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DYE CONSUMPTION (TONNE)

DYE CONSUMPTION (TONNE). WORD FIBRE CONSUMPTION. CONSUMPTION (1000 TONNE). NH 2. NH 2. Na 2 SO 3. Na 2 SO 3. N . N . N. N. DYEING OF COTTON WITH DIRECT DYES. TYPICAL DYE STRUCTURE CONGO RED . DIRECT DYES. FEATURES PRESENCE OF SULPHONIC ACID GROUPS WATER SOLUBLE

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DYE CONSUMPTION (TONNE)

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  1. DYE CONSUMPTION (TONNE)

  2. WORD FIBRE CONSUMPTION CONSUMPTION (1000 TONNE)

  3. NH2 NH2 Na2SO3 Na2SO3 N N N N DYEING OF COTTON WITH DIRECT DYES • TYPICAL DYE STRUCTURE CONGO RED

  4. DIRECT DYES FEATURES • PRESENCE OF SULPHONIC ACID GROUPS • WATER SOLUBLE • ANIONIC IN NATURE • SUBSTANTIVITY/AFFINITY TO COTTON • APPLIED FROM AQUEOUS DYEBATH CONTAINING ELECTROLYTE • SIMPLE DYEING OPERATION • LOW WASH FASTNESS • WASH FASTNESS IMPROVED TO SOME EXTENT AFTER TREATMENT WITH CATIONIC DYE FIXING AGENT • WASH FASTNESS STILL NOT ADEQUATE COMPARED TO OTHER DYE CLASSES SUCH AS REACTIVE DYES

  5. DIRECT DYES USES • USED FOR DYEING OF LOW PRICED COTTON OR VISCOSE FABRIC, CUTAIN, FURNISHING OR CARPETS WITH GOOD LIGHT FASTNESS AND MODERATE WASH FASTNESS • CHEAP COTTON DRESSING GOWNS AND BED SPREADS WHICH ARE NOT WASHED REGULARLY • DUE TO LOW WASH FASTNESS, LIMITED USE. • BEING REPLACED TO GREAT EXTENT WITH REACTIVE DYES WHICH HAVE BETTER WASH FASTNESS AND PRODUCE BRIGHT SHADES.

  6. CLASSIFICATION • CLASSIFIED ACCORDING TO DYEING BEHAVIOUR CLASS A SELF LEVELLING • DYES WITH GOOD MIGRATION OR LEVELLING PROPERTIES i.e. DYES WHICH PRODUCE UNIFORM SHADE. NOT SENSITIVE TO DYEING CONDITIONS. CLASS B SALT CONTROLLABLE • UNIFORM SHADE PRODUCD ON CONTROLLED ADDITION OF SALT DURING DYEING CLASS C TEMPERATURE CONTROLLABLE • UNIFORM SHADE PRODUCED ON CAREFUL CONTROL OF DYEING TEMPERATURE AND SALT ADDITION

  7. EFFECT OF VARIOUS PARAMETERS ON DYEING TEMPERATURE • RATE OF DYEING AND PENETRATION INCREASES TEMPERATURE. DYES BEING HIGH MOLECULAR WEIGHT DYEING CARRIED OUT AT BOIL FOR GOOD PENETRATION. DYEING TIME • PRODUCTION OF LEVEL AND WELL PENETRATED DYEING IS FAVOURED BY INCREASED DYEING TIME. HOWEVER, PROLONGED BOILING CAUSES DECOMPOSITION OF MANY DIRECT DYES. THE DYEING TIME IS USUALLY 1 hr. AT BOIL LIQUOR RATIO • DYEBATH EXHAUSTION IS USUALLY DECREASED WITH INCREASE IN M:L RATIO. HOWEVER, UNIFORMITY OF DYEING IS IMPROVED.

  8. EFFECT OF VARIOUS PARAMETERS ON DYEING ELECTROLYTE • ELECTROLYTE IS ESSENTIAL FOR DYEING WITH DIRECT DYES • COMMON ELECTROLYTE USED COMMON SALT (NaCl) OR GLAUBER’S SALT (Na2SO4) • CONCENTRATION OF ELECTROLYTE IS GOVERNED • DYE CONCENTRATION: LESS SALT FOR LOW DYE CONCENTRATION • No OF SULPHONIC ACID GROUPS IN DYE MOLECULE: HIGH SALT WITH MORE No. OF SULPHONIC ACID GROUPS

  9. ROLE OF ELECTROLYTE • COTTON IN WATER : NEGATIVE SURFACE POTENTIAL • ANIONIC DYES DISSOLVED IN WATER : NEGATIVE CHARGE DUE TO IONOIZATION OF WATER SOLUBILIZING SO3Na GROUPS • DUE TO SIMILAR CHARGES: REPULSION BETWEEN DYE AND FIBRE SURFACE • FOR THE DYE TO GO ON FIBRE: NECESSARY TO REDUCE –Ve CHARGE OF FIBRE • ACHIEVED BY ADDITION OF ELECTROLYTE • ELECTROLYTE DISSOCIATE IN WATER, RELEASE +Ve CHARGE Na+ • Na+ ACCUMULATE AT THE –Ve CHARGED FIBRE SURFACE • NEUTRALIZE –Ve SURFACE POTENTIAL OF FIBRE • FACILITATE –Ve DYE MOLECULE ATTRACTION/ADSORPTION ON FIBRE

  10. BATCHWISE DYEING OF COTTON DYE DISSOLUTION • USE SOFT WATER FOR DYE DISSOLUTION AND DYEING. PASTE WITH COLD WATER. ADD SUFFICIENT QUANTITY OF BOILING WATER. STIRR. FILTR TO REMOVE ANY INSOLUBLE DYE PARTCLES • ADDITION OF 0.5-1 g/l WETTING AGENT HELPS TO WET OUT THE FIBRE DURING DYEING. GENERAL DYEING PROCEDURE CLASS A DYES • THE DISSOLVED DYE IS ADDED TO DYEING MACHINE • MAKE TO TOTAL VOLUME ACCORDING TO M:L RATIO • IF DYE IS SENSITIVE TO HARDNESS OF WATER, ADD 1-2 g/l SODIUM HEXAMETA PHOSPHATE OR SODA ASH • ADD SODIUM CHLORIDE, FOR PALE SHADE 5% OWM, MEDIUM SHADE 10%OWM AND HEAVY SHADE 20% OWM. • ENTER THE FABRIC AT 40-500C • RAISE THE TEMPERATURE TO BOIL IN 30-40 MIN. • CONTINUE DYEING AT BOIL FOR 30-45 MIN • RINSE WITH COLD WATER • AFTER TREAT WITH CATIONIC DYE FIXING AGENT. • DRY WITHOUT RINSING.

  11. CLASS B DYES SALT SENSITIVE DYES • ADD SALT IN INSTALMENTS DURING RAISING THE TEMP. TO BOIL • IF DESIRED SALT ADDITION MAY BE CONTINUED AFTER THE DYEBATH HAS REACHED TO BOIL. • ADDITION OF DISSOLVED SALT BY DRIP FEED METHOD IS PREFERRED

  12. CLASS C DYES TEMPERATURE SENSITIVE DYES • LOW ELECTROLYTE CONC. ADDED AT THE START • RAISE TEMP TO BOIL AT VERY LOW RATE • DYEING CONTINUED AT BOIL FOR 45-60 MIN. • SALT ADDITION SHOULD BE DONE IN INSTALMENTS AT BOIL. COMPOUND SHADES • PRODUCED BY USING TWO OR THREE DYES TAKEN TOGETHER • TAKE MIX DYES BELONGING TO THE SAME CLASS • DYES IN MIXTURE SHOULD HAVE SIMILAR RATE OF EXHAUSTION • DYE MANUFACTURER SHADE CARD GIVES INFORMATION ON DYE CLASS AND DYEING CONDITIONS • FOLLOW THE INSTRUCTIONS CAREFULLY AND FAITHFLLY.

  13. AFTER TREATMENT • INADEQUATE WASH AND PERSPIRATION FASTNESS OF DIRECT DYES • CAN BE IMPROVED BY AFTERTREATMENT AFTER DYEING • DIAZOTIZATION AND DEVELOPMENT • COPPER SULPHATE AND POTASSIUM DICHROMATE TREATMENT • FORMALDEHYDE TREATMENT • CATIONIC DYE FIXING AGENT: MOST POPULAR • FORMS COMPLEX WITH ANIONIC DYE. DECREASE IN DYE SOLUBILITY • TRETMENT CARRIED OUT USING 1-3%OWM CATIONIC AGENT AT 600C FOR 30 MIN AT pH 5 WITH ACETIC ACID. • NO RISING AFTER TREATMENT

  14. CATIONIC DYE FIXING AGENT

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