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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. BINDER.
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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
BINDER • IT IS PRE-POLYMER AVAILABLE IN THE FORM OF AQUESOUS EMULSION CHEMICAL NATURE COPOLYMER OF STYRENE-BUTYL ACRYLATE-N-METHYLOL ACRYL AMIDE
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
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
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
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
EMULSION THICKENER MERITS • IDEAL FOR PIGMENT PRINTING DEMERITS • INFLAMMABLE- FIRE HAZARDS • AIR POLLUTION • HIGH COST • FABRIC SMEES DUE TO RESIDUAL k.OIL OR MTO. NOT ACCEPTABLE IN EXPORT MARKET
SYNTHETIC THICKENER CHEMICAL NATURE • HIGH MOL.Wt. COPOLYMERS OF ACRYLIC OR METHACRYLIC ACID • HAVE FREE –COOH GROUPS ON POLYMERIC CHAINS WHICH A ROLE IN VISCOSITY BUILD UP • TRADE PRODUCTS: AQUEOUS EMULSION, ACID pH • CONCENTRATION FOR PRINTABLE VISCOSIT 1-2%
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
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
PREPARATION OF THICKENER PASTE BINDER 100 PARTS WATER 80-890 PARTS SYNTH. THICKENER 10-20 PARTS LIQUOR AMMONIA TO pH 8
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 140-1500 C FOR 4-5 MIN. NO WASH
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