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Acid Dyes

Acid dyes are named for their application under acidic conditions. Chemically, acid dyes are based on azo, anthraquinone, and triphenylmethane Cu-phthalocyanine systems, which are anionic and water-soluble due to the presence of up to four sulfonic acid groups. Acid dyes are applied on wool, silk and nylon when ionic bond is established between protonated amine group of fiber and acid group of dye. Throughout the range of acid dyes there is considerable variation in performance and methods of use. The dyer must be careful to ensure that the combination of dyes chosen is from the same group and has very similar properties.

Acid Dyes

As a professional supplier of high-efficiency dyes, Alfa Chemistry has the ability to provide customers with a comprehensive range of acid dyes.

Features of Acid Dyes

  1. Basically, acid dyes are soluble in water and are anionic in nature.
  2. Acid dyes usually used in combination with alkaline dyes.
  3. Acid dyes are suitable for wool, silk, polyamide and modified acrylics. While these dyes have no affinity for cotton cellulose and are therefore unsuitable for cellulose.
  4. Acid dyes are generally used in the presence of acids like sulphonic, acetic or formic acid to neutral pH bath.
  5. Acid dyes bind to fibers by hydrogen bonding, van der Waals forces, or ionic bonding.
  6. When acid dyes are treated with reducing agents, they are generally decolorized.
  7. Dyed acid colors have good light fastness and medium wash fastness.

Categories of Acid Dyes

The dyes are divided into three categories according to their levelling and fastness properties:

  • Levelling dyes

Levelling acid dyes have good leveling properties and can be used in baths containing sulfuric acid for leveling. Since the dye molecules migrate easily within and out of the fibers, levelling acid dyes have poor washing fastness and are usually used for light, bright shades where fastness is not of primary importance.

  • Milling dyes

Milling acid dyes are more substantial to fibers than leveling dyes and therefore have poorer leveling properties. These dyes have better color fastness than leveling acid dyes, especially under wet conditions.

  • Super-milling dyes

Super-milling acid or neutral dyeing dyestuffs are applied in a similar manner to milling acid dyestuffs, except that greater control is exercised over the rate of excellence of the dyestuffs. The fastness of super-milling dyes is very good, and with proper post-treatment they will meet the requirements of medium depth shades, especially where reasonable brightness is required.

Alfa Chemistry is committed to becoming a first-class, low-carbon, environmentally friendly dye supplier. Our mission is to provide customers with full specifications of high-quality dyes. We are also constantly expanding our product database to meet the wide range of customer needs. You are welcomed to contact us more acid dyes.

Reference

  1. P.R. Richards. Fabric Finishing, in Textiles and Fashion, 2015.

It is important to note that our products are for research use only and are not for clinical use.

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