Downloaded 33 times
Uploaded byVasanth Kumar
Mercerisation
Mercerization is a treatment of cotton yarn or fabric with a strong caustic soda solution that improves several qualities of the cotton. It increases luster and dye affinity, improves strength and stability, and results in smoother, rounder fibers. The process involves immersing cotton in a high concentration sodium hydroxide solution under tension control and then washing to neutralize the fabric. This summarizes the key points about mercerization from the provided document.
In this document
Powered by AI
Introduction to Mercerisation and its inventor, John Mercer. It is a treatment of cotton with caustic solution applied to yarn or fabric.
Enhancements from mercerisation: increased lustre, dye affinity, breaking strength (up to 20%), and dimensional stability. Suggested times to mercerise include greige and after bleaching.
Changes in cotton post-mercerisation: fiber structure, shrinkage properties, and uniformity. Machines used include yarn and continuous mercerising machines.
Details of the chain mercerising process: alkali impregnation, temperature, timing, washing, and final steps leading to mercerised fabric.
Overview of stenter units used in the mercerisation process, along with the limitations regarding fabric widths and space requirements.
Description and advantages of chainless mercerising machines, including space efficiency and ability to manage various fabric widths without distortion.
Introduction to pad-less chainless mercerisation focused on tension application, essential process sequence including impregnating and washing.
Explanation of dyeing methods, including stock and skein dyeing, with a focus on how color is applied to textiles using various dyeing and printing techniques.
More Related Content
Mercerisation
- 1.
- 2. About Mercerisation • Mercerizationis the treatment of cotton with a strong caustic solution. • This is performed on yarn or fabric, both woven and knits. Tension may or may not be used. Inventor John Mercer
- 3. Purpose • Lustre isincreased • Improves absorption, increase in dye affinity and yield • Improves breaking strength (improved up to 20%) • Improves dimensional stability • Improves chemical reactivity • Improves fabric smoothness • Covers immature cotton fibers
- 4. When to Mercerize •InGreige •Any step during preparation •After bleaching
- 5. Observable Changes or Propertiesof Mercerised Cotton • Deconvolution • Lumen disappears • Fibers become rounder, smoother, and more uniform • When cotton is mercerised slack (without tension), it shrinks and shows good elastic properties
- 6.
- 7.
- 8. The mercerisation process •NaOH Conc. : 18 to 22% (55o to 65 o Tw) • Time of contact : 60 to 75 seconds • Temp :27o C • Shrinkage : Controlled by stenter frame by stretching back to original width Caustic concentration – Lower- Less luster Time < 30 sec. Incomplete mercerization
- 9. • Yarn stage –yarn-mercerisingmachine • Fabric (continuous mercerisation process) –chain mercerisation machine –chainless mercerizing machine –chainless-padless continuous mercerising machine Machines used
- 10. Fixed Roller Movable Roller Perforatedpipe for spraying alkali/wash water Pointer and scale to set yarn tension A batch of hank yarn Tray Rubber Squeezer Roller
- 11. Mercerisation of Cotton Fabric •1. Chain mercerising machine – here the cloth is first allowed to shrink in the caustic soda solution and subsequently it is stretched. • 2. Chainless mercerising machine – in this case tension is applied to the fabric during alkali impregnation itself, so the fabric is not allowed to shrink. • 3. Pad-less chainless mercerising machine
- 12. Chain Mercerising Process 1. Firstalkali impregnation mangle (alkali concentration = 35-45° Tw; temp 40° C; time 60-75 sec) 2. Second alkali impregnation mangle (alkali concentration = 55-65° Tw; temp 27° C; time 60-75 sec) 3. Stenter (Stretching and washing unit) 4. Recuperator (Steam treatment to wash off residual alkali)
- 13. A Schematic Representationof the Chain Mercerising Process 1. First alkali impregnation mangle (alkali concentration = 35-45° Tw; temp 40° C; time 60-75 sec) 2. Second alkali impregnation mangle (alkali concentration = 55-65° Tw; temp 27° C; time 60-75 sec) 3. Stenter (Stretching and washing unit) 4. Recuperator (Steam treatment to wash off residual alkali) 5. Hot water wash 6. Souring (with dilute mineral acid) 7. Cold water wash 8. Mercerised fabric 3 5 6 874 GREY FABRIC 1 32
- 14. Chain Mercerising Process 5.Hot water wash 6. Souring (with dilute mineral acid) 7. Cold water wash 8. Mercerised fabric
- 15. Stenter – Stretchingand Washing Unit Fabric stretch zone in stenter Fabric counter - current wash zone Merceris ed, washed fabric WATER Flow Fabric Movement Chain I Chain II Clips Clips A basic diagram of a stenter unit in a chain mercerising machine (only some clips are shown)
- 16. Disadvantages of theChain Mercerising • Only certain widths of fabric limited to the stenter width can be used. • The stenter unit is very long and occupies a large amount of space.
- 17. Chainless Mercerising Machine • Impregnatingunit • Expanders or stretching rollers • Recuperator • Neutralising and washing unit • The functions of units (a), (c) and (d) and the conditions of mercerisation are the same as those for the chain mercerising machine. Only the stretching process (b) is different in this case.
- 19. Advantages of theChainless Mercerisation Machine • The floor space required is less compared to chain mercerizing. • Lightweight fabric can be mercerised easily. (This is difficult in a chain mercerising machine.) • There is no difficulty in mercerising cloths of different widths. • No distortion of material takes place. So checked fabrics can be processed on this machine without distortion of the design. • Two or three superimposed fabric pieces
- 20. Pad-less Chainless Mercerisation • Itis designed to mercerise fabric under tension • it does not require the use of the following units. –1) Impregnating mangles –2) Chain system (stenter)
- 21.
- 22. Important Process Sequence • ImpregnatingSection • Washing • Recuperator
- 23. DYEING • The applicationof color to the whole body of a textile material with some degree of fastness. There are two ways of adding colour to a textile substrate – Dyeing Dyeing completely covers the textile with colour --Printing. adds colour to the fabric surface in discrete or distinct places.
- 24. Materials Dyed • Fibers –Stock dyeing – Dope dyeing • Yarns – Skein dyeing – Package dyeing – Beam dyeing
- 25. Materials Dyed • Fabrics –Piece dyeing – Printing • Roller –application, resist, discharge • Flat Screen • Rotary – Tie Dyeing • Garments – Garment dyeing
- 26. Material used • Dyesand Pigments –The substances used to colour textiles can be classified as dyes or pigments, the differences between which are listed in the table below.
- 27.