Introduction to Textile wet Processing
Introduction:
* Textile wet processing is one of the key sectors of the textile industry.
* Wet processing of textiles consumes huge quantity of water and the quality of the process largely depends on the water quality thus water becoming the essential component of the process.
* The amount of water required for each depends on the type of material, type of process and the machine used.
water
Water – the essential component of life covering about 71% of earth’s surface.
General sources of water for textile industry
The general water sources for the textile wet processing industry may be from one of the following:
a) Surface water bodies like rivers, lakes, ponds, etc
b) Ground water
c) Public water supply systems.
Singeing
Singeing is the process for removing the hairs of fabrics or fibers. In singeing process, we use three technique to applied it. Such as, gas flame technique. At the end of this process, we will find, that the fabrics is smoother than before and the fabrics wet ability is increase. Fabric may be passed over
1. Heated plates or rolls
2. Fabric moves directly into quench box
Objects of Singeing
* To remove hairy fibres projecting on the surface of cloth and to smooth surface.
* Optical levelness of the dyeing and clean out lines of a printing design.
* To increase luster in the finished fabric.
* To prepare the fabric for next process.
Technique of singeing:
Gas flame:
The fabric passes over burning flame to burn the hairs of the fabric.
Roller:
The fabric is singed with or passed over heated rotary copper cylinders.
Hot plates:
The fabric is trough over the heated plates at speed (150/250 yards/minute).
Desizing
Desizing is done in order to remove the size from the warp yarns of the woven fabrics. Warp yarns are coated with sizing agents prior to weaving in order to reduce their frictional properties, decrease yarn breakages on the loom and improve weaving productivity by increasing weft insertion speeds.
Objects of Desizing:
* To remove the starch material from the fabric.
* To increase the absorbency power of the fabric.
* To increase the affinity of the fabric to the dyeing chemicals.
* To make the fabric suitable for the next process.
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 to 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.
Types of Scouring Treatments
* Scouring By Chemicals Means
* Bio scouring or scouring with Enzymes
The scouring operation was conventionally done in kier machines and hence the process was called kier boiling , but now a days the scouring is done mostly in the dyeing machines itself as a part of combined or single operation such as scouring and bleaching.
What happens during scouring?
I. Saponification of fats into water soluble soap and water miscible glycerin under alkaline conditions.
II. Hydrolysis of proteins into water soluble degradation products.
III. Dissolution of amino compounds.
IV. Solubilising of pectose and pectins by converting into soluble salts .
V. dissolution and extraction of mineral matter.
VI. Emulsification and solubilisation of natural oils and waxes.
VII. removal and dispersion of dirt particles and kitty by the action of alkali and detergent.
Bleaching
Bleaching is chemical treatment employed for the removal of natural coloring matter from the substrate. The source of natural color is organic compounds with conjugated double bonds.
The aim of bleaching
* Removal of colored impurities.
* Removal of the seed coats.
* Technically reliable & simple mode of operation.
* Low chemical & energy consumption.
* Increasing the degree of whiteness.
Dyeing
Dyeing is the process of adding color to textile products like fibers, yarns, and fabrics. Dyeing is normally done in a special solution containing dyes and particular chemical material.
Methods of Textile Dyeing
Color is applied to fabric by different methods of dyeing for different types of fiber and at different stages of the textile production process.
These methods include:
Direct dyeing
Stock dyeing
Top dyeing
Yarn dyeing
Piece dyeing
Dope dyeing
