|
|
Direct Dyes are following groups:-
(a) Non - Benzidine and Sunfast Direct Dyes (Shade Card)
(b) Direct Dyes (Shade Card) |

|
Sunfast And Non Benzidine Direct Dyes
Direct
Dyes are used in wide range of dyeing applications such as on Cotton,
Silk and Viscose Fabrics. Direct dyes are Famous for their easy
application, leveling property, good brightness and fastness. These
dyes can be safely applied on Textiles and Leather.
PRE - TREATMENT
Good
pre-treatment is essential if satisfactory dyeing is to be obtained. To
get better depth and fair brightness, Grey Fabrics must be free from
impurities like sizing materials and spinning oil by boiling the Grey
with alkline or some times bleaching also carried out in case of pale
shades.
METHOD OF DYEING
(1) DISSOLVING THE DYESTUFF
The
dyestuff is pasted with cold water and dissolved by pouring 50 to 100
times its weight of Boiling water while stirring. The solution may be
boiled to ensure complete dissolution. For Certain dyes, which are dyes
from and alkline dye bath, it is preferable to add half its weight of
soda ash while pasting with water.
(2) YARN DYEING
Set
the Dye Bath at 50°-60° C temperature with dyes solution, salt and soda
ash. Run for 15 Minutes. Gradually raise Temperature to 90°-95° C. Run
for 30 to 45 minutes. In order to Overcome un level dyeing salt may be
added in installments after about 15 minutes of initial dyeing prior to
raising the dye bath temperature.
In
the case of dyestuff which possess maximum affinity at temperature
below boil, it is preferable to start dyeing at boil, dye for 15 to 20
minutes and then add salt in two installments to exhaust the bath abd
continue dyeing in a cooling bath (60° c) for 15 to 20 minutes.
chrysophinine
(D. PILA), Blue 2B(banzi blue), Green B(Bottle Green) Borduax
(D.Chocklet)and Yellow 5GLL can be dyed in this manner.
JIGGER DYEING
The dyeing on the Jigger is carried out as follows:- First End : 1/2 quantity of Dyes solution, soda ash and 1/4 quantity of Salt at room Temperature. Second End : 1/2 quantity of Dyes solution, 1/4 quantity of Salt at 60°)c, raised to 80°c. Third End : 1/4 quantity of Salt. Fourth End : 1/4 quantity of Salt.
The
temperature is raised to raised to boil and four ends are given at
boil. Finally the dye-liquor is Drained and further two ends are given
in cold water.
AFTER TREATMENT
Fastness to wet treatments can be improved by after treatment with 1-2% Cationic Dye Fixing Agents at 40-50° c for minutes. In case of some selected dyes, light fastness can be improved by after treatment with:- 1-2% Copper Sulphate 1-2% Actic (30%) at 80° c Temparature.
Benzidine Direct Dyes |