Fluorescent
Whitening Agent for cellulose fibbers at low temperature by padding or
exhaustion methods.
General
Properties
Form:
Yellow powder, on-hygroscopic
Chemical Constitution: Stilbene
Disulphonic acid adrivative
Ionic Properties: Anionic
pH of 1% Solution: About 9.0
Solubility: Clear, Colorless
Solution in boiling water: 70 g/1
In cooled liquor - 25 g/1.
Stock Solution: Upto 25 g/1 maximum and is
sensitive to light
Storage: In dark air tight container can be
applied within pH 8-11.
Special
Features
- Brilliant neutral white effects
- Very good stability in hydrogen peroxide bleach
baths
- Good compatibility with finishing agents
- Good wet fastness
- Moderate fastness to chlorine
- Good light fastness can be used in bleaching:
- Dyeing
- Finishing
- Printing and discharge pastes gives reddish
white shade.
With
Glauber's salt addition exhausts excellent effect on all cellulose
fibbers.
Exhaustion depends on the electrolyte content of
the bath.
Excellent leveling when applied in bleached bath
or at temperature 60 - 90C with no salt. Yield of optical whitener is
reduced.
Better affinity for cotton than viscose.
Water hardness caused quicker and complete
exhaustion of the bath and does not impair the white effect.
Iron and copper have adverse effect on the
whiteness.
Non-ionic softener has the least effect on
whitened goods.
Cationic products impair the whiteness and to
offset their action, more optical whitener is added.
Application
Dissolving
Varahi
White BVN is dissolved by adding 5-10 times its weight of hot,
preferably boiling water and if necessary boiling further. Stock
Stripping can be carried out by treating in a cold bath containing:
0.25-0.5% Potassium permanganate 0.5% Sulfuric acid for 20 minutes. The
goods are then treated with Cellulose materials can be whitened with
Varahi White BVN at all stages of manufacturing either by exhaust or by
padding method.
Stripping
Solutions
are sensitive to light and must be stored away from light 2-3% Sodium
bisulphite 0.5% sulfuric acid at 40 C, followed by neutralization and
rinsing.
An after treatment with light hydrogen peroxide
is recommended to restore the whiteness and avoid subsequent yellowing.
Typical Recipe
Varahi White BVN
Varahi White BVN
Glauber's salt
|
Exhaust
Method
0.05-1.0%
0.05-1.0%
2-5 g/1
|
Padding
Method
0.1 - 3.5 g/1
0.2 - 3.5 g/1
--
|
|
pH
(adjusted, if
necessary, with
ammonia or soda ash)
Temperature
Time
Softening can be carried out in final rinsing
bath by treating with 0.5-3% Avivan SFC
|
8-11
|
8-11
|
20-40
C
|
20-40
C
|
20
min.
|
---
|
|
hydrogen
peroxide
|
very
good
|
Sodium
chlorite
|
Poor
|
Chlorine
pH 11 (cold)
|
Moderate
|
Alkali
|
Very
good
|
Fastness
Properties Light
|
3-4
|
Washing:
Test 1 (40C)
|
5
|
Washing:
Test 2 (40C)
|
5
|
Washing:
Test 3 (60C)
|
3-4
|
Chlorine
|
2-3
|
Perspiration
|
4-5
|
Pleating
|
3-4
|
Methods of Application
Exhaustion (10-30 : 1)
Varahi White BVN
|
%
|
0.05 - 1.0
|
Glauber's Salt
Cale
|
g/1
|
1-5
|
Temperature
|
C
|
20-40
|
Optimum pH
(adjusted if necessary with
ammonia or soda)
|
pH
|
8-11
|
Time
|
Min.
|
20
|
Padding
|
VArahi White BVN
(No Glauber's salt)
|
g/1
C
|
0.2-3.5
20-40
|
Sleach Bath
|
Hydrogen
Peroxide bleach
Particularly good leveling
Varahi White BVN
Temperature as for bleeching
Conditions
|
%
|
0.05-1.0
|
Dyebath
|
Varahi White BVN
Anionic and non-ionic auxiliaries
have no adverse effect
|
%
|
0.05-0.6
|
Printing And Discharge
|
Varahi White BVN
pH
|
g/kg.
PH
|
1-2
over 7
|
Washing
|
Varahi White BVN
|
%
|
0.05-1.0
|
Resistance
|
Varahi White BVN
in the bath
Hydrogen peroxide
Sodium chlorite
Chlorine pH 11 (cold)
Alkali
|
very good
Poor
Moderate
Very good
|
|
|
