1. 1. Chemical Processing of Textiles:- I (Pre-Treatments) Aravin Prince Periyasamy Dept of Textiles, DKTE TEI, Ichalkaranji, MH, India aravinprince@gmail.com color.ppt

2. 2. Agenda………. Intro - Pre-Treatment s Process Sequence Grey inspection Desizing Scouring Bleaching

3. 3.  Removal of impurities by physical and chemical method.3 Preparation is the process of preparing fibers yarn, or fabric for subsequent steps such as Dyeing, Printing, Finishing and or special processes for apparel and non apparel end Uses. Preparation Definition

4. 4.  Uniform residual moisture content.4 Minimum fiber damage Uniform swollen fibers to transport dyes and chemicals Uniform standard of whiteness Uniform extraction of impurities Preparation Objective The aim of above process to produce a substrate that has…

5. 5.  Examples Singeing, Desizing, Scouring, Bleaching, Heat-setting, Mercerization and etc.5 These processes ensure that textiles have the right physical and chemical properties to enable them to be coloured or finished. Preparation Process

6. 6. 67. 7. Grey Inspection8. 8.  Comparing these with specific requirements to determine conformity.8

Activities such as Measuring, Examining, Testing, Gauging, one or more characteristics.InspectionDefinition:

9. 9.  EPI, PPI, Width and Length of fabric Also in grey inspection following points are checked, Many of these faults can be corrected at grey stage before wet processing. Grey cloth from weaving have many faults ( Broken ends and picks, stains and etc) & GSM.9

10. 10.  Point Based10 Flow Based Types of Inspections 11. 11. Woven fabric inspection aravindXB_filestextiles

_CDAnimationsgrey inspection.mpg1112. 12. 1213. 13. Knitted Fabric Inspection1314. 14.  To control pill formation.14 To give clean and smooth

appearance to the fabric. To remove the projecting yarns and filaments from the surface of the fabricCropping And ShearingDefinitionShearing is the process of cutting projecting fibers and yarns to give smooth and clean appearance by rising knives and blades.Objects

15. 15. Shearing Machine Schematic1516. 16.  Fabric may be passed over 1.Heated plates or rolls 2.Fabric

moves directly into quench box16Singeing... Definition Singeing is defined as the process carried out for the purpose of removing the loose hairy fibres protruding from the surface of the cloth, thereby giving it a smooth, even and clean looking face.

17. 17. 17

18. 18. Before& After Singeing1819. 19. 1920. 20. Mechanism of Gas Singeing Singeing2021. 21. 2122. 22. Circular Singeing Machine2223. 23. 2324. 24. 2425. 25. Yarn Singeing2526. 26. Yarn Singeing2627. 27.  Evaluate the Pilling Test...27 By Visual method… Testing of

Singeing 28. 28. Desizing29. 29. 2930. 30.  The main ingredient in size paste is Starch. Water In To

remove the Size Ingredients from textile materials. Objects....... soluble Water Soluble30

31. 31. MdEethods of Desizing3132. 32. Rot Steeping3233. 33.  The cloth is impregnated with the dilute acid solution in a two-

bowl or three-bowl padding mangle and then stored for 4-6 hours in a closed concrete pit.33 A 0.25% - 0.5 % solution of the acid at room temperature. Dilute sulphuric acid or hydrochloric acid – hydrolyse.Acid Desizing

34. 34.  Excellent method (Safe, perfect removal of size, less energy, less pollution)34 Enzyme ( α- amylase). Enzymatic Desizing

35. 35. 3536. 36. Continuous Desizing3637. 37.  Oxidize the starch molecules.37Desizing with Oxidizing agents38. 38.  TEGAWA Scale38 Weight loss Testing of Desized Fabric 39. 39. Scouring40. 40.  Their presence leads to improper dyeing, printing and finishing

as it would be difficult for dyes and chemicals to go uniformly into the fibre structure.40 They are hydrophobic in nature. Natural impurities Oils, Fats, Waxes, Pectin, Protein, Seed Coat, Mineral Matters. Desizing Size Ingredients.

41. 41. Scouring of 100 % Cotton Recipe for kier boiling For kier boiling cotton desized goods the following chemicals and boiling conditions are used. Sodium hydroxide – 1.5 to 2% Sodium silicate – 1% Soap – 1% Detergent (Wetting agent) – 1% M:L Ratio – 1:5 pH – 10 to 11 Pressure – 1.5 to 2.0 kg/cm2 Time – 6 to 12 hours41

42. 42. Kier4243. 43. Scouring of 100 % cotton (Woven)43

44. 44. Closed Jigger44 CPT PRESENTATIONdyeingjigger bleaching.mpg

45. 45. Scouring of 100 % cotton (Winch) 1 – Winch 3 – Fabric rope 5 – Heating coils 7 – Rack 2 – Guide cylinder , 4 – Perforated separator 6 – Liquor45 CPT PRESENTATIONdyeingwinch bleaching.mpg

46. 46. Jet Dyeing Machine4647. 47. Scouring of Knitted fabric (Soft flow)47 CPT

PRESENTATIONdyeingsoft flow.mpg48. 48. Scouring (Semi – Cont )4849. 49. Scouring of Yarn (Package Dyeing Machine)4950. 50. Inside-out liquor flow in cheese dyeing Outside-in liquor flow in

cheese dyeing5051. 51. automatic cheese dyeing machineautomatic cheese

dyeing.MPG51 CPT PRESENTATIONdyeingpackage dyeing.mpg52. 52. Scouring of Coloured Woven Cotton Fabric Recipe Sodium

Carbonate – 1% Sodium silicate – 1% (Normal atmospheric condition) Soap – 1% pH – 10 to 11 Time – 4 to 6 Hrs Temperature – Boil52

53. 53. Scouring of Polyester / Cotton Blends Recipe Soda Ash - 0.5 to 1% Detergent - 0.2 to 0.5% Temperature - 100o C Time - 60-90 minutes.53

54. 54. Bleaching55. 55. Objects…..•Removal natural colouring.•Dark shade – No

bleaching.•Light shade / full white.•Printing of white background.•The natural colouring matter in cotton can bedestroyed by oxidation (oxidation bleach) or byreduction (reduction bleach) or by a combination ofboth. 55

56. 56. Oxidative Bleaching AgentsPeroxide system Chlorine systemHydrogen peroxide Bleaching powderSodium peroxideSodium per borate Sodium hypochloritePotassium permanganate Sodium ChloritePer acetic acid56

57. 57. Reductive Bleaching Agents Sulphur dioxide Sodium hydrosulphite Sulphoxylates Sodium bisulphite57

58. 58.  It is given a treatment with a solution of sodium bisulphite58 To free the material from any traces of residual chlorine Anti-chlor treatment To remove by neutralisation the last traces of alkalinity in the material ‘soured’ with dilute mineral acid (like 1 g/l HCl) Souring: Application of Hypochlorite Hypochlorite Bleaching

59. 59.  Under certain conditions particularly with regard to pH, hydrogen peroxide will liberate hydrogen and perhydroxyl ions in the following manner.59Hydrogen Peroxide (H2O2) Bleaching

60. 60.  Sodium silicate60 However, rapid decomposition of the unstable HO2 ions is not desirable, as the decomposition process will overtake the bleaching action. pH 10.5 – 11The need for a stabiliser:

On addition of caustic soda the concentration of decomposable HO2 ions increases, For Better H2O2 bleachingThe need for alkaline pH:

61. 61. 61 CPT PRESENTATIONdyeingjigger bleaching.mpg CPT PRESENTATIONdyeingwinch bleaching.mpg

62. 62. Continuous Scouring and Bleaching by J box62 CPT PRESENTATIONdyeingBruckner.mpg

63. 63. 6364. 64. BLEACHING – 3 MAIN STEPS Capacity: ca. 600 kg/h Wahing

off & Demineralization Bleaching (pad-steam) rinsing (incl. de-oiling) 1 65 °C 2 50 °C 100 °C 3 95 °C 50 °C 50 °C 50 °C 95 °C 60 °C 50 °C pH control Drain Feed Dosing Feed Drain Feed 3 l/kg 6 l/kg in counterflow Washing after bleaching pH-neutralization Hydroextraction Pad-Steam-Bleach Time: ca. 15 min Time: ca. 5 min Demineralization bleaching chemicals Impregnation with demineralization agent Impregnation with 64 Division_Textile06_Pretreat_Bleach.mpg

65. 65. Complete Process Cycle In A Continuous Processing A) Bleaching for RFD / Full-White Drying B) Cold pad batch dyeing C) Washing after dyeing Drying65

66. 66. Bleaching with Peracetic acidComposition:It is a very strong oxidizing agent and has stronger oxidation potential thanchlorine or chlorine dioxide.66

67. 67. Advantages Environmentally safe. Decomposes into acetic acid and oxygen Very suitable for bleaching nylon Bleached goods show higher brightness with less fibre damage. Disadvantage Concentrated solution (35-40%) dangerously explosive Expensive compared to H2O2 Stability is not as high as H2O267

68. 68. ….? 6869. 69. …Jaihind… 69