Dyeing of polyester with disperse dyes: Part 2. Synthesis and dyeing characteristics of some azo disperse dyes for polyester fabrics

Article abstract of DOI:10.3390/molecules21070855

The goal of this study was to utilize carrier for accelerating the rate of dyeing not only to enhance dyeing of polyester fabrics dyed with disperse dyes 3a,b, but also to save energy. Both the color strength expressed as dye uptake and the fastness prope

Full text of DOI:10.3390/molecules21070855

molecules
Article
Dyeing of Polyester with Disperse Dyes: Part 2.
Synthesis and Dyeing Characteristics of Some Azo
Disperse Dyes for Polyester Fabrics
Alya M. Al-Etaibi 1,*, Huda S. Alnassar 2 and Morsy Ahmed El-Apasery 3
1
Natural Science Department, College of Health Science, Public Authority for Applied Education and
Training, Fayha 72853, Kuwait
Department of Laboratories Technology, College of Technological Studies,
2
Public Authority for Applied Education and Training, Fayha 70654, Kuwait; hsalnassar@yahoo.com
Dyeing, Printing and Textile Auxiliaries Department, Textile Research Division, National Research Centre,
3
33 El Buhouth St., Dokki, Cairo 12311, Egypt; elapaserym@yahoo.com
*
Correspondence: alya_aletaibi@yahoo.com; Tel.: +965-99-807-246
Academic Editor: Wim Dehaen
Received: 22 May 2016; Accepted: 24 June 2016; Published: 29 June 2016
Abstract: The goal of this study was to utilize carrier for accelerating the rate of dyeing not only to
enhance dyeing of polyester fabrics dyed with disperse dyes 3a,b, but also to save energy. Both the
color strength expressed as dye uptake and the fastness properties of the dyed fabrics were evaluated.
Keywords: polyester fabric; fastness properties; dyeing characteristics; carriers
1. Introduction
Disperse dyes cause environmental concern due to their widespread utility which has been
increased in the textile industry since the discovery of synthetic fibers such as polyester. Disperse dyes
have particularly low water solubility and to be used from this medium, they must be milled to a
very low particle size and dispersed in water using a surfactant (dispersing agent), or else a carrier
must be added during dyeing or printing [1–4]. The real mechanism by which carriers accelerate
textile coloration is well known. Polyester fabrics absorb carriers and swell. This swelling can slow
down liquor flow in packaging causing lowering of the polymer glass transition temperature (Tg),
thus promoting polymer chain movements and creating free volume. This accelerates the distribution
of the dye into the fabrics. Alternatively, the carrier may form a film around the surface of the fabrics
wherein the dye is soluble, thus increasing the rate of transfer into the fabric [5–7].
This paper aims to show the capability of dye adsorption into the fabrics under normal
conditions of pressure and temperature in the presence of carrier in an attempt to get high dye
uptake; consequently, the amount of dyed, wasted water is reduced and this eliminates hazardous to
the environment.
2. Results and Discussion
2.1. Chemistry
The synthesis of some dyes based on dimethylamino-p-arylpropenones derivatives has reported
by us [8]. Herein, in an attempt to estimate their dyeing characteristics, enaminones 1a,b react with
phenyl diazonium salts 2 in acidic medium to afford disperse dyes 3a,b (Scheme 1).
Molecules 2016, 21, 855; doi:10.3390/molecules21070855
www.mdpi.com/journal/molecules

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O
O
H
O
N
-
X
NH
CH3
+
N
PhN N Cl
2
CH3
X
1a, X = CH3
b, X = NO2
3a, X = CH3
b, X = NO2
Scheme 1. Synthesis of disperse dyes 3a,b.
Disperse dyes 3a,b were applied to polyester fabrics at 2% shade, without or with using
commercial HC carrier at different dyeing temperatures of 70, 90 and 100 ˝C. Greenish-yellow and
yellowish-orange color shades were obtained. The dyeing properties on the polyester fabrics were
estimated in terms of their fastness properties (washing, rubbing, light and perspiration). The surface
color yield K/S was used to give details on the amount of dye absorbed on the surface of the polyester
fabrics. The K/S values outlined in (Tables 1 and 2) show that dyes 3a,b showed high affinity for the
polyester fabrics.
Table 1. Optical measurements of disperse dye 3a on the polyester fabrics.
Dyeing Temp.
% Carrier
K/S
L*
a*
b*
C*
h*
∆E
0
1
2
3
4
5
0.93
1.17
1.19
2.60
1.68
1.92
87.83
87.91
87.25
86.26
87.47
87.51
´3.14
´4.66
´5.73
´8.18
´7.48
´8.59
4.06
8.02
11.47
17.57
16.44
20.05
5.13
9.28
12.82
19.36
18.06
21.81
127.57
120.16
116.56
114.85
114.45
113.20
87.98
88.40
88.19
88.40
89.32
90.19
70 ˝C
0
1
2
3
4
5
6.53
7.65
8.32
8.90
7.30
6.37
84.86
85.08
84.98
84.79
85.31
85.33
´12.67
´13.08
´13.72
´13.42
´13.48
´12.95
´12.70
´13.26
´13.65
´14.11
´14.26
´14.05
39.74
41.58
43.31
54.47
39.82
83.59
41.71
43.59
45.43
47.04
42.04
40.70
107.68
107.46
107.58
106.44
108.70
108.55
94.56
95.60
96.36
97.14
95.10
94.54
90 ˝C
0
1
2
3
4
5
6.34
6.80
7.72
9.70
12.21
10.12
84.82
84.83
84.95
84.82
84.81
84.75
83.64
41.02
43.28
48.32
52.16
48.40
40.68
43.11
45.38
50.34
54.08
50.39
108.19
106.91
107.51
106.27
105.29
106.19
94.07
95.16
96.31
98.63
99.58
98.44
100 ˝C
Table 2. Optical measurements of disperse dye 3b on the polyester fabrics.
Dyeing Temp.
% Carrier
K/S
L*
a*
b*
C*
h*
∆E
0
1
2
3
4
5
1.69
1.85
1.87
2.13
2.04
2.10
83.92
83.08
84.37
82.61
83.25
82.83
´1.84
´1.40
´1.52
´1.08
´2.83
´2.86
16.74
22.01
12.80
26.28
24.52
27.35
16.85
22.06
12.89
26.30
24.68
27.50
96.28
93.64
96.76
92.35
96.59
95.98
23.29
28.54
19.33
32.78
31.13
33.97
70 ˝C
0
1
2
3
4
5
3.34
3.47
3.90
5.15
4.73
5.12
80.37
80.77
81.26
80.43
81.33
80.06
´0.67
´1.64
´3.19
´1.13
´2.42
´2.07
39.36
40.94
42.35
43.50
41.72
43.69
39.38
40.97
42.47
43.51
41.79
43.47
90.98
92.29
94.30
91.84
93.32
92.71
46.00
47.55
48.99
50.10
48.29
50.40
90 ˝C

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Table 2. Cont.
Dyeing Temp.
% Carrier
K/S
L*
a*
b*
C*
h*
∆E
0
1
2
3
4
5
3.93
4.49
5.85
5.92
8.97
7.71
79.81
80.23
78.46
79.28
78.08
77.87
´0.19
´1.27
´1.12
0.11
41.51
44.49
49.55
46.04
51.20
50.33
41.52
44.50
49.57
46.06
51.21
50.38
90.26
91.64
88.71
89.86
90.23
87.34
48.20
51.11
56.34
52.75
58.04
57.21
100 ˝C
´0.21
2.34
2.2. Effect of Concentration of Carrier
The rate of dye diffusion can be strengthened by increasing the permeability of the fabrics, by
increasing the ability of the fabrics to swell. This can be obtained by additional compounds (with
smaller molecules than the dye molecules and with definite affinity towards the fabric) in the dye
bath. These compounds are named as carriers, as a result of their small molecule size, and they rapidly
distribute into the fabrics. The use of carriers is a well-known method for increasing the speed of the
distribution of dyes in polyester fabrics. Carriers incite the loosening of the fabric microstructure [9].
Commercial HC was selected as an accelerator or as a carrier to be added to the dye bath to assist the
dyeing process, especially if the dyeing process was carried out under the boiling point.
Figures˝1 and 2 show that in the case of dyeing polyester fabrics with disperse dyes 3a
,b
at 70 and 90 C, with the increase of the concentrations of the carrier from zero (without using carrier)
to 5% of the weight of the fabric, there is a slight increase of color strength K/S values until a 3%
concentration of the carr˝ier. In the case of dyeing polyester fabrics with dispersed dyes 3a
,b at the
boiling temperature (100 C), the highest color strength K/S value was obtained at a 4% concentration
of the carrier. Moreover, the
the carrier.
∆
E of both dyes 3a,b increases with the increase of the concentration of
13
70 ºC
12
90 ºC
100 ºC
11
10
9
8
7
6
5
4
3
2
1
0
0
1
2
3
4
5
Concentration of Carrier %
Figure 1. Effect of the concentration of carrier on the dyeing for disperse dye 3a at different
dyeing temperatures.

Molecules 2016, 21, 855
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10
9
8
7
6
5
4
3
2
1
0
70 ºC
90 ºC
100 ºC
0
1
2
3
4
5
Concentration of Carrier %
Figure 2. Effect of the concentration of carrier on the dyeing for disperse dye 3b at different
dyeing temperatures.
It can be concluded from the data in Table 1 that the color strength K/S value of the pretreated
fabric with disperse dye 3a increases by increasing the carrier concentration to 3% and 4% at different
dyeing temperatures of 70, 90 and 100 ˝C. The maximum color strength K/S values (2.60, 8.90 and
12.21) were obtained, since the color strength K/S values are found to increase by about 179%, 36%
and 92%, respectively, compared to those of the sample dyed without adding carrier. Also, it can be
concluded from the data in Table 2 that color strength K/S values of the pretreated fabric with disperse
dye 3b increase by increasing the carrier concentration to 3% and 4% at different dyeing temperatures
of 70, 90 and 100 ˝C. The maximum color strength K/S values (2.13, 5.15 and 8.97) were obtained,
since the color strength K/S values are found to increase by about 26%, 54% and 128%, respectively,
compared to those of the sample dyed without adding carrier. Carriers play an important role in
dyeing polyester fabrics, especially when the dyeing process is carried out under atmospheric pressure.
Commercial HC acts as a carrier or plasticizing agent for polyester fabrics, resulting in increasing the
number and size of voids within which the molecules of disperse dye can distribute faster inside the
molecular structure of the polyester fabrics.
2.3. Effect of Dyeing Temperature
To study the significance of dyeing temperature in the dyeing process, the pretreated samples
were dyed at different degrees of temperature (70, 90 and 100 ˝C); after that, the color strength K/S
values of the dyed samples were considered. Figures 1 and 2 show that as the temperature of the
dyeing of polyester fabrics with disperse dyes 3a,b
increases from 70 to 100 ˝C, the color strength
K/S values increase for both dyes without or with carrier, and this may be attributed to the high
distribution rate and the increase of the kinetic energy of the dye molecules [10].
Moreover, the
∆
E of both dyes 3a
,
b
increases by increasing the dyeing temperatures. It is observed
increase
from Tables 1 and 2 that the K/S values of the pretreated samples dyed with disperse dyes 3a,b
by raising the dyeing temperature, especially when raising the temperature from 70 to 90 ˝C, since
there was a notable increase in the color strength K/S.
The increasing percentages in K/S are 242% and 141%, respectively. In the same way, the K/S
values of the dyed samples with disperse dyes 3a,b increase, by raising the dyeing temperature from
˝
90 to 100 C, to 37% and 74%, respectively.
This could be due to the possibility of the existence of dye molecules in an aggregated form at
lower temperatures, so the solubility will increase at higher temperatures of dyeing [11]. In addition,
the carrier is able to penetrate from boiling solutions inside the fabrics.

Molecules 2016, 21, 855
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Alternatively, the temperature shows a very valuable function in establishing the state of the
molecular polymer chains. By raising the temperature, the movement speed of the segment polymer
chains is increased, resulting in a decrease in the glass transition temperature (Tg) in addition to the
dyeing transition temperature (Td) decrease. Therefore, the number and volume of voids will be
greater and the diffusion of disperse dye molecules will be easier and faster; thus, a higher amount of
dye inside the fabric and, consequently, a higher color strength are obtained. It is distinguished that the
rate of dye uptake, in addition to the total dye uptake, increases with an increase in temperature [12
since the dyeing route is endothermic [13 14]. The fastness ratings are outlined in Table 3, showing that
the disperse dyes displayed excellent fastness levels to washing, rubbing and perspiration. The light
fastness of the dyes 3a displayed fair fastness on polyester fabrics. It is of value to mention here that
]
,
,b
carrier dyeing improves the washing fastness. Attempts are being undertaken to improve the light
fastness of the dyed samples by using zinc oxide nanoparticles, and added value will also be obtained,
e.g., self-cleaning, absorbing UV radiation, and antibacterial textiles.
Table 3. Fastness properties of azo disperse dyes on polyester fabrics.
Perspiration Fastness
Alkaline Acidic
Washing
Fastness
Rubbing
Fastness
Dye
No
Light
Fastness
Alt
SC
SW
Dry
Wet
Alt
SC
SW
Alt
SC
SW
3a
3b
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
3–4
3–4
Alt = alteration; SC = staining on cotton; SW = staining on wool.
3. Materials and Methods
3.1. General Procedure for the Synthesis of Disperse Dyes (3a,b)
A cold solution of the diazonium salt (10 mmol), prepared by adding a cold solution of sodium
nitrite (0.7 g) in water (10 mL) to a solution of aniline (10 mmol) in conc. hydrochloric acid (4 mL), was
added to a cold solution of dimethylamino-p-arylpropenones 1a or 1b (10 mmol) in ethanol (15 mL)
containing sodium hydroxide (1.2 g). The resulting mixture was stirred at room temperature for 30 min.
The precipitate that formed was collected by using filtration and crystallized from ethanol. Dyes 3a,b
were confirmed by the reported data [8].
3-Oxo-2-(phenylhydrazono)-3-p-tolyl-propionaldehyde (3a). This compound was obtained as greenish-
yellow powder (86%); IR (KBr): = 3130 (NH), 1662, 1635 cm´1 (2CO); 1H-NMR (DMSO-d6):
= 2.41
δ
(s, H, CH3), 7.21–7.54 (m, 9H, arom-H), 9.98 (s, 1H, CHO, D2O exchangeable), 14.21 (s, 1H, NH, D2O
exchangeable). MS, m/z (%), 266 (M+, 100), Anal. Calcd. for C16H14N2O2; C, 72.16; H, 5.30; N, 10.52.
Found: C 71.99; H 5.33; N 10.23.
3-(4-Nitrophenyl)-3-oxo-2-(phen˝ylhydrazono)-propionaldehyde (3b). This compound was obtained as
orange powder (84%); mp. 190 C IR (KBr): = 3127 (NH), 1660, 1633 cm´1 (2CO); 1H-NMR (DMSO-d6):
7.11–7.83 (m, 9H, arom-H), 9.92 (s, 1H, CHO, D2O exchangeable), 14.18 (s, 1H, NH, D2O exchangeable).
MS, m/z (%), 297 (M+, 100), Anal. Calcd. for C15H11N3O4; C, 60.61; H, 3.73; N, 14.14. Found: C, 60.61;
H, 3.69; N, 14.48.
3.2. Fabrics
Scoured and bleached 100% polyester fabric was supplied by El-Mahalla El-Kobra Company,
El-Mahalla, Egypt. The fabrics were scoured in aqueous solution having a liquor ratio of 1:50 and
containing 2 g/L of nonionic detergent solution (Hostapal; Clariant, Swiss, Switzerland) and 2 g/L of

Molecules 2016, 21, 855
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˝
Na2CO3 at 50 C for 30 min to remove waxes and impurities, then rinsed thoroughly in cold tap water,
and dried at room temperature.
3.3. Dyeing Process
Dyes 3a,b were used as pure powder in the same form as prepared without milling. Fabric
samples (2 g) were introduced into a flask containing a dyebath of 2% (o.w.f) dye shade and Matexil
DA-N (supplied by ICI Company, London, UK) as dispersing agent, commercial HC carrier (Liquid)
supplied by Egyptian Turkish Co. (Cairo, Egypt) for auxiliaries with different ratio 0–5% (o.w.f) at
˝
different dyeing temperatures 70, 90 and 100 C with a 1:50 liquor ratio. During dyebath preparation,
the dye was mixed with 10 drops of DMF and then mixed with dispersing agent, and water was
added to prepare a homogeneous dispersion of the dye. The pH was adjusted to 4.5 by using acetic
acid. At the end of the dyeing process after 1 h, the dyed samples were removed, rinsed in warm
water, and subjected to reduction clearing in a solution comprising 2 g/L of sodium hydrosulphite
and 2 g/L of sodium hydroxide (caustic soda) for 10 min at 60 ˝C, with a liquor ratio of 1:40, and the
reduction-cleared sample was rinsed thoroughly in water. The dyed samples were removed, rinsed in
tap water, and allowed to dry in the open air.
3.4. Color Measurements
The colorimetric parameters of the dyed polyester fabrics were determined on a reflectance
spectrophotometer. The color yields of the dyed samples were determined by using the light
reflectance technique performed on an UltraScan PRO D65 UV/VIS Spectrophotometer (HunterLab,
Reston, VA, USA). The color strengths, expressed as K/S values, were determined by applying the
Kubelka-Munk equation:
2
2
K{S “ rp1 ´ Rq {2Rs ´ rp1 ´ Roq {2Ros
(1)
where R is the reflectance of colored samples and K and S are the absorption and scattering coefficients,
respectively. Ro = decimal fraction of the reflectance of the undyed fabric.
CIE Lab Difference
1
2
2
2
2
∆E “ p∆L ` ∆a ` ∆b q
(2)
∆
E: the total color difference between the sample and the standard: L represents the white-black axis,
a represents the red-green axis and finally b represents the yellow-blue axis.
3.5. Fastness Properties
Fastness properties of the dyed samples were tested to rubbing, perspiration, washing and light
fastness according to AATCC standard tests [15].
4. Conclusions
The color strength K/S and ∆E exhibited a significant increasing from using a dyeing method
with a commercial HC carrier. The obtained results gave excellent fastness properties to washing,
rubbing, perspiration and fair light fastness levels as well. Also, the dyeing process with a carrier for
polyester fabrics has great advantages such as saving energy when dyeing at low temperatures with a
better dye uptake.
Author Contributions: A.M.A. and M.A.E. conceived and designed the experiments; M.A.E. and H.S.A.
performed the experiments. All authors analyzed the data; A.M.A. and M.A.E. wrote the paper.
Conflicts of Interest: The authors declare no conflict of interest.
References
1.
Reigel, E.R.; Kent, J.A. Riegel’s Handbook of Industrial Chemsitry, 10th ed.; Springer Pub: New York, NY, USA,
2003; pp. 896–904.

Molecules 2016, 21, 855
7 of 7
2.
3.
4.
5.
Broadbent, A.D. Basic Principles of Textile Coloration, Society of Dyers and Colorists; Thanet Press Ltd: Kent,
West Yorkshire, England, 2001; pp. 322–331.
Lai, C.C.; Chen, K.M. Dyeing properties of modified gemini surfactants on a disperse dye-polyester system.
Text. Res. J. 2008, 78, 382–389. [CrossRef]
Ren, Z.; Qin, C.; Tanga, R.C.; Chen, G. Study on the dyeing properties of hemicyanine dyes. II. Cationic
dyeable polyester. J. Soc. Dyers Colour. 2012, 128, 147–152. [CrossRef]
Al-Etaibi, A.M.; Al-Awadi, N.A.; El-Apasery, M.A.; Ibrahim, M.R. Synthesis of some novel
pyrazolo[1,5-a]pyrimidine derivatives and their application as disperse dyes. Molecules 2011, 16, 5182–5193.
[CrossRef] [PubMed]
6.
7.
8.
9.
El-Apasery, M.A. Solvent-free one-pot synthesis of some azodisperse dyes under microwave irradiation:
Dyeing of polyester fabrics. J. Appl. Polym. Sci. 2008, 109, 695–699. [CrossRef]
El-Apasery, M.A. Synthesis of some azo dispersedyes by the use of focused microwave heating. Pol. J.
Appl. Chem. 2006, 50, 75–81.
Al-Etaibi, A.; El-Apasery, M.A.; Kamel, M.M. Dyeing of polyester with disperse dyes: Part 1. Antimicrobial
activity and dyeing performance of some disperse dyes. Int. J. Curr. Microbiol. Appl. Sci. 2015, 4, 923–928.
Sadov, F.; Korchagin, M.; Matetsky, A. Chemical Technology of Fibrous Materials, 1st ed.; Mir Publishers:
Moscow, Russia, 1973; pp. 332–336.
10. Mashaly, H.M.; Abdelghaffar, R.A.; Kamel, M.M.; and Youssef, B.M. Dyeing of Polyester Fabric using Nano
Disperse Dyes and Improving Their Light Fastness using ZnO Nano Powder. Ind. J. Sci. Technol. 2014, 7,
960–967.
11. Ding, M.; Ma, S.; Liu, D. Simultaneous Determination of Hydroxyanthraquinones in Rhubard and
Experimental Animal Bodies by High-Performance Liquid Chromatography. Anal. Sci. 2003, 19, 1163–1165.
[CrossRef] [PubMed]
12. Gupta, D.; Kumari, S.; Gulrajani, M. Dyeing studies with hydroxyanthraquinones extracted from Indian
madder. Part 2: Dyeing of nylon and polyester with nordamncanthal. Color. Technol. 2001, 117, 333–336.
[CrossRef]
13. Al-Etaibi, A.M.; El-Apasery, M.A.; Huda, H.M.; Al-Awadi, N.A. One-pot synthesis of disperse dyes under
microwave irradiation: Dyebath reuse in dyeing of polyester fabrics. Molecules 2012, 17, 4266–4280.
[CrossRef] [PubMed]
14. Shahin, M.F.; Ahmed, R.M.; Marie, M.M. Optimizing the Dyeing Process of Alkali-Treated Polyester Fabric
with Dolu Natural Dye. Int. J. Eng. Res. Appl. 2014, 4, 35–40.
15. El-Adasy, A.A.A.M.; Kamel, M.K.; Saleh, M.O.; Hussein, A.M.; El-Apasery, M.A. Disperse Dyes Based on
Pyrazolopyrimidinones I: Their Dyeing Applications and Antimicrobial Activities. Int. J. ChemTech Res. 2016
,
9, 31–38.
Sample Availability: Samples of the compounds 3a,b are available from the authors.
©
2016 by the authors; licensee MDPI, Basel, Switzerland. This article is an open access
article distributed under the terms and conditions of the Creative Commons Attribution
(CC-BY) license (http://creativecommons.org/licenses/by/4.0/).