Symposium on “Recent Advances in the Colouring of Man‐made Fibres”

Abstract

Successful results in dyeing depend on a series of simultaneous equilibria. The formation of micelles by non‐ionic levelling agents has been demonstrated spectroscopically and the micellar size determined. The equilibrium conditions in the formation of complexes between dyes and levelling‐agent micelles have been studied. These conditions are intimately related to the equilibrium between dye and fibre. The latter equilibrium has been investigated with dyeings on polyamides. Study of the simultaneous equilibria dye‐fibre and dye‐levelling agent gives a clear picture of the nature of the retarding and levelling action of textile auxiliaries. The equilibrium between auxiliary and dye decreases the association of the latter. Results obtained in previous diffusion studies, however, have been interpreted as indicating increased association of dyes on addition of levelling agents. These results have been re‐examined, and shown to be in accordance with the theories developed in the present paper.

The Interaction between Dyes and Nonionic Surfactants: the Mode of Action on Nonionic Surfactants in Dyeing

“…The number of l would be determined by the difference, [S]cmc -[S]*cmc, assuming that [DSJ « [DS,] at [S]cmc. The plots of [S]cmc -[S]*cmc as a function of the concentration of dye give a straight line whose slope gives the value of l, and it was found that the value of l lay in the range from 10 to 30, corresponding to that reported by Luck (1958Luck ( , 1960aLuck ( , 1960b).…”

Interaction of vinylsulphone reactive dyes with cellulosic fabrics. Part 2‐dye associations and dyesurfactant interactions

“…Electronic absorption spectra of dye solutions are known to be directly proportional to the number of unassociated absorbing molecules [10,11]. At constant dye concentration, a decrease in absorbance indicates that aggregation of the dye molecules has occurred in the solution [12].…”

“…The complex interactions between dyes and surfactants are governed by stability constants. A well known method for determining the equilibrium constant of a dyeauxiliary complex can be briefly outlined here [11,13]. Equations can be written to calculate both the aggregation number and the complex association constant of the dye from its absorbance values.…”