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Supercritical CO2 Dyeing Equipment

supercritical dyeing equipment
supercritical dyeing equipment

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

Work principle

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.

Supercritical drying of aerogels

CO2 dyeing process

The CO2 fluid is pressurized to critical pressure through a high-pressure plunger pump, and then heats up to the critical temperature through the preheater, causes the carbon dioxide liquid to reach the supercritical state, then enters into the dye kettle which is put into the dyestuff, fully contact with the dye and dissolve, and the supercritical CO2 with the dye component through the dyeing kettle containing the textile material, the dye enters the textile interior and realizes the dyeing process.

After the completion of the working conditions of the supercritical CO2, so that the CO2 fluid dissolved ability to reduce, and then the unburned dyes and CO2 fluid separation, so that the dye left in the separation kettle, CO2 completely gasification, through the condenser condensate into a liquid for the next cycle of use.


small batch supercritical CO2 extraction machine

Four Features of supercritical CO2 dyeing

  1. Supercritical CO2 dyeing (Waterless dyeing ) the whole process does not need water, dyes can be recycled, dye utilization can reach 100%, without adding additives, greatly saving resources, is a high efficiency and energy saving and environmental protection of High-tech technology.
  2. Ultra-critical CO2 dyeing fabric color bright, do not fade.
  3. Supercritical CO2 dyeing technology, the process of good reproducibility, many batches of dyed fabric colorless poor.
  4. Waterless dyeing technology than traditional dyeing technology requires a short process time, less process.

11 Pros

  • Easy to operate and adjust.
  • Working temperature is 50-80 ℃, Max pressure: 40MPa.
  • Hydraulic or pneumatic quick opening structure with a safety interlock device.
  • Intermittent or continuous work, co-solvent can be added if possible.
  • Low operating temperature to keep the extracts natural.
  • Faster extractions and cold separation processing.
  • The closed loop system recovers 95% of the CO2.
  • No residue of solvent, no nitrate, and ions of heavy metal.
  • Accuracy temperature and pressure control and display system.
  • Fully automated and PLC can be designed.
  • Customized according to customer needs.

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