Presentation on Dyeing

Presentation on Dyeing

• 1.
  SHYAMOLI TEXTILE ENGINEERINGCOLLEGE
• 3.
  Contents:  Defination  Objectives Theory of dyeing  Various types of dyes  Flow chart of Dyeing process  Dyeing machines  Dyeing faults  Causes of Dyeing defeats
• 4.
  DYEING:  The processby which a textile material is to be changed physically or chemically , so that it looks mono uniform colored is called dyeing.
• 5.
  Objectives of Dyeing: To increase the attractiveness of the textile goods.  To make the fabric suitable for various usage.  To make the textile goods suitable for decorative purposes.
• 6.
  The whole processof dyeing is completed by 4 steps: 1) Dye molecules comes to the fabric surface from the dye bath. 2) Fiber absorbs the dye molecule from the outer surface of the fiber to the internal surface of the cellulose. 3) Migrates the dye molecules everywhere of the fiber molecules. 4) Fixing the dye molecules to the fiber molecules by hydrogen bond.
• 7.
  Flow chart ofDyeing process: Grey textile material Singeing Desizing Scouring Bleaching Mercerizing Dyeing/Printing Finishing Marketing
• 8.
  Various classes andtypes of dyes :  Acid Dyes  Basic (Cationic) Dyes  Synthetic Dyes  Direct Dyes  Disperse Dyes  Sulfur Dyes  Mordant Dyes  Reactive Dyes  Metalized Dyes  Gel Dyeing  Developed Dyes  Azo Dyes  Aniline Dyes  Vat Dyes
• 9.
   Acid dyesare water-soluble anionic dyes that are applied to fibers such as silk, wool, nylon.  Basic dyes are water-soluble cationic dyes that are mainly applied to acrylic fibers.  Direct dyeing is done in a neutral or slightly alkaline dye bath with the addition of sodium chloride (NaCl) or sodium carbonate(Na2CO3). It is used on cotton, paper, leather, wool, silk and nylon.
• 10.
   Azoic dyeingis a technique in which an insoluble Azo dye is produced directly onto or within the fiber.  Sulfur dyes are inexpensive dyes used to dye cotton with dark colors. Dyeing is effected by heating the fabric in a solution of an organic compound.  Vat dyes are essentially insoluble in water and incapable of dyeing fibers directly.
• 11.
   Mordant dyesrequire a mordant, which improves the fastness of the dye against water, light and perspiration.  Reactive dyes utilize a chromophore attached to a substituent that is capable of directly reacting with the fiber substrate.
• 12.
  Dyeing Machine: According todyeing process: 1) Open dyeing machine 2) Enclosed dyeing machine According to material and liquor movement: 1) Material move but liquor does not circulate i.e; jigger 2)Liquor circulate but materials does not move i.e; all package dyeing machine. 3)Both materials and liquor circulate i.e; jet dyeing machine
• 13.
  Knit dyeing byjet dyeing machine Knit dyeing :
• 14.
  Sequence of Operationfor Knit Fabric Dyeing: Grey fabric inspection ↓ Batching ↓ Fabric turning ↓ Loading to the m/c ↓ Pre-treatment (Scouring & Bleaching) ↓ Dyeing ↓ Dewatering ↓ Drying ↓ Compacting & Calendaring ↓ Final inspection & packing
• 15.
  Faults of Dyeing: Uneven Dyeing  Batch to Batch Shade variation  Patchy dyeing effect  Roll to roll variation or Meter to Meter variation  Crease mark  Dye spot  Wrinkle mark  Softener Mark
• 16.
  Dyeing Faults Major dyeingfaults which occur during are mentioned below:  Uneven Dyeing: Due to uneven scouring and uneven bleaching. Lack of control dyeing machine.  Batch to Batch Shade variation Improper Temperature. Improper time of dyes & chemicals.  Patchy dyeing effect Faulty injection of alkali. Improper addition of color. Due to hardness of water.
• 17.
   Crease mark: Pooropening of the fabric rope If pump pressure & reel speed is not equal Due to high speed m/c running  Dye spot: Improper Dissolving of dye particle in bath. Improper Dissolving of caustic soda particle in bath.