Textile Desizing process | Classification | Advantages | Disadvantages

textile desizing process- pre treatment in dyeing


The objective of Desizing:

Desizing is the process in the wet processing or pre-dyeing did after the singeing process. During the weaving process, the size paste in form of starch, etc is applied to the yarn, so that it can withstand stress and strain during the weaving on the loom. If the same size paste remains on the grey fabric it will be really difficult to dye the fabric and hence in desizing process, the size is removed from grey fabric so that it should get uniform dyeing and finishing in further processing.

Classification of Desizing:

Classification of Textile Desizing process

Rot Steeping:

  • Rot steeping is the oldest and cheapest method where no special chemical is used.
  • The fabric is passed through warm water at a 40-degree celsius in padding mangle where the cloth is squeezed to about 100 percent expression.
  • The fabric is then allowed to stand for 24 hours the microorganisms naturally present in the water multiply and secret hydrolytic enzyme sizing through the water-soluble product.
  • The fabric used is washed to remove these products.

Advantages

  • Rot steeping is the cheapest method.
  • No Chemicals are required.
  • No special equipment is required.

Disadvantages

  • Large floor space is required.
  • The process is slow.
  • No control over the process.
  • Mildew may attack the cloth during the desizing and cause stains on the fabric.

Acid Desizing

  • Dilute sulphuric acid or hydrochloric acid from 0.25% to 1% is used to hydrolyze the starch from the sized fabric
  • The cloth is impregnated with a dilute acid solution in the padding mangle and then stores for 8 to 10 hours in a concrete Jet Alternatively the acid-treated fabric is bagged wet on a roller which is covered with the sheet of polythene and kept for 1 to 3 hours The fabric can also be stored at  60 degree Celsius to shorten time but if the concentration goes about 2% the degradation of fabric takes place.

Advantages:

  • Acid desizing is an economical process
  • The process is effective and gives fairly uniform desizing as it is a chemical-based process.
  • It doesn't require a specific condition of PH and temperature it is a quicker process than rot steeping

Disadvantages

  • The main disadvantage is that the mineral acid is harmful to cellulose fiber if proper care is not taken especially during the storage period.

Enzyme Desizing

  • Specific enzymes are used to liquefy the starch and make them soluble.
  • Desizing enzymes are animal or vegetable products.
  • Enzyme desizing is very rapid and thorough the method of desizing provided that the proper condition of temperature and pH are maintained.
  • In continuous desizing, the fabric is passed through hot water and then through 0.52 0.25% molt extract solution keep add 50 to 60 degree Celsius
  • The pre impregnation to hot water prevents cooling of enzyme solution.
  • The impregnated cloth is then taken over the guide roller and allowed to fall on a winch with a spoofing bottom where the cloth accumulates and assumes a very slope.
  • The length of the slope is such that the cloth gets dwell time of about 5 minutes for the desizing action.
  • Fabric is then taken to the washing machine where repeatable washing of the fabric is done.

Advantages

  • The time required for the sizing is less Continuous process so greater production can be achieved
  • Loosely constructed fabrics can be desized.
  • No chance of cellulose hydraulic which happens in acid sizing.
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1 Comments

  1. As a Textile Engineer i want to say Enzyme Desizing is better for greater production.
    Very informative article. Thank You

    ReplyDelete