Preparation and application of a β-cyclodextrin-disperse/reactive dye complex

A disperse and a disperse/reactive azo-dyes were prepared and characterised with spectroscopic methods. The complexes with beta-cyclodextrin were prepared by a dry milling method. The characterisation of the complexes in solid state was performed by C-13 CP MAS NMR, FT-IR, Raman spectroscopies and TGA-DTA analysis. The presence of the complexes in solution was evidenced with ESI-MS experiments. The products were used to dye synthetic (nylon, PET), natural (cotton) and cotton-PET blend fibres. Colour intensity and uniformity were evaluated by means of tristimulous colorimetry. beta-Cyclodextrin, used as additive in dyeing baths, enhanced the colour intensity and uniformity of dyed samples. The complexes gave rise to a generalised good result. The disperse/reactive dye showed better fastness to washing properties on nylon 6 and cotton fibres. beta-Cyclodextrin easily substituted the surface active agents, normally used in industrially dyeing processes, without loss in dyeing quality as dyeing uniformity, intensity and washing fastness.