Aminochlorotriazine-sulphatoethylsulphone Dyes

Reaction of a dichlorotriazine dye with an arylamine containing a 2- sulphatoethylsulphone grouping is the preferred route to mixed bifunctional reactive dyes capable of reacting with cellulose either via a monochlorotriazine moiety or a vinylsulphone group. A typical example is Sumifix Supra Brilliant Red 2BF (NSK) shown in Figure 1 [1]. Both reactive systems can contribute to the fixation process but the relatively greater reactivity of the vinylsulphone group ensures that most of the fixation arises via this function [2]. Further benefits of this type of structure, however, include the higher substantivity contributed by the triazine bridging residue and the capability this gives to link a sulphatoethylsulphone grouping to a wide range of chromogens.

The presence of two reactive groups that differ in reactivity gives dyes that are less sensitive to exhaust dyeing temperature than typical monofunctional reactive dyes. They can be applied over a wider range of temperatures (50–80°C) and reproducibility of hue in mixture recipes is improved. Moreover, they show minimal sensitivity to electrolyte concentration and are less affected by changes in liquor ratio [3]. Low dyeing temperatures favour reaction via the vinylsulphone group and at higher temperatures the contribution of the chlorotriazine system to fixation becomes more important [4].

The presence of two types of dye–fibre bond has certain consequences for fastness properties. Mixed bifunctional dyes show superior fastness to acid storage than dichlorotriazine or dichloroquinoxaline systems and better fastness to peroxide washing than difluoropyrimidine or dichloroquinoxaline dyes [5]. Conversely, mixed bifunctional dyes do show some of the weakness to alkaline treatments characteristic of vinylsulphone dyes, although less so than monofunctional dyes relying solely on these groups for fixation [6].

An admirable investigation of 18 isomeric dyes of the 7-phenylazo-N- (anilinochlorotriazinyl) H acid series, including CI Reactive Red 194 (Figure 1) and two other commercial products, was reported recently [1]. Allpossible combinations of o-, m-, p-orientation of the sulpho and sulphatoethylsulphonyl groups in the phenylazo and anilino rings at opposite ends of the molecule were evaluated. Interestingly, the three commercially utilised structures showed the highest fixation yields amongst the series of 18 dyes studied.

Reference: 

1. S Abeta et al., J.S.D.C., 107 (1991) 12.
2. U Meyer and S Muller, Text. Chem. Colorist, 22 (1990) 26.
3. S Abeta, T Yoshida and K Imada, Am. Dyestuff Rep., 73 (July 1984) 26.
4. K Imada, M Sasakura and T Yoshida, Text. Chem. Colorist, 22 (1990) 18.
5. S Fujioka and S Abeta, Dyes and Pigments, 3 (1982) 281.
6. M Matsui, U Meyer and H Zollinger, J.S.D.C., 104 (1988) 425.