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An investigation of the addition of nicotinic acid, as a catalyst, to the pad
liquor of a one-pass process for the continuous dyeing of polyester/cotton
blends.Presented by
DR ARSHAD MEHMOOD
Textiles & Paper, School of MaterialsThe University of Manchester,
Manchester, UK
Email: [email protected]
Undertaking general contract chemical synthesis. Undertaking chemical research in colour-related areas (e.g.
textiles, paper, new ink jet applications etc). Providing consultancy on colour-related topics. Providing specialist (coloured) test fabrics for use in laundering
protocols.
The study was conducted at the University of Manchester under the Supervision of CSS
Introduction of CSSColour synthesis solutions Ltd. is based at Hexagon Tower, Blackley, Manchester, UKwww.coloursynthesissolutions.co.uk
The main features of CSS’s business are as follows.
Catalytic quantities of tertiary amines, for example trimethylamine, N,N-dimethylhydrazine, pyridine and substituted pyridine such as nicotinic acid etc. were used to take advantage of this enhanced reactivity.
Background of the Study
In 1959, chemists at ICI showed that a series of tertiary amines can react with monochlorotriazines, the important observation was made that the quaternary ammonium products fixed more rapidly to cellulose than the chloro precursors.
Dawson in1964, reported that the tertiary amine is an easier leaving group than the chloride ion. Additionally, due to an extra positive charge, the quaternised dye exhibits a greater substantivity, for cellulosic fibres, than the parent MCT dye.
In 1987, ICI launched the Procilene N range products for polyester/mercerised cotton printing, which employed nicotinic acid as a catalyst in the print pastes to allow fixation to take place under neutral conditions, thereby protecting the disperse dyes from alkaline degradation.
Dyes containing quaternary ammonium
reactive group
N N
N NHR
N
CO2
NH
Dye
+
N-O2C
N N
N
NHC2H4HN
NHR
N
O
O
NSO3Na Cl
Cl SO3Na
NHC2H4HN
N
N
N
NHR NCO2
+
+
In 1979, ICI launched Procion Blue H-EG (C.I. Reactive Blue 187), the first reactive dye carrying a quaternary ammonium reactive group
In 1984, Nippon Kayaku introduced a range of bis-s-triazinyl reactive dyes, the Kayacelon Reacts, which also utilised 3-carboxypyridine (nicotinic acid) as the leaving group.
Nicotinic acid was added to the pad liquor of the one-pass continuous dyeing process, to allow in-situ formation of the quaternary species, which, being more reactive than the parent dye, would be expected to react with cellulose more quickly and, possibly, more efficiently. This would allow a higher colour yield on unmercerised cotton than that obtained from the parent reactive dyes.
Aim of the Current Study
R3N
NR3
X
NN
NCl
O R3NCell -
NR3
X
NN
N
X
ClN
NN
O-Cell
X
NN
N
Dye-NH Dye-NH+
+ +
Dye-NH+ +Dye-NH+
X = usually a substituted arylamino group
PAD LIQUOR INCLUDES:
o REACTIVE DYE y g/lo MIGRATION INHIBITOR 10-20 g/lo WETTING AGENT 2-4 g/lo SEQUESTERING AGENT 0-4 g/lo FIXATION ASSISTANT 15 g/lo ALKALI (SODIUM BICARBONATE) 2-10 g/lo PAD LIQUOR TEMPERATURE 20-30oCo NICOTINIC ACID 30
g/l
One-Pass Continuous Dyeing process
Padder
I.R. pre dryer to reduce moisture to
50% Wash off
Drying 1’@110’C
Thermofixation 1’@210’C
Investigation of the addition of nicotinic acid to the pad liquor of one-pass process.(PROCION PX DYES)
Investigation of the addition of nicotinic acid to the pad liquor of one-pass process.(LEVAFIX CA DYES)
0
4
8
12
16
20
0 10 20 30 40 50
K/S
Depth applied(g/l)
(b)
0 g/l Na
30 g/l NA
0
1
2
3
4
5
6
0 10 20 30 40 50
K/S
Depth applied (g/l)
(a)
0 g/l NA
30 g/l NA
0
5
10
15
20
25
30
0 10 20 30 40 50
K/S
Depth applied (g/l)
(c)
0 g/l NA
30 g/l NA
Reasons for the Poor Performance of
the Reactive Dyes with Addition of Nicotinic Acid
(ii) the nicotinic acid derivative, once formed, exhibited a lower degree of chemical selectivity with the cotton under the one-pass continuous dyeing process conditions.
This could be due to one of two reasons, viz either
(i)insufficient time to convert the parent dye to its more reactive derivative. Or
Investigation of the 1st possible cause
Fixation/Dye speciesRetention time (tR) by HPLC
(Determined by prepared standards)
After 30secs Drying
After 60secs Drying
After 30secs Thermofixation
After 60secs Thermofixation
Fixation (%) 3 4 30 38
Parent (MCT) dye (%) 4.96 63 61 37 28In-situ formed3-carboxypyridinium triazine dye (%)
2.19 20 19 15 12
Hydrolysed dye (%) 3.28 14 16 18 22
Increase in dyeing time scale
Chromatographic analysis of the dye species
Reaction involved in this system can be explained as follows.
N
NN
Cl
X
NH
DyeNR'3
NR'3N
NN
X
NH
Dye
+
N
NN
O-Cell
X
NH
Dye
Cell-O
N
NN
OH
X
NH
Dye
A
B
OH
Fast
Slow
Conversion of commercial Procion Red PX-4B to its nicotinic acid derivative
N
ONH
NH
N
NNSO3H
SO3H SO3H
Cl
NH
CH3
Procion Red PX- 4B
N
CO2
N
ONH
NH
N
NNSO3H
SO3H SO3H
NH
CH3
+
Nicotinc derivative of Procion Red PX - 4B
N
COOH
pH 6.0 - 6.580 - 85oC
Comparison of the fixation yield (and dye species) of Procion Red PX-4B and its synthesised nicotinic acid derivative
Thus, it can be concluded thatrapid hydrolysis of the in-situ formed quaternary salt was one of the reasons for the reduction in colour yield.
Comparison of colour yields at lower pH (7.0)
Conclusion
Addition of nicotinic acid to the pad liquor of the one-pass continuous dyeing process, as a catalyst, even though it resulted in ‘in-situ’ formation of the (more active) 3-carboxy pyridinium-s-triazinyl derivative, failed to give an improvement in colour yield of selected Procion PX and Levafix CA reactive dyes at pH 9.0 on unmercerised cotton.
…….THANKS…….