Classes of acid dyes
Acidic dyes can be classified according to their dyeing behavior. This includes their wet fastness, migration ability, and dyeing pH:[1]
- Leveling acid dyes: These dyes have relatively low molecular weights. Consequently, they migrate more readily before fixation and they exhibit low wet fastness. They are not normally suited for use as apparel fabric. They require an acidic dye bath, often using sulfuric acid and sodium sulfate mixtures (pH2-4),[7] together with leveling agents such as ethoxylated fatty amines.
- Milling dyes: These dyes are high molecule weight, with the result that migrates slowly. Consequently, they exhibit wet fastness, which is useful for dyeing wool materials. Milling acid dyes are sometimes called 'Neutral acid dyes' as they do not require an acidic dye bath. They are commonly applied using Acetic acid (pH4-7).[7]
- Metal complex acid dyes: These dyes are composed of acid dye molecules complexed with a metal ion, which will usually be chromium or cobalt. Metal complex acid dyes have high molecular weights, giving them low mobility and high wet fastness. Due to this, they are commonly used on nylon and synthetic polyamide fibers. Metal complex acid dyes are economical. However, they produce relatively dull shades. Metal complex acid dyes take a larger range of pH in the dyebath (pH2-7).[7]
https://en.wikipedia.org/wiki/Acid_dye
No comments:
Post a Comment