Chap 2 Dyeing Process in textile fabric.

Dyeing process

1. FD4006 : TEXTILE SCIENCE AND TECHNOLOGY Semester III B.DES.

2. UNIT II PART 1- STAGES OF DYEING

3. Content…. Introduction Stage of dyeing Dyeing types and it’s Process, Effects on fabrics, Advantage, And Use Of Different Preparatory. Processes Done On Textiles For The Dyeing And Printing: Singeing, Desizing , Boiling , Scouring, Souring, Bleaching and Mercerization . 28-09-2021 Fouzia Mirza 3

4. INTRODUCTION. 28-09-2021 Fouzia Mirza 4 https://www.youtube.com/watch?v=QHgNoSYlhYs https://www.youtube.com/watch?v=9OHbJQ90hfY

5. Video Links Cotton : https:// www.youtube.com/watch?v=QHgNoSYlhYs Linen: https ://www.youtube.com/watch?v=- ZrZZefkohE Silk : https:// www.youtube.com/watch?v=b8rX5DRusNI Polyester : https:// www.youtube.com/watch?v=zYkglUysDKk Weaving: https://www.youtube.com/watch?v=worKmsWZqYE Handloom: https://www.youtube.com/watch?v=LBTRkaq0rFM Powerlooms : https://www.youtube.com/watch?v=TyhDkd8Iabs 28-09-2021 Fouzia Mirza 5

6. Video Links Shearing and cropping: https :// www.youtube.com/watch?v=shPjEYi1zlM Singeing : https:// www.youtube.com/watch?v=StcDo7Y1Eeg Desizing: https:// www.youtube.com/watch?v=BidcXjaQUd8 Scouring: https:// www.youtube.com/watch?v=pWGzTVI24gA Dyeing ( Tie- Dyeing): https:// www.youtube.com/watch?v=8R4lAladUj0 Dyeing: https :// www.youtube.com/watch?v=8R4lAladUj0 28-09-2021 Fouzia Mirza 6

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8. 28-09-2021 Fouzia Mirza 8 CLASSIFICATION OF TEXTILE FIBRE

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10. INTRODUCTION OF WET PROCESSING. 28-09-2021 Fouzia Mirza 10

11. INTRODUCTION OF WET PROCESSING. The wet processing is a term that involves the mechanical and chemical treatment to improve the aesthetic value of the fabric, yarn, fiber. The wet processing sector can be divided into three distinct sections. Preparatory process. Coloration process. Finishing process. Lastly Inspection and shipping 28-09-2021 Fouzia Mirza 11

12. 28-09-2021 Fouzia Mirza 12 Dyeing and Printing Shearing and Cropping Grey Stitching Singeing Mercerizing Bleaching Scouring Desizing Finishing Final Inspection

13. 28-09-2021 Fouzia Mirza 13 Singeing For Dyeing and Printing Pre-treatment Process Pre-treatment processes can be carried out with fibres, yarns or fabrics. It   enables subsequent processing of the material, which needs to be prepared to accept dyes and functional chemicals. This is done in a multi-step process. Exactly which steps the fabric goes through depends on the type, or blend of fibre, and how it will be treated afterwards. In some cases pre-treated fabrics are manufactured for later garment dyeing

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15. Basic Textile Terms and Definitions Dyestuff is organic or inorganic substances which can absorb light and reflect some lights to show color. Actually, the dyestuff is water soluble substances . Pigment is a substance that can absorb light and reflect some lights to show color but it is water insoluble substances. Normally it is used for printing (with the presence of binder) or mass-coloration of the synthetic fibers. 28-09-2021 Fouzia Mirza 15

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19. Stages of Dyeing 28-09-2021 Fouzia Mirza 19

20. Different Stages of Dyeing Textiles Textiles may be dyed at any stage of their development from fibre into fabric or certain garments by the following methods ; 28-09-2021 Fouzia Mirza 20

21. Stock Dyeing Stock dyeing refers to dyeing staple fibres before they are spun. Here the packed   fibres are removed from the bales and then packed in large vats to be circulated with dye liquor at elevated temperature. In stock dyeing, which is the most effective and expensive method of dyeing, the colour is well penetrated into the fibres and does not crack readily. Stock dyed fibres does not spin as readily as undyed fibre because it loses some of its flexibility, but lubricants added in the final stage overcome most of this difficulty. 28-09-2021 Fouzia Mirza 21

22. Solution pigmenting or Dope dyeing :   A process called solution pigmenting or dope dyeing has   been used for manmade fabrics ranging from rayon through saran and glass fibres . In dope dyeing, dye is added to the spinning solution before it is extruded through the spinnerets into filaments . This method also gives a greater degree of color fastness . Effective results have been obtained by this method. 28-09-2021 Fouzia Mirza 22

23. Top dyeing Top dyeing is adopted in the worsted industry. Top is wool that has been combed to   take out the short fabrics, in a rope like form about 1.2 inches (30mm thick). The top is then wound on perforated spools and the dye liquor is circulated through it. Perfect even dyeing is possible in this method. 28-09-2021 Fouzia Mirza 23

24. Yarn Dyeing Dyeing done at yarn stage is known as yarn dyeing. Yarn dyed fabrics are usually   deeper and richer in colour . The primary reason for dyeing in the yarn form is to create interesting checks, stripes and plaids with different coloured yarns in the weaving process. Some typical yarn-dyed fabrics are multi colored gingham, madras, brocade and multi-colored weft knits. Yarn dyeing is also used in special cases for solid-color fabrics. Yarns may be dyed in different forms such as, Skeins, Packages and Beams. 28-09-2021 Fouzia Mirza 24

25. Yarn Dyeing Skein Dyeing Skein Dyeing consists of immersing large, loosely wound hanks (skeins) of yarns into dye vats that are especially designed for this purpose. Soft, lofty yarns such as hand knitting yarns are usually skein dyed. Skein dyeing is the most costly yarn-dye method. Package Dyeing In Package Dyeing, yarn is wound on a small perforated spool or tube called a package. Many spools fit into the dyeing machine in which the flow of the dye bath alternates from the centre to outside, and then form outside to the centre of the package . 28-09-2021 Fouzia Mirza 25

26. Yarn Dyeing Beam Dyeing Beam Dyeing is a much larger version of package dyeing. An entire warp beam is wound onto a perforated cylinder, which is then placed in the beam dyeing machine where the flow of the dye bath alternates as in package dyeing . 28-09-2021 Fouzia Mirza 26

27. Fabric Dyeing Piece Dyeing :   Bulk of fabrics are dyed in this method. Piece dyeing is thoroughly satisfactory as   regards evenness, penetration and overall fastness. Fabrics may be piece dyed whether it is composed of only one kind of fibre or yarn or blends of different fibres or combinations of different yarns. When the fabric is made of one kind of fibre or yarn, the dyeing is not complicated because the one appropriate dye is used. 28-09-2021 Fouzia Mirza 27

28. Fabric Dyeing If the fabric is of a blend or combination of different yarns, then special procedures are required where different dyes that are particular for each fibre need to be selected. They are union dyeing and cross dyeing .   Union Dyeing : Different fibres may require different dyes to obtain the color, this may be done by   putting the appropriate colour dye that is specific to each type of fibre into one bath .   Cross Dyeing:  Cross dyeing of goods may be accomplished in any one of the several ways. One   method is a combination of stock dyeing or of yarn dyeing with subsequent fabric dyeing . 28-09-2021 Fouzia Mirza 28

29. Garment Dyeing Garment Dyeing is the dyeing of completed garments. The types of apparel that can be dyed are mostly non-tailored and simpler forms, such as sweaters, sweat-shirts, T-shirts, hosiery, and pantyhose. The effect on sizing, threads, zippers and snaps must be considered. Tailored items such as suits or dresses cannot be dyed as garments because the difference in shrinkage of the various components and linings distort and miss-shape the article. Garment dyeing is done by placing a suitable number of garments (usually about 24 sweaters or the equivalent, depending on weight) into a large nylon net bag. The garments are loosely packed. From 10 to 50 of the bags are placed in large tubs containing the dye bath and are kept agitated by a motor driven paddle in the dye tub. The machine is appropriately called a Paddle Dyer . 28-09-2021 Fouzia Mirza 29

30. Types of Dyed Garments Hosiery Pantyhose Sweaters T-Shirts 28-09-2021 Fouzia Mirza 30

31. Methods of Dyeing Solution Dyeing Stock Dyeing Hank/Skein Dyeing Package Dyeing Beam Dyeing (Yarns ) Winch/Beck Dyeing Jet Dyeing Jig Dyeing Pad Dyeing Beam Dyeing (Fabric) Paddle Dyeing 28-09-2021 Fouzia Mirza 31

32. Solution (Dope) Dyeing As the name suggests, the dyestuff is added to the chemical solution of the man-made fiber. When the fiber filament appears from the spinnerette , the filament appears colored. The advantage of this technique is that the colorfastness property of the textile will be excellent. 28-09-2021 Fouzia Mirza 32

33. Stock Dyeing The loose fibers are immersed in the dyebath before the processes of blending, combing, carding, and spinning take place. The advantages of this technique are as follows: Excellent colorfastness property to the textile This allows creating a yarn of multiple colors to give a melange look in the fabric. Uniform distribution of the dyestuff This is the costliest method of dyeing. The reason is that the dyeing is done prior to manufacturing of the yarn, which will incur some wastage of the fibers, depending on the quality of the yarn required for further processing . 28-09-2021 Fouzia Mirza 33

34. Beam Dyeing (Yarns ) In beam dyeing, the warp yarns are wound on cylindrical beams which are placed in a machine. The dyebath is run in a center-to-outside and then in an outside-to-center motion to get the desired depth of the color 28-09-2021 Fouzia Mirza 34

35. Winch/Beck Dyeing The fabric ends are stitched together to make a continuous piece. The fabric is then immersed in the dye liquor in a slack condition and is rotated by a roller in the dye liquor. The dye, in this case, is stationary whereas the fabric moves. 28-09-2021 Fouzia Mirza 35

36. Jig Dyeing / Jigger Dyeing This technique involves dyeing at the fabric stage . In this technique, the fabric in an open-width form is held up on two rollers in a machine called a jig dyeing machine or a jigger. The fabric is unwound from one side, immersed into the dyebath and then wound onto the other side. The action is repeated until the desired color is obtained on the fabric . 28-09-2021 Fouzia Mirza 36

37. Jig Dyeing / Jigger Dyeing 28-09-2021 Fouzia Mirza 37

38. Piece Jet Dyeing This technique involves dyeing at the fabric stage. The fabric is placed in a rope-form in a tube-like containment. There are pressure jets in the container and the dye liquor is penetrated through the fabric through these jets. 28-09-2021 Fouzia Mirza 38

39. Pad Dyeing This technique involves dyeing at the fabric stage. The fabric is wound on rollers in a pad dyeing machine in an open-width form. The fabric in its long length is then made to pass through a trough which contains the dye liquor, and moved along the roller. It is a continuous process and the excess dye is squeezed out of the fabric . 28-09-2021 Fouzia Mirza 39

40. Beam Dyeing (Fabric ) This technique involves dyeing at the fabric stage. Just like in the yarn stage dyeing method, the fabric is wound on large cylindrical beams. The dye liquor is then pushed through the beams to impart color to the fabric . 28-09-2021 Fouzia Mirza 40

41. Technique for the Garment Stage There is only one main dyeing technique that occurs during the garment stage. Paddle Dyeing 28-09-2021 Fouzia Mirza 41

42. Paddle Dyeing This technique involves dyeing at the garment stage after the construction of the garment. The garments are immersed in a dye solution placed in a large container in the paddle dyeing machine. The garments are loosely packed and a motor driven paddle circulates the dye solution in the container to impart color to the garments. This technique can also be used for dyeing individual components of a garment. In that case, the dyeing would take place before the construction of the fabric . 28-09-2021 Fouzia Mirza 42

43. Classification of Dyes Dyestuffs can be classified by many methods as follows : 1 . by their ionic (e.g. cationic, anionic and non-ionic ) 2 . by their fiber dye-abilities (e.g. on cellulosic, protein, polyester, polyamide etc .) 3 . by their names (e.g. acid, direct, disperse, reactive, basic etc .) 4 . by their chemical structures (e.g. azo , anthraquinone , stilbene etc .) 5 . by their origins (e.g. natural, synthetic ) 6 . by their colors (e.g. red, green, black etc.) 28-09-2021 Fouzia Mirza 43

44. Classification based on Fiber dye-abilities 28-09-2021 Fouzia Mirza 44

45. Classification based on Origin A) Natural and B)Synthetic dyes. 28-09-2021 Fouzia Mirza 45

46. A). Natural Dyes Natural dyes are taken from three sources namely plants, animals and minerals.   Vegetable Dyes :  Around 4000 years back Egyptians have used Indigo dyes, that are obtained   from stems and leaves of a particular plant. Alizarin dyes are taken from roots of madder plant. Logwood dyes are extracted from the trees which give black colour to silk and cotton fabrics. 28-09-2021 Fouzia Mirza 46

47. 28-09-2021 Fouzia Mirza 47 Indigo Dyeing Alizarin Dyeing

48. A). Natural Dyes    Animal Dyes :  Cochineal dye was extracted from an insect - Coccus Cacti. The dye was taken after   killing the female insects. These dyes were used for imparting red and orange colours in silk and wool fabrics. Tyrian purple dye was made out of shell fish . Mineral Dyes :  Natural minerals yield certain varieties of dyes for example Iron Buff . 28-09-2021 Fouzia Mirza 48  

49. 28-09-2021 Fouzia Mirza 49 Tyrian Purple

50. B). Synthetic Dyes Synthetic dyes were first derived from coal tar in 1856. Later innumerable dye compounds were made from coal tar, and are constantly being improved as to beauty of colour and colourfastness . They are as follows : 28-09-2021 Fouzia Mirza 50    

51. Direct Dye or Salt Dye : Direct dye can be applied to animal fibre as well as vegetable fibre fabrics but are   generally applied to cotton and are known as Direct Cotton Dye . These dyes are soluble in water and are chiefly composed of amines and phenols. Because a little salt is added to the solution while dyeing with direct dyes, these are also called Salt Dyes . A further treatment with acetic acid and sodium dichromate is necessary to make them fastness to washing . The dye colours often have only fair fastness to light, poor fastness to washing and are not very bright . 30-09-2021 Fouzia Mirza 51    

52. Basic Dyes (Cationic Dyes) The first coal-tar dye was a so-called basic dye. Basic dyes are salts of organic colour   bases. It was developed to give many bright shades of silk and wool . Basic dyes are known as cationic dyes, the same are used with a mordant, Tannic acid, for cotton, linen, acetate, nylon, polyester and acrylics. This dye gives beautiful colour but is not fast to sunlight, washing and perspiration . 28-09-2021 Fouzia Mirza 52  

53. Acid (Anionic) Dyes   Acid dyes are the sodium or calcium salts of colour organic acids. They are   used mostly on wool and silk. Acid dyes are inexpensive and fairly fast to light, but they are not fast to washing. Soap containing alkali if used will change the colour . 30-09-2021 Fouzia Mirza 53  

54. Mordant or Chrome Dyes :  Sodium or Potassium dichromate mordant is added in the dye bath.   This mordant along with dyes will penetrate into the fabric. These are used to dye wool and also for printing cotton. These are fast to light, washing and perspiration.   Developed Dyes :  This process requires a base to be dyed on the goods. This is followed by a   diazotizing process, whereby the dye is chemically changed and treated with a fresh set of chemicals, called developers, that form the completed dye. Developed dyes are fairly fast to washing because they have been literally built into the fibre . 28-09-2021 Fouzia Mirza 54

55. Sulphur Dyes :  Sulphur dyes, first made in 1879, are used for cotton and linen. Sulphur dyes are   insoluble in water and must be made soluble with the aid of caustic soda and sodium sulphide . These dyes are fast to washing, light and perspiration, but excessive chlorine will strip the colour .   Vat Dyes :  The first vat dye was an Indigo created in 1879. Vat dyes are the fastest dyes for cotton,   linen and rayon. Vat dyes are resistant to light, acids, alkali as well as to oxidizing bleaches. Vat dyes are insoluble pigments, but are made soluble in water by the use of a strong reducing agent, such as hydrosulphite developed in the alkali sodium hydroxide. The fabric is immersed in this solution. Subsequent exposure to air or immersion in an oxidizing bath ( bichromate ) restores the dye to its insoluble form as a part of the fibre 28-09-2021 Fouzia Mirza 55  

56. Reactive Dyes :  Reactive dyes were developed in 1957. These dyes react with fibre molecules to   form a chemical compound. These dyes were first designed for cellulose fibres , now available for wool, silk, nylon, acrylics and blends of these fibres . Advantages of reactive dyes are their excellent fastness to light and washing. They give very deep and brilliant colours .   Pigment Dyes :  Pigment dyes are not true dyes because they have no affinity for the fibre and if   applied and held to the fabric with resins, which are then cured at high temperature. The colours , confined to light shades, bright colours , such as metallic colours as gold are usually applied to cotton cloth but are also used in fabrics of wool and manmade fibres . 28-09-2021 Fouzia Mirza 56  

57. Optical Brighteners ( Colourless Dyes) :  These so-called dyes are also called fluorescent whiteners   or optical brighteners. The whiteness is really caused by absorption of ultraviolet light and reflection of visible blue light. Optical brighteners are available for cotton, acrylics, wool, acetate and nylon. They may be applied during bleaching, before resin finishing or with the resin. 28-09-2021 Fouzia Mirza 57

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67. The End Questionaries' 28-09-2021 Fouzia Mirza 67