Disperse dyes are insoluble in
water and form an aqueous dispersion in water. At first these dye molecules are
formed as large particles and they are made smaller particles by grinding. But as
they are water insoluble, they will give uneven dyeing if they are directly
used in dye bath. So to ensure uniform and trouble- free dyeing the dye should
be present in dye bath in an uniform very fine form and should give an stable
dispersion. This is the reason for which a special chemical is used in dye
bath, named dispersing agent. They should be effective under dyeing conditions.
Stable to hard water, high temperature abd other dyeing assistants.
For example, soa powder, Turky red oil, alkali
sulphates, alkyle arylphonates etc are same surface active agent which are
recommended as dispersing agents in disperse dyeing.