Preventing dyestuff migration from one article to another in washing

Abstract

Coloration of quite a share of textiles is not permanent and a part of the dyestuff migrates into the bath in the course of washing. This dyestuff should be kept in the bath, so as to prevent unintentional dyeing of other articles that are washed in the same bath. Surface active agents play a key role in performing this task, as they are able to keep the dyestuff through solubilisation or pigment dispersion. To get a successful solubilisation it is necessary for the surfactant concentration to be above the level of critical concentration, as particles of dyestuffs that are hard to solute are often retained in the micellas. Even better effect is achieved by addding special polymers (polyvynilpirolidon, polyglikolether etc.). They interact with both dyestuffs and surfactants. Solubilisation in these systems takes place even at lower surfactant concentration. The role of a builder is also of key importance, zeolits offering much better effects than Na-triphosphates. Tests performed indicate that the best effect is obtained by employing a combination surfactant-polyvynilpirolidon-zeolit, where no migration of the dyestuff onto a white fabric can be observed. On the other hand, Na-triphosphate has a detrimental impact in the same situation. Zeolits are used in all the developed countries and in the Far East as well.