General Factors affecting the results of reactive dyeing:
Reactive dyeing is influenced by several elements, and better products will be produced if these factors are fully understood. Affected by the following factors is reactive dyeing.
(A) Affinity of the dyes
(B) Material to Liquor ratio (MLR)
(C) Concentration of electrolyte
(D) the pH of the dye bath
(E) Dyeing temperature and reactivity
(F) Time of the dyeing
(G) Nature of the fibre
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| Reactive dyeing process |
Explanation -
(D) the pH of the dye bath:
Reactive colours' ability to stick to cotton and viscose depends not only on the precise dyes used but also on the temperature and timing of the dying process.
With a rising temperature and longer drying times, the pH requirements for several colours decrease.
The best pH for cotton is between 10.8 and 11 at 20 to 25°C, while the best pH for viscose is between 10.3 and 25°C.
The best soda for cold brands uses sal soda, detergent builder (TSP), carbonate, and chemical compounds as alkalis in reactive dyeing. For the new brand, TSP or a mixture of bicarbonate of soda and soda ash(50:50) is preferred.
The removal of hydroxide after dyeing could also be a tedious process so its use within the dyeing of cotton with reactive dyes is somewhat restricted.
However, a mix of soda and hydroxide is additionally used for the fixation of reactive dyes on cellulosic fibres.
The amount of Alkali required for fixation depends on the reactive dye brand used the depth of shade and thus the liquor ratio of dyeing.
● Soda ash
● A combination of washing soda and hydroxide
● Trisodium phosphate
It is preferable for heavy material and rayon to use bicarbonate instead of soda because it ensures maximum colour yield and better levelness because of less Swelling.
(E) Dyeing temperature and reactivity:
Raising the dyeing temperature decreases Substantivity, which facilitates levelling before the addition of an alkali and, consequently, the washing off of unfixed dye at the top of the method.
Additionally, the dye's reactivity is crucial throughout this process.
As mentioned previously, cold brand dyes, which are extremely reactive, may be applied effectively at temperatures as low as.
On the opposite hand, hot brand dyes require a temperature of 80 to 100°C for fixation and are approximately 1000 times less reactive.
(a) Increasing the alkalinity of the dye bath(i.e increasing pH value )
(b) Raising the temperature
A raised dye bath temperature is usually needed to assist penetration and hence to urge level dyeing, however, a higher temperature increases the reactivity of the dye so there could also be a danger of getting unlevel dyeing, especially with the cold brand dyes; this successively requires further control of reactivity through a reduction in cold brand dyes; this, in turn, requires further control of reactivity through a reduction within the pH of the dye bath. Substantivity and reactivity are therefore manipulated together to manage the quality of Dyeing.
(F) Time of dyeing:
Two pieces of the dye are typically applied to the bathtub. There are two salt addition options.
In 20 to half-hour, exhaustion usually sets in. These don't represent any distinct benefits of extending the Exhaustion phase past a half-hour.
Following the addition of the alkali in two batches, the dyeing process was continued for an extra 30 to 90 minutes.
The length of dyeing depends on the intensity of the colour and also the dye's reactivity. Taking longer hours is critical for darker hues.
(G) Nature of the fibres:
There are noticeable variations in the level of fatigue produced by reactive dyes on various cellulosic fibres.
Cotton produces the worst tiredness and viscose the most effective, with mercerized cotton coming in third.
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| Impact on the reactive dyeing process |
Questions -
- Which factors are affects the results of reactive dyeing?
- Describe the pH of the reactive dye bath.
- Describe the Dyeing temperature and reactivity for the reactive dyeing process.
- Describe the Time of the reactive dyeing.
- Describe the Nature of the fibre for the reactive dyeing process.
References
Ahmed, S. (2014, September 29). Reactive dyes - classification. TextileTuts. https://textiletuts.com/reactive-dyes/
Chakraborty, J. N. (2010). Waste-water problem in textile industry. In Fundamentals and Practices in Colouration of Textiles (pp. 381–408). Elsevier.
Clark, M. (2011). Handbook of textile and industrial dyeing: Principles, processes and types of dyes (Matthew Clark, Ed.). Woodhead Publishing.
No title. (n.d.). Acs.org. from https://cen.acs.org/articles/96/i29/new-textile-dyeing-methods-make.html
Patwary, E. M. Z. (2012, February 18). Reactive dyes. Textile Fashion Study; Engr. Mohammad Zillane Patwary. https://textilefashionstudy.com/reactive-dyes-definition-classification-properties-and-influencing-factors/
Sayed, A. (n.d.). Why reactive dye is so called? Blogspot.com. from https://textileapex.blogspot.com/2013/11/reactive-dye.html
(N.d.). Textilelearner.net. from https://textilelearner.net/reactive-dyes-classification-dyeing-mechanism/
What are Reactive Dyes? Types of Reactive Dyes. (n.d.). Meghmaniglobal.com. from https://www.meghmaniglobal.com/what-are-reactive-dyes-types-of-reactive-dyes/
Continue reading,
Part 2 Classification of Reactive dyes
Part 3 The reaction of MCT and DCT of reactive dyes
Part 4 General Factors affecting the results of reactive dyeing
Part 5 Reactive dyeing method - DCT
Part 6 Bifunctional systems of reactive dyes
Part 7 Development of reactive dyes
Part 8 Reactive dyes on Silk and nylon with their application
Part 9 Industrial applications of reactive dyes
Part 10 After treatment of reactive dyes
Writer - Rushikesh Patil (Textile Engineer)
