| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for purifyingβ-quinophthalone to a high purity and a fluorescent magnetic powder containing the purifiedβ-quinophthalone and having a high fluorescent luminance and a high S/N ratio. SOLUTION: A method for purifyingβ-quinophthalone is provided which comprises the steps of: agitating crudeβ-quinophthalone crystals in an aqueous acid solution at a high speed to finely divide the crystals into colloidal particles having a mean particle diameter of 1μm or below and to thereby disperse the particles in the solution, dissolving a zinc compound contained in the crystals, removing the zinc compound by filtration and water washing after cooling, and drying the solid separated by filtration.
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