PROCESS FOR FINE DIVISION OF ORGANIC PIGMENTS BY PRECIPITATION

摘要

PURPOSE: Provided is a universally applicable and industrially reliable process for the fine division of organic pigments by precipitation, which prevents the possibility of contamination by foreign substances and produces especially fine particles with a particularly narrow size distribution. CONSTITUTION: The process for the fine division of pigments comprises dissolving coarsely crystalline crude pigments in a solvent and precipitating them with a liquid precipitation medium by spraying the pigment solution and the precipitation medium through nozzles to a point of conjoint collision in a reactor chamber enclosed by a housing in a microjet reactor. A gas or an evaporating liquid is passed into the reactor chamber through an opening in the housing for the purpose of maintaining a gas atmosphere in the reactor chamber. The resulting pigment suspension and the gas or the evaporated liquid are removed from the reactor through a further opening in the housing by means of overpressure on the gas entry side or underpressure on the product and gas exit side.