Visualization of the Paint Film Formation Process during Spray Coating

抄録

Volatile organic compounds (VOCs) released by paint are one cause of air pollution and human sickness. The spray coating method is often used when coating large areas such as vehicle bodywork and buildings. Although the relationship between spray characteristics and coated surface quality is clearly important, few investigations can be found in the literature. In this study, the droplet adhesion behavior when spray coating a wall surface was investigated experimentally. The characteristics of the paint film formed by the spray droplets were visualized, and the paint film thickness was measured using a fluorescence method to investigate the smoothing mechanism. Images of the coated surface recorded using a digital microscope were binarized to measure the ratio of coated area to uncoated area. At the start of the coating process, the ratio of coating area increased linearly with time and then the rate began to decrease. Coating was completed sooner when using a higher injection pressure. From the data of the coated area, the ratio of overlapping paint was also calculated, which can be used as an indication of excessive paint and became 350% at the maximum injection pressure used in this study.