In areactive dye, achromophore (an atom or group whose presence is responsible for the colour of a compound) contains asubstituent thatreacts with the substrate. Reactive dyes have good fastness properties owing to thecovalent bonding that occurs during dyeing. Reactive dyeing is the most important method for coloringcellulose fibers. Reactive dyes can also be applied onwool andnylon; in the latter case they are applied under weaklyacidic conditions. Reactive dyes have a low utilization degree compared to other types of dyestuff, since the functional group[which?] also bonds to water, creatinghydrolysis.[1]
Reactive dyes had been tested in the late 1800s involving both adding functionalized dyes to the substrate and then activating the substrate first followed by fixation of the dye. The first commercial success was described in the early 1950s. Rattee and Stephens atImperial Chemical Industries (ICI) popularized the chlorotriazines as linkers between the substrate and the chromophore.[citation needed]
Trichlorotriazine remain a popular platform for reactive dyes. The chromophore, with an aminefunctional group, is attached to the triazine, displacing one chloride:[citation needed]
The resulting dichlorotriazine can then be affixed to the cellulose fibre by displacement of one of the two chloride groups:[citation needed]
The fixation process is conducted in a bufferedalkaline dye bath.[citation needed]
An alternative fixation process that is more dominant commercially is the vinylsulfonyl group. Like the chlorotriazines, this functional group adds to the hydroxyl groups of cellulose. The most popular version of this technology is Remazol. The dye is first attached to the ethylsulfonyl group.[citation needed]
Reactive dyes are categorized by functional group.[2][full citation needed]
| Functionality | Fixation | Temperature | Included in Brands |
|---|---|---|---|
| Monochlorotriazine | Haloheterocycle | 80 °C | Basilen E & P, Cibacron E,Procion H,HE |
| Monofluorochlorotriazine | Haloheterocycle | 40 °C | Cibacron F & C |
| Dichlorotriazine | Haloheterocycle | 30 °C | Basilen M, Procion MX |
| Difluorochloropyrimidine | Haloheterocycle | 40 °C | Levafix EA, Drimarene K & R |
| Dichloroquinoxaline | Haloheterocycle | 40 °C | Levafix E |
| Trichloropyrimidine | Haloheterocycle | 80-98 °C | Drimarene X & Z, Cibacron T |
| Vinyl sulfone | activated double bond | 40˚ | Remazol |
| Vinyl amide | activated double bond | 40˚ | Remazol |
Dyestuffs with only one functional group sometimes have a low degree of fixation. To overcome this deficiency, dyestuffs containing two (or more) different reactive groups were developed. These dyestuffs containing two groups are also known as bifunctional dyestuffs although some still refer to the original combination. Some contain two monochlorotriazines, others have a combination of the triazines and one vinyl sulfone group). Bifunctional dyes can be more tolerant to temperature deviations (better process). Other bifunctionals have been created, some with fastness (better quality) or only fixation degree (better environment or economy) in mind.[1]
For more infoFundamental Chemistry of reactive dyesAdvancements in Reactive Textile Dyes
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| Types of dyes | ||
| Traditional textile dyes | ||
| History | ||
| Craft dyes | ||
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