Supercritical CO2 Dyeing Equipment
The supercritical CO2 dyeing equipment (waterless dyeing) is the use of CO2 in the supercritical state of the characteristics of the substitution of traditional water for synthetic fiber dyeing, but also for natural fibers dyeing, not only can be used for fabric desizing, cellulose, fiber-biological materials, such as pre-treatment, can also be used for fabric functional finishing.
Read More: What is Supercritical CO2
The supercritical carbon dioxide instead of water for the dyeing of textiles.
When placed above the critical point, CO2 becomes a remarkable solvent for many natural and synthetic dyes, which are utilized for the coloration of cotton and various synthetic fibers.
The dye solution in the supercritical CO2 is carried to the fiber to be dyed. Under certain conditions, the gas-like diffusion of supercritical CO2 disperses the dye evenly into the small pores and crevices of the fiber. In the dyeing process, the dyestuff powder is fed into the autoclave.
The dyeing equipment is flushed with liquid CO2 and preheated liquidified CO2 picks up the dye and performs dyeing of the package as in solvent dyeing. This dye gets absorbed onto the fiber. When the pressure is released CO2 becomes gaseous and loses its dissolving ability and the dye residues are separated after liquidification.
Carbon dioxide, free from dye, goes back into the collecting tank after completion of the dyeing process. The circulation of CO2 is stopped, dyeing autoclave is depressurized and the unused dye powder gets deposited at the bottom of the machine. Thus, super-critical dyeing does not produce any drainage and may be considered as an eco-friendly dyeing approach.