A) According to chemical classification:
1)Azo derivatives:
a) Monoazo:
Example : Diazoraine scarlet 5B
(C.I. Direct Red 14)
b) Di-azo:
Example : Congo Red ( C.I. Direct Red 28)
c) Tri-azo:
Example : Congo Brown R ( C.I. Direct Brown
44)
2) Stilbene derivativesExample : Chrysophenine G ( C.I.
Direct Yellow 12 )
3) Thiazol derivatives:
Example : Premuline
4) Triphenodioxazine derivatives:
Example : C.I. Direct Blue 106
5) Phthalocyanine derivatives :
Example : Durazole blue 8G (C.I. Direct Blue 86)
B) Classification of direct dye according to application:
1) Class-A(Self leveling dye)
i.
Dye migrate well
ii.
High leveling power
iii.
They may dye unevenly at first but further
boiling will bring about even distribution.
2) Class-B(Salt controllable dye)
i.
Dyes of poor leveling power
ii.
ye exhaustion must be brought about by
controlled salt addition.
iii.
If these dyes are not taken up uniformly in the
initial stages, it is extremely difficult to correct the unlevelness
3) Class-C(Temperature controllable dye)
i.
Dyes are not self leveling.
ii.
Highly sensitive to salt.
iii.
The exhaustion of this dye is controlled by
temperature.