**Dispersing agent**

Disperse dyes are sparingly soluble in water and often crystalline with varying particle size. These characteristics are inadequate for dispersing the dyes in water and cause unlevel dyeing. In order to achieve the required particle size and distribution (Heimanns, 1981), the disperse dye is milled, usually in the presence of a dispersing agent (Derbyshire et al, 1972). Generally, the dispersing agents are anionic, ligninsulphonates or polycondensates of arylsulphonic acids with formaldehyde which facilitate milling by preventing agglomeration of the dye particles.
