Dyeing of polester cotton blends


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Dyeing of polester cotton blends

  1. 1. Dyeing of polester/cotton blends R.B.Chavan Department of Textile Technology Indian Institute of Technology Hauz-Khas, new Delhi
  2. 2. Dyeing methods <ul><li>Batchwise methods </li></ul><ul><li>Semi continous </li></ul><ul><li>Continuous methods </li></ul><ul><li>Batch wise equipments </li></ul><ul><li>HTHP beam dyeing </li></ul><ul><li>Jet dyeing </li></ul><ul><li>High temp. winch or jigger </li></ul><ul><li>Semi-continuous </li></ul><ul><li>Pad-develop (Disperse/vat) </li></ul><ul><li>Continuous </li></ul><ul><li>Thermosol (Disperse/Reactive) </li></ul>
  3. 3. Dye classes <ul><li>Two dye class systems </li></ul><ul><li>Polyester </li></ul><ul><li>Only disperse dye class </li></ul><ul><li>Cotton </li></ul><ul><li>While dyeing cotton preference is given to dye classes which produce shades with good fastness </li></ul><ul><li>Most important </li></ul><ul><li>Reactive </li></ul><ul><li>Vat </li></ul><ul><li>Sulphur </li></ul><ul><li>Direct (Limited) </li></ul><ul><li>Single dye class systems </li></ul><ul><li>Solubilized vat </li></ul><ul><li>Pigment </li></ul><ul><li>Special disperse dyes </li></ul>
  4. 4. Dyeing methods <ul><li>Exhaust methods </li></ul><ul><li>Two bath dyeing process </li></ul><ul><li>Dyeing PET with disperse dyes </li></ul><ul><li>Subsequent dyeing cotton with vat, reactive, sulphur, direct dyes </li></ul><ul><li>One bath one step dyeing process </li></ul><ul><li>Disperse/Reactive </li></ul><ul><li>Disperse/Direct </li></ul><ul><li>Disperse/Vat </li></ul><ul><li>One bath two step </li></ul><ul><li>Disperse/Vat </li></ul>
  5. 5. Dyeing methods <ul><li>Semi continuous </li></ul><ul><li>Disperse/Reactive </li></ul><ul><li>Disperse/Vat </li></ul><ul><li>Continuous </li></ul><ul><li>Disperse/Reactive </li></ul><ul><li>Pigment </li></ul><ul><li>Solubilized vat </li></ul><ul><li>Special disperse dyes </li></ul><ul><li>Selection of process and dye combination depends on Economy, equipment available, batch size, depth of shade, brilliancy etc. </li></ul>
  6. 6. Two bath dyeing <ul><li>Involves additional labour and time </li></ul><ul><li>Produce shades with good fastness </li></ul><ul><li>Easy to control </li></ul><ul><li>Dyeing under ideal conditions </li></ul><ul><li>Steps </li></ul><ul><li>Dyeing PET with disperse dye </li></ul><ul><li>Reduction clear </li></ul><ul><li>Dyeing cotton with suitable dye class </li></ul><ul><li>When dyeing with vat dyes intermediate reduction clear not essential </li></ul><ul><li>In carrier dyeing two bath method is preferred </li></ul><ul><li>Stability of carrier emulsion is limited in presence of large amount of salt </li></ul>
  7. 7. One bath dyeing <ul><li>Disperse/Vat </li></ul><ul><li>Vat dyes must ultra dispers or micro fine quality </li></ul><ul><li>Must have good dispersion stability under dyeig cnditions </li></ul><ul><li>Typical dyeing recipe </li></ul><ul><li>X% Disperse dye </li></ul><ul><li>Y% Vat dye </li></ul><ul><li>0.5-1% Dispersing agent </li></ul><ul><li>0.5-1% wetting agent </li></ul><ul><li>pH 4-5 with acetic acid (30%) </li></ul><ul><li>Prepare the bath woith dispersing agent, wetting aent and acetic acid </li></ul><ul><li>Treat material for 10-15 min at 50-60 deg.C </li></ul><ul><li>Add well dispersed disperse and vat dyes </li></ul><ul><li>Dye for 10-15 min </li></ul><ul><li>Raise temp. 120-130 deg.C in 60-90 min </li></ul>
  8. 8. One bath dyeing <ul><li>Rate of temp. rise depends on </li></ul><ul><li>Depth of shade </li></ul><ul><li>Rate of liquor circulation </li></ul><ul><li>Low rate of heating for pale to medium shades </li></ul><ul><li>70-80% disperse dye exhausted during heating phase </li></ul><ul><li>Rapid rate of heating for heavy shades </li></ul><ul><li>Major part of disperse dye does not exhaust until bath has reached 120 deg.C </li></ul><ul><li>After PET component dyeing </li></ul><ul><li>Cool bath 80 deg.C </li></ul><ul><li>Dye cotton by additn hydrosulphite and caustic soda </li></ul><ul><li>Concentration depend on vat dye category (Iw, IN, IN Special </li></ul><ul><li>Manufactureres recommendation to be followed </li></ul><ul><li>In case of IW add 10-15 g/l glaubers salt </li></ul>
  9. 9. One bath dyeing <ul><li>Vat dyes level out well at 80 deg.C </li></ul><ul><li>Dye at this temp for 15 min </li></ul><ul><li>Cool bath to 60 deg.C </li></ul><ul><li>Continue dyeing for 30 min. for better exhaustion </li></ul><ul><li>Risnse with cold wate </li></ul><ul><li>Oxidize with </li></ul><ul><li>1-2 ml/l Hydrogen peroxide (35%) </li></ul><ul><li>0.5-1 g/l anionic detergent </li></ul><ul><li>pH 9 with acetic acid 1-2 g/l (Fabric is highly alkaline </li></ul><ul><li>Treatment 15 min at 50 deg.C </li></ul><ul><li>Rinse with cold water </li></ul><ul><li>Soap at 95 deg.C for 25 min using 2 g/l sLissapol D </li></ul><ul><li>Hot and cold rinse </li></ul>
  10. 10. One bath two step dyeing <ul><li>Method is used when selected vat dyes severely stain PET component during high temp dyeing. </li></ul><ul><li>No staining of PET when vat dyes applied in leuco state below 90deg.C </li></ul><ul><li>Modified one bath two step method produces better results than applyeing disperse vat dyes simultaneously. </li></ul><ul><li>Mehthod </li></ul><ul><li>Dye PET with disperse dyes under HTHP conditions </li></ul><ul><li>Cool bth to 80 deg.C </li></ul><ul><li>Add dispersed vat dye </li></ul><ul><li>Run for 10 min </li></ul><ul><li>Add required amount of caustic soda and hydrosulphite </li></ul><ul><li>Continue dyeing as usual </li></ul><ul><li>Oxidize </li></ul><ul><li>Soap </li></ul><ul><li>Wash </li></ul>
  11. 11. Disperse/Reactive dyes <ul><li>Alkali stable disperse dyes and high temp stable (H-E) reactive dyes are used </li></ul><ul><li>dye at boil for required lenth of time </li></ul><ul><li>Cool the bath to 70-80 deg.C Add alkali for reactive dye fixation </li></ul><ul><li>Disperse dyes used should be stable to alkali. </li></ul><ul><li>Conventional reactive dyes are not stable to high temp. </li></ul><ul><li>Not suitable for one bath dyeing </li></ul>
  12. 12. Continuous dyeing Disperse/vat dyes <ul><li>Sequence of operaions </li></ul><ul><li>Padding with disperse/vat dyes </li></ul><ul><li>Intermediate drying </li></ul><ul><li>Thermosol </li></ul><ul><li>Vatting for vat dye fixation </li></ul>
  13. 13. <ul><li>pad-dry-thermosol-cool </li></ul><ul><li>Chemical pad-steam-Oxidize-wash-soap-wash </li></ul>