Post on 03-Mar-2023
Method to achieve
print-bake fixation for
inkjet printing of dyes
A dissertation submitted to The University of
Manchester for the Master of Philosophy in the Faculty
of Engineering Physical Sciences
2015
Renwei Tian
School of Materials
University of Manchester
1
Contents List of figures ................................................................................................................. 3
List of tables ................................................................................................................... 5
ABSTRACT ................................................................................................................... 6
DECLARATION ........................................................................................................... 7
ACKNOWLEDGEMENT ............................................................................................. 8
COPYRIGHT STATEMENT ........................................................................................ 9
1. Introduction .............................................................................................................. 11
1.1 Literature review ................................................................................................ 12
1.1.1 Cotton .......................................................................................................... 12
1.1.2 Historical background of reactive dye ......................................................... 24
1.2 Research purposes .............................................................................................. 48
2. Research Methodology ............................................................................................ 50
2.1 Convert commercial dye (MX-2G Blue) to phosphonic acid containing dye .... 50
2.1.1 Synthesis of Dye 1 ....................................................................................... 50
2.1.2 Synthesis of Dye 2 ....................................................................................... 57
2.1.3 Synthesis of Dye 3 ....................................................................................... 60
2.2 Application of modified dye to cotton ............................................................... 61
2.2.1 Pad-batch method ........................................................................................ 61
2.2.2 Inkjet printing via modified dye .................................................................. 66
2.3 Inkjet printing via Desktop inkjet printer ........................................................... 71
2.3.1 Pre-treatment of cotton fabrics .................................................................... 73
2.3.2 Desktop inkjet printing process ................................................................... 74
3 Evaluate modified dye performance ......................................................................... 76
3.1 Colour strength measurement for inkjet printed sample fabrics via
spectrophotometer .................................................................................................... 76
3.1.1 Measure samples.......................................................................................... 77
3.2 Tensile Test ........................................................................................................ 78
2
3.2.1 Tensile Procedure ........................................................................................ 80
3.3 Ultraviolet-Visible spectrophotometry ............................................................... 81
3.3.1 Sample measurement ................................................................................... 82
3.3.2 Standard solution make up .......................................................................... 84
3.4 Fourier Transform Infrared Spectroscopy .......................................................... 85
3.4.1 FT-IR measuring procedure......................................................................... 86
3.5 Thin layer chromatography ................................................................................ 87
3.5.1 Producing the chromatogram ....................................................................... 89
3.5.2 Rf Values ..................................................................................................... 92
4 Results and Discussion ............................................................................................. 94
4.1 Dye analysis ....................................................................................................... 94
4.1.1 Thin layer chromatography ......................................................................... 94
4.1.2 FT-IR ........................................................................................................... 97
4.2 Application of synthesised phosphonic acid containing dye to cotton .............. 98
4.2.1 Effect of Catalyst type and Concentration on dye fixation via Pad-bake
method .................................................................................................................. 98
4.2.2 Effect of Catalyst type and Concentration on dye fixation via Inkjet printing
............................................................................................................................ 108
4.2.3 Effect of printing method on colour strength ............................................ 112
4.3 Effect of pretreatment and baking process on tensile strength ......................... 118
5. Conclusion ............................................................................................................. 122
5.1 Recommendations for future research.............................................................. 125
5.2 Future of Inkjet printing ................................................................................... 126
6. Reference ............................................................................................................... 127
7. Appendix…………………………………………………………………………137
3
List of figures
Figure.1.1 Cotton boll after opening
(https://oecotextiles.wordpress.com/tag/cotton-boll/) ................................... 13
Figure 1.2 Cross-sectional view of a cotton fibre (Textile Fibers, © 2013 Cotton
Incorporated). ................................................................................................ 14
Figure 1.3 Longitudinal convolutions of a cotton fibre (Plant Fibres for Textile
and Technical Applications, 2013) ................................................................ 15
Figure 1.4 Cross-sectional view of a bundle of cotton fibres (Plant Fibres for
Textile and Technical Applications, 2013) .................................................... 16
Figure 1.5 D-configuration glucose unit (Journal of Biomaterials and
Nanobiotechnology, 2013) ............................................................................ 18
Figure 1.6 β-(1-4) glycosidic bond (Identification of a chemical indicator of the
rupture of 1,4-β-glycosidic bonds of cellulose in an oil-impregnated
insulating paper system. 2007) ..................................................................... 18
Figure 1.7 cellulose molecules chain
(http://staff.concord.org/~btinker/workbench_web/unitIV_revised/cellulose/
cellulose6.html) ............................................................................................. 19
Figure 1.8 The structure and the inter- and intra-chain hydrogen bonding pattern
in cellulose. ................................................................................................... 20
Figure 1.9 Positions in the cellulose structure for chemical reactions. (Recent
developments in spectroscopic and chemical characterization of cellulose . 21
Figure 1.10 Configurations of the crystalline and amorphous regions in cellulose
microfibril. (Cellulose nanomaterials review: structure, .............................. 21
Figure 1.11 Unit cells for cellulose structures Iα (a). (Parallel-up structure ......... 22
Figure 1.12 Unit cells for cellulose structures Iβ (b). ((Parallel-up structure ....... 23
Figure 1.13 Relative configuration of Ia with respect to Iβunit cell
(Macromolecules, 1991) ............................................................................... 23
Figure 1.14 The components of a Reactive dye. (The dyeing of textile fibres,
1992) ............................................................................................................. 25
4
Figure 1.15 Procion Indigo Navy MX-2G
(http://www.worlddyevariety.com/reactive-dyes/reactive-blue-109.html) ... 26
Figure 1.16 Nucleophilic substitution for reactive dye (The dyeing of textile
fibres, 1992) .................................................................................................. 27
Figure 1.17 2-Bowl padder mangle (http://www.indiantextilejournal.com) ......... 31
Figure 1.18 Textile Printing by Conventional Manual Methods .......................... 33
Figure 1.19 Textile Printing by Inkjet printing Methods ...................................... 34
Figure 1.20 Formation of droplet (Textile digital printing technology, 2005) ...... 36
Figure 1.21 Formation of droplet (www.huntsman.com) ..................................... 37
Figure 1.22 Unfixed dye test (The Surface Designer's Handbook,2006) .......... 39
Figure 1.23 Reactive dyeing effluents emission
(http://news.cnhubei.com/xw/gn/201302/t2464886.shtml) .......................... 41
Figure 1.24 Treatment of the effluents (http://www.thermaxindia.com) .............. 42
Figure 1.25 Phosphonic acid derivative react with cellulose ................................ 44
Figure 1.26 Synthesis of Procion T dyes .............................................................. 44
Figure 1.27 Iso-urea .............................................................................................. 45
Figure 1.28 Phosphonic acid anhydride ................................................................ 45
Figure 1.29 Formation of the phosphonic anhydride ............................................ 46
Figure 1.30 Cationic adduct generated by dye phosphonate and react with cotton
....................................................................................................................... 46
Figure 1.31 Monophosphonic acid 1 .................................................................... 47
Figure 1.32 Diphosphonic acid derivative 2 ......................................................... 47
Figure 1.34 Fixation to cellulose and hydrolysis of the dye. ................................ 48
5
List of tables
Table 1.1 Average cotton fibers chemical composition (STRUCTURE AND
ENGINEERING OF CELLULOSES, 2010) ................................................. 17
Table 1.25 The fixation (%) yield of reactive dyes (The Chemistry Of Synthetic
Dyes, 1996) .................................................................................................... 40
Table 3 Standard solution concentration at corresponding Absorbance. ............ 100
Table 4 Absorbance at the wavelength of strongest absorption for wash off
solutions (not batched) ................................................................................. 101
Table 5 Absorbance at the wavelength of strongest absorption for wash off
solutions (batched) ....................................................................................... 101
Table 6 Concentration for wash off solution (not batched) ................................ 102
Table 7 Concentration for wash off solution (batched)....................................... 102
Table 8 Volume measurement for not batched sample wash off solutions ......... 103
Table 9 Volume measurement for batched sample wash off solutions ............... 103
Table 10 Dye being existed in wash off solution (not batched samples) ............ 104
Table 11 Dye being existed in wash off solution (batched samples) .................. 104
Table 12 Dye fixation for not batched samples .................................................. 105
Table 13 Dye fixation for batched samples ......................................................... 105
Table 14 Lightness and total colour difference for inkjet printing samples treated
with Cyanamide ........................................................................................... 108
Table 15 Lightness and total colour difference for inkjet printing samples treated
with Dicyandiamide ..................................................................................... 108
6
ABSTRACT
Inkjet printing is predicted as the future for printed textiles. Currently,
two main types of colourants exist: dyes, which require extensive
post-processing washing treatments but result in substrates with unaltered
handle properties; and pigments, which are economically attractive due to
their print-dry-sell application sequence, but result in textiles with
drastically altered handle.
This project proposes to investigate the use of phosphonic acid reactive
dyes for application to cellulosic substrates via inkjet printing.
It is proposed that these dyes may be fixed by dry heat, and may result in
levels of fixation sufficiently high to negate the need for washing
procedures. This project aims to test these hypotheses.
7
DECLARATION
I hereby declare that this thesis is my own work and that, to the best of
my knowledge and belief, it reproduces no material previously published
or written, nor material that has been accepted for the award of any other
degree or diploma, except where due acknowledgement had been made in
the text.
8
ACKNOWLEDGEMENT
First and foremost, I would like to express my sincerest gratitude to my
supervisor, Dr. Muriel Rigout, for her patient guidance, immense
knowledge, enthusiastic encouragement and useful critiques of this
research work. I attribute the level of my MPhil degree to her
encouragement and effort and without her this project would not have
been completed. The words are inadequate to express my feeling to Dr.
Muriel, who expended her youth and knowledge to let me raise my head
among the educated people.
Thanks also to all members of the School of Materials for their support
whenever needed, in particular, valuable assistances rendered by Dr. Huw
Owens, Mr. Philip Cohen, Mr. Adrian Handley, for training and
introducing me to the world of coloration, offering me the resources in
running the program, helping me with the testing and being friendly,
helpful, making the Lab a pleasant place to work.
I would also like to extend my thanks to all my good friends, who were
always willing to help and give support. It would have been a lonely life
in Manchester without them.
Finally, I wish to thank the two unbreakable shields, who have stood
against destructive storms for my sake, who have offered all they could
have like burning candles lighting up the path of my life, who are my
parents, I appreciate all they have done for me.
9
COPYRIGHT STATEMENT
The author of this dissertation (including any appendices and/or
schedules to this dissertation) owns any copyright in it (the ―Copyright‖)
and s/he has given The University of Manchester the right to use such
Copyright for any administrative, promotional, educational and/or
teaching purposes.
Copies of this dissertation, either in full or in extracts, may be made only
in accordance with the regulations of the John Rylands University Library
of Manchester. Details of these regulations may be obtained from the
Librarian. This page must form part of any such copies made.
The ownership of any patents, designs, trade marks and any and all other
intellectual property rights except for the Copyright (the ―Intellectual
Property Rights‖) and any reproductions of copyright works, for example
graphs and tables (―Reproductions‖), which may be described in this
dissertation, may not be owned by the author and may be owned by third
parties. Such Intellectual Property Rights and Reproductions cannot and
must not be made available for use without the prior written permission
of the owner(s) of the relevant Intellectual Property Rights and/or
Reproductions.
Further information on the conditions under which disclosure, publication
and exploitation of this dissertation, the Copyright and any Intellectual
Property Rights and/or Reproductions described in it may take place is
11
1. Introduction
Cellulosic fibres can be obtained from various parts of plants--the seed,
the stem and the leaf (Franco PHJ, Valadez-Gonzalez M, 2005). Cotton
fibre, which is harvested from the seed of the gossypium plant, is the
purest source of cellulose, with nearly 90% of the cotton fibre being
cellulose (S. Gordon and Y-L. Hsieh, 2007). This research is devoted to
the coloration of cotton fibre, the most common cellulosic fibre in textile.
Cotton has a majority share (over 50%) in the global fibre and textile
market (P. J. Wakelyn, 2007). It is a fibre obtained from the soft fibre
surrounding the seed of Gossypium, a widely grown plant in many parts
of the world. It is one of the oldest natural fibre which is still used in
today for numerous purposes. Known for its unique properties of
biodegradability, high hydrophilicity and excellent mechanical properties,
the cotton yarn may be manufactured domestically as well as industrially
manufacture (Cousey et al. 1996). There is much evidence provided by
the literature and cultural relic indicate that cotton was used in and
cultivated as early as in 3000 BC (Art Quill Studio, 2014).
Since the invention of man-made fibres, there has been a decreasing trend
in the consumption of cotton. Whereas considering cotton is an almost
inexhaustible and biodegradable source of raw material, cotton will still
have the leading share in total consumption of natural and man-made
fibres in the future.
12
Textile printing is the most universal and important method used for
introducing colour and design to textile fabrics. Considered analytically it
is a process of bringing together a design idea, one or more colorants, and
a textile substrate, using a technique for applying the colorants with some
precision (Miles, 2003).
In this research, we will investigate the use of phosphonic acid reactive
dye for application to cellulosic substrates via inkjet printing. Effects on
fixation levels, such as batching process, type and concentration of
catalyst, will be investigated. Also, assess effects of dye application on
strength retention of cotton substrate.1.1 Literature review
This section reviews relevant information related to printing of cellulosic
fibre that can be found in the literature. A brief summary of some of the
relevant concepts in cotton structure and the chemical reaction inside the
cotton and on the surface are presented in this section. Moreover, it is
necessary to look at the work that was done previously on cotton printing
with reactive dye.
1.1.1 Cotton
Cotton is obtained from the soft fibre surrounding the seed of gossypium
plants. During growth, the blossoms fall off and bolls form. There are
approximately 20 seeds inside each boll. Afterward the seed hairs (cotton
fibre) come out and begin to grow. When the growth ceases, the boll
bursts open, blooming the seed hairs (Fig 1.1). When the boll splits, the
13
moisture inside it evaporates and the wall of the fibre shrinks and
collapses. As drying proceeds, the fibre of cotton develops convolutions.
As soon as the bolls open the cotton must be picked immediately (Mather
et al. 2011).
Figure.1.1 Cotton boll after opening (https://oecotextiles.wordpress.com/tag/cotton-boll/)
1.1.1.1 The morphological structure of cotton
The cotton fibre is a single biological cell with a multilayer structure. It is
composed of four main parts, as shown on Figure 1.2; form the outside of
the fibre to the inside are cuticle, primary wall, secondary wall, and
lumen (Smole et al. 2013). During the fibre formation, the microfibrils
first stack together to from the primary wall. As the cell grows to the full
length of the fibre, secondary walls are deposited inside the primary wall
little by little, simultaneously leaving a hollow tube (lumen) at the centre
(Xiangwu Zhang, 2013).
14
Figure 1.2 Cross-sectional view of a cotton fibre (Textile Fibers, © 2013 Cotton Incorporated).
The cuticle layer is a tough protective layer covering the primary wall
with a thin waxy film, which is composed of wax and pectin materials.
More specifically, it protects the fibre from potential mechanical and
chemical damage.
The primary wall consists of numerous fibrils spiraling around the fibre
axis. Fibrils are simply packs of cellulose chains (Parker, 1998).
Chemical analysis of the primary wall indicates that it consist of some
cellulose, wax, protein and non-cellulosic substances. It is a tough
protective layer which forms during the early days of growth.
The secondary wall, which has several layers of fibrils, is also composed
of cellulose and makes up 90% of the total fibre weight. These layers of
fibrils are formed during the second growth stage. The fibrils of the
second wall are laid down together in a near-parallel arrangement. The
layers of fibrils packed in a spiral formation along its length, and reverse
in direction at regular intervals. As seen in Fig 1.3, this arrangement
15
result to each single cotton fibre having twists (convolutions) along its
length. The convolutions are very important to the longitudinal strength
and fibre-to-fibre cohesion in spun textile yarns (Cohen and Johnson,
2012). It helps the fibres interlock when it is spun into a yarn. Long fibres
have about 300 convolutions per inch and short fibres have 200 or less
(Parker, 1998).
Figure 1.3 Longitudinal convolutions of a cotton fibre
(http://ecrimescenechemistrymiller.wikispaces.com/RLG%2C+RY%2C+RW%2C+KS%2C+DH+-+7+
fibers, 2009)
The lumen is the central channel in the cotton fibre, it surrounded by the
wall. It carries nutrients of the cotton during growth and also contains the
dried residues of cell protoplasm (Parker, 1998). The lumen wall provides
the inner cell boundary (Wakelyn et al.2007).
16
The cross-section of the fibre reveals it is kidney shaped due to the cotton
fibre drying out. Specifically during drying the fibre shrinks, collapses,
and the lumens become smaller. The lumen contents evaporate after the
boll splits. After drying and collapsing of the fibre, the area of lumen is
reduced to about 5% of the total area. After bursting of the mature boll,
the fibre wall shrinks and collapses. On drying and collapsing of the fibre,
the cylindrical cross-section is converted into a convoluted ribbon form
with the flattening of the ribbon. The structure of the wall allows higher
shrinkage in the perpendicular direction to the fibrils than in the parallel
direction. Due to the spiral structure of the fibrils, the collapse results in
the twisting of the fibre about its axis.
Figure 1.4 Cross-sectional view of a bundle of cotton fibres, 2000× magnification (Plant Fibres for
Textile and Technical Applications, 2013)
1.1.1.2 Composition of cotton
As mentioned in section 1.1, the main component of cotton is cellulose.
Cotton fibre is composed of more than 90% cellulose along with wax,
17
proteins and other orangic matters (Table 1.1).
Table 1.1 Average cotton fibers chemical composition (STRUCTURE AND ENGINEERING OF
CELLULOSES, 2010)
However the composition of cotton shows a slight variation in fibre
surface and the interior of the fibre. Depending on numerous factors, such
as the environment where the cotton has been cultivated, further variation
occur (K. Stana-kleinschek et al. 1998).
1.1.1.3 Chemical structure of cotton
In simple terms, cellulose is made of repeated units of the monomer
glucose (C6H10O5), see Fig 1.5. The D configuration glucose units (so
called anhydroglucose units, AGU) are covalently linked through β-(1–4)
glycosidic linkages.
18
Two adjacent molecules linked together through
a covalent oxygen bond and C1 of one ring and
C4 of the other ring are joined through β-(1-4)
glycosidic bond (Klemm D et al. 2005), as
shown in Fig 1.6. Several hundred to over ten
thousand linked glucose units make up a linear
chain within cellulose. Since the
Figure 1.6 β-(1-4) glycosidic bond (Identification of a chemical indicator of the rupture of
1,4-β-glycosidic bonds of cellulose in an oil-impregnated insulating paper system. 2007)
-CH2OH groups are alternating above and below the plane of the
cellulose molecule, each glucose unit is rotated 180ºaround the molecular
axis, a long and close approach of neighbouring cellulose molecules
chain can be produced (Fig 1.7). Apart from this, the cellulose molecules
are able to attach close to each other because of the absence of side chains
(Maya Jacob John et al. 2008)
Figure 1.5 D-configuration
glucose unit (Journal of
Biomaterials and
Nanobiotechnology, 2013)
19
Figure 1.7 cellulose molecules chain
(http://staff.concord.org/~btinker/workbench_web/unitIV_revised/cellulose/cellulose6.html)
Each glucose residue contains three hydroxyl groups which are able to
form hydrogen bonds (inter-chain and intra-chain hydrogen bonding)
between adjoining molecules. These groups are polar, meaning the
electrons surrounding the atoms are not evenly distributed. The hydrogen
atoms of the hydroxyl groups are attracted to the oxygen atoms of the
cellulose. The intra-chain hydrogen bonding is dominated by the strong
O3-H······O5 bond (dotted line in Fig 1.6), and results in the linear
configuration of the cellulose chain (Robert J. Moon et al. 2011). The
intra-chain and inter-chain hydrogen bonding gives cellulose a relatively
stable configuration and fibrils high axial stiffness (Klemm D et al. 2005).
As seen on Fig 1.8 one primary hydroxyl group is attached at C6 and two
secondary hydroxyl groups attached at C2 and C3. These three hydroxyl
groups play an important role in causing the chains to lie together in
highly ordered structures and give rise to increasing the rigidity of the
structure of cellulose. These hydroxyl groups are also the main chemical
characteristics of cellulose which are reactive towards a variety of
20
chemicals, and this can be made use of in fibre modification, dyeing and
finishing (Gordon S et al. 2007).
Figure 1.8 The structure and the inter- and intra-chain hydrogen bonding pattern in cellulose.
Solid lines: inter- chain hydrogen bonding. Dotted lines: intra-chain hydrogen bonding (Structure,
organization, and functions of cellulose synthase complexes in higher plants, 2007)
Furthermore, these groups are hydrophilic in nature, hence giving
cellulose the native ability to bond water. Meanwhile, many types of dyes
can interact with cellulose through the hydrogen bonding with -OH
groups. For instance, reactive dye reacts with the hydroxyl groups at C6
to form a covalent bond with cellulose.
Recently research by Attala and Isogai (R. H. Attala and A. Isogai, 2005)
demonstrates that several sites within cellulose can be modified by
several kinds of reaction. As shown in Fig 1.9, different positions in the
glucose residues can enter into corresponding chemical reactions, such as
oxidation, deoxygenation, etc. In this case, we are particularly interested
in the reaction of reactive dye with cellulose which occurs via phosphoric
attached on the hydroxyl groups, especially the primary group.
21
Figure 1.9 Positions in the cellulose structure for chemical reactions. (Recent developments in
spectroscopic and chemical characterization of cellulose)
1.1.1.4 Crystal structure
The supramolecular structure of cellulose is represented by regions of low
order (amorphous regions) and high order (crystalline regions). The
degree of crystallinity of cellulose is usually in the range of 40% to 60%,
and depends on the origin of the cotton (Fink and Walenta, 1994).
Figure 1.10 Configurations of the crystalline and amorphous regions in cellulose microfibril. (Cellulose
nanomaterials review: structure,
properties and nanocomposites, 2011)
There are several polymorphs of crystalline cellulose, these are cellulose I,
II, III and IV (Moon RJ et al. 2011). The form of cellulose I is the form
found in the nature, and is the dominating form in the nature. Its structure
22
is thermodynamically less stable, hence can be converted to the most
stable structure cellulose II by treatment with aqueous sodium hydroxide
or by dissolution and precipitation of cellulose (John MJ & Thomas S,
2008). Here we focus on the structure of the cellulose I, the crystal
structure found in cotton naturally and hence that present in our samples.
Cellulose I consists of two different polymorphs: a triclinic structure (Iα)
and a monoclinic structure (Iβ), which can be found alongside each other
(Hult E-I et al. 2003). With the help of electron microbeam diffraction
and co-worked X-ray and neutron diffraction, the investigation of such
research revealed the lattice structures of each unit cell. As shown in Fig
1.11. In Iβ there are two individual chains in a lattice unit cell (Fig 1.12),
as in Iα only one chain in a triclinic cell. For Iα, the triclinic unit cell
parameters are: space group P1, a = 0.672 nm, b = 0.596 nm, c = 1.040
nm, a = 118.081º, b = 114.801º, γ = 80.3751º(Kim U-J et al. 2010).
Figure 1.11 Unit cells for cellulose structures Iα (a). (Parallel-up structure
evidences the molecular directionality during biosynthesis of bacterial cellulose, 1997)
For Iβ, the monoclinic unit cell parameters are: space group P21, a =
0.778 nm, b = 0.820 nm, c = 1.038 nm, γ= 96.5º (Kim U-J et al. 2010).
23
Figure 1.12 Unit cells for cellulose structures Iβ (b). ((Parallel-up structure
evidences the molecular directionality during biosynthesis of bacterial cellulose, 1997)
Figure 1.13 Relative configuration of Iα with respect to Iβ unit cell (Macromolecules, 1991)
The main difference between the Iα and Iβ is the relative displacement of
cellulose sheets along the hydrogen-bonded planes in the axis direction
(Fig 1.13).
Iα is a rare form, usually produced by primitive organisms, such as
bacteria, algae etc. Whereas higher plants (woody tissues, cotton etc.)
consist dominated of the Iβ form (Kim U-J, 2010). Hardy and Sarko
(1996) indicated that the Iα is metastable and can be converted into the
more stable Iβ by annealing in alkaline solution.
24
1.1.2 Historical background of reactive dye
Reactive dyes were not developed until the mid-1950s. ICI (Imperial
Chemical Industries, Ltd) launched triazinyl dyes as the first fully water
soluble reactive dye for cellulosic fibres, which could be applied to
cellulosic substrates by an exhaust dyeing process and pad fixation
process in 1956 (Rattee and Stephen, 1956). This water soluble dye forms
a dye-cellulose chemical linkage: a covalent bond. Research have shown
that one covalent bond is approximately 30 times as strong as one van der
Waals bond as 70-200 KJ mol-1
energy is required to break one covalent
bond (Lewis, 1998). Therefore the dyed substrates have very high levels
of wash fastness. The covalent bond between the dye and the cellulose
is generally only broken by hydrolysis (Arthur, 2001). Beyond that
reactive dyes, especially these used for cellulose dyeing, give a complete
range of bright colours to cotton, and provide easy means to achieve level
dyeing, which makes the reactive dye class one of the major classes of
dyes.
1.1.2.1 Typical structure of reactive dyes
A typical structure of reactive dye molecule includes:
1. The chromophoric groups (chromogen), responsible for the dye’s
colour providing properties. Its molecular structure determines the
interaction with visible light, in particular what portion of the
spectrum is absorbed. .
25
2. The reactive group (s), enabling the dye to react with the hydroxyl
groups in cellulose.
3. A bridging group, linking the reactive group(s) to the chromophoric
group(s). In this way, any change that takes place at the site of the
reactive group will have minimal effects on the colour of the dye
molecule.
4. One or more solubilising groups, attached to the chromophore,
which has the effect of improving the water solubility (John Shore,
2002).
An example of a reactive dye is C.I. Reactive Blue 5:
Figure 1.14 The components of a Reactive dye. (The dyeing of textile fibres, 1992)
The early years’ research of reactive dye indicated that depending on the
mechanism of formation of the dye-fibre bond, the reactive systems could
be classified into two categories. Those dyes containing a nitrogen
heterocyclic ring with halogeno (e.g. chlorine) substituents will carry out
nucleophilic substitution. Those dyes based on vinylsulphone reactive
26
systems function by a nucleophilic addition mechanism (John Shore,
1995). The s-triazine ring is a unique nitrogen heterocycle with three
electronegative atoms equably distributed around the ring to provide the
activation of the halogen atoms attached to the terminal carbon atoms
(Peacock, 1965). In a typical dye of this type, such as Procion Indigo
Navy MX-2G (Fig 1.15), because of the greater electronegativity of N
and Cl atoms, the 2- and 4-chloro substituents are susceptible to
nucleophilic displacement.
Figure 1.15 Procion Indigo Navy MX-2G
(http://www.worlddyevariety.com/reactive-dyes/reactive-blue-109.html)
When one of the halogen atoms is appeal to a nucleophile, which can be
either a cellulosate ion or a hydroxide ion in the case of the aqueous
dyeing process for cellulose, the remainder halogeno substituent’s
reactivity is inhibited by the new cellulosyl substituent or the new
hydroxyl substituent (Fig 1.16).
27
Figure 1.16 Nucleophilic substitution for reactive dye (The dyeing of textile fibres, 1992)
The former reaction lead to dye fixation on the fibre, the latter lead to dye
hydrolysis. This kind of dye is stable in neutral solutions, but subject to
hydrolysis under alkaline condition and autocatalytic hydrolysis on the
acid side. To keep hydrolysis from happening, a buffer is necessary to
ensure the stability during the storage and dyeing processes (J Shore,
1990).
Cellulose is not thought to be a potent nucleophile. However, in the
presence of alkali, some of the hydroxyl groups in cellulose carry out
acidic dissociation, the Cell-OH groups are encouraged to give Cell-O-
groups and it is the cellulosate ion (Cell-O-) that reacts with the dye. It is
these that the reactive dye utilises as nucleophilic site; the dye reacts with
cellulosate ion by a nucleophilic substitution mechanism. But as
mentioned earlier, the dye is susceptible to hydrolysis in alkali medium,
on account of the reactive group of the dye reacting with HO- in much the
same manner as the cellulosate ion. The hydrolysed dye reduces the
fixation efficiency and will have a lower wash fastness on the cellulose
fibre (Fig 1.17)
28
Figure 1.17 Reaction between a reactive dye and water (Colorants and Auxiliaries: Vol 1. 1990)
Nevertheless, Studies show that the reaction primarily occurs with the
cellulose fibre even though the reactive groups of the reactive dye can
react with both cellulose fibre and water. One of the reasons for this is
that the rate of the chemical reaction between cellulose and dye is much
faster than the reaction with water (100:1) as the concentration of dye in
fibre is greater than that of dye in solution. In addition, the cellulosate ion
has a greater nucleophilicity than the hydroxyl anion. Therefore, in
cellulose dyeing, most of the dye reacts with the fibre, only a small
amount of it reacts with the water (Peter J, 1977).
The dichloro-s-triazine dye is highly reactive, therefore it can readily be
fixed to cellulosic substrates by a pad-batch method at room temperature
or exhausted at 30-40ºC. For the sake of guaranteeing adequate mobility
of the reactive dye on the fibre during the exhaustion stage, relatively
small chromogens are preferred. Thus the deep tertiary hues who have
larger-size chromogens cannot give acceptable performance at low
temperature application (J Shore, 2002). These types of hues are usually
applied in less reactive forms, such as the monochloro-s-triazine type
dyes.
29
1.1.2.2 Application of reactive dye
Reactive dyes are applied to cellulosic fibres by a variety of methods,
including exhaust dyeing, pad-batch, pad-bake/steam, and
print-bake/steam. The basic principle of the dyeing process of cotton (at
the microscopic scale) can be summarized as below:
1. Adsorption of reactive dye on the surface of cotton. Salt is required
in this stage in order to compensate for the electrostatic repulsion
between the negatively charged fibre surface and the anionic dye and
considerably promote exhaustion of the dye onto the cotton.
2. Reactive dye diffuses in cotton through pores in the structure to
obtain a level distribution of dye. The diffusion depend on the
equilibrium of dye aggregated and monodispersed dye (Zollinger, H.
1991).
3. Dye fixation between cellulose and reactive dye by forming the
covalent bond. The dye molecule bonds to the cellulose fibre and
will not migrate any more.
4. Wash off unfixed and hydrolysed dye and rinse to neutral pH. Make
sure no colour will bleed from the cellulose fibre on subsequent
washing during wear and use. The amount of soap and wash off
temperature varies depending on the required wash fastness level.
1.1.2.2.1 Cold Pad-batch method
30
This is a semi-continuous method. The well prepared dry cotton fabric is
passed through a trough containing the dye solution containing required
auxiliaries (such as alkali), then wound onto the pressurised rollers of a
padding mangle, as shown in Fig 1.18. The mangle pressure is set to a
liquor pick up of typically 60-80%. Thus the cotton fabric is evenly
impregnated and the spare dye solution is uniformly squeezed. After that,
the wet fabric is wrapped in polythene film to avoid the effects of the
atmosphere on the fibre-dye reaction and stored at room temperature for a
certain amount of time (4-24 h), depending on the reactivity of the dye
selected and the pH of the impregnated fabric. This will allow better dye
diffusion and penetration into the fibre. In this research, the padded fabric
must be baked to promote further fixation. Typical baking temperatures
are between 180ºC -200ºC, and baking usually takes 1 minute. High
baking temperatures would cause fabric yellowing, and this may
influence the hue of shade. The final step is the thorough wash off
process to remove unfixed dye by rinsing with boiled soap solution.
Finally, the washed fabric is dried.
31
Figure 1.17 2-Bowl padder mangle (http://www.indiantextilejournal.com)
The cold pad-batch method offers a simple way of dyeing cotton with
reactive dyes. Under the fine control of this process (e.g. constant wet
pick-up), good and even shade reproducibility and high colour yields can
be obtained. A key problem associated with the application of reactive
dyes is the removal of the unfixed dye, which if not removed properly,
will adhere to the cellulosic fibre and will come out in subsequent
handling. As a result, a low substantivity reactive dye is favoured. This
also prevents the dye from rapidly exhausting from the dyeing solution
during the fabric passing through the trough. If this happened, the fabric
would have a deeper shade at one end than the other end. Yet because a
low substantivity dye is preferred, a considerable amount of the dye is left
in the solution. In order to achieve a high efficiency utilization of the dye,
a lower liquor ratio (amount of water required to the mass of fabric) is
preferred. The lower limit of liquor ratio in exhaust dyeing is about 5:1,
or possibly 3:1 in specially designed equipment. While Pad-batch method
can reach the range 1:1 to 0.5:1 (John Shore, 1995). This kind of
behaviour will lead to smaller amounts of water used in Cold Pad-batch
32
method, as well as help avoiding additional loss of dye through
hydrolysis. Compared to exhaust dyeing method, Cold Pad-batch process
not only save chemicals and water, but also a distinct reduction in energy
consumption can be claimed due to dyeing and fixation taking place at
room temperature. In addition, low initial investment of equipment and
the small space requirements are conspicuous advantages of the Cold
Pad-batch method.
1.1.2.2.2 Inkjet printing on cotton
Cotton printing is one of the most important and versatile techniques used
to add colour and pattern to fabrics. Namely it can be seen as the
coloration that combines design, engineering and dyeing technology to
produce specialty images on textile products.
Inkjet printing is a non-impact printing technique that permits to obtain
high quality colour images. By projecting tiny drops of liquid ink (dye
liquors) of different colours onto the cellulosic substrate, the imaged
pattern can be built up on the surface (Leslie W C Miles, 2003). The
colour is bonded with the fibre so that wash and friction resistance can be
achieved. More colours can be applied to the fabric in certain patterns,
meanwhile in dyeing process the whole fabric is dyed with one colour
uniformly.
Textile digital inkjet printing emerged in the 1990s for printing small
samples of fabric for niche-market products. The subsequent
33
developments of inkjet printing over the last decades have been dramatic.
Inkjet printing is presently growing at a rate of 13% per year, and is
predicted to grow at a rate of 20% in the following decade (Teunissen et
al. 2002). Inkjet printing is one of the fastest growing printing
technologies over the conventional printing methods. Inkjet printing
offering unique benefits such as simplicity, lower production costs,
reduced effluent, less operating skills required, lower energy and water
consumption. And beyond that, it is possible to make innovative
personalised articles. Among all the fabrics being printed, cotton takes 48%
share of the total. In inkjet printing, reactive inks are one of the most
popular inks, since the excellent water solubility, good wash fastness and
decent brightness (Ross, 2004). Going into the production time scale of a
textile print from A to Z, the considerable advantages of design selection
and sample printing with inkjet printing can be seen.
Figure 1.18 Textile Printing by Conventional Manual Methods (Textile digital printing technology,
2005)
Figure 1.19 indicates a typical time scales of those who have not adopted
digital technologies. Even with the help of CAD system and the latest
34
computer technology, the production of the sample print is still the
bottleneck. The inkjet printing technology can reduce this bottleneck
considerably by reducing the time taken for colour ways and sample
selection (Fig 1.20). Thus increases the efficiency of bring the design
concepts to the market place greatly.
Figure 1.19 Textile Printing by Inkjet printing Methods (Textile digital printing technology, 2005)
A textile inkjet printing system has the following essential elements:
1. One or more inkjet print heads, which are used to generate the
microscopic ink droplets and apply them to the substrate directly.
The types of inkjet system can be divided into two classes,
drop-on-demand (DOD) and continuous stream (CS). Over 85% of
inkjet heads are DOD type, using low viscosity water based inks and
generating drops on demand only when and where they are needed
(Chris Byrne, 2001). In this research, a DOD printer was used. So the
principles of DOD printer will be described later.
2. Inkjet inks, which majority are based on dyes due to wide shade scale
and excellent colour fastness, providing the required colour onto
35
fibres. They must be formulated with precise characterisitcs and keep
stable in ink cartridge without settling or depositing within the inkjet
nozzle.
3. A printing machine, which is used to feed and present the substrate to
the inkjet head.
4. Software, including printer drivers and colour management systems,
which control the inkjet head and machine.
5. Post treatments are necessary in inkjet printing process. Such as
baking, steaming, washing off.
6. Substrates (media) including paper, coated board, textile fabrics, etc.
Generally these substrates need pre-treatment in order to ensure
proper ink absorption and take up.
1.1.2.2.2.1 Drop-on-demand (DOD) inkjet system
In this technology, the pressure applied to the ink reservoir is not
continuous. The pressure is only applied when a droplet is needed. Two
main types of print head technologies are available in this category:
Bubble jet system
The bubble jet printer uses a small heating element in the ink reservoir to
create pressure droplets on demand. The quantity of ink in each nozzle is
heated by a resistive heating element which is controlled by the digital
data stream. The ink boils to create a bubble which forces an equivalent
36
volume of ink droplet through the jet orifice and is ejected to the fabric
surface. As shown in Figure 1.21.
Figure 1.20 Formation of droplet (Textile digital printing technology, 2005)
Based on the analysis above, this kind of technology is obviously suffered
from slow speed. Thermal/bubblejet printer is most suitable for low
volume printing. The major problem is the jet nozzle and resistance
failure rate resulting from rapid thermal cycling. The high temperature
may cause the decomposition of ink components, which leads to the
nozzle plugging. For this reason, only thermally stable inks can be used in
bubblejet printer.
1.1.2.2.2.2 Piezo jet system
This is the simplest way of producing droplets on demand. In this case,
by using Piezo electric effect, small electronic impulses delivered to
suitable crystalline materials and cause them to expand. A piezo
transducer incorporated in the ink reservoir enables pressure pulses to be
created in the ink. Droplets are generated according to the electronic
pulse intermittently. Several approaches can be used in order to turn
37
electrical signal into mechanical pressure pulses to generate ink droplets
by PZT (Pbbased Lanthanumdoped Zirconate Titanates). As shown in Fig
1.22. The jet orifice (nozzle) is required to be as close as possible to the
fabric surface so as to produce an accurate image.
Figure 1.21 Formation of droplet (www.huntsman.com)
This kind of printer has much greater print head life than the
thermal/bubblejet printer. Hence the Piezo inkjet printer is suited for high
volume printing. As the inks do not need to be heated, the components of
ink can be less critical and less expensive. And a wide range of ink
formulations can be used in this printer (Miles, 2003). Compared to
thermal/bubblejet printer, the droplet size is smaller, resulting in high
resolution.
Since cellulose printing accounts nearly 70% of all textiles printing,
considerable research has been focused on reactive dye based ink
formulations. In the last two decades, we have seen major changes in the
global textile printing market: the increasing demand for short process
run lengths, fast response, environment friendly and customisation. Also
the developing of wide format inkjet printers for small scale printing
38
production, for example, banner and sportswear, has allowed inkjet
printing to become more and more common for sample preparation and
specialised product printing (Gorgani et al. 2011).
Cotton is commonly printed with commercial reactive dye based inks due
to their excellent water solubility, high level wash fastness and brightness
of shade. The principles of dyeing cellulose as explained in section
1.1.2.1, are valid for application via inkjet printing, namely diffusion into
the fibre and chemical bond formation.
Unlike the conventional cotton printing, in which the reactive dye in the
presence of alkali in the print paste is used, the cellulosic fabrics need to
be pretreated prior to printing in the inkjet printing. The main reasons to
do this are that the reactive dye is more likely to hydrolyse in the ink
cartridge when alkali is present. Furthermore such chemicals in the
cartridge may corrode the jet nozzle; moreover, "all in" chemicals do not
have the desired rheological properties, and thus possibly block the
nozzle since the small droplets size (Aston et al. 1993). It is a common
practice for cotton fabrics to be padded with a pretreatment paste, which
is generally prepared with sodium alginate or chitosan in the presence of
sodium bicarbonate and urea (B. Glover, 2005).
After printing, two dye fixation methods can be used on inkjet printed
fabrics. For the less reactive dyes, steaming 5 to 15 minutes would be
39
necessary to obtain level fixation, depending on the steaming temperature.
Printed reactive dye can also be fixed on cellulosic fibre through baking
at 160ºC to 180 ºC for up to 3 minutes. Post treatment after printing is a
critical step, washing out the unfixed and hydrolysed dye and other
chemical residues.
However, reactive dyes, used in dyeing and printing have not largely
replaced most of the other classes of dyes for cotton. A reason for this
could be unfixed and hydrolysed reactive dye has to be removed
thoroughly in order to achieve the satisfactory wash fastness of reactive
dyeing. No matter which reactive dye is chosen or how it is processed it,
some dye will not be fixed to the fibre. The unfixed dye can be
transferred to other fabrics. To prevent bleeding, rubbing off, or back
staining of fabric during laundering, unfixed dye must be removed from
the dyed fibre.
Figure 1.22 Unfixed dye test (The Surface Designer's Handbook,2006)
This is exemplified by the test shown in Fig 1.23. In this test both fabrics
were dyed with Procion MX dyes. The fabric on the left was rinsed in
cold water only; the fabric on the right was rinsed in cold water, then
40
washed with detergent in hot water and rinsed in boiling water. A piece of
damp, undyed cotton fabric was then laid on top of each dry and dyed
fabric. Heat and pressure were applied through iron until the cotton had
dried. It can be seen that the fabric on the left had unfixed dye and stained
the undyed cotton (Holly Brackmann, 2006).
1.1.3 Environmental Footprint
According to analysis of this situation carried out by workers at
Sumitomo (Douthwaite et al. 1996.), the dye-fibre covalent bonding
efficiency of different types of reactive dyes can be identified by X-ray
fluorescence of bond sulfur before and after the washing process.
Figue 1.24 The fixation (%) yield of reactive dyes (The Chemistry Of Synthetic Dyes, 1996)
The above Figure shows in medium shade, up to 30% of the dye is
removed by the washing process, while in full shade, up to 50% of the
dye is washed away. Considering the reactive dye is highly water soluble,
it is quite difficult to separate the unfixed dye from the effluent.
It has been found that up to 50% of the total cost of a reactive dyeing
procedure has to be attributing to the wash off and after treatment of the
effluent. This limitation can be recognised as the main aspect of
41
preventing reactive dyes from dominating the dye-stuff for cellulosic
materials (Rattee and Breuer, 1994). At the end of printing, when the
cotton is washed and rinsed to remove colorant and auxiliaries, an
average of 70-150L of water is required for dyeing 1 kg of cotton with
reactive dye (Schneider, 2004).
Reactive dyeing effluents contain high concentrations of salt, hydrolysed
reactive dye from incomplete fixation, heavy metals and a variety of
dyeing auxiliaries, contributing to high BOD/COD values (Moulin et al.
2006). As seen in Fig 1.25. In addition, these effluents shows a pH of
10-11 and a high temperature (50-70ºC).
Figure 1.23 Reactive dyeing effluents emission
(http://news.cnhubei.com/xw/gn/201302/t2464886.shtml)
The large amounts of organic compounds breakdown in water can
remove all the oxygen out of rivers, resulting in killing fish and turning
the clear water into a sewer. Obviously, a proper treatment of the
effluents (Fig 1.26) is necessary and thus, adds cost. To make matters
worse, not everybody takes this step voluntarily.
42
Figure 1.24 Treatment of the effluents (http://www.thermaxindia.com)
According to an article of ―THE WALL STREET JOURNAL‖,
authorities discovered a pipe buried underneath a dyehouse floor in China
that was dumping roughly 22,000 tons of water contaminated from its
dyeing operations each day into a nearby river". Fountain Set was heavily
fined and forced to upgrade its treatment system (Jane Spencer, 2007).
Such connection is fortunately not common but may put brands at
jeopardy as well as deteriorating the environment significantly.
One third of the world population is lacking clean water, but the times of
immoderate water usage by the textile industry seem to be ending, mainly
because the price of water is higher by the day and environmental
regulation is stricter in most countries. The other reason is that in most
areas where the textile industry is established, there is not enough clean
water to use.
The textile industry, particularly the cellulose dyeing industry is
major contributor to water pollution and primary consumers of water in
the world. Millions of tons of water are consumed and contaminated with
dyes, salt, heavy metals and toxic substances of all kinds. Most of that
43
water is sent back to the environment without adequate treatment and is
harmful to the fauna and flora of rivers. Reducing the water consumption
and effluent load is not only related to the factory profit-making, but also
related to the environmental sustainability. How to get colour into
cellulosic materials with less water is the biggest issue the textile industry
is facing today. In the medium term, the textile industry has to keep
working on methods to use less water. From section 1.1.2.2, reduce the
water consumption of wash off process is a priority for all.
1.1.4 Phosphonic acid reactive dye
In 1973, researchers at the Stanford Research Institute discovered that
phosphonic acid derivatives could be induced to react with alcohols to
give phosphonate monoesters under certain circumstances. Industries
developed a new type of reactive dye based on the research of Stanford
Research Institute. This dye contained phosphonic (PO (OH)2) or
phosphoric (OPO(OH)2) acid reactive groups attached to the dye
chromophore. In 1977, ICI launched a range of reactive dyes (Procion T
dyes) for cellulosic fibres that were based on these researches. This kind
of dye had very low substantivities and was applied by the pad-dry
thermosol method at temperatures of 210-220ºC under mildly acidic
conditions (pH 5-6). These dyes generated the free phosphonic acid form
under thermofixation conditions (Fig 1.27).
44
Figure 1.25 Phosphonic acid derivative react with cellulose (Cellulose Reactive Dyes: Recent
Development and Trends, 1990)
Structures of many of Procion T dyes were based on the versatile
intermediate 3-aminophenylphosphonic acid attached to typical monoazo
chromogens in various ways (Renfrew and Taylor, 1990).
Figure 1.26 Synthesis of Procion T dyes (Cellulose Reactive Dyes: Recent Development and Trends,
1990)
An important feature of this kind of dye-fibre bond system was the
necessity to use an auxiliary for the bond formation, such as cyanamide
or dicyandiamide, as seen in Fig 1.29 and Fig 1.30.
Figure 1.29 Cyanamide
45
Figure 1.30 Dicyandiamide
The fixation mechanism can be demonstrated in terms of cellulose attack
at an iso-urea (Fig 1.31) or a phosphonic acid anhydride intermediate (Fig
1.32).
Figure 1.27 Iso-urea
Figure 1.32 Phosphonic acid anhydride
Through early studying, formation of the phosphonic anhydride was
assured to precede the esterification step (Amato et al. 1987). As shown
below.
46
Figure 1.33 Formation of the phosphonic anhydride (riazinylamino-alkylphosphonate reactive dyes for
cellulosic fibres, 2007)
An alternative mechanism enables dye phosphonate to react with
cyanamide (or dicyandiamide) to generate a cationic adduct (Fig 1.34).
Such derivative readily reacts with the cellulose fibre to form a covalent
bond.
Figure 1.28 Cationic adduct generated by dye phosphonate and react with cotton
(riazinylamino-alkylphosphonate reactive dyes for cellulosic fibres, 2007)
Typical dyes of this kind are the monophosphonic acid 1 and the
diphosphonic acid derivative 2, in which the phosphonic acid moiety is
attached directly to the aromatic ring of a diazo component, as shown in
Fig 1.35 and Fig 1.36.
47
Figure 1.29 Monophosphonic acid 1 (New Phosphonic Acid Reactive Dyes for Cotton, 1987)
Figure 1.30 Diphosphonic acid derivative 2 (New Phosphonic Acid Reactive Dyes for Cotton, 1987)
1.1.5 Reactive dyes in inkjet printing
As described in section 1.1.2.3, this high chroma, water-soluble colorants
form a covalent bond with cellulosic fibre to produce a bright durable
colour print with excellent wash fastness.
The general process route of cotton inkjet printing is to pad the necessary
auxiliaries on the fabric before the inkjet printing stage. This is because
the auxiliary chemicals required, such as urea, alkali, cannot generally be
incorporated into the inks (Tincher et al. 1996). Details were mentioned
in section 1.1.2.2.
Then the jet nozzle would eject the designed pattern on the desired area.
Cotton inkjet printing always requires a fixation stage (heat or steam),
together with washing off the unfixed dye and excess chemicals. Fig 1.37
demonstrates the fixation mechanism. Due to the physical and chemical
48
specification of jet ink formulation (e.g. ink stability, etc.), the mono
chlorotriazine reactive dye is generally used in cotton inkjet printing.
Figure 1.31 Fixation to cellulose and hydrolysis of the dye (Cellulosic Dyeing, 1995)
As discussed section 1.1.2.2, commercial inkjet inks based on reactive
dye normally have low-to-moderate fixation properties. Hence it is
important to maximize dye fixation for technical, economic and
environment reasons.
1.2 Research purposes
Based on the literature review, generally speaking, the reactive dyes used
in printing often have an unsatisfactory degree of fixation. And in order to
achieve the high level of wash fastness, removal of the unfixed dye
thoroughly is necessary. In this case, expensive washing off process has a
serious environmental impact due to the large amounts of water and the
effluent containing hazard chemicals.
A high dye fixation (closer to 100%) of reactive dye would be a great
achievement for human beings and environment. The chemical
modification of reactive dye in order to improve their dyeability is a
49
viable route. Introducing new reactive groups to a reactive dye that may
be attracted by the anionic charges on cellulosic fibre, and as result a high
degree of dye-fibre fixation, a reduced washing off process and excellent
wash fastness.
The aim of this research was to investigate the possibility of improving
the fixation efficiency of a reactive dye to cellulosic fibre in inkjet
printing applications through employing reactive dyes containing
phosphonic group, in the presence of a catalyst:cyanamide and
dicyandiamide (B. L. Mcconnell et al, 1979)
In this research, three different modified dyes was designed and
synthesised by the reaction of a commercial Dichlorotriazine reactive dye
with a suitable phosphonic acid. It is proposed that these dyes may be
fixed by dry heat, and may result in levels of fixation sufficiently high to
negate the need for washing procedures. In the following steps, the
application of the synthesised dye to cotton fabric was firstly carried out
by a pad-batch-dry-bake method in university laboratory. Catalyst type
and concentration were optimised to give the maximum colour yield and
maximum fixation. Then investigated the use of synthesised phosphonic
acid reactive dyes for application to cellulosic substrates via inkjet
printing was continued. Effects of dye application on dye fixation and
strength retention of cotton substrate were assessed through scientific
instruments. All of those tasks were done by the author himself.
50
2. Research Methodology
The following up aim of this work was to formulate a reactive dye-based
ink containing the modified dye in the previous step, with the further
intension of producing a reactive inkjet print on cotton fabric. Three
phoshonic containing dyes were synthesised in this section.
Experimental Materials:
The fabric used in this study was scoured and bleached plain weave 100%
cotton.
The cotton fabric was cut in size 20cm * 20cm.
Dyestuffs:
A highly reactive dye (dichlorotriazine) was selected and used in the
study. It was applied and manufactured by Kemtex, UK, under the
commercial name Procion blue MX-2G (C.Z Reactive Blue 109).
Auxiliaries:
The following auxiliaries and chemicals were used either for pad-bake
method or for the inkjet printing on cotton.
2.1 Convert commercial dye (MX-2G Blue) to phosphonic
acid containing dye
2.1.1 Synthesis of Dye 1
In this process, commercial reactive dye MX-2G blue was modified by
chemical reactions and converted to phosphonic acid dye 1.
51
Experimental Materials:
Molecular sieves, 1, 4-dioxane, Phosphorus trichloride,
N-(hydroxymethyl)acetamide, Hydrochloric acid, distilled water.
N.B. Chemicals used in this research are laboratory-grade standard, and
supplied either by Sigma Aldrich or by BASF.
A highly reactive dye (dichlorotriazine) was selected and used in the
study. It was applied and manufactured by Kemtex, UK, under the
commercial name Procion blue MX-2G.
Equipment and instrumentation:
Fume Hood, Balance (electronic), Beakers, Pipettes, Spatula, Stirring
rods, , Weight boat, Paper towels, dropping funnel, thermometer with
quick-fit adapter, a 3-neck 250ml round-bottom flask, oil bath, hotplate,
laboratory jack, overhead-stirrer, iron stand, desiccator & vacuum pump,
100ml single neck round bottom flask, magnetic stirrer, reflux condenser,
Rotary Evaporation.
2.1.1.1 Synthetic intermediate process
In this step, an intermediate used in modify MX-2G was synthesised. As
shown in the figure below.
52
Figure 2. 1 Intermediate synthesised
Molecular sieves are crystalline aluminosilicates, which have a three
dimensional inter-connecting network. Precise and uniform pores are
spread over the surface. These pores are small enough to allow small
molecules to pass while larger molecules are not allowed. In other words,
the small molecules are adsorbed. As an example, a water molecule is
small enough to pass through the pores, so the water is retained within the
pores. Molecular sieves are often used as adsorbent for liquids, as a single
molecular sieve can adsorb water up to 22% of its own weight without
changing the solution composition (Mineral Adsorbents, 2014)
In this case, the water content of the 1, 4-dioxane solution needs to be
reduced to very low values. Molecular sieves were used to remove water
inside the solution.
Molecular sieves need to be dried in oven for 48 hrs before applying to 1,
4-dioxane solution. Evenly placed 50g of molecular sieves in a round
glass pane, laid the pane in oven at 80ºC for 48 hrs. Once the drying
procedure was complete, added the dried molecular sieves into 100ml of
53
1, 4-dioxane solution. This mixture should be operated in a bottle. As
long as the operation was complete, closed the lid and standed for 2 days.
Prepare:water bath at 20ºC , dropping funnel, thermometer with quick-fit
adapter, a 3-neck q00ml round-bottom flask, oil bath, hotplate, laboratory
jack, overhead-stirrer, iron stand
Weighted 2.7 g of distilled water in a 50ml beaker and set aside.
Weighted 15.26g of phosphorus trichloride and placed in round bottom
flask, then mixed with 15ml of dried 1, 4-dioxane. Placed the mixture in
20ºC water bath on the raised laboratory jack, clamping on the stand
ensure the flask will stay up when the water bath is removed. Following
insert the thermometer, overhead stirrer and dropping funnel.
Weighed 9.18g of N-(hydroxymethyl)acetamide in a beaker and
dissolved in 5ml 1,4-dixoane.
The solution was transferred to the closed dropping funnel. 5ml of 1,
4-dioxane was added to rinse the beaker, and added to the dropping
funnel as well.
Started the stirring of the mixed solution, make sure the temperature of
the mixture is about 20ºC at the same time.
Gently opened the tap of the dropping funnel and added the
N-(hydroxymethyl)acetamide solution slowly to the phosphorus
trichloride and 1,4-dioxane mixture. Stopped the add process when the
temperature climbed over 25ºC.
54
After added the entire N-(hydroxymethyl)acetamide solution, closed the
dropping funnel and transferred 2.7g of water to the closed funnel. Added
the water to the lower solution very slowly. After that, added 3 ml of 1,
4-dioxaneto the dropping funnel, rinsed the funnel and added quickly to
the solution on the laboratory jack.
Replaced the water bath with the hotplate. Started heating the solution to
100ºC as soon as possible. Kept an eye on the stirring status. Make sure it
worked well.
Kept the temperature at 100ºC by modifying the settings on the hotplate,
the reaction mixture was stirred at 100 ºC for 5 hours.
Then left the mixture at room temperature to cool overnight.
The following day, decanted the upper layer carefully and disposed in
waste solvent bottle with the help of a separating funnel.
Added 30ml of water to the retained solution. Shaked well and located
the solution to a distillation flask.
Fitted the flask to a rotary evaporator and evaporated the water under
reduced air pressure at roughly 60ºC.
Once the precipitate can been observed and deposited on the sides of the
flask, collected the precipitate and dried in a desiccator to constant weight.
Vacuumed the desiccator before placed the precipitate and sealed well
after the transference.
55
Prepare oil bath, 100ml single neck round bottom flask, hotplate,
magnetic stirrer, reflux condenser.
Dissolved the dried product in last step in 50ml of 10% hydrochloric acid
solution.
Deposited the flask on hotplate and connected to the reflux condenser,
heated up to the boil and refluxed for 5 hrs.
Cooled the solution in room temperature and neutralised the pH.
Figure 2. 2 Phosphorus trichloride
Figure 2. 3 N-(Hydroxymethyl)acetamide
2.1.1.2 Convert commercial dye to phosphonic acid containing dye 1
A commercial dye of Procion MX-2G Blue (Fig 2.4), which was
assumed to be 50% pure (equal parts of dye and colourless diluents), was
reacted with intermediate product synthesised in last step to form a dye
containing two phosphonic acid groups (Fig 2.5).
Commercially formulated reactive dye commonly contains in the region
of approximately equal parts of dye. Portion of non-reactive dye (i.e.
impure component generated during commercial formulation,
56
decomposition of the dye by hydrolysis during the storage) presence in
the amount of dyestuff is very common (K Venkataraman, 2012).
Previous investigations (Alexandre Paprocki et al, 2010) on purity of
commercial dye from two suppliers prove this phenomenon: Acros
(purity 63.2%) and Sigma (> 80%). In this case, the HPLC cannot give a
clear test outcome on the original dye (MX-2G) and the accurate purity
cannot obtain. From the experimental results performed by other workers,
Procion MX-2G Blue was assumed to be 50% pure to implement the
complete reaction between original and intermediate.
Figure 2. 4 MX-2G Blue dye structure
Figure 2. 5 Phosphonic acid containing dye 1
57
9.37g of the Procion MX-2G (0.0009 mol) was added to a stirred solution
of the intermediate (0.1998g, 0.0018 mol dissolved in distilled water,
500ml beaker).
Raised the temperature of the solution to 35ºC and left to stir at this
temperature for 1 hour.
Increased the temperature to 90ºC, this condition was maintained, with
stirring, for another 1 hour.
The reaction mixture was cooled to room temperature and added
concentrated hydrochloric acid until pH 1.
The blue dye precipitate was then filtered by a Buchner apparatus.
The dye was finally dried in a desiccator.
2.1.2 Synthesis of Dye 2
In this process, commercial reactive dye MX-2G blue was modified by
chemical reactions and converted to phosphonic acid dye 2.
Experimental Materials:
Dimethylolurea, Crystalline phosphorous acid, Hydrochloric acid,
distilled water.
N.B. Chemicals used in this research are laboratory-grade standard, and
supplied either by Sigma Aldrich or by BASF.
A highly reactive dye (dichlorotriazine) was selected and used in the
study. It was applied and manufactured by Kemtex, UK, under the
commercial name Procion blue MX-2G.
58
Equipment and instrumentation:
Fume Hood, Balance (electronic), Beakers, Pipettes, Spatula, Stirring
rods, , Weight boat, Paper towels, dropping funnel, thermometer with
quick-fit adapter, a 3-neck 250ml round-bottom flask, oil bath, hotplate,
laboratory jack, overhead-stirrer, iron stand, desiccator & vacuum pump,
100ml single neck round bottom flask, magnetic stirrer, reflux condenser,
Rotary Evaporation.
2.1.2.1 Synthetic intermediate process
In this step, an intermediate used in modifying commercial dye (MX-2G)
was synthesised: bis(aminomethylphosphonate), see Fig 2.6.
Figure 2.6 bis(aminomethylphosphonate)
Dispersed 1.9g of dimethylolurea in 50 ml of distilled water (100 ml
2-necked round-bottom flask).
Added 2.0g of phosphorous acid.
Slowly dropped in 3.9g of hydrochloric acid.
Placed the flask in an oil bath, fitted with condenser, thermometer and
dropping funnel, then heated to reflux.
Left to reflux for an additional hour.
59
Decanted the solution into a rotavap flask.
Evaporated some of the water with the rotavp until the solution is
concentrated.
Added ammonia solution to reach pH 7.
Added methanol to the solution until precipitation occurs.
2.1.2.2 Convert commercial dye (MX-2G Blue) to phosphonic acid
containing dye 2
The bis(aminomethylphosphonate) synthesised in last step was added to
the dye solution (MX-2G Blue) in a 500ml beaker.
Increased the temperature to 35ºC and left to stir at this temperature for 1
hour.
Then increased the temperature to 90ºC and left to stir at this temperature
for another 1 hour.
Left the solution to cool then added hydrochloric acid until pH 1.
Filtered the dye precipitate using a Buchner apparatus.
Placed the filtrate in a desiccator to dry.
Figure 2.7 Phosphonic acid containing dye 2
60
In the following padding process, the synthesised Dye 2 had extremely
low dye fixation efficiency on cellulosic substrate. After wash off
procedure, approximately 90% of dye 2 was washed away. Thus the
application of dye 2 on cotton via inkjet printing and the follow-up tests
did not carry on.
2.1.3 Synthesis of Dye 3
In this process, commercial reactive dye MX-2G blue was modified by
chemical reactions and converted to phosphonic acid dye 3.
Experimental Materials:
H-acid, Crystalline phosphorous acid, Hydrochloric acid, distilled water.
N.B. Chemicals used in this research are laboratory-grade standard, and
supplied either by Sigma Aldrich or by BASF.
A highly reactive dye (dichlorotriazine) was selected and used in the
study. It was applied and manufactured by Kemtex, UK, under the
commercial name Procion blue MX-2G.
Equipment and instrumentation:
Fume Hood, Balance (electronic), Beakers, Pipettes, Spatula, Stirring
rods, , Weight boat, Paper towels, dropping funnel, thermometer with
quick-fit adapter, a 3-neck 250ml round-bottom flask, oil bath, hotplate,
laboratory jack, overhead-stirrer, iron stand, desiccator & vacuum pump,
100ml single neck round bottom flask, magnetic stirrer, reflux condenser,
Rotary Evaporation.
61
5.0g of H-acid (4-Amino-5-hydroxy-2, 7-naphthalenedisulfonic) was
dispersed in 50 ml f water in a 100 ml 3-necked round-bottom flask.
Added 1.0g of phosphorous acid.
Slowly dropped in 1.8g of hydrochloric acid.
Placed the flask in an oil bath, fitted with condenser, thermometer and
dropping funnel, then heated to reflux.
Placed 1.0g of formaldehyde solution in the dropping funnel.
Slowly dropped the formaldehyde solution to the refluxing H-acid
solution.
Tested for the presence of unreacted H-acid with Ehrlich reagent at
intervals. N.B. Ehrlich reagent will turn orange in the presence of free
aromatic amine.
Left to reflux for an additional hour.
Decanted the solution into a rotavap flask. In this step, the refluxing
solution turned into thick, black goop and no longer able to decant into a
rotavap. A repeat experiment was carried out again in the same condition,
and the same unknown substance (thick & black goop) was arising in the
round-bottom flask.
Since this, the synthesis method was not able to modify the commercial
dye (MX-2G Blue) in practice.
2.2 Application of modified dye to cotton
2.2.1 Pad-batch method
62
In section 2.1, as the synthesised dye 2 & 3 was not suitable for cellulose
dyeing and printing, the synthesised dye 1 was used in the follow-up
process. In later sections, the modified dye and the phosphonic containing
dye only reference to the synthesised dye 1(Fig 2.5).
To investigate the effect of cyanamide and dicyandiamide concentration
on the padding procedure, the pad liquors were prepared with varying
concentrations of catalyst.
Experimental Materials:
The fabric used in this study was scoured and bleached plain weave 100%
cotton. The cotton fabric was cut in size 20cm * 20cm.
Dyestuffs:
Modified dye synthesised in section 2.1.1.
Auxiliaries:
The following auxiliaries and chemicals were used either for pad-bake
method or for the inkjet printing on cotton (Gillingham et al, 2007).
Ammonium dihydrogen phosphonate, supplied as a dry crystalline
powder.
Cyanamide was supplied as a 50% aqueous solution.
Dicyandiamide was supplied as a dry crystalline powder. According to
specification of dicyandiamide from Sigma-Aldrich, the solubility can be
50 g/L. Actually the solubility is lower than the specification at room
temperature.
63
N.B. Chemicals used in this research are laboratory-grade standard, and
supplied either by Sigma Aldrich or by BASF.
Equipment and instrumentation:
Fume Hood, Balance (electronic), Beakers, Pipettes, Spatula, Stirring
rods, Weight boat, Paper towels, Matthis Laboratory pad mangle, Mathis
forceddraft oven, volume flask, polythene, Anion detergent, hot plate.
2.2.1.1 Pad liquor preparation
Pad liquors were prepared containing the phosphonic acid containing
dye (10 g dm-3
), ammonium dihydrogen phosphate (10 g dm-3
) and
catalyst (0, 30, 60, 90, 120 and 150 g dm-3
).
Stock solutions of dye and ammonium dihydrogen phosphate were made
up by dissolving 3.125g dye and ammonium dihydrogen phosphonate
powder in distilled water.
Cyanamide stock solution was used directly from 50% aqueous solution.
In actual practice 50% concentration for dicyandiamide solution cannot
achieved in room temperature. Dicyandiamide is unlikely to completely
dissolve in water at concentration in excess of 40 g/L. However its
solubility increases with increase in the water temperature quickly.
Pre-heated distilled water to 35ºC , and then the warm water was used to
dissolve dicyandiamide powder to obtain 50 g/L stock solution.
The concentration of catalyst was varied (0, 30, 60, 90, 120 and 150 g
dm-3
of cyanamide and dicyandiamide) to give a series of pad liquors.
64
Each pad liquor (25ml) containing 4 ml dye stock solution, 4 ml
ammonium dihydrogen phosphonate stock solution, X ml catalyst
(cyanamide or dicyandiamide), required amount of distilled water to fill
up to 25 ml. Symbol X on behalf of the cyanamide or dicyandiamide
volume used in different catalyst concentration. Table below show the X
variation in each pad liquor.
Cyanamide (X) Dye Ammonium dihydrogen phosphonate
Pad liquor 0 0ml 4ml 4ml
Pad liquor 1 1.5ml 4ml 4ml
Pad liquor 2 3ml 4ml 4ml
Pad liquor 3 4.5ml 4ml 4ml
Pad liquor 4 6ml 4ml 4ml
Pad liquor 5 7.5ml 4ml 4ml
Table 2.1Pad liquor pepartion (Cyanamide)
Dicyandiamide (X) Dye Ammonium dihydrogen phosphonate
Pad liquor 0 0ml 4ml 4ml
Pad liquor 1" 1.5ml 4ml 4ml
Pad liquor 2" 3ml 4ml 4ml
Pad liquor 3" 4.5ml 4ml 4ml
Pad liquor 4" 6ml 4ml 4ml
Pad liquor 5" 7.5ml 4ml 4ml
Table 2.2 Pad liquor pepartion (Dicyandiamide)
65
2.2.2.2 Pad/Pad (batch)-bake process
Prepared 11 clean volume flasks (25ml), labeled them from Pad liquor 0
to Pad liquor 5". Added corresponding regents into the volume flask as
illustrated in table 2.1 and Table 2.2.
After adding the reagents, each pad liquor adjusted pH to 5-5.5 with small
amounts of aqueous ammonia. Then added distilled water to fill up to
25ml. Shaked well prior to applying pad liquor to cotton fabric.
The padding process was carried out on a Matthis Laboratory pad mangle,
with nip-pressure set to obtain approximately 74% wet pick-up.
Deeply cleaned the padding mangle before applying pad liquor to cotton.
Turned on the pad mangle and set air pressure at 4 bars with rotational
velocity set at 1.6 r/min.
Decanted one pad liquor into padding trough, fed one piece of prepared
cotton fabric in to squeeze roll. The uniform expression of the pad liquor
was achieved by passing the cotton fabric through the arranged rolls, as
cotton emerged from the trough.
The freshly padded fabric was cut into two; one half of each piece was
wrapped in polythene immediately to avoid any air exposure and then
batched at room temperature for 24 hours. The other half just dried on
frames.
The following day, both fabrics were mounted on pin frames and
pre-dried at 100ºC in a Mathis forceddraft oven for 2 min.
66
Then samples were baked at 185ºC for 90 secs.
N.B. According to the reference experiment (Estelle L Gillingham &
David M Lewis, 2007), the cotton fabrics was baked at 200ºC for 90 secs.
In this research, the sample fabrics were firstly baked at 200ºC for 90 secs.
But the high baking temperatures caused serious fabric yellowing. This
will influence the hue of shade. In order to avoid this happening, lower
the baking temperature is necessary. Therefore, several attempts were
carried out. The sample fabrics were then baked at 195ºC, 190ºC, 185ºC
for 90 seconds respectively. The end results indicate that baked a 185ºC
for 90 seconds would not affect the hue of shade and would not yellowing
the cotton fabric. At that point, baked at 185ºC for 90 seconds is the
optimum conition.
The washing off procedure was then carried at boiling aqueous solution
(nonionic detergent: water, 1:50) for 15 min. Later cold rinse was
repeated until the rinse water was colourless. Keep the wash up liquors
for later measurement.
Air dried fabrics at room temperature for later use
2.2.2 Inkjet printing via modified dye
As described in section 1.1.2.2, unlike the conventional reactive printing
on cotton, in inkjet printing process cotton needs to be pre-treated with
fixation-enhancing chemicals prior to jet eject ink droplet. In
pre-treatment procedure cotton fabrics were padded with pre-treatment
67
paste. In this case, the pre-treatment paste was prepared with ammonium
dihydrogen phosphonate and varying concentrations of catalyst
(cyanamide and dicyandiamide).
Experimental Materials:
The fabric used in this study was scoured and bleached plain weave 100%
cotton. The cotton fabric was cut in size 20cm * 20cm.
Dyestuffs:
Modified dye synthesised in section 2.1.1.
Auxiliaries:
The following auxiliaries and chemicals were used either for pad-bake
method or for the inkjet printing on cotton (Gillingham et al, 2007).
Ammonium dihydrogen phosphonate, supplied as a dry crystalline
powder.
Cyanamide was supplied as a 50% aqueous solution.
Dicyandiamide was supplied as a dry crystalline powder.
Equipment and instrumentation:
Fume Hood, Balance (electronic), Beakers, Pipettes, Spatula, Stirring
rods, Weight boat, Paper towels, Matthis Laboratory pad mangle, Mathis
forceddraft oven, volume flask, polythene, Anion detergent, hot plate,
Wolke m600 ink-jet printer, HP ink cartridge, syringe equipped with a
0.45 μm cellulose acetate filter.
2.2.2.1 Preparation of pre-treatment paste
68
The aqueous pre-treatment paste (25ml) was prepared containing the
ammonium dihydrogen phosphate (10 g dm-3
) and catalyst (0, 30, 60, 90,
120 and 150 g dm-3
). The stock solutions were prepared in section 2.2.1.
Each paste containing 4 ml ammonium dihydrogen phosphonate stock
solution. Y ml catalyst (cyanamide or dicyandiamide), required amount
of distilled water to fill up to 25 ml. Symbol Y on behalf of the
cyanamide or dicyandiamide volume used in different catalyst
concentration. Table below show the Y variation in each pad liquor.
Cyanamide
(Y)
Ammonium dihydrogen phosphonate
Pre-treatment paste 0 0ml 4ml
Pre-treatment paste 1 1.5ml 4ml
Pre-treatment paste 2 3ml 4ml
Pre-treatment paste 3 4.5ml 4ml
Pre-treatment paste 4 6ml 4ml
Pre-treatment paste 5 7.5ml 4ml
Table 2.3 Pre-treatent paste pepartion (Cyanamide)
Dicyandiamide
(Y)
Ammonium dihydrogen phosphonate
Pre-treatment paste 0 0ml 4ml
Pre-treatment paste 1" 1.5ml 4ml
Pre-treatment paste 2" 3ml 4ml
Pre-treatment paste 3" 4.5ml 4ml
Pre-treatment paste 4" 6ml 4ml
Pre-treatment paste 5" 7.5ml 4ml
69
Table 2.4 Pre-treatent paste pepartion (Dicyandiamide)
2.2.2.2 Pre-treatment and Inkjet printing process
Prepared 11 clean volume flasks (25ml), labeled them from Pre-treatment
paste 0 to Pre-treatment paste 5". Added corresponding regents into the
volume flask as illustrated in Table 2.3 and Table 2.4.
After adding the reagents, each pad liquor adjusted pH to 5-5.5 with small
amounts of aqueous ammonia. Then the paste was made up to a volume
of 25ml with distilled water. Subsequently mixed thoroughly prior to
applying pre-treatment paste to cotton fabric.
2.2.2.2.1 Pre-treat sample fabrics
The padding process was carried out on a Matthis Laboratory pad mangle,
with nip-pressure set to obtain approximately 74% wet pick-up. And a
constant padding speed of 1.6 r/min.
Decanted one pre-treatment paste into padding trough, fed one piece of
prepared cotton fabric in to squeeze roll. The uniform expression of the
paste was achieved by passing the cotton fabric through the arranged rolls,
as cotton emerged from the trough.
Air dried the padded fabrics at room temperature and then conditioned
before inkjet printing.
2.2.2.2.2 Inkjet printing process
The ink-jet printing was carried out on a Wolke m600 ink-jet printer.
70
Ink preparation
Reactive dye synthesised in section 2.1 was used in this case. The
concentration of dye solution was 10g dm-3
. Dissolved 2.5g dye in 50ml
distilled water and stirred evenly. The prepared ink was filtered through a
syringe equipped with a 0.45 μm cellulose acetate filter of 25 mm
diameter to prevent clogging the jet nozzle before filling into the
cartridge. Before filling dye solution, the ink cartridge was deeply
cleaned, filled with distilled water. After that put the cartridge back to
printer and printed on a blank cotton fabric until no more colour shade
come out of the ink cartridge. In this way, the jet nozzle was flushed
thoroughly so that the ink used in the later would not be affected by the
previous content. After that was complete, emptied out the water inside of
the cartridge and kept upside down for a day to flush off remaining water.
Then filled the filtered dye solution into ink cartridge slowly, sealed filler
hole well.
Mounted ink cartridge onto the printer. A piece of cotton substrate was
clipped together with printer bed.
Turned on printer and selected Label→PR→Load on the screen of
printer.
When the indicator light turns green, which means it is ready to print.
Grabbed the holder of printer and moved toward the left hand direction
71
until the printing plate passed the sensor, which was located on the printer
bed.
After that, returned the printing bed to the original position. One printing
pass has been done.
Once a certain area had been printed, shifted the sample fabric to an
unprinted area.
Followed the process described above to print the rest pre-treated fabrics.
Printed fabrics were mounted on pin frames and pre-dried at 100ºC in a
Mathis forceddraft oven for 2 min.
Then samples were baked at 185ºC for 90 secs.
The washing off procedure was then carried at boiling aqueous solution
(nonionic detergent: water, 1:50) for 15 min. Later cold rinse was
repeated until the rinse water was colourless.
Dried in the air.
For comparing and analyzing the influence of catalyst on cotton fabric, an
unpretreated reference cellulose fabric was printed via inkjet printing as
described above. After printing, dried in the air and carried out the wash
off process.
2.3 Inkjet printing via Desktop inkjet printer
In order to assess effects of dye application on strength retention of cotton
substrate, the dye modified in section 2.1.1 was applied on cotton fabric
through desktop inkjet printer. Then the printed samples were tested on
72
Instron Tensile Strength instrument. Compared the results with blank
cotton fabric, the influence of dye applied would be obtained.
Experimental Materials:
The fabric used in this study was scoured and bleached plain weave 100%
cotton. In order to fit the fabrics in the printer, the size of cotton samples
is same as A4 paper. Cut 5 pieces of A4 size cotton samples from the
cotton roll.
Dyestuffs:
Modified dye synthesised in section 2.1.1.
Auxiliaries:
The following auxiliaries and chemicals were used either for pad-bake
method or for the inkjet printing on cotton (Gillingham et al, 2007).
Ammonium dihydrogen phosphonate, supplied as a dry crystalline
powder.
Cyanamide was supplied as a 50% aqueous solution.
Dicyandiamide was supplied as a dry crystalline powder.
Equipment and instrumentation:
Fume Hood, Balance (electronic), Beakers, Pipettes, Spatula, Stirring
rods, Weight boat, Paper towels, Matthis Laboratory pad mangle, Mathis
forceddraft oven, volume flask, polythene, Anion detergent, hot plate, HP
Deskjet 840c printer, 3M adhesive, HP ink cartridge, syringe equipped
with a 0.45 μm cellulose acetate filter.
73
2.3.1 Pre-treatment of cotton fabrics
The aqueous pre-treatment paste (25ml) was prepared containing the
ammonium dihydrogen phosphate (10 g dm-3) and catalyst (150 g dm-3).
The stock solutions were prepared in section 2.2.1.
Each paste containing 4 ml ammonium dihydrogen phosphonate stock
solution. 7.5 ml catalyst (cyanamide or dicyandiamide), required amount
of distilled water to fill up to 25 ml. Table below show the component in
each pad liquor.
Cyanamide Dicyandiamide Ammonium dihydrogen
phosphonate
Pre-treatment paste
Cyanamide
7.5ml 0ml 4ml
Pre-treatment paste
Dicyandiamide
0ml 7.5ml 4ml
Table 2.5 Pad liquor component
Prepared 2 clean volume flasks (25ml), labeled them from Pre-treatment
paste Cyanamide and Pre-treatment paste Dicyandiamide. Added
corresponding regents into the volume flask as illustrated in Table 2.5.
After adding the reagents, each pad liquor adjusted pH to 5-5.5 with small
amounts of aqueous ammonia. Then the paste was made up to a volume
of 25ml with distilled water. Subsequently mixed thoroughly prior to
applying pre-treatment paste to cotton fabric. The padding process was
carried out on a Matthis Laboratory pad mangle, with nip-pressure set to
obtain approximately 74% wet pick-up. And a constant padding speed of
1.6 r/min. As described in section 2.3.2.
74
Air dried the padded fabrics at room temperature and then conditioned
before inkjet printing.
For the purpose of study how the catalyst would affect fabric tear strength,
an unpre-treated cotton sample would be printed via desktop inkjet printer
as a control.
2.3.2 Desktop inkjet printing process
Before printing on fabrics, an important ancillary step is necessary.
Because the cotton fabrics cut from the beam were too soft to feed into
desktop printer, it is necessary to stick fabric to a firm paperboard. The
following step in necessary to achieve this aim.
Sprayed adhesive onto a piece of A4 size firm paperboard uniformly.
Sticked one piece of cotton fabric to the paperboard with caution, make
sure the sample fabric dose not wrinkle up when it is stretched during this
process.
Applied even pressure over the entire sample fabric through hands,
ensure the firm binding of fabric and paperboard.
Dried in the air.
In this case, 3 bonded sample fabrics were prepared: Cyanamide and
Dicyandiamide pretreated cotton fabrics and one unpre-treated sample
fabric.
2.3.2.1 Desktop inkjet printing:
75
Used the same ink cartridge in section 2.3, mounted it onto the desktop
inkjet printer. Connected printed and computer.
Opened Microsoft Word, set the background of writing board as black.
Fed one of the three bonded print substrate into paper feed channel, make
sure the cotton fabric side would be printed later.
Clicked File-print, on the print setting board, ticked print background,
then clicked print.
Air dried the printed fabric.
Printed the rest two samples as mentioned above.
Peeled the cotton fabric from the paperboard carefully.
Placed these printed fabrics on the table, allowed them to dry completely.
2.3.2.2 Dye fixation (bake) process
In this step, a piece of white (unprinted) sample fabric was baked as the
others in order to achieve comparison data afterwards.
Printed fabrics were mounted on pin frames and pre-dried at 100ºC in a
Mathis forceddraft oven for 2 min.
Then samples were baked at 185ºC for 90 secs.
The washing off procedure was then carried at boiling aqueous solution
(nonionic detergent: water, 1:50) for 15 min. Later cold rinse was
repeated until the rinse water was colourless.
Dried in the air for subsequent requests.
76
3 Evaluate modified dye performance
3.1 Colour strength measurement for inkjet printed sample
fabrics via spectrophotometer
CIE L*a*b* colour space supports the accepted theory of colour
perception based on three separate colour receptors, RGB (Red, Green,
and Blue), in the eye. When reflected light reaches these receptors, they
are excited. This results in three sets of signals being sent to the brain:
light or dark, red or green, and yellow or blue (Hunt, 1987). As shown
below.
Figure3. 1 CIE L*a*b* (http://dba.med.sc.edu/price/irf/Adobe_tg/models/cielab.html)
L* is a measure of the lightness of an object and ranges from 0 (black) to
100 (white).
a* is a measure of redness (positive) or greenness (negative).
b* is a measure of yellowness (positive) or blueness (negative).
A spectrophotometer compares the amount of light that is shined onto an
object with the amount of light that is reflected back from that object. It
analyzes light energy reflected or transmitted by a sample, wavelength by
77
wavelength.
Figure3.2 Spectrophotometer Datacolor 650
From the spectral energy distribution of one or more illuminants (e.g. A,
C, D65), tristimulus responses of standard observes (2°or 10°) and the
spectral graph of the sample, spectrophotometer calculates the tristimulus
value for any illuminant and one observer. It is simple and rapid to use.
In this case, the Datacolor 650 spectrophotometer was used to measure
the L* (lightness) of inkjet printed fabrics in section 2.3. The software
used in this measurement is datacolor TOOLS, Version 2.0.1.
3.1.1 Measure samples
Opened software on computer, applied the following options for the
settings:
Specular:Exclude
Aperture: Small
78
UV-Filer: 100% UV (Filter off).
Calibrated the spectrophotometer then.
After calibration, folded one sample twice until no light can go through
sample.
N.B. one sample consists of two areas: printed and unprinted area, make
sure fold the wanted area outside. In this operation, always measure the
unprinted area firstly.
Attached folded sample to presentation port, clicked confirm label on the
control interface to measure L*.
Shifted sample to another location and measured again.
Measured four different locaions, and the processor would give an
average value for each measured area.
Afterwards, measured the printed area by the same steps.
After finishing all the measurement, printed the value form. N.B. form
titled with 0.1 stands for unprinted area, 0.2 stands for printed area.
N.B. the L* is measured under CIE Standard Illuminant D65. The
measurement data is attached in appendix.
3.2 Tensile Test
Tensile test tests a material's strength. It is a mechanical test where a
pulling force is applied to a material from both sides, until the sample
breaks, which is commonly used to determine the maximum force that a
material can withstand. Thus curve of tensile profile showing how
79
material will react to pulling force being applied can be obtained. By
measuring changes, a variety of information including yield point (the
amount of tension that causes the sample to break), tensile strength and
ultimate strength (the maximum tensile force that the sample can stand)
of the material can be determined, which is helpful in deciding whether it
is a suitable choice for the certain application.
Figure3.3 Instron Force Transducer
The result of this test is a curve of force (amount of weight) versus
displacement (amount it stretched).
The basic theory of a tensile test is to place a sample of a material
between two grips, which clamp the sample material. Then begin to apply
80
pulling force to the material gripped at one grip as the other grip is fixed.
Keep increasing the force while at the same time measuring the change in
length of the sample.
Tensile test is very important in numerous industries, especially in textile
industry. For example, during the planning stage of a garment, for stable
construction and durable purpose, select appropriate material which will
able to withstand certain stresses and abrasion without breaking.
3.2.1 Tensile Procedure
In order to investigate the influence of temperature on cotton fabric
strength, an unpre-treated and unbaked cotton fabric was tested as a
reference. As described in section 2.4, 5 pieces of sample fabrics were
carried out through tensile test.
Pretreated Printed baked Wash off
sample 1 Cyanamide √ √ √
sample 2 Dicyandiamide √ √ √
sample 3 / √ √ √
sample 4 / √ √
sample 5 / √
Table 3.1Samples preparation.
In principle, there were two sets of test specimen (quantity 2 per set): one
in the warp direction and the other in the weft direction of the cotton
fabric.
81
Cut 4 specimens 50mm wide and 200mm long. Removed an equal
number of yarns from each side in order to obtain a 50mm width. N.B:
take utmost care in cutting specimen to prevent tears along the edges of
the fabric.
Placed the one piece of specimens in the grips of the testing machine,
make sure the specimen aligned with the direction of pull perfectly.
The test machine is then controlled by computer software. The software
steadily increased the force exerted on the specimen, along with
displacement, until the specimen failed.
The testing software automatically calculated results and statistics, and
finally produced a test report including the recorded force-elongation
curve.
Removed the failed specimen from the machine and fitted the new
specimen. Repeated the steps as above.
In the end, collected all the reports of specimen for later analysis.
3.3 Ultraviolet-Visible spectrophotometry
UV-visible spectrophotometry is one of the most important techniques in
chemical analysis. By measuring the amount of ultraviolet or visible light
and the wavelength that a compound absorbs, the molecular structure and
the concentration can be determined (Behera et al. 2012). See Fig 3.4.
82
Figure3. 4 UV-Spectrophotometer (UV-VIS Spectroscopy - Chemical Analysis, 2009)
The fundamental law used in spectrophotometry is the Beer-Lambert law,
shown as below:
Figure3. 5 Beer-Lambert law (UV-VIS Spectroscopy - Chemical Analysis, 2009)
In this search, the solutions in section 2.2 were measured their absorbance
at suitable wavelength. Generally the wavelength selected is at the
maximum absorption.
3.3.1 Sample measurement
A Camspec M550 Spectrophotometer with matched cuvettes was used in
this research.
In section 2.2, the wash off solutions were kept and measured in this
stage. Three samples were collected from each wash off solution, and
measured separately. Then the average value was calculated and recorded.
N.B. only closeness value would be accepted and calculated.
83
Turned on the Spectrophotometer and allowed at least 15 minutes to warn
up.
After the warm up was completed, connected the Spectrophotometer and
the software installed in the computer. Then the Spectrophotometer was
controlled by the software.
On the file menu, clicked new and selected Wavelength Scan
Measurement and clicked OK
Then clicked D2/W Switch Point, set the lamp switching wavelength
position within the range 339 nm to 370 nm.
Clicked icon A from the menu to select absorbance mode.
Afterwards, entered wavelength scan range in the FROM box. In this case,
the range from 300nm-700nm. Clicked ok return to the menu. Now the
operation conditions for wavelength scanning were set up and ready to
collect a spectrum.
Closed the cover of sample compartment. On the UV-Photometer menu,
clicked Background on the tool bar. The UV-Photometer would run
background correction automatically until the status bar show Ready.
Transferred the wash off solutions to the corresponding cuvettes, and
labeled these cuvettes.
Placed sample cuvettes which contain blank solutions in both the
reference and sample cuvette holders.
On the UV-Photometer menu, clicked Autozero on the tool bar to zero
84
the instrument.
Placed a sample cuvette which contains wash off solution in the sample
cuvette holder. Closed the cover of the compartment.
Clicked the Operation icon on the tool bar, the instrument would start
scanning automatically.
As the scanning going on, the real time spectrum would be displayed on
the screen.
Saved the spectrum when the scanning is over.
Measured the rest sample cuvettes as above steps.
The absorbance at the wavelength of maximum absorption (λmax) was
measured and recorded.
3.3.2 Standard solution make up
In order to obtain the concentration of the wash off solution in section 2.2,
more dye solutions are needed to be measured to create a calibration plot.
A sequence of gradual step-down trend dye solutions (standard solutions)
were made up. These solutions were all diluted from the dye stock
solution (10 g/L).
The concentrations of these standard solutions are accurately known, and
they were all well labeled.
Standard solutions were measured as described above.
The absorbance at the wavelength of maximum absorption (λmax) was
obtained and recorded.
85
3.4 Fourier Transform Infrared Spectroscopy
An FTIR (Fourier Transform Infrared Spectroscopy) technology is used
to identify the possible functional groups in chemical compounds. By
exciting the molecular rotation and vibration via the absorption of
infrared radiation, the interaction of molecules can be identified and
measured (Kan, et al. 2000). As known that when chemical compound
interacts with infrared radiation, only certain frequencies energy can be
absorbed, meanwhile the others are either reflected or transmitted. The
frequencies are depending on the functional groups within the chemical
compound, and each of groups has the unique frequency. Thus the
functional groups are localized by their unique absorption frequencies
(Manfred, et al. 1997). By means of this technology, the chemical
composition of substance can be determined.
Figure3.6 Regions of the Infrared Spectrum for analysis (Organic Structural Spectroscopy. 1998).
In this research, FTIR was used to determine the likely functional groups
86
present in commercially reactive dye molecules and modified reactive
dye molecules. According to the previous studying (Manfred, et al. 1997),
there are two major regions in FTIR spectrum. Absorption bands located
in above 1500cm-1
region can be vest in individual functional groups.
Meanwhile the region below 1500cm-1
contains many bands and
characterizes the molecule as a whole. It called as the fingerprint region.
Absorption bands arise from functional groups within the fingerprint
region can be used to identify groups, but this determination should only
consider as an aid to identification, not as a conclusive proof.
In order to interpret the FTIR spectra of the two samples, a reference
table of FTIR functional group is necessary to indicate the possible
groups within the dyes.
A Camspec M550 FT-IR spectrometer was used to obtain the IR spectrum
of the dye sample.
3.4.1 FT-IR measuring procedure
Before measuring the sample dye, the test bench was cleaned deeply so as
to eliminating the interference.
FT-IR spectrometer and control computer were well connected.
Opened the Ominc software and chose the option: smart orbit.
Set the testing content as Absorbance.
After that, scanned the background of FT-IR. This step was designed to
eliminating the effect of background absorption.
87
Then placed one of the sample dye on the test bench, make sure the dye
powder covered the light hole of test bench.
Scanned the sample twice.
Removed the sample above, cleaned test bench and placed the other
sample dye. Scanned the sample twice as well.
The Ominc software generated the sample spectra, at the same time the
major peaks were labelled and numbered.
3.5 Thin layer chromatography
Thin layer chromatography (TLC) technique is used to separate mixtures
into their individual components. It is used extensively in both the
industry and research laboratories because it can be controlled very
precisely and uses very small amount of substance.
In TLC, there are two phases in separating the compound—stationary
phase and mobile phase. Solvent can be used as eluent in TLC.
According to the chromatography theory, different compounds have
different solubility and adsorption in the two phases. In chromatography,
a mobile phase (liquid or gas) flows through a stationary phase (often a
solid) and carries the components of a mixture with it. Duo the different
adsorption rate of different compounds, the migration speed of each
compound will be different, and therefore separation of the mixture can
be obtained. Different functional groups in mobile phase interact with
stationary phase determine the adsorption degree of compounds.
88
Figure3.7 The separation of a mixture of molecules A&B
(http://www.chemguide.co.uk/analysis/chromatography/thinlayer.html)
In TLC, the stationary phase (TLC plate) consists of a thin layer of silica
gel (or alumina) coated over a piece of solid inert medium (usually
aluminium or plastic), and often contains a substance that fluoresces
under UV irradiation to facilitate the detection of colourless substances.
In this experiment, the TLC plate consists of a thin plastic sheet covered
with a thin layer of silica gel, the structure is shown below.
Figure3.8 A portion of silica gel (http://www.chemguide.co.uk/analysis/chromatography/thinlayer.html)
Silica gel consists of a three-dimensional network of thousands of
alternating silicon and oxygen bonds, with O-H groups on the outside
surface. Hence the silica gel consists of polar functional group. Highly
polar molecules will interact strongly with the polar Si-O bonds in silica
89
gel and thus the high polar molecules will tend to adsorb onto the TLC
plate. On the other hand, less polar molecules will tend to travel more
rapid than the high polar one.
In this research, TLC is used to determine if two compounds (commercial
dye and modified dye) are identical. A spot of the compound being
investigated is placed on a chromatography plate, and a spot of a
manufactured sample is placed next to it. The plate is then allowed to
stand in a suitable solvent, which travels up the plate, seen as Fig 3.9.
Figure3.9 TLC theory
If the compound to be identified leaves exactly the same pattern on the
chromatography plate as the known compound, it can be conclude that
they are the same. Otherwise, they have different compositions.
3.5.1 Producing the chromatogram
A specially designed chamber with a lid,
In this research, solvent were prepared. The compositions solvent is listed
below:
90
Ethyl acetate 5 ml
Butanol 10 ml
Propanol-1 15 ml
Distilled water 20 ml
Table 3.2 Solvent component
As the polar solvent may change the adsorption of polar molecules, the
more polar the solvent, the faster the compound can move over the
surface. This will lead to all the mixture travel almost at the same speed.
But, at the same time the separation between non-polar compound and
polar compound may not quite distinct. As a result, a mixed solvent
which is prepared by mixing high polarity and low polarity solvents
would be better to separate compound. In this way the polarity of the
solvent can be controlled and any polarity can be created.
Before producing the chromatogram, small and same amount of the
commercial dye MX-2G reactive dye and modified dye were dissolved in
Solvent. Added a little bit more of solvent if the dye powder did not fully
dissolved.
A pencil line is drawn near the bottom of the plate. Under the line,
marked lightly the name (point 1 and point 2) of the sample solutions
which would spot on the plate. Left enough space between the samples so
that they do not run together.
Obtained a microcapillary, dipped the microcap into one of the prepared
dye solution and then gently touched the end of it onto the proper location
on the TLC plate. A small drop of the MX-2G dye solution was placed on
91
it. Repeated this step and a small drop of modified dye solution were
placed next to point 1, named as point 2. As shown in Fig 3.10.
Figure3.10 TLC Plate ready to be spotted (Thin Layer Chromatography lab. proc. UoM)
Poured solvent into the chambers to a depth of just less than 0.5 cm
respectively. To aid in the saturation of the TLC chamber with solvent
vapors, a piece of filter paper was lined part of the inside of the beaker.
Placed the prepared TLC plate in the chamber, covered the beaker with
the lid, and left it undisturbed on the bench top. The solvent would rise up
the TLC plate by capillary action. Make sure the solvent does not cover
the spot. As seen below.
Figure3.11 TLC plate in solvent (http://www.chemguide.co.uk/analysis/chromatography/thinlayer.html)
As the solvent slowly travels up the plate, the different components of the
92
dye mixture travel at different rates and the mixture is separated into
different coloured spots.
The solvent is allowed to rise until it almost reaches the top of the plate.
Marked the position of the solvent front with a pencil before it evaporates.
As seen in Fig 3.12
Figure3.12 Components travelled different distance
(http://www.chemguide.co.uk/analysis/chromatography/thinlayer.html)
3.5.2 Rf Values
In addition to qualitative results, Rf Values is used to measure the
movement of the components along the plate. The Rf Values (retention
factor) is defined as the distance travelled by the analyte divided by the
distance travelled by the solvent. As an example, Fig 3.13 explains how
to calculate the Rf Values.
Figure3.13 Calculation of Rf value (Thin Layer Chromatography lab. proc. UoM)
Comparing the Rf Values with the Rf Values of known compounds might
93
enable a tentative identification to be indicated. If a solvent has a high
polarity, all components in the compound will travel along with the
solvent and separation may not be obtained. If the solvent has low
polarity the components will not travel enough so that separation may not
occur as well.
Since some components may have similar polarities, many of them can
have the same Rf Values. Additional determination must be carried out
before the final conclusion can be made.
In this research, TLC was used on a microscale to monitor a reaction and
determine if the product was successfully synthesised.
94
4 Results and Discussion
4.1 Dye analysis
The success of the synthetic route to the phosphonic acid containing dye
was confirmed by TLC and FT-IR techniques.
4.1.1 Thin layer chromatography
Thin layer chromatography (TLC) test of MX-2G reactive dye and
synthesised phosphonic acid containing dye indicates these two dyes are
different. As seen in Fig 42, the side-on view of the development of a
TLC plate. As the solvent travels along the plate, equilibrium between the
movement solvent and the TLC plate for the dye is established. Simply
the silica on the TLC plate tries to bind the dye molecules and the moving
solvent tries to dissolve the dye, carrying the dye molecules along as the
solvent travels up wards. To put it simply, the process of TLC relies on
the question: would the dye prefer to be stuck on the plate or would it
prefer to travel along with the solvent?
Since the polarity of the TLC plate is high and is constant at high level,
the balance of interactions mainly depends on the polarity of the solvent
and the polarity of the compounds applied for separation. If a sample
solute consists of two components, one more polar than the other, the
more polar will tend to stick more tightly to the plate and the less polar
will tend to move along more freely with the solvent. As shown in Fig
95
4.1.
Figure 4. 1 Example of the analysis of a two component mixture
(http://www.nature.com/nprot/journal/v9/n8/fig_tab/nprot.2014.128_F5.html)
The Rf Value can provide corroborative evidence to identify compounds.
In this case, a standard sample (original dye) was spotted and ran on a
TLC plate side by side with the compound in question under identical
chromatography condition.
Figure 4. 2 TLC test for modified dye (left) and original dye
96
In Fig 4.2, the left spot represents the movement of modified dye, the
right side spots stands for original dye (MX-2G). As can be seen from Fig
4.2, two spots (Lower spot: A, higher spot B) are located on the right side.
This could attribute to the hydrolysis of original dye (MX-2G Blue). As
mentioned in section 2.1.1.2, the purity of commercial dye MX-2G Blue
was not 100%. Part of the original dye was possibly hydrolysed during
storage. The polarity of the MX-2G Blue and hydrolysed MX-2G Blue
were different, and thus they can travel different distance on silicon
surface. In this way two spot can be observed from the original dye
pathway (right side).
As seen in Fig 4.2, the modified dye (left side) travel distance was
different from the original dye (spot A and spot B).
The travel distance and Rf Values are measured as below.
Distance of solvent travelled =6.9 cm
Distance travelled by modified dye: 1.29 cm
Distance travelled by commercial dye A: 1.70 cm
Distance travelled by commercial dye B: 2.26 cm
Rf Value of modified dye = 0.187
Rf Value of commercial dye A= 0.246
Rf Value of commercial dye B= 0.327
As the two substances have different Rf Values, they are definitely
different compounds.
97
4.1.2 FT-IR
The spectras of commercial dye (MX-2G) and synthesised dye are shown
in Fig 4.3 and 4.4. .
Figure 4. 3 Spectrum of MX-2G Blue
Figure 4. 4 Spectrum of synthesised phosphonic acid containing dye
The FT-IR spectrum for the MX-2G dye shows the absorbance of C-Cl
band at 797 cm-1
. Comparing with the starting dye, it can be seen there is
no C-Cl absorbance at 797 cm-1
of spectrum for the synthesised
98
phosphonic acid containing dye. This shows that the dye has reacted,
either been converted to the new phosphonic acid containing dye or
hydrolysed during the synthesis pathways.
The spectrum of the synthesised phosphonic acid containing dye shows a
new, high intensity absorbance band at 1100 cm-1
, which stands for P=O
stretching (aliphatic). A medium intensity absorbance at 910 cm-1
can be
attributed to P-O stretching (P-OH bonds). The identification values are
referenced from Characteristic Infrared Absorption Frequencies
(Silverstein et al. 1998; Solomons et al. 2001). This new peak illustrates
at least proportional dye was converted.
4.2 Application of synthesised phosphonic acid containing
dye to cotton
4.2.1 Effect of Catalyst type and Concentration on dye
fixation via Pad-bake method
As described in section 2.2, in order to investigate the effect of catalyst
type and catalyst concentration on dye fixation, the pad liquors were
prepared containing cyanamide and dicyandiamide at varying
concentrations (0, 30, 60, 90, 120 and 150 g dm-3
). The dye performance
can be assessed by measuring the Absorbance of coloured solutions
before and after wash off through UV-visible spectrophotometry.
As mentioned in section 3.3, a number of accurately known concentration
solutions of the dye were made up (standard solutions). The wash off
99
solutions is unknown and the concentration of dye in the wash off
solutions can be determined by measuring their absorbance. According to
Beer’s law, the amount of radiation absorbed, i.e. absorbance, directly
proportional to concentration (O. Thomas & C. Burgess, 2007). Hence, as
the concentration of a compound dissolved in solvent increases, the
absorbance of the solution should also increase proportionally. Taking
advantage of this relationship, these standard solutions should bracket the
concentration being identified, some of them may be less concentrated
and some may be more concentrated.
For each standard solution, the absorbance at the wavelength of
maximum absorption (λmax) was measured (λmax=611 nm-1
). Then a
calibration plot of absorbance on the y-axis and concentration on the
x-axis was constructed for the standard solutions. The plot was
constructed in Excel software. A straight line was expected due to Beer’s
law as explained earlier. However the law breaks down for higher
concentration solutions as dye aggregation may occur. A straight line was
drawn through the data points, and extended the line to intersect the
starting point. With the help of Excel software, the line can be found by
computer. Apart from this, the Excel could also calculate the formula of
the line of the calibration plot. In the form y=mx+b. This represents the
equation of the calibration line.
The absorbance of the unknown concentration solution is substituted into
100
the equation in the last step as y, and x can be solved. X represents the
concentration of the wash off solution. In this way, the concentration of
wash off solution can be obtained. Data is listed below.
Standard solution Concentration Absorbance
0.02g/L 0.35
0.025g/L 0.43
0.033g/L 0.56
0.05g/L 0.87
Table 4.1 Standard solution concentration at corresponding Absorbance.
It is clearly observed from Table 4.2 and Table 4.3 that the absorbance
values for wash off solutions are mainly located between 0.3 and 0.7.
Hence the standard solutions which are used to create calibration plot can
be selected. As can be seen from Table 4.1, the standard solutions which
were chosen represent the absorbance from 0.35 to 0.87. This absorbance
range is quite close to the range of wash off solution.
Calibration plot was constructed in Excel, as is shown in the graph below.
y = 17.36x - 0.0014 R² = 0.9991
0
0.2
0.4
0.6
0.8
1
0 0.01 0.02 0.03 0.04 0.05 0.06
Ab
sorb
ance
Standard solution concentration (g/L)
Absorbance VS Concentration calibration plot for standard solution
101
Figure 4.5 Standard solution plots
The equation of the calibration line is y=17.36x-0.0014; R2=0.9991. Both
equations indicate this line adheres the Beer’s law. The calibration line
equation can be simplified as y=17.36x since the absorbance should be 0
at concentration equal 0 g/L.
The absorbance of wash off solution was measured as described in
section 3.3, and the absorbances at the wavelength of strongest absorption
are shown below:
Wash off solution (not batched) Absorbance
0 g/L 0.63
Dicyandiamide 30 g/L 0.52
Dicyandiamide 60g/L 0.42
Dicyandiamide 90 g/L 0.46
Dicyandiamide 120 g/L 0.42
Dicyandiamide 150g/L 0.39
Cyanamide 30 g/L 0.54
Cyanamide 60 g/L 0.43
Cyanamide 90 g/L 0.45
Cyanamide 120 g/L 0.34
Cyanamide 150 g/L 0.29
Table 4.2 Absorbance at the wavelength of strongest absorption for wash off solutions (not batched)
Wash off solution (batched) Absorbance
0 g/L 0.51
Dicyandiamide 30 g/L 0.48
Dicyandiamide 60g/L 0.45
Dicyandiamide 90 g/L 0.40
Dicyandiamide 120 g/L 0.40
Dicyandiamide 150g/L 0.37
Cyanamide 30 g/L 0.37
Cyanamide 60 g/L 0.36
Cyanamide 90 g/L 0.36
Cyanamide 120 g/L 0.34
Cyanamide 150 g/L 0.30
Table 4.3 Absorbance at the wavelength of strongest absorption for wash off solutions (batched)
As seen in the Table 4.2 and Table 4.3, the absorbance y is known.
102
According to the equation of the calibration curve: y (absorbance)
=17.36x (concentration) -0.0014, the concentration x can be calculated.
As shown below.
Wash off solution (not batched) Concentration (g/L)
0 g/L 0.036
Dicyandiamide 30 g/L 0.030
Dicyandiamide 60g/L 0.024
Dicyandiamide 90 g/L 0.026
Dicyandiamide 120 g/L 0.024
Dicyandiamide 150g/L 0.022
Cyanamide 30 g/L 0.031
Cyanamide 60 g/L 0.025
Cyanamide 90 g/L 0.026
Cyanamide 120 g/L 0.020
Cyanamide 150 g/L 0.017
Table 4.4 Concentration for wash off solution (not batched)
Wash off solution (batched) Concentration (g/L)
0 g/L 0.029
Dicyandiamide 30 g/L 0.028
Dicyandiamide 60g/L 0.026
Dicyandiamide 90 g/L 0.024
Dicyandiamide 120 g/L 0.023
Dicyandiamide 150g/L 0.021
Cyanamide 30 g/L 0.021
Cyanamide 60 g/L 0.020
Cyanamide 90 g/L 0.019
Cyanamide 120 g/L 0.018
Cyanamide 150 g/L 0.017
Table 4.5 Concentration for wash off solution (batched)
All the wash off solutions were kept and volume measured by measuring
cylinder. Volume recorded as below.
Wash off solution (not batched) Volume (L)
0 g/L 0.42
Dicyandiamide 30 g/L 0.421
103
Dicyandiamide 60g/L 0.417
Dicyandiamide 90 g/L 0.418
Dicyandiamide 120 g/L 0.42
Dicyandiamide 150g/L 0.418
Cyanamide 30 g/L 0.415
Cyanamide 60 g/L 0.417
Cyanamide 90 g/L 0.418
Cyanamide 120 g/L 0.415
Cyanamide 150 g/L 0.421
Table 4.6 Volume measurement for not batched sample wash off solutions
Wash off solution (batched) Volume (L)
0 g/L 0.417
Dicyandiamide 30 g/L 0.425
Dicyandiamide 60g/L 0.42
Dicyandiamide 90 g/L 0.413
Dicyandiamide 120 g/L 0.415
Dicyandiamide 150g/L 0.422
Cyanamide 30 g/L 0.427
Cyanamide 60 g/L 0.419
Cyanamide 90 g/L 0.42
Cyanamide 120 g/L 0.417
Cyanamide 150 g/L 0.422
Table 4.7 Volume measurement for batched sample wash off solutions
As the concentration of wash off solution was presented in Table 4.4 and
Table 4.5, the dye being existed in wash off solution can be calculated.
Results are shown as below.
Wash off solution (not batched) Dye in wash off solultion (g)
0 g/L 0.0150
Dicyandiamide 30 g/L 0.0120
Dicyandiamide 60g/L 0.0102
Dicyandiamide 90 g/L 0.0110
Dicyandiamide 120 g/L 0.0101
Dicyandiamide 150g/L 0.0094
Cyanamide 30 g/L 0.0130
Cyanamide 60 g/L 0.0105
Cyanamide 90 g/L 0.0110
104
Cyanamide 120 g/L 0.0083
Cyanamide 150 g/L 0.0072
Table 4.8 Dye being existed in wash off solution (not batched samples)
Wash off solution (batched) Dye in wash off solultion (g)
0 g/L 0.012
Dicyandiamide 30 g/L 0.0119
Dicyandiamide 60g/L 0.0109
Dicyandiamide 90 g/L 0.0095
Dicyandiamide 120 g/L 0.0095
Dicyandiamide 150g/L 0.0092
Cyanamide 30 g/L 0.0091
Cyanamide 60 g/L 0.0087
Cyanamide 90 g/L 0.0087
Cyanamide 120 g/L 0.0083
Cyanamide 150 g/L 0.0073
Table 4.9 Dye being existed in wash off solution (batched samples)
From section 2.2, the concentration of dye used in each pad liquor (25
mL) is 10g/L. Hench each pad liquor containing 0.25g dye. Since the wet
pick up is 74%, the weight of each piece of cotton fabric is 4.45g. After
the padding process, the weight of padded sample fabric is 7.74g. In this
way, the weight gained, which is the pad liquor padded onto the fabric, is
3.29g. The weight of dye applied on cotton sample fabric is 0.025g.
The dye fixation can be calculated by the equation of the calibration line:
Fixation (%) = [(Dye applied –Dye washed off)/Dye applied]*100
As Table 4.8 and Table 4.9 have listed the weight of dye in wash off
solution, following the equation above, dye fixation under various
conditions can be obtained. Fixations are listed below.
Wash off solution (not batched) Dye fixation (%)
0 g/L 40
Dicyandiamide 30 g/L 52
Dicyandiamide 60g/L 59.2
105
Dicyandiamide 90 g/L 56
Dicyandiamide 120 g/L 59.6
Dicyandiamide 150g/L 62.4
Cyanamide 30 g/L 48
Cyanamide 60 g/L 58
Cyanamide 90 g/L 56
Cyanamide 120 g/L 66.8
Cyanamide 150 g/L 71.2
Table 4.10 Dye fixation for not batched samples
Wash off solution (batched) Dye fixation (%)
0 g/L 52
Dicyandiamide 30 g/L 52.4
Dicyandiamide 60g/L 56.4
Dicyandiamide 90 g/L 62
Dicyandiamide 120 g/L 62
Dicyandiamide 150g/L 63.2
Cyanamide 30 g/L 63.6
Cyanamide 60 g/L 65.2
Cyanamide 90 g/L 65.2
Cyanamide 120 g/L 66.8
Cyanamide 150 g/L 70.8
Table 4.11 Dye fixation for batched samples
Display the data in curves as below.
Figure 4. 6 Dye fixation for not batched samples
45
50
55
60
65
70
75
0 30 60 90 120 150
Fixa
tio
n (
%)
Catalyst concentration (g/L)
Dye fixation for not batched samples
Dicyandiamide
Cyanamide
106
Figure 4.7 Dye fixation for batched samples
Figure 4. 8 Dye fixation for Dicyandiamide under batch and not batch conditions
Figure 4. 9 Dye fixation for Cyanamide under batch and not batch conditions
50
55
60
65
70
75
0 30 60 90 120 150
Fixa
tio
n (
%)
Catalyst concentration (g/L)
Dye fixation for batched samples
Dicyandiamide
Cyanamide
50
55
60
65
70
75
0 30 60 90 120 150
Fixa
tio
n (
%)
Dicyandiamide concentration (g/L)
Dye fixation for Dicyandiamide
No batched
Batched
45
50
55
60
65
70
75
0 30 60 90 120 150
Fixa
tio
n (
%)
Cyanamide concentration (g/L)
Dye fixation for Cyanamide
No batched
Batched
107
Fig 4.6 and Fig 4.7 show the effects of increasing concentration of
dicyandiamide and cyanamide catalyst on dye fixation. Meanwhile Fig
4.8 and Fig 4.9 reveal the effects of the batching process on dye fixation.
The results given in Fig 4.6 and Fig 4.7 show that the degree of
synthesised phosphonic acid containing dye of the fixation is related to
the catalyst (dicyandiamide and cyanamide) concentration. Generally, the
higher the concentration of catalyst, the higher the level of dye-fibre
bonding that can be achieved. Good dye fixations are obtained when
concentration above 120 g/L of either catalyst are used. On the other hand,
the fixation of dye is specifically sensitive to cyanamide. In a manner of
speaking, the reaction of the cellulose with phosphonic acid containing
dye is more efficient in the presence of cyanamide as compared to that of
dicyandiamide.
Fig 4.6 and Fig 4.8 indicate that the batching step does not have
substantial effect on dye fixation in the high level catalyst concentration,
whether dicyandiamide or cyanamide are used. In the low level of
catalyst concentration, the batching step is seen promote the dye-fibre
bonding as indicated by a higher fixation value. This is in agreement with
the researchers where Gillingham says specifically what they have found
(Gillingham, et al. 2007). This phenomenon demonstrates that slow
diffusion is a possible factor that affects dye fixation. Since the
phosphonic acid containing dye consists of large molecule, high level
108
catalyst concentration will break down the dye molecule in aqueous
solution. Thus promoting the dye diffusion into cellulosic fibre and
resulting in high levels of dye fixation (Gillingham et al. 2007).
4.2.2 Effect of Catalyst type and Concentration on dye
fixation via Inkjet printing
As mentioned in section 3.1, the total colour difference is measured by
spectrophotometer. TheΔL* indicates lightness difference. The results are
shown below.
Cyanamide concentration Blank area (L*) Jetprinted area (L*) ΔL*
0 g dm-3
92.99 70.45 22.54
30 g dm-3
93.02 65.41 27.61
60g dm-3 92.78 66.62 26.16
90g dm-3
92.65 60.46 32.19
120g dm-3
92.65 61.08 31.57
150g dm-3 91.46 56.05 35.41
Table 4.12 Lightness for inkjet printing samples treated with Cyanamide
Dicyandiamide concentration Blank area (L*) Jetprinted area (L*) ΔL*
0 g dm-3
92.99 70.45 22.54
30 g dm-3 92.49 66.26 26.23
60g dm-3
93.19 68.5 24.69
90g dm-3
93.29 67.13 26.16
120g dm-3
92.83 65.42 27.41
150g dm-3
93.42 66.74 26.68
Table 4.13 Lightness for inkjet printing samples treated with Dicyandiamide
For the sake of direct display and more detailed, convert the Table 4.12
and Table 4.13 to diagram.
109
Figure 4.10 Colour difference of inkjet printed samples
As can be seen from Fig 4.10, the inkjet printed cellulosic samples show
the same trend as the samples treated by the pad-bake application method.
Normally, the lightness of phosphonic acid containing dye treated cotton
is proportional to the catalyst (dicyandiamide and cyanamide)
concentration. The higher the concentration of catalyst, the lower the
lightness that can be achieved. Since in CIE L*a*b* system, L* is a
measure of the lightness of an object and ranges from 0 (black) to 100
(white), lower values of L* indicate darker shades. Hence L*can also be
related to the degree of dye fixation. The reaction of the cellulose with
phosphonic acid containing dye is thus seen more efficient in the
presence of cyanamide than in the presence of dicyandiamide also for
inkjet printing application.
Actually it is seen in the literature that the performance of
cyanamide/dicyandiamide-phosphonic acid containing dye reaction is still
debated. In this research, cyanamide has superiority to dicyandiamide.
20
25
30
35
40
0 30 60 90 120 150
ΔL*
Catalyst concentration (g/L)
Colour difference of inkjet printed samples
Cyanamide
Dicyandiamide
110
Early researches have explored the role of cyanamide in the dye-fibre
bonding reaction. One proposal is that cyanamide will promote
phosphonic anhydride intermediate formations shown in Fig 4.11.
Figure 4.5 Anhydride formation from a phosphonic acid dye in the presence of cyanamide & reaction
of the said anhydride with cellulose (Dye represent the chromophore and cell represent cellulose
residues).
Apart from this marked action, it has also been proposed that the dye
could generate free phosphonic acids undertake thermal dissociation and
then react with cyanamide to give a cationic adduct (Amato et al. 1987),
as shown in the Fig 4.12 below.
Figure 4.6 Reactive cationic intermediate formation from a phosphonic acid dye in the presence of
cyanamide & reaction of the said adduct with cellulose (Dye represents the chromophore and cell
represenst cellulose residues).
For dicyandiamide, the fixation mechanism of phosphonic acid dye to
cellulose is simplified in Fig 4.13 (Renfrew and Taylor, 1990).
111
Figure 4.7 Mechanism of phosphonic acid dye to cellulose via dicyandiamide catalyst (Cell represents
the cellulose residues).
Dicyandiamide could also react with the free phosphonic acids generated
from the dye. The mechanism would be identical as that presented in Fig
4.13.
As reviewed in section 1.1.2.3, the reaction of the phosphonic acid dye
with cellulose is basically an esterification process that result in the
cross-linking of cellulose molecules between dye and cellulose via a
reaction with cyanamide/dicyandiamide. The cross-links are a type of
phosphonic acid ester. Essentially speaking, the extent of esterification
that has been achieved determines the extent of dye fixation onto the
cellulosic fibre. From the above, a feasible reason why cyanamide
performs more efficiently than dicyandiamide in inducing dye fixation is
the low yields of phosphonic acid ester obtained in the presence of
dicyandiamide compared with cyanamide.
Another possible interpretation could be that compared with
dicyandiamide, cyanamide is a relatively low molecular weight
compound. The molecular weight of cyanamide is 42.04 g/mol,
112
meanwhile the molecular weight of dicyandiamide is 84.08 g/mol.
Furthermore dicyandiamide is comparatively hydrophobic and has low
water solubility at room temperature. However, Cellulose is hydrophilic.
As a result, the cellulose may take up less dicyandiamide from solution
during the application process. Molecular size is known to be a vital
factor in dye diffusion. Additionally, the catalyst-dye adduct must exist
inside the fibre prior to dye-fibre bonding (Burlington Industries Inc,
1978) It may be that the adduct is first formed, in which case a
dye-cyanamide adduct may be expected to have higher diffusivity due to
lower molecular weight than a dye-dicyandiamide adduct. Alternately,
both dye and catalyst may react in situ. In such case, the substantivity of
the catalyst, and hence possibly their solubility, will be relevant. In this
way, cyanamide can be more effective in promoting the dye-fibre
bonding.
Cyanamide not only acts as a catalyst for dye fixation but also plays a
role in enhancing dye solubility during the dyeing process when dye
diffusion is occurring.
4.2.3 Effect of printing method on colour strength
According to the visual observation and colour strength test from
spectrophotometer (Fig 4.14 and Fig 4.15), the inkjet printed cellulosic
samples show a clear increase in colour strength (L*) as compared to the
padded samples. At the same catalyst concentration level, inkjet printed
113
fabric always consistently higher lightness compared with padded fabric
(Lower value of L* stands for darker shade). A couple of interpretation
could explain why this happen.
Figure 4.8 Lightness VS Cynamide concentration
Figure 4.9 Comparison between inkjet printing sample (left) and pad-bake sample.
As mentioned in section 1.1.2.2, inkjet printing is a non-contact
technology. By projecting tiny drops of liquid ink onto the cellulosic
substrate, image formation can be achieved through dye fixation taking
place in fibre. A single DOD drop deposited on cotton fabric is knows to
be only 41.6 picoliter (Carr et al. 2008). Thus, only very small amount of
dye applied is on cotton through each printing. As seen in a micrograph
50
55
60
65
70
75
80
85
0 30 60 90 120 150
L*
Cyanamide concentration g/L
Lightness
Jetprinted fabrics
Padded fabrics
114
taken by SEM (Fig 4.16), a single drop is about 2 to 3 fibres size (Carr et
al. 2008). The fibre size is approximately 20μm. This indicates the
relative size of the ink drops. Nonetheless, as in inkjet printing, brilliant
and sharp colour is obtained by dye molecules fixed on or near the
substrate surface (H. Ujiie, 2006).
Figure 4.10 Ink distribution in cotton fibre (Inkjet deposition of complex mixtures to textiles, 2008)
As the number of drops increased, the ink spread along the fibre direction
as opposed to the transverse direction. The drop distribution on cotton is
affected by the yarn direction and interactions. From Fig 4.17, it is clearly
to see that the accumulated ink drops prefer to stay on one yarn until
excess ink moved to neighboring yarns (Carr et al. 2008). With the help
of optical microscope, it is observed that drops spread along the yarn weft
and weft direction rather than the transverse direction.
115
Figure 4.11 Drops deposited on the cotton fabric(Inkjet deposition of complex mixtures to textiles,
2008) .
In the padding process, the sample fabric is evenly impregnated.
Specifically, the pad liquor is decanted into the padding trough, and
cotton fabric was fed in to squeeze roll. The uniform expression of the
pad liquor was achieved by passing the cotton fabric through the arranged
rolls, as cotton emerged from the trough. Under the pressure, dye
molecules could diffuse into cellulose fibre quite quickly and deep in
both fibre direction and transverse direction. Fibres act as a kind of
barrier for dye spreading in the transverse direction. Whereas in the
padding process, pressure and aqueous solution would facilitate dye
transport further into the fabric. To put it briefly, dye used in padding
process would transport into internal or core yarns of the fabric, or even
exist within the gap between neighboring yarns.
116
The penetration of the ink into the fabric will influence the colour
strength and print quality. In accordance with the studying of Kaimouz
(Kaimouz et al. 2010), increase ink penetration into fabric would result in
the decrease in the visual colour strength. Compared with inkjet printed
fabric, padded cellulosic fabric possesses higher degree of dye
penetration. For inkjet printing, less penetration into the fabric results in
most of the dye located on the fabric surface or the upper layer of the
substrate. Thus stronger color can be achieved.
Apart from the dye location, catalyst padded on cellulosic substrate prior
inkjet printing also affect the colour strength. As all the samples were
padded with sample level of dicyandiamide /cyanamide, the amount of
catalyst deposited on cellulosic fabric is equal. As discussed in the above,
only a small amount of dye is deposited on the surface or upper level of
fabric for inkjet printed samples. Under the same catalyst concentration
conditions, it is proposed that more catalyst would be available to
promote dye-fibre bonding reaction in the upper level of inkjet printed
cellulosic substrate. For padded cotton samples, dye deposited not only
on the surface but also in the core fibre. Hence the ratio of Catalyst to dye
for inkjet printing is much higher than that in padding application.
Furthermore, a steady increase in dye fixation with increased catalyst
concentration can be observed (Fig 4.14). Hence it is probable that an
increase in effective catalyst: dye ratio is the reason why inkjet printing
117
actually performs higher visual depth degree of fixation under the same
level of catalyst.
Further, additional experiments in laboratories have supported this
contention. For example, the lightness of inkjet printed sample under
different cyanamide concentration indicates the increase of catalyst
concentration would result in the decrease of L*, as seen in Fig 4.18.
Lower value of L* stand for darker shade. L* is a measure of the
lightness of an object and ranges from 0 (black) to 100 (white).
Figure 4.12 L* for inkjet printing via Cyanamide
As we can see from the trendline from Fig 4.18, we are not yet reaching a
plateau level at concentration of 150 g/L. This trendline has a good fit and
shows the potential for further development: higher catalyst concentration
result in lower colour strength. In section 4.2.1, Fig 4.6 and Fig 4.8 show
the relationship between catalyst concentration and fixation through
pad-bake method. As we can see that the fixation line flat out as increase
in catalyst concentration. However in inkjet printing the direct
y = -0.0868x + 69.856 R² = 0.8982
40
45
50
55
60
65
70
75
0 30 60 90 120 150
L*
Concentration (g/L)
Cyanamide
118
relationship indicates that the shade would get darker when the
concentration of catalyst keeps increasing. This also strengthens the
argument above that in inkjet printing the higher catalyst to dye ratio can
be achieved.
Further investment could keep on trying how higher catalyst
concentration may affect the colour strength.
4.3 Effect of pretreatment and baking process on tensile
strength
As mentioned in section 3.2, five pieces of specimen were tested via
Instron tensile test machine. As seen in Table 4.14.
Pretreated Printed with phosphonic acid
containing dye
baked Wash off
sample 1 Cyanamide √ √ √
sample 2 Dicyandiamide √ √ √
sample 3 / √ √ √
sample 4 / √ √
sample 5 / √
Table 4.14 Sample preparation
This test was designed to assess the effects of dye application on strength
retention of the cotton substrate. Especially investigate will dye and bake
process affect tensile strength during printing process.
As seen in Fig 4.19, three samples were printed via inkjet printing. One
sample was not pretreated with catalyst, and displays a higher value of
tensile strength. From this point, pretreatment on cotton prior to printing
119
contributes to lowering the strength level.
Figure 4.19 Tensile strength for print-bake samples
The effect of short thermal treatment on cotton tensile strength can be
seen from Fig 4.19. The tensile strength actually remains intact after the
samples are thermally treated for a short time (less than 4 min). A less
than 4% loss in tensile strength could associate with small changes in the
fine physical structure of cellulose. Early researches demonstrate that
during the thermal treatment cellulose undergoes decrystallization and
recrystallization. Loosening of the cellulose structure may alter surface
friction and the interaction of the fibres and yarns which make up the
structure (Hebeish et al. 1979). The magnitude of tensile strength loss is
dependent on the temperature and duration. Cotton fabric can be handled
at the relatively high temperatures (approximately 180ºC) in a short time
without immediate catastrophic damage occur.
From Fig 4.18, compared with baked only sample (no pretreatment and
printing process), the printed and pretreated samples show low level of
9
9.5
10
10.5
11
11.5
12
Sample 5 Sample 4 Sample 3 Sample 2 Sample 1
N/m
2 Tensile Strength (N/m2)
Tensile Strength
120
tensile strength. This phenomenon demonstrates that the phosphonic acid
dye surely tenderized cotton fabric and result to strength reduction. We
thus propose that the strength loss observed in the printed samples is
associated with dye fixation. As mentioned in section 1.1.2.3 and 1.1.2.4,
dye-fibre bonding formed after dye applied on cotton fabric surface. The
reaction between dye reactive group and reactive site on cellulosic fibre
would affect the degree of polymerization and slightly change the fine
physical structure of cellulose fibre. Thus a decrease in the degree of
polymerization could occur and result in a loss in tensile strength. The
below table shows the relationship between inkjet printed fabric colour
strength and tensile strength.
Colour strength (L*) Tensile strength
(N/m2)
Pre-treat with Cy and inkjet print 56.05 9.81
Pre-treat with Di and inkjet print 66.74 10.29
No pre-treat & print (bake only) 93 11.32
Table 4.15 Tensile strength
Convert this Table 4.15 to plot, as shown in Fig 4.20.
121
Fig 4.20 Tensile strength VS Colour strength
Fig 4.20 clearly indicate that a level of proportionality commensurate.
Cotton fabric pre-treated with cyanamide displays the best performance
and thus has the highest tensile strength loss.
Our aim in inkjet printing was to limit dye deposition to the surface.
Hence we presume that the damage to cellulosic substrate observed via
the tensile strength loss is similarly to the surface of the fabric. Although
a significant degree of tenderizing was presumably achieved totally, the
overall integrity & tensile strength of the fabric is not compromised.
Finally, resulting to acceptable levels of strength loss.
9.81
10.29
11.32
9.6
9.8
10
10.2
10.4
10.6
10.8
11
11.2
11.4
0 20 40 60 80 100
Ten
sile
str
en
gth
(N
/m2 )
Colour strength (L*)
122
5. Conclusion
The aim of this research was an investigation of the influence of
phosphonic acid group in dye-fibre bonding between modified reactive
dye and cellusic fabric, via a pad-bake process to yields suitable
conditions for subsequent inkjet printing. A commercial dichloro-triazine
dye (Blue MX-2G) was selected as the original dye, and through
chemical reaction a new phosphonic acid containing dye was synthesised.
Compared with the MX-2G, phosphonic acid groups were added on the
reactive system. The sodium salt of the original dye was converted to the
ammonium salt. The synthesised phosphonic acid containing dye was
applied to cotton via pad/pad-batch-bake process and subsequent inkjet
printing process at varying amount of the catalyst (Dicyandiamide and
Cyanamide). One half of each padded sample was batched prior to drying
process. Washing off process was carried out on all padded and printed
samples. Dye fixation and colour strength were measured and the results
are shown in Table 4.10, 4.11, 4.12 and 4.13. The influence of modified
dye on cotton fabric was also assessed by Tensile Test, results are
displayed in Fig 4.17 and 4.18.
Results of the investigation led to the following conclusions:
Based on the analysis on Fig 4.3 and Fig 4.4, phosphonic acid containing
dye can be synthesised. Cl atom can be substituted by phosphonic acid
group through the method used in this research. Using the existing
123
synthetic method, phosphonic acid group can be introduced to certain
commercial dye.
Batching process used prior drying had a small effect on dye fixation
promotion at high dicyandiamide and cyanamide concentration (above
120 g/L). Under low catalyst concentration conditions, the large dye
molecules diffused into cellulosic fibre at slow migration. While higher
catalyst concentration can significantly improve the dye diffusion process.
In this way, high concentration of catalyst would be advantageous for
pad-bake process.
The dye fixation results clearly demonstrate that the covalent bonding
between dye and fibre is sensitive to catalyst concentration. By
incorporating cyanamide/dicyandiamide in the padding solutions, the
padded sample fabrics offer higher level of dye fixation than non-catalyst
treated cotton fabric. The same phenomenon happened on inkjet printed
fabrics, as the pre-treated catalyst containing samples offer higher level of
dye fixation. As the increase in catalyst concentration, the rise in dye
fixation can be seen according to the results depicted in Fig 4.6, 4.7, 4.8
and 4.9. Pad-bake method and inkjet printing both present this trend.
Cyanamide always displays a better performance in both pad-bake
process and inkjet printing. As analysed in section 1.1.2.2, the phosphonic
acid groups other electron donatting groups are pivotal parameters in
influencing the dye fixation level and the colorimetric data of the
124
phosphonic reactive dye and dye-based ink on cellulosic substrate.
Possible explanation is that cyanamide probably promotes the generation
of the free acids during baking, leading to cations from the dye counter
the negative charged cellulosic fibre and thus more and more dye anions
absorbed on the fabric. Eventually promote the esterification between
dye-fibre reactions and offer a relatively high level of dye fixation.
Under the same level of dye and catalyst applied on cotton fabric, inkjet
printing method offered a higher level of colour strength when compared
with pad-bake method. This phenomenon could attribute to the dye
molecules are mainly deposited on the surface or upper level of cellulosic
fabric through inkjet printing, as in pad-bake process dye molecules are
penetrated in bulk of cellulose fibre. Since the dye molecules through
padding process were distributed in both yarn direction and transverse
direction, dye-fibre bonding happened not only on the surface of fabric,
but also in the interior yarns. It is clearly to see the darker shade of inkjet
printed fabric is only appeared on face side, meanwhile both sides of the
padded fabric appeared lighter shade.
The tensile test results indicate the phosphonic acid containing dye will
damage cotton fabric slightly. Since the tensile strength of printed fabric
is lower than the unprinted and the plain cotton samples. The reduction of
tensile strength is within an acceptable range.
However, the drawback to this phosphonic acid containing dye is that dye
125
fixation is dependent on the concentration of catalyst. Only high
concentration of cyanamide or dicyandiamide can present high dye
fixation value.
5.1 Recommendations for future research
In this research, it is shown that the phosphonic acid containing dye can
be converted, and some objectives are achieved. However, there are some
recommendations for further research and development.
Even the dye was converted as expect, improvement in synthetic method
to achieve better conversion can be investigated.
Depending on the research of effect of catalyst concentration, future
investigates in how high level catalyst concentration result in high
fixation could be carried out.
Apart from these two points, the use of thickener in pre-treatment to
prevent or minimum the cellulosic substrate damage from dye-fibre
reaction. Hold on the ink where it drops and keep the dye in the surface,
thus the cotton affected by the reaction is minimum. This is worth for the
further study.
As in this research, wash fastness has never been assessed. As a matter of
fact, wash fastness is a quite important factor in dye applying process.
The future research could carry out the wash fastness assessment on dyed
and printed fabrics. Such assessment would provide the loss and change
of colour in the washing process by a consumer and the lighter portion
126
that may be washed with it.
5.2 Future of Inkjet printing
Inkjet printing is one of the states of printing technique in textile market,
available in terms of quality, productivity assured reproducibility in spite
of initial high investments. It can speed up the process between design
and industrial production. Meanwhile, the first time Just In Time
production can be realized through this technology. That way huge
reduced concept-to-consumer time frames can be achieved, all level
inventory risk and high level stock could be avoid as a result. The
competition between inkjet printing and conventional printing will
continue. Conventional printing will keep up to be used in textile industry
where the products are produced in long runs and time-to-market is not a
critical issue. In the meantime, inkjet printing will aim to premium textile
market, customized textile products and for the products where
time-to-market is critical.
127
6. Reference
1. Franco Phj & Valadez-gonzalezM. (2005), ―Fibre-matrix adhesion in
natural fibre composites". In Mohanty, A.K.Natural fibres,
biopolymers and biocomposites, CRC, Boca Raton, p.37.
2. S. Gordon & Y-l. Hsieh (2007), Cotton: science and
technology, Woodhead, Cambridge.
3. P. J Wakelyn (2007), Cotton fiber chemistry and technology,CRC,
Boca Raton.
128
4. Art Quill Studio (2014). Cellulosic Fibers (Natural) – Cotton Art
Resource. Available from:, The Education Division of Art Quill & Co.
Pty. Ltd. Web site:
http://artquill.blogspot.com.au/2014/02/cellulosic-fibers-natural-cotto
n-1-3.html [Accessed: April 29, 2014].
5. Cousey H. a & Smith S.b (1996), The Formation and Structure of a
new Cellulose Fibre, Lenzinger Bericht, pp.51-63.
6. Leslie Mile, W. C. (2003), TEXTILE PRINTING, 2nd ed, Society of
Dyers and Colourists, Manchester. pp. 1.
7. Robert R Mather & Roger H Wardman (2011), The Chemistry of
Textile Fibres, The Royal Society of Chemistry, p.23.
8. M. Sfiligoj Smole, S. Hribernik & K. Stana Kleinschek (2013), "Plant
Fibres for Textile and Technical Applications". In Advances in
Agrophysical Research, InTech, p.373.
9. Xiangwu Zhang (2014). Fundamentals of Fiber Science, DEStech
Publications, pp.65-68.
10. Aleen G. Cohen & Ingrid Johnson (2012), "Yarns and Sewing
Threads". In Fabric Science, Fashion Institute of Technology, New
York, pp.69-73.
11. Julie Parker (1998), All About Cotton: A fabric dictionary and
swatchbook, 2nd ed, Rain City Publishing, Seattle, p. 10.
12. Phillip J. Wakelyn, Barbara A. Triplett & J. Vincent
129
Edwards(2007), Cotton fibre Chemistry and Technology,3rd ed, CRC
Press, Boca Raton, p. 63.
13. K. Stana-kleinschek & V. Ribitsch (1998), "Electrokinetic properties
of processed cellulose fibers". In Colloids Surfaces A: Physicochem,
pp.127-138.
14. Klemm D, Heublein B & Fink H-p (2005), "Cellulose: Fascinating
Biopolymer and Sustainable Raw Material",Angewandte Chemie
International Edition, vol. 44, no. 22, pp. 3358-3393.
15. Maya Jacob John & Sabu Thomas (2008), "Biofibres and
biocomposites", Carbohydrate Polymers, vol. 71, no. 3, pp. 343-364.
16. Robert J. Moon, Ashlie Martini & Jeff Youngblood (2011), "Cellulose
nanomaterials review: structure, properties and
nanocomposites", Chemical Society Reviews, vol. 40, no. 7, pp.
3941-3994.
17. Gordon S & Hsieh Y-l (2007), "Chemical structure and properties of
cotton". In Cotton: Science and Technology, WoodheadPublishing,
UK
18. R. H. Attala and A. Isogai (2005), Recent developments in
spectroscopic and chemicalcharacterization of cellulose, Marcel
Dekker, New York. pp123-157.
19. Fink, H.-P, Walenta, E. (1994) ―Röntgenbeugungsuntersuchungen zur
übermolekularen Struktur von Cellulose im Verarbeitungsprozeß‖,
130
Papier 48, pp. 739-748.
20. John Mj, Thomas, S (2008), "Biofibres and
biocomposites",Carbohydr. Polym, vol., no. 71, pp. 343-364.
21. Moon Rj, Martini A, Nairn J, Simonsen J, Youngblood J (2011),
"Cellulose nanomaterials review: structure, properties and
nanocomposites", Chem. Soc, no. 40, pp. 3941-3994.
22. Hult E-I, Iversen T, Sugiyama J (2003), "Characterization of the
supermolecular structure of cellulose in wood pulp fibres", Cellulose
10, vol., pp. 103-110.
23. Kim U-j, Eom SH, Wada M (2010), "Thermal decomposition of
native cellulose: Influence on crystallite size", Polym. Degrad. Stab,
no. 95, pp. 778-781.
24. Hardy BJ, Sarko A (1996)‖ Molecular dynamics simulations and
diffraction-based analysis of the native cellulose fiber: structural
modeling of the Iα Iβ
Polymer, no, 37, pp1833-1839.
25. Rattee, I. D. & W. Stephen, (1956), British Patents 772030,774925,
and 781930 (to ICI Ltd.).
26. David M Lewis (1998), "Dyestuff–fibre interactions",Coloration
Technology , vol. 28, no. 1, pp. 12-17.
27. Arthur D Broadbent (2001), Basic Principles of Textile Coloration,
Society of Dyes and Colourists, pp332-333.
131
28. John Shore (2002), "Colorants and auxiliaries.‖ Society of
Dyers and Colourists, vol. 1, pp. 358-360.
29. John Shore (1995), Cellulosics Dyeing, Society of Dyers and
Colourists,pp193-194.
30. T E Peacock (1965), Electronic properties of aromatic and
heterocyclic moledules, London Academic Press, pp103
31. J Shore (1990), Colorants and Auxiliaries: Vol 1. Published by
Society of Dyers and Colourists, Bradford.
32. Peter J. Dolby (1977), "The dyeing of fibres with reactive dye".
In International dyeing symposium, Practical dyeing problems,
A.A.T.C.C, pp.25-26.
33. John Shore (2002), Colorants and auxiliaries: Organic chemistry and
application properties, Society of Dyers and Colourists, pp.363-365
34. Zollinger. H (1991), Color Chemistry, VCH, Weinheim, p227.
35. John Shore (1995), Cellulosic Dyeing, Society of Dyers and
Colourists, pp225-226.
36. Leslie. W. C. Miles (2003), Textile Printing, 2nd , Society of dyers
and colourists, pp301-303.
37. A Teunissen, M Kruize and M Tillmanns (2002), Developments in the
Textile Printing Industry, Boxmeer: Stork Textile Printing Group.
38. Ross T (2004), A primer in digital textile printing. Available from:
http://www.techexchange.com/thelibrary/DTP101.html [Accessed:
132
May 9, 2014].
39. Chris Byrne (2001), Inkjet Printing in the Textile Industry: Drawing
up the Battlelines. Available from:
http://www.digitaltextile.net/archive/articles/overview2001.html
[Accessed: May 9, 2014].
40. K Venkataraman (2012). The Chemistry Of Synthetic Dyes V6:
Reactive Dyes, Elsevier: London, pp409-410.
41. Alexandre Paprocki, Heldiane S. Dos Santos & Marta E.
Hammerschitt, 2010, Ozonation of azo dye acid black 1 under the
suppression effect by chloride ion. Journal of the Brazilian Chemical
Society, 21(3).
42. B. L. Mcconnell, L. A. Graham & R. A. Swidler, 1979, A New
Reactive System for Continuous Dyeing and Printing of Cellulose and
Blends. Textile Research Journal, 49, pp.458.
43. A. Soleimani-Gorgani, M. Pishvaei (2011), Water fast ink Jet print
using an acrylic /nano-silver ink, Color Colorants Coat, pp79-83.
44. S. O. Aston, J. R. Provost, H. Masselink (1993), Jet printing with
reactive dyes, J. Soc. Dyers Color., vol 109, pp147-152.
45. B. Glover (2005), Reactive dyes for textile printing, Colorage,
pp67-82.
46. Holly Brackmann (2006), The Surface Designer's Handbook,
Interweave Press, pp 15-16
133
47. Harold S. Freeman, Leon S. Moser & Wilson M. Whaley, 1988, New
Phosphonic Acid Reactive Dyes for Cotton. Dyes and Pigments , 9
pp.57-65.
48. Douthwaite, F. J. N. Harrada, T. Washimi (1996), Proceedings
IFATCC Conference, Vienna, pp447-451.
49. ID Rattee and M M Breuer (1994), The Physical Chemistry of Dye
Adsorption, Academic Press, London, p. 182.
50. Schneider R (2004), "Minimization of water consumption in
European textile dyeing and printing industry using innovative
washing and recycling technologies". InInnowash econfidential
progress reports of EU project.
51. P. Moulin, M. Maisseu, F. Charbit (2006), "Treatment and reuse of
reactive dyeing effluents,Journal of Membrane", Science, vol. 269, no.
pp. 15-34.
52. Jane Spencer (2007), Available from:
http://online.wsj.com/news/articles/SB118580938555882301
[Accessed: April 9, 2014].
53. A H M Renfrew, J a Taylor (1990), "Cellulose Reactive Dyes: Recent
Development and Trends", Journal of the Society of Dyers and
Colourists, vol. 20.
54. M E Amato, S Fisichella and I D Rattee (1987), "The dyeing of cotton
with phosphonic reactive dyes in alcohols",Issue Journal of the
134
Society of Dyers and Colourists Journal of the Society of Dyers and
Colourists, vol. 103, no. 12, pp. 434-437.
55. Tincher WC & Hu Q (1996), Recent progress of inkjet technologies II.
The Society forImaging Science & Technology’s Publication, pp.
366–369.
56. Mineral Adsorbents (2014), Filter Agents and Drying Agents.
Available from:
http://www.sigmaaldrich.com/chemistry/chemical-synthesis/learning-
center/technical-bulletins/al-1430/molecular-sieves.html [Accessed:
June 4, 2014].
57. Siladitya Behera*, Subhajit Ghanty, Fahad Ahmad, Saayak Santra,
and Sritoma Banerjee (2012), UV-Visible Spectrophotometric Method
Development and Validation of Assay of Paracetamol Tablet
Formulation, Department of Quality Assurance and Pharma
Regulatory Affairs, Gupta College of Technological Sciences, West
Bengal, India.
58. Kan, C.W., Chan, K. and Yuen, C.W.M (2000), ―Application of low
temperature plasma on wool - Part III: Surface Chemical and
structural composition‖, The Nucleus, 37(3-4), pp. 145-159.
59. R. M. Silverstein, F. X. Webster (1998), Spectrometric Identification
of Organic Compounds, 6th
edition, Wiley, New York.
60. T. W. G. Solomons, C Fryhle (2001), Organic Chemistry, 7th edition,
135
Wiley, New York.
61. Manfred, H., Meier, H. and Zeeh, B. (1997), Spectroscopic Methods
in Organic, Chemistry, New York: George Thieme.
62. Lambert, J.B., Shurvell, H.E., Lightner, D.A. and Cooks, R.G. (1998),
Organic Structural Spectroscopy, N.J.: Prentice Hall.
63. O. Thomas & C. Burgess (2007), UV-visible spectrophotometry of
water and wastewater, Elsevier, Amsterdam.
64. M E Amato, S Fisichella and I D Rattee(1987), ―The dyeing of cotton
with phosphonic reactive dyes in alcohols‖, J.S.D.C., 103, p. 434
65. A H M Renfrew & J a Taylor (1990), "Cellulose reactive dyes:recent
developments and trends", Rev. Prog. Coloration, vol. 20, pp. 5-8.
66. Estelle L Gillingham, David M Lewis, Asfia Nabi and Kawee
Srikulkit (2007), "Triazinylamino-alkylphosphonate reactive dyes for
cellulosic fibres", Society of Dyers and Colourists. no. 123, pp.
178-183.
67. BurlingtonIndustries Inc (1978), BP 1 514 395.
68. H. Ujiie (2006), Digital printing of textiles, Woodhead Publishing
Limited, Cambridge, pp 255-257.
69. W.W. Carr, D. G. Bucknall, J. F. Morris (2008), ―Inkjet deposition of
complex mixtures to textiles‖ in National Textile Center Annual
Report.
70. A W Kaimouz, R H Wardman and R M Christie (2010), ―Ink-jet
136
printing process for lyocell and cotton fibres. Part 2: The relationship
of colour strength and dye fixation to ink penetration‖, Coloration
Technology, vol 126, pp342-347.
71. A. HEBEISH, A. T. EL-AREF, E. A. EL-ALFI, and M. H.EL-RAFIE
(1979), ―Effect of Short Thermal Treatment on CottonDegradation‖,
Textile Research Division, National Research Centre, Dokki, Cairo,
Egypt, pp. 454-462.
7. Appendix