Direct Dye:
Direct dye is a dye used in a process in which dye molecules are attracted by physical forces at the molecular level to the textile. The amount of this attraction is known as "substantivity": the higher the substantivity the greater the attraction of the dye for the fiber. So it is called substantive dye.
DIRECT
DYE
|
|
MECHANISM
|
Hydrogen
Bonding.
Wander
Wall’s Forces between Fiber Surface and Dye Molecule.
Larger
Molecule Size.
|
STRUCTURE
|
 |
SOLUBILITY
|
Soluble
in Water.
Good
Affinity.
Polar
Nature.
|
CHARGEABILITY
|
Carry
Negative Charge.
Discharge
by Adding Salts,
i.e.
Na2SO4 , CuSO3
|
SUBSTANTIVITY
|
Moderate
Substantivity for the Fiber because Larger Size of Molecule.
pH Range:
10 - 11
|
FASTNESS PROPERTIES
|
Washing :
Weak
Rubbing
: Poor
Lightening : Good
Chemical : Poor
Perspiration : Average
|
APPLIANCES
|
They
are Applicable on Cellulosic and Proteinic Fibers;
i.e.
Viscose, Silk.
|
COLOUR RANGE
|
Large
Range of Colors.
Dull
and Darker Shades.
All
Colors are Achievable.
|
ENVIRONMENT BEHAVIOUR
|
Non-Environmental
Friendly.
Carcinogenic
Dye.
|
COST
|
U.S:
1.5 – 5 $/Kg
Cheap
|
