The effects of TiO2 pigmented coatings characteristics on temperature and brightness of a coated black substrate

The high visible reflectivity of the cool coatings made by typical white pigment particles produces high glare, which is unpleasant to the human eye and possibly distorts the view of coated objects. A new approach to optimizing pigmented coatings considering both thermal and esthetic effects was proposed in previous works. For an accurate thermal analysis, a full spectral evaluation of radiative properties of pigmented coatings from UV to far IR wavelengths is required. We made a full spectral analysis of TiO2 pigment particles in polyethylene resin as the host medium in the wavelength range of 0.3-36 mu m. To find the spectral transmittance and reflectance of the pigmented layer, we conducted a radiation analysis using the radiation element method by ray emission model (REM2). The effects of characteristics of the coating layer, including size and volume concentration of pigment particles and coating thickness on esthetic and thermal behaviors were studied. The results show that by using the proposed optimum particle size, i.e., 0.8 mu m, it is possible to design a coating with reasonable temperature and moderate brightness. (C) 2011 Elsevier Ltd. All rights reserved.