Patent ID: 8470912

Claim:
Method of producing a granulated colorant, which comprises a blending step for blending a powdery black oil-soluble nigrosine dye and water to form a blend, a granulation step for obtaining a cylindrical granulation colorant from the blend obtained in said blending step using an extrusion granulating machine, and a drying step for drying the cylindrical granulation colorant obtained in said granulation step, wherein said nigrosine dye is C.I. SOLVENT BLACK 5, C.I. SOLVENT BLACK 5:1, C.I. SLOVENT BLACK 5:2 or C.I. SLOVENT BLACK 7 and said cylindrical granulation colorant after drying by said drying step has a diameter of 2 to 4 mm, a length of 7 to 12 mm, bulk density of 0.4 to 0.7 g/ml and a hardness of 1 to 20 N.