Classification of acid dyes
2022-05-20
Acid dyes refer to containing acidic groups in dye molecules, also known as anionic dyes, which can be combined with amino groups in protein fiber molecules by ionic bonds, and are suitable for acidic, weak acid or neutral conditions. Dye is generally a compound that has its own color and can give other substances a bright and firm color in a molecular state or a dispersed state. Acid dyes are classified into strong acid, weak acid, acid medium and acid complex dyes according to their chemical structure and dyeing conditions.
1. Strong acid dyes
One of the earliest developed acid dyes requires dyeing in a strong acid dye bath. Its molecular structure is simple, its molecular weight is low, it contains sulfonic acid or carboxyl groups, and it has little affinity for wool. It is uniform, so it is also called acid level dyeing dye, but the color is not deep, the washing fastness is poor, and the wool is damaged during dyeing, and the dyed wool feels poor.
2. Weak acid dyes
In strong acid dyes, weak acid dyes are generated by increasing the molecular weight, introducing groups such as arylsulfone groups, or introducing long carbon chains. The molecular structure is more complex, and the affinity for wool is large. It can dye wool in weakly acidic medium without damage to wool.
3. Acid Mordant
Acid dyes that form metal complexes on fabrics after treatment with certain metal salts (such as chromium salts, copper salts, etc.) as mordant. Mordant procedures are more complicated, but dyes with better performance such as light fastness, washing fastness and rubbing fastness can be obtained.
4. Acid complex dyes
It is formed by complexing some acid dyes with metals such as chromium and cobalt. It is soluble in water, and its dyeing products have excellent lightfastness and lightfastness. Its dye parent is similar to the acid mordant dye, but when preparing the dye, the metal atom has been introduced into the azo dye molecule, and the ratio of the metal atom to the dye molecule is 1:1, so it is also called 1:1 metal complex dye. No further mordant treatment is required for staining.
Another type of acidic complex dyes do not contain sulfonic acid groups, but contain hydrophilic groups such as sulfonamido groups. The ratio of metal atoms to dye molecules in the molecule is 1:2, so it is also called 1:2 metal complex dyes. It is dyed in neutral or weak acid medium, so it is called neutral dye.
1. Strong acid dyes
One of the earliest developed acid dyes requires dyeing in a strong acid dye bath. Its molecular structure is simple, its molecular weight is low, it contains sulfonic acid or carboxyl groups, and it has little affinity for wool. It is uniform, so it is also called acid level dyeing dye, but the color is not deep, the washing fastness is poor, and the wool is damaged during dyeing, and the dyed wool feels poor.
2. Weak acid dyes
In strong acid dyes, weak acid dyes are generated by increasing the molecular weight, introducing groups such as arylsulfone groups, or introducing long carbon chains. The molecular structure is more complex, and the affinity for wool is large. It can dye wool in weakly acidic medium without damage to wool.
3. Acid Mordant
Acid dyes that form metal complexes on fabrics after treatment with certain metal salts (such as chromium salts, copper salts, etc.) as mordant. Mordant procedures are more complicated, but dyes with better performance such as light fastness, washing fastness and rubbing fastness can be obtained.
4. Acid complex dyes
It is formed by complexing some acid dyes with metals such as chromium and cobalt. It is soluble in water, and its dyeing products have excellent lightfastness and lightfastness. Its dye parent is similar to the acid mordant dye, but when preparing the dye, the metal atom has been introduced into the azo dye molecule, and the ratio of the metal atom to the dye molecule is 1:1, so it is also called 1:1 metal complex dye. No further mordant treatment is required for staining.
Another type of acidic complex dyes do not contain sulfonic acid groups, but contain hydrophilic groups such as sulfonamido groups. The ratio of metal atoms to dye molecules in the molecule is 1:2, so it is also called 1:2 metal complex dyes. It is dyed in neutral or weak acid medium, so it is called neutral dye.
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