Process for fine division of organic pigments by precipitation

摘要

The invention provides a process for the fine division of pigments which 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 being passed into the reactor chamber through an opening in the housing for the purpose of maintaining a gas atmosphere in the reactor chamber, and the resulting pigment suspension and the gas or the evaporated liquid being 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.