Synthesis, characterization and properties of a novel environmentally friendly mono azo disperse dye and its application on polyethylene terephthalate (PET)

Article abstract of DOI:10.1002/jccs.201200441

The aim of this research is to achieve the synthesis of a novel mono azo disperse dye containing both a β- naphthyl acetate group and carboxylic acid ester group and application on PET fabric. In this study the dyeing properties have also been investigate

Full text of DOI:10.1002/jccs.201200441

JOURNAL OF THE CHINESE
CHEMICAL SOCIETY
Article
Synthesis, Characterization and Properties of a Novel Environmentally Friendly Mono
Azo Disperse Dye and Its Application on Polyethylene Terephthalate (PET)
Mohammad Dodangeh,a Mehrdad Mohammadian,b,* Norman. S. Allenc and Elmira Pajootana
aYoung Researchers Club, Islamic Azad University, Kashan Branch, Kashan, Iran
bDepartment of Textile Engineering, Islamic Azad University, Kashan Branch, Kashan, Iran
cDepartment of Chemistry and Materials, Facuality of Science and Engineering, The Manchester Metropolitan
University, Manchester, UK
(Received: Aug. 11, 2012; Accepted: Nov. 16, 2012; Published Online: Jan. 3, 2013; DOI: 10.1002/jccs.201200441)
The aim of this research is to achieve the synthesis of a novel mono azo disperse dye containing both a b-
naphthyl acetate group and carboxylic acid ester group and application on PET fabric. In this study the
dyeing properties have also been investigated. The synthesized dye was characterized using UV-Vis,
FTIR, 1H NMR and 13C NMR spectroscopic techniques. To investigate alkali-clearability, both alkali-hy-
drolysis behavior and the effect of its fastness properties with regard to PET fabric were examined. This
dye showed a reasonable level of hydrolysis under relatively mild alkaline conditions. The application of
the dye to PET fabric showed good leveling and building up properties. Estimating fastness properties of
the dyed fabric showed excellent wash, rubbing fastness, good light and sublimation fastness. The results
furthermore displayed that the synthesized dye offers the option of alkali-clearing process over that of a
conventional reduction-clearing process. Therefore, the value of Chemical Oxygen Demand (COD), Bio-
logical Oxygen Demand (BOD) and water pollution as well as the expenditure of production were de-
creased.
Keywords: Alkali-clearable azo disperse dye; Carboxylic acid ester; Polyethylene terephthalate;
Fastness properties; Biuld-up properties; Chromatography.
INTRODUCTION
PET (polyethylene terephthalate) is one of the most
need for a dispersing agent not only in the dyeing process
but also in the dye manufacturing process. Furthermore, al-
kali-clearable disperse dyes have been studied to reduce
the impact of dyeing process on the environment through
the reduction of effluent discharge as well as on the amount
of energy and materials used. The alkali-clearable disperse
dyes were enabled on alkaline treatment to be substituted
for the more costly and environmentally damaging reduc-
tion clearing process since the dyes can be easily hydro-
lyzed and washed off under relatively mild alkaline condi-
tions. Koh et al.3-5,8 have studied a series of alkali-clearable
disperse dyes containing a fluorosulphonyl group and
observed that most of the synthesized dyes had a reason-
able hydrolysis level under relatively mild alkaline condi-
tions.
hydrophobic fibres commonly used in textiles usually dyed
with disperse dyes. The majority of disperse dyes are made
via an azo chromophore.1 The disperse dyes are prepared
by relatively simple manufacturing processes, offering
very wide range of colour gamuts of high colour strength.2
In the manufacturing of new disperse dyes, the effect of
dyeing effluent on the environment should be taken into ac-
count to achieve minimum pollution levels.3-5 This objec-
tive can thus be gained using temporarily solubilised dis-
perse dye in alkalin conditions. In this research the tempo-
rarily solubilised disperse dyes containing a b-naphthyl ac-
etate group have been investigated in the dyeing of PET
fabric. The synthesized dye has sufficient water solubility
at the early stages of the dyeing process without using any
dispersing agent.6-7 During the dyeing process, a number of
soluble dye molecules are gradually decreased with de-
creasing pH value of dyeing solution and then water-insol-
uble form is slowly adsorbed onto the PET fabric.3 There-
fore, the temporarily solubilised dyes can eliminate the
This research is aimed to investigate the synthesis of a
novel disperse dye possessing a carboxylic group followed
by an investigation of the effects of its dyeing properties re-
garding PET fabric due to suitability of the mentioned
group to hydrolysis in alkaline condition. Therefore, a tem-
porarily solubilized alkali-clearable mono azo disperse dye
* Corresponding author. Tel: +98-361-5550055 ext 729; Fax: +98-361-5550056; E-mail: M.mohammadian@iaukashan.ac.ir
J. Chin. Chem. Soc. 2013, 60, 351-354
© 2013 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Article
Dodangeh et al.
was synthesized and its conversion and hydrolysis behav-
iour investigated. The dye has been obtained utilizing p-
amino benzoic acid as the diazo component and b-naphthyl
acetat as the coupling component. For this purpose, p-ami-
no benzoic acid was diazotized and coupled with b-naph-
thyl acetate at alkaline condition to obtain the synthesized
mono azo disperse dye. After obtaining the synthesized
dye, it was applied to PET fabric using the High Tempera-
ture method (HT) and its dyeing properties and COD of
wastewaters were then investigated.
tion. Stirring was continued for 4 h at that temperature and the re-
sulting dye was filtered, washed with hot water and dried. The
crude product was purified using preparation Thin Layer Chro-
matography (TLC) method on silica gel (solvent: chloroform).
UV/Vis (acetone) lmax; 475 nm, emax; 40572 l mol-1cm-1. FTIR
(KBr): 3400-3550 cm-1 (OH, Str: carboxylic acid), 1500.8,
1602.81 cm-1 (C=C, Str: aromatic), 1687.65, 1617.47 cm-1 (C=O,
1
Str: carbonyl), 1425.53 cm1 (N=N). H NMR (d6-DMSO): d
2.49-2.93 (3H, s, -OCOCH3), 6.792 (H, d, J 8.4 Hz, 9CH), 7.465
(H, dd, J1 0.5 J2 8.4 Hz, 8CH), 7.597 (H, ddd, J1 1.5 J2 7.2 J3 8.5
Hz, 5CH), 7.735 (2H, s, 2¢,6¢CH), 7.864 (H, ddd, J1 8.2 J2 7.2 J3
1.3 Hz, 4CH), 7.926 (H, ddd, J1 0.3 J2 1.3 J3 8.5 Hz, 6CH), 7.944
(H, dddd, J1 8.2 J2 1.5 J3 0.3 J4 0.5 Hz, 3CH), 8.04-8.458 (2H, s,
5¢,3¢CH), 11.05 ppm (H, -COOH). 13C NMR (d6-DMSO): d
117.73 (1 C-8), 120.3 (1 C-3), 122.13 (1 C-2), 124.4 (1
-OCOCH3), 125.87 (1 C-4), 127.16 (1 C-5), 127.6 (1 C-4¢),
128.47 (1 C-6), 129.15-129.59 (2 C-2¢,6¢), 129.91 (2 C-3¢,5¢),
130.51 (1 C-10), 131.49 (1 C-7), 133.13 (1 C-1), 142.54 (1 C-1¢),
146.87 (1 -OCOCH3), 167.46 (1 C-9), 176.15 (-COOH). The
chemical structure of the synthesized dye is shown in Fig. 1. The
dye was applied to PET fibres and the effect of their technical
properties in solution and on the fibre were investigated.
Preparation of dispersion
EXPERIMENTAL
Materials and apparatus
p-Amino benzoic acid, b-naphthyl and other materials were
purchased from Aldrich Company and used without further puri-
fication. Melting point was determined using a Differential Scan-
ning Colourimeter 2010 TA instrument. 1H and 13C NMR spectra
were obtained on a Bruker AQS AVANCE 400 MHz spectrome-
ter. UV-Vis absorpation spectra were measured on a Cecil 9200
double beam spectrophotometer, while FTIR spectra were re-
corded on a Nicolet 470/670/870 instrument. The colorimetric
data of the dyeing was obtained using a Gretag Macbeth 7000 A
spectrophotometer (D65 illumination, 10º observer). The COD of
wastewaters were measured using the colorimetric method at 600
nm with UNICO 2100 spectrophotometer (5220.D according to
Standard methods).
The dye (0.5 g), dispersing agent (1 g) (lyoprint EV, Ciba
Geigy) and water (2 cm3) were added to a Mortar and milled for
60 min; the ensuing mixture was diluted with 20 cm3 water, trans-
ferred to a ball mill and milled for 24 h. The volume of the disper-
sion was adjusted to 100 cm3 and filtered through a 5 mm Micro-
Prazisions Sieb Fritsch.
Syntheses of intermediate
To prepare b-naphthyl acetate, b-naphthol (15 g) was dis-
solved in aqueous solution (10%) of sodium hydroxide (75 cm3).
The mixture was colded to 5 ºC using ice (187.5 g). Then anhy-
dride acetic acid (15.15 cm3) was slowly added to the solution.
The solution was stirred for 15-20 minutes and the resulting prod-
uct was filtered. The crude product was purified by column chro-
matography (Silica gel, eluent: acetone/toluene = 2:1).
Synthesis of dye
Dyeing
PET fabric (1 g) was pretreated with 5 g l-1 nonionic deter-
p-Amino-benzoic acid (2.6 g) was slowly added to mixture
of hydrochloric acid (2 cm3) and water (6 cm3). The temperature
of the reaction was increased to 75 °C and the solution was cooled
down to 5 °C. Then hydrochloric acid (3 cm3) and ice (10 g) were
added to the solution. Sodium nitrite (1.44 g) was dissolved in 2.8
cm3 water and this solution was gradually added over 25 min to
the reaction. On the other hand, b-naphthyl acetate (3.39 g) was
dissolved in sodium hydroxide (10%). The resulting clear
diazonium salt solution was used immediately in the designated
coupling component and stirred for 2 h at <10 °C. The pH value
was adjusted between 4 and 5 adding aqueous sodium acetate so-
lution and was maintained at this limit until the end of the reac-
Fig. 1. Chemical structure of the synthesized dye.
352
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JOURNAL OF THE CHINESE
CHEMICAL SOCIETY
Novel Environmentally Friendly Mono Azo Disperse Dye
gent (Lotensol, Hansa) at 80 °C for 20 min using a liquor ratio of
50:1 after which, the substrate was rinsed and dried. Dyeing was
carried out in a Rotadyer (Nasaj Sanat Yazd) using a liquor ratio
of 50:1, pH = 4-5 (using acetic acid) at 0.1, 0.3, 0.5, 0.7, 1, 1.5, 2
and 4% on mass of fabric (o.m.f) (See the dyeing curve in Fig. 2).
At the end of the dyeing operation, excess dye was removed by
subjecting the dyeing to both conventional reduction clearing and
alkali clearing. Reduction clearing was performed at a liquor ratio
of 50:1 using 2 g l-1 sodium hydrosulphite, 1 g l-1 sodium hydrox-
ide and 1 g l-1 nonionic detergent for 20 min at 50 °C. Alkali clear-
ing was carried out using a 50:1 liquor ratio, 2.5 g l-1 sodium hy-
droxide and 1 g l-1 detergent for 30 min at 80 °C. The reduction
cleared and alkali cleared samples were rinsed and dried.
PET fabrics depending on the amounts of dye applied (%
o.m.f). This value is a visually-weighted function of K/S,
which indicates the strength of the dyeing. The synthesized
dye showed reasonable build-up properties on PET and the
fabric was saturated at application levels of 1.5% o.m.f.
Colour fastness properties
The fastness properties of dyed fabrics were investi-
gated and the results were satisfactory. Wash fastness of the
dyed fabrics in two cases after reduction clearing and al-
kali-clearing were excellent but in the case of noncleared
dyed fabrics they showed low wash and rubbing fastness.
Sublimation and light fastness of the dyed fabrics were ex-
cellent and good respectively. On overage alkali-clearig in-
creased the fastness levels but to a smaller extent compared
to the reduction clearing. The fastness properties of the
dyed fabrics are listed in Table 1.
RESULTS AND DISCUSSION
Spectral properties
The correlation between colour and constitution is a
highly interesting aspect of dye development and commer-
cialization; in this context, the absorption wavelength max-
ima (lmax), molar extinction coefficient (emax) and half-
bandwidth (Dl1/2) are important parameters for dyes. A
higher extinction coefficient and a broader half-bandwidth
relate to a stronger chromophore, which makes the product
more cost effective.9 The UV-Visible absorption was deter-
mined in acetone. The lmax of the synthesized dye ranged
from 475 to 490 nm and has an orange shade. The influence
of polar and unpolar solvents such as acetone, chloroform
and DMF on the lmax of the synthesized dye showed that,
changing polarized state of solvent to unpolarized state
caused the lmax absorption to undergo a bathochromic shift.
This is shown in Fig. 3.
Wastewaters Chemical Oxygen Demand (COD)
To investigate the environmental effect of reduction
clearing and the proposed alkali clearing, COD values of
Dyeing properties
Fig. 4 illustrates the relative colour strength of dyed
Fig. 3. Affection of polar and unpolar solvents on lmax
of synthesized dye.
Fig. 2. Dyeing curve of PET fabric with synthesized
dye.
Fig. 4. Build-up curve of synthesized dye.
J. Chin. Chem. Soc. 2013, 60, 351-354
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Article
Dodangeh et al.
Table 1. Colour fastness of dyed PET fabric
Table 2. COD of the dye solution and different wastewaters
Uncleared
Staining
Change
Staining
Change
Staining
Change
4
4-5
5
Characteristics
COD (mg l -1)
Dye solution
39999
786.66
510
Alkali cleared
Reduction cleared
Dying bath waste water
5
Reduction clearing bath waste water
Alkali clearing bath waste water
5
293.33
5
Light fastness
Heat Fastness
(150 °C)
5-6
4-5
treatment.13-15 Furthermore, it is assumed that minimizing
the need for reduction clearing can lead to improvements in
substantial productivity, water and chemical savings as
well as a reduction of the effluent load and it should be a
key objective in the implementation of a Rapid Dyeing ap-
proach to PET. The dye applied to PET fabric produced or-
ange hue and showed high build-up properties. The fast-
ness properties of synthesized disperse dye on PET fabric
were excellent. This alkali-clearable dye is easily removed
by alkali addition in dye bath. Therefore, the expenditure of
the production process decreased. These results indicate
that dyes containing a carboxyl structure offer better wash
fastness than conventional disperse dyes on PET and ulti-
mately, an alkali-clearing process can be used instead of
reduction-clearing just as effectively and lead to decrease
value of biological oxygen demand (BOD) and subse-
quently reduction in water pollution.
the dye solution and the resulting wastewaters from dyeing,
reduction clearing and alkali clearing processes are com-
pared in Table 2.
The results indicated that lower COD value was
achieved under alkali clearing process. When the conven-
tional reduction clearing process is applied to azo disperse
dyes, the azo linkage is broken and, as the case maybe, car-
cinogenic aromatic amines are liberated into the efflu-
ent.10-12 Therefore, the synthesized dye offers a mild alka-
line condition instead of reduction clearing process to elim-
inate surface dye molecules which leads to less polluted
wastewater.
CONCLUSIONS
Azo disperse dyes incorporating a carboxylic group
hydrolyzed under relatively mild alkaline conditions and
temperatures. A novel mono azo disperse dye containing a
carboxylic group was prepared at a weak alkali pH from p-
amino benzoic acid considered as the diazo component and
b-naphthyl acetate as the coupling component. Since dis-
perse dyes have a limited solubility in water, some particu-
late disperse dye molecules may still be occluded on the fi-
bre surface after the dyeing is completed. If these are not re-
moved, the surface contamination can undermine the
brightness of shade as well as the wash, sublimation and
rubbing fastness. The usual treatment undertaken is reduc-
tion clearing, in this case the dyed fabric is treated in a
strong reduction bath, usually made up of sodium hydro-
sulphite and caustic soda.5 However, the conventional re-
duction clearing process in case of azo disperse dyes, has
the potential of generating aromatic amines liberated into
the effluents and creates an environmentally ineligible
wastewaters with high COD values. Alkali-clearable dis-
perse dyes obviated the need for sodium hydrosulphite and
significantly reduced the COD and the cost of effluent
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J. Chin. Chem. Soc. 2013, 60, 351-354