ABSTRACT
The effect of particle size on the coloring properties of aluminum dye lakes was studied. Lakes impart color by dispersion in the medium to be colored. Dispersion techniques were developed, using scanning electron micrographs for particle sizing. The color strength and the trichromatic colorimetric properties were calculated from reflectance values measured from "drawdown" films. The results clearly show that the coloring properties of lakes are related to the surface of lake that is wetted by the medium, and resemble results obtained in paint systems. The submicron particles are especially important, contributing greatly to the color strength. The results also agree with theoretical predictions based on certain assumptions for the refractive index of the lakes. The utility of the CIE 1976 L*a*b* color space is demonstrated by quantifying changes in hue, chroma, lightness, and total color difference with different dispersion levels.
Subject(s)
Aluminum/analysis , Coloring Agents/analysis , Chemical Phenomena , Chemistry, Physical , Chromatography, Ion Exchange , Color , Colorimetry , Particle SizeABSTRACT
The effect of processing variables on the type of aluminum hydroxide and the dye content of the resultant lakes were investigated. The solid-state structure of aluminum lakes in conjunction with the associated aluminum hydroxide was studied by electron microscopy, X-ray diffraction, and IR spectroscopy. The conditions under which the aluminum hydroxide was prepared were shown to govern the amorphous/crystalline character of the product, which was reflected in changes in particle size and surface area. A hypothesis for the interaction of the dye and aluminum hydroxide is formulated in which the amount of dye adsorbed on the aluminum hydroxide is dependent on the surface area of the microstructures present.
