Classification of direct dyes:
Direct Dye can be classified into the following two parts
A) According to the application
B) According to chemical constitutions
Table of Contents
A) According to the application:
The direct dye can be divided into three categories based on the application method. E.g.
1. Class-A or self-leveling direct dyes
2. Class-B or salt controllable direct dyes
3. Class-C or temperature Controllable direct dyes
1. Classification of direct dyes-Class-A:
These types of dyes can migrate well from one place to another and their leveling capacity is high. They can dye unevenly on the fiber, but when re-boiled, the dye sticks evenly to the fabric. Labeling can be done without the help of anything extra and manually. This is called Self-leveling direct dye. The fastness of this dye is not very good.
2. Classification of direct dyes-Class-B:
The leveling capacity of this class of dyes is negligible, but the addition of salt increases the dyeing capacity of the dyes. If these dyes are not taken evenly in the first stage, then it is completely difficult to fix the inequality. Dyeing will not be right if the salt ratio is not right here. This class of dye is called Salt controllable dye as its leveling power is controlled by salt. However, if the salt ratio is correct, the dye is very good.
This dye has no leveling ability of its own. They are very sensitive to salt. It is not possible to control exhaustion by adding salt alone. In this case, dye exhaust is controlled by temperature. This is why this dye is called temperature controllable dye. Dyeing will not be correct if the temperature is not right. In this case, it is very difficult to do unequal dyeing first and then balanced dyeing. This is also a very good dye.
B) According to chemical constitutions:
The direct dye can be divided into four classes based on the chemical composition format. E.g.
1) Azo derivatives
2) Stilbene- derivatives
3) Thiazole- derivatives
4) Phthalocyanine derivatives
1. Classification of direct dyes-Az0 derivatives:
Most of the colors in this class are Sulfonatedazo compounds. These can be mono azo, diazo, tri azo, and poly azo.
2. Stilbene derivatives:
3. Thiazole derivatives:
Also available from various direct die thiazole groups.
Permuline is a very mature color in direct dye.
4. Phthalocyanine derivatives:
The latest class of Direct dye is based on Phthalocyanine.
Example: Durazol Blue 8G. It is a very bright greenish-blue with good light fastness but poor washing fastness.