The term “disperse dyes” have been applied to organic
coloring substances which are free from ionizing groups. They are of low water
solubility and are suitable for dyeing hydrophobic fibres. The dye has derived
its name for its insoluble acqueous properties and the need to apply it from an
acqueous dispersion. Of all the dyes they are of the smallest molecular size.
They have substantivity for one or more hydrophobic fibres
e.g. Cellulose acetate, nylon, polyester, acrylic and other synthetic fibres
The negative charge on the surface of hydrophobic fibres
like polyester can not be reduced by any names, so non-ionic dyes like disperse
dyes are used which are not influence by that surface charge.