Dyeing mechanism of sulfur dyes

The sulfur dye is reduced and dissolved into a dyeing solution, and the dyeing cryptochromatic body formed is adsorbed by cellulose fiber, and is treated by air oxidation to make the cellulose fiber show the desired color.
The sulfur dye parent has no affinity for the fiber, and its structure contains sulfur bonds, disulfide bonds or polysulfur bonds, which are reduced to hydrogen sulfide groups under the action of sodium sulfide reducing agent and become hydrochromatic sodium salts dissolved in water. The reason why cryptochromosomes have a good affinity for cellulose fibers is that the dye molecules are larger, which in turn produces a large van der Waals force and hydrogen bond force with the fiber.