Dyeing Method And Mechanism Of Cationic Dyes

Cationic dye is a special dye for acrylonitrile fiber, the dyeing method is in a weakly acidic (pH value of about 4.5) bathtub, with acetic acid and sodium acetate as buffer, in the presence of dielectric and appropriate amount of additives, close to boiling dyeing. The staining mechanism can be divided into three steps:
(1) The dye cations in the dyeing bath are adsorbed on the surface of the fiber.
(2) The dye cation diffuses from the surface of the fiber to the inside.
(3) The dye cation is combined with the anion group contained in the fiber into a salt bond.
Under normal staining conditions, the last step of salt formation is an irreversible reaction, which can lead to high fastness and uneven staining. The first and last two steps react quickly, and the second step diffuses slowly, which determines the overall staining speed. Due to the large affinity between dyes and fibers, in order to achieve uniform dyeing effect, it is necessary to strictly control the temperature of the dyeing bath, pH value, electrolyte, and dyeing agent.