The disperse dye is a kind of dye which is insoluble in water (strictly speaking, slightly soluble in water) and forms a highly dispersed form in water by means of a dispersing agent, and is mainly used for dyeing polyester fibers. The chemical structure of most disperse dyes belongs to the monoazo type, which accounts for about 80% of the disperse dyes, followed by about 15% for the indole type and about 5% for other structural types. It is generally believed that the dyeing mechanism of disperse dyes in water is: due to the action of the dispersant, at the dyeing temperature, part of the dye is dissolved in the dyebath to become a dye molecule, and then adsorbed on the surface of the fiber in the form of molecules, at the same time The amorphous region in the ester fiber is expanded at the dyeing temperature to form a cavity sufficient to accommodate the dye molecules, so that the dye molecules are easily diffused in the fiber, and at the end of the dyeing, the previously expanded holes shrink as the temperature decreases. The dye molecules are encapsulated within the fibers such that the dye molecules are ultimately fixed in the fibers in the form of single molecules or low molecular aggregates. Some foreign scholars believe that the crystal form of disperse dyes (ie, crystal form) has an effect on its dyeing properties, but later research results negated this claim. However, the crystal form of the disperse dye is different, and its lattice energy is also different, so the crystal form of the disperse dye has an influence on its commercial processing.
Due to the hydrophobicity of the polyester fibers, the dyeing methods of the disperse dyes generally include a hot melt method, a high temperature press method, and a carrier method. The hot melt method is that the fabric is first padded, dried, and then sent to a hot melt machine for heat fusion at about 200 ° C; the high temperature pressurization method is usually at 120 to 140 ° C, the fiber is puffed to diffuse the dye into the dye. The fiber is internally dyed; the carrier method is to add an organic carrier in the dyebath to cause the fiber to puff and direct the dye to penetrate into the fiber to be dyed