Application of Reactive dyes to other fibres
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| Application of Reactive dyes on silk fibre |
(1) Reactive dyes on Silk fibres -
As with wool or cellulosic fibres, reactive dyes can also produce covalent, extremely washable bonds with silk fibres. Reactive dyes with the following structural characteristics are favoured.
Mechanism of dyeing silk with reactive dyes -
The reactions between the diflurochloropyrimidine type and a lysine side chain (left) and a thyroxine side chain (right) silk fibroin molecules are shown below.
Reactions
Reactive dyes can be applied to silk in two ways -
(1) Exhaust method
(2)Cold pad batch method
Explanation-
(1) Exhaust method -
Reactive dyes are often applied to silk in two phases that are the same as those used for dyeing Cellulosic fibre with reactive dyes.
Phase 1 -
In this phase, the silk is dyed in an exceeding dye bath, the temperature of which is raised from 30 to 60°C over 20 to 40 minutes and to which 20 to 60 GPL Glauber's salt is added the precise quantity counting on the depth of shade being dyed.
As for cellulosic fibres, the salt is added in two portions during the heating phase (levelling phase) Phase 2 -
In this phase, fixation of the dyes takes place by the addition to the dye bath of two to five GPL saleratus in two portions while dyeing for 30 to an hour so cooling the dye bath.
Mostly reactive dyes belonging to the di Fluro chloro pyrimidine type are applied by this method at dyeing temperatures of 60 to 70°C.
The dyeing programme is as shown in the figure below-
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| Dyeing programme for reactive dyes on silk |
(2) Cold pad Batch method -
The fabric is padded with the following solution and batched
Recipe | Quantity |
Dye | X% |
Urea | 50 to 100 gpl |
Sodium bicarbonate | 10 to 20 gpl |
Wetting agents | 1 to 2 GPL |
The bath is then kept for twenty-four hours at 20 to 25°C The mechanism and procedures for dyeing silk are identical to those for wool.
Silk is degraded when exposed to light but, the reactive dyes resist the photochemical degradation. The dye structure is liable for this and hence Bifunctional reactive dyes are suitable for dyeing silk.
(2) Reactive dyes on Nylon -
The reactive range of dyes combines the benefits of the disperse and also the anionic dyes.
Their absorption by the fibre Therefore could be a physical process, conforming essentially to a partition of a solute between two immiscible phases. They do, however, contain within their molecule a bunch of polyamides.
Thus, under faintly acid conditions absorption is relatively uniform and barrenness is avoided.
When the dye bath is formed in Alkaline a chemical action takes place between the fibre and also the dye thus giving a degree of wet fastness comparable to that of Nylon The method of application is to line the dye bath at 40°C with the dyestuff and a couple of parts per 1000 parts of 30% ethanoic acid and 1 a part of a non-Ionic surface-active compound.
The temperature is raised slowly from 85 to 100°C and dyeing is sustained at this temperature for half-hour.
The pH is maintained at 3.5 to 4 by the addition of a little amount of ethanoic acid. At the tip of half-hour, 2.5 to three parts per 1000 parts of salt are added to bring the pH between 10 to 10.5 and Fixation is disbursed at the boil for a further hour.
When dyeing is complete the products are rinsed and also the heavier shades soaped. The washing fastness is of the order of 5.
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| Dyeing silk/wool in the weakly Acidic region |
Questions -
- What is the Application of Reactive dyes on silk fibres?
- What is the Application of Reactive dyes on nylon fibres?
- With which two methods Reactive dyes can be applied to silk fibres?
- Describe the Mechanism of dyeing silk with 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,
(Reactive dyes on wool and silk blend with their application)
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)
