Acrylonitrile cationic dyes fibers of special dyes, dyeing method in weakly acidic (pH value of around 4.5) bath, sodium acetate and acetic acid as buffers, in the presence of dielectric and amount of additives, close to the boiling dye. Dyeing mechanism can be divided into three steps:
(1) in the dye bath of dye cations were adsorbed on the fiber surface.
(2) spread of dye cations from the surface to the internal.
(3) cation of dyes and fibers containing anionic groups combined into salt bonds.
Under the normal condition, last step into the salt as irreversible reactions, can lead to high colour fastness dyeing unevenness. Sum of the first two steps, and the second spread slowly, it determines the whole stain speed. Due to the affinity between dyestuff and fiber, for leveling effect is obtained, should strictly control the dye bath temperature, pH, electrolytes, retarding agent.