We know that dyes and chemicals are the main factor for producing color in yarn of fabric. Different types of chemicals are used during dyeing. In different stages of dyeing processing, various chemicals are used. Every chemical have their own characteristics and they are used in different stages of wet processing.
List of Chemical auxiliaries used in wet processing unit and their function is given bellow:
- Acid: Acid is used to control PH. Acid decrease the pH of the solution. If PH 1-7 then it is called Acidic solution.
- Basic: Basic is used for increase the PH of the solution. PH range of basic is 7-14. This also used as scouring agent.
- Peroxide Killer: This chemical is used to kill per oxide which is remaining in the material. Peroxide is harmful for the material. A test is carried out to measure the amount of peroxide present in the solution.
- Bleaching Agent: Bleaching is carried out before dyeing or printing operation. Better absorption of dyes depends on better bleaching. Absorbency test is carried out to test the bleaching performance. Absorbency time should lie under 5 second. It is used for removing natural color from the grey yarn or fabric.
- Salt/Electrolyte: Salt is used as electrolyte. Salt increase the exhaustion rate of the dyeing process. Different types of salt are used for different shade. The amount of salt used depends on the shade % of the material.
- Scouring Agent: Scouring agent is used to remove fat, waxes, fragments of cotton etc.
- Antifoaming Agent: Foam is formed during bleaching and dyeing process. Anti foaming agent is used to resist foam formation. If foam formed it reduces the dyeing uptake %.
- Sequestering Agent: This agent is used to remove hardness of water.
- Dispersing Agent: This agent is used for disperse dyes. We know, disperse dye is insoluble in water and dye present in disperse form. By applying this agent dye molecule breaks and become soluble in the solution.
- Neutralization Agent: This agent is used to neutral the PH of the solution.
- Wash/Soaping Agent: Soaping agent is used for washing. It needs to wash dyed material to remove unfix dye from the material. Dark material needs double wash. But light shade materials needs single wash, sometimes no wash is carried out for light shade. It also increases the reflecting properties.
- Softening Agent: This agent is used to increase softness of the material. This agent used as finishing material.
- Fixing Agent: This agent is used for fixing of dyestuff and also remove the unfix dye.
- Brightening Agent: This agent is used to increase the brightness of the material. This agent increases the reflecting property of the material. Standard reflecting value is 85%. But sometimes it is possible to increase it up to 95%. But it is risk because it needs high kier boiler temperature, which reduces the strength of material.
So, we should use the chemical auxiliaries according to their scope of use.