Bifunctional systems -
More recently, reactive dyes with bifunctional functionality and low salt content were created to enhance dye fixing and lessen environmental issues.
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| Reactive dyes fabric |
(A) Homo Bifunctional Reactive Dye Concept:
For exhaust dyeing, the concept of dyes with two reactive systems of identical type was developed.
These dyes have higher substantivity and better exhaustion and fixation values than mono-functional dyes.
The chromophores are often stable to combinations of sunshine and moisture or leftover peroxyl detergent, and therefore the dye-to-fibre bond is stable to mild acid and alkalis and oxidising agents.
The figure depicts the structural representation of a homo bi-functional reactive dye for Procion HE and H-EXL dyes.
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| Procion H-E and Procion H-EXL dyes |
(B) Hetero-bifunctional reactive dyes -
Bifunctional dyes with a mixed Reactive system within the dye molecule use the benefits of both the triazine and vinyl Sulphone system i.e higher Affinity of triazine and lower Affinity thanks to the vinyl Sulphone.
The triazine groups (higher reactivity) react with the fibre faster and this is often followed by the reaction of vinyl Sulphone (medium reactivity) which is slower in forming a stable dye fibre bond.
A diagrammatic representation of this sort of dye is shown in i.e sumifix supra dye.
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| Sumifix Supra dye |
The above type system also includes the reactive ME family of dyes, which have a medium substantivity and excellent migration.
Improved fixation is provided by the presence of two reactive groups within the molecule. When the temperature reaches about 60 °C, they generate level dyeing.
Questions -
- What are the bifunctional systems of reactive dyes?
- Explain Homo Bifunctional Reactive Dye Concept.
- Explain Hetero-bifunctional reactive dyes.
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)
