In this process, the fabric is treated with some chemicals or other useful agents to make it qualitatively more better, for e.g. cotton is made sun protected by treating it with UV protecting agent.
Enzyme Washing
Enzyme Washing is a process used to treat dyed fabric or garments to give it a worn or aged appearance.
Cellulase enzymes are used, often on finished garments of cotton denim, to make the garment appear like it has been worn and washed repeatedly. Prior to the use of enzymes, similar effects were produced with acids and/or sand or stone washing where the garments were tumbled with pumice stones.
Cellulase enzymes are used, often on finished garments of cotton denim, to make the garment appear like it has been worn and washed repeatedly. Prior to the use of enzymes, similar effects were produced with acids and/or sand or stone washing where the garments were tumbled with pumice stones.
Sanforising
Sanforising allows to prevent the cotton from shrinking when washed. It is carried out by compressing the cotton to reduce its shrinking capacity .
Calendaring
Calendering consists of submitting the fabric to a high pressure between two cylinders at high temperature, which will give a bright and ironed aspect. There is a variant to calendering called honeycomb by which embossed patterns are engraved on the surface of the fabric.
Raising
Raising and sueding consist of cutting certain fibres on the surface of the fabric to give them a soft and velvety aspect. Raising is obtained by grating the fabric with metallic points, and sueding by the friction of sandpaper.
Mercerising
Mercerisation is one of the most important processes of finishing cotton materials. It imports gloss to the fibre, increases its hygroscopicity, strength and improves its dye affinity.
The mercerising process consists in treatment of cellulosic materials with concentrated solutions of caustic soda at a temperature of 15 to 18°C. Mercerised cellulose is hydrated cellulose, i.e., a product which from the chemical point of view, is identical to the original cellulose, but differing from it in physical properties. This method was patented in 1850 by the English calico printer John Mercer and hence forth this process has been called as mercerisation.Under the action of concentrated alkaline solutions chemical, physico-chemical and structural modifications of cellulose take place. Chemical reactions lead to the formations of alkali cellulose, physical reactions, to intensive swelling of fibres and structural reactions, to a change in the arrangement of units in the cellulose macromolecule.
Concentrated solutions of caustic soda cause considerable swelling of cotton fibre, the changes in cellulose physical properties being irreversible. When the fibre swells, its volume undergoes considerable changes; at maximum water absorption, the cross section of cotton fibre is increased by 40 to 50% with inconsiderable increase in length (about 1 to 2%).
The size of pores in the fibrous,material is considerably increased.
The main factors influencing the factors of selling are temperature of treatment, the concentration of the alkali in the solution and additions made to the solution. Cellulose swelling in an alkaline solution increases with a drop of temperature.
Alkali concentration is also of great importance for the cellulose swelling. The greatest swelling of cotton cellulose is observed at alkali concentrations characterized by an appearance of an X-ray pattern of an alkali cellulose.
The mercerising process consists in treatment of cellulosic materials with concentrated solutions of caustic soda at a temperature of 15 to 18°C. Mercerised cellulose is hydrated cellulose, i.e., a product which from the chemical point of view, is identical to the original cellulose, but differing from it in physical properties. This method was patented in 1850 by the English calico printer John Mercer and hence forth this process has been called as mercerisation.Under the action of concentrated alkaline solutions chemical, physico-chemical and structural modifications of cellulose take place. Chemical reactions lead to the formations of alkali cellulose, physical reactions, to intensive swelling of fibres and structural reactions, to a change in the arrangement of units in the cellulose macromolecule.
Concentrated solutions of caustic soda cause considerable swelling of cotton fibre, the changes in cellulose physical properties being irreversible. When the fibre swells, its volume undergoes considerable changes; at maximum water absorption, the cross section of cotton fibre is increased by 40 to 50% with inconsiderable increase in length (about 1 to 2%).
The size of pores in the fibrous,material is considerably increased.
The main factors influencing the factors of selling are temperature of treatment, the concentration of the alkali in the solution and additions made to the solution. Cellulose swelling in an alkaline solution increases with a drop of temperature.
Alkali concentration is also of great importance for the cellulose swelling. The greatest swelling of cotton cellulose is observed at alkali concentrations characterized by an appearance of an X-ray pattern of an alkali cellulose.
Bleaching
The fabrics are bleached to make it more whiter and lighter in this process.
Typically, hydrogen peroxide, sodium chlorite, sodium hypochlorite are used for bleaching. Hydrogen peroxide bleaching is becoming a mainstream, taking environmental problems into consideration. In general, reduction bleaching is not suitable for cotton.
Typically, hydrogen peroxide, sodium chlorite, sodium hypochlorite are used for bleaching. Hydrogen peroxide bleaching is becoming a mainstream, taking environmental problems into consideration. In general, reduction bleaching is not suitable for cotton.
Scouring
The cleaning part of the fabrics are involved in this process.
To remove pectic substances and cotton wax contained in cotton woven fabrics,the use of caustic soda (NaOH), strong alkali, is the most effective. The caustic soda has the effects of not only converting water-insoluble pectose contained in pectic substances into water-soluble pectic acid soda, but also of hydrolyzing (saponifying) cotton wax. However, a single use of the caustic soda does not provide enough penetration, emulsion, washing, and scouring powers, and so a surfactant is generally used together.
A chelating agent may also be used together to prevent insolubilization caused by calcium and magnesium
Also, a method of scouring with an enzyme instead of with the caustic soda is being considered in recent years.In this case, protopectinase is used for degrading pectin, and lipase and the like are used for degrading oil.
Desizing
This process involves removing the size material from warp yarns in woven fabrics.
Desizing, irrespective of what the desizing agent is, involves impregnation of the fabric with the desizing agent, allowing the desizing agent to degrade or solubilise the size material, and finally to wash out the degradation products. The major desizing processes are:
Desizing, irrespective of what the desizing agent is, involves impregnation of the fabric with the desizing agent, allowing the desizing agent to degrade or solubilise the size material, and finally to wash out the degradation products. The major desizing processes are:
- Enzymatic desizing of starches on cotton fabrics
- Oxidative desizing
- Acid desizing
- Removal of water-soluble sizes
Singeing
Singeing is a finishing method for smoothing surfaces of fabrics by burning and removing fuzz thereon, and visualizing fabric textures.
A gas-singeing machine is normally employed. The gas-singeing machine is typically equipped with four burners, and is capable of singeing one or both surfaces of the fabrics. A water-cooled roller is provided at a location opposite to the burners, thereby enabling singeing to be performed without undermining the strength of even thin fabrics. It is important to set a drain temperature of the water-cooled roller in a range of 50 to 55 C.
Cautions are required because a dew-point is generated when the water-cooled roller is cooled down too much, and results in increased amount of remaining fuzz or adhered carbon. The fabric feed speed is preferably set at around 100 to 150m/minute.
A gas-singeing machine is normally employed. The gas-singeing machine is typically equipped with four burners, and is capable of singeing one or both surfaces of the fabrics. A water-cooled roller is provided at a location opposite to the burners, thereby enabling singeing to be performed without undermining the strength of even thin fabrics. It is important to set a drain temperature of the water-cooled roller in a range of 50 to 55 C.
Cautions are required because a dew-point is generated when the water-cooled roller is cooled down too much, and results in increased amount of remaining fuzz or adhered carbon. The fabric feed speed is preferably set at around 100 to 150m/minute.
Overview of Textile Processing
Textile processing is one of the important industries related with textile manufacturing operations. This industry has a long history that begins with "Indigo dyeing" a natural color, derived from a plant.
Once the process of coloring textiles was considered as an art. According to ones creativity and imagination on those days numerous techniques were evolved in coloring different materials such as cotton, bamboo, jute, earthen-ware and even mortar walls. Slowly this technique was evolved in to a science and so many artificial coloring matters called 'dyestuffs' had started coming in to existence.
This evolution of coloring matters in to synthetic dyestuff and the application techniques on various textile materials are all put together is called 'Textile Processing'.
Textile processing is a general term that covers right from singeing(protruding fiber removal) to finishing and printing of fabric.
Once the process of coloring textiles was considered as an art. According to ones creativity and imagination on those days numerous techniques were evolved in coloring different materials such as cotton, bamboo, jute, earthen-ware and even mortar walls. Slowly this technique was evolved in to a science and so many artificial coloring matters called 'dyestuffs' had started coming in to existence.
This evolution of coloring matters in to synthetic dyestuff and the application techniques on various textile materials are all put together is called 'Textile Processing'.
Textile processing is a general term that covers right from singeing(protruding fiber removal) to finishing and printing of fabric.
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