10. Relation between LR and leveling in the vapor phase in aerodynamic jet dyeing machines

In dyeing by an aerodynamic jet dyeing machine, an exchange of dye liquor proceeds when the fabric passes through the jet nozzle and only the dye on the fabric can contribute to the dyeing until the fabric comes to the next pass.

Then, if the amount of dye on the fabric is less than the amount of dye which can be absorbed by the fabric in one circulation, unlevel dyeing may occur. On the other hand, if the amount of dye on the fabric is more than the amount of dye which can be absorbed, level dyeing can be achieved. In lower LR dyeing, the concentration of dye in the dyebath becomes higher, which is advantageous for level dyeing.

The amount of the dye in the dye liquor contained in the fabric and the dye absorbed by the fabric during one circulation for various LR in PES dyeing with disperse dye is shown in Figure 5.

As shown in Figure 5, the amount of dye absorbed by the fabric in one circulation exceeds the dye on the fiber at the LR=1:15, which may cause unlevel dyeing. But the amount of dye absorbed by the fabric in one circulation does not always exceed the dye on the fiber at the LR=1:5, which perhaps gives a successful result.

Figure 5 Relation between LR and the concentration of dye contained by the fabric

In dyeing by an aerodynamic jet dyeing machine, although the effective area is limited, the amount of dye in the effective area generally increases due to the low LR. Then, a condition where the supply of dye exceeds the absorption of dye is realized and level dyeing can be achieved.