Disperse dyes are the only water-insoluble dyes that dye polyesters and acetate fibers. Disperse dyes are a class of non-ionic dyes and are mainly present in water in a highly dispersed state. They are the only dyes that are effective for normal polyesters. Some types are also used for nylon and acetate. Disperse dye molecules are the smallest dye molecules of all dyes. Disperse dyes are also used for the sublimation printing of synthetic fibers and are colorants used in the manufacture of "iron-on" transfer crayons and inks.
Disperse Dyeing Mechanism
The disperse dyes are present as the monomolecular state in dyed polyester fibers. The dye that has been absorbed by the fiber is in a state of dynamic equilibrium with the dye that remains in the bath at the end of the dyeing process. It can be concluded that the transfer of the disperse dye to the fiber takes place from a monomolecular aqueous solution, the concentration of which is maintained during the first phase of the dyeing process by the progressive dissolution of solid dye from the particles in dispersion in the bath. And the following equilibrium situation is set up in the presence of dispersing agents.
Classification of Disperse Dye
Disperse dyes can be divided into five series:
(1) E-type: They have good leveling properties that are suitable for dip dyeing. In addition, some of them can be used in the thermal transfer printing process.
(2) SE-type: They are disperse dyes with general leveling properties and good color fastness, which can be used for dyeing and pad-dry-dye dyeing processes of polyester fibers.
(3) S-type: With high sublimation color fastness, these disperse dyes are mainly used for the pad-dry-dye dyeing processes of polyester blend fabrics.
(4) P-type: They are used for anti-discharge printing of polyester fiber and cellulose fiber blended fabrics.
(5) RD type: They are dyes that can be used for rapid dyeing of polyester fibers. According to the molecular structures of disperse dyes, they can be divided into azo, anthraquinone, nitrodiphenylamine, heterocyclic ring and so on. Due to the lack of water-soluble genes, few disperse dyes are dissolved in water.