Reactive dye Systems
The important reactive system can be classified into two categories depending on the mechanism of formation of the dye fibre bond.
(II) Classification on basis of functional groups.
(Classification of reactive dyes can also be categorised as below method.
1. Classification of Reactive dyes
2. Reactive Systems classification
3. Chemistry of Reactive dyes and classification)
(I) Classification of the reactive system on the basis of Mechanism:
The reactive system is a difference in its reaction mechanism of Nucleophilic addition and Nucleophilic substitution hence, based on the mechanism of reaction or nucleophilic addition and substitution are -(A) Tri any type ring system.
(B) Beta Sulphatoethyl Sulphone type.
(A) Tri azinyl type ring system | (B) Beta Sulphatoethyl Sulphone type |
(1)These dyes react with cellulose by a process of nucleophilic substitution. | (1)These dyes react with Cellulose by the mechanism of nucleophilic addition |
(2)Two types of reactions- (a) Esterification(-O-Cell) (b) Hydrolysis(-OH) | (2)Two types of reactions- (a) Esterification(-O-Cell) (b) Hydrolysis(-OH) |
(3)Dyes such as Procion(ICI),Drimarene(Cla riant),Levafix E(Bayer) and Cibacron(Indo Swiss) etc fall in this group of reactive dyes | (3)The Remazol dyes(dye star),Levafix dyes(Bayer) & Promazin dyes(BASF) etc come under this group of reactive dyes |
(II) classification of the reactive system on the basis of the number of functional groups:
This is basically on the number of functional groups in the structure as well as based on the reactive system, reactive dyes can be further classified as follows :
(B) Bifunctional reactive dyes-these are further classified as homo Bifunctional and hetero Bifunctional dyes as in the below chart.
(C) Multi-functional reactive dyes.
(A) Mono functional reactive dyes-
These dyes are characterised by the presence of reactive groups(one or two reactive species) at individual locations within the dye molecule.
All the reactive dyes developed during the first stages of development were monofunctional reactive dyes.
Typical samples of this type are dyes having mono-chloro or dichloro triazine or vinyl Sulphone reactive groups. although di chloro triazine dyes are considered mono-functional reactive dyes.
(B) Bifunctional reactive dyes -
These dyes are introduced recently to the reactive dye range.
They are characterised by the presence of two reactive groups of the same type(mono or di chloro triazine) or two differing types (mono chloro triazine and vinyl Sulphone) at two different locations within the dye molecule.
Bifunctional dyes are divided into two types
(a) Homo Bifunctional dyes - These are having two reactive systems of the same type(triazine vinyl Sulphone).
(b) Hetero Bifunctional dyes -These are having two reactive systems of the Mixed type(triazine vinyl Sulphone).
The various Bifunctional combination that can be formed are listed below-
Bifunctional Combination | Homo or hetro | |
MCT/MCT | Monochlorotriazine/mon ochlorotriazine | Homo Bifunctional |
VS/VS | Vinyl Sulphone/Vinyl Sulphone | Homo Bifunctional |
MCT/VS | Monochlorotriazine/Vinyl Sulphone | Hetero Bifunctional |
FT/VS | Fluro Triazine/Vinyl Sulphone | Hetero- bifunctional |
FCP/VS | Fluoro chloro pyrimidine/Vinyl Sulphone | Hetero- bifunctional |
These dyes have very High exhaustion resulting in high fixation and better colour yield. Due to the high exhaustion and fixation, the quantity of dye within the dye bath further as that off from fabric during washing and Soaping is tiny.
The extent of pollution thanks to effluent discharge is also low. This category of reactive dye has become extremely popular for exhaust dyeing applications.
The high exhaustion of those dyes is due to the high relative molecular mass of the dye, similar in range to its direct dyes.
The high fixation is because of the presence of two groups which may react independently with cellulose with the formation of a cross-link.
The chronological development of reactive dyes and also the reactive systems are shown in the tables.
Questions -
- Give classification of reactive dyes on basis of Mechanism.
- Give Classification of reactive dyes on basis of functional groups.
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
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/
(N.d.). Textilelearner.net. from https://textilelearner.net/reactive-dyes-classification-dyeing-mechanism/
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)
