Vat dye
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not complete but little definition for vat dyes

not complete but little definition for vat dyes

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Vat dye Presentation Transcript

  • 1. VAT DYES
    Except Deep Red
    7/2/2008
    1
  • 2. Introduction
    1
    Chemical Structure of Vat Dyes
    2
    Dyeing Structure of Vat Dyes
    Treatments After Exhaustion of Vat Dyes
    Semi and Fully Continuous Method
    3
    5
    6
    Method of Dyeing
    4
    Overview
    7/2/2008
    2
  • 3. Wet on Wet Process
    7
    Fixation Process
    8
    Package Dyeing
    Correction of Faulty Dyeing
    Indigo Dyeing for Denim
    Solublised VAT Dyes
    9
    11
    12
    13
    Dyeing of Knit Goods
    10
    Overview
    7/2/2008
    3
  • 4. Introduction
    1
    • Dyeing produced with the vat dyes have the highest overall fastness properties.
    • 5. All of these dyes have good fastness against
    • 6. Wet treatments
    • 7. Crocking
    • 8. Light fastness in the region of 6 to 7.
    • 9. The vat dyes can also withstand oxidizing agents like
    • 10. Hydrogen peroxide (H202)
    • 11. Sodium Chloride (NaCl)
    • 12. Hypochlorite (--OCl)
    7/2/2008
    4
  • 13. Introduction
    1
    • the vat dyes are extensively used for dyeing yarn
    • 14. THIS CLOTH can undergo the pretreatment processes like
    • 15. Alkali Boiling
    • 16. Bleaching
    • 17. Mercerizing
    Without any damage to the dyed yarn.
    After the introduction of hydrogen peroxide- tolerant reactive dyes
    • Yarn dyeing has been taken over by the reactive dyes.
    • 18. Because reactive dyes less expensive , easier to apply.
    • 19. Vat dyes are still popular on account of the all round high fastness properties.
    • 20. VAT DYES ARE COMMONLY USED FOR:
    • 21. Superior Quality Shirting Material
    • 22. Military Uniforms
    • 23. Furnishings, Curtain, Toweling etc.
    7/2/2008
    5
  • 24. Introduction
    1
    • there are about 60 vat dyes in the market
    • 25. That cover the entire Gamut(range) of shades except Deep Red Colors.
    • 26. VAT DYES ARE ESSENTIALLY Insoluble Polycyclic Aromatic Compound:
    • 27. Containing Two or more pair of QUINONE GROUPS
    • 28. Indigo and Tyrian Purple belongs to this family.
    • 29. VATTING: In order to apply cellulosic Fibers
    • 30. VAT PIGMENTS are made water soluble by reducing to HYDROQUINONE Forms in an alkaline media.This process Known as Vatting.
    • 31. Vatting Term referring to a historical link with the vegetable Indigo Dye that used to reduced in WOODEN VATS with natural reducing agents like sugar.
    • 32. PRESENT VATTTING CHEMICALS ARE:
    • 33. Sodium Hydroxide
    • 34. Sodium Dithionate(Na2 S2 O4) a strong reducing agent one with high reduction potential. Commonly termed in Industry as Sodium Hydro Sulphite or Simply HYDROS.
    • 35. Sodium Dithionate reduces the KETO GROUPS into the ENOL Form
    • 36. Sodium Hydroxide forms sodium salts of the ENOL to make the DYES WATER SOLUBLE.
    7/2/2008
    6
  • 37. Introduction
    1
    • PRESENT VATTTING / REDUCING CHEMICALS ARE:
    • 38. Sodium Hydroxide
    • 39. Sodium Dithionate(Na2 S2 O4) a strong reducing agent one with high reduction potential.
    • 40. Commonly termed in Industry as Sodium Hydro Sulphite or Simply HYDROS.
    • 41. Sodium Dithionate reduces the KETO GROUPS into the ENOL Form
    • 42. Sodium Hydroxide forms sodium salts of the ENOL to make the DYES WATER SOLUBLE.
    • 43. Caustic Soda Also NEUTRALISE THE ACIDIC Decomposition products of the reducing agent ‘DITHIONITE’ produced during vatting and Dyeing.
    7/2/2008
    7
  • 44. Introduction
    1
    • PRESENT VATTTING / REDUCING CHEMICALS ARE:
    • 45. Quantity of Reducing Agent Depend upon
    • 46. No. of KETO groups Present in the Dye Molecule
    • 47. To the extent/ amount of exposure or the dye bath to AIR.
    • 48. Reduction is Accompanied by
    • 49. Change in Color that is due to alteration in the conjugation of DOUBLE BONDS.
    • 50. The reduced indigo has a PALE SHADE and so it was called the LEUCO(white) dye.
    7/2/2008
    8
  • 51. Chemical Structure of VAT Dyes
    2
    • Around 1900 Rene Bohn in GERMANY
    • 52. accidently prepared a blue dye from ANTHRAscene, which he named as an INDANthrene dye. Soon after this breakthrough
    • 53. Bohn and his Coworkers synthesize many other VAT DYES.
    • 54. THE VAT DYES ARE OFTEN CLASSIFIED AS:
    7/2/2008
    9
  • 55. DYEING Structure of VAT Dyes
    3
    • Sodium Salts (Nacl) of the Reduced or Leuco VAT Dyes behave like:
    • 56. Direct dyes
    • 57. As for as adsorption on the cellulose fibres is concerned
    • 58. But the ANTHRAquinone derivatives have
    • 59. High intrinsic substantivity
    • 60. In spite of lack of linearity and
    • 61. Hydrogen bonding groups attributed
    • 62. to the molecular complexity
    • 63. And CO-PLANARITY of the VAT dyes.
    • 64. As a High Concentration of SODIUM IONS from Caustic Soda(NaoH) and Sodium Dithionate(Na2 S2O4)
    • 65. Already exist in the Reduced Bath.
    • 66. The VAT dye tend to have HIGH RATE of adsorption
    • 67. And EXHAUSTION in the initial stage of Application.
    • 68. The RAPID ADSORPTION of dye in the first few minutes:
    • 69. Technically termed as “HIGH STRIKE” value.
    • 70. This tendency require a careful attention as well as ADDITION of RETADING agents to obtained level dyeing.
    7/2/2008
    10
  • 71. DYEING Structure of VAT Dyes
    3
    • After the adsorption of the LEUCO DYES
    • 72. AN OXIDIZING AGENT IS ADDED TO THE BATH
    • 73. That regenerates the VAT PIGMENT inside the fibres.
    • 74. Finally, to achieve full fastness properties and to develop the proper shade, the dyed goods are
    • 75. THOROUGHLY SOAPED AT BOIL.
    • 76. VAT dyes three main classes for APPLICATION PUPOSES.
    7/2/2008
    11
  • 77. DYEING Structure of VAT Dyes
    3
    7/2/2008
    12
    • Where I stands for Indanthrene and N for Normal
    • 78. In their Leuco forms Have High substantively for the cellulosic fibres.
    • 79. These needs High Alkalinity for Dissolution
    • 80. And are dyed at about 75o c.
    • 81. Where I stands for Indanthrene and W for Warm
    • 82. In their MODERATE substantivity for cellulosic fibres.
    • 83. These needs MEDIUM Alkalinity for Dissolution
    • 84. And are dyed at about 45o c TO 75o c.
    • 85. Needs Electrolytes for complete EXHAUSTION of the dye.
  • DYEING Structure of VAT Dyes
    3
    7/2/2008
    13
    • Where I stands for Indanthrene and K for KALT / COLD
    • 86. Have LOW substantivity for the cellulosic fibres.
    • 87. These needs moderate Alkalinity for Dissolution
    • 88. And are dyed at low temperature about 20o c to 30o c..
    • 89. Needs in a Higher concentration Electrolytes than class II for complete EXHAUSTION of the dye.
    • 90. Dyes of the IK Group other than the Indigo, are Not much used now a days.
    • 91. Some vat dyes like BLACKS do NOT into the above mentioned three groups and are dyed by a special method
  • METHOD DYEING
    4
    • In Batch dyeing of fabric, VAT dyes are normally applied in the
    • 92. Reduced in a JIGGER.
    • 93. For continuous processes,
    • 94. Fabric is PADDED in stable dispersion of very finely divided vat pigments often termed as MICRO-DISPERSIONS.
    • 95. After drying the dye padded fabric, it is reacted with an ALKALINE REDUCING SOLUTION in a padder to VAT PIGMENT into water-soluble LEUCO FORM
    • 96. LEUCO FORM diffuses into the fibre.
    7/2/2008
    14
  • 97. METHOD DYEING
    4
    • REDUCED VAT DYEING:
    • 98. This process is applicable for
    • 99. Batch wise dyeing WOVEN and KNIT fabrics
    • 100. Also for YARNs in hank or package form.
    • 101. REDUCTION OF the dye is faster in the STOCK VAT
    • 102. BECAUSE
    • 103. Concentration of the dye and reducing chemicals is higher than LONG BATH.
    7/2/2008
    15
    The dye is first reduced into SOLUBLE FORM.
    In the bath(long liquor)
    Or in the stock vat
    Before bringing it in contact with substrate
  • 104. METHOD DYEING
    4
    • REDUCED VAT DYEING:
    • 105. THE MORE Difficult to reduced CLASS I dyes:
    • 106. Vatted by the STOCK VAT method.
    • 107. This dispersion at optimum temperature
    • 108. Stirred for 10 minutes. When reduction is COMPLETE.
    • 109. SOFT WATER must for dissolving and as far as dyeing.
    • 110. Dyeing in HARD WATER causes precipitation (useless product) COUNTER THIS PROBLEM by use of SQUEStering AGENT.
    7/2/2008
    16
    Dye is pasted with the dispersing agent. And soft water
    And then the required quantities of
    Caustic Soda(NaoH)
    And
    DI-THIONATE(S2O4)
    Are added as per manufacturer literature.
  • 111. METHOD DYEING REDUCED VAT DYEING:
    4
    7/2/2008
    17
  • 112. METHOD DYEING REDUCED VAT DYEING
    4
    • THE FOLLOWING TABLE WILL GIVE A
    • 113. GENERAL IDEA OF CONCENTRATION
    • 114. OF rducing and exhausationchemicalsrequired in the bath at a liquor ratio of 10:1
    7/2/2008
    18
  • 115. METHOD DYEING REDUCED VAT DYEING
    4
    • For the Class I dyes,
    • 116. a nonionic retarding agent (ALKO-Xylated type)
    • 117. Is often added that forms a complex with the REDUCED dye and release it gradually as the bath is exhausted,
    • 118. addition of the Retarding or LEVELLING agent is more necessary
    • 119. When dyeing mercerized COTTON, Regenerated RAYON
    • 120. And for PALE SHADES
    • 121. And also in LOW LIQUOR ratios.
    • 122. These LEVELLING Agent reduce the ultimate dye- uptake slightly,
    7/2/2008
    19
  • 123. METHOD DYEING REDUCED VAT DYEING
    4
    7/2/2008
    20
  • 124. METHOD DYEING REDUCED VAT DYEING
    4
    • Some Dyes during dyeing
    • 125. OVER – REDUCED
    • 126. Their SHADES becomes LIGHTER or even ALTERED.
    7/2/2008
    21
  • 127. METHOD DYEING REDUCED VAT DYEING
    4
    Dyeing is started at temperature of 20o C.
    • Which is gradually raised to the optimum.
    • 128. Dyes of IN and IW groups temperature
    • 129. can be raised to 80o C
    • 130. The Dyeing Continued for 45 TO 60 minutes.
    • 131. ELECTROLYTE is added in portions about 20 Minutes
    After the dye Liquor reaches the MAXimum Temperature.
    In case or CLASS III
    • ELECTROLYTE added at beginning
    • 132. And dyeing is carried out in a cooling BATH after attaining TEMP of 45o C.
    • 133. However SPECIAL REDUCING AGENTS of the HYDROXY-Alkyl-Sulphinate type may have to be used that can withstand decomposition at these HIGH Temperature.
    7/2/2008
    22
  • 134. TREATMENTS AFTER EXHAUSTION OF DYES
    5
    AFTER EXHAUSTION OF THE VAT DYES
    7/2/2008
    23
  • 135. TREATMENTS AFTER EXHAUSTION OF DYES
    5
    AFTER EXHAUSTION OF THE VAT DYES
    7/2/2008
    24
  • 136. TREATMENTS AFTER EXHAUSTION OF DYES
    5
    AFTER EXHAUSTION OF THE VAT DYES
    7/2/2008
    25
  • 137. TREATMENTS AFTER EXHAUSTION OF DYES
    5
    AFTER EXHAUSTION OF THE VAT DYES
    7/2/2008
    26
  • 138. TREATMENTS AFTER EXHAUSTION OF DYES
    5
    AFTER EXHAUSTION OF THE VAT DYES
    7/2/2008
    27
  • 139. Semi and Fully Continuous Dyeing Method
    6
    THE PRINCIPLE OF THIS TECHNIQUE
    • TO pad the well prepared fabric
    • 140. With a very fine dispersion (PARTICLE SIZE 0.5 – 1 um) of VAT PIGMENT.
    • 141. Then to convert the absorb pigment into LUECO FORM
    • 142. This is followed by
    • 143. OXIDATION
    • 144. SOAPING in a Washing Range
    • 145. The MAIN ADVANTAGE of this process over the reduced-VAT method are as under.
    • 146. A) HIGH PRODUCTIVITY
    • 147. B) BETTER LEVELLING
    • 148. C) GOOD PENETRATION
    7/2/2008
    28
  • 149. Semi and Fully Continuous Dyeing Method
    6
    Different steps involve in the APPLICATION are:
    PADDING:
    Padder should be mechanically perfect
    And exert even pressure throughout the
    Width of the fabric.
    The pigment dispersion normally contains
    • a migration inhibitor and
    • 150. a wetting agent.
    • 151. The latter is added for quick wetting of the fabric.
    7/2/2008
    29
  • 152. Semi and Fully Continuous Dyeing Method
    6
    Different steps involve in the APPLICATION are:
    2. DRYING:
    It is not necessary for Light Shades
    But it HELPS IN LEVELLING and improving colour yield.
    It may be done at
    • Combination of INFRA- RED
    • 153. HOT FLUE or
    • 154. CYLINDER DRYER
    • 155. Incase the cylinder are used
    • 156. The IR-predryer is must
    • 157. First few cylinder Teflon Coated as to reduce staining.
    • 158. Temp 100oC first few cylinders to minimize Migration and two sided effect.
    7/2/2008
    30
  • 159. Semi and Fully Continuous Dyeing Method
    6
    Different steps involve in the APPLICATION are:
    3. DEVELOPMENT:
    Method are used for both Development of the DYE PIGMENT:
    • BOTH the batch and continuous.
    • 160. In the BATCH PROCESS
    • 161. Reduction and
    • 162. Adsorption
    Of the dye can be carried out on a Jigger.
    • DONE in the reduced dyeing method, after ADDING
    • 163. Alkali and Reducing Agent
    • 164. IF variation in SHADE due to BLEEDING in not totally eliminated
    • 165. In the CHEMICAL PADDER 5 – 10 % of the bath is made with the pad liquor
    7/2/2008
    31
  • 166. Semi and Fully Continuous Dyeing Method
    6
    Different steps involve in the APPLICATION are:
    3. DEVELOPMENT: CONTINUOUS PROCESS
    7/2/2008
    32
  • 167. 7/2/2008
    33
    Semi and Fully Continuous Dyeing Method
    6
    OXIDATION AND SOAPING
    In the Continuous Process,
    In a WASHING RANGE
    In which fabric is treated in the following different sequences:
  • 168. 7/2/2008
    34
    CORRECTION OF FAULTY DEING
    7
    Fauls are usually corrected by
    Levelling Out
    Partial Stripping or Cross Dyeing
    However kept in mind LEUCO VATS have a very high affinity with cotton fibers and so difficult to strip off the dyed goods.