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:
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
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.
- 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
- pH should be neutral and Fabric should run continuously in the machine loaded with enzyme solution
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