Describe polyester dyeing process

Polyester

Polyester is a special type of polymer that contains the ester functional group in the main chain. It is a specific material, it refers to a type called polyethylene terephthalate (PET). It contains naturally occurring chemicals such as tree cuttings, as well as synthetics such as polybutyrate. Natural polyesters and a few synthetics are biodegradable, but most synthetic polyesters are not. Polyester material is widely used in clothing.

It is sometimes combined with natural fibers to create a fabric with blended properties. Cotton-polyester blends must be strong, wrinkle, and tear-resistant and reduce shrinkage. Man-made or synthetic fibers using polyester have higher water, wind, and environmental resistance than fibers obtained from plants. These are less fire-resistant and can melt when ignited.

Polyester dyeing process

In the polyester dyeing process, scattered dyed polyester fibers can be considered as a dye transfer process from liquid solvents like water to solid organic solvents like fiber.

When dyeing polyester, the scattered dyes are added to the water with a surface-activating agent for an aqueous dispersion. The invisibility of scattered pigments enables them to give up dye alcohols because they are more numerous than organic fibers than inorganic dyed alcohols. With the application of pigment heat (130 to 135 °C), alcohol increases the strength of the pigment molecule and accelerates the dyeing color of polyester fibers. Heating the pigment alcohol causes some amount of polyester fiber to swell and helps the dye to enter the polyester polymer system.

Thus the dye molecule takes place in the amorphous regions of the polyester fiber. Once the polyester has taken place in the polymer system, the dye molecules are held by the hydrogen bond and the van der Waals force.

The dye is taken in the following simultaneous steps: Isolation of individual molecules into the water to disperse the dye at a solid level. This expansion depends on the dispersion and solubility of the dyestuff and is aided by the presence of dispersing agents and rising temperatures.

Synthesis of dissolved dyes from polyester surface solutions. This dyestuff addition to the polyester surface is influenced by the solubility of the dye bath dyes and the polyester fiber. The splitting of the assorted dye from the surface of the fiber inside the fibrous material towards the center. Under normal circumstances, the rate of absorption is always higher than the rate of spread. And it’s a step in managing polyester dyeing.

Recipe for polyester dyeing-

Dyestuff – 2% (20-30g/liter) on the weight of the material

Carrier – 12 to 15g/liter

Dispersing Agent – 2 to 3g/liter

Acetic Acid – (Adding till pH-4)

Material: Liquor Ratio – 1:20

Temp – 130 °C

Time – 1hour to 1.5 hour

Polyester dyeing graph