Full text of DOI:10.1111/j.1478-4408.2003.tb00153.x

Towards a universal dye class for printing
on multiple substrates
Coloration
Technology
D Hinks,* M Rashad and A El-Shafei
Department of Textile Engineering, Chemistry and Science, North Carolina State
University, PO Box 8301, Raleigh, NC 27695, USA
Email: david_hinks@ncsu.edu
Received: 9 October 2002; Accepted 17 December 2002
Society of Dyers and Colourists
Textile printing using dyes requires different dye classes to be used for different substrates, which
increases complexity in the printing operation. The development of a single (universal) class of dyes
that can be applied to all fibres to produce prints with excellent technical properties is desirable.
Reported is one approach to a universal dye class for printing on multiple substrates. A temporarily
water soluble fibre-reactive dye, 2-[(4-{(E)-[4-(diethylamino)phenyl]diazenyl}phenyl)sulphonyl]ethyl
sodium sulphate, was synthesised and printed on cotton, polyester, polyester/cotton blend, wool,
nylon and acrylic fabrics. A print–dry–cure process was employed. Bright, level prints with high colour
strength, good rub fastness and fair to good wash fastness were obtained for all substrates except
acrylic, which did not produce good prints. However, significant amounts of unfixed dye were
removed during soaping.
Introduction
different lighting or observer conditions. As the fibres are
often intimately blended, the net result will be a perceived
colour inconstancy of the blended fabric when viewed under
different light sources, which will be more difficult to
minimise than if only one dye or print recipe was employed.
If the same dyes could be used to dye or print the two fibres
in a blend the result would be a non metameric match since
the reflectance curves would be the same or very similar.
Clearly, the development of a method to enable multiple
substrates to be dyed or printed by one class of dye is
desirable. One approach is to derivatise fibres to modify
their properties, e.g. by reacting colourless hydrophobic
groups onto cotton or wool to make the fibre substantive
towards disperse dyes [5,6]. Another approach is the
development of a new class of dyes that can be applied to
multiple substrates using a simple procedure. The dyes in
such a class can be referred to as ‘universal dyes’. Using
only one dye class would ensure the number of dyes
employed by the dyer/printer could be kept to a minimum,
thereby reducing complexity in coloration technology,
management and effluent treatment. Furthermore, since the
dyestuff manufacturing industry for textiles is now a
mature industry, the cost of development of a new class of
dyes is considered high risk, particularly in regard to
toxicity and environmental impact. The development of
such a class of dyes that can be applied to many substrates,
therefore, means that the total potential market is much
larger than the conventional approach of one dye class for
one substrate. For instance, the market potential for
dyestuff application to polyester (34%), cotton (39%), nylon
(7%) and wool (3%) is approximately 83%, or approx-
imately 40 million tonnes, of all major fibres produced [7].
Printing of textile substrates can be undertaken using
pigments or dyes. Pigments can be applied to any substrate,
but require a binder to mechanically entrap the pigment
particles onto the surface of the substrate [1]. Consequently,
the fabric handle is affected and rub fastness can be inferior
to other coloration methods. Dyes, on the other hand, are
soluble in the medium in which they are applied and are
designed to diffuse into the substrate. However, in order to
obtain optimised technical properties, such as dye build-
up and wash and light fastness, different classes of dyes
have been developed for application to specific substrates
[2–4]. Thus, significant complexity exists in dyehouse
management, especially in the case of printing fibre blends
with dyes. For instance, dyeing or printing polyester–cotton
fabric requires disperse dyes to dye the polyester and fibre-
reactive, direct or vat dyes to dye the cotton. Hence, dyers
and printers that use multiple substrates commonly stock
a large number of dyes. Furthermore, environmental
legislation limiting the release of dyes into waste streams
means that treating highly variable dyebath effluent is also
complex and reduction of the levels of colour in the effluent
can be problematic.
Dye recipe formulation, and specifically metamerism,
is also an issue in the dyeing or printing of fibre blends.
As the dyes used to colour one fibre in a blend will be
different to those used to colour the other fibre, different
recipes are of course required for each substrate, which in
turn produces disparate reflectance curves on each coloured
substrate resulting in a metameric match. Hence, the two
fibres may only match for one light source, and significant
variation in perceived colour may be produced under
70 © Color. Technol., 119 (2003)
Web ref: 20030202

Several approaches to the development of new dye
classes that can be applied to more than one substrate have
been explored. One approach has been the development of
a cationic fibre-reactive dye system that exhibits substant-
ivity to all fibres carrying a negative charge [8,9]. The main
drawbacks to this approach are that cationic dyes exhibit,
at best, moderate light fastness on most substrates and
toxicity is a concern with organic compounds containing
quaternary ammonium salts.
Another method is the application of disperse fibre-
reactive dyes possessing a tertiary amino group that can be
protonated under mild acidic conditions [10]. Hence, water
solubility and substantivity towards anionically charged
fibres are facilitated depending on the processing
conditions employed.
A further possibility towards the development of a
universal dye class is the concept of providing a labile
water-solubilising group to a fibre-reactive dye molecule
that could be cleaved during processing. Hence, water
solubility would be facilitated temporarily since the water
solubilising group would be cleaved during application to
the fibre. Previous work in this area has focused on utilising
temporarily solubilised disperse dyes for dyeing polyester
fibres in the absence of dispersing agents [11–13]. However,
incorporation of a fibre-reactive moiety in addition to
temporary water solubility opens the prospect of dye–fibre
covalent bond formation with fibres possessing nucleo-
philic sites, such as cotton/viscose, wool [14] and polyamide.
In addition, loss of the temporary solubilising group would
produce a non-ionic disperse dye that could exhibit
substantivity for hydrophobic fibres such as polyester and
cellulose di- and tri-acetate [11].
An exhaustion dyeing system based on this approach that
produces level dyeings and satisfactory fastness properties
on multiple fibres may not be easy to produce. This is
because it would be necessary to use dyes of relatively low
molecular weight to ensure diffusion within hydrophobic
fibres, but low molecular weight anionic dyes will likely
exhibit relatively low substantivity for hydrophilic fibres,
such as cotton. A localised application method, however,
such as print–dry–cure or print–dry–steam, or a semi-
continuous process such as pad–dry–cure, in which the dye
is delivered to the surface of the substrate(s) in a concentrated
form may afford more level and fast coloured substrates.
The present work reports solid prints on cotton,
polyester–cotton blend, nylon, wool and acrylic fabric using
an azo dye [11], 2-[(4-{(E)-[4-(diethylamino)phenyl]-
diazenyl}phenyl)sulphonyl]ethyl sodium sulphate 1. The
sodium salt of a β-sulphatoethylsulphonyl moiety imparts
water solubility. As stated by Lee and Kim [11], under mild
alkaline conditions, β-elimination of the water solubilising
sulphato group occurs to produce a fibre-reactive vinyl-
sulphonyl disperse dye. Scheme 1 illustrates the mechanism
for application to multiple fibres. The dye is incorporated
into a print paste containing sodium carbonate. When
printed onto hydrophobic fibres disperse reactive dye 2
diffuses into the fibres during curing. In the case of
hydrophilic fibres containing nucleophilic groups, the alkali
in the print paste facilitates nucleophilic attack on the
vinylsulphonyl moiety to produce a covalent bond.
Experimental
Instrumentation
Proton nuclear magnetic resonance (1H NMR) spectra were
recorded using a General Electric NMR OMEGA 300.52
MHz instrument using [2H6]DMSO. Coupling constants J are
quoted in Hz. The progress of the reaction for synthesis of
1 was followed by thin layer chromatography (TLC) using
aluminium-backed silica TLC plates (240 µm, fluorescent).
An Atlas Launder-o-meter, model LHT, and an Atlas Crock
Fastness Tester, model CM-5 (Atlas Electric Device Co.,
USA) was used for wash fastness and crock fastness testing,
respectively. A Werner Mathis AG Coating Range, Type LTF
134489, was used for curing samples. A Datacolor
International (NJ, USA) Spectraflash 300, large area view,
specular included, was used for all reflectance measure-
ments of printed substrates. Colour difference (K/S) data
were calculated using the Kubelka–Munk equation, with
values at maximum wavelength (λmax) being used.
O
O
S
NaO
S
O
CH2 CH2
N
Et
Et
N
N
O
O
1
Hydrophilic
fibres
Hydrophobic
fibres
pH > 8
β-elimination
(i) Dye absorption
(ii) Nucleophilic attack
O
S
H2C CH
N
Et
Et
N
N
O
2
O
Heat
fibre
X
CH2 CH2
S
N
Et
N
N
O
Et
(i) Adsorption
(ii) Diffusion
Scheme 1
where X = O, NH, etc.
Web ref: 20030202
© Color. Technol., 119 (2003) 71

General
hydrophobic variant of the dye for application to hydro-
phobic fibres such as polyester. Furthermore, the relative
molecular weight of the dye must be sufficiently low to
enable diffusion into polyester fibres, for instance. General
technical properties such as low toxicity, acceptable light
fastness and low cost must also be considered. The sodium
salt of a β-sulphatoethylvinylsulphonyl group is a con-
venient substituent to impart temporary water solubility
while at the same time introducing a fibre-reactive group
that can undergo a Michael addition-type reaction with
nucleophiles present on a fibre, into an otherwise non-
reactive dye [11]. The fibre-reactive dye 1 satisfies these
basic criteria, and was therefore synthesised using a
conventional concentrated hydrochloric acid diazotisation
method, followed by washing with brine. Diazotisation
using a relatively concentrated acid produced significantly
higher yields than a dilute hydrochloric acid method
reported by previous workers [11]. No further purification
All fabrics were scoured and purchased from TestFabrics,
Inc., New Jersey, USA: 100% bleached cotton knit jersey;
50:50 polyester/bleached cotton knit; 100% polyester knit;
100% acrylic knit; and 100% nylon 6.6. All chemicals
were analytical grade and purchased from Aldrich
Chemical, USA.
Synthesis of compound 1
4-Aminophenyl-β-sulphatoethylsulphone (5.0 g of 96%;
0.018 mol) was dispersed in concentrated hydrochloric acid
(19.0 ml; 0.18 mol) followed by the slow addition of water
(40 ml) with cooling to < 5 °C with vigorous stirring. To this
dispersion was added dropwise 2 M sodium nitrite (9.1 g;
0.018 mol) and after 2 h, excess nitrite was destroyed by
addition of sulphamic acid. The diazo solution was then
added dropwise to a solution of N,N-diethylaniline (2.83 g;
0.019 mol) in 40 ml of water at 0–5 °C. After 5 h, the pH of
the deep red reaction mixture was raised to 3 by slow
addition of 2 M sodium carbonate solution, and sodium
acetate (3 g) was added. The mixture was stirred for a further
2 h, filtered, washed with brine and dried in a desiccator
overnight, giving the final product of 2-[(4-{(E)-[4-(diethyl-
amino)phenyl]diazenyl}phenyl)sulphonyl]ethyl sodium
sulphate 1 (6.50 g; 84.4% of theory). TLC of the product gave
one orange–red spot (Rf = 0.75; isopropanol/ethyl acetate,
6:4). The structure of the compound was characterised by
1
was required as TLC showed only one spot and H NMR
analysis showed a clean spectrum with all peaks of the title
compound assigned, although it is likely that small residues
of salt were present following the brine wash.
The primary goal of the work was not to develop a fully
optimised printing method for each substrate, but rather
to demonstrate the concept and scope of a universal dye
system via the proposed approach. A simple silk screen was
used to produce solid prints on each substrate. Minimal
auxiliaries were incorporated into the print paste. The
following variables were studied: dye and alkali concen-
tration, cure temperature and cure time. Wash fastness and
rub fastness were selected as key performance measures
to assess whether the dye had penetrated and fixed on the
substrates.
NMR: δH([2H6]DMSO)/ppm 7.8–8.05 (6H, m, J 7.34), 6.85
3
(2H, d, 3J 7.34), 3.95 (2H, t, 2J 11, 3J 6.6), 3.65 (4H, q, 2J 10.73,
3J 5.86), 3.5 (2H, t, 3J 5.86), 1.15 (6H, t, 2J 11.74, 3J 5.87).
Printing method
Unless otherwise stated, a print paste was made using 5 g/
kg dye, 100 g/kg urea, 600 g/kg sodium alginate (4% w/w
solution), 5 g/kg sodium carbonate and 250 ml water. A 20
× 10 cm silk screen with squeegee was used for all
printing. Printed samples were dried at 60 °C for 10 min
and cured at 160 °C for 5 min. Each print was washed with
hot and cold water and soaped three times using 2 g/l
Apollo Scour SDRS at 80 °C for 5 min and dried in air.
Optimising the colour yield of the printed fabrics
Figure 1 shows the plot of colour yield against wavelength
using 5 g/kg dye for each printed substrate after repeated
soaping in non-ionic detergent. The results show that very
bright prints with high colour strength were afforded when
nylon 6.6 was used, whereas pale prints were produced on
acrylic. The prints obtained with each of the other sub-
strates studied were comparable to each other, although the
λmax shifted slightly in the case of cotton and wool,
indicating possible aggregation effects. However, very level
prints were produced in each case.
Fastness testing
Wash fastness testing was conducted according to AATCC
Test Method 61-1996 [15] and rub fastness testing was
performed using AATCC Test Method 8-1995 [16].
20
Results and Discussion
Cotton
Polyester
Poly/cotton
Nylon
Wool
Acrylic
A print application was chosen for this initial work for
several reasons. In addition to the possibility that a
concentrated application and cure method will produce a
high degree of levelness and facilitate high fixation, the
development of low effluent coloration processes is
currently receiving greater emphasis due to environmental
legislation and high cost of effluent treatment. Furthermore,
a successful basic print application may lead to the
development of a universal ink-jet printing process for
textile and paper substrates.
16
12
8
4
0
A successful universal dye requires certain chemical
properties to be designed in to the molecule. Water sol-
ubility is a requirement for application to hydrophilic fibres
such as cotton, but it must also be possible to produce a
400
460
520
580
640
700
λ
, nm
Figure 1 K/S spectra for dye 1 printed on various substrates
72 © Color. Technol., 119 (2003)
Web ref: 20030202

In order to ensure maximum fixation in the case of fibres
possessing nucleophilic groups, or diffusion in the case of
hydrophobic fibres, the printed fabrics required curing.
The cure temperature was assessed from 80–160 °C using
5 g/kg dye and 5 g/kg sodium carbonate. Figure 2 shows
the effect of cure temperature on colour strength. Each print
was rinsed with hot and cold water and soaped three times
to remove residual dye. In all cases, K/S increased with
increasing cure temperature. A cure temperature of 160 °C
was selected as the most appropriate condition for the study
of other variables. The disparity in colour strength for each
substrate is clearly evident from Figure 2, with prints on
acrylic affording weak colours and polyester, nylon and
wool exhibiting the highest colour strength.
Using 160 °C as the cure temperature, the curing time
was then assessed. As shown in Figure 3, curing for at least
5 min is required to maximise the colour strength. The
importance of curing for all substrates is demonstrated by
t = 0 in Figure 3, where the majority of dye applied was
washed off in all cases, as indicated in the low K/S values.
The curing step facilitates the diffusion of dye from the
surface to the interior of the fibres and, in the case of fibres
possessing nucleophilic groups, reaction between the
vinylsulphonyl group and the substrate.
Perhaps the most important step in the application of
dye 1 is elimination of the β-sulphatoethylsulphonyl group
to produce disperse reactive dye 2. Elimination occurs
under mild alkaline conditions and at low temperatures
[3,11]. However, in the case of cotton and cotton blends,
primary hydroxy groups necessarily require ionisation to
facilitate nucleophilic attack. Hence, high pH is required
for dye–fibre reaction to take place. Using a cure temp-
erature of 160 °C for 5 min, the effect of sodium carbonate
concentration on K/S values at λmax after repeated rinsing
and soaping was assessed. Figure 4 shows the colour yield
data for each substrate before and after soaping. The
requirement for alkalinity is clearly evident from the con-
trol prints where no sodium carbonate was added to the
print paste. In all cases, an increase in both dye uptake and
fixation was observed under alkaline conditions. It is also
evident that approximately 10–20% of dye was removed
during the multiple soaping stages demonstrating that the
reaction and/or diffusion was incomplete. Nevertheless, in
the case of cotton, polyester and wool, relatively high dye
uptake and fixation was afforded using 5 g/kg sodium
carbonate. In addition, bright and level prints were
afforded. Hence, this concentration was employed for
studying wash and rub fastness properties.
25
Cotton
Polyester
Poly/cotton
20
Fastness testing of the printed fabrics
Nylon
Wool
After repeated soaping, a standard wash test at 60 °C was
employed on each printed fabric using the selected
conditions described above and the colour changes were
as follows: cotton, 3; polyester, 4–5; polyester/cotton, 4;
acrylic, 3; nylon 6.6, 1–2; and wool, 2–3. These results show
that additional dye was removed from each substrate
during the wash test, and the colour fastness due to
washing was surprisingly poor in the case of nylon 6.6, fair
for cotton and polyester/cotton blend and good for polyester.
The significant change in colour in the case of nylon 6.6 is
due, in part, to the very high colour strength produced from
the prints and a proportionally large amount of dye that
was removed from the substrate relative to other fibres.
Colour change to washing for acrylic was fair, except that
the prints were low in colour strength prior to washing.
Clearly, not all the dye was fixed onto each fibre using
the application conditions employed. Nevertheless, in
almost all cases, level, bright prints with high colour
strength remained after the standard wash test was
performed. The addition of multi-fibre strips during the
wash test afforded analysis of staining on adjacent fibres.
Table 1 shows a summary of the staining data.
15
Acrylic
10
5
0
80
100
120
Temperature, o
140
160
C
Figure 2 Effect of cure temperature on colour strength of
various substrates printed with dye 1
25
20
15
10
5
In the case of cotton, significant staining was recorded
on nylon, silk and wool, whereas the prints on polyester
and wool exhibited little staining on any adjacent fibre.
Also, heavy staining was observed from the wash test of
the printed acrylic fabric, indicating that the dye present
was mainly on the fabric surface.
Interestingly, standard wet and dry rub fastness testing
on each printed substrate following application of 5 g/kg
dye and curing at 160 °C for 5 min were good to excellent
in all cases, as indicated in Table 2. In general, therefore,
as is the case for conventional fibre-reactive dyes on cotton
0
0
1
3
5
7
Time, min
Figure 3 Effect of cure time on colour strength of various
substrates printed with dye 1; for key see Figure 2
Web ref: 20030202
© Color. Technol., 119 (2003) 73

Cotton
Polyester
10
8
14
12
10
8
(a)
(b)
6
6
4
4
2
2
0
0
0
5
10
20
40
0
5
10
20
40
Sodium carbonate, g/kg
Sodium carbonate, g/kg
Polyester/cotton
Nylon
12
10
8
20
15
10
5
(c)
(d)
6
4
2
0
0
0
5
10
20
40
0
5
10
20
40
Sodium carbonate, g/kg
Sodium carbonate, g/kg
Wool
Acrylic
20
15
10
5
4
3
2
1
0
(e)
(f)
0
0
5
10
20
40
0
5
10
20
40
Sodium carbonate, g/kg
Sodium carbonate, g/kg
Before soaping
After soaping
Figure 4 Effect of sodium carbonate concentration on colour strength and fastness to soaping of various substrates printed with dye 1
and wool, the present dye does not produce dyeings with
100% fixation using the application conditions employed.
However, in each case a significant level of surface dye was
not present as indicated by the rub fastness data.
It is possible that a two-step process in which dye is
printed under neutral or slightly acidic pH followed by
application of alkali would yield better dye fixation in the
case of cotton. Also, a steaming procedure in lieu of a dry
heat cure may improve fixation for some substrates.
Additional optimisation of the application conditions for
each substrate may improve the fixation efficiency, in
which case an investigation into the potential utility of the
74 © Color. Technol., 119 (2003)
Web ref: 20030202

Table 1 Staining of adjacent multi-fibre following wash fastness dataa
Substrate
Adjacent multi-fibre
Cotton
PETb
PET/cotton
Acrylic
Nylon
Wool
Acetate
Modacrylic
4
5
4–5
5
4
5
3–5
5
3–5
5
4
5
Triacetate
Cotton
Acrylic
4–5
5
5
5
5
5
4–5
5
5
4
5
5
4
5
5
5
3–5
5
Dispersible dyeable PET
Basic dyeable PET
Nylon 6.6
4–5
4
3
5
5
4–5
5
5
4–5
4
4–5
4
3–5
5
5
4–5
5
5
4–5
3–5
5
Orlon 75
5
5
5
Spun silk
3
4
3–5
2–5
3
5
Polypropylene
Viscose
Wool
4–5
5
3
5
5
4–5
5
5
4
5
5
2
5
5
3
4–5
5
4
a Print conditions: 5 g/kg dye, 100 g/kg urea, 600 g/kg sodium alginate (4%), 5 g/kg sodium carbonate, dry
60 °C for 10 min, cure 160 °C
b
PET = polyester
Table 2 Standard wet and dry rub fastness data [16]
amounts of unfixed dye were extracted during soaping and
a standard wash test, although rub fastness data were good
to excellent.
Rub fastness data
Substrate
Wet
Dry
References
1. H Gutjahr and R R Koch, in Textile Printing, 2nd Edn, Ed. L
Cotton
4
5
4–5
4–5
5
4
4–5
5
4–5
5
4–5
W C Miles (Bradford: SDC, 1994) 139.
2. C H Giles, in The Theory of Coloration of Textiles, 2nd Edn,
Ed. A Johnson (Bradford: SDC, 1989) 97.
Polyester
Polyester/cotton
Acrylic
Nylon
Wool
3. P Rhys and H Zollinger, in The Theory of Coloration of
Textiles, 2nd Edn, Ed. A Johnson (Bradford: SDC, 1989) 428.
4. R M Christie, Colour Chemistry (Cambridge: RSC, 2000).
5. D M Lewis and P J Broadbent, J.S.D.C., 113 (1997) 113.
6. H Wang and D M Lewis, Color. Technol., 118 (2002) 159.
7. W Schrott, Melliand Textilber., 6 (2001) 514.
8. D Hinks, Cationic reactive dyes for cellulosic and polyamide
fibres, PhD Thesis, University of Leeds (1993).
9. D Hinks, S M Burkinshaw, D M Lewis and A H M Renfrew,
Text. Chem. Colorist, 1 (5) (2001) 43.
10. P Suwanruji, Synthesis of a Universal Dye for Textile Fibers,
MSc Thesis, North Carolina State University (2000).
11. W J Lee and J P Kim, J.S.D.C., 115 (1999) 270.
12. W J Lee and J P Kim, J.S.D.C., 115 (1999) 370.
13. J J Lee, N K Han, W J Lee, J H Choi and J P Kim, Color.
Technol., 118 (2002) 154.
4–5
approach to ink-jet printing of textile substrates would be
warranted. In this case, a two-step process in which the
water-soluble dye and the alkali are printed separately
would be required.
Conclusions
It has been shown that a temporarily solubilised fibre-
reactive dye of type 1 can be applied to multiple substrates
to produce level and bright shades on cotton, polyester,
polyester/cotton blend, wool and nylon. Prints on acrylic
using the developed method were poor quality. Significant
14. W J Lee, W H Choi and J P Kim, Color. Technol., 117 (2001)
212.
15. AATCC Test Method 61-1996, AATCC Technical Manual, 76
(2001).
16. AATCC Test Method 8-1995, AATCC Technical Manual, 76
(2001).
Web ref: 20030202
© Color. Technol., 119 (2003) 75