Introduction of disperse dyes
Disperse dyes are pigments with very low water solubility and are scattered finely. the scale of dispersed dye particles is within the range of 0.51 micrometres.
The fine aqueous dispersion is employed to use disperse colours.
The best fibres that distribute colour colours are nylon, polyester, acrylic, and cellulose.
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| Disperse dye chemical structures |
Chemically speaking, the dispersed dyes comprise various chemical categories, including azo, anthraquinone, methylene, and diphenylamine.
The dyes typically contain -OH, -NO, -CN, halogen, and amine groups; however, polar groups are never present.
The figure following depicts the chemical structures of two dispersion dyes.
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| Disperse dye |
Properties of Disperse dyes:
2. The absence of polar groups in dispersed dye molecules is an attribute. they're not easily soluble in water because of this. Nonionic.
3. the sunshine fastness of textiles dyed with dispersed dyes ranges from fair to good. the sunshine fastness rating is usually 4-5.
4. the common wash fastness for textiles dispersed dyed is 3, which is sweet to excellent. this is often caused partly by the dye's insolubility and non-part by the fibres' hydrophobic properties, to which they're often applied.
5. However, a number of the dispersed dyes are sensitive to nitrogenous fumes within the air, particularly air that has been contaminated by car fumes.
6. Disperse dyes have the flexibility to undergo sublimation, that is, they'll be vaporised without significant change in their colour. A stable electron configuration is a reason behind their capacity to sublime. Transfer printing makes use of this characteristic to its advantage.
7. Disperse dyed or printed textiles may lose colour if they're overly hot pressed or ironed.
8. The dyes have small molecules.
9. they are available in powder, liquid, and micro-dispersed granule form.
Classification of Disperse Dyes:
Group 1 | Group 2 | Group 3 | Group 4 |
Dyes possess excellent covering powder but, sublimation Fastness | Dyes possess good covering powder and moderate sublimation Fastness | Dyes possessing moderate covering powder and suitable sublimation Fastness | Dyes possess little ability to cover irregularities but have excellent sublimation Fastness |
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| Basic reaction mechanism |
Auxiliaries used in polyester dyeing:
(A) Dispersing agent | (B) Levelling agents |
(i)It reduces the size of the dye | (i). Non-ionic levelling agents retard the rate of dyeing. (iii) They also help avoid oligomer deposition on the fibre surface. |
(C ) Antifoaming agents | (D) Wetting agents | (E) pH and redox buffers |
Antifoaming agents are used in a dispersed dye bath to control the foam as excess foaming gives specky dyeings. | A small quantity of the wetting agent in the dye bath facilitates the dye liquor to be absorbed uniformly and quickly. | These agents protect the dyes from degradation in a high-temperature bath. |
Questions -
- What is the disperse dye? and how is it applied?
- What are the types of disperse dye?
- What are the properties of disperse dye?
References
Disperse dye additives. (n.d.). Borregaard.com. from https://www.borregaard.com/markets/dyestuffs/applications/disperse-dyes/
Dyeing polyester with disperse dye. (n.d.). Pburch.net. from http://www.pburch.net/dyeing/dispersedye.shtml
Gurr, E. (1971). DISPERSE DYES. In Synthetic Dyes in Biology, Medicine and Chemistry (pp. 691–702). Elsevier.
Holland, A. (n.d.). Disperse Dye for dyeing and printing polyester and sythetic fabrics. Georgeweil.com. from https://www.georgeweil.com/blog/disperse-dyes-for-dyeing-and-printing/
Transfer/disperse dyes - how to. (n.d.). Vycombe-arts.co.uk. from https://www.vycombe-arts.co.uk/transferdyes.html
Wypych, G. (2013). Weathering of compounded products. In Handbook of Material Weathering (pp. 581–717). Elsevier.
(N.d.). Textilelearner.net. from https://textilelearner.net/disperse-dyes-dyeing-and-printing-method/
Continue reading,
Part 2 Method of carrier Dyeing of Disperse dyes
Part 3 Method of HTHP Dyeing of Disperse dyes
Part 4 Other methods for disperse dyeing
