Direct Dyes

THE DIRECT PATH TO COLOR

Direct dyes are so called because they are applied directly to the cellulosic fiber without the need for any mordant, the dyeing process is very simple and it is a purely physical process; When the fiber is immersed in the dye bath, the fabric acquires a negative character and the direct dye, which is anionic, binds to the surface and is fixed by means of a system of opposite electrical charges. Direct dyes have good light fastness but low fastness to wet processes.
QUIMIGEN S.A.C. provides very good quality direct dyes and high light fastness

DIRECT DYES ON COTTON
1.INTRODUCCION
We offers a wide range of DYCROMINE direct dyes for coloration cellulosic material. They are used for dyeing cotton, wool, silk viscose rayons, jute blends and union fabrics containing the cellulosic fiber using conventional equipment, for example becks, package dyeing machine winches, jigs and padding machines.

2.PREPARATION OF GOODS
It is necessary to remove all impurities from grey yarn or fabric to ensure level dyeing, good penetration of dyestuffs and maximum brightness of the shade. Size may be removed by boiling the goods in alkaline detergent solution. In case of bleached goods, it is advisable to wet the material with a suitable wetting agent, 0.75 g/l in hot and then it is rinsed in water.

3.DYEING METHODS
Two dyeing methods are recommended.

Dyeing Method No 1:
The dyebath is prepared using X% – Dyestuffs 0.5-2.0% – Soda ash and 5.0-3.0 % – Calcined Glauber’s salt. The dyeing is started at 50°C, the temperature is raised to 900 – 950°C. and the material is boilet for 45-60 minutes. The addition of salt should be made in gradual stages.

Dyeing Method No.2:
Same as method No. 1, but without addition of Soda ash. This method is generally used which is described as under.

A: X% Dycromine dye
B: 1-8 g/l Anhydrous Glauber’s Salt
C: 4-32 g/l Anhydrous Glauber’s Salt

. Set the dye bath at 40°C with required amount of water and dye.
. Run for 10 minutes and add anhydrous Glauber’s Salt (B)
. Enter the goods and run for 10 minutes.
. Raise the temperature to boil within 30 to 45 minutes.
. Add anhydrous Glouber’s Salt (C) and continue the dyeing for 30 minutes.
. Decrease the temperature to 80°C within 10 minutes and continue the dyeing for 15 minutes.
. Drain the dye bath at 70°C. Give two cold washes and dry.
. If required, treatment of cationic dye fixing agent may be given to improve the fastness properties

Note: High dye yield & the best reproducibility can only be achieved by a process-controlled cooling & holding phase at 80°C.
Shading: Cool to 70°C, add the shading dye, and raise the temperature to 90°C in 15 mins. & treat as usual. 4
ILLUSTRATION The shades shown in the shade card was prepared on unmercerised cotton fabric.