Direct Scarlet 4BE / Congo Red

>Physicochemical Properties of  Direct Scarlet 4BE

Direct Scarlet 4BE  is yellow-red when soluble in water, orange when soluble in alcohol, and very slightly soluble in acetone, resulting in a clear bright red solution. Almost insoluble in ether.

> Specification of  Direct Dyes

Direct Scarlet 4BE are dyes that can be heated and boiled in neutral and weak bond phase medium without the help of mordants. Direct dyes are formed by the hydrogen bonding van der Waals force between direct dyes and cotton fibers.Direct dyes have water-soluble groups such as sulfonic acid groups (-SO3H) or carboxyl groups (-COOH) and their molecular structures are arranged in a linear shape. The aromatic ring structures are in the same plane, so direct dyes have a greater affinity for cellulose fibers. They can be dyed directly in a neutral medium and can be dyed as long as the dye is dissolved in water. For direct dyes with poor solubility, soda ash can be added to help dissolve. Direct dyes are not resistant to hard water. Most of them can combine with calcium and magnesium ions to form insoluble precipitates, causing stains on dyed fabrics. Therefore, direct dyes must be dissolved in soft water. If the hardness of the dyeing water used in production is high, soda ash or sodium hexametaphosphate can be added, which will not only help dissolve the dye but also soften the water.

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