PROBLEM TO BE SOLVED: To provide a pigment powder surface treatment method that allows an increased amount of poorly soluble organic acid compounds to be uniformly attached to the surface of a pigment than in the conventional method.SOLUTION: In an aqueous solution, in which a poorly water-soluble organic acid compound having a carboxy group in the molecular structure is dissolved in water as a salt under basic conditions, a pigment powder is mixed and dispersed, and the aqueous solution is made acidic, so that the poorly water-soluble organic acid compound is precipitated on the surface of the pigment powder for surface treating. Embodiments 1,2, surface-treated by the surface treatment method, have a better UV adsorption ability than those of Comparative examples 1,2, surface-treated by mechanochemical surface treatment methods.SELECTED DRAWING: Figure 1COPYRIGHT: (C)2019,JPO&INPIT【課題】従来方法よりも、多くの難溶性有機酸化合物を均一に顔料表面に付着させることのできる顔料粉体の表面処理方法を提供する。【解決手段】分子構造中にカルボキシ基を有する水難溶性有機酸化合物を塩基性条件下で塩として水に溶解させた水溶液中に顔料粉体を混合分散し、該水溶液を酸性にすることにより、水難溶性有機酸化合物を顔料粉体の表面に析出させて表面処理する。この表面処理方法によって表面処理した実施例1,2は、メカノケミカル的な表面処理方法によって表面処理した比較例1,2よりもUV吸収能が優れるものとなる。【選択図】図1
