体質顔料との複合化による有機顔料の高彩度化とその性質

抄録

A color locus of a certain color pigment mixture is generally known draw a specific loop on a chromaticity diagram. It was found that an increase in chroma without any change of hue and value was observed by the addition of BaSO₄, an extender pigment, to a dispersion of Lithol rubine B (R-201) in caster oil. In addition, the chroma of the dispersion increased as the difference of the refractive indexes between the added extender pigment and caster oil decresed. The mechanism of the enhancement in the chroma was considered to be due to a “spacer effect”. It increases an optical dispersing ability of color pigments by means of the extender pigments, which are inserted among the particles of Lithol rubine B. The same phenomenon was also observed when Lithol rubine BCA (R-202) was used.
In order to advance the spacer effect and to stabilize it, the color pigments and the extender pigments were hybridized using a ball mill. The chroma of this hybridized pigment was greater than that of simply mixed pigments, and the hybridized one also had an excellent dispersing ability. The structural analysis of the hybridized pigments by means of the cross-sectional observation using scanning electron microscopy (SEM) demonstrated that the surface of extender pigment was covered with color pigment particles uniformly. The thickness of the color pigments layer could be controlled by the ratio of hybridization. Furthermore, the hybridized pigment was found to yield almost same effects as the color pigments of smaller particle size which were well dispersed. This result is explained by an increase in absorption and a changes in scattering due to decreased color pigment thickness of hybridized pigments.