Process for the continuous production of dispersions

Dispersions having a finely divided state are produced by suspending and subdividing a solid in a liquid medium, in a mill of the agitator type (see Division B1). Among examples of dispersions quoted are: (a) 40 kg. of dyestuff C.1 Pigment Red 112 and 60 kg. of an aqueous solution containing 20% by weight of the reaction product of 1 mole of hydroxydiphenyl and 1 mole of benzyl chloride to which 12-14 moles of ethylene oxide has been added per mole. The pigment dispersion contains 40% by weight in a state of subdivision less than 15 m . The above reaction product may be replaced by equivalent amounts of other tensides. (b) A dispersion of a -modification copper phthalocyanine and the sodium salt of lignin-sulphonic acid is produced having 26.5% by weight of the pigment having a particle size of less than 5 m .ALSO:A process for preparing a dispersion having a finely divided state by suspending and subdividing a solid in a liquid medium comprises passing continuously, under pressure, a solid in a non-pumpable state and simultaneously a liquid medium into an agitated layer of spherical grinding elements of 0.3 to 10 mm. diameter, passing the solid together with the liquid medium through the agitated layer and separating continuously the dispersion formed from the grinding elements of the agitated layer. The solid may be dry or combined with the liquid medium, in the form of a press cake. The grinding elements may be agitated by rotation at circumferential speeds from 4-20 m/sec. or vibration using crossed blades, stirring rods of streamline cross-section, screws, and flat or conical compact or perforated discs or rings connected to a shaft by spokes.