After treatment of reactive dyes -
In the dyeing of certain deep shades or with inefficient Washing equipment difficulties may arise in clearing unfixed colours.
In these circumstances, it's advisable to convey counter-current Washing off treatment (cascading type).In addition to the same old Soaping treatment.
An after treatment with a cationic dye chemical compound of the kind used for direct dyeing.
These agents operate by electrostatic association with the sulfonic acid groups within the dye molecule and forman insoluble dye agent complex.
This is retained by the fibre during wet treatments at temperatures up to 60°C so that staining is greatly reduced.
When the most effective possible washing-off treatment has been given the dye-fixing after treatment is dispensed during a fresh bath of cold water and the temperature is then raised to the optimum level for the particular agent selected (50 to 60°C).
A final rinse isn't essential however, treatment with dye fixing agents should never be considered a substitute for a much more efficient washing-off Process.
Stripping of reactive dyes -
Partial stripping of dyed goods for rectification of any dyeing fault is also administrated by treatment of the products with 5 to 10 ml/l of glacial carboxylic acid at 80 to 90°C.
Formic acid (10 ml/l) is preferred for stripping reactive dyes from viscose goods. Stripping is sustained until the shade is reduced to the specified extent.
Through Soaping and washing is important to confirm the removal of stripping dyes.
Complete stripping of reactive dyes to a white is incredibly difficult but they'll be stripped to an extent suitable for redyeing either in the same shades or too dark shades.
The goods are treated at boil during a solution of 5 GPL sal soda for 20 to half-hour. The washing off and Soaping at the boil for 10 to fifteen minutes.
Fastness properties of reactive dyes -
Fastness properties of reactive dyed cellulosic fibres -(1) Lightfastness -
Exposure to light under low humidity doesn't affect light fastness, but under high humidity, there's a discount in light fastness, particularly in pale shades.
(2) Wash fastness -
Reactive dyes have superb wash fastness thanks to their Strong bond however, under cleanup conditions (chlorine) there's an impact on the bond.
(3) Catalytic fading -
Some reactive dye mixtures have a bent to undergo catalytic fading.
(4) Phototropism -
When treated with cation active dye fixing agents such as Fixanol PN and specific crease-resisting finishes, some reactive dyes exhibit increased phototropism.
When the dyed material is exposed to harmful irradiation like ultraviolet light or when exposed to harsh sunshine, the shades typically turn violet or purple. When the light is normally restored, the shade gradually goes back to its original shade.
(5) Sensitivity to metals -
Metallic ions, in particular copper, can make dyes reactive.
A suitable metal sequestering agent should be employed in the presence of such metals, but take caution as any overuse results in a loss of colour.
(6) Storage of dyed material -
When not resin-finished, medium and heavy Procion brilliant red 2B on cotton has been observed to leave scars or stain nearby white material when kept in humid, acidic conditions.
The impact of rayon is far smaller. When added to the soap bath during the washing process, some amines such as ethylene diamine significantly reduce bleeding. But this process somewhat modifies the shade.
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| Fastness properties of reactive dyes |
Questions -
- What is the after-treatment of reactive dyes?
- What is the Stripping of reactive dyes?
- Describe the Fastness properties of 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)
