What is bifunctional reactive dye?
What is bifunctional reactive dye?
Bifunctional reactive dyes are coloured compounds that have more than one reactive moiety per molecule or groups capable of forming covalent bonds between carbon atom of the dye ions or molecules and functional groups of the substrate. This is due to effective penetration and efficient dye fixation with cotton fabrics.
What is meant by reactive nature of dye?
Reactive dyes form a new chemical compound when they come into contact with a fiber molecule. Reactive dyes are applied either from a solution with high pH or from neutral solutions that are later alkalized through a separate process. Sometimes different shades are brought out by applying heat to the dyed textile.
What are reactive colors?
In a reactive dye, a chromophore (an atom or group whose presence is responsible for the colour of a compound) contains a substituent that reacts with the substrate. Reactive dyes have good fastness properties owing to the covalent bonding that occurs during dyeing.
What is exhaustion in reactive dyeing?
Exhaustion: There are two types of exhaustion that relate to the application of reactive dyes: primary exhaustion and secondary exhaustion. Primary exhaustion occurs before the addition of the alkali, while secondary exhaustion takes place after the addition of the alkali.
Why do dyes have different Colour strengths between batches?
Why do dyes have different colour strengths between batches? Dye manufacturers mix the dyes with other compounds which are not colorants to give them various properties. The proportions that are added are not always identical from batch to batch.
How will you explain direct and reactive dyes?
Reactive dyes are usually used when dyeing dark colors. Any color that washes out is “residual” dye that was not absorbed by the yarn; it is not “bleeding.” Direct Dye is a dye used in a process in which dye molecules are attracted by physical forces at the molecular level to the yarn.
Why is reactive dye so called?
The term reactive signifies that the dyes react rapidly with an inert fiber like cotton and produces co-valent bond formation with an excellent color fastness. So, this dye stuff is called reactive dye.
Why is polyester dye dispersed?
Disperse dyes are generally non-ionic synthetics with saving dissolvability in water that can hold similarly and better substantively for hydrophobic fibers, for example, nylon and polyester [1,2,3,4,5,6].
What are the requirements for selecting compatible dyes?
Compatible dyes are dyes which build up on shade in that they increase in depth as the dyeing progresses to one single shade. Incompatible dye mixtures build up off shade making shade matching very difficult. The dye supplier should be able to specify which dyes in his range are compatible.
How does quality of dye decrease?
Yes, the quality of dyes can decrease in two main ways. Firstly, dyes can also absorb water which makes them heavier, so when they are weighted out for a recipe, less colorant is actually weighted out than needed. Secondly, dyes can react with water in the atmosphere and hydrolyze.
What are the different types of reactive dyes?
Types of Reactive Dyes. Bifunctional Dyes – Dyestuffs containing two groups are known as bifunctional dyestuffs. These reactive dyes are designed in such a manner to have the capacity to react with the fibre in more than a single way. Vinylsulphone Dye (VS) – Vinylsulphone Dyes are moderately reactive.
Which is more reactive vinylsulphone or monochlorotriazine dye?
Monochlorotriazine Dye (MCT) – Normally these dyes are less reactive than vinylsulphone dyes. Reaction can take place in more energetic reaction conditions. That is typically 800 degreeC and pH value of 10.5, are essential for a proper fixation on cellulosic fibres.
Can a reactive dye be used on nylon?
Reactive dyes can also be applied on wool and nylon; in the latter case they are applied under weakly acidic conditions. Reactive dyes have a low utilization degree compared to other types of dyestuff, since the functional group also bonds to water, creating hydrolysis.
Which is Bifunctional dyes contain two groups?
Bifunctional Dyes – Dyestuffs containing two groups are known as bifunctional dyestuffs. These reactive dyes are designed in such a manner to have the capacity to react with the fibre in more than a single way. Vinylsulphone Dye (VS) – Vinylsulphone Dyes are moderately reactive.