RESIST PRINTING UNDER REACTIVE DYES

1
RESIST PRINTING UNDER REACTIVE DYES

• REIST PRINTING PREVENTION OF DYE FIXATION AT
  THE PRINTED PORTION
• WHITE RESIST WHITE PRINT AGAINST COLOURED
  BACKGROUND
• COLOURED RESIST COLOUR PRINT AGAINST COLOUR
  BACKGROUND
• PRINCIPLE
• REACTIVE DYES FIXED ON COTTON UNDER ALKALINE
  CONDITIONS
• DYE FIXATION PREVENTED UNDER ACIDIC CONDITIONS
• SEQUENCE PRINT WITH RESISTING AENT gt DRY gt NIP
  PAD WITH DYE ALKALI gtDRY gt STEAM gt WASH gt SOAP
  gt WASH gt DRY

2
CHOICE OF ACID

• INORGANIC ACID SUCH AS HCl NOT SUITABLE DUE TO
  DANGER OF FIBRE DEGRADATION DURING STEAMING
• VOLATILE ORGANIC ACID LIKE ACETIC ACID NOT
  SUITABLE
• NON-VOLATILE ORGANIC ACID LIKE CITRIC ACID,
  TARTARIC ACID SUITABLE
• THICKENER SHOULD BE STABLE TO ACID e.g.
  MODIFIED GUAR GUM (INDALCA AGBV)

3
PRINT PASTE COMPOSITION

• CITRIC ACID 50 PARTS
• WATER 50 ml
• THICKENER PASTE 900 PARTS
• TOTAL 1000 PARTS
• PRINT gt DRY
• PAD LIQUOR COMPOSITION
• REACTIVE DYE 10-20 g/l
• RESIST SALT 10 g/l
• SOD. BICRBONATE 10-20 g/l
• NIP PAD gt DRY gt STEAM FOR 10-15 MIN. gt WASH gt
  SOAP gt WASH gt DRY

4
COLOURED RESIST

• COLOURED PRINT AGAINST COLOUR BACKGROUND
• PRINCIPLE
• INCORPORATE DYE/PIGMENT IN RESIST PASTE WHICH CAN
  BE FIXED UNDER ACIDIC CONDITION
• SIMULTANEOUS FIXATION OF GROUND COLOUR AND PRINT
  COLOUR
• PIGMENT ALONG WITH BINDER MOST SUITABLE
• PRINT PASTE COMPOSITION
• PIGMENT COLOUR 20-30 PARTS
• BINDER 100 PARTS
• EMULSION THICKENER 850 PARTS
• CITRIC ACID 50 PARTS
• TOTAL 1000 PARTS
• PRINT gt DRY gt NIP PAD WITH REACTIVE DYE ALKALI
  gt DRY gt STEAM gt WASH gt SOAP gt WASH gt DRY

5
DISCHARGE PRINTING UNDER REACTIVE DYES

• PRINCIPLE
• DISTRUCTION (CHEMICAL DECOMPOSITION) OF DYE AT
  THE PRINTED PORTION
• DISCHARGING AGENT
• THERMALLY STABLE STRONG REDUCING AGENT
• COMMON DISCHARGING AGENTS
• SODIUM SULPHOXYLATE FORMALDEHYDE (HSO2CH2O)Na OR
• ZINC SULPHOXYLATE FORMALDEHYDE
• (HSO2 CH2O) 2 Zn OR Zn(OH)(HSO2CH2O)
• (HSO2CH2O)Na H2O gt CH2OHSO3NA 2 H
• TRADE PRODUCTS
• ROGALITE C (BASF), SAFOLITE (TRANSPEK), AROSIT SR
  (CLARIANT)

6
DISCHARGING AGENTS

• CALCIUM SULPHOXYLATE FORMALDEHYDE ( RONGALIT H)
• STANNOUS CHLORIDE
• THIUREA DIOXIDE

7
SEQUENCE

• UNDYED FABRIC gt DYEING gt DISCHARGE PRINTING gt DRY
  gt STEAM gt WASH gt SOAP gt WASH gt DRY
• GROUND COLOURS
• CORRECT CHOICE OF DYES IS VERY IMPORTANT IN
  DISCHARGE PRINTING
• SUITABLE DYES USUALLY CONTAIN NN GROUP WHICH IS
  READILY ATTACKED BY REDUCING AGENTS GIVING
  COLOURLESS WATER SOLUBLE AMINES
• R-NN-R gt RNH2 RNH2
• INFORMATION RELATED TO EASE OF DISCHARGEABILITY
  IS NORMALLY GIVEN IN MANUFACTURERES SHADE CARDS

8
COLOURED DISCHARGE

• DYES STABLE TO REDUCING AGENT AND THOSE CAN BE
  FIXED DURING STEAMING IN PRESENCE OF REDUCING
  AGENT ARE INCORPORATED IN DISCHARGE PASTE
• VAT DYES ARE MOST SUITABLE

9
WHITE DISCHARGE

• GLYCERINE 10-20 PARTS
• REDUCING AGENT 30-150 PARTS
• ZnO/TiO2 30-50 PARTS
• WATER 100-150 PARTS
• OPTICAL BRIGHTENER 10 PARTS
• BRITISH GUM TO MAKE 1000 PARTS
• THIKENER PASTE
• PRINT ON DYED FABRIC gt DRY gt STEAM FOR 30 MIN gt
  WASH gt SOAP gt WASH gt DRY

10
COLOUR DISCHARGE

• VAT DYE 50-100 PARTS
• Na2CO3/K2CO3 30-40 PARTS
• Zn/Na SULPHOXYLATE
• FORMALDEHYDE 80-120 PARTS
• GLYCERINE 10-20 PARTS
• WATER 100-150 PARTS
• BRITISH GUM
• THICKENER PASTE TO MAKE 1000 PARTS
• PRINT ON DYED FABRIC gt DRY gt STEAM 30 MIN. gt WASH
  gt OXIDIZE gt WASH gt SOAP gt WASH gt DRY