DIRECT DYES

APPLICATION:

Direct dyes are usually applied with the addition of electrolyte at or near the boil in the machines capable of running at atmospheric pressure. But in HTHP dyeing machines it is carried out at temperatures above the boil in case of pure as well as blended yarns.

An addition of alkali, usually sodium carbonate, may be made with acid-sensitive direct dyes and with hard water as well as to enhance the dye solubilisation. When cellulose is immersed in a solution of a direct dye it absorbs dye from the solution until equilibrium is attained, and at this stage most of the dye is taken up by the fibre. The rates of absorption and equilibrium exhaustion vary from dye to dye. The substantivity of the dye for cellulose is the proportion of the dye absorbed by the fiber compared with that remaining in the dyebath.

*Please refer to our technical for further information.

Properties:-

1. Water soluble dyes

2. Anionic nature

3. Needs electrolyte for exhaustion.

4. Dyeing process is carried out in alkaline condition.

5. Generally applied for cellulosic as well as protein fibers.

6. Fastness properties are average specially wet fastness.

7. Fastness properties are improved by after treatment.

8. It is not widely used as compared with reactive dyes.

9. Comparatively cheap in price.

10. Direct dyes are used for cheap goods for local market.