Disperse dye relative molecular weight is small, the structure is simple, do not contain water soluble groups, is a strong hydrophobic nonionic dyes, dyeing depending on the effect of dispersant with tiny granule dispersed homogeneously in the dye solution. Disperse dye dyeing is characterized by bright color, good color fastness and wide application. Because of disperse dye poorly soluble in water, so most of the dye is with the aid of the effect of dispersant, with small crystal particles dispersed in water, only the dissolved dye molecules can enter into polyester aperture, spread in the fiber itself and the dye, disperse dye solubility with temperature increasing, more than 100 ℃ when more apparent, lace for dyeing of disperse dyes on polyester generally USES the high temperature high pressure dyeing, dyeing has dissolved dye molecules reach the surface of the fiber, fiber surface adsorption, and at high temperature to the fiber internal diffusion, with single dye molecules in the dye solution by adsorption, dye particles melting in the dye solution, Scattered into the micelle dye released continuously, continuously provide single dye molecules, adsorption, diffusion, after dyeing, with the decreasing of temperature, fiber molecular chain segments to stop movement, free volume shrinking, dye and fiber by van der Waals force between the molecules, hydrogen bond and fixation on fiber due to mechanical action, etc. Meanwhile, disperse dyes can also be dyed polyamide, but the fastness of wet treatment is poor. Disperse dyes are the most suitable dyes for dyeing spandex. Especially polyester spandex. It can establish strong intermolecular forces with disperse dye molecules and form a small number of H bonds. Although the polyurethane soft and hard chain segments to make it easy to disperse dye dyeing of microstructure, but also easy to desorption, disperse dye into the fibers easily, but with polyurethane soft segment molecule is very difficult to establish the combination of the strong.