To form a gradation pattern continuously changed in color phase by coating an object with two or more kinds of color powder coating materials with a specific wt. average particle size or less while changing the wt. ratio of the powder coating materials.
A resin and colorants, for example, a yellow colorant such as disazo yellow or an acetoacetate azoleamide type monoazo yellow pigment, a magenta colorant such as carmine 6B or pigment, red, a white colorant such as copper phthalocyanate or titanium oxide and a black colorant such as carbon black are kneaded in an extruder in a molten state and the resulting kneaded mixtures are cooled to be physically ground by a grinder such as a hammer mill, a jet impact mill, or the like, and subsequently classified by an air classifier to prepare two or mire kinds of color powder coating materials with a wt. average particle size of 20 μm or less and these coating materials are applied while the wt. ratios of them are changed. By this method, a gradation pattern changed in color phase continuously can be formed.
YOSHIMURA YOSHIO
SATO YUKIYA
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