Scouring

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Scouring

  1. 1. SCOURING TREATMENT OF COTTON WITH ALKALINE SOLUTION <ul><li>PURPOSE </li></ul><ul><li>REMOVE NATURAL IMPURITIES : FATS AND WAXES, </li></ul><ul><li>PECTIC SUBSTANCES, PROTINES </li></ul><ul><li>REMOVE ADDED IMPURITY : OIL STAINS </li></ul><ul><li>SEED COAT FRAGMENTS </li></ul><ul><li>IMPROVE WATER ABSORBENCY FOR UNIFORM DYING, </li></ul><ul><li>PRINTING AND FINISHING . </li></ul>
  2. 2. SCOURING AGENTS CHOICE DEPENDS ON NATURE OF FIBRE AND NATURE OF IMPURITIES TO BE REMOVED <ul><li>ALKALIES </li></ul><ul><li>NaOH, Na 2 CO3, Na 2 Sio3, Na 3 PO4 etc </li></ul><ul><li>SURFACTANTS </li></ul><ul><li>ANIONIC, NONIONIC, CATIONIC </li></ul><ul><li>EMULSIONS </li></ul><ul><li>SOLVENT, WATER, EMULSIFYING AGENTS </li></ul><ul><li>SOLVENTS </li></ul><ul><li>TRICHLORO OR PERCHLORO ETHYLENE </li></ul>
  3. 3. MECHANISM <ul><li>FATS AND WAXES </li></ul><ul><li>SAFONIFICATION OF FATS AND WAXES BY ALKALI AND SURFACE ACTIVE AGENTS. </li></ul><ul><li>IN EXTREME CASES SOLVENTS USED </li></ul><ul><li>PECTINS </li></ul><ul><li>SOLUBLIZED AS - COONa </li></ul>
  4. 4. MECHANISM <ul><li>PROTEINS </li></ul><ul><li>HYDROLYSIS INTO SIMPLE WATER SOLUBLE AMINO ACIDS </li></ul><ul><li>MINERAL MATTER </li></ul><ul><li>REMOVE DURING SOURING </li></ul>
  5. 5. <ul><li>CAUSTIC SODA BOIL </li></ul><ul><li>LIME – SODA BOIL ( PRESENTLY NOT USED ) </li></ul><ul><li>SODA ASH BOIL </li></ul><ul><li>SODA ASH - CAUSTIC SODA BOIL </li></ul><ul><li>CAUSTIC SODA BOIL IS MOST COMMON </li></ul>SCOURING OPERATION
  6. 6. <ul><li>CASTIC SODA BOIL </li></ul><ul><li>BOILING WITH 3-6% NAOH, 6-8 HOURS , </li></ul><ul><li>130 OC, M : L RATIO 3 : 1 </li></ul>PROCESSES
  7. 7. PROCESSES <ul><li>SODA ASH BOIL </li></ul><ul><li>USED FABRIC WOVEN WITH COLOURED YARNS (STRIPES, CHECKS ETC) </li></ul><ul><li>FOR DESIGN EFFECTS </li></ul><ul><li>SODA ASH - CASTIC SODA BOIL </li></ul><ul><li>COMBINATION OF 1 PART SODA ASH AND 2 PART CAUSTIC SODA MINIMIZES FABRIC DEGRADATION </li></ul>
  8. 8. <ul><li>AFTER TREATMENTS </li></ul><ul><li>HOT WATER WASH </li></ul><ul><li>NEUTRALIZE WITH 2 – 3G/L HCL OR H 2 SO 4 </li></ul><ul><li>WASH WITH COLD WATER TO NEUTRAL PH. </li></ul>
  9. 9. AUXILIARY CHEMICALS <ul><li>SURFACTANTS / DETERGENT </li></ul><ul><li>ANIONIC OR NON IONIC PRODUCT ARE USED </li></ul><ul><li>ASSIST IN THE EMULSIFICATION OF WAXES </li></ul><ul><li>KEEP IMPURITIES IN THE SUSPENDED FORM </li></ul><ul><li>EASY REMOVAL OF IMPURITIES DURING SUBSEQUENT WASHING </li></ul>
  10. 10. AUXILIARY CHEMICALS <ul><li>SEQUESTERING AGENTS </li></ul><ul><li>ALSO KNOWN AS METAL CHELATING AGENTS </li></ul><ul><li>BIND HEAVY METALS LIKE CU, FE, CA, MG PRESENT IN WATER </li></ul><ul><li>MINIMIZES FABRIC DEGRADATION </li></ul><ul><li>MOST COMMON AGENT IS EDTA ( ETHYLENE DIAMINE TETRA ACETIC ACID ) </li></ul><ul><li>SELECT PRODUCT WHICH STABLE UNDER TREATMENT CONDITIONS </li></ul>
  11. 11. AUXILIARY CHEMICALS <ul><li>MILD REDUCING AGENT </li></ul><ul><li>LIKE NAHSO 3 PRESVENT THE FORMATION OF OXYCELLULOSE DURING ALKALINE BOIL </li></ul>
  12. 12. AUXILIARY CHEMICALS <ul><li>MILD OXIDIZING AGENT </li></ul><ul><li>USED IN CASE OF COLOURED THREAD EFFECT </li></ul><ul><li>PROTECT THE BLEEDING OF DYE FROM FABRIC DUE TO REDUCING ACTION OF CHO GROUPS </li></ul><ul><li>( ALDEHYDIC) OF CELLULOSE </li></ul><ul><li>PREVENT STAINING OF WHITE PROTINS </li></ul><ul><li>MAINTAIN BRIGHTNESS OF SHADE </li></ul>
  13. 13. INDUSTRIAL PRACTICES <ul><li>SCOURING OF COTTON CAN BE CARRIED OUT IN </li></ul><ul><li>ROPE </li></ul><ul><li>OPEN WIDTH FORM </li></ul><ul><li>PROCESSES </li></ul><ul><li>BATCH WISE </li></ul><ul><li>CONTINUOUS </li></ul><ul><li>SEMI CONTINUOUS </li></ul>
  14. 14. INDUSTRIAL PRACTICES EQUIPMENT USED <ul><li>BATCH WISE OPERATION </li></ul><ul><li>KIER ( ROPE FORM ) </li></ul><ul><li>JIGGER (OPEN WIDTH ) </li></ul><ul><li>WINCH (ROPE FORM, PARTICULARLY FOR KNITS ) </li></ul><ul><li>JET DYING (ROPE FORM, PARTICULARLY FOR KNITS ) </li></ul><ul><li>CONTINUOUS </li></ul><ul><li>J – BOX ( ROPE FORM ) </li></ul><ul><li>VARIOUS PAD STEAM PROCESSES (OPEN WIDTH ) </li></ul>
  15. 15. INDUSTRIAL PRACTICES <ul><li>SEMI CONTINUOUS </li></ul><ul><li>PAD ROLL (OPEN WIDTH ) </li></ul><ul><li>AMONG THE ABOVE PROCESSES THE KIER BOILING OPERATION AND SCOURING IN J-BOX ARE MOST POPULAR. HOWEVER THE PRESENT TREND IS TO PROCESS THE FABRIC IN OPEN WIDTH FORM. THEREFORE THE PAD STEAM PROCESSES ARE GINNING IMPORTANCE . </li></ul>
  16. 16. INDUSTRIAL PRACTICES <ul><li>KIER BOILING </li></ul><ul><li>FABRIC STATIONARY-LIQUOR MOVING </li></ul><ul><li>CIRCULATION OF HOT ALKALINE LIQUOR THROUGH A BATCH OF FABRIC PILED IN IRON VESSEL KNOWN AS KIER </li></ul><ul><li>DESIZED CLOTH IS IMPREGNATED WITH ALKALINE SOLUTION AND SQUEEZED BEFORE PILING INTO KIER </li></ul><ul><li>THIS HELPS FOR UNIFORM TREATMENT OF FABRIC WITH ALKALI </li></ul>
  17. 17. INDUSTRIAL PRACTICES <ul><li>KIER </li></ul><ul><li>VERTICAL IRON VESSEL </li></ul><ul><li>CEMENTED FROM INSIDE TO PREVENT CORROSION AND IRON CONTAMINATION </li></ul><ul><li>CAPACITY 500 KG. TO 5 TONS </li></ul><ul><li>2 TON MOST COMMON </li></ul><ul><li>PROVIDED WITH FALLS BOTTUM </li></ul><ul><li>LID AT TOP </li></ul><ul><li>TEMPERATURE AND PRESSURE GAUGE </li></ul><ul><li>LIQUOR SPRAYER AT TOP </li></ul><ul><li>CONCERNED TO MULTITUBULOR HEATER TRROUGH LIGUOR CIRCULATION PUMP </li></ul>
  18. 18. INDUSTRIAL PRACTICES <ul><li>FABRIC PILING </li></ul><ul><li>MANUAL NOT COMMON </li></ul><ul><li>MECHANICAL MOST COMMON </li></ul><ul><li>UNIFORM PILING </li></ul><ul><li>SCOURING LIQUOR CAN BE FED ALONG WITH FOR FABRIC SATURATION </li></ul>
  19. 19. INDUSTRIAL PRACTICES <ul><li>OPERATION </li></ul><ul><li>AFTER CLOTH PILING, KEEP HEAVY WEIGHTS ON TOP LAYERS TO PREVENT FABRIC LAYERS TO PREVENT FABRIC LAYER DISPLACEMENT DUE TO LIQUOR CIRCULATION </li></ul><ul><li>INTRODUCE SCOURING LIQUOR FROM BOTTOM TO SWEEP OFF AIR FROM KIER </li></ul><ul><li>CLOSE THE LID , BUT KEEP THE VALVE OPEN </li></ul><ul><li>HEAT THE LIQUOR AND CIRCULATE TROUGH THE FABRIC LOAD </li></ul><ul><li>THIS WOULD ENSURE COMPLETE REMOVAL OF AIR </li></ul>
  20. 20. INDUSTRIAL PRACTICES <ul><li>OPERATION </li></ul><ul><li>CLOSE THE VALVE TO BUILD UP THE PRESSURE </li></ul><ul><li>CIRCULATE THE HEATED LIQUOR UNDER PRESSURE ( 30 LB/IN 2 , 130 O C) FOR 4-8 HOURS </li></ul><ul><li>SLOWLY RELEASE THE PRESSURE </li></ul><ul><li>INITIALLY DRAIN FROM TOP PIPE TO REMOVE SCUM FORMED DURING BOILING OPERATION </li></ul><ul><li>THEN DRAIN FROM BOTTOM </li></ul><ul><li>WASHING AND NEUTRALIZATION CAN BE CARRIED OUT IN KIER OR SEPARATELY </li></ul>
  21. 21. SCOURING IN J-BOX TYPES OF J - BOX DU PONT : FABRIC PRE – HEATING BECCO : NO FABRIC PRE – HEATING
  22. 22. INDUSTRIAL PRACTICES <ul><li>SCOURING IN J-BOX </li></ul><ul><li>PROCESSING IN ROPE FORM </li></ul><ul><li>STORAGE AND HEATING OF ALKALI SATURATED FABRIC IN A STAINLESS STILL VESSEL OF SHAPE LETTER J </li></ul><ul><li>TOTALLY INSULATED IN RETAIN FABRIC TEMPERATURE DURING STORAGE </li></ul><ul><li>DEPENDING ON SPEED, THE STORAGE TIME CAN BE ADJUSTED </li></ul><ul><li>AFTER INITIAL FILLING MAINTAIN CONSTANT STORAGE TIME BY KEEPING SAME IN-LET AND OUT-LET SPEED </li></ul>
  23. 23. INDUSTRIAL PRACTICES SCOURING IN J-BOX <ul><li>OPERATION </li></ul><ul><li>SATURATION OF FABRIC WITH 40 G/L NAOH, 10 G/L NA 2 CO 3 , 10 G/LNA 2 SIO 3 AND 5 G/L WETTING AGENT </li></ul><ul><li>SQUEEZING THE EXCESS LIQUOR BY PADDING </li></ul><ul><li>PRE HEATING THE FABRIC TO 100 O C </li></ul><ul><li>PILING INTO J-BOX </li></ul><ul><li>HEATING OF PILED FABRIC BY STEAM INJUNCTION TO MAINTAIN FABRIC TEMPERATURE 100 O C </li></ul><ul><li>STORAGE TIME 1.5 TO 2 HOURS </li></ul><ul><li>TAKING OUT THE FABRIC </li></ul><ul><li>HOT AND COLD WATER WASHING IN ROPE WASHER </li></ul>
  24. 24. CONTINUOUS SCORING

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