Prediction and influence of the mass proportion of trichromatic colourants and acrylic substrate on the optical and thermal performance of external wall coatings: An artificial neural network approach

Abstract

Colourants are the main components for the colour control of acrylic coatings for the external walls of buildings. Since the different mass proportions of cyan, magenta, and yellow colourants, the colour of the coating changes after mixing, which also affects the optical property and thermal performance of the coating. In this paper, an artificial neural network model is established, the BP algorithm is used for calculation, and the model is trained and verified by making and testing experimental samples to accurately predict the solar reflectivity by the mass proportions of trichromatic colourants and acrylic coating substrate. The mean square error is 0.0027. Meanwhile, the influence weights of the mass proportions of cyan, magenta, and yellow colourants and the acrylic coating substrate on the solar reflectivity are calculated by the model, which are 0.2863, 0.2209, and 0.4928, respectively. The increase in cyan colourant has a greater influence on the decrease in reflectivity of the blended coating. The outer surfaces of 11 samples were tested outdoors. Compared with the original solution of the acrylic coating, the maximum temperature difference of the mixed coating reached 16.03 °C. The highest temperature of the coating with the highest proportion of cyan colourant and the acrylic substrate is 10.61 °C higher than that of the coating with the lowest proportion. 1 There are only a few studies on the application of ANN in coating colour, and this is the first time that an artificial neural network model has been used to predict the coating reflectivity based on the mass proportion of trichromatic colourants to the acrylic substrate. 2 Based on the preparation and spectrum measurement of a large number of coating samples with different proportions of colourants and substrates, a cross-study of the material composition and optical properties has been carried out. 3 The influence of the different mass proportions of the trichromatic colourants to the substrate on the reflectivity of the coloured acrylic coating has been studied. The increase in the cyan colourant has the maximum impact on the decrease in reflectivity. The acrylic coating having the lowest proportion of the cyan colourant to the substrate shows a different temperature performance than that with highest proportion of the cyan colourant to the substrate.