Kaliakor Dye Managers Workshop

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Kaliakor Dye Managers Workshop

  1. 1. Reactive Dyes Dr Kelvin N Tapley Department of Colour Chemistry University of Leeds, Leeds, UK September 2003 Kaliakor Dye Managers Workshop
  2. 2. Outline <ul><li>History </li></ul><ul><li>General Features </li></ul><ul><li>Advantages & Disadvantages </li></ul><ul><li>Factors influencing performance </li></ul><ul><li>Common Types of Reactive Dyes </li></ul><ul><li>Reactions of Reactive Dyes </li></ul><ul><li>Application Methods </li></ul><ul><li>Summary </li></ul>
  3. 3. History <ul><li>Cyanuric chloride reaction with cotton and then amines </li></ul><ul><li>Remazol (vinyl sulphone) chemistry intorduced </li></ul><ul><li>1956 Rattee + Stephen (ICI) “first” reactive dyes </li></ul><ul><ul><li>chlorotriazines </li></ul></ul><ul><li>Various developments – including new chemical types </li></ul><ul><li>1980’s Mixed bifunctional dyes (esp. Sumitomo – Sumifix Supra dyes) </li></ul>
  4. 4. General Features of a Reactive Dye Molecule <ul><li>W = water solubilising group </li></ul><ul><li>D = chromophore </li></ul><ul><li>B = bridging group </li></ul><ul><li>RG = reactive group </li></ul><ul><li>X = leaving group </li></ul>
  5. 5. Advantages? <ul><li>Full Colour Gamut </li></ul><ul><li>Brilliant, bright colours </li></ul><ul><li>Colvalent fixation  high WashFastness (WF) </li></ul><ul><li>Varying reactivities </li></ul><ul><ul><li>Various temperatures </li></ul></ul><ul><li>including low energy (cold dyeing) </li></ul><ul><li>Various methods of application </li></ul><ul><li>Inexpensive to apply (but dyes expensive) </li></ul>
  6. 6. Disadvantages? <ul><li>Incomplete fixation (problem with hydrolysis) </li></ul><ul><li>Need for wash-off (for high WF) </li></ul><ul><li>Need for high concentrations of salt </li></ul><ul><ul><li>Affect natural balance of watercourses </li></ul></ul><ul><li>High pH </li></ul><ul><li>Some dyes are “AOX” – potentially harmful to the environment </li></ul>
  7. 7. <ul><li>Loss of colour  fading problems </li></ul><ul><li>Transfer of colorants to “adjacent” fabrics leads to staining problems </li></ul><ul><li>NB some of the WF tests have got tougher! </li></ul>The major issues Importance of Washing Fastness (WF)
  8. 8. Poor wash fastness Laundry washing
  9. 9. During the laundry process the fabric is subjected to some severe conditions and very often dye is “beaten” from the fabric. This results in dye entering the washing liquors. Once in the washing liquors 3 things can happen to the dye... 1. Re-adsorb onto original fibre 2. Adsorb to a different substrate 3. Remain in the wash liquor
  10. 10. affinity of dye for original fibre Degree of staining = + affinity of dye for adjacent fibre affinity for water (staying in solution) +
  11. 11. Factors that affect the dyeing of cotton with reactive dyes Dyebath (liquor ratio/flow) Cotton Method: eg.Temperature and duration of dyeing Auxiliaries Pre-treatment Reactive dye
  12. 12. Factors Influencing the Performance of Reactive Dyes <ul><li>Molecular structure of Dye </li></ul><ul><ul><li>Number of reactive groups </li></ul></ul><ul><ul><li>Chemical nature of reactive groups </li></ul></ul><ul><ul><li>Molecular mass (size) </li></ul></ul><ul><ul><li>Number of sulphonic acid groups </li></ul></ul><ul><ul><li>Ratio of sulphonic acid groups to aromatic carbons </li></ul></ul><ul><ul><ul><li>hydrophobic – hydrophilic balance </li></ul></ul></ul><ul><ul><li>Linear / planar structure (shape) </li></ul></ul><ul><ul><li>Other functional groups present </li></ul></ul><ul><ul><li>Realtive positions of functional groups (incl. reactive groups) </li></ul></ul><ul><li>Plus characteristics and quantity of impurities / additives </li></ul>
  13. 13. Factors Influencing the Performance of Reactive Dyes <ul><li>Material being dyed </li></ul><ul><ul><li>Chemical type (assume cellulosic) </li></ul></ul><ul><ul><li>(Macro) physical structure (yarn, fabric, garment) </li></ul></ul><ul><ul><li>(Micro) physical structure (crystallinity vs amorphous) </li></ul></ul><ul><ul><li>Material preparation or damage prior to coloration </li></ul></ul><ul><ul><ul><li>Exposure to physical, chemical and biological agents </li></ul></ul></ul>
  14. 14. Pre-treatment is crucial to a dyer if he wants to achieve right-first-time dyeings. After pre-treatment he can trust his fabric . It is easy to appreciate that what happens to the fabric before dyeing will affect dyeing itself ! Pre-treatment for cotton principally involves: Scouring and bleaching Pre-treatment
  15. 15. Exhaustion Time Scouring Essentially cleaning! removal of waxes, fatty acids etc. Definition of scour : To remove natural impurities, dirt or grease from (cloth or fibers) by means of a detergent. Scoured Unscoured
  16. 16. Factors Influencing the Performance of Reactive Dyes <ul><li>Application conditions </li></ul><ul><ul><li>Quality of the water employed </li></ul></ul><ul><ul><li>Temperature programme employed </li></ul></ul><ul><ul><li>pH programme employed (incl type + conc of alkali) </li></ul></ul><ul><ul><li>Electrolyte programme employed </li></ul></ul><ul><ul><li>Any other additives/chemicals present (eg. Auxiliaries) </li></ul></ul><ul><ul><li>Liquor to materials ratio (LR) </li></ul></ul><ul><ul><li>Chemical (incl Dye) addition programme employed </li></ul></ul><ul><ul><li>Agitation / liquor circulation method </li></ul></ul><ul><ul><li>Time – at each stage </li></ul></ul><ul><li>[Rinse/Wash/After treatment conditions are also important] </li></ul>
  17. 17. Factors Influencing the Performance of Reactive Dyes <ul><li>Application conditions – the “Human Factor” </li></ul><ul><ul><li>You may not be using an optimum method </li></ul></ul><ul><ul><li>Do you / your operatives actually do what you say you do? </li></ul></ul><ul><ul><li>Try to identify real / potential problem areas, for example: </li></ul></ul><ul><ul><ul><li>Volume of water used (LR). Why? </li></ul></ul></ul><ul><ul><ul><li>Housekeeping </li></ul></ul></ul><ul><ul><ul><li>Use of Chemicals (dyes, electrolyte, alkali, auxiliaries) </li></ul></ul></ul><ul><ul><ul><li>Temperature (including storing/dissolving dyes) </li></ul></ul></ul><ul><ul><ul><li>Time </li></ul></ul></ul>
  18. 18. Types of Reactive Dyes <ul><li>[Some examples!] </li></ul>
  19. 19. Vinyl sulphone dye (Remazol Brilliant Blue R, C.I. Reactive Blue 19) Sulphatoethyl sulphone dyes
  20. 20. Monochloro-s-triazine dye (Procion Red H-3B, C.I. Reactive Red 3) Monochloro- s -triazine dyes
  21. 21. Bis(monochloro-s-triazine) dye (Procion Red HE-3B, C.I. Reactive Red 120) Bis (monochloro- s -triazine) dyes
  22. 22. 2,4-difluoro-5-chloro-pyrimidine dye (Levafix Brilliant Red E 3BA, C.I. Reactive Red 147) 2,4-difluoro-5-chloro-pyrimidine dyes
  23. 23. Trichloro pyrimidine dye (Drimarene Red Z 2B, C.I. Reactive Red 17) 2,4,5-trichloro-pyrimidine dyes
  24. 24. General structure of Sumifix Supra dyes MCT-SES or MCT-VS [Reactron Supra F dyes are similar] Mixed Bifunctional reactive dyes eg.
  25. 25. Reactions of Reactive Dyes <ul><li>[Some examples!] </li></ul>
  26. 26. Nucleophilic addition The reactive group is usually the vinylsulphone group Sulphone (SO2) Vinyl (CH = CH2) Reactive group SO 2 - CH = CH 2
  27. 27. ß-elimination of ß-sulphatoethylsulphone to vinyl sulphone and reaction with cellulose . Nucleophilic addition
  28. 28. Nucleophilic substitution The reactive groups is usually a halogenated heterocyclic group e.g. a dichloro-s-triazine reactive group Reactive group N N N Cl Cl
  29. 29. Competing nucleophilic substitution reactions of s-triazine dyes Nucleophilic substitution
  30. 30. Separation of bis -Monochlorotriazinyl Reactive Dyes and Hydrolysates in Dyehouse Effluent by Capillary Zone Electrophoresis
  31. 31. Application Methods <ul><li>Continuous </li></ul><ul><ul><li>eg. Pad - Thermofix </li></ul></ul><ul><li>Semi-Continuous </li></ul><ul><ul><li>eg. Pad - Batch </li></ul></ul><ul><li>Batchwise Exhaustion * </li></ul><ul><ul><li>eg. Winch, Jet, Package and Beam Dyeing </li></ul></ul><ul><li>Printing </li></ul><ul><ul><li>eg. Print - Thermofix </li></ul></ul>
  32. 32. Typical dyeing conditions for a bifunctional monochlorotriazine dye
  33. 33. Typical dyeing conditions for a bifunctional dichlorotriazine dye
  34. 34. Typical dyeing conditions for a bifunctional sulphatoethyl sulphone dye
  35. 35. Summary <ul><li>Dominant dye class for cotton </li></ul><ul><li>Importance of nature and number of reactive groups (  covalent fixation) </li></ul><ul><li>Different types/chemistries </li></ul><ul><ul><li>many different application methods </li></ul></ul><ul><li>Problem of dye hydrolysis </li></ul><ul><li>Potential impact on environment </li></ul>
  36. 36. Acknowledgements Department of Colour Chemistry, University of Leeds DFID [email_address] Department of Colour Chemistry, University of Leeds, Leeds, LS2 9JT www.leeds.ac.uk/ccd
  37. 37. Questions ?

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