Standardization of Variables for Dyeing Cotton Fabric with Five Synthesized Reactive Dyes

This study presents standardization of dyeing variables for dyeing of five synthesized reactive dyes (Red A, Red B, Red C, Orange D and Black BE) on 100 % cotton fabric. These dyes contained sulfo vinylsulfone functionality and were prepared by either reacting cyanuric chloride with H-acid and coupling with the diazotized product of sulfo vinylsulfone/sulfo tobiaz acid or reacting diazotized sulfo vinylsulfone with H-acid/sodium napthonate under optimized conditions. Different variables which affect the process of dyeing like dye concentration, dyeing temperature, pH of dyeing solution, dyeing time and concentration of auxiliaries used during dyeing were systematically evaluated. All measurements were made at wavelength maxima (λmax) of respective dyes Red A (540 nm), Red B (535 nm), Red C (530 nm), Orange D (520 nm) and Black BE (630 nm). The results showed that 3 % dye concentration was adequate for maximum dye absorption on the cotton fabric and 1 % was ideal for fastness to sunlight and wash. The optimized values for other variables were, dyeing temperature: 80 ºC, pH of dyeing: 11.0, drying time: 90 min; and 80/85 g/L of sodium chloride and 20/25 g/L of sodium carbonate as auxiliaries for 1 % and 3 % dye concentration respectively