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internship Dyeing

  1. 1. In the form of spinner’s package Warp preparation Weft preparation Winding (cone, Cheese) Winding (Cop,pirn) Warping(pre beam,warp) Weaving Sizing (weavers beam) Drafting, Drawing,Denting, Weaving
  2. 2. Flow chart of processing
  3. 3. Textile Chemical Processing for the Fibres (Preparatory Operations) • The fabric collected from various weaving setups, can not be used directly for manufacturing various textile products. • There are number of impurities present in the fabric such as dust, dirt, oil stains, oil and waxes, starches or other sizing materials, seed particles, and natural coloring materials. These impurities can be classified as. I. Natural Impurities & II. Added Impurities
  4. 4. Objectives of pre treatment The main objectives of preparatory treatments of textile materials are, 1. To remove all the impurities, both naturals and those added during production that may interfere in subsequent dyeing or finishing process. 2. Improve the ability of the fibers to absorb water, dyes solutions and chemicals. 3. Impart proper brightness or whiteness to fabrics according to need, especially when brilliant or pastel shades are desired.
  5. 5. Preparatory process Important Preparatory Steps for Cotton Fabric • Singeing • Desizing • Scouring • Bleaching • Mercerizing
  6. 6. SINGEING • Singeing is a process of burning off protruding fibers from the surface of the yarn of the fabric in order to improve the lustre and Smoothness of the material. Types of singeing: • Hot plate singeing machine • Roller singeing machine • Gas-singeing machine
  7. 7. DESIZING • The removal of added size material in process of sizing is known as desizing. Methods Of Desizing Hydrolic Oxidative Novel Rot steep Chlorine Solvent Enzymatic Chlorite Desizing 2000 Acid steep Bromite LT plasma Treatment
  8. 8. SCOURING • The oils and fatty acids of inorganic compounds form a layer on fabric which are hydrophobic and affect the absorbency of cloth. the process by which the water resistant layer is removed is known as Scouring. • Scouring Processes for cotton:- 1.The lime soda process 2.Caustic-soda boil 3.Treatment with soap and soda ash 4.Enzyme scouring
  9. 9. BLEACHING • Bleaching is a process by which the natural colouring matter and any other colouring matter is removed from natural fibers or process discoloration from man-made fibers. • Classification of Bleaching Agents: 1. Oxidizing bleaching agents Cl₂, H₂O₂, Na₂O₂, K₂S₂O₈, HOCl, KMnO₄, O₃ 2. Reducing bleaching agents So₂, Na₂SO₃, Na₂S₂O₄, H₂SO₃, NaHSO₃
  10. 10. Bleaching Reciepe 1. Desizing 0.3% Desize soln 0.4% Soap soln 2. Hot wash 4.5% NaoH boiling H₂O₂ 1% Stabilizer 0.25% 3. Bleaching Bleaching 20gpl Cold wash- 2 rounds HCl 1% Soda 0.5%
  11. 11. Mercerization • Mercerization process was invented by John Mercer. • In the Mercerization process, cotton fabric or yarn is treated with a cold concentrated solution of sodium hydroxide for one minute or less. In this process cotton fibers swell, untwist and their bean shaped cross section changes into a round form Mercerization improves the following properties of the cotton fabric. 1. Strength would be increased to 15-25%. 2. Enhanced luster. 3. Greater affinity to water, dyes and other chemical finishes. 4. Shrinkage control in both the direction of the fabric.
  12. 12. Dyeing • Dyeing is by far the most widely used means of applying color to textiles. • Dyes, by definition, are soluble in the medium in which they are applied, and the medium is almost always water. Immerse Textile in Dye-bath Apply Heat, Time, Chemicals to Drive Dye into Textiles Rinse to Remove Surface Dye All Dye is in Bath Most of the Dye Now on Textiles Unfixed Surface Dye Removed
  13. 13. Classification of Dyes
  14. 14. Dyeing Can Be Done at Different Stages: • Fiber Stage • Yarn Stage • Fabric Stage • Garment Stage
  15. 15. • General Principles and Terms Met in Dyeing 1) Dye Exhaustion – This describes how much of the total dye applied resides on the fiber rather than in the dye liquor. 2) Equilibrium – This is when the final or equilibrium degree of exhaustion has been reached. If the dyeing is allowed to proceed under the same conditions for a longer time, the shade of the dyed goods will remain the same. 3) Levelness and Leveling Power - levelness depends on: » Liquor ratio – The leveling power increase as the LR increases as there is more dye in the bath » Substantivity – Low substantivity favors leveling » Temperature – Higher temperature give more level dyeing » Time – Longer times give more level dyeing
  16. 16. Piece Winch (or beck) Dyeing • Fabric pieces are sewn end to end and this rope-like form is dyed in a relaxed state. • It is most widely used on knitted, woolen and worsted fabrics.
  17. 17. Piece Jig Dyeing • Fabric is treated in open width and is passed through the dye bath rather than immersed in to a dye bath and this is repeated. • There is a degree of tension on the fabric and is therefore used on woven fabrics and not knits.
  18. 18. Piece Pad Dyeing • The dye solution is applied by means of a padder and the fabric in open form is run through an open vat. • The fabric is subject to tension, so only selected fabrics can be dyed. • Advantages: System can handle thousands of yards and dye can be added automatically to provide consistency of dye color
  19. 19. Reactive Dyeing The reactive dyes are water-soluble anionic dyes, which react with hydroxyl groups of cellulose to become covalently bonded to the fiber. • The chemical reaction between a reactive dye and a cellulose fiber takes place in the presence of a base and can be summarized as follows • Offers bright colors with very good colorfastness, (particularly good washfastness and excellent light fastness). • Susceptible to damage from chlorine bleaches
  20. 20. VAT The Vat dyes are insoluble organic compounds that are not substantive to cellulose. The following steps are involved in dyeing: 1) Reduction (Vatting): Prior to dyeing they are converted to their soluble form (leuco soluble vat dye) by means of reduction in the presence of a strong base. 2) Dyeing: In this soluble form, they are substantive to cellulosic fibers, and can be applied to them. 3) Oxidation: Once inside the fibers, uniformly distributed, the Vat dyes are then oxidized and converted back to their original insoluble form. 4) Soaping: to achieve a stable shade.
  21. 21. VAT • The soft water throughout the dyeing stage is a must with Vat dyes, since the soluble Leuco salts form insoluble salts with Calcium or Magnesium ions as well as with transition metals. • A wide choice of colors with good to excellent colorfastness is available, although their lightfastness may be somewhat inferior.
  22. 22. Direct • Direct dyes are soluble anionic dyes. • The Direct dyes are so called because they were the first dyes to dye cellulosic fibers directly without the need for a pre- treatment of the fibers with a mordant. • The mechanisms by which direct dyes become attached to cellulose is assumed to be through the formation of a large number of weak attractions between the dye and the fiber. • Direct dyes exhibit relatively good colorfastness to sunlight, and some are considered to have excellent lightfastness. However colorfastness to washing is poor and therefore not appropriate for frequently washed apparel. • The problem of poor washfastness can be improved to some degree by formaldehyde after treatment. Direct
  23. 23. Properties of Dye Stuff
  24. 24. SHRINKAGE CONTROL FINISHES • A reduction in the length or width of a fibre, yarn or fabric is known as shrinkage. Growth occurs when a fabric increases in dimension. It is essential to know the shrinkage of the fabrics in both the directions ( Warp wise and weft wise) to determine construction and design of garment • Causes of Shrinkage • Intermolecular structure of fibres • Yarn twist • Fabric construction (Yarns / inch) • Weave / knit structure
  25. 25. Compressive Shrinkage (Sanforization) • In Compressive Shrinkage process, the fabric is dampened and is placed on a machine equipped with a continuous thick woolen felt blanket. The blanket travels around a smaller roller carrying the • fabric with it as it • stretches around • the curve of the roller.
  26. 26. ETP It is a process design for treating the industrial waste water for its reuse or safe disposal to the environment. • Influent: Untreated industrial waste water. • Effluent: Treated industrial waste water. • Sludge: Solid part separated from waste water by ETP. Treatment levels: 1. Prelimnary 2. Primary 3. Secondary 4. Tertiary (or advanced) • Treatment mechanisms: 1. Physical 2. Chemical 3. Biological
  27. 27. Conclusion • I learnt all the techniques and process of textile processing. • This Internship help in knowing the various machine used for processing. • Due to secrecy act, all the data on recipe, method & activities has not been supplied & hence the data given regarding to this do not resemblance to the actual data. • The whole process is not possible to bind in such a small frame as this report, hence our effort spenton summarizing, not describing them
  28. 28. References • Textile chemical processing, Students Handbook Central Board Of Secondary Education Shiksha Kendra, 2, Community Centre, Preet Vihar, Delhi-110301 • Wet Processing Technology-Internship Report https://www.scribd.com/document/294278091/Wet-Processing- Technology-Internship-Report-pdf accessed on 28th, Jan 2018 • Textile Internship Report - arvind denim division https://www.scribd.com/doc/104909847/2012-Textile-Internship- Report-arvind-denim-devision • Internship report on dyeing http://www.assignmentpoint.com/science/textile/internship-report- on-dyeing.html Accessed on 29th, Jan 2018 • Srini Venkatraman, 2006 Bureau Veritas file:///C:/Users/user/Downloads/dyingprintingfinishing- 100504132149-phpapp01.pdf Accessed on 30/01/2018
  29. 29. Thanking you