펄 안료 함유 표면의 펄 느낌 정량화 연구

Abstract

Nowadays many effect pigments such as pearl or metallic flakes are commonly used in many commercial products such as electrical devices or car. To help the designer to choose the right color or for color management purposes, not only the color represented using hue, chroma and lightness but also the surface characteristics like gloss or pearliness needs to be quantified. In this study, the visually perceived pearliness is investigated to figure out whether an observer can perceive the pearliness as an intrinsic surface characteristics and whether the color measurement data using conventional color measurement devices could predict the visual pearliness or not. For the experiment, UV coated polycarbonate samples are prepared having three steps of pearl-pigment densities (2%, 5%, 8%) and average particle sizes (15 μm, 25 μm, 45 μm). Two types of base color are used, i.e. white and pink, and each sample is duplicated. Therefore in total 36 pearly samples are used in the experiment. Apart from the pearly samples, the three samples without pearl flakes are prepared having different gloss levels. All the samples are measured using glossmeter and spectrophotmeter with d/8 measurement geometry. Gloss measurement data shows that the gloss increases as the pearl flake densities and sizes are increased. CIELAB L* value decreases as the pearl flake's size increases while CIELAB C* value decreases as the pearl flake density increases when SCE mode data are used for calculation. It means that the pearl flake's size affects the specular reflection component mostly while the pearl flake's density affects the degree of scattering at the flake's surface. The psychophysical experimental data was conducted using the sample samples. Six observers participated and asked to quantify the degree of perceived pearliness of each sample. The result showed that perceived pearliness value is significantly increased as the pearl flake's size increases, which cannot be fully explained by the measurement data. Since this research demonstrated that current color measurement technique cannot explain the perceived pearliness, further research using various measurement devices needs to be conducted in the future.