Question

Which of the following Dyes are used for printing of polyester?

• A. Disperse Dyes
• B. Reactive Dyes
• C. Direct Dyes
• D. Acid Dyes

Hint:

Disperse dyes are the primary dye class used for polyester because they can diffuse into the hydrophobic fiber at high temperatures.

Answer 1

The Correct Option is A

Step 1: Understanding Polyester Fiber: Polyester is a hydrophobic, synthetic fiber with a relatively closed structure. It lacks the ionic or highly polar groups found in natural fibers like cotton or wool.
Step 2: Dye Classes and Fiber Affinity: Disperse Dyes: Disperse dyes are non-ionic dyes that are finely dispersed in water. They are applied to hydrophobic fibers like polyester in a high-temperature dyeing process (or printing process) where the fiber swells, allowing the dye to diffuse into the fiber. The dye remains within the fiber due to hydrophobic interactions. Reactive Dyes: Reactive dyes form covalent bonds with the fiber. They are primarily used for cellulosic fibers (cotton, rayon) and sometimes for wool and nylon, but not for polyester. Direct Dyes: Direct dyes are water-soluble, anionic dyes that have an affinity for cellulosic fibers. They are not effective on polyester. Acid Dyes: Acid dyes are anionic dyes used primarily for protein fibers (wool, silk) and nylon. They are not effective on polyester.