1. 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 Materials The University of Manchester, Manchester, UK Email: dr.arshadmehmood@yahoo.com

2.  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 CSS Colour synthesis solutions Ltd. is based at Hexagon Tower, Blackley, Manchester, UK www.coloursynthesissolutions.co.uk The main features of CSS’s business are as follows.

3.  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.

4.  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  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.

5. 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 X = usually a substituted arylamino group

6. PAD LIQUOR INCLUDES: oREACTIVE DYE y g/l oMIGRATION INHIBITOR 10-20 g/l oWETTING AGENT2-4 g/l oSEQUESTERING AGENT0-4 g/l oFIXATION ASSISTANT 15 g/l oALKALI (SODIUM BICARBONATE)2-10 g/l oPAD LIQUOR TEMPERATURE20-30oC oNICOTINIC 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

7. Investigation of the addition of nicotinic acid to the pad liquor of one-pass process. (PROCION PX DYES)

8. Investigation of the addition of nicotinic acid to the pad liquor of one-pass process. (LEVAFIX CA DYES)

9. 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

10. Investigation of the 1 st possible cause Fixation/Dye species Retention time (t R ) by HPLC (Determined by prepared standards) After 30secs Drying After 60secs Drying After 30secs Thermofixation After 60secs Thermofixation Fixation (%) 343038 Parent (MCT) dye (%) 4.9663613728 In-situ formed 3-carboxypyridinium triazine dye (%) 2.1920191512 Hydrolysed dye (%) 3.2814161822  Increase in dyeing time scale  Chromatographic analysis of the dye species

11. Reaction involved in this system can be explained as follows. Fast Slow

12. Conversion of commercial Procion Red PX-4B to its nicotinic acid derivative

13. Comparison of the fixation yield (and dye species) of Procion Red PX-4B and its synthesised nicotinic acid derivative  Thus, it can be concluded that rapid hydrolysis of the in-situ formed quaternary salt was one of the reasons for the reduction in colour yield.

14. Comparison of colour yields at lower pH (7.0)

15. 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.

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