Definition: The term
‘scouring’ applies to the removal of impurities such as oils, was, gums,
soluble impurities and sold dirt commonly found in textile material and produce
a hydrophilic and clean cloth.
General
equation of Scouring:
Oil + Caustic Soda =Soap + Glycerol.
Scouring
Process
There are two
types of Textile Scouring Process –
1. Conventional
scouring process:
a .Kier boiling
(discontinuous) scouring.
b. Scouring in J
or L box (continuous).
c. Exhaust method
2. Special scouring process:
a. Solvent scouring
process.
b. Vapor lock
scouring process.
General recipe for scouring Kier boiler process
a.Alkali
(NaOH) - 2 to 5 gm per litr
b.Soda ash - x gm per litre to adjust PH
(PH required for scouring is 10.5).
c.Wetting agent
- 1 gm per litre.
d.Sequestering
agent - 1 gm per litre.
e. Detergent - 1
to 2 gm per litre.
f. Temperature -
100 to 1250c.
g.Time - 6 hours
(close vessel) and 8 hours (open vessel)
h. M : L - 1 : 10
i. N.B. :Water
level should keep 6 to 8” above the fabric.
The change occurring
of cotton fibers during scouring
Functions of scouring ingredients
Special Scouring Process
Solvent Scouring:
Solvent scouring is
the treatments of fabrics in organic solvent medium to remove impurities such
as lubricating oils and spin finishes. Certain organic solvents will readily
dissolve oils fats and waxes and these solvents can be used to purify textiles.
Removal of impurities by dissolution is called Extraction.
Advantages with solvents
a.Good solvents
for cotton wax
b. Removal of wax
at room temperature
c.Due to low
specific heat and much lower heat of evaporation than water, removal of solvent
from fabric was economically much more favorable.
d.Chlorinated
solvents are non flammable.
Differentiate
between alkaline and solvent scouring.
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