In this article, we are going to learn about the dyeing process of acrylic yarn with basic dye. The process followed in the lab is described here as follows.
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Introduction
Basic dyes are also known as cationic dyes. This is a class of synthetic dyes that act as bases when made soluble in water, they form a cationic salt which can react with the anionic sites on the surface of the substance. It is suitable for acrylic yarn. Acrylic fibers may contain a variety of different anionic groups. Acrylic fibers are synthetic fibers made from a polymer. The polymer is formed by free-radical polymerization in an aqueous suspension. So colored cations of ionized dye are absorbed on the acrylic fiber surface. Absorbed dye cation diffuses in the interior of fiber at a particular temperature. Cations are attracted to and retained by the anionic sites in the fiber substance by strong electrostatic attraction forces.
Objectives
- Learn more about acrylic yarn.
- To know about basic dyestuff.
- To have an idea of the dyeing curve of acrylic yarn.
- To know about the recipe.
Recipe
Calculation
Now, freshwater needed = (120-Total chemicals) ml
Figure of Dyed Acrylic Yarn
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| Dyed Acrylic Yarn |
Dyeing Curve for Acrylic Dyeing
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| Acrylic Yarn Dyeing Curve |
Auxiliary Chemical Functions
Basic dyes: Basic dyes are cationic soluble salts of colored bases. Basic dyes are applied to a substrate with an anionic character, where electrostatic attractions are formed. Basic dyes are called cationic dyes because the chromophore in basic dye molecules contains a positive charge. The basic dyes react on the basic side of the isoelectric point. Basic dyes are salts, usually chlorides, in which the dyestuff is the basic or positive radical. It's a powerful coloring agent. It is applied to wool, silk, cotton, jute, and modified acrylic fibers.
Wetting agent: It accelerates the wettability of material in solution, thus helping the easy penetration of chemicals into the substrate. It reduces the surface tension of water to allow it to spread into drops onto a surface, increasing the spreading abilities of a liquid.
Acetic acid: Its function is to control pH in the process.
Sequestering agent: In the absence of a water-softening plant in an industry, it is also possible to reduce the unwanted interference of heavy metal ions during soaping or dyeing by a sequestering agent. A sequestering agent is a substance that suppresses the property or reaction of metal ions without the removal of that metal from the system. The most common sequestering agent is EDTA, known as ethylenediamine-tetra acetic acid.
Glauber's salt (Na2SO4.10H2O): This salt is used as an electrolyte. It reduces or extinguishes the charge on the fiber, to color fabric.
Sodium acetate (CH3COONa): It is a salt that acts as a leveling agent and a buffer to maintain the pH of 4.5 to 5 during the entire dyeing time. The addition of sodium acetate helps to keep the fiber soft and damage-free.