Lightfastness of the Reactive Dyes of Monochloro-s-Triazine Type

Abstract

Lightfastness of the most of the dyeings on cotton when using reactive dyes is poor. In this work the effect of CuSO4, the blend of CuSO4 and K2Cr2O7, Al2(SO4)3 · 18H2O and FeSO4-7H2O on cotton fabrics dyed with red and blue reactive dyes of monochloro-s-triazine and bis(monochloro-s-triazine) type was examined. The results showed the lightfastness of pale red monochloro-s-triazine dyeings treated using CuSO4 and K2Cr2O7, increases even for 3.5 points. The parallel effect is a change of the colour tone of the dyeings. Increased lightfastness was evident also on the other red dyeings. Dark red dyeings, aftertreated with FeSO4 · 7H2O showed also better lightfastness. Lightfastness of the blue dyeings after the same treatment with CuSO4 increased only on the dyeings in dark tones but not more then for 1 point. The change of the colour- tone was smaller. Aftertreatment with FeSO4 · 7H2O increased lightfastness of pale and dark blue dyeings of anthraquinone and formazane type up to the highest rating 8. The change of the colour tone was evident.