Half Dyeing Time Research Articles

Physico-Chemical Studies on Dyeing Process. I. Theory of Dyeing Equilibrium and Half Dyeing Time of Direct Cotton Dyes on Viscose Rayon

Abstract The theory of dyeing equilibrium is treated generally. On the way of derivation, it is emphasized that the Donnan’s equation, f_+f_-[Na][Cl]=f_+^φf_-^φ[Naφ][Clφ] is correct only when Na+ and Cl− have no affinity to the fibre. An equation expressing dyeing equilibrium is obtained for finite liquid yarn ratio, and compared to the equation by Vickerstaff for infinite liquid yarn ratio. Moreover, data for both finite and infinite liquid yarn ratio could be plotted on the same straight line according to the newly derved equation. The deviation of the incilination of the straight line from the theoretical value is attributed to the deviation of the activity coefficient from unity. The latter was assumed as analogous to that of soap, and a reasonable conclusion could be obtained. On the theory of dyeing rate, all data from widely different dyeing conditions are brought into a simple relation (Remark: Graphics omitted.) using the half dyeing time T proposed by Boulton. This equation was justified theoretically, and it was show that Hill’s complicated equation is replaced by this simple equation, without loss of accuracy, as far as x⁄x∞≤0.7. Then, Boulton’s relation, that the half dyeing time becomes longer when the equilibrium exhaustion ratio is smaller, is justified theoretically. The apparent diffusion coefficient in fibre agrees with that of Hanson and Neale.