Importance of fixing agent on the colour fastness of reactive dyestuff ...

Dyeing Printing Finishing
<strong>Importance</strong> <strong>of</strong> <strong>fixing</strong> <strong>agent</strong> on the colour fastness <strong>of</strong> reactive
dyestuff originated from various dye manufacturers
Sumon Mazumder 1 and Md. Mahbubul Haque 2
1 Daffodil International University, Dhaka, Bangladesh, sumon.te@daffodilvarsity.edu.bd
2 Daffodil International University, Dhaka, Bangladesh, drhaque@daffodilvarsity.edu.bd
Abstract: Reactive dyes are the dominant choice <strong>of</strong> colorants to produce colouring effect on cotton goods for some technical advantages.
Reactive dyes have a great usage due to having a wide color range and a greater color fastness rating. Most <strong>of</strong> the wet processing industries
are using reactive dyes on textiles for coloration purposes. Reactive dyes are the only class <strong>of</strong> dyes which make co-valent bond with
the fibre molecules, so the colour fastness characteristics become greater. After treatment is carried out in reactive dyeing to remove the
weakly bonded unfix dyes from the fibre substrate. However, <strong>fixing</strong> <strong>agent</strong> may be induced after reactive dyeing to improve the stability
<strong>of</strong> previously formed co-valent bond between dye and fibre molecules. The aim <strong>of</strong> this paper is to study the effects <strong>of</strong> <strong>fixing</strong> <strong>agent</strong> on
cotton fabric dyed with reactive dye. For the determination <strong>of</strong> these effects, Colour fastness properties and colour difference values have
been measured in case <strong>of</strong> dyed cotton material before and after using <strong>fixing</strong> <strong>agent</strong>.
Key words: co-valent bond, cross-linking <strong>agent</strong>, gossypium, beta-glucose, colour fastness.
1. Introduction
Cotton is the purest form <strong>of</strong> cellulose found in nature, is the
seed hair <strong>of</strong> plants <strong>of</strong> the genus gossypium. [1] Cellulose is the
most common organic compound on Earth. About 33 percent <strong>of</strong>
all plant matter is cellulose (the cellulose content <strong>of</strong> cotton is 90
percent and that <strong>of</strong> wood is 50 percent). [2] Cellulose is an organic
compound with the formula (C 6 H 10 O 5 )n, a polysaccharide consisting
<strong>of</strong> a linear chain <strong>of</strong> several hundred to over ten thousand
β(1→4) linked D-glucose units. [3]
Figure 1: Polysaccharide consisting <strong>of</strong> β (1 4) linked D-glucose units.
Cellulose monomers (beta-glucose) are linked together
through 1, 4 glycosidic bonds. Cellulose is a straight chain and no
coiling occurs. Of the three hydroxyl groups on the cellulose
rings, two are secondary, and one is a primary. Most reactions
with cellulose occur at the primary hydroxyl group. Cotton naturally
contains oils, fats, waxes, minerals, leafy matters, motes etc
as impurities that interfere in dyeing and finishing.
The process <strong>of</strong> removing these impurities from cotton is called
as scouring. [4] Usually cotton fibres are <strong>of</strong>f-white in colour due
to having colour bodies with it and the process <strong>of</strong> destruction
these colour bodies from fibres is known as bleaching. [5] Before
cotton fibre coloration with reactive dyes, scouring and bleaching
process is essential to perform for producing even colour on fibre
substrate.
Reactive dyes have water solubility and can posses various
reactive groups which during the process <strong>of</strong> dyeing (during
dyeing <strong>of</strong> cellulosic material with fibre-reactive dyes) react chemically
with the fibre substrate to form a co-valent bond in presence
<strong>of</strong> alkali so that it becomes a part <strong>of</strong> the fibre itself. [6]
Dye-X + OH-Cell Dye-O-Cell
Reactive dye (Permanently fixed dyes)
(X is the reactive component)
44 PTJ April 2011
The two most commonly encountered reactive dyes have
chlorotriazine (CT), vinyl sulfone (VS), or CT-VS heterobifunctional
functionality. Reactive dyes form covalent ether bonds like
above with cellulose. With the chlorotriazine reactive group, the
Cl group is replaced by the Cell-O- group through a nucleophilic
substitution reaction. Both types <strong>of</strong> reactive groups can be used in
the same dye structure to increase fixation. Reactive dye classes
include trichloropyrimidine, mono-chlorotriazine (MCT), carboxypyridino
triazine, dichloroquinoxaline, mon<strong>of</strong>luoro- triazine,
difluoropyrimidine, difluorochloro- pyrimidine, and phosphonic
acid dyes. Reaction between the dye and cellulose can occur
when the dye has been absorbed into the cellulose phase. Thus
the kinetic <strong>of</strong> the dye cellulose reaction are strongly influenced by
the rate <strong>of</strong> absorption <strong>of</strong> dye.
The ratio <strong>of</strong> the rate constant for reaction <strong>of</strong> the dye with the
fibre and with water is a constant for a given dye over a wide
range <strong>of</strong> alkaline pH values. [7] The processing <strong>of</strong> cotton with fibre
reactive dyes requires the following aspects to be considered:
electrolyte, bath ratio, alkali (pH) and temperature. Most (98%)
commercial reactive dyes are fixed under alkaline conditions.In
order to achive maximum wash fastness <strong>of</strong> a reactive dyeing, the
hydrolysed dye which is present in the fibre and held by weaker
affinity forces, than covalency, should be completely removed, as
otherwise it would lower the wash fastness <strong>of</strong> the dyeing because
<strong>of</strong> its lower substantivity to cellulose. That is usually removed by
soaping treatment at the boil. [8]
After soaping, <strong>fixing</strong> process is carried out on dyed material
with <strong>fixing</strong> <strong>agent</strong> to prevent color bleeding during subsequent
washing and improve different color fastness properties. Fixing
<strong>agent</strong> is a cross-linking <strong>agent</strong> which would form a strong bridge
between the cellulose and the dye, thereby anchoring the latter
to the fibre. [9]
2. Materials & methods
2.1. Materials selection:
The investigation has been carried out with currently popular
Single jersey knitted fabric. Basic characteristics <strong>of</strong> single jersey
fabric are mentioned below:
Fabric composition – 100% cotton
Fabric type – Single jersey weft knitted fabric.
Yarn count – 30/s
Fabric G.S.M –158
Fabric wt – 10 gm

2.2 Method <strong>of</strong> Scouring and Bleaching:
The process by which natural colour bodies are completely
removed and permanent whiteness effects are produced on fabric
is called bleaching. Scouring was done in combine with bleaching
process to remove impurities from cotton fabric. Following recipe
has been introduced for those purposes-
Detergent (Sandoclean PCLF) -1 g/l
Peroxide Stabilizer -0.75 g/l
Bleaching Agent (H2O2 ) -4 g/l
Alkali (NaOH) -3g/l
Sequestering Agent (UDX) -0.5 g/l
Temperature - 95˚C
Time – 1hour
Material: Liquor – 1:10
Figure 2: Scouring and bleaching curve.
2.3 Method <strong>of</strong> dyeing:
In this investigation reactive dyes <strong>of</strong> red hue have been taken
for dyeing the bleached fabric with shade 0.5% and 1.5%. Dye-
A, Dye-B and Dye-C have been collected from three reactive
dyestuff manufacturers.
Table 1: Dyeing recipe with Dye-A, Dye-B and Dye-C
Dyeing Parameters 0.5% shade 1.5% shade
Reactive dyes (Dye-A,
Dye-B, Dye-C)
0.5% 1.5%
Common salt (g/l) 20 45
Soda ash (g/l) 5 12
Levelling <strong>agent</strong> (g/l) 0.5 0.5
Temperature (˚C) 60 60
Run time (minutes) 60 60
Material: liquor 1:10 1:10
Figure 3: Dyeing curve.
2.4 Method <strong>of</strong> soaping
After dyeing soaping treatment was carried out on dyed samples
with recipe mentioned below:
Soaping <strong>agent</strong> – 1 g/l
Temperature - 60˚C
Time – 5 minutes
Material: Liquor – 1:10
Figure 4: Soaping curve.
2.5 Method <strong>of</strong> neutralization
After the soaping treatment, neutralization has been performed
on dyed fabric at normal temperature with 0.5 g/l acetic
acid to remove the residual alkalinity if present in fabric.
2.6 Method <strong>of</strong> <strong>fixing</strong>:
Fixing is done by using <strong>fixing</strong> <strong>agent</strong> after soaping process.
Following recipe & procedure was used for the fixation <strong>of</strong> reactive
dyes with fibre.
Fixing <strong>agent</strong> – 1 g/l
Temperature - 45˚C
Time – 10 minute
Material: Liquor – 1:10
Figure 5: Fixing curve.
2.7 Method <strong>of</strong> Testing:
Different testing standard procedures have been followed for
the assessment <strong>of</strong> colour fastness properties and colour difference
values among the dyed samples before and after <strong>fixing</strong> treatment.
2.7.1Color fastness to rubbing (wet & dry):
Colourfastness to both dry and wet rubbing <strong>of</strong> dyed cotton
single jersey fabric was assessed by following standard method
ISO 105 X12.
2.7.2 Colour fastness to washing:
Colourfastness to wash <strong>of</strong> dyed cotton single jersey fabric was
assessed by following standard method ISO105-C2S.
2.7.3 Colour difference (∆E) measurement:
By using the Spectrophotometer, firstly dyed sample without
<strong>fixing</strong> is taken as standard. Then the colour difference (∆E) among
the samples before and after <strong>fixing</strong> was measured. SF-600 model
<strong>of</strong> DATA COLOR (USA) was used for the measurement <strong>of</strong> Colour
difference (∆E) value.
3.0 Results & discussions
3.1 Effects <strong>of</strong> <strong>fixing</strong> <strong>agent</strong> on colour fastness to rubbing <strong>of</strong> different
shades:
Table 2: Effects <strong>of</strong> <strong>fixing</strong> <strong>agent</strong> on colourfastness to
dry rubbing <strong>of</strong> 0.5% shade
(Grey scale rating for colour change)
Sample (After different Process) Dye A Dye B Dye C
Dyed Sample 4-5 4 4-5
After Soaping 4-5 4-5 5
After Soaping and Fixing 5 4-5 5
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Dyeing Printing Finishing

Dyeing Printing Finishing
Figure 6: Colourfastness to dry rubbing <strong>of</strong> various dyes for 0.5 % shade.
The figure is showing that after using <strong>fixing</strong> <strong>agent</strong> the colour
fastness to dry rubbing is increased for all dyes, where exception
has been found if <strong>fixing</strong> is not done after dyeing process. So, from
the above figure it can be said that the colourfastness to dry rubbing
<strong>of</strong> dye (A) and (C) is superior to dye (B) though same <strong>fixing</strong>
<strong>agent</strong> was used during <strong>fixing</strong> process.
Table 3: Effect <strong>of</strong> <strong>fixing</strong> <strong>agent</strong> on colourfastness
to wet rubbing <strong>of</strong> 0.5% shade
(Grey scale rating for colour change)
Sample (After different Process) Dye A Dye B Dye C
Dyed Sample 3-4 3-4 4
After Soaping 4 4 4-5
After Soaping and Fixing 5 4-5 5
Figure 7: Colourfastness to wet rubbing <strong>of</strong> various dyes for 0.5 % shade.
The figure is showing that after using <strong>fixing</strong> <strong>agent</strong> the colour
fastness to wet rubbing is increased for all dyes, where exception
has been found if <strong>fixing</strong> is not done after dyeing process. So, from
the above figure it can also be said that the colourfastness to wet
rubbing <strong>of</strong> dye (A) and (C) is superior to dye (B) though same
<strong>fixing</strong> <strong>agent</strong> was used during <strong>fixing</strong> process.
Table 4: Effects <strong>of</strong> <strong>fixing</strong> <strong>agent</strong> on colour fastness to
dry rubbing <strong>of</strong> 1.5% shade
(Grey scale rating for colour change)
Sample (After different Process) Dye A Dye B Dye C
46 PTJ April 2011
Dyed Sample 3-4 4 4
After Soaping 4 4 4-5
After Soaping and Fixing 4-5 5 5
Figure 8: Colourfastness to dry rubbing <strong>of</strong> various dyes for 1.5 % shade.
The figure is showing that after using <strong>fixing</strong> <strong>agent</strong> the colour
fastness to dry rubbing is increased for all dyes, where exception
has been found if <strong>fixing</strong> is not done after dyeing process. So, from
the above figure it can also be said that the colourfastness to dry
rubbing <strong>of</strong> dye (B) and (C) is superior to dye (A) though same
<strong>fixing</strong> <strong>agent</strong> was used during <strong>fixing</strong> process.
Table 5: Effects <strong>of</strong> <strong>fixing</strong> <strong>agent</strong> on colourfastness to
wet rubbing <strong>of</strong> 1.5% shade
(Grey scale rating for colour change)
Sample (After different processes) Dye A Dye B Dye C
Dyed Sample 3-4 3-4 4
After Soaping 4 4 4
After Soaping and Fixing 4 4-5 4-5
Figure 9: Colourfastness to wet rubbing <strong>of</strong> various dyes for 1.5 % shade.
The figure is showing that after using <strong>fixing</strong> <strong>agent</strong> the colour
fastness to wet rubbing is increased for all dyes, where exception
has been found if <strong>fixing</strong> is not done after dyeing process. So, from
the above figure it can also be said that the colourfastness to wet
rubbing <strong>of</strong> dye (B) and (C) is superior to dye (A) though same
<strong>fixing</strong> <strong>agent</strong> was used during <strong>fixing</strong> process.
3.2 Effects <strong>of</strong> <strong>fixing</strong> <strong>agent</strong> on colour fastness to washing <strong>of</strong>
different shades:
Table 6: Effect <strong>of</strong> <strong>fixing</strong> <strong>agent</strong> on colourfastness to
wash <strong>of</strong> 0.5% shade (Grey scale rating)
Sample (After different Process) Dye A Dye B Dye C
Dyed Sample 3 4 3-4
After Soaping 3-4 3-4 4
After Soaping and Fixing 4-5 4 4-5

Figure 10: Colourfastness to wash <strong>of</strong> various dyes for 0.5 % shade.
The figure is showing that after using <strong>fixing</strong> <strong>agent</strong> the colour
fastness to wash is increased for all dyes, where exception has
been found if <strong>fixing</strong> is not done after dyeing process. So, from the
above figure it can also be said that the colourfastness to wash <strong>of</strong>
dye (A) and (C) is superior to dye (B) though same <strong>fixing</strong> <strong>agent</strong>
was used during <strong>fixing</strong> process.
Table 7: Effect <strong>of</strong> <strong>fixing</strong> <strong>agent</strong> on colourfastness to
wash <strong>of</strong> 1.5% shade
(Grey scale rating for colour change)
Sample (After different Process) Dye A Dye B Dye C
Dyed Sample 3-4 4 4
After Soaping 4 4 4
After Soaping and Fixing 4-5 4-5 4-5
Figure 11: Colourfastness to wash <strong>of</strong> various dyes for 1.5 % shade.
The figure is showing that after using <strong>fixing</strong> <strong>agent</strong> the colour
fastness to wash is increased for all dyes, where exception has
been found if <strong>fixing</strong> is not done after dyeing process. So, from the
above figure it can also be said that the colourfastness to wash <strong>of</strong>f
dye (A), dye (B) and dye (C) is good.
3.3 Effects <strong>of</strong> <strong>fixing</strong> <strong>agent</strong> on Colour difference (∆E) among
different shades:
Table 8: Effect <strong>of</strong> <strong>fixing</strong> <strong>agent</strong> on Colour
difference <strong>of</strong> 0.5% shade
(Spectrophotometer readings)
Colour difference (∆E) between dyed
sample and sample without Fixing
Colour difference (∆E) between dyed
sample and sample with Fixing
Figure 12: Colour difference (∆E) value <strong>of</strong> various samples.
Dye A Dye B Dye C
4.9 4.2 2.64
2.18 3.15 0.64
The figure is showing that after using <strong>fixing</strong> <strong>agent</strong> the colour difference
(∆E) among various samples is decreased significantly for all dyes,
where exception has been found if <strong>fixing</strong> is not done after dyeing
process. So, from the above figure it can be said that the colour difference
is decreased in greater amount after <strong>fixing</strong> in case <strong>of</strong> dye (A) as
compare to dye (B) and dye (C). Again colour difference was minimum
for samples dyed with dye (C) before and after <strong>fixing</strong>.
Table 9: Effect <strong>of</strong> <strong>fixing</strong> <strong>agent</strong> on Colour difference
<strong>of</strong> 1.5% shade (Spectrophotometer readings)
Colour difference (∆E) between dyed
sample and sample without Fixing
Colour difference (∆E) between dyed
sample and sample with Fixing
Figure 13: Colour difference ( E) value <strong>of</strong> various samples.
The figure is showing that after using <strong>fixing</strong> <strong>agent</strong> the colour difference
(∆E) among various samples is decreased significantly for all dyes,
where exception has been found if <strong>fixing</strong> is not done after dyeing
process. So, from the above figure it can be said that the colour difference
is minimum for samples dyed with dye (C) before and after <strong>fixing</strong>.
4.0 Conclusion
After the completion <strong>of</strong> this investigation it has been observed
that after using <strong>fixing</strong> <strong>agent</strong>, the colour fastness <strong>of</strong> reactive dyed
cotton fabric is increased significantly in case <strong>of</strong> dye (C) as compared
to dye (A) and dye (B). Again, colour difference (∆E)
among the various samples at different stages for dye (C) has
been reduced after using <strong>fixing</strong> <strong>agent</strong>. So, <strong>fixing</strong> <strong>agent</strong> showed
greater effects in case <strong>of</strong> reactive dye (C) and thus its effects
depend on different types <strong>of</strong> manufactured reactive dyes.
Colourfastness tests are very much important in case <strong>of</strong> textile
processing for the selection <strong>of</strong> suitable dyes.
By these tests it was possible to know and asses how long the
colour would be retained in textiles material, its longevity, substantivity,
resistance etc. All the tests were executed according to world
recognized ISO standards. Colour fastness to washing, rubbing is
very much important criterion to buy a dyed cloth. So, it is necessary
to study the importance <strong>of</strong> <strong>fixing</strong> <strong>agent</strong> on cotton fabric dyed with
reactive dyes supplied from various dye manufacturers.
References
Dye A Dye B Dye C
1.9 1.7 1.35
1.1 0.9 0.75
[1] John Shore: Cellulosics dyeing, 1995: pp. 01
[2] Encyclopedia Britannica Online, Retrieved January 11, 2008.
[3] http://en.wikipedia.org/wiki/ Cellulose (Downloaded: 21-07-2009, 02:12 pm)
[4] Dr. Charles Tomasino: Chemistry and Technology <strong>of</strong> Fabric Preparation and
Finishing, USA, 1992, pp. 31
[5] Dr. Charles Tomasino: Chemistry and Technology <strong>of</strong> Fabric Preparation and
Finishing, USA, 1992, pp. 60
[6] S.B. Srivastva: Recent Process <strong>of</strong> Textile Bleaching Dyeing and Finishing, Small
Business Publications, Delhi, 2003, pp. 52
[7] John Shore: Cellulosics dyeing, Society <strong>of</strong> Dyers and Colourists, England, 1995,
pp. 211
[8] Dr. V.A. Shenai: Technology <strong>of</strong> Textile processing Vol-II, Sevak Publications,
Bombay, 1993, pp. 513
[9] E.R. Trotman: Dyeing and Chemical Technology <strong>of</strong> Textile fibre, Charles Giffin
and Company, 1975, pp. 563.
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Dyeing Printing Finishing