Patent ID: 6241813
Filing Date: 2001-06-05
Classification: C09B

Abstract:
A process for preparing organic pigment granules with a particle size from 0.5 to 4 mm, which consist of at least 90% by weight of at least one organic pigment with a particle size from 0.01 to 10 .mu.m and from 0 to 10% by weight of a binder having from 2 to 7 mol of carboxyl groups per 1000 g and from 0 to 5% by weight of a neutral emulsifier which does not form ions and which dissolves to give a clear solution in water or a C.sub.1 -C.sub.4 alcohol at a concentration of at least 10 g/l 00 ml, the binder and the emulsifier together accounting for not more than 10% by weight and all percentages by weight being based on the overall amount of pigment granules, wherein[1] the pigment is mixed with 54-92% by weight of water, a C.sub.1 -C.sub.4 alcohol, a C.sub.3 -C.sub.8 ketone or a mixture thereof, based on the dry pigment, with the binder and 0.8-20 mol of ammonia or a C.sub.1 -C.sub.3 amine, per mole of carboxyl groups in the binder, and with the emulsifier;[2] this mixture is pressed in a continuously operating apparatus through one or more apertures each having a size of 0.2-5.0 mm.sup.2, the apparatus consisting of at least one conveying device and a shaping section comprising the apertures, and being constructed, and operated with a throughput, such that the pressure in its shaping section does not exceed 10 bar;[3] if desired, the cylindrical granules emerging from the dies are converted on a rotating device into ovoid or spherical granules, and[4] the granulated product is dried at a temperature of -50 to 200.degree. C. at atmospheric pressure or under reduced pressure.