Patent ID: 6890380

Claim:
A method for the preparation of a conditioned organic pigment, comprising the steps wherein (1) a pigment suspension is formed through synthesis of an organic pigment in a liquid reaction medium and precipitation of the thus synthesized pigment from said liquid reaction medium; (2) the pigment suspension from step (1) is transferred into a storage vessel, keeping the pigment surface substantially wetted throughout the transfer with said liquid reaction medium, a washing agent, a polar liquid or water; (3) if the liquid medium of the pigment suspension in the storage vessel does not already consist of water and from 1 to 30% by weight of a neutral, polar liquid, based on the total amount of liquid and water, the composition of the pigment suspension is so modified by means of the addition of water and/or neutral, polar liquid having a dipole moment μ of 2.8-6.0·10 −18 esu so that the amount of neutral, polar liquid is from 1 to 30% by weight, based on the total amount of liquid and water; (4) the pigment suspension from the storage vessel is passed a number of times through an agitated media pearl mill having a radial speed in a circulating or shuttle mode of operation, the agitated media pearl mill having a smaller chamber volume than the volume of the pigment suspension and being operated at a specific power density of at most 2.0 kJ·s −1 per liter of grinding space; (5) the pigment is isolated by removing the liquid surrounding it.