Cationic dyes are produced with the development of petrochemicals. In the 1950s, with the appearance of acrylonitrile fibers, cationic dyes for acrylonitrile fibers were developed. China in the early 60s have also been research and development to produce the first generation of a variety of cationic dyes. 70 years and the development of the second generation of X-type cationic dyes, to expand the chromatographic range, improve the dyeing performance, taking into account the compatibility between the ternary color. 70 years of trial production and production of the third generation of M-type cationic dyes, known as the migration of cationic dyes, can be applied to a variety of acrylonitrile fiber dyeing.Cationic Dyes
The world's production of dyes in developed countries, the production of cationic dyes and alkaline dye production accounted for only 10% of the total output of dyes. China's cationic dye production in the 1990s was more than 2 thousand tons / year, accounting for more than 1% of total dyestuff production, but also part of the export. Cationic dyes in the X-type three primary colors and cationic pink FG and brilliant red 5GN for the larger varieties.Cationic Dyes
In recent years at home and abroad to research and development of dyeing performance, special, new structure of the species, as well as the improvement of old products, energy saving, waste management and other fields.
Cationic dyes are acrylonitrile fiber special dyes, dyeing method is weak acid (pH value of 4.5 or so) in the bathtub, acetic acid and sodium acetate as a buffer, in the presence of medium and the amount of additives, close to boiling dyeing. Dyeing mechanism can be divided into three steps:
(1) dye dyes in the dye bath are adsorbed on the fiber surface.Cationic Dyes
(2) dye cation from the fiber surface to the internal diffusion.
(3) Dye cations combine with the anionic groups contained in the fibers.
Under normal dyeing conditions, the final step of salt formation is irreversible, can lead to high fastness and uneven dyeing. The first two steps react quickly, the second step is slow to diffuse, it determines the entire dyeing speed. As the affinity between the dye and fiber, in order to achieve leveling effect, to strictly control the dye bath temperature, pH, electrolyte, slow dye and so on.