PURPOSE: To obtain an iron oxide direct red pigment which maintains color purity by using a black magnetite seed suspension, an alkaline soln., iron (II) salt precipitate and oxygen-contg. gas and oxidizing the mixture until a required color tone is obtd.
CONSTITUTION: The black magnetic seed suspension having a specific surface area exceeding 60 m2/g and an average particle size below 0.05 μ is used as the seed suspension for synthesis of the pigment in the following manner, to obtain the desired pigment. Namely, the iron (II) salt soln. and metal or the iron (II) salt soln. and the alkaline soln. are added to the seed suspension and the suspension is oxidized by using the oxygen-contg. gas until the required color tone is obtd. The pure-colored iron oxide direct red pigment is obtd. by precipitation of the iron (II) salt using the alkaline soln. and the oxidation using the oxygen-contg. gas. The pigment is used in the form of a paste or slurry as a powder form pigment for coloring of lacquer, plastics, building materials and ceramics.
GUNTAA BUKUSUBAUMU
URURIKE PITSUTSUAA
