Textile Dyeing and Dyes have been classified into different groups, each group is suitable for certain types of textile substrates. Some commonly used dyes, For example, the most commonly used type of dye for cotton, polyester, and acrylic are reactive dyes, disperse dyes, and basic dyes, respectively.
Textile Dyeing can be classified into two main types:
- Exhaust dyeing
- Pad dyeing
Exhaust Dyeing – Textile Dyeing
In exhaust dyeing, a finite amount of textile materials (in the shape of fibers, yarn, or fabric) is placed within the dye liquor and remains in its contact throughout the dyeing time. During which the dye molecules gradually move (or exhaust) from the liquor toward the material. For absorption and fixation within the textile material. With the assistance of dyeing temperature, liquor agitation, pH, or auxiliaries like electrolytes, alkalis as well as leveling agents, or retarding agents, etc.
The liquor to the material ratio (L: R) is additionally crucial to think about exhaust dyeing. The ratio between the quantity of liquor and therefore the weight of textile material dyed therein liquor during a batch. Total dyeing time required in exhaust dyeing depends on several factors including depth of shade. Sort of dyestuff, nature of textile material, and sort of dyeing machine.
Phases In Exhaust Dyeing
The overall phases in exhaust dyeing include the following:
- Disaggregation of dye particles in solution or dispersion
- Exhaustion or movement of the dye molecules from the answer/dispersion towards the textile substrate
- Adsorption of the dye molecules on the surface of the textile substrate
- Absorption, penetration or diffusion of the dye molecules into the fibers of the textile substrate
- Fixation of the diffused dye within the fibers through chemical bonding or by another mechanism
Pad Dyeing – Textile Dyeing
In the pad dyeing method, an endless batch of cloth. In open width passes through an impregnator (or padding trough) containing dye liquor, followed by a passage between a pair of squeeze rollers. The pressure of the squeeze rollers is often adjusted to get a desired wet pick-up. for instance. A wet pick-up of 100% would end in fabric twice its original dry weight, after the impregnation and squeezing.
The concentration of the dye within the padding tough and therefore the wet pick influences the ultimate depth of color obtained on the material. After passing through the squeeze rollers. By the sort of means including as well as making a batch of cloth. Keep rolling the batch for a selected period (pad-batch dyeing method). Passing the material through a drying and fixation unit (pad-dry-fix dyeing method). The material through a drying and steaming unit (pad-dry-steam dyeing method); passing the material through a steaming unit (pad-steam dyeing method).
After Dyeing Process
After both the exhaust and pad dyeing methods. The dyed fabric is typically subjected to washing as well as rinsing steps to get rid of any unfixed dye from the material. The selection of a specific dyeing method depends on several factors including the shape of textile material (fiber, yarn, knitted or woven fabric), availability of suitable equipment within the mill, and a batch size of the textile material.