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
 |
| Factors affecting the results of reactive dyeing |
Explanation :
(A) Affinity of the dyes:
The molecular structure of a dye determines its affinity for fibre, therefore the dryer has little control over this aspect of dyeing except to settle on the dyes that are most suited to his or her unique dyeing procedure from among people who are offered.
Apart from the H-E dyes, which by getting two reactive centres to provide a high degree of fixation and so less hydrolyzed dye to be washed off, reactive dyes typically possess a comparatively low affinity for cellulose thanks to the challenges related to washing off hydrolyzed dye.
This causes the exhaustion of reactive dye to extend with a high affinity for cellulose resulting in efficient fixation.
A drawback with all other commercial reactive dyes presently marketed is that the proportion of dyestuff getting into activity during fixation rarely exceeds 70% and thus the dyed material requires vigorous Soaping and washing treatment In exhaust dyeing of rather higher affinity gives better colour yield especially when dyed at long liquor ratio and when the washing off Process could be a smaller amount critical.
In dyeing by continuous processes, however, dyes of lower Affinity have a plus as they're less susceptible to Tailing but are still efficiently fixed at the short liquor ratios involved in padding processes.
Then knowledge of the affinity of dyes is advantageous in selecting those most suited to a particular application process.
(B) Material to Liquor ratio (MLR) :
When determining exhaustion, the liquor ratio can have a big impact. Low-affinity reactive dyes could also be especially important in this regard.
Wider types of reactive dyes will be used more affordably when low liquor ratios are used, and in every case, this ends up in more efficient fixation by reducing wasteful hydrolysis within the dye bath.
Although the liquor ratio will be prepared using the available machinery, using packages dyeing machines instead of open becks is the only thanks to use reactive dyes on yarn.
Jig applications are more productive for piece dyeing than winch dyeing, and therefore the pad roll or pad batch approach is the foremost producer of all batch dyeing methods.
These advantages are more obvious with dyes that have low exhaustion in a long liquor ratio but with those of upper Affinity just like the reactive H-E dyes, the liquor ratio won't have a heavy effect on the Exhaustion of the dye bath.
(C) Concentration of electrolyte:
Electrolytes are utilised to extend the Exhaustion percentages within the commencement of dyeing because the reactive dyes behave like direct dyes.
Cellulose fibres acquire an electrical charge when submerged in water, indicating that their surface is anionic, as was mentioned earlier. Likewise anionic are reactive dyes.
So, when submerged in an exceedingly reactive dye bath, the fibre repels the dye molecules.
Now, when salt is added to the bathtub, like common salt or Glauber's salt, it first ionises to supply positive sodium ions and negative chloride or sulphate ions.
The sodium ions move towards the fibre and neutralise the negative surface charge.
The chloride or sulphate anions repel the dye anions within the dye bath and cause them to manoeuvre towards the fibre surface where they get adsorbed.
Further, since the sodium cations are attached to the fibre surface during the initial stages of dyeing they are too inclined to rush to the fibre and find adsorbed unevenly.
If this happens it's difficult to remobilise them and thru about evenness. It is for this reason that the salt is added slowly and in portions.
Sodium sulphate is milder in action compared with the compound because it liberates only half the quantity of sodium ions liberated by common salt considering equal quantities of the two salts.
Therefore for reactive dyes like Turquoise brilliant blue, which don't easily give leval shade the utilization of sulphate (Glauber's salt) is extremely recommended.
Questions -
- Which factors are affects the results of reactive dyeing?
- Describe the Affinity of the reactive dyes.
- Describe the Material to Liquor ratio (MLR) for the reactive dyeing process.
- Describe the Concentration of electrolytes 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)
