Two sulphonated reactive dyes, each carrying a 4-m-carboxypyridinium-1,3,5-triazine-2-oxide (triazinyl betaine) reactive group, were applied to cotton under both alkaline and neutral exhaust dyeing conditions and the dyeings compared to those of related chlorotriazinyl and beta-sulphatoethylsulphonyl based products. The novel reactive dyes displayed good colour yields under alkaline fixation conditions, but unexpectedly performed very poorly under neutral dyeing conditions. The latter result runs counter to the dyeing performance of commercially available dyes of closely related structure (Kayacelon React; Nippon Kayaku). The exceptionally poor neutral dyeing behaviour is believed to be due to low substantivity at elevated temperature, a reactive group of low selectivity in acid medium at high temperature, and in part, to an acid labile dye-fibre bond. (C) 2003 Elsevier Ltd. All rights reserved.
