Reactive Dye

A Presentation on . . .
REACTIVE DYE

Prepared By : Mazadul Hasan Sheshir
MSc in Textile Engg - Butex 4th
Batch - Wet Processing Engineering
BSc in Textile Engg - SEU 13th
Batch - Wet Processing Technology
Email: mazadulhasan@yahoo.com
Blog : www. Textilelab.blogspot.com (visit)
Southeast University
Department Of Textile Engineering
I/A 251,252 Tejgaon Dhaka Bangladesh
Prepared By :
©right
Bangladesh University of Textiles
92 Shaheed Tajuddin Ahmed Avenue, Tejgaon,
Dhaka-1208, Bangladesh

Enhancing Our Presentation
We have feature for every step of the way
IntroIntro
ductiducti
on &on &
DiscuDiscu
ssionssion
ChemiChemi
stry &stry &
MechMech
anismanism
ApplicApplic
ationation
&&
PractiPracti
cesces

Introduction & Discussion
Definition, naming, history, characteristics, classification, trade name etc

Definition
• A dye, which is capable of reacting chemically
with a substrate to form a covalent dye
substrate linkage, is known as reactive dye.
• Here the dye contains a reactive group and
this reactive group makes covalent bond with
the fiber polymer and act as an integral part of
fiber.

Reaction
D-SO2-CH2-CH2-O SO3Na + HO- cell →
D-SO2-CH2-CH2-O-cell + NaHSO3
D-SO2-CH2-CH2-O SO3Na + NH2- wool →
D-SO2-CH2-CH2-NH-Wool + NaHSO3
Here, D = dye part.
Wool = wool polymer.
Cell = cellulosic polymer.

Reasons for so named
• Reactive dyes are so called because this is the
only type of dye, which has reactive group,
and that reactive group reacts chemically with
fiber polymer molecules and form covalent
bond.

Properties of reactive dye
1. Reactive dyes are cationic dyes, which are used for dyeing cellulose,
protein and polyamide fibres.
2. Reactive dyes are found in powder, liquid and print paste form.
3. During dyeing the reactive group of this dye forms covalent bond
with fibre polymer and becomes an integral parts of the fibre.
4. Reactive dyes are soluble in water.
5. They have very good light fastness with rating about 6.
6. Textile materials dyed with reactive dyes have very good wash
fastness with rating about 4-5 due to strong covalent bonds formed
between fibre polymer and reactive group of dye.
7. Reactive dye gives brighter shades and has moderate rubbing
fastness.
8. Dyeing method of reactive dyes is easy.
9. It requires less time and low temperature for dyeing.

History two chemists of ICI company (UK) named
Stephen and Rattee
invent a new dye in
1956
They were awarded gold medal of the
society of dyes and colorists for the year
1960
The first three reactive dyes were
PROCION YELLOWR,
PROCION BRILLIANT RED 2B
PROCION BLUE 3G

Reason of Popularity
• Ability to produce bright
shades of wide range.
• High leveling quality.
• Good washing fastness.
• Good light fastness.
• Simple dyeing method
therefore one stage dyeing.
• Low temperature dyeing
(below 1000
C)
• Lower cost, i.e. cheaper.

Classification
On the basis of reactive group:
1. Halogen derivatives
 Triazine group
 Pyridimine group
 Quinoxaline dyes
2. Activated vinyl compound
On the basis of temperature:
1.Hot Brand
2.Cold Brand
On the basis of reactivity:
1.Highly reactive
2.Moderate reactive
3.Lower reactive

Trade Name
Trade name Manufacturer Country
Procion I.C.I U.K
Cibacron Ciba Switzerland
Remazol Hoechst Germany
Levafix Bayer Germany
Reactone Geigy Switzerland
Primazin BASF Germany
Drimarine Sandoz Switzerland

Chemistry & Mechanism
Chemistry of Reactive group, assistant, mechanism etc.

Characteristics of reactive group of reactive dye:
• Reactive groups do not contribute to the color of dye. Chromogen group
imparts it.
• The reactivity of vinyl sulphone group is less than that of halogen group.
• If no of reactive group increases, binding also increases.
• Reactive dye absorb up to 90%.
• Molecular weight of reactive group 69-211gm/ mole.
• If the molecular weight of reactive group increases, reactivity increases.
• Chlorine imparts medium reactivity, but it is cheap.
• Reactivity of fluorine is the least and its rate hydrolysis is also less.
• Reactivity of vinyl sulphone group increases with increasing temperature
and pH.
• Sulphone group has more solubility but it is not stable.
• Generally low molecular weight dyes are of hot brand.
• Less affinity dyes are used for pad method.

Assistants used for dyeing with reactive dyes
• Salt:
 It neutralizes the electro negativity of fibre surface when immersed in
solution.
 It puts extra energy to push the dye inside the fibre polymer i.e. increase
absorption of dye.
• Alkali:
 to maintain proper pH in dye bath and thus to create alkaline condition.
 Alkali is used as a dye-fixing agent.
• Urea: It helps to get required shade of dye.
• Soaping:
 Extra color is removed from fibre surface. Thus washing fastness is
improved. Soaping increases the brightness and stability of the dye.

Dyeing mechanism of reactive dye
• Exhaustion of dye in presence of electrolyte or
dye absorption.
• Fixation under the influence of alkali.
• wash-off the unfixed dye from material
surface.

Application & Practices
Factors, Application methods, stripping, hydrolysis, faults & remedies

IMPORTANT FACTORS FOR DYEING CELLULOSIC FIBRE
1) pH of the dye bath
2) Amount of alkali
3) Dyeing temperature
4) Electrolyte concentration
5) Time of dyeing
6) Liquor ratio

Different methods of reactive dye application
• Pad-batch method.
• Pad batch processes are of two types-
– Pad (alkali)-batch (cold) process.
– Pad (alkali)-batch (warm or hot) process.
• Pad dry method
• Pad steam method.

Cold Pad Batch
Steps:
1) The fabric is first padded in a padding mangle with reactive dye in
presence of an alkali.
2) The padded fabric is rolled in a batch and the batches are wrapped by
polyethylene sheets and stored in wet condition for 1-24 hours at 200-
300C in a room.
3) During the storage period, the rolls may be kept slowly rotating to
prevent seepage of the dye liquor.
4) After storing time is finished fabric is washed in a rope washing
machine to remove the unfixed dye from fabric surface.

Stripping
Partial stripping:
Acetic acid: 5-10 parts
Water: 1000 parts
Or
Formic acid: 2.5 to 10 parts
With water: 1000 parts
Temperature: 70 - 100°C
Time: until desired shade is
obtained.
Full stripping:
Na-hypochlorite : 1%
at room temperature
Na-hydrosulpite: 1% at boil.
Time : 30 min
Stripping becomes necessary when uneven dyeing occurs. By stripping azo
group (--N=N--) from the dye is removed.

Hydrolysis of reactive dye
Reaction of dye with water is hydrolysis of reactive dye
1.Hydrolysis of halogen containing reactive dye,
D-R-Cl + H-OH →D-R-OH + H-Cl
1.Hydrolysis of activated vinyl compound containing dye,
D-F-CH2-CH2-OSO3H + H-OH →D-F- CH2-CH2-OH + H2SO4

Prevention of Hydrolysis
• As hydrolysis increases with increasing
temperature during dissolving and application
temperature should not be more than 40°C.
• Dye and alkali solution are prepared
separately and mixed just before using.
• Dye and alkali should not be kept for long
time after mixing.

Dyeing Faults
• Uneven Dyeing
• Batch to Batch Shade variation
• Patchy dyeing effect
• Roll to roll variation or Meter to Meter variation
• Crease mark
• Dye spot
• Wrinkle mark
• Softener Mark

Reactive Dye

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