Sunday, 14 September 2014

Major Desizing Processes: The main desizing processes are given below:
Rot steeping
Acid steeping
Oxidative desizing
Enzymatic desizing

Rot steeping:   

                         In this process fabric is stored at 40-60 degree Celsius for overnight in water. It                         removes starch and water soluble impurities with natural reaction.

 Following are main drabacks associated with this  process:
                      
                           - It is time consuming process
                           - It is not certain that in the given duration, sizing material will remove or not.

Acid Steeping:

                           Here acid behave as hydrolysing agent. It reacts with bigger molecule and hydrolyze                  it to smaller molecules. For example starch, which is important ingredient of sizing                      recipe react with acid and  is hydrolyzed to glucose. In acid steeping, fabric is treated                  with sulphuric acid (0.5% to 1.0%) or Hydrochloric acid. The main drawback                              associated with this process is that the fabric get tendered or damaged if acid is                            remained in the treated fabric.

Oxidative desizing: 
                
                          Starch and other added impurties are hydrolysed through oxidation process.                                  Following oxidizing agesnts may be used for this purpose:

                           -Sodium hypochlorite: 2.0-5.0 g/l at room temperature at around pH 7.0
                           -Hydrogen peroxide: 3.0- 6.0 g/L  and 7-15 g/l Sodium hydroxide at 40 degree                             Celsius for 12-16 hours. 

Following are the drawbacks involved with this process:

                        
                            -It is a time consuming process
                            -In this process, bleaching effect is also produced which some time not                                          required.

Enzymatic desizing: 

                            Enzymatic desizing is carried out using amylase enzyme as the main                                            constituent of starch is amylose. Following recipe may be used for desizing
                            
                                       -0.5% to 2.0% Enzyme  on weight of fabric (OWF) in water                                                          -Require quantity of Common salt
                               - pH should be neutral and Fabric should run continuously in the machine                                          loaded with enzyme solution
    

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