Aftertreatment of direct dyes on wool and nylon 6 with syntans and a syntan/cationic system

Three different syntans were synthesized by condensation of (1) p-cresol, formaldehyde and 4-hydroxy benzene sulfonic acid, (2) p-cresol, formaldehyde and 6-hydroxy-2-naphthalene sulfonic acid, (3) p-cresol, formaldehyde and phenol, followed by sulfonation; the structures of these syntans were characterized using 1H NMR and FTIR. The effect of aftertreatment with the synthesized syntans, a commercial syntan and a syntan/cation system on the wash fastness of dyed nylon 6 and wool fabrics was determined. Aftertreatment of the dyeings using above syntans improved the wash fastness; further improvement was achieved by the sequential application of a cationic compound to the fabrics.