Crystalline nickel chelate of 1-nitroso-2-naphthol and process for producing same

Claim 1

In a process for producing a pigmentary composition comprising a crystalline, light-stable nickel chelate of 1-nitroso-2-naphthol characterized by having an X-ray diffraction pattern which exhibits strongest d-spacings at about 11.6, 9.6, 6.0, 4.9, 4.5 and 3.6 Angstroms by treating particles of a hydrated nickel chelate of 1-nitroso-2-naphthol in aqueous medium with from about 0.10 to about 1.0 mole per mole of chelate of an inert, water-immiscible, poly(vinyl chloride) ester plasticizer which is a non-solvent for the nickel chelate and has a boiling point above about 200° C. until the particles are wetted, isolating the wetted product from the aqueous medium, and then heating the isolated product at a temperature ranging from about 65° C. to about 105° C. until the product is dehydrated and converted to the anhydrous, crystalline, light-stable form, the improvement which comprises carrying out the treatment step in aqueous medium which additionally contains from about 0.05 to about 1 part per part of anhydrous nickel chelate of at least one fatty acid containing at least 12 carbon atoms or a water-insoluble, normally solid salt thereof at a pH between about 3.5 and 5.0 and at a temperature at which the fatty acid and/or its salt and the plasticizer are liquid.