Investigations on the level dyeing of fabrics in supercritical carbon dioxide

The level dyeing of fabrics in supercritical carbon dioxide was investigated by employing an improved beam (a perforated pipe on which the knitted or woven fabric/warp is wound around). The effects of system temperature, pressure, dyeing time, a time ratio of fluid circulation to static dyeing (Rtime), different fabric layers wrapped around the beam, and the species and chemical structures of dyestuffs on leveling properties and color strength of polyester and cotton fabrics were observed. The results show that the leveling properties and color strength of fabrics were improved on the new beam, as well as with a favorably increased system temperature, pressure, dyeing time, and a time ratio of fluid circulation to static dyeing; while the leveling property and color strength decreased with fabric layers on the beam under an identical condition. Highly leveling results were obtained on polyester and cotton fabrics with disperse and reactive disperse dyes involving different chemical structures.