Retarding agents

摘要

Levelling agents, preferably, cationic levelling agents-are necessary when dyeing polyacrylonitrile fibres to obtain level dyeings, especially, in pale and medium shades. These levelling agents provide safe control of the pick up speed. They also level out the rate of pick up of the components in combination dyeings and promote migration of the dyestuffs on the fibre.Here, a distinction has to be made between retarders and migrating agents, depending on the predominance of the retarding or migratio-promotion action of the cationic levelling agent. Cationic levelling agents have an affinity for acrylic fibre. The affinity of the retarders is higher than that of migrating agents.