Reactive dyes
Reactive
dyes are a class of dye that forms a covalent bond with the fiber and is an integral part of the fiber. Cellulosic fibers like cotton, rayon, or flax are
usually used for these dyes, but polyamide, wool, silk, and acetate fibers can also
be dyed using reactive dyes.
Reactive
dyes are so-called because it is the only type of dye that has a reactive
group. This group reacts chemically to form covalent bonds with fiber polymer
molecules. This covalent bond is formed between the reactive group and the -OH
group of terminal cellulosic fibers and the polyamide and wool fibers of the
terminal -NH2 group. Examples are below-
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| Reactive Red 24 |
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| Reactive Blue 19 |
Characteristics of reactive dyes
i.
Reactive dyes are cationic dyes that are mainly used for dyeing cellulose,
protein, and polyamide fibers.
ii.
All kinds of shades are achieved from this dye.
iii.
It is available in powder, liquid, and print-paste forms.
iv.
These dyes are water-soluble.
v.
They have very good light fastness with a rating of 6, dyes have a very stable
electron configuration, and can withstand the corrosive effects of ultraviolet
rays.
vi.
Due to the strong covalent bond between a reactive group of fiber polymers and
dyes, it is very good to wash with a variety of colored textiles with a rating
of 4-5.
vii.
It gives bright shades and is moderately abrasive.
viii.
Responsive shades have a good sweat consistency with a rating of 4-5.
ix.
Textile materials dyed with reactive dyes have a very good wash fastness with a
rating of about 4-5 due to strong covalent bonds formed between the fiber polymer
and a reactive group of dye.
x.
It requires less time and a low temperature for dyeing.
xi.
It has a lower degree of use than other types of dyestuffs because the
functional group bonds to water, creating hydrolysis.
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