| abstract |
The present invention relates to a process for the preparation of a yellow pigment based on a complex of nickel cation, melamine and azobarbituric acid of the formula [NiLM.sub.mn] .sub.nn, where L is the anion of azobarbituric acid C.sub.8.nHsub.4.nNsub .6.nOne.6, M Marked Melamine C.Sub.3.nHsub.6.nNubs.6., M = 0.1 to 2, n.> =. 2 in which a nickel (II) chloride / melamine complex is prepared in the first step and the complex is reacted with the azobarbituric acid or its salt in the second reaction step. Further, the present invention describes novel crystal modifications of this pigment obtainable by this method. |