Application of reactive dyes to wool

Presented by :
GOVIND CHINTARAM
BISSOONAUTH RISHTA

 To analyse the effect of reactive dyes on
Wool
 To observe the dye left in the bath at the
end of dyeing.
 To observe the amount of dye coming out
during after treatment

 Wool can be dyed with non mets dyes , mordant
dyes, pre met dyes, acid dyes and reactive dyes,
our practical has been based on the reactive dyes.

 wool is positively charge while the dye are
negatively charge and dye absorption takes
place in in the positive sites of the fiber. wool
dyeing is done under an acidic condition.

 Reaction to alkalis:
 Wool is quickly damaged by strong alkalis.
 Reaction to acids:
 1. Wool is damaged by hot sulphuric acid.
 2. The fibre is not affected by other acids.
 Affinity for dyes:
 Wool fibre has high affinity for certain types
of dyes, i.e. Acid, reactive dyes, Basic dye

 Reactive Dyes„ Form a covalent bond
between the dye and fiber
 „ Simplify dyeing procedure
 ‰No oxidation is used
 „ Introduced to the market by ICI in 1956
 „ Show improved fastness properties
 ‰Great improvement for cellulosic fibers

Dyeing occurs in two stages: Exhaustion and Fixation
exhaustion occurs by normal physical forces of attraction
between dye and fibre.
Fixing involves the formation of the covalent bond between
the dye and the fibre.

 The dye is covalently bound to the fibre

 High Fixation;
fibre tippiness -All anionic dyes on wool exhibit uneven strike which
can result in tippiness
With reactive dyes, if covalent attachment at tips occurs before
boiling.

A sample of wool fiber was used
 Wool was scoured
 Mass of sample : 3g

 Reactive dye : Lanasol 2% O.M.F
 Glauber Salt: 0.5%
 Acetic Acid: 2.0%
 Ammonium Sulphate

Liquor Ratio = 50:1

Vol of dye = 2 *3 = 6 ml
 Vol of Ammonium Sulphate = 6ml
 Vol of Glauber salt =3ml
 Acetic Acid = 6 ml
 Vol of Bath = 50 *3 = 150 ml
 Water = 150 – 6- 6- 3 – 6 = 129 ml

Continue dyeing for 60mins Drop the bath

60’
100oC

A:
20’
1. Ammonium sulphate,
10’ 2. Acetic acid,
3. Glauber’s Salt,
4. Under pH 4.5-5.0.

A B B: Dye

After Treatment
Washing off:
1. Hot rinse 70-80 oC for 5-10 mins
2. Treat with Ammonia Solution(pH 9-10) at 80oC for 20mins
3. Hot Rinse at 70oC for 5mins
4. Rinse under tap.

An alkaline treatment is important in achieving
excellent wet fastness properties with
reactive dyes on wool.

Wool was treated with Ammonia Solution
( pH 9 – 10) at 80oC for 20 minutes

Then hot rinse was done at 70 oC for 5 minutes.

To be effective the after treatment has to
remove most of the dye that is not
covalently bonded to the substrate.

 The amount of dye left in the bath at the end of the
dyeing:
 It was observed with naked eyes that comparing to the
initial concentrated solution before dyeing , the amount
to dye left in the beaker after dyeing is very m few.
 We can derived approximately that 4% of dyes has been
left in the solution and 96% has been exhausted by the
fiber.

Solution before dyeing Dye left after dyeing

 As wool is positively charged and reactive dyes are
anionic, so there is a strong linkage which occur between
the positive fiber and negative dye and the substantively is
very high which facilities the exhaustion of the bath.
 The molecule of the fiber is covalently bond to that of the
dye, and this bond cannot be break down, so once the
dyes is migrated into the fiber under acidic conditions, the
maximum dyes is being taken up by the fiber retains inside
and the hydrolysed dyes remains into the bath itself, which
are the 4% estimated remaining dyes in the bath.
 While dyeing, the pH is kept under acidic conditions which
is (pH 4.5-5) and the dyes reacts more with the fiber and
 More dyes go into the fiber.

 The amount of dye coming out during washing
off:
 It was observed that during the after treatment, a little
dye was coming out from the wool fiber, approximately 1%
when observed with naked eyes.
 This proves that the dyeing was done properly as a good
wash fastness was observed.
 Also , it can be noted that the tip of the fibers have been
uniformly dyed. This means that the problem of tippiness
has not taken place.

 The dye left in the beaker during after
treatment are the few hydrolised dyes which
has more affinity for the solution rather than
the fiber.
 As ammonium sulphate is used, it is a
swelling agent,so it swells the fiber and all
dead dyes get out which are the remaining
dyes in the beaker after treatment.

Application of reactive dyes to wool

More Related Content

What's hot (20)

Viewers also liked (20)

Similar to Application of reactive dyes to wool (20)

Recently uploaded (20)

Application of reactive dyes to wool

Editor's Notes