Wool-acid dye covalent bonding: the effect of water-soluble carbodiimides

Wool dyed with acid dyes has low wash fastness because of the weak, secondary forces between the fibre and the dye molecule. The amount of covalently fixed dye increases when aftertreating the dyed wool samples with carbodiimides. Several water-soluble carbodiimide derivatives proved to be effective for this purpose. They were synthesised by our method involving the use of: N-propyl-N′-(3-trimethyl-ammoniumpropyl)-carbodiimide-iodide, N-cyclohexyl-N′-(3-trimethylammonium-propyl)-carbodiimide-iodide, and N-cyclohexyl-N′-(2-morpholinoethyl)-carbodiimide-methyl-p-toluene-sulphonate. No damage occurred in the fibre structure during the treatment. The effect of both the carbodiimides and the dyes (Sandolan Fast Blue P-L, Egacyd Yellow T) is discussed.