| 摘要 |
PURPOSE: To obtain an org. - inorg. composite pigment having both a high chroma and a high hiding power by making Yellow No.4 aluminum lake uniformly and strongly adhere to the surface of a high-refractive-index inorg. white pigment to thereby composite the lake and the pigment. CONSTITUTION: This composite pigment is obtd. by coating an inorg. white pigment having a refractive index of 2 or higher and an average particle size of 0.01-60μm with Yellow No.4 aluminum lake. At least one white pigment selected from among zinc oxide, zirconium oxide, titanium oxide (anatase), and titanium oxide (rutile) is pref. used. This composite pigment is produced by a process comprising the step of dispersing the white pigment in an aluminum chloride soln. in pure water; the step of heating the dispersion, then adding a metallic aluminum powder to it, and continuing agitation under heating; the step of adding Yellow No.4 aluminum lake to the dispersion; and the step of adding a pH-adjusting agent (pref. an alkali metal carbonate) to the dispersion to adjust the pH to 5-2.
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