Lecture 7 pigment printing
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The document discusses the differences between dye and pigment printing, and the use of emulsion thickeners and synthetic thickeners in pigment printing. Emulsion thickeners contain kerosene oil which causes air pollution and safety issues, while synthetic thickeners do not have these problems but result in duller prints and a harsher fabric feel. The document also proposes a method for recovering kerosene vapors from dryers to reduce pollution.
Lecture 7 pigment printing
- 1. PIGMENT PRINTING DIFFERENCE BETWEEN DYE AND PIGMENT PIGMENT NO AFFINITY TO FIBRE INSOLUBLE IN WATER NEED BINDER FOR FIXATION ONTO FIBRE DYE AFFININTY TO FIBRE WATER SOLUBLE OR CAN BE MADE WATER SOLUBLE. EXCEPTION DISPERSE DYE HELD ON FIBRE DYE-FIBRE INTERACTIVE FORCES
- 2. BINDER IT IS PRE-POLYMER AVAILABLE IN THE FORM OF AQUESOUS EMULSION CHEMICAL NATURE COPOLYMER OF STYRENE-BUTYL ACRYLATE-N-METHYLOL ACRYL AMIDE
- 3. MECHANISM OF BINDING SEQUENCE PRINT > DRY > CURE DURING CURING: BINDER POLYMERISES AND FORMS A STRONG FILM BINDER FILM EMBEDES PIGMENT COLOUR AND ALSO STRONGLY ADHARES TO THE FIBRE
- 4. CHOICE OF THICKENER CONVENTIONAL THICKENER USED FOR DYE PRINTING ARE NOT SUITABLE THEY INTERACT WITH BINDER AND REDUCE ITS INTERATION WITH FIBRE. THUS AFFECTING THE FASTNESS PROPERTIES SUITABLE THICKENERS EMULSION THICKENER – ZERO SOLID CONTENT THICKENER SYNTHETIC THICKENER - VERY LOW SOLID CONTENT THICKENER
- 5. EMULSION THICKENER OBTAINED BY EMULSIFICATION OF TWO IMMISCIBLE LIQUIDS WITH THE HELP OF EMULSIFIER TWO TYPES OIL-IN-WATER EMULSION WATER-IN-OIL EMULSION COMMONLY USED IS OIL-IN-WATER
- 6. PREPARATION OF OIL-IN-WATER EMULSION BINDER 100 PARTS WATER 100-150 PARTS EMULSIFIER 20 PARTS UREA 20 PARTS CMC (4-6% PASTE) 10 PARTS KEROSENE OIL 750-800 PARTS MINERAL TURPENTINE OIL VERY SLOW ADDITION OF OIL CONTINUOUS HIGH SPEED STIRRING EMULSIFIER: REDUCE SURFACE ENERGY BETWEEN OIL AND WATER UREA: HYGROSCOPIC AGENT, MINIMIZE WATER EVAPORATION IN CONTINUOUS PHASE CMC: PROTECTIVE COLLOID
- 7. EMULSION THICKENER MERITS IDEAL FOR PIGMENT PRINTING DEMERITS INFLAMMABLE- FIRE HAZARDS AIR POLLUTION FABRIC SMELLS DUE TO RESIDUAL K.OIL OR MTO. NOT ACCEPTABLE IN EXPORT MARKET
- 8. KEROSENE CONSUMPTION IN INDIA FOR PIGMENT PRINTING Pigment printed cloth production 5231 million sq m Kerosene consumption 136 million litres Kerosene evaporation in atmosphere 122 million litres Effect Air pollution Wastage of kerosene
- 9. KEROSENE RECOVERY The kerosene vapors are explosive in nature above 0.7% of concentration, thus, for safety reasons, the machine drier exhaust is maintained within 0.5% kerosene vapor level. Therefore, the recovery of this diluted vapor is a very difficult task. BTRA METHOD Devised a method for recovery of kerosene vapours from the dryer by using water cooling system Claim 80% kerosene recovery Plant was installed at Dhanlaxmi fabrics Ltd Near Mumbai Present status not known
- 10. SYNTHETIC THICKENER CHEMICAL NATURE HIGH MOL.Wt. COPOLYMERS OF ACRYLIC OR METHACRYLIC ACID HAVE FREE –COOH GROUPS ON POLYMERIC CHAINS WHICH HAS ROLE IN VISCOSITY BUILD UP TRADE PRODUCTS: AQUEOUS EMULSION, ACID pH CONCENTRATION FOR PRINTABLE VISCOSIT 1-2%
- 11. MECHANISM OF THICKENING SYNTHETIC THICKENER IN ACID FORM WATER INSOLUBLE, LOW VISCOSITY, NON-IONIZED –COOH GROUPS SYNTHETIC THICKENER IN NEUTRIZED FORM WATER SOLUBLE, SWELLABLE, HIGH VISCOSITY IONIZED –COOH GROUPS
- 12. SYNTHETIC THICKENER MERITS NO AIR POLLUTION NO RISK OF FIRE AND EXPLOSION NO SPECIAL STORAGE REQUIREMENTS NO FABRIC SMELL DEMERITS ELECTRLYTE SENSITIVITY SLIGHTLY DULL PRINTS AND HARSH FABRIC FEEL LONGER DRYING TIME
- 13. PREPARATION OF THICKENER PASTE BINDER 100 PARTS WATER 80-890 PARTS SYNTH. THICKENER 10-20 PARTS LIQUOR AMMONIA TO pH 8
- 14. PRINT PASTE COMPOSITION PIGMENT COLOUR X PARTS THICKENER PASTE TO MAKE 1000 PARTS DIAMM. PHOSPHATE 10 PARTS MELAMINE FORMALDEHYDE 10 PARTS SEUENCE PRINT > DRY > CURE AT 140-150 0 C FOR 4-5 MIN. NO WASH
- 15. MERITS AND DEMERITS PRACTICALLY ALL TYPES OF FIBRES AND BLENDS CAN BE PRINTED PIGMENT COLOURS CAN BE READILY MIXED WITH EACH OTHER TO GET QUICK SHADE MATCHING NO AFTER TREATMENT SUCH AS WASHING, SOAPING REQUIRED DEMERITS HARSH FABRIC FEEL DUE TO BINDER FILM LOW RUBBING FASTNESS