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Analysis Of Acid Dyes
Apr 24, 2018

Acid direct dyes must have significant dyeing effect after adding alum and other cationic mordant. The addition of urea formaldehyde resin or cationic PEI, as a mordant, rejects the direct dyes containing the cationic dyes, making the paper with direct dyes such as alum hard to retain its special strength, permeability and softness, and the tone of the color is due to the increase of PEL and other dark quantities. Acid direct dyes are water-soluble dyes with structural acidic groups and are dyed in acid medium. Most of the acid direct dyes contain sodium sulfonate, soluble in water, completely chromatograph and bright in color. It is mainly used for dyeing nylon, wool and silk, and also for ink, paper, leather and so on. Cellulose fibers are usually colored.

Acid direct dyes are divided into weak acid, acid complex dyes and strong acid acidic medium according to their chemical structure and dyeing conditions.


Direct dyes of weak acid can be produced by increasing molecular weight, introducing aryl sulfone group or introducing long carbon chain in strong acid direct dyes. The molecular structure of wool affinity is complex, and it can weaken the medium in wool dyeing. There is no damage to wool, dark color, and the fastness of wool, but the dyeing is not uniform. Such as weak acid and brilliant blue RAW.

2. folded strong acid direct dyes

The first developed acid direct dyestuff, which requires strong dyeing in the acid bath, is simple in molecular structure, low in molecular weight, contains sulfonyl or carboxyl groups. The affinity for wool is small, the wool is uniform, and the dyeing is uniform. It is also called the acid dye leveling, but the shadow is not deep, the washing fastness is poor and the wool is dyed when dyed. The wool feels bad after dyed.

The above is the content of acid direct dyes. It is better to know the acid direct dyes.