Procedure of Scouring Process | Chemicals Used in Scouring Process

Theory of Scouring:
Natural fibers contain oils, fats, waxes, minerals, leafy matter and motes as impurities that interfere with dyeing and finishing. Synthetic fibers contain producer spin finishes, coning oils and/or knitting oils. Mill grease used t o lubricate processing equipment mill dirt, temporary fabric markings and the like may contaminate fabrics as they are being produced. The process of removing these impurities is called Scouring. Even though these impurities are not soluble in water, they can be removed by Extraction, dissolving the impurities in organic solvents, Emulsification, forming stable suspensions of the impurities in water and Saponification, Converting the contaminates into water soluble components.

 Procedure of Scouring Process:
The main processes occurring during scouring are:

1. Saponification of fats into water-soluble soap and water-miscible glycerin under alkaline conditions,
2. Hydrolysis of proteins into water-soluble degradation products,
3. Dissolution of hydrolysis to ammonia of simpler amino compounds,
4. Conversion of pectose and pectin into their soluble salts,
5. Dissolution of mineral matter,
6. Emulsification of unsaponifiable oils and waxes, and
7. Removal of dirt particles from the kier liquor by the detergent present therein

A typical mixture of chemicals useful for cleaning fabrics is shown in Table.

Chemical


Use
Caustic (NaOH)
Neutralize acidic materials, saponify    glycerides (Waxes and Oils), and solubilize silicate.
Sodium Silicate
Penetrate and break down lignins in motes.
Surfactant
Reduces surface tension and minimize interfacial tensions.
Detergent
Emulsify oils, fats, and waxes; remove oil – borne stains; suspend materials after they have been removed.
Chelating (Sequestering) agent
Deactivate metal ions.
Builder (Salt)
Cause detergents to become increasingly effective.
Solvent
Assist emulsification by dissolving oily materials.

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