The poor exhaustion and fixation properties of Vinylsulphone dyes that lead to lot of dyestuff wastage have given birth to the bi-functional dyes with medium exhaustion and better fixation properties.
Bifunctional dyes have filled a big vacuum of various hues of bright shades, which were not possible with vinyl sulphone type. The dyes were conventional Dichlorotriazine type, with the end condensation of ß-sulphato ethyl sulphone to have different type of reactive group in a single molecule. Being a dual reactive, the primary mode of fixation is from vinyl sulphone group and the dyeing temperature is same as vinyl-sulphone, which enables good, inter compatibility in between the two classes.
These bifunctional dyes are most suitable for exhaust dyeing and Pad Batch and continuous. Can be freely mixed in combinations with Vinyl Sulphone dyes.