Textile Dyes »
Dyes for Cellulose Fibers
» Azoic or Naphthol Dyes
| Dyes for Cellulose Fibers | Dyes for Protein Fibers | Dyes for Synthetic Fibers |
| Azoic or Naphthol Dyes | Bi Functional Dyes | Direct Dyes | Reactive Dyes | Sulphur Dyes | Vat Dyes | ||
| The name AZO has been derived from the word azote and it meant nitrogen in the ancient time in French. In Greek, a means not and zoe means to live. | ||
Azoic Dyes are also called as Azoic or Nepthol Dyes.
These AZO Dyes consist a group i.e. called AZO group having two nitrogen
atoms and this group (covalent bond) connects atomic ring compounds. The two
Nitrogen atoms are bonded with each other and form -N=N- as part of their
molecular structure. Azoic Dyes are found mainly in three colors and these
are red, brown and yellow. Aromatic amines are the chemicals from which
these dyes are manufactured.
Azoic Dyes are classified either according to the fibers
for which these can be used economically or the methods by which these dyes
are applied.
When these dyes are used upon the cellulose fabric then initially this fabric starts to suffer from poor rub fastness. This is due to the deposition of the free pigments on the surface of the fabric. This problem can be rectified by boiling the fabric in soap.
AZO Dyeing Process is such a process in which the
insoluble azoic dye is produced on the or within the fiber. By treating a
fiber with diazoic and coupling components, this process can be achieved.
After adjusting the dye bath conditions appropriately, the two above
mentioned components react. From this reaction the required insoluble AZO
dye is produced. This is a unique technique. The required color can be
changed by altering of the diazoic and coupling components.
