, improved the boil-resistance, whitened the fiber by removal of pigments, and decreased the dye uptake. Acetylation was accomplished with acetic anhydride, with sodium acetate or sulfuric acid as catalyst. Acetyl contents of more than 5 percent were quickly obtained in continuous-processing equipment. The amount of acetyl groups introduced can be regulated by changing the composition, time of reaction, or the temperature of the acetylating mixture.