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Dyeing of polyester

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Dyeing of polyester

  1. 1. DYEING OF POLYESTER <ul><li>PET FIBRE IS HYDROPHOBIC AND CHARACTERIZED BY COMPACT PHYSICL STRUCTURE </li></ul><ul><li>ABSENCE OF DYE SITES </li></ul><ul><li>WATER SOLUBLE DYES ARE NOT SUITABLE </li></ul><ul><li>DYES OF LOW MOLECULAR WEIGHT MUST BE USED </li></ul><ul><li>ONLY DISPERSE DYE CLASS IS SUITABLE </li></ul><ul><li> </li></ul>
  2. 2. DYEING PRINCIPLE <ul><li>THERMAL EFFECTS </li></ul><ul><li>POLYMERIC CHAINS OF POLYESTER ARE CLOSELY PACKED AND HELD TOGETHER BY STRONG FORCES </li></ul><ul><li>FOR PENETRATION DYE MOLECULE MUST OVERCOME THESE FORCES </li></ul><ul><li>DYE MOLECULE CAN PENETRATE ONLY WHEN IT FINDS SPACE (VOID) IN THE COMPACT POLYMERIC STRUCTURE </li></ul><ul><li>SUCH VOIDS ARE FORMED DUE TO THERMAL MOBILITY OF POLYMERIC CHAINS ON APPLICATION OF HEAT </li></ul><ul><li>HIGHER THE TEMP., GREATER IS THERMAL MOBILITY AND GREATER THE CHANCES OF VOID FORMATION AND DYE PENETRATION </li></ul><ul><li>THE METHOD IS KNOWN AS HIGH TEMPERATURE DYEING </li></ul><ul><li>SWELLING AGENTS </li></ul><ul><li>CERTAIN COMPOUNDS KNOWN AS CARRIER PUSH THE POLYMERIC CHAINS APART (SWELLING) ALLOWING DYE TO PENETRATE INSIDE THE FIBRE. </li></ul><ul><li>THE METHOD IS KNOWN AS CARRIER DYEING </li></ul>
  3. 3. DYEING METHODS <ul><li>BATCH DYEING </li></ul><ul><li>DYEING AT BOIL WITHOUT CARRIER </li></ul><ul><li>CARRIER DYEING (DYEING AT BOIL USING CARRIER </li></ul><ul><li>HTHP DYEING (DYEING AT HIGH TEMPERATURE AND HIGH PRESSURE) </li></ul><ul><li>CONTINUOUS DYEING </li></ul><ul><li>THERMOSOL DYEING </li></ul>
  4. 4. DYEING WITHOUT CARRIER DYEING <ul><li>MACHINE: CLOSED JIGGER </li></ul><ul><li>METHOD </li></ul><ul><li>DYE IS DISPERSED IN WATER USING SUITABLE DISPERSING AGENT </li></ul><ul><li>START DYEING AT 50 0 C </li></ul><ul><li>RAISE TEMP. SLOWLY TO BOIL </li></ul><ul><li>CARRY OUT DYEING AT BOIL FOR 2 hrs. </li></ul><ul><li>SUITABLE ONLY FOR PALE SHADES </li></ul><ul><li>CHOICE OF DISPERSE DYE </li></ul><ul><li>LOW MOLECULAR WEIGHT DISPERSE DYES </li></ul><ul><li>HOWEVER FASTNESS TO HEAT (DOMESTIC IRON) IS LOW. </li></ul><ul><li>USED FOR DYEING THOSE MATERIALS NOT OFTEN SUBJECTED TO IRONING (CURTAIN FBRIC) </li></ul>
  5. 5. CARRIER DYEING
  6. 6. MECHANISM OF CARRIER <ul><li>CARRIER: COMPUNDS WHICH CARRY THE DYE INSIDE POLYESTER </li></ul><ul><li>COMLEX FORMATION </li></ul><ul><li>SUPPOSED TO FORM COMPLEX WITH DYE </li></ul><ul><li>COMPLEX DIFFUSE FASTER THAN THAN INSIDE THE FIBRE </li></ul><ul><li>UNLIKELY MECHANISM </li></ul><ul><li>DYE-CARRIER COMLEX IS LARGER THAN DISPERSE DYE </li></ul><ul><li>CARRIER ABSORPTION BY FIBRE </li></ul><ul><li>CARRIER IS ABSORBED BY FIBRE </li></ul><ul><li>FORMS THIN FILM ON FIBRE SURFACE </li></ul><ul><li>DYE DISSOLVES IN THE CARRIER FILM </li></ul><ul><li>DIFFUSES INSIDE THE FIBRE </li></ul><ul><li>SWELLING </li></ul><ul><li>CARRIER INTERACTS WITH FIBRE </li></ul><ul><li>PUSHSES POLYMER CHAIN APART (FIBRE SWELLING) </li></ul><ul><li>DYE PENETRATION IN SWOLLEN FIBRE </li></ul>
  7. 7. TYPES OF CARRIERS
  8. 8. CARRIERS <ul><li>CARRIERS OF POOR WATER SOLUBILITY ARE MORE EFFECTIVE THAN WATER SOLUBLE SOD. SALTS </li></ul><ul><li>THE CARRIER MUST BE FINELY DISPERSED OR EMULSIFIED TO AVOID SPECKY DYEING </li></ul><ul><li>SOME OF THE COMMERCIAL CARRIERS CONTAIN DISPERSING OR EMULSIFYING AGENTS </li></ul><ul><li>MANY CARRIERS ARE LIQUID AT ROOM TEMP. </li></ul><ul><li>SOME MELT AT DYEING TEMP </li></ul><ul><li>SOME ARE VOLATILE AT DYEING TEMP., CONDENSE ON COOLER PART OF MACHINE </li></ul><ul><li>FALL ON FABRIC IN THE FORM OF DROPS, GIVING DARKER SPOTS </li></ul><ul><li>MOST OF THE CARRIERS ARE TOXIC </li></ul><ul><li>PRECAUTION DURING HANDLING AND USE. </li></ul><ul><li>CONCENTRATION USED 5-20 g/l DEPENDING ON DEPTH OF SHADE </li></ul>
  9. 9. DYEING <ul><li>THE CARRIER IS DISPERSED (SOLID) OR EMULSIFIED (LIQUID) IN WATER </li></ul><ul><li>ADDED TO THE DYE BATH CONTAINGING DYE AND DISPERSING AGENT </li></ul><ul><li>START DYEING AT 50 0 C </li></ul><ul><li>RAISE TEMP. TO BOIL </li></ul><ul><li>CARRY DYEING AT BOIL FOR 2 hrs. </li></ul><ul><li>CLOSED JIGGER OR JET DYEING MACHINE MOST SUITABLE. </li></ul><ul><li>THOROUGH WASHING IN USING SODA ASH AND ANIONIC DETERGENT AT 60-70 0 C IS ESSENTIAL TO REMOVE CARRIER COMPLETELY FROM DYED FABRIC </li></ul><ul><li>RESIDUAL CARRIER SEVERLY AFFECTS LIGHT FASTNESS OF DYE. </li></ul>
  10. 10. HTHP DYEING <ul><li>MOST POPULAR METHOD OF DYEING ON COMMERCIAL SCALE </li></ul><ul><li>MACHINES USED ARE </li></ul><ul><li>BEAM DYEING MACHINE </li></ul><ul><li>JET DYEING MACHINE </li></ul><ul><li>DYEING TEMP. 120-130 0 C, PRESSURE 25-30lbs/sq in, TIME 1 hrs </li></ul><ul><li>ADVANTAGES </li></ul><ul><li>CARRIER NOT REQUIRED </li></ul><ul><li>DYEING TIME LESS THAN CARRIER DYEING, DUE RAPID DYE PENETRATION AT HIGH TEMP. </li></ul><ul><li>GOOD FASTNESS TO LIGHT AND WASH DUE TO SUPERIOR DYE PENETRATION AND ABSENCE OF CARRIER RESIDUES </li></ul><ul><li>GOOD DYE EXHAUSTION </li></ul><ul><li>PALE TO DEEP SHADES POSSIBLE </li></ul><ul><li>UNIFORM DYEING </li></ul>
  11. 11. DYEING <ul><li>DYEBATH </li></ul><ul><li>DISPERSE DYE X% </li></ul><ul><li>ACETIC ACID/CITRIC ACID 1g/l OR </li></ul><ul><li>AMM. SULPHATE 0.5 g/l </li></ul><ul><li>DISPERSING AGENT 1-2 g/l </li></ul><ul><li>START DYEING AT 50 0 C </li></ul><ul><li>RAISE TEMP. SLOWLY TO 120-130 0 C </li></ul><ul><li>DYE FOR 1 hr. </li></ul><ul><li>RINSE WITH COLD WATER, SOAP AT 60-70 0 C, RISNSE, DRY </li></ul><ul><li>REDUCTION CLEAR </li></ul><ul><li>IN CASE OF HEAVY SHADES, NECESSARY TO REMOVE SURFACE DYE FOR BEST FASTNESS PROPERTIES </li></ul><ul><li>ACHIEVED BY TREATMENT WITH 2g/L Na2S2O4 AND 2 g/l NaOH AT 60 0 C FOR 15 min. FOLLOWED BY SOAPING. </li></ul>
  12. 12. CONTINUOUS DYEING OF POLYESTER <ul><li> THERMOSOL DYEING </li></ul><ul><li>PAD-DRY-THERMOSOL AT 190-220 0 C FOR 30-60 sec. </li></ul><ul><li>PROBLEMS </li></ul><ul><li>LIQUOR PICK UP DURING PADDING </li></ul><ul><li>COMPARED TO NATURAL FIBRE, POLYESTER HAS LOW WATER RETENTION </li></ul><ul><li>VERY LOW DYE LIQUOR LEFT ON FABRIC AFTER PADDING </li></ul><ul><li>SOLUTION </li></ul><ul><li>INCREASE THE VISCOSITY OF PAD LIQUOR USING SUITABLE THICKNER </li></ul><ul><li>THICKENER ALSO MINIMIZES THE DYE MIGRATIN DURING DRYING. GIVE UNIFORM DYEING </li></ul><ul><li>CHOICE OF THICKENER </li></ul><ul><li>LOW SOLID CONTENT </li></ul><ul><li>SHOULD NOT AFFECT DISPERSION STABILITY OF DYE </li></ul><ul><li>SHOULD NOT HINDER DYE DIFFUSION </li></ul><ul><li>EASILY WASHED OUT </li></ul><ul><li>CONCENTRATION USED 5-10 g/l </li></ul><ul><li>SODIUM ALGINATE MOST SUITBLE </li></ul>
  13. 13. RATE OF DIFFUSION <ul><li>RATE OF DIFFUSION OF A DISPERSE DYE </li></ul><ul><li> FIBRE Temp. 0 C RELATIVE DIFFUSION RATE </li></ul><ul><li>POLYESTER 85 1 </li></ul><ul><li>POLYESTER 100 48 </li></ul><ul><li>ACETATE 85 460 </li></ul><ul><li>NYLON 85 680 </li></ul><ul><li>DYE DIFFUSION IN POLYESTER IS ACCELERATED USING HIGH TEMP. 190-220 0 C, FOR 30-60 sec. </li></ul>
  14. 14. DYEING METHOD <ul><li>PADDING </li></ul><ul><li>DYE X g/l </li></ul><ul><li>DISPERSING AGENT 2 g/l </li></ul><ul><li>SOD. ALGINATE THICKENER 5-10 g/l </li></ul><ul><li>CITRIC ACID TO GET pH 4-5 </li></ul><ul><li>TWO DIP, TWO NIP PADDING </li></ul><ul><li>DRYING </li></ul><ul><li>DRY IN STENTER AT 70-80 0 C </li></ul><ul><li>DYE FIXATION </li></ul><ul><li>190-220 0 C FOR 30-60 sec. USING STENTER </li></ul><ul><li>METHOD KNOWN AS THERMOSOL </li></ul><ul><li>AFTER TREATMENT </li></ul><ul><li>COLD RINSE-HOT RINSE-SOAP AT 60-70 0 C-COLD RINSE </li></ul><ul><li>OPEN SOAPER IS USED </li></ul>
  15. 15. MECHANISM OF DYE FIXATION <ul><li>NERST DISTRIBUTION (SOLID SOLUTION THEORY) </li></ul><ul><li>DYE DISSOLUTION INSIDE THE FIBRE </li></ul><ul><li>FIBRE ACTING AS SOLVENT IN SOLID FORM FOR DYE DISSOLUTION </li></ul><ul><li>MECHANISM KNOWN AS SOLID SOLUTION </li></ul>

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